Patent Publication Number: US-2021167487-A1

Title: Handheld electronic device

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
     This application is a nonprovisional patent application of and claims the benefit of U.S. Provisional Patent Application No. 62/943,199, filed Dec. 3, 2019 and titled “Handheld Electronic Device,” and U.S. Provisional Patent Application No. 62/946,920, filed Dec. 11, 2019 and titled “Handheld Electronic Device,” and U.S. Provisional Patent Application No. 63/047,760, filed Jul. 2, 2020 and titled “Handheld Electronic Device,” the disclosures of which are hereby incorporated herein by reference in their entireties. 
    
    
     FIELD 
     The subject matter of this disclosure relates generally to handheld electronic devices, and more particularly, to mobile phones. 
     BACKGROUND 
     Modern consumer electronic devices take many shapes and forms, and have numerous uses and functions. Smartphones, for example, provide various ways for users to interact with other people that extend beyond telephone communications. Such devices may include numerous systems to facilitate such interactions. For example, a smartphone may include a touch-sensitive display for providing graphical outputs and for accepting touch inputs, wireless communications systems for connecting with other devices to send and receive voice and data content, cameras for capturing photographs and videos, and so forth. However, integrating these subsystems into a compact and reliable product that is able to withstand daily use presents a variety of technical challenges. The systems and techniques described herein may address many of these challenges while providing a device that offers a wide range of functionality. 
     SUMMARY 
     Some example embodiments are directed to a mobile phone including a housing structure that defines a side surface of the mobile phone. The mobile phone may also include a front cover coupled to the housing structure and defining a front surface of the mobile phone, and a rear cover coupled to the housing structure and defining a rear surface of the mobile phone. The mobile phone may also include a display positioned below the front cover. The mobile phone may also include first directional antenna defining a first radiation pattern extending through the front surface of the mobile phone, a second directional antenna defining a second radiation pattern extending through the rear surface of the mobile phone, and a third directional antenna defining a third radiation pattern extending through the side surface of the mobile phone. The first directional antenna, the second directional antenna, and the third directional antenna may be configured to operate at a frequency band between about 25 GHz and about 39 GHz. 
     In some cases, the frequency band is a first frequency band, the first directional antenna, the second directional antenna, and the third directional antenna define a first antenna group. The mobile phone may also include a second antenna group configured to operate at a second frequency band different than the first frequency band, and a third antenna group configured to operate at a third frequency band different than the first frequency band and the second frequency band. In some implementations, the housing structure includes: a first conductive component defining a first portion of the side surface of the mobile phone; a second conductive component defining a second portion of the side surface of the mobile phone; and a nonconductive joining element retaining the first conductive component and the second conductive component and defining a third portion of the side surface of the mobile phone. The first conductive component defines a first antenna of the second antenna group, and a first antenna of the third antenna group. The second antenna group may define a first multiple-in multiple-out antenna array. The third antenna group may define a second multiple-in multiple-out antenna array. 
     In some cases, the first radiation pattern extends along a first primary transmission direction. The second radiation pattern may extend along a second primary transmission direction that is different from the first primary transmission direction. The third radiation pattern may extend along a third primary transmission direction that is different from the first primary transmission direction and different from the second primary transmission direction. In some cases, a first antenna gain of the first directional antenna is highest along the first primary transmission direction, a second antenna gain of the second directional antenna is highest along the second primary transmission direction, and a third antenna gain of the third directional antenna is highest along the third primary transmission direction. The second primary transmission direction may be orthogonal to the first primary transmission direction and to the third primary transmission direction. 
     In some embodiments, the first directional antenna comprises: a first directional antenna element configured to operate at a first frequency; and a second directional antenna element configured to operate at a second frequency different from the first frequency. In some cases, the second directional antenna comprises: a third directional antenna element configured to operate at the first frequency; and a fourth directional antenna element configured to operate at the second frequency. 
     Some example embodiments are directed to a portable electronic device including a housing structure, a display, a front cover, a rear cover, and an antenna array. The housing structure may define a side wall defining at least a portion of a side surface of the portable electronic device and an antenna window formed in the side wall, The antenna window may define a first hole extending through the side wall and a second hole extending through the side wall. The display may be at least partially within the housing structure. The front cover may be coupled to the housing structure and define a front surface of the portable electronic device. The rear cover may be coupled to the housing structure and define a rear surface of the portable electronic device. The antenna array may include: a first directional antenna element configured to operate at a first frequency and defining a first radiation pattern extending through the first hole; and a second directional antenna element configured to operate at a second frequency, different from the first frequency, and defining a second radiation pattern extending through the second hole. 
     In some cases, the antenna window further defines a third hole extending through the side wall, and a fourth hole extending through the side wall. The antenna array may further comprise: a third directional antenna element configured to operate at the first frequency and defining a third radiation pattern extending through the third hole; and a fourth directional antenna element configured to operate at the second frequency and defining a fourth radiation pattern extending through the fourth hole. The first hole may define a first waveguide, and the second hole may define a second waveguide. A first nonconductive cover element may be positioned in the first hole, and a second nonconductive cover element may be positioned in the second hole. 
     In some cases, the portion of the side surface of the portable electronic device is a first portion of the side surface of the portable electronic device, the side wall defines a recessed region having a bottom surface, and the first hole and the second hole are formed along the bottom surface of the recessed region. In some cases, the portable electronic device further comprises a third nonconductive cover element in the recessed region and defining a second portion of the side surface of the portable electronic device. 
     The first nonconductive cover element and the second nonconductive cover element may be adhered to the third nonconductive cover element. The side wall may be formed from a conductive material and is a radiating member of an antenna system. 
     Some example embodiments are directed to portable electronic device comprising: a housing member defining a side surface of the portable electronic device; a front cover coupled to the housing member and defining a front surface of the portable electronic device; a rear cover coupled to the housing member and defining a rear surface of the portable electronic device; a display positioned below the front cover; and an antenna array. The antenna array may include a first directional antenna element configured to operate at a first frequency and defining a first radiation pattern extending through the front cover along a first direction perpendicular to the front surface of the portable electronic device. The antenna array may also include a second directional antenna element configured to operate at a second frequency different from the first frequency and defining a second radiation pattern extending through the front cover along a second direction perpendicular to the front surface of the portable electronic device. 
     In some cases, the antenna array further comprises: a third directional antenna element configured to operate at the first frequency and defining a third radiation pattern extending through the front cover along a third direction; and a fourth directional antenna element configured to operate at the second frequency and defining a fourth radiation pattern extending through the front cover along a fourth direction. The first direction, the second direction, the third direction, and the fourth direction may be parallel to one another. 
     In some cases, the antenna array comprises a circuit substrate, the first directional antenna element is a first ceramic post conductively coupled to the circuit substrate, and the second directional antenna element is a second ceramic post conductively coupled to the circuit substrate. The antenna array may further comprise a polymer cover structure at least partially encapsulating the first ceramic post and the second ceramic post. The polymer cover structure may define an air gap between the first ceramic post and the second ceramic post. 
     In some implementations, the antenna array further comprises: a first set of conductive contacts in contact with the first ceramic post and soldered to the circuit substrate; a first polymer retention structure securing the first set of conductive contacts to the first ceramic post; a second set of conductive contacts in contact with the second ceramic post and soldered to the circuit substrate; and a second polymer retention structure securing the second set of conductive contacts to the second ceramic post. The polymer cover structure may at least partially encapsulate the first polymer retention structure and the second polymer retention structure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The disclosure will be readily understood by the following detailed description in conjunction with the accompanying drawings, wherein like reference numerals designate like structural elements, and in which: 
         FIGS. 1A-1B  depict an example electronic device; 
         FIGS. 1C-1D  depict another example electronic device; 
         FIG. 2  depicts an exploded view of an example electronic device; 
         FIG. 3  depicts an exploded view of an example electronic device; 
         FIG. 4  depicts an exploded view of an example electronic device; 
         FIG. 5  depicts an exploded view of an example electronic device; 
         FIG. 6A  depicts a cross-sectional view of a portion of an example electronic device; 
         FIGS. 6B-6D  depict a cross-sectional view of a portion of an example electronic device; 
         FIG. 6E  depicts a cross-sectional view of a portion of an example electronic device; 
         FIGS. 6F-6I  depict cross-sectional views of example front covers for an electronic device; 
         FIG. 7  depicts a partial view of an example electronic device; 
         FIG. 8A  depicts an example antenna arrangement for an example electronic device; 
         FIGS. 8B-8D  depict example antenna use cases for an example electronic device; 
         FIGS. 9A-9B  depict an example side-fired antenna window for an electronic device; 
         FIG. 10A  depicts an example front-fired antenna for an electronic device; 
         FIG. 10B  depicts another example front-fired antenna for an electronic device; 
         FIG. 10C  depicts another example front-fired antenna for an electronic device; 
         FIG. 10D  depicts a side view of the front-fired antenna of  FIG. 10C ; 
         FIG. 10E  depicts a perspective view of the front-fired antenna of  FIG. 10C ; 
         FIG. 11  depicts example antenna feed and ground points for an electronic device; 
         FIG. 12A  depicts a partial view of a housing member for an electronic device; 
         FIG. 12B  depicts a partial cross-sectional view of a housing of an electronic device including the housing member of  FIG. 12A ; 
         FIG. 12C  depicts a partial view of a housing member for an electronic device; 
         FIG. 12D  depicts a partial cross-sectional view of a housing of an electronic device including the housing member of  FIG. 12C ; 
         FIG. 12E  depicts a partial cross-sectional view of a housing of an electronic device including the housing members of  FIG. 12A  and  FIG. 12C ; 
         FIG. 12F  depicts a partial view of an electronic device showing a coupling structure for housing members; 
         FIG. 12G  depicts a partial view of an electronic device showing another coupling structure for housing members; 
         FIG. 12H  depicts a partial view of an electronic device showing another coupling structure for housing members; 
         FIG. 13A  depicts an exploded view of an example cover and display stack of an electronic device; 
         FIG. 13B  depicts an exploded view of another example cover and display stack of an electronic device; 
         FIG. 13C  depicts a partial cross-sectional view of an electronic device; 
         FIG. 13D  depicts a partial cross-sectional view of a portion of the electronic device of  FIG. 13C ; 
         FIG. 14A  depicts a portion of an electronic device illustrating an example sensor array; 
         FIG. 14B  depicts an exploded view of a camera portion of an example electronic device; 
         FIGS. 14C-14D  depict partial cross-sectional views of depth sensor modules of an example electronic device; 
         FIG. 14E  depicts a bracket member for camera modules of an electronic device; 
         FIG. 14F  depicts a partial cross-sectional view of an example electronic device, illustrating aspects of a camera trim structure; 
         FIG. 14G  depicts a portion of an electronic device with a frame member attached to a housing; 
         FIG. 14H  depicts a partial cross-sectional view of camera modules of an example electronic device; 
         FIG. 14I  depicts an exploded view of camera components of an example electronic device; 
         FIG. 14J  depicts flexible circuit elements for conductively coupling components of an example electronic device; 
         FIG. 15A  depicts an exploded view of an example camera of an electronic device; 
         FIG. 15B  depicts a cross-sectional view of a component of the camera of  FIG. 15A ; 
         FIG. 16A  depicts a flash module of an example electronic device; 
         FIG. 16B  depicts a partial cross-sectional view of the flash module of  FIG. 16A ; 
         FIG. 16C  depicts a partial cross-sectional view of another example flash module; 
         FIG. 16D  depicts a process of assembling flash modules; 
         FIG. 17A  depicts a partial cross-sectional view of an example electronic device; 
         FIGS. 17B-17G  depict partial cross-sectional views of housing members and cover configurations for electronic devices; 
         FIGS. 17H-17I  depict partial cross-sectional views of covers for electronic devices; 
         FIG. 18  depicts a partial view of an interior of an example electronic device; 
         FIG. 19A  depicts an example haptic actuator for an example electronic device; 
         FIG. 19B  depicts another example haptic actuator for an example electronic device; 
         FIG. 20A  depicts a partial cross-sectional view of a speaker portion of an example electronic device; 
         FIG. 20B  depicts an exploded view of the electronic device of  FIG. 20A ; 
         FIG. 20C  depicts a partial cross-sectional view of a speaker portion of an example electronic device; 
         FIG. 20D  depicts an example sealing assembly for a speaker of an example electronic device; 
         FIG. 21A  depicts an example component assembly positioned along an upper region of a display; 
         FIG. 21B  depicts a partial exploded view of the component assembly of  FIG. 21A ; 
         FIG. 21C  depicts a partial cross-sectional view of a flood illuminator; 
         FIG. 21D  depicts another partial cross-sectional view of the flood illuminator; 
         FIG. 21E  depicts an example light transmissive component for a flood illuminator; 
         FIG. 21F  depicts another example light transmissive component for a flood illuminator; 
         FIG. 21G  depicts an ambient light sensor; 
         FIG. 21H  depicts an exploded view of the ambient light sensor of  FIG. 21G ; 
         FIG. 21I  depicts another example ambient light sensor; 
         FIGS. 22A-22C  depict an example battery for an electronic device; 
         FIGS. 22D-22E  depict partial cross-sectional views of example batteries; 
         FIG. 23A  depicts an example logic board for an electronic device; 
         FIG. 23B  depicts an exploded view of the logic board of  FIG. 23A ; 
         FIG. 23C  depicts a back view of the logic board of  FIG. 23A ; 
         FIG. 23D  depicts a partial cross-sectional view of a portion of the logic board of FIG. 
         23 A; 
         FIG. 23E  depicts a partial cross-sectional view of another portion of the logic board of  FIG. 23A ; 
         FIG. 23F  depicts a partial cross-sectional view of another portion of the logic board of  FIG. 23A ; 
         FIGS. 24A-24C  depict exploded views of example multi-layer configurations for electronic components of an electronic device; and 
         FIG. 25  depicts a schematic diagram of an example electronic device. 
     
    
    
     DETAILED DESCRIPTION 
     Reference will now be made in detail to representative embodiments illustrated in the accompanying drawings. It should be understood that the following descriptions are not intended to limit the embodiments to one preferred embodiment. To the contrary, it is intended to cover alternatives, modifications, and equivalents as can be included within the spirit and scope of the described embodiments as defined by the appended claims. 
     Mobile phones as described herein may include complex, sophisticated components and systems that facilitate a multitude of functions. For example, mobile phones according to the instant disclosure may include touch- and/or force-sensitive displays, numerous cameras (including both front- and rear-facing cameras), GPS systems, haptic actuators, wireless charging systems, and all requisite computing components and software to operate these (and other) systems and otherwise provide the functionality of the mobile phones. 
       FIG. 1A  shows an example electronic device  100  embodied as a mobile phone. While the device  100  is a mobile phone, the concepts presented herein may apply to any appropriate electronic devices, including portable electronic devices, wearable devices (e.g., watches), laptop computers, handheld gaming devices, tablet computers, computing peripherals (e.g., mice, touchpads, keyboards), or any other device. Accordingly, any reference to an “electronic device” encompasses any and all of the foregoing. 
     The electronic device  100  includes a cover  102  (e.g., a front cover), such as a glass, glass-ceramic, ceramic, plastic, sapphire, or other substantially transparent material, component, or assembly, attached to a housing  104  (which may include a housing structure defined by one or more housing members). The cover  102  may be positioned over a display  103 . The cover  102  may be formed from glass (e.g., a chemically strengthened glass), sapphire, ceramic, glass-ceramic, plastic, or another suitable material. The cover  102  may be formed as a monolithic or unitary sheet. The cover  102  may also be formed as a composite of multiple layers of different materials, coatings, and other elements. 
     The display  103  may be at least partially positioned within the interior volume of the housing  104 . The display  103  may be coupled to the cover  102 , such as via an adhesive or other coupling scheme. The display  103  may include a liquid-crystal display (LCD), a light-emitting diode, an organic light-emitting diode (OLED) display, an active layer organic light emitting diode (AMOLED) display, an organic electroluminescent (EL) display, an electrophoretic ink display, or the like. The display  103  may be configured to display graphical outputs, such as graphical user interfaces, that the user may view and interact with. The device  100  may also include an ambient light sensor that can determine properties of the ambient light conditions surrounding the device  100 . The device  100  may use information from the ambient light sensor to change, modify, adjust, or otherwise control the display  103  (e.g., by changing a hue, brightness, saturation, or other optical aspect of the display based on information from the ambient light sensor). 
     The display  103  may include or be associated with one or more touch- and/or force-sensing systems. In some cases, components of the touch- and/or force-sensing systems are integrated with the display stack. For example, electrode layers of a touch and/or force sensor may be provided in a stack that includes display components (and is optionally attached to or at least viewable through the cover  102 ). The touch- and/or force-sensing systems may use any suitable type of sensing technology, including capacitive sensors, resistive sensors, surface acoustic wave sensors, piezoelectric sensors, strain gauges, or the like. The outer or exterior surface of the cover  102  may define an input surface (e.g., a touch- and/or force-sensitive input surface) of the device. While both touch- and force-sensing systems may be included, in some cases the device  100  includes a touch-sensing system and does not include a force-sensing system. 
     The device  100  may also include a front-facing camera  106 . The front-facing camera  106  may be positioned below or otherwise covered and/or protected by the cover  102 . The front-facing camera  106  may have any suitable operational parameters. For example, the front-facing camera  106  may include a 12 megapixel sensor (with 1 micron pixel size), and an 80-90° field of view. The front-facing camera  106  may have fixed focus optical elements with an aperture number of f/2.2. Other types of cameras may also be used for the front-facing camera  106 . 
     The device  100  may also include one or more buttons (e.g., buttons  116 ,  120 ), switches (e.g., switch  118 ), and/or other physical input systems. Such input systems may be used to control power states (e.g., the button  120 ), change speaker volume (e.g., the buttons  116 ), switch between “ring” and “silent” modes, and the like (e.g., the switch  118 ). 
     The device  100  may also include a speaker port  110  to provide audio output to a user, such as to a user&#39;s ear during voice calls. The speaker port  110  may also be referred to as an earpiece in the context of a mobile phone. The device  100  may also include a charging port  112  (e.g., for receiving a power cable for providing power to the device  100  and charging the battery of the device  100 ). The device  100  may also include audio openings  114 . The audio openings  114  may allow sound output from an internal speaker system (e.g., the speaker system  224 ,  FIG. 2 ) to exit the housing  104 . The device  100  may also include one or more microphones. In some cases, a microphone within the housing  104  may be acoustically coupled to the surrounding environment through an audio opening  114 . 
     The housing  104  may be a multi-piece housing. For example, the housing  104  may be formed from multiple housing members  124 ,  125 ,  126 ,  127 ,  128 , and  130 , which are structurally coupled together via one or more joint structures  122  (e.g.,  122 - 1 - 122 - 6 ). Together, the housing members  124 ,  125 ,  126 ,  127 ,  128 , and  130  and the joint structures  122  may define a band-like housing structure that defines four side walls (and thus four exterior side surfaces) of the device  100 . Thus, both the housing members and the joint structures define portions of the exterior side surfaces of the device  100 . 
     The housing members  124 ,  125 ,  126 ,  127 ,  128 , and  130  may be formed of a conductive material (e.g., a metal such as aluminum, stainless steel, or the like), and the joint structures  122  may be formed of one or more polymer materials (e.g., glass-reinforced polymer). The joint structures  122  may include two or more molded elements, which may be formed of different materials. For example, an inner molded element may be formed of a first material (e.g., a polymer material), and an outer molded element may be formed of a second material that is different from the first (e.g., a different polymer material). The materials may have different properties, which may be selected based on the different functions of the inner and outer molded elements. For example, the inner molded element may be configured to make the main structural connection between housing members, and may have a higher mechanical strength and/or toughness than the outer molded element. On the other hand, the outer molded element may be configured to have a particular appearance, surface finish, chemical resistance, water-sealing function, or the like, and its composition may be selected to prioritize those functions over mechanical strength. 
     In some cases, one or more of the housing members  124 ,  125 ,  126 ,  127 ,  128 , and  130  (or portions thereof) are configured to operate as antennas (e.g., members that are configured to transmit and/or receive electromagnetic waves to facilitate wireless communications with other computers and/or devices). To facilitate the use of the housing members as antennas, feed and ground lines may be conductively coupled to the housing members to couple the housing members to other antennas and/or communication circuitry.  FIG. 11 , described in more detail below, depicts example antenna feed and ground lines for an example device. Further, the joint structures  122  may be substantially non-conductive to provide suitable separation and/or electrical isolation between the housing members (which may be used to tune the radiating portions, reduce capacitive coupling between radiating portions and other structures, and the like). In addition to the housing members  124 ,  125 ,  126 ,  127 ,  128 , and  130 , the device  100  may also include various internal antenna elements that are configured to transmit and receive wireless communication signals through various regions of the housing  104 . As shown in  FIG. 1A , the device  100  may include an antenna window  129  that allows for the passage of radio-frequency communication signals through a corresponding region of the housing  104 . 
     The joint structures  122  may be mechanically interlocked with the housing members to structurally couple the housing members and form a structural housing assembly. Further details about the joint structures  122  and their mechanical integration with the housing members are provided herein. 
     The exterior surfaces of the housing members  124 ,  125 ,  126 ,  127 ,  128 , and  130  may have substantially a same color, surface texture, and overall appearance as the exterior surfaces of the joint structures  122 . In some cases, the exterior surfaces of the housing members  124 ,  125 ,  126 ,  127 ,  128 , and  130  and the exterior surfaces of the joint structures  122  are subjected to at least one common finishing procedure, such as abrasive-blasting, machining, polishing, grinding, or the like. Accordingly, the exterior surfaces of the housing members and the joint structures may have a same or similar surface finish (e.g., surface texture, roughness, pattern, etc.). In some cases, the exterior surfaces of the housing members and the joint structures may be subjected to a two-stage blasting process to produce the target surface finish. 
       FIG. 1B  illustrates a back side of the device  100 . The device  100  may include a back or rear cover  132  coupled to the housing  104  and defining at least a portion of the exterior rear surface of the device  100 . The rear cover  132  may include a substrate formed of glass, though other suitable materials may alternatively be used (e.g., plastic, sapphire, ceramic, glass-ceramic, etc.). The rear cover  132  may include one or more decorative layers on the exterior or interior surface of the substrate. For example, one or more opaque layers may be applied to the interior surface of the substrate (or otherwise positioned along the interior surface of the substrate) to provide a particular appearance to the back side of the device  100 . The opaque layer(s) may include a sheet, ink, dye, or combinations of these (or other) layers, materials, or the like. In some cases the opaque layer(s) have a color that substantially matches a color of the housing  104  (e.g., the exterior surfaces of the housing members and the joint structures). The device  100  may include a wireless charging system, whereby the device  100  can be powered and/or its battery recharged by an inductive (or other electromagnetic) coupling between a charger and a wireless charging system within the device  100 . In such cases, the rear cover  132  may be formed of a material that allows and/or facilitates the wireless coupling between the charger and the wireless charging system (e.g., glass). 
     The device  100  may also include a sensor array  134 , which may include various types of sensors, including one or more rear-facing cameras, depth sensing devices, flashes, microphones, and the like. The sensor array  134  may be at least partially defined by a protrusion  137  that extends from the rear of the device  100 . The protrusion  137  may define a portion of the rear exterior surface of the device  100 . In some cases, the protrusion  137  may be formed by attaching a piece of material (e.g., glass) to another piece of material (e.g., glass). In other cases, the rear cover  132  may include a monolithic structure, and the protrusion  137  may be part of the monolithic structure. For example, the rear cover  132  may include a monolithic glass structure (or glass ceramic structure) that defines the protrusion  137  as well as the surrounding area. In such cases, the protrusion  137  may be an area of increased thickness of the monolithic structure, or it may be molded into a substantially uniform thickness monolithic structure (e.g., and may correspond to a recessed region along an interior side of the monolithic structure). 
     The device may also include, as part of the sensor array, one or more rear-facing devices  138 , which may include an ambient-light sensor (ALS), a microphone, and/or a depth sensing device that is configured to estimate a distance between the device  100  and a separate object or target. The sensor array  134  may include a camera with a 12 megapixel sensor, and a variable-focus lens with an aperture number of f/1.6. The sensor array  134  may also include multiple cameras including: a wide view camera having a 12 megapixel sensor and an aperture number of f/1.6; a super-wide camera having a 12 megapixel sensor and a wide field of view (e.g., 120° FOV) optical stack with an aperture number of f/2.4; and a telephoto lens having a 12 megapixel sensor with a 2× optical zoom optical stack having an aperture number ranging from f/2.0 to f/2.2. One or more of the cameras of the sensor array  134  may also include optical image stabilization, whereby the lens is dynamically moved relative to a fixed structure within the device  100  to reduce the effects of “camera shake” on images captured by the camera. The camera may also perform optical image stabilization by moving the image sensor relative to a fixed lens or optical assembly. 
     The sensor array  134 , along with associated processors and software, may provide several image-capture features. For example, the sensor array  134  may be configured to capture full-resolution video clips of a certain duration each time a user captures a still image. As used herein, capturing full-resolution images (e.g., video images or still images) may refer to capturing images using all or substantially all of the pixels of an image sensor, or otherwise capturing images using the maximum resolution of the camera (regardless of whether the maximum resolution is limited by the hardware or software). 
     The captured video clips may be associated with the still image. In some cases, users may be able to select individual frames from the video clip as the representative still image associated with the video clip. In this way, when the user takes a snapshot of a scene, the camera will actually record a short video clip (e.g., 1 second, 2 seconds, or the like), and the user can select the exact frame from the video to use as the captured still image (in addition to simply viewing the video clip as a video). 
     The sensor array  134  may also include one or more cameras having a high-dynamic-range (HDR) mode, in which the camera captures images having a dynamic range of luminosity that is greater than what is captured when the camera is not in the HDR mode. In some cases, the sensor array  134  automatically determines whether to capture images in an HDR or non-HDR mode. Such determination may be based on various factors, such as the ambient light of the scene, detected ranges of luminosity, tone, or other optical parameters in the scene, or the like. HDR images may be produced by capturing multiple images, each using different exposure or other image-capture parameters, and producing a composite image from the multiple captured images. 
     The sensor array  134  may also include or be configured to operate in an object detection mode, in which a user can select (and/or the device  100  can automatically identify) objects within a scene to facilitate those objects being processed, displayed, or captured differently than other parts of the scene. For example, a user may select (or the device  100  may automatically identify) a person&#39;s face in a scene, and the device  100  may focus on the person&#39;s face while selectively blurring the portions of the scene other than the person&#39;s face. Notably, features such as the HDR mode and the object detection mode may be provided with a single camera (e.g., a single lens and sensor). 
     The sensor array may include a flash  136  that is configured to illuminate a scene to facilitate capturing images with the sensor array  134 . The flash  136  may include one or more light sources, such as one or more light emitting diodes (e.g., 1, 2, 3, 4, or more LEDs). The flash  136 , in conjunction with the sensor array  134  or other systems of the device  100 , may adjust the color temperature of the light emitted by the light sources in order to match or otherwise adapt to a color temperature within a scene being captured. The device  100  may also be configured to operate the flash  136  and the shutter of the sensor array  134  to avoid consequences of flash “flicker.” For example, the device  100  may avoid capturing exposures during moments where the flash  136  is at a period of no or low illumination (e.g., which may be caused by discontinuous or pulsed operation of the LEDs). 
       FIGS. 1C and 1D  show another example electronic device  140  embodied as a mobile phone. The electronic device  140  may have many of the same or similar outward-facing components as the electronic device  100 . Accordingly, descriptions and details of such components from  FIGS. 1A-1B  (e.g., displays, buttons, switches, housings, covers, charging ports, joint structures, etc.) apply equally to the corresponding components shown in  FIGS. 1C and 1D . 
     While the device  100  in  FIG. 1B  is shown as including a sensor array  134  with two cameras, the device  140  as shown in  FIG. 1D  includes a sensor array  141  that includes three cameras (as shown, for example, in  FIGS. 3 and 5 , described herein). The sensor array  141  may be in a sensor array region that is defined by a protrusion  151  in a rear cover of the device  140 . The protrusion  151  may have the same or similar construction as the protrusion  137  in  FIG. 1B . 
     The sensor array  141  may also include a depth sensing device  149  that is configured to estimate a distance between the device and a separate object or target. For example, a first camera  142  may include a 12 megapixel sensor and a telephoto lens with a 2× or 2.5× optical zoom and an aperture number of f/2.0; a second camera  144  may include a 12 megapixel sensor and a wide angle lens having an aperture number of f/1.6; and a third camera  146  may include a 12 megapixel sensor and a super-wide camera with a wide field of view (e.g., 120° FOV) and an aperture number of f/2.4. The depth sensing device  149  may estimate a distance between the device and a separate object or target using lasers and time-of-flight calculations, or using other types of depth sensing components or techniques. One or more of the cameras of the sensor array  141  may also include optical image stabilization, whereby the lens is dynamically moved relative to a fixed structure within the device  100  to reduce the effects of “camera shake” on images captured by the camera. The camera may also perform optical image stabilization by moving the image sensor relative to a fixed lens or optical assembly. 
     The device  140  may also include a flash  148  that is configured to illuminate a scene to facilitate capturing images with the cameras of the sensor array  141 . The flash  148  is configured to illuminate a scene to facilitate capturing images with the sensor array  141 . The flash  148  may include one or more light sources, such as one or more light emitting diodes (e.g., 1, 2, 3, 4, or more LEDs). 
     The sensor array  141  may also include a microphone  150 . The microphone  150  may be acoustically coupled to the exterior environment through a hole defined in the rear cover of the device  140  (e.g., through the portion of the rear cover that defines the protrusion  151 ). 
     Other details about the sensor array, the individual cameras of the sensor array, and/or the flash described with respect to the device  100  may be applicable to the sensor array, the individual cameras, and/or the flash of the device  140 , and such details will not be repeated here to avoid redundancy. 
       FIG. 2  depicts an exploded view of an example electronic device. In particular,  FIG. 2  depicts an exploded view of a device  200 , showing various components of the device  200  and example arrangements and configurations of the components. The description of the various components and elements of device  100  of  FIGS. 1A and 1B  may also be applicable to the device  200  depicted in  FIG. 2 . A redundant description of some of the components is not repeated herein for clarity. 
     As shown in  FIG. 2 , the device  200  includes a cover  202  (e.g., a front cover), which may be formed of glass, ceramic, or other transparent substrate. In this example, the cover  202  may be formed from a glass or glass-ceramic material. A glass-ceramic material may include both amorphous and crystalline or non-amorphous phases of one or more materials and may be formulated to improve strength or other properties of the cover  202 . In some cases, the cover  202  may include a sheet of chemically strengthened glass or glass-ceramic having one or more coatings including an anti-reflective (AR) coating, an oleophobic coating, or other type of coating or optical treatment. In some cases, the cover  202  includes a sheet of material that is less than 1 mm thick. In some cases, the sheet of material is less than 0.80 mm. In some cases, the sheet of material is approximately 0.60 mm or less. The cover  202  may be chemically strengthened using an ion exchange process to form a compressive stress layer along exterior surfaces of the cover  202 . 
     The cover  202  extends over a substantial entirety of the front surface of the device and may be positioned within an opening defined by the housing  210 . As described in more detail below, the edges or sides of the cover  202  may be surrounded by a protective flange or lip of the housing  210  without an interstitial component between the edges of the cover  202  and the respective flanges of the housing  210 . This configuration may allow an impact or force applied to the housing  210  to be transferred to the cover  202  without directly transferring shear stress through the display  203  or frame  204 . 
     As shown in  FIG. 2 , the display  203  is attached to an internal surface of the cover  202 . The display  203  may include an edge-to-edge organic light emitting diode (OLED) display that measures 13.7 cm (5.4 inches) corner-to-corner. The perimeter or non-active area of the display  203  may be reduced to allow for very thin device borders around the active area of the display  203 . In some cases, the display  203  allows for border regions of 1.5 mm or less. In some cases, the display  203  allows for border regions of 1 mm or less. In one example implementation, the border region is approximately 0.9 mm. The display  203  may have a relatively high pixel density of approximately 450 pixels per inch (PPI) or greater. In some cases, the display  203  has a pixel density of approximately 475 PPI. The display  203  may have an integrated (on-cell) touch-sensing system. For example, an array of electrodes that are integrated into the OLED display may be time and/or frequency multiplexed in order to provide both display and touch-sensing functionality. The electrodes may be configured to detect a location of a touch, a gesture input, multi-touch input, or other types of touch input along the external surface of the cover  202 . In some cases, the display  203  includes another type of display element, such as a liquid-crystal display (LCD) without an integrated touch-sensing system. That is, the device  200  may include one or more touch- and/or force-sensing layers that are positioned between the display  203  and the cover  202 . 
     The display  203 , also referred to as a display stack, may include always-on-display (AOD) functionality. For example, the display  203  may be configurable to allow designated regions or subsets of pixels to be displayed when the device  200  is powered on such that graphical content is visible to the user even when the device  200  is in a low-power or sleep mode. This may allow the time, date, battery status, recent notifications, and other graphical content to be displayed in a lower-power or sleep mode. This graphical content may be referred to as persistent or always-on graphical output. While some battery power may be consumed when displaying persistent or always-on graphical output, the power consumption is typically less than during normal or full-power operation of the display  203 . This functionality may be enabled by only operating a subset of the display pixels and/or at a reduced resolution in order to reduce power consumption by the display  203 . 
     As shown in  FIG. 2 , the device  200  may also include a frame member  204 , also referred to simply as a frame  204 , that is positioned below the cover  202  and that extends around an outer periphery of the display  203 . A perimeter of the frame  204  may be attached to a lower or inner surface of the cover  202 . A portion of the frame  204  may extend below the display  203  and may attach the cover  202  to the housing  210 . Because the display  203  is attached to a lower or inner surface of the cover  202 , the frame  204  may also be described as attaching both the display  203  and the cover  202  to the housing  210 . The frame  204  may be formed of a polymer material, metal material, or combination of polymer and metal materials. The frame  204  may support elements of the display stack, provide anchor points for flexible circuits, and/or be used to mount other components and device elements. In some cases, the frame  204  includes one or more metal or conductive elements that provide shielding between device components, such as between the display stack (including display components and touch sensor components) and other components like the haptic actuator  222 , the speaker system  224 , and the like. 
     The cover  202 , display stack  203 , and frame member  204  may be part of a top module  201  of the device  200 . The top module  201  may be assembled as a subassembly, which may then be attached to a housing member. For example, as described herein, the display  203  may be attached to the cover  202  (e.g., via a transparent adhesive), and the frame member  204  may be attached (e.g., via adhesive) to the cover around a periphery of the display stack  203 . The top module  201  may then be attached to a housing member of the device  200  by mounting and adhering the frame member  204  to a ledge defined by the housing member. 
     As shown in  FIG. 2 , the device  200  also includes one or more cameras, light emitters, and/or sensing elements that are configured to transmit signals, receive signals, or otherwise operate along the front surface of the device. In this example, the device  200  includes a front camera  206  that includes a high-resolution camera sensor. The front camera  206  may have a 12 megapixel resolution sensor with optical elements that provide a fixed focus and an 85° field of view. The device  200  also includes a facial recognition sensor  252  that may be used to detect or capture a unique signature or bio-identifier (e.g., by projecting a pattern of dots onto a user&#39;s face and capturing an image of the user&#39;s face with the projected dots), which may be used to identify the user and unlock the device  200  or authorize functionality on the device  200  like the purchase of software apps or the use of payment functionality provided by the device  200 . 
     The device may also include one or more other sensors or elements that are integrated into a front-facing sensor array  250 . For example, the front-facing sensor array  250  may include a front light illuminator element for providing a flash or illumination for the front camera  206 . The front-facing sensor array  250  may also include an ambient light sensor (ALS) that is used to detect ambient light conditions for setting exposure aspects of the front camera  206 . The front-facing sensor array  250  may also include an antenna array that is configured to transmit and receive wireless communications along the front surface of the device  200 . The antenna array may include antenna elements that are configured to conduct a 5G wireless protocol that may include mm wave and/or 6 GHz communication signals. The antenna array may include multiple antenna elements and may be configured to use beam-forming and other similar techniques to facilitate 5G wireless communication. As used herein, an antenna element may refer to a component that is configured (e.g., tuned) to resonate at a particular frequency or frequency band. Antenna elements may be formed from any suitable component or material, such as conductors (e.g., wires, metallic traces, metal housing segments), ceramics, or the like. 
       FIG. 2  also illustrates one or more cameras, light emitters, and/or sensing elements that are configured to transmit signals, receive signals, or otherwise operate along the rear surface of the device. As depicted in  FIG. 2 , these elements may be part of a sensor array  260 . In this example, the sensor array  260  includes a first camera  261  having a 12 megapixel image sensor and a wide angle lens with an aperture number of f/1.6. The first camera  261  also includes a dual photodiode sensor having an APS+ sensor format. The sensor array  260  also includes a second camera  262  having a 12 megapixel image sensor and a super-wide angle lens (120° FOV) with an aperture number of f/2.4. The sensor array  260  also includes a light illuminator that may be used as a flash for photography or as an auxiliary light source (e.g., a flashlight). The sensor array  260  also features an integrated chassis design that minimizes space while providing the precision alignment required for multiple high-resolution cameras. In some cases, the sensor array  260  also includes a microphone, an ambient light sensor, and other sensors that are adapted to sense along the rear surface of the device  200 . 
     As shown in  FIG. 2 , the cameras  261  and  262  may be aligned with camera covers  263  and  264 , respectively. The covers  263 ,  264  may be formed from a glass, glass-ceramic, or sapphire material and may provide a clear window through which the cameras  261 ,  262  are able to capture a photographic image. In other cases, the covers  263 ,  264  are optical lenses that filter, magnify, or otherwise condition light received by the respective camera  261 ,  262 . The other sensing or transmitting elements of the sensor array  260  may transmit and/or receive signals through a region of the rear cover  272  or through a separate cover that is coupled to the rear cover  272 . As shown in  FIG. 2 , the covers  263 ,  264  may extend beyond the exterior surface of the cover  272 , and may define a recess along the interior side of the cover  272 , such that the lens or other element of the cameras  261  and  262  can extend into the respective recesses. In this way, the device  200  may accommodate a larger lens or other elements of the cameras  261  and  262  than would be possible if the recess were not provided. 
     The device  200  also includes a battery  230 . The battery  230  provides electrical power to the device  200  and its various systems and components. The battery  230  may include a 4.45 V lithium ion battery that is encased in a foil or other enclosing element (e.g., a pouch). The battery  230  may be attached to the device  200  (e.g., to the chassis  219 ) with one or more adhesives and/or other attachment techniques. In one example, the battery  230  may be attached to the chassis  219 , or another structure of the device  200 , with a two-layer adhesive, where a first adhesive is adhered to the battery  230  and to a second adhesive, and the second adhesive is bonded to the first adhesive and to the chassis  219  (or other structure of the device  200 ). The first and second adhesives may have different properties, such as different stiffness (e.g., Young&#39;s modulus), different adhesive properties, or the like. For example, in some cases, the first adhesive is configured to adhere to the material of the battery  230  (e.g., with a bond strength above a threshold value), while the second adhesive is configured to adhere to the chassis  219  or other structure of the device (e.g., with a bond strength above the threshold value). In such cases, the first adhesive may not form a sufficiently strong bond with the chassis  219 , and the second adhesive may not form a sufficiently strong bond with the battery  230 , though the first and second adhesives may form a sufficiently strong bond with one another. Accordingly, by using the two different adhesives (e.g., in the layered configuration described) to ultimately secure the battery  230  to the chassis  219 , the overall strength and/or security of the attachment may be greater than if a single adhesive were used. 
     The battery  230  may be recharged via the charging port  232  (e.g., from a power cable plugged into the charging port  232 ), and/or via a wireless charging system  240 . The battery  230  may be coupled to the charging port  232  and/or the wireless charging system  240  via battery control circuitry that controls the power provided to the battery and the power provided by the battery to the device  200 . The battery  230  may include one or more lithium ion battery cells or any other suitable type of rechargeable battery element. 
     The charging system  240  may include a coil that inductively couples to an output or transmitting coil of a wireless charger. The coil may provide current to the device  200  to charge the battery  230  and/or power the device. In this example, the charging system  240  includes a coil assembly  242  that includes multiple wraps of a conductive wire or other conduit that is configured to produce a (charging) current in response to being placed in an inductive charging electromagnetic field produced by a separate wireless charging device or accessory. The coil assembly  242  also includes an array of magnetic elements that are arranged in a circular or radial pattern. The magnetic elements may help to locate the device  200  with respect to a separate wireless charging device or other accessory. In some implementations, the array of magnets also help to radially locate, orient, or “clock” the device  200  with respect to the separate wireless charging device or other accessory. For example, the array of magnets may include multiple magnetic elements having alternating magnetic polarity that are arranged in a radial pattern. The magnetic elements may be arranged to provide a magnetic coupling to the separate charging device in a particular orientation or set of discrete orientations to help locate the device  200  with respect to the separate charging device or other accessory. This functionality may be described as self-aligning or self-locating wireless charging. As shown in  FIG. 2 , the device  200  also includes a magnetic fiducial  244  for helping to locate the separate wireless charging device or accessory. In one example, the magnetic fiducial  244  is adapted to magnetically couple to a cable or power cord of the separate wireless charging device or other accessory. By coupling to the cable or power cord, the rotational alignment of the device  200  and the separate wireless charging device or other accessory may be maintained with respect to an absolute or single position. Also, by magnetically coupling the cable or cord to the rear surface of the device  200 , the charging device or other accessory may be more securely coupled to the device  200 . 
     The device  200  may also include a speaker system  224 . The speaker system  224  may be positioned in the device  200  so that a respective speaker port  225  is aligned with or otherwise proximate an audio output of the speaker system  224 . Accordingly, sound that is output by the speaker system  224  exits the housing  210  via the respective speaker port  225 . The speaker system  224  may include a speaker positioned in a housing that defines a speaker volume (e.g., an empty space in front of or behind a speaker diaphragm). The speaker volume may be used to tune the audio output from the speaker and optionally mitigate destructive interference of the sound produced by the speaker. The speaker system  224  may include left and right speakers that are aligned with left and right speaker ports  225 , respectively, in order to produce stereo sound. 
     The device  200  may also include a haptic actuator  222 . The haptic actuator  222  may include a movable mass and an actuation system that is configured to move the mass to produce a haptic output. The actuation system may include one or more coils and one or more magnets (e.g., permanent and/or electromagnets) that interact to produce motion. The magnets may be or may include recycled magnetic material. As described herein, the haptic actuator  222  may have a profile or enclosure shape that facilitates physical integration with the battery  230  and other components of the device  200  in order to minimize space and/or maximize the size of the battery. 
     When the coil(s) are energized, the coil(s) may cause the mass to move, which results in a force being imparted on the device  200 . The motion of the mass may be configured to cause a vibration, pulse, tap, or other tactile output detectable via an exterior surface of the device  200 . The haptic actuator  222  may be configured to move the mass linearly, though other movements (e.g., rotational) are also contemplated. Other types of haptic actuators may be used instead of or in addition to the haptic actuator  222 . 
     The device  200  also includes a logic board  220  (also referred to herein as a circuit board assembly). The logic board  220  may include a substrate, and processors, memory, and other circuit elements coupled to the substrate. The logic board  220  may include multiple circuit substrates that are stacked and coupled together in order to maximize the area available for electronic components and circuitry in a compact form factor. The logic board  220  may include provisions for a subscriber identity module (SIM). The logic board  220  may include electrical contacts and/or a SIM tray assembly for receiving a physical SIM card and/or the logic board  220  may include provisions for an electronic SIM. The logic board  220  may be wholly or partially encapsulated to reduce the chance of damage due to an ingress of water or other fluid. 
     The logic board  220  may also include a liquid detection circuit  227  that is located proximate to the charging opening  226  or other opening in the housing  210 . The liquid detection circuit  227  may include a resistive or conductive sensor that is configured to electrically detect moisture above a given threshold and transmit a signal to the processor in order to record a liquid exposure event. The liquid detection circuit  227  may also include a visual element that changes color or provides some other visual indicia when exposed to moisture above a certain threshold. In some cases, the liquid detection circuit  227  is positioned within a sealed internal volume of a waterproof or water resistant device and is configured to detect liquid ingress due to a mechanical breach of the housing  210  or physical damage to the device  200 . 
     The logic board  220  may also include wireless communications circuitry, which may be coupled to and/or otherwise use the housing members  211 ,  212 ,  213 ,  214 ,  215 , or  216  (or portions thereof) as radiating members to provide wireless communications. The logic board  220  may also include components such as accelerometers, gyroscopes, near-field-communications circuitry and/or antennas, compasses, and the like. 
     The housing  210  may also include a chassis  219 , which may be attached to the housing  210 . The chassis  219  may be formed of metal, and may act as a structural mounting point for components of the device  200 . The chassis  219  may define an opening that corresponds to the size of the coil assembly  242  of the wireless charging system  240 , such that the chassis  219  does not shield the wireless coil assembly  242  or otherwise negatively affect the inductive coupling between the coil of the charging system  240  and an external wireless charger or accessory. 
     As shown in  FIG. 2 , the housing may include a cover  272  (e.g., rear or back cover) that may define a substantial entirety of the rear surface of the device  200 . The cover  272  may be formed from a glass (or glass-ceramic) substrate having portions that are less than 1 mm thick. In some cases, the sheet substrate has portions that are less than 0.80 mm. In some cases, the glass substrate has portions that are approximately 0.60 mm or less. The cover  272  may have a uniform thickness or, in some cases, may have a thickened or raised portion that surrounds the camera covers  263 ,  264 . The cover  272  may be machined (e.g., ground) into a final shape before being polished and/or textured to provide the desired surface finish. The texture may be specially configured to provide a matte appearance while also being resistant to collecting a buildup of skin, lint, or other debris. A series of cosmetic layers may be formed along the inner surface of the cover  272  to provide a desired optical effect and final color of the device  200 . 
     Similar to as described above with respect to cover  202 , the cover  272  may be positioned at least partially within an opening defined in the housing  210 . Also similar to as described above with respect to cover  202 , the edges or sides of the cover  272  may be surrounded by a protective flange or lip of the housing  210  without an interstitial component between the edges of the cover  272  and the respective flanges of the housing  210 . The cover  272  is typically chemically strengthened using an ion exchange process to form a compressive stress layer along exterior surfaces of the cover  272 . 
     As described above, the housing  210  may include housing members  211 ,  212 ,  213 ,  214 ,  215 , and  216  structurally joined together via joint structures  218 .  FIG. 2  illustrates how the joint structures  218  may extend over inner surfaces of the housing members. More particularly, a portion of the joint structures  218  may contact, cover, encapsulate, and/or engage with retention features of the housing members that extend from the inner surfaces of the housing members. 
     Housing members  211 ,  212 ,  213 ,  214 ,  215 , and  216  may also be referred to herein as housing segments and may be formed from aluminum, stainless steel, or other metal or metal alloy material. As described herein, the housing members  211 ,  212 ,  213 ,  214 ,  215 , and  216  may provide a robust and impact resistant sidewall for the device  200 . In the present example, the housing members  211 ,  212 ,  213 ,  214 ,  215 , and  216  define a flat sidewall that extends around the perimeter of the device  200 . The flat sidewall may include rounded or chamfered edges that define the upper and lower edges of the sidewall of the housing  210 . The housing members  211 ,  212 ,  213 ,  214 ,  215 , and  216  may each have a flange portion or lip that extends around and at least partially covers a respective side of the front and rear covers  202 ,  272 . There may be no interstitial material or elements between the flange portion or lip and the respective side surface of the front and rear covers  202 ,  272 . This may allow forces or impacts that are applied to the housing  210  to be transferred to the front and rear covers  202 ,  272  without affecting the display or other internal structural elements, which may improve the drop performance of the device  200 . 
     As shown in  FIG. 2 , the device  200  includes multiple antennas that may be adapted to conduct wireless communication using a 5G communication protocol. In particular, the device  200  may include a (front-fired) antenna array  286  that is positioned near the earpiece of the device  200  and configured to transmit and receive wireless communication signals through the cover  202 . The device  200  may also include a (side-fired) antenna array  282  that is configured to transmit and receive wireless communication signals through an antenna window  283  or waveguide formed along or otherwise integrated with the sidewall of the housing  210 . The side-fired antenna array  282  may be coupled to the logic board  220  via a flexible circuit element or other conductive connection, as described herein. The device  200  may also include a (rear-fired) antenna array  284  that may be configured to transmit and receive wireless communication signals through the cover  272 . The antenna array  284  may be attached to a back or bottom surface of the logic board  220 . Each of the antenna arrays  282 ,  284 ,  286  may be adapted to conduct millimeter wave 5G communications and may be adapted to use or be used with beam-forming or other techniques to adapt signal reception depending on the use case. The device  200  may also include multiple antennas for conducting multiple-in multiple-out (MIMO) wireless communications schemes, including 4G, 4G LTE, and/or 5G MIMO communication protocols. As described herein, one or more of the housing members  211 ,  212 ,  213 ,  214 ,  215 , and  216  may be adapted to operate as antennas for a MIMO wireless communication scheme (or other wireless communication scheme). 
       FIG. 3  depicts an exploded view of an example electronic device. In particular,  FIG. 3  depicts an exploded view of a device  300 , showing various components of the device  300  and example arrangements and configurations of the components. The description of the various components and elements of device  100  of  FIGS. 1A and 1B  may also be applicable to the device  300  depicted in  FIG. 3 . A redundant description of some of the components is not repeated herein for clarity. 
     As shown in  FIG. 3 , the device  300  includes a cover  302  (e.g., a front cover), which may be formed of glass, ceramic, or other transparent substrate. In this example, the cover  302  may be formed from a glass or glass-ceramic material. A glass-ceramic material may include both amorphous and crystalline or non-amorphous phases of one or more materials and may be formulated to improve strength or other properties of the cover  302 . In some cases, the cover  302  may include a sheet of chemically strengthened material having one or more coatings including an anti-reflective (AR) coating, an oleophobic coating, or other type of coating or optical treatment. In some cases, the cover  302  includes a sheet of material that is less than 1 mm thick. In some cases, the sheet of material is less than 0.80 mm. In some cases, the sheet of material is approximately 0.60 mm or less. The cover  302  may be chemically strengthened using an ion exchange process to form a compressive stress layer along exterior surfaces of the cover  302 . 
     The cover  302  extends over a substantial entirety of the front surface of the device and may be positioned within an opening defined by the housing  310 . As described in more detail below, the edges or sides of the cover  302  may be surrounded by a protective flange or lip of the housing  310  without an interstitial component between the edges of the cover  302  and the respective flanges of the housing  310 . This configuration may allow an impact or force applied to the housing  310  to be transferred to the cover  302  without directly transferring shear stress through the display  303  or frame  304 . 
     As shown in  FIG. 3 , the display  303  is coupled to an internal surface of the cover  302 . In this example, the display stack includes a display  303  (also referred to as a display element) and a touch-sensing layer  305 , which is positioned between the display  303  and the cover  302 . The display  303  may include an edge-to-edge organic light emitting diode (OLED) display that measures 15.4 cm (6.1 inches) corner-to-corner. The perimeter or non-active area of the display  303  may be reduced to allow for very thin device borders around the active area of the display  303 . In some cases, the display  303  allows for border regions of 1.5 mm or less. In some cases, the display  303  allows for border regions of 1 mm or less. In one example implementation, the border region is approximately 0.9 mm. The display  303  may have a relatively high pixel density of approximately 450 pixels per inch (PPI) or greater. In some cases, the display  303  has a pixel density of approximately 460 PPI. 
     As shown in  FIG. 3 , the display stack includes both a display (element)  303  and a separate touch-sensing layer  305 , and includes an array of capacitive electrodes that are configured to sense the presence and location of one or more touches along the external surface of the cover  302 . The electrodes of the touch-sensing layer  305  may be configured to detect a location of a touch, a gesture input, multi-touch input, or other types of touch input along the external surface of the cover  302 . In some cases, the touch-sensing layer  305  is coupled to or has an integrated flex circuit that extends from one or more of the long sides of the touch-sensing layer  305 , which may reduce the border around the display  303 . As with the previous example described above with respect to  FIG. 2 , the display  303  may have an integrated (on-cell) touch-sensing system. For example, an array of electrodes that are integrated into the OLED display may be time and/or frequency multiplexed in order to provide both display and touch-sensing functionality. In some cases, the display  303  includes another type of display element, such as a liquid-crystal display (LCD). 
     The display  303  may include always-on-display (AOD) functionality. For example, the display  303  may be configurable to allow designated regions or subsets of pixels to be displayed when the device  300  is powered on such that graphical content is visible to the user even when the device  300  is in a low-power or sleep mode. This may allow the time, date, battery status, recent notifications, and other graphical content to be displayed in a lower-power or sleep mode. This graphical content may be referred to as persistent or always-on graphical output. While some battery power may be consumed when displaying persistent or always-on graphical output, the power consumption is typically less than during normal or full-power operation of the display  303 . This functionality may be enabled by only operating a subset of the display pixels and/or at a reduced resolution in order to reduce power consumption by the display  303 . 
     As shown in  FIG. 3 , the device  300  may also include a frame  304  that is positioned below the cover  302  and that extends around an outer periphery of the display  303 . A perimeter of the frame  304  may be attached to a lower or inner surface of the cover  302 . A portion of the frame  304  may extend below the display  303  and may attach the cover  302  to the housing  310 . Because the display  303  is attached to a lower or inner surface of the cover  302 , the frame  304  may also be described as attaching both the display  303  and the cover  302  to the housing  310 . The frame  304  may be formed of a polymer material, metal material, or combination of polymer and metal materials. The frame  304  may support elements of the display stack, provide anchor points for flexible circuits, and/or be used to mount other components and device elements. In some cases, the frame  304  includes one or more metal or conductive elements that provide shielding between device components, such as between the display stack (including display components and touch sensor components) and other components like the haptic actuator  322 , the speaker system  324 , and the like. 
     The cover  302 , touch-sensing layer  305 , display  303 , and frame member  304  may be part of a top module  301  of the device  300 . The top module  301  may be assembled as a subassembly, which may then be attached to a housing member. For example, as described herein, the display  303  and touch-sensing layer  305  may be attached to the cover  302  (e.g., via a transparent adhesive), and the frame member  304  may be attached (e.g., via adhesive) to the cover around a periphery of the display  303 . The top module  301  may then be attached to a housing member of the device  300  by mounting and adhering the frame member  304  to a ledge defined by the housing member. 
     As shown in  FIG. 3 , the device  300  also includes one or more cameras, light emitters, and/or sensing elements that are configured to transmit signals, receive signals, or otherwise operate along the front surface of the device. In this example, the device  300  includes a front camera  306  that includes a high-resolution camera sensor. The front camera  306  may have a 12 megapixel resolution sensor with optical elements that provide a fixed focus and an 85° field of view. The front camera  306  may have an aperture number of f/2.2. The device  300  also includes a facial recognition sensor  352  that includes a depth sensor that includes an infrared light projector and an infrared light sensor that are configured to sense an array of depth points or regions along the face of the user. The array of depth points may be characterized as a unique signature or bio-identifier, which may be used to identify the user and unlock the device  300  or authorize functionality on the device  300  like the purchase of software apps or the use of payment functionality provided by the device  300 . 
     The device may also include one or more other sensors or elements that are integrated into a front-facing sensor array  350 . For example, the front-facing sensor array  350  may include a front light illuminator element for providing a flash or illumination for the front camera  306 . The front-facing sensor array  350  may also include an ambient light sensor (ALS) that is used to detect ambient light conditions for setting exposure aspects of the front camera  306 . The front-facing sensor array  350  may also include an antenna array that is configured to transmit and receive wireless communications along the front surface of the device  300 . The antenna array may include elements that are configured to conduct a 5G wireless protocol that may include mm wave and/or 6 GHz communication signals. The antenna array may include multiple elements and may be configured to use or be used with beam-forming and other similar techniques to facilitate 5G wireless communication. 
       FIG. 3  also illustrates one or more cameras, light emitters, and/or sensing elements that are configured to transmit signals, receive signals, or otherwise operate along the rear surface of the device. As depicted in  FIG. 3 , these elements may be integrated in a sensor array  360 . In this example, the sensor array  360  includes a first camera  361  having a 12 megapixel image sensor and a wide angle lens with an aperture number of f/1.6. The first camera  361  also includes a dual photodiode sensor having an APS+ sensor format. The sensor array  360  also includes a second camera  362  having a 12 megapixel image sensor and a super-wide angle lens (120° FOV) with an aperture number of f/2.4. The sensor array  360  may also include a third camera  363  having a 12 megapixel image sensor and a telephoto optical lens assembly that enables 2× optical zoom. The third camera  363  may also have an aperture number of f/2.0. 
     The sensor array  360  also includes a light illuminator that may be used as a flash for photography or as an auxiliary light source (e.g., a flashlight). The sensor array  360  also features an integrated chassis design that minimizes space while providing the precision alignment required for multiple high-resolution cameras. In some cases, the sensor array  360  also includes a microphone, an ambient light sensor, and other sensors that are adapted to sense along the rear surface of the device  300 . 
     The sensor array  360  may also include a depth sensor  365  that is able to estimate a distance to objects positioned behind the device  300 . The depth sensor  365  may include an optical sensor that uses time-of-flight or other optical effect to measure a distance between the device  300  and an external object. The depth sensor  365  may include one or more optical emitters that are adapted to emit one or more beams of light, which may be used to estimate the distance. In some cases, the one or more beams of light are coherent light beams having a substantially uniform wavelength/frequency (e.g., laser beams). A coherent light source may facilitate depth measurements using a time of flight, phase shift, or other optical effect. In some cases, the depth sensor  365  uses a sonic output, a radio output, or other type of output that may be used to measure the distance between the device  300  and one or more external objects. 
     As shown in  FIG. 3 , the cameras  361 ,  362 ,  363  may be aligned with camera covers  366 ,  367 ,  368 , respectively. The covers  366 ,  367 ,  368  may be formed from a glass or sapphire material and may provide a clear window through which the cameras  361 ,  362 ,  363  are able to capture a photographic image. In other cases, the covers  366 ,  367 ,  368  are optical lenses that filter, magnify, or otherwise condition light received by the respective camera  361 ,  362 ,  363 . The other sensing or transmitting elements of the sensor array  360  may transmit and/or receive signals through a region of the rear cover  372  or through a separate cover (e.g.,  369 ) that is coupled to the rear cover  372 . As shown in  FIG. 3 , the covers  366 ,  367 ,  368  may extend beyond the exterior surface of the cover  372 , and may define a recess along the interior side of the cover  372 , such that the lens or other element of the cameras  361 ,  362 ,  363  can extend into the respective recesses. In this way, the device  300  may accommodate a larger lens or other elements of the cameras  361 ,  362 ,  363  than would be possible if the recess were not provided. 
     The device  300  also includes a battery  330 . The battery  330  provides electrical power to the device  300  and its various systems and components. The battery  330  may include a 4.45 V lithium ion battery that is encased in a foil or other enclosing element. The battery  330  may include a rolled electrode configuration, sometimes referred to as “jelly roll” or folded electrode configuration. The battery  330  may be recharged via the charging port  332  (e.g., from a power cable plugged into the charging port  332 ), and/or via a wireless charging system  340 . The battery  330  may be coupled to the charging port  332  and/or the wireless charging system  340  via battery control circuitry that controls the power provided to the battery and the power provided by the battery to the device  300 . The battery  330  may include one or more lithium ion battery cells or any other suitable type of rechargeable battery element. 
     The charging system  340  may include a coil that inductively couples to an output or transmitting coil of a wireless charger. The coil may provide current to the device  300  to charge the battery  330  and/or power the device. In this example, the charging system  340  includes a coil assembly  342  that includes multiple wraps of a conductive wire or other conduit that is configured to produce a (charging) current in response to being placed in an inductive charging electromagnetic field produced by a separate wireless charging device or accessory. The coil assembly  342  also includes an array of magnetic elements that are arranged in a circular or radial pattern. The magnetic elements may help to locate the device  300  with respect to a separate wireless charging device or other accessory. In some implementations, the array of magnets also help to radially locate, orient, or “clock” the device  300  with respect to the separate wireless charging device or other accessory. For example, the array of magnets may include multiple magnetic elements having alternating magnetic polarity that are arranged in a radial pattern. The magnetic elements may be arranged to provide a magnetic coupling to the separate charging device in a particular orientation or set of discrete orientations to help locate the device  300  with respect to the separate charging device or other accessory. This functionality may be described as self-aligning or self-locating wireless charging. As shown in  FIG. 3 , the device  300  also includes a magnetic fiducial  344  for helping to locate the separate wireless charging device or accessory. In one example, the magnetic fiducial  344  is adapted to magnetically couple to a cable or power cord of the separate wireless charging device or other accessory. By coupling to the cable or power cord, the rotational alignment of the device  300  and the separate wireless charging device or other accessory may be maintained with respect to an absolute or single position. Also, by magnetically coupling the cable or cord to the rear surface of the device  300 , the charging device or other accessory may be more securely coupled to the device  300 . 
     In some implementations, the charging system  340  includes an antenna or other element that detects the presence of a charging device or other accessory. In some cases, the charging system includes a near-field communications (NFC) antenna that is adapted to receive and/or send wireless communications between the device  300  and the wireless charger or other accessory. In some cases, the device  300  is adapted to perform wireless communications to detect or sense the presence of the wireless charger or other accessory without using a dedicated NFC antenna. The communications may also include information regarding the status of the device, the amount of charge held by the battery  330 , and/or control signals to increase charging, decrease charging, start charging and/or stop charging for a wireless charging operation. 
     The device  300  may also include a speaker system  324 . The speaker system  324  may be positioned in the device  300  so that a respective speaker port  325  is aligned with or otherwise proximate an audio output of the speaker system  324 . Accordingly, sound that is output by the speaker system  324  exits the housing  310  via the respective speaker port  325 . The speaker system  324  may include a speaker positioned in a housing that defines a speaker volume (e.g., an empty space in front of or behind a speaker diaphragm). The speaker volume may be used to tune the audio output from the speaker and optionally mitigate destructive interference of the sound produced by the speaker. The speaker system  324  may include left and right speakers that are aligned with left and right speaker ports  325 , respectively, in order to produce stereo sound. 
     The device  300  may also include a haptic actuator  322 . The haptic actuator  322  may include a movable mass and an actuation system that is configured to move the mass to produce a haptic output. The actuation system may include one or more coils and one or more magnets (e.g., permanent and/or electromagnets) that interact to produce motion. The magnets may be or may include recycled magnetic material. As described herein, the haptic actuator  322  may have a profile or enclosure shape that facilitates physical integration with the battery  330  and other components of the device  300  in order to minimize space and/or maximize the size of the battery. 
     When the coil(s) are energized, the coil(s) may cause the mass to move, which results in a force being imparted on the device  300 . The motion of the mass may be configured to cause a vibration, pulse, tap, or other tactile output detectable via an exterior surface of the device  300 . The haptic actuator  322  may be configured to move the mass linearly, though other movements (e.g., rotational) are also contemplated. Other types of haptic actuators may be used instead of or in addition to the haptic actuator  322 . 
     The device  300  also includes a logic board  320 . The logic board  320  may include a substrate, and processors, memory, and other circuit elements coupled to the substrate. The logic board  320  may include multiple circuit substrates that are stacked and coupled together in order to maximize the area available for electronic components and circuitry in a compact form factor. The logic board  320  may include provisions for a subscriber identity module (SIM). The logic board  320  may include electrical contacts and/or a SIM tray assembly for receiving a physical SIM card and/or the logic board  320  may include provisions for an electronic SIM. The logic board  320  may be wholly or partially encapsulated to reduce the chance of damage due to an ingress of water or other fluid. 
     The logic board  320  may also include a liquid detection circuit  327  that is located proximate to the charging opening  326  or other opening in the housing  310 . The liquid detection circuit  327  may include a resistive or conductive sensor that is configured to electrically detect moisture above a given threshold and transmit a signal to the processor in order to record a liquid exposure event. The liquid detection circuit  327  may also include a visual element that changes color or provides some other visual indicia when exposed to moisture above a certain threshold. In some cases, the liquid detection circuit  327  is positioned within a sealed internal volume of a waterproof or water resistant device and is configured to detect liquid ingress due to a mechanical breach of the housing  310  or physical damage to the device  300 . 
     The logic board  320  may also include wireless communications circuitry, which may be coupled to and/or otherwise use the housing members  311 ,  312 ,  313 ,  314 ,  315 , or  316  (or portions thereof) as radiating members or structures to provide wireless communications. The logic board  320  may also include components such as accelerometers, gyroscopes, near-field communications circuitry and/or antennas, compasses, and the like. In some implementations, the logic board  320  may include a magnetometer that is adapted to detect and/or locate an accessory. For example, the magnetometer may be adapted to detect a magnetic (or non-magnetic) signal produced by an accessory of the device  300  or other device. The output of the magnetometer may include a direction output that may be used to display a directional indicia or other navigational guidance on the display  303  in order to guide the user toward a location of the accessory or other device. 
     The logic board  320  may also include one or more pressure transducers that may be operable to detect changes in external pressure in order to determine changes in altitude or height. The pressure sensors may be externally ported and/or positioned within a water-sealed internal volume of the housing  310 . The output of the pressure sensors may be used to track flights of stairs climbed, a location (e.g., a floor) of a multi-story structure, movement performed during an activity in order to estimate physical effort or calories burned, or other relative movement of the device  300 . 
     The logic board  320  may also include global position system (GPS) electronics that may be used to determine the location of the device  300  with respect to one or more satellites (e.g., a Global Navigation Satellite System (SNSS)) in order to estimate an absolution location of the device  300 . In some implementations, the GPS electronics are operable to utilize dual frequency bands. For example, the GPS electronics may use L1 (L1C), L2 (L2C), L5, L1+L5, and other GPS signal bands in order to estimate the location of the device  300 . 
     As shown in  FIG. 3 , the housing may include a cover  372  (e.g., rear or back cover) that may define a substantial entirety of the rear surface of the device  300 . The cover  372  may be formed from a glass substrate having portions that are less than 1 mm thick. In some cases, the sheet substrate has portions that are less than 0.80 mm. In some cases, the glass substrate has portions that are approximately 0.60 mm or less. The cover  372  may have a uniform thickness or, in some cases, may have a thickened or raised portion that surrounds the camera covers  366 ,  367 ,  368 . The cover  372  may be machined (e.g., ground) into a final shape before being polished and/or textured to provide the desired surface finish. The texture may be specially configured to provide a matte appearance while also being resistant to collecting a buildup of skin, lint, or other debris. A series of cosmetic layers may be formed along the inner surface of the cover  372  to provide a desired optical effect and final color of the device  300 . 
     Similar to as described above with respect to cover  302 , the cover  372  may be positioned at least partially within an opening defined in the housing  310 . Also similar to as described above with respect to cover  302 , the edges or sides of the cover  372  may be surrounded by a protective flange or lip of the housing  310  without an interstitial component between the edges of the cover  372  and the respective flanges of the housing  310 . The cover  372  is typically chemically strengthened using an ion exchange process to form a compressive stress layer along exterior surfaces of the cover  372 . 
     As described above, the housing  310  may include housing members  311 ,  312 ,  313 ,  314 ,  315 , and  316  structurally joined together via joint structures  318 .  FIG. 3  illustrates how the joint structures  318  may extend over inner surfaces of the housing members. More particularly, a portion of the joint structures  318  may contact, cover, encapsulate, and/or engage with retention features of the housing members that extend from the inner surfaces of the housing members. 
     Housing members  311 ,  312 ,  313 ,  314 ,  315 , and  316  may also be referred to herein as housing segments and may be formed from aluminum, stainless steel, or other metal or metal alloy material. As described herein, the housing members  311 ,  312 ,  313 ,  314 ,  315 , and  316  may provide a robust and impact resistant sidewall for the device  300 . In the present example, the housing members  311 ,  312 ,  313 ,  314 ,  315 , and  316  define a flat sidewall that extends around the perimeter of the device  300 . The flat sidewall may include rounded or chamfered edges that define the upper and lower edges of the sidewall of the housing  310 . The housing members  311 ,  312 ,  313 ,  314 ,  315 , and  316  may each have a flange portion or lip that extends around and at least partially covers a respective side of the front and rear covers  302 ,  372 . There may be no interstitial material or elements between the flange portion or lip and the respective side surface of the front and rear covers  302 ,  372 . This may allow forces or impacts that are applied to the housing  310  to be transferred to the front and rear covers  302 ,  372  without affecting the display or other internal structural elements, which may improve the drop performance of the device  300 . 
     As shown in  FIG. 3 , the device  300  includes multiple antennas that may be adapted to conduct wireless communication using a 5G communication protocol. In particular, the device  300  may include a (front-fired) antenna array  386  that is positioned near the earpiece of the device  300  and configured to transmit and receive wireless communication signals through the cover  302 . The device  300  may also include a (side-fired) antenna array  382  that is configured to transmit and receive wireless communication signals through an antenna window  383  or waveguide formed along or otherwise integrated with the side wall of the housing  310 . The side-fired antenna array  382  may be coupled to the logic board  320  via a flexible circuit element or other conductive connection, as described herein. The device  300  may also include a (rear-fired) antenna array  384  that may be configured to transmit and receive wireless communication signals through the cover  372 . The (rear-fired) antenna array  384  may be attached to a back or bottom surface of the logic board  320 . Each of the antenna arrays  382 ,  384 ,  386  may be adapted to conduct millimeter wave 5G communications and may be adapted to use or be used with beam-forming or other techniques to adapt signal reception depending on the use case. The device  300  may also include multiple antennas for conducting multiple-in multiple-out (MIMO) wireless communications schemes, including 4G, 4G LTE, and/or 5G MIMO communication protocols. As described herein, one or more of the housing members  311 ,  312 ,  313 ,  314 ,  315 , and  316  may be adapted to operate as antennas for a MIMO wireless communication scheme (or other wireless communication scheme). 
       FIG. 4  depicts an exploded view of an example electronic device. In particular,  FIG. 4  depicts an exploded view of a device  400 , showing various components of the device  400  and example arrangements and configurations of the components. The description of the various components and elements of device  100  of  FIGS. 1A and 1B  may also be applicable to the device  400  depicted in  FIG. 4 . A redundant description of some of the components is not repeated herein for clarity. 
     As shown in  FIG. 4 , the device  400  includes a cover  402  (e.g., a front cover), which may be formed of glass, ceramic, or other transparent substrate. In this example, the cover  402  may be formed from a glass or glass-ceramic material. A glass-ceramic material may include both amorphous and crystalline or non-amorphous phases of one or more materials and may be formulated to improve strength or other properties of the cover  402 . In some cases, the cover  402  may include a sheet of chemically strengthened material having one or more coatings including an anti-reflective (AR) coating, an oleophobic coating, or other type of coating or optical treatment. In some cases, the cover  402  includes a sheet of material that is less than 1 mm thick. In some cases, the sheet of material is less than 0.80 mm. In some cases, the sheet of material is approximately 0.60 mm or less. The cover  402  may be chemically strengthened using an ion exchange process to form a compressive stress layer along exterior surfaces of the cover  402 . 
     The cover  402  extends over a substantial entirety of the front surface of the device and may be positioned within an opening defined by the housing  410 . As described in more detail below, the edges or sides of the cover  402  may be surrounded by a protective flange or lip of the housing  410  without an interstitial component between the edges of the cover  402  and the respective flanges of the housing  410 . This configuration may allow an impact or force applied to the housing  410  to be transferred to the cover  402  without directly transferring shear stress through the display  403  or frame  404 . 
     As shown in  FIG. 4 , the display  403  is coupled to an internal surface of the cover  402 . In this example, the display stack includes a display  403  (also referred to as a display element) and a touch-sensing layer  405 , which is positioned between the display  403  and the cover  402 . The display  403  may include an edge-to-edge organic light emitting diode (OLED) display that measures 15.4 cm (6.1 inches) corner-to-corner. The perimeter or non-active area of the display  403  may be reduced to allow for very thin device borders around the active area of the display  403 . In some cases, the display  403  allows for border regions of 1.5 mm or less. In some cases, the display  403  allows for border regions of 1 mm or less. In one example implementation, the border region is approximately 0.9 mm. The display  403  may have a relatively high pixel density of approximately 450 pixels per inch (PPI) or greater. In some cases, the display  403  has a pixel density of approximately 460 PPI. 
     As shown in  FIG. 4 , the display stack includes both a display (element)  403  and a separate touch-sensing layer  405 , and includes an array of capacitive electrodes that are configured to sense the presence and location of one or more touches along the external surface of the cover  402 . The electrodes of the touch-sensing layer  405  may be configured to detect a location of a touch, a gesture input, multi-touch input, or other types of touch input along the external surface of the cover  402 . In some cases, the touch-sensing layer  405  is coupled to or has an integrated flex circuit that extends from one or more of the long sides of the touch-sensing layer  405 , which may reduce the border around the display  403 . As with the previous example described above with respect to  FIG. 2 , the display  403  may have an integrated (on-cell) touch-sensing system. For example, an array of electrodes that are integrated into the OLED display may be time and/or frequency multiplexed in order to provide both display and touch-sensing functionality. In some cases, the display  403  includes another type of display element, such as a liquid-crystal display (LCD). 
     The display  403  may include always-on-display (AOD) functionality. For example, the display  403  may be configurable to allow designated regions or subsets of pixels to be displayed when the device  400  is powered on such that graphical content is visible to the user even when the device  400  is in a low-power or sleep mode. This may allow the time, date, battery status, recent notifications, and other graphical content to be displayed in a lower-power or sleep mode. This graphical content may be referred to as persistent or always-on graphical output. While some battery power may be consumed when displaying persistent or always-on graphical output, the power consumption is typically less than during normal or full-power operation of the display  403 . This functionality may be enabled by only operating a subset of the display pixels and/or at a reduced resolution in order to reduce power consumption by the display  403 . 
     As shown in  FIG. 4 , the device  400  may also include a frame  404  that is positioned below the cover  402  and that extends around an outer periphery of the display  403 . A perimeter of the frame  404  may be attached to a lower or inner surface of the cover  402 . A portion of the frame  404  may extend below the display  403  and may attach the cover  402  to the housing  410 . Because the display  403  is attached to a lower or inner surface of the cover  402 , the frame  404  may also be described as attaching both the display  403  and the cover  402  to the housing  410 . The frame  404  may be formed of a polymer material, metal material, or combination of polymer and metal materials. The frame  404  may support elements of the display stack, provide anchor points for flexible circuits, and/or be used to mount other components and device elements. In some cases, the frame  404  includes one or more metal or conductive elements that provide shielding between device components, such as between the display stack (including display components and touch sensor components) and other components like the haptic actuator  422 , the speaker system  424 , and the like. 
     The cover  402 , touch-sensing layer  405 , display  403 , and frame member  404  may be part of a top module  401  of the device  400 . The top module  401  may be assembled as a subassembly, which may then be attached to a housing member. For example, as described herein, the display  403  and touch-sensing layer  405  may be attached to the cover  402  (e.g., via a transparent adhesive), and the frame member  404  may be attached (e.g., via adhesive) to the cover around a periphery of the display  403 . The top module  401  may then be attached to a housing member of the device  400  by mounting and adhering the frame member  404  to a ledge defined by the housing member. 
     As shown in  FIG. 4 , the device  400  also includes one or more cameras, light emitters, and/or sensing elements that are configured to transmit signals, receive signals, or otherwise operate along the front surface of the device. In this example, the device  400  includes a front camera  406  that includes a high-resolution camera sensor. The front camera  406  may have a 12 megapixel resolution sensor with optical elements that provide a fixed focus and an 85° field of view. The front camera  406  may have an aperture number of f/2.2. The device  400  also includes a facial recognition sensor  452  that includes a depth sensor that includes an infrared light projector and an infrared light sensor that are configured to sense an array of depth points or regions along the face of the user. The array of depth points may be characterized as a unique signature or bio-identifier, which may be used to identify the user and unlock the device  400  or authorize functionality on the device  400  like the purchase of software apps or the use of payment functionality provided by the device  400 . 
     The device may also include one or more other sensors or elements that are integrated into a front-facing sensor array  450 . For example, the front-facing sensor array  450  may include a front light illuminator element for providing a flash or illumination for the front camera  406 . The front-facing sensor array  450  may also include an ambient light sensor (ALS) that is used to detect ambient light conditions for setting exposure aspects of the front camera  406 . The front-facing sensor array  450  may also include an antenna array that is configured to transmit and receive wireless communications along the front surface of the device  400 . The antenna array may include elements that are configured to conduct a 5G wireless protocol that may include mm wave and/or 6 GHz communication signals. The antenna array may include multiple elements and may be configured to use or be used with beam-forming and other similar techniques to facilitate 5G wireless communication. 
       FIG. 4  also illustrates one or more cameras, light emitters, and/or sensing elements that are configured to transmit signals, receive signals, or otherwise operate along the rear surface of the device. As depicted in  FIG. 4 , these elements may be integrated in a sensor array  460 . In this example, the sensor array  460  includes a first camera  461  having a 12 megapixel image sensor and a wide angle lens with an aperture number of f/1.6. The first camera  461  also includes a dual photodiode sensor having an APS+ sensor format. The sensor array  460  also includes a second camera  462  having a 12 megapixel image sensor and a super-wide angle lens (120° FOV) with an aperture number of f/2.4. 
     The sensor array  460  also includes a light illuminator that may be used as a flash for photography or as an auxiliary light source (e.g., a flashlight). The sensor array  460  also features an integrated chassis design that minimizes space while providing the precision alignment required for multiple high-resolution cameras. In some cases, the sensor array  460  also includes a microphone, an ambient light sensor, and other sensors that are adapted to sense along the rear surface of the device  400 . 
     The sensor array  460  may also include a depth sensor that is able to estimate a distance to objects positioned behind the device  400 . The depth sensor may include an optical sensor that uses time-of-flight or other optical effect to measure a distance between the device  400  and an external object. The depth sensor may include one or more optical emitters that are adapted to emit one or more beams of light, which may be used to estimate the distance. In some cases, the one or more beams of light are coherent light beams having a substantially uniform wavelength/frequency. A coherent light source may facilitate depth measurements using a time of flight, phase shift, or other optical effect. In some cases, the depth sensor uses a sonic output, radio output, or other type of output that may be used to measure the distance between the device  400  and one or more external objects. 
     As shown in  FIG. 4 , the cameras  461 ,  462  may be aligned with camera covers  466 ,  467  respectively. The covers  466 ,  467  may be formed from a glass or sapphire material and may provide a clear window through which the cameras  461 ,  462  are able to capture a photographic image. In other cases, the covers  466 ,  467  are optical lenses that filter, magnify or otherwise condition light received by the respective camera  461 ,  462 . The other sensing or transmitting elements of the sensor array  460  may transmit and/or receive signals through a region of the rear cover  472  or through a separate cover (e.g.,  469 ) that is coupled to the rear cover  472 . As shown in  FIG. 4 , the covers  466 ,  467  may extend beyond the exterior surface of the cover  472 , and may define a recess along the interior side of the cover  472 , such that the lens or other element of the cameras  461 ,  462  can extend into the respective recesses. In this way, the device  400  may accommodate a larger lens or other elements of the cameras  461 ,  462  than would be possible if the recess were not provided. 
     The device  400  also includes a battery  430 . The battery  430  provides electrical power to the device  400  and its various systems and components. The battery  430  may include a  4 . 45  V lithium ion battery that is encased in a foil or other enclosing element. The battery  430  may include a rolled electrode configuration, sometimes referred to as “jelly roll” or folded electrode configuration. The battery  430  may be recharged via the charging port  432  (e.g., from a power cable plugged into the charging port  432 ), and/or via a wireless charging system  440 . The battery  430  may be coupled to the charging port  432  and/or the wireless charging system  440  via battery control circuitry that controls the power provided to the battery and the power provided by the battery to the device  400 . The battery  430  may include one or more lithium ion battery cells or any other suitable type of rechargeable battery element. 
     The charging system  440  may include a coil that inductively couples to an output or transmitting coil of a wireless charger. The coil may provide current to the device  400  to charge the battery  430  and/or power the device. In this example, the charging system  440  includes a coil assembly  442  that includes multiple wraps of a conductive wire or other conduit that is configured to produce a (charging) current in response to being placed in an inductive charging electromagnetic field produced by a separate wireless charging device or accessory. The coil assembly  442  also includes an array of magnetic elements that are arranged in a circular or radial pattern. The magnetic elements may help to locate the device  400  with respect to a separate wireless charging device or other accessory. In some implementations, the array of magnets also help to radially locate, orient, or “clock” the device  400  with respect to the separate wireless charging device or other accessory. For example, the array of magnets may include multiple magnetic elements having alternating magnetic polarity that are arranged in a radial pattern. The magnetic elements may be arranged to provide a magnetic coupling to the separate charging device in a particular orientation or set of discrete orientations to help locate the device  400  with respect to the separate charging device or other accessory. This functionality may be described as self-aligning or self-locating wireless charging. As shown in  FIG. 4 , the device  400  also includes a magnetic fiducial  444  for helping to locate the separate wireless charging device or accessory. In one example, the magnetic fiducial  444  is adapted to magnetically couple to a cable or power cord of the separate wireless charging device or other accessory. By coupling to the cable or power cord, the rotational alignment of the device  400  and the separate wireless charging device or other accessory may be maintained with respect to an absolute or single position. Also, by magnetically coupling the cable or cord to the rear surface of the device  400 , the charging device or other accessory may be more securely coupled to the device  400 . 
     In some implementations, the charging system  440  includes an antenna or other element that detects the presence of a charging device or other accessory. In some cases, the charging system includes a near-field communications (NFC) antenna that is adapted to receive and/or send wireless communications between the device  400  and the wireless charger or other accessory. In some cases, the device  400  is adapted to perform wireless communications to detect or sense the presence of the wireless charger or other accessory without using a dedicated NFC antenna. The communications may also include information regarding the status of the device, the amount of charge held by the battery  430 , and/or control signals to increase charging, decrease charging, start charging and/or stop charging for a wireless charging operation. 
     The device  400  may also include a speaker system  424 . The speaker system  424  may be positioned in the device  400  so that a respective speaker port  425  is aligned with or otherwise proximate an audio output of the speaker system  424 . Accordingly, sound that is output by the speaker system  424  exits the housing  410  via the respective speaker port  425 . The speaker system  424  may include a speaker positioned in a housing that defines a speaker volume (e.g., an empty space in front of or behind a speaker diaphragm). The speaker volume may be used to tune the audio output from the speaker and optionally mitigate destructive interference of the sound produced by the speaker. The speaker system  424  may include left and right speakers that are aligned with left and right speaker ports  425 , respectively, in order to produce stereo sound. 
     The device  400  may also include a haptic actuator  422 . The haptic actuator  422  may include a movable mass and an actuation system that is configured to move the mass to produce a haptic output. The actuation system may include one or more coils and one or more magnets (e.g., permanent and/or electromagnets) that interact to produce motion. The magnets may be or may include recycled magnetic material. As described herein, the haptic actuator  422  may have a profile or enclosure shape that facilitates physical integration with the battery  430  and other components of the device  400  in order to minimize space and/or maximize the size of the battery. 
     When the coil(s) are energized, the coil(s) may cause the mass to move, which results in a force being imparted on the device  400 . The motion of the mass may be configured to cause a vibration, pulse, tap, or other tactile output detectable via an exterior surface of the device  400 . The haptic actuator  422  may be configured to move the mass linearly, though other movements (e.g., rotational) are also contemplated. Other types of haptic actuators may be used instead of or in addition to the haptic actuator  422 . 
     The device  400  also includes a logic board  420 . The logic board  420  may include a substrate, and processors, memory, and other circuit elements coupled to the substrate. The logic board  420  may include multiple circuit substrates that are stacked and coupled together in order to maximize the area available for electronic components and circuitry in a compact form factor. The logic board  420  may include provisions for a subscriber identity module (SIM). The logic board  420  may include electrical contacts and/or a SIM tray assembly for receiving a physical SIM card and/or the logic board  420  may include provisions for an electronic SIM. The logic board  420  may be wholly or partially encapsulated to reduce the chance of damage due to an ingress of water or other fluid. 
     The logic board  420  may also include a liquid detection circuit  427  that is located proximate to the charging opening  426  or other opening in the housing  410 . The liquid detection circuit  427  may include a resistive or conductive sensor that is configured to electrically detect moisture above a given threshold and transmit a signal to the processor in order to record a liquid exposure event. The liquid detection circuit  427  may also include a visual element that changes color or provides some other visual indicia when exposed to moisture above a certain threshold. In some cases, the liquid detection circuit  427  is positioned within a sealed internal volume of a waterproof or water resistant device and is configured to detect liquid ingress due to a mechanical breach of the housing  410  or physical damage to the device  400 . 
     The logic board  420  may also include wireless communications circuitry, which may be coupled to and/or otherwise use the housing members  411 ,  412 ,  413 ,  414 ,  415 , or  416  (or portions thereof) as radiating members or structures to provide wireless communications. The logic board  420  may also include components such as accelerometers, gyroscopes, near-field communications circuitry and/or antennas, compasses, and the like. In some implementations, the logic board  420  may include a magnetometer that is adapted to detect and/or locate an accessory. For example, the magnetometer may be adapted to detect a magnetic (or non-magnetic) signal produced by an accessory of the device  400  or other device. The output of the magnetometer may include a direction output that may be used to display a directional indicia or other navigational guidance on the display  403  in order to guide the user toward a location of the accessory or other device. 
     The logic board  420  may also include one or more pressure transducers that may be operable to detect changes in external pressure in order to determine changes in altitude or height. The pressure sensors may be externally ported and/or positioned within a water-sealed internal volume of the housing  410 . The output of the pressure sensors may be used to track flights of stairs climbed, a location (e.g., a floor) of a multi-story structure, movement performed during an activity in order to estimate physical effort or calories burned, or other relative movement of the device  400 . 
     The logic board  420  may also include global position system (GPS) electronics that may be used to determine the location of the device  400  with respect to one or more satellites (e.g., a Global Navigation Satellite System (SNSS)) in order to estimate an absolution location of the device  400 . In some implementations, the GPS electronics are operable to utilize dual frequency bands. For example, the GPS electronics may use L1 (L1C), L2 (L2C), L5, L1+L5, and other GPS signal bands in order to estimate the location of the device  400 . 
     As shown in  FIG. 4 , the housing may include a cover  472  (e.g., rear or back cover) that may define a substantial entirety of the rear surface of the device  400 . The cover  472  may be formed from a glass, glass ceramic, ceramic, or other material substrate having portions that are less than 1 mm thick. In some cases, the substrate has portions that are less than 0.80 mm. In some cases, the substrate has portions that are approximately 0.60 mm or less. The cover  472  may have a uniform thickness or, in some cases, may have a thickened or raised portion that surrounds the camera covers  466 ,  467 . The cover  472  may be machined (e.g., ground) into a final shape before being polished and/or textured to provide the desired surface finish. The texture may be specially configured to provide a matte appearance while also being resistant to collecting a buildup of skin, lint, or other debris. A series of cosmetic layers may be formed along the inner surface of the cover  472  to provide a desired optical effect and final color of the device  400 . 
     Similar to as described above with respect to cover  402 , the cover  472  may be positioned at least partially within an opening defined in the housing  410 . Also similar to as described above with respect to cover  402 , the edges or sides of the cover  472  may be surrounded by a protective flange or lip of the housing  410  without an interstitial component between the edges of the cover  472  and the respective flanges of the housing  410 . The cover  472  may be chemically strengthened using an ion exchange process to form a compressive stress layer along exterior surfaces of the cover  472 . 
     As described above, the housing  410  may include housing members  411 ,  412 ,  413 ,  414 ,  415 , and  416  structurally joined together via joint structures  418 .  FIG. 4  illustrates how the joint structures  418  may extend over inner surfaces of the housing members. More particularly, a portion of the joint structures  418  may contact, cover, encapsulate, and/or engage with retention features of the housing members that extend from the inner surfaces of the housing members. 
     Housing members  411 ,  412 ,  413 ,  414 ,  415 , and  416  may also be referred to herein as housing segments and may be formed from aluminum, stainless steel, or other metal or metal alloy material. As described herein, the housing members  411 ,  412 ,  413 ,  414 ,  415 , and  416  may provide a robust and impact resistant sidewall for the device  400 . In the present example, the housing members  411 ,  412 ,  413 ,  414 ,  415 , and  416  define a flat sidewall that extends around the perimeter of the device  400 . The flat sidewall may include rounded or chamfered edges that define the upper and lower edges of the sidewall of the housing  410 . The housing members  411 ,  412 ,  413 ,  414 ,  415 , and  416  may each have a flange portion or lip that extends around and at least partially covers a respective side of the front and rear covers  402 ,  472 . There may be no interstitial material or elements between the flange portion or lip and the respective side surface of the front and rear covers  402 ,  472 . This may allow forces or impacts that are applied to the housing  410  to be transferred to the front and rear covers  402 ,  472  without affecting the display or other internal structural elements, which may improve the drop performance of the device  400 . 
     As shown in  FIG. 4 , the device  400  includes multiple antennas that may be adapted to conduct wireless communication using a 5G communication protocol. In particular, the device  400  may include a (front-fired) antenna array  486  that is positioned near the earpiece of the device  400  and configured to transmit and receive wireless communication signals through the cover  402 . The device  400  may also include a (side-fired) antenna array  482  that is configured to transmit and receive wireless communication signals through an antenna window  483  or waveguide formed along or otherwise integrated with the side wall of the housing  410 . The side-fired antenna array  482  may be coupled to the logic board  420  via a flexible circuit element or other conductive connection, as described herein. The device  400  may also include a (rear-fired) antenna array  484  that may be configured to transmit and receive wireless communication signals through the cover  472 . The antenna array  484  may be attached to a back or bottom surface of the logic board  420 . Each of the antenna arrays  482 ,  484 ,  486  may be adapted to conduct millimeter wave 5G communications and may be adapted to use or be used with beam-forming or other techniques to adapt signal reception depending on the use case. The device  400  may also include multiple antennas for conducting multiple-in multiple-out (MIMO) wireless communications schemes, including 4G, 4G LTE, and/or 5G MIMO communication protocols. As described herein, one or more of the housing members  411 ,  412 ,  413 ,  414 ,  415 , and  416  may be adapted to operate as antennas for a MIMO wireless communication scheme (or other wireless communication scheme). 
       FIG. 5  depicts an exploded view of an example electronic device. In particular,  FIG. 5  depicts an exploded view of a device  500 , showing various components of the device  500  and example arrangements and configurations of the components. The description of the various components and elements of device  100  of  FIGS. 1A and 1B  may also be applicable to the device  500  depicted in  FIG. 5 . A redundant description of some of the components is not repeated herein for clarity. 
     As shown in  FIG. 5 , the device  500  includes a cover  502  (e.g., a front cover), which may be formed of glass, ceramic, or other transparent substrate. In this example, the cover  502  may be formed from a glass or glass-ceramic material. A glass-ceramic material may include both amorphous and crystalline or non-amorphous phases of one or more materials and may be formulated to improve strength or other properties of the cover  502 . In some cases, the cover  502  may include a sheet of chemically strengthened material having one or more coatings including an anti-reflective (AR) coating, an oleophobic coating, or other type of coating or optical treatment. In some cases, the cover  502  includes a sheet of material that is less than 1 mm thick. In some cases, the sheet of material is less than 0.80 mm. In some cases, the sheet of material is approximately 0.60 mm or less. The cover  502  may be chemically strengthened using an ion exchange process to form a compressive stress layer along exterior surfaces of the cover  502 . 
     The cover  502  extends over a substantial entirety of the front surface of the device and may be positioned within an opening defined by the housing  510 . As described in more detail below, the edges or sides of the cover  502  may be surrounded by a protective flange or lip of the housing  510  without an interstitial component between the edges of the cover  502  and the respective flanges of the housing  510 . This configuration may allow an impact or force applied to the housing  510  to be transferred to the cover  502  without directly transferring shear stress through the display  503  or frame  504 . 
     As shown in  FIG. 5 , the display  503  is coupled to an internal surface of the cover  502 . The display  503  may include an edge-to-edge organic light emitting diode (OLED) display that measures  16 . 97  cm ( 6 . 68  inches) corner-to-corner. The perimeter or non-active area of the display  503  may be reduced to allow for very thin device borders around the active area of the display  503 . In some cases, the display  503  allows for border regions of 1.5 mm or less. In some cases, the display  503  allows for border regions of 1 mm or less. In one example implementation, the border region is approximately 0.9 mm. The display  503  may have a relatively high pixel density of approximately 450 pixels per inch (PPI) or greater. In some cases, the display  503  has a pixel density of approximately 458 PPI. The display  503  may have an integrated (on-cell) touch-sensing system. For example, an array of electrodes that are integrated into the OLED display may be time and/or frequency multiplexed in order to provide both display and touch-sensing functionality. The electrodes may be configured to detect a location of a touch, a gesture input, multi-touch input, or other types of touch input along the external surface of the cover  502 . In some cases, the display  503  includes another type of display element, such as a liquid-crystal display (LCD) without an integrated touch-sensing system. That is, the device  500  may include one or more touch- and/or force-sensing layers that are positioned between the display  503  and the cover  502 . 
     The display  503  may include always-on-display (AOD) functionality. For example, the display  503  may be configurable to allow designated regions or subsets of pixels to be displayed when the device  500  is powered on such that graphical content is visible to the user even when the device  500  is in a low-power or sleep mode. This may allow the time, date, battery status, recent notifications, and other graphical content to be displayed in a lower-power or sleep mode. This graphical content may be referred to as persistent or always-on graphical output. While some battery power may be consumed when displaying persistent or always-on graphical output, the power consumption is typically less than during normal or full-power operation of the display  503 . This functionality may be enabled by only operating a subset of the display pixels and/or at a reduced resolution in order to reduce power consumption by the display  503 . 
     As shown in  FIG. 5 , the device  500  may also include a frame  504  that is positioned below the cover  502  and that extends around an outer periphery of the display  503 . A perimeter of the frame  504  may be attached to a lower or inner surface of the cover  502 . A portion of the frame  504  may extend below the display  503  and may attach the cover  502  to the housing  510 . Because the display  503  is attached to a lower or inner surface of the cover  502 , the frame  504  may also be described as attaching both the display  503  and the cover  502  to the housing  510 . The frame  504  may be formed of a polymer material, a metal material, or a combination of polymer and metal materials. The frame  504  may support elements of the display stack, provide anchor points for flexible circuits, and/or be used to mount other components and device elements. In some cases, the frame  504  includes one or more metal or conductive elements that provide shielding between device components, such as between the display stack (including display components and touch sensor components) and other components like the haptic actuator  522 , the speaker system  524 , and the like. 
     The cover  502 , display stack  503 , and frame member  504  may be part of a top module  501  of the device  500 . The top module  501  may be assembled as a subassembly, which may then be attached to a housing member. For example, as described herein, the display  503  may be attached to the cover  502  (e.g., via a transparent adhesive), and the frame member  504  may be attached (e.g., via adhesive) to the cover around a periphery of the display stack  503 . The top module  501  may then be attached to a housing member of the device  500  by mounting and adhering the frame member  504  to a ledge defined by the housing member. 
     As shown in  FIG. 5 , the device  500  also includes one or more cameras, light emitters, and/or sensing elements that are configured to transmit signals, receive signals, or otherwise operate along the front surface of the device. In this example, the device  500  includes a front camera  506  that includes a high-resolution camera sensor. The front camera  506  may have a 12 megapixel resolution sensor with optical elements that provide a fixed focus and an 85° field of view. The front camera  506  may have an aperture number of f/2.2. The device  500  also includes a facial recognition sensor  552  that includes a depth sensor that includes an infrared light projector and infrared light sensor that are configured to sense an array of depth points or regions along the face of the user. The array of depth points may be characterized as a unique signature or bio-identifier, which may be used to identify the user and unlock the device  500  or authorize functionality on the device  500  like the purchase of software apps or the use of payment functionality provided by the device  500 . 
     The device may also include one or more other sensors or elements that are integrated into a front-facing sensor array  550 . For example, the front-facing sensor array  550  may include a front light illuminator element for providing a flash or illumination for the front camera  506 . The front-facing sensor array  550  may also include an ambient light sensor (ALS) that is used to detect ambient light conditions for setting exposure aspects of the front camera  506 . The front-facing sensor array  550  may also include an antenna array that is configured to transmit and receive wireless communications along the front surface of the device  500 . The antenna array may include elements that are configured to conduct a 5G wireless protocol that may include mm wave and/or 6 GHz communication signals. The antenna array may include multiple elements and may be configured to use or be used with beam-forming and other similar techniques to facilitate 5G wireless communication. 
       FIG. 5  also illustrates one or more cameras, light emitters, and/or sensing elements that are configured to transmit signals, receive signals, or otherwise operate along the rear surface of the device. As depicted in  FIG. 5 , these elements may be integrated in a sensor array  560 . In this example, the sensor array  560  includes a first camera  561  having a 12 megapixel image sensor and a wide angle lens with an aperture number of f/1.6. The first camera  561  may also include a sensor-shifting mechanism that allows for image stabilization and/or optical focusing. In some cases, the image sensor is moved with respect to one or more fixed elements of the optical lens assembly. The sensor array  560  also includes a second camera  562  having a 12 megapixel image sensor and a super-wide angle lens (120° FOV) with an aperture number of f/2.2. The sensor array  560  may also include a third camera  563  having a 12 megapixel image sensor and a telephoto optical lens assembly that enables 2.5× optical zoom. The third camera  563  may also have an aperture number of f/2.4. 
     The sensor array  560  also includes a light illuminator that may be used as a flash for photography or as an auxiliary light source (e.g., a flashlight). The sensor array  560  also features an integrated chassis design that minimizes space while providing the precision alignment required for multiple high-resolution cameras. In some cases, the sensor array  560  also includes a microphone, an ambient light sensor, and other sensors that are adapted to sense along the rear surface of the device  500 . 
     The sensor array  560  may also include a depth sensor  565  that is able to estimate a distance to objects positioned behind the device  500 . The depth sensor  565  may include an optical sensor that uses time-of-flight or other optical effect to measure a distance between the device  500  and an external object. The depth sensor  565  may include one or more optical emitters that are adapted to emit one or more beams of light, which may be used to estimate the distance. In some cases, the one or more beams of light are coherent light beams having a substantially uniform wavelength/frequency. A coherent light source may facilitate depth measurements using a time of flight, phase shift, or other optical effect. In some cases, the depth sensor  565  uses a sonic output, radio output, or other type of output that may be used to measure the distance between the device  500  and one or more external objects. The depth sensor  565  may be positioned proximate a window  571  through which the depth sensor  565  may send and/or receive signals (e.g., laser light, infrared light, visible light, etc.). 
     As shown in  FIG. 5 , the cameras  561 ,  562 ,  563  may be aligned with camera covers  566 ,  567 ,  568 , respectively. The covers  566 ,  567 ,  568  may be formed from a glass or sapphire material and may provide a clear window through which the cameras  561 ,  562 ,  563  are able to capture a photographic image. In other cases, the covers  566 ,  567 ,  568  are optical lenses that filter, magnify, or otherwise condition light received by the respective camera  561 ,  562 ,  563 . The other sensing or transmitting elements of the sensor array  560  may transmit and/or receive signals through a region of the rear cover  572  or through a separate cover (e.g.,  569 ) that is coupled to the rear cover  572 . As shown in  FIG. 5 , the covers  566 ,  567 ,  568  may extend beyond the exterior surface of the cover  572 , and may define a recess along the interior side of the cover  572 , such that the lens or other element of the cameras  561 ,  562 ,  563  can extend into the respective recesses. In this way, the device  500  may accommodate a larger lens or other elements of the cameras  561 ,  562 ,  563  than would be possible if the recess were not provided. 
     The device  500  also includes a battery  530 . The battery  530  provides electrical power to the device  500  and its various systems and components. The battery  530  may include a 4.40 V lithium ion battery that is encased in a foil or other enclosing element. The battery  530  may include a rolled electrode configuration, sometimes referred to as “jelly roll” or folded electrode configuration. The battery  530  may be recharged via the charging port  532  (e.g., from a power cable plugged into the charging port  532 ), and/or via a wireless charging system  540 . The battery  530  may be coupled to the charging port  532  and/or the wireless charging system  540  via battery control circuitry that controls the power provided to the battery and the power provided by the battery to the device  500 . The battery  530  may include one or more lithium ion battery cells or any other suitable type of rechargeable battery element. 
     The wireless charging system  540  may include a coil that inductively couples to an output or transmitting coil of a wireless charger. The coil may provide current to the device  500  to charge the battery  530  and/or power the device. In this example, the wireless charging system  540  includes a coil assembly  542  that includes multiple wraps of a conductive wire or other conduit that is configured to produce a (charging) current in response to being placed in an inductive charging electromagnetic field produced by a separate wireless charging device or accessory. The coil assembly  542  also includes an array of magnetic elements that are arranged in a circular or radial pattern. The magnetic elements may help to locate the device  500  with respect to a separate wireless charging device or other accessory. In some implementations, the array of magnets also help to radially locate, orient, or “clock” the device  500  with respect to the separate wireless charging device or other accessory. For example, the array of magnets may include multiple magnetic elements having alternating magnetic polarity that are arranged in a radial pattern. The magnetic elements may be arranged to provide a magnetic coupling to the separate charging device in a particular orientation or set of discrete orientations to help locate the device  500  with respect to the separate charging device or other accessory. This functionality may be described as self-aligning or self-locating wireless charging. As shown in  FIG. 5 , the device  500  also includes a magnetic fiducial  544  for helping to locate the separate wireless charging device or accessory. In one example, the magnetic fiducial  544  is adapted to magnetically couple to a cable or power cord of the separate wireless charging device or other accessory. By coupling to the cable or power cord, the rotational alignment of the device  500  and the separate wireless charging device or other accessory may be maintained with respect to an absolute or single position. Also, by magnetically coupling the cable or cord to the rear surface of the device  500 , the charging device or other accessory may be more securely coupled to the device  500 . 
     In some implementations, the wireless charging system  540  includes an antenna or other element that detects the presence of a charging device or other accessory. In some cases, the charging system includes a near-field communications (NFC) antenna that is adapted to receive and/or send wireless communications between the device  500  and the wireless charger or other accessory. In some cases, the device  500  is adapted to perform wireless communications to detect or sense the presence of the wireless charger or other accessory without using a dedicated NFC antenna. The communications may also include information regarding the status of the device, the amount of charge held by the battery  530 , and/or control signals to increase charging, decrease charging, start charging and/or stop charging for a wireless charging operation. 
     The device  500  may also include a speaker system  524 . The speaker system  524  may be positioned in the device  500  so that a respective speaker port  525  is aligned with or otherwise proximate an audio output of the speaker system  524 . Accordingly, sound that is output by the speaker system  524  exits the housing  510  via the respective speaker port  525 . The speaker system  524  may include a speaker positioned in a housing that defines a speaker volume (e.g., an empty space in front of or behind a speaker diaphragm). The speaker volume may be used to tune the audio output from the speaker and optionally mitigate destructive interference of the sound produced by the speaker. The speaker system  524  may include left and right speakers that are aligned with left and right speaker ports  525 , respectively, in order to produce stereo sound. 
     The device  500  may also include a haptic actuator  522 . The haptic actuator  522  may include a movable mass and an actuation system that is configured to move the mass to produce a haptic output. The actuation system may include one or more coils and one or more magnets (e.g., permanent and/or electromagnets) that interact to produce motion. The magnets may be or may include recycled magnetic material. As described herein, the haptic actuator  522  may have a profile or enclosure shape that facilitates physical integration with the battery  530  and other components of the device  500  in order to minimize space and/or maximize the size of the battery. 
     When the coil(s) are energized, the coil(s) may cause the mass to move, which results in a force being imparted on the device  500 . The motion of the mass may be configured to cause a vibration, pulse, tap, or other tactile output detectable via an exterior surface of the device  500 . The haptic actuator  522  may be configured to move the mass linearly, though other movements (e.g., rotational) are also contemplated. Other types of haptic actuators may be used instead of or in addition to the haptic actuator  522 . 
     The device  500  also includes a logic board  520 . The logic board  520  may include a substrate, and processors, memory, and other circuit elements coupled to the substrate. The logic board  520  may include multiple circuit substrates that are stacked and coupled together in order to maximize the area available for electronic components and circuitry in a compact form factor. The logic board  520  may include provisions for a subscriber identity module (SIM). The logic board  520  may include electrical contacts and/or a SIM tray assembly for receiving a physical SIM card and/or the logic board  520  may include provisions for an electronic SIM. The logic board  520  may be wholly or partially encapsulated to reduce the chance of damage due to an ingress of water or other fluid. 
     The logic board  520  may also include a liquid detection circuit  527  that is located proximate to the charging opening  526  or other opening in the housing  510 . The liquid detection circuit  527  may include a resistive or conductive sensor that is configured to electrically detect moisture above a given threshold and transmit a signal to the processor in order to record a liquid exposure event. The liquid detection circuit  527  may also include a visual element that changes color or provides some other visual indicia when exposed to moisture above a certain threshold. In some cases, the liquid detection circuit  527  is positioned within a sealed internal volume of a waterproof or water resistant device and is configured to detect liquid ingress due to a mechanical breach of the housing  510  or physical damage to the device  500 . 
     The logic board  520  may also include wireless communications circuitry, which may be coupled to and/or otherwise use the housing members  511 ,  512 ,  513 ,  514 ,  515 , or  516  (or portions thereof) as radiating members or structures to provide wireless communications. The logic board  520  may also include components such as accelerometers, gyroscopes, near-field communications circuitry and/or antennas, compasses, and the like. In some implementations, the logic board  520  may include a magnetometer that is adapted to detect and/or locate an accessory. For example, the magnetometer may be adapted to detect a magnetic (or non-magnetic) signal produced by an accessory of the device  500  or other device. The output of the magnetometer may include a direction output that may be used to display a directional indicia or other navigational guidance on the display  503  in order to guide the user toward a location of the accessory or other device. 
     The logic board  520  may also include one or more pressure transducers that may be operable to detect changes in external pressure in order to determine changes in altitude or height. The pressure sensors may be externally ported and/or positioned within a water-sealed internal volume of the housing  510 . The output of the pressure sensors may be used to track flights of stairs climbed, a location (e.g., a floor) of a multi-story structure, movement performed during an activity in order to estimate physical effort or calories burned, or other relative movement of the device  500 . 
     The logic board  520  may also include global position system (GPS) electronics that may be used to determine the location of the device  500  with respect to one or more satellites (e.g., a Global Navigation Satellite System (SNSS)) in order to estimate an absolution location of the device  500 . In some implementations, the GPS electronics are operable to utilize dual frequency bands. For example, the GPS electronics may use L1 (L1C), L2 (L2C), L5, L1+L5, and other GPS signal bands in order to estimate the location of the device  500 . 
     The housing  510  may also include a chassis  519 , which may be attached to the housing  510 . The chassis  519  may be formed of metal, and may act as a structural mounting point for components of the device  500 . The chassis  519  may define an opening that corresponds to size of the coil assembly  542  of the wireless charging system  540 , such that the chassis  519  does not shield the wireless coil assembly  542  or otherwise negatively affect the inductive coupling between the coil of the wireless charging system  540  and an external wireless charger or accessory. 
     As shown in  FIG. 5 , the housing may include a cover  572  (e.g., rear or back cover) that may define a substantial entirety of the rear surface of the device  500 . The cover  572  may be formed from a glass, glass-ceramic, or other material having portions that are less than 1 mm thick. In some cases, the substrate has portions that are less than 0.80 mm. In some cases, the substrate has portions that are approximately 0.60 mm or less. The cover  572  may have a uniform thickness or, in some cases, may have a thickened or raised portion that surrounds the camera covers  566 ,  567 ,  568 . The cover  572  may be machined (e.g., ground) into a final shape before being polished and/or textured to provide the desired surface finish. The texture may be specially configured to provide a matte appearance while also being resistant to collecting a buildup of skin, lint, or other debris. A series of cosmetic layers may be formed along the inner surface of the cover  572  to provide a desired optical effect and final color of the device  500 . 
     Similar to as described above with respect to cover  502 , the cover  572  may be positioned at least partially within an opening defined in the housing  510 . Also similar to as described above with respect to cover  502 , the edges or sides of the cover  572  may be surrounded by a protective flange or lip of the housing  510  without an interstitial component between the edges of the cover  572  and the respective flanges of the housing  510 . The cover  572  may be chemically strengthened using an ion exchange process to form a compressive stress layer along exterior surfaces of the cover  572 . In some cases, the (rear) cover  572  is formed from the same or a similar material as (front) cover  502 . 
     As described above, the housing  510  may include housing members  511 ,  512 ,  513 ,  514 ,  515 , and  516  structurally joined together via joint structures  518 .  FIG. 5  illustrates how the joint structures  518  may extend over inner surfaces of the housing members. More particularly, a portion of the joint structures  518  may contact, cover, encapsulate, and/or engage with retention features of the housing members that extend from the inner surfaces of the housing members. 
     Housing members  511 ,  512 ,  513 ,  514 ,  515 , and  516  may also be referred to herein as housing segments and may be formed from aluminum, stainless steel, or other metal or metal alloy material. As described herein, the housing members  511 ,  512 ,  513 ,  514 ,  515 , and  516  may provide a robust and impact resistant sidewall for the device  500 . In the present example, the housing members  511 ,  512 ,  513 ,  514 ,  515 , and  516  define a flat sidewall that extends around the perimeter of the device  500 . The flat sidewall may include rounded or chamfered edges that define the upper and lower edges of the sidewall of the housing  510 . The housing members  511 ,  512 ,  513 ,  514 ,  515 , and  516  may each have a flange portion or lip that extends around and at least partially covers a respective side of the front and rear covers  502 ,  572 . There may be no interstitial material or elements between the flange portion or lip and the respective side surface of the front and rear covers  502 ,  572 . This may allow forces or impacts that are applied to the housing  510  to be transferred to the front and rear covers  502 ,  572  without affecting the display or other internal structural elements, which may improve the drop performance of the device  500 . 
     As shown in  FIG. 5 , the device  500  includes multiple antennas that may be adapted to conduct wireless communication using a 5G communication protocol. In particular, the device  500  may include a (front-fired) antenna array  586  that is positioned near the earpiece of the device  500  and configured to transmit and receive wireless communication signals through the cover  502 . The device  500  may also include a (side-fired) antenna array  582  that is configured to transmit and receive wireless communication signals through an antenna window or waveguide formed along or otherwise integrated with the side wall of the housing  510 . The side-fired antenna array  582  may be coupled to the logic board  520  via a flexible circuit element or other conductive connection, as described herein. The device  500  may also include a (rear-fired) antenna array  584  that may be configured to transmit and receive wireless communication signals through the cover  572 . The antenna array  584  may be attached to a back or bottom surface of the logic board  520 . Each of the antenna arrays  582 ,  584 ,  586  may be adapted to conduct millimeter wave 5G communications and may be adapted to use or be used with beam-forming or other techniques to adapt signal reception depending on the use case. The device  500  may also include multiple antennas for conducting multiple-in multiple-out (MIMO) wireless communications schemes, including 4G, 4G LTE, and/or 5G MIMO communication protocols. As described herein, one or more of the housing members  511 ,  512 ,  513 ,  514 ,  515 , and  516  may be adapted to operate as antennas for a MIMO wireless communication scheme (or other wireless communication scheme). 
       FIG. 6A  depicts a partial cross-sectional view of an example electronic device  600 , viewed along line  6 A- 6 A in  FIG. 1A . The electronic device  600  may correspond to or be an embodiment of the electronic devices  100 ,  200 ,  300 ,  400 ,  500 , or any other device described herein. 
     The device  600  may include a housing member  602 , which may correspond to or be an embodiment of the housing member  130 . The housing member  602  may also represent other housing members of the devices described herein, such as the housing members  124 ,  125 ,  126 ,  127 , and  128 . The housing member  602  may define an exterior side surface  603  of the device  600 . The device  600  may also include a cover  604 , which may correspond to or be an embodiment of the cover  102  of  FIGS. 1A-1B  (or any other cover described herein). The cover  604  may define a front exterior surface  606  of the device  600 , which may be planar. In some cases, the cover  604  defines a chamfer  605  that extends around the periphery of the planar front exterior surface  606  and extends between an edge of the front exterior surface  606  and an edge of a side surface  607  of the cover  604 . The device  600  may also include a rear cover  609 , which may correspond to or be an embodiment of the rear cover  132  (or any other rear cover described herein). 
     The cover  604  may be positioned over a display stack  608 , which may correspond to or be an embodiment of the display  103  of  FIGS. 1A-1B  (or any other display described herein). The display stack  608  may be coupled to the cover  604  along an interior surface of the cover  604  via an adhesive  610 , which may be a transparent adhesive. The adhesive  610  may have a thickness, such as about 200 microns, about 300 microns, about 400 microns, or the like. 
     The display stack  608  may include a display element  612 , which may be configured to produce graphical outputs. The display element  612  may be an OLED display, and may include multiple layers and/or other components that facilitate the production of graphical outputs, including, for example, substrates, an anode, a cathode, one or more organic layers, an emissive layer, adhesives, and the like. In some cases, the display element  612  may include an integrated (on-cell) touch-sensing system, as described above. For example, an array of electrodes that are integrated into the OLED display may be time and/or frequency multiplexed in order to provide both display and touch-sensing functionality. In other cases, separate touch- and/or force-sensing systems may be included above or below the display element  612  (each of which may include, for example, capacitive electrode layers, compliant layers, and the like). While an OLED display is described, the display element may be any suitable type of display, such as an LCD display, an active layer organic light emitting diode (AMOLED) display, an organic electroluminescent (EL) display, an electrophoretic ink display, or the like. 
     The display stack  608  may include various electrically active layers and components that need to be electrically interconnected to other electrical components, processors, circuit elements, and the like. Because such layers (e.g., anode and cathode layers of an OLED display) may be sandwiched between other layers of the display stack  608 , a flexible circuit element  622  (e.g., a flexible circuit board) may wrap around a side of the display stack  608  (forming a loop) to electrically couple the electrically active layers of the display stack  608  to a more accessible circuit element  620  of the display stack  608 . More particularly, the flexible circuit element  622  may include conductive traces that interconnect electrical components within the display element  612  (e.g., cathode and anode layers, electrode layers of touch and/or force sensors, on-cell touch-sensing layers, etc.) to other electrical traces, connectors, processors, or other electrical components that are mounted on the circuit element  620 . The circuit element  620  may be a rigid or flexible circuit board. In some cases, a potting material (e.g., an epoxy, foam, or other material or component) may be provided in the loop area  616  between the side of the display stack  608  and the flexible circuit element  622  to help provide structure to the flexible circuit element  622  and to help prevent deformation of the flexible circuit element  622  due to impacts or other damage. Additional details about the potting material are shown and described with respect to  FIGS. 13C-13D . 
     The display stack  608  may include other components in addition to the display element  612  and touch- and/or force-sensing components, such as support and shielding layers, and adhesive layers to hold the various components of the display stack  608  together. For example, the display stack  608  may include a first metal plate  614  that supports the display element  612  and imparts structural support, rigidity, and flatness to the display element  612 . The first metal plate  614  may have the same or substantially the same front-facing area as the display element  612  (e.g., the first metal plate  614  may have a front-facing area that is greater than 90% of the display element  612 ). The display stack may also include a second metal plate  618  that supports the circuit element  620 . The second metal plate  618  may have a smaller frontal area than the first metal plate  614 , and may have a size that is similar to the circuit element  620 . Both the circuit element  620  and the second metal plate  618  may have a front-facing area that is less than 50% of the front-facing area of the display element  612 , and optionally less than 30% of the front-facing area of the display element  612 . 
     The display stack  608  may include other layers and components, as well. For example, the display stack  608  may include adhesives between various layers and elements in the display stack  608 . More specifically, the display stack  608  may include an adhesive between the display element  612  and the first metal plate  614 , an adhesive between the first metal plate  614  and the second metal plate  618 , and an adhesive between the second metal plate  618  and the circuit element  620 . Of course, other layers, sheets, substrates, adhesives, and/or other components may also be included in the display stack  608 . 
     The cover  604  may be attached to a frame member  624 . The frame member  624  may be formed from or include a polymer material, and may extend around all or substantially all of a perimeter of the cover  604 . The frame member  624  may at least partially encapsulate and/or otherwise be coupled to a back plate  628 . The back plate  628  may be formed of or include metal, plastic, or any other suitable material. The back plate  628  may provide shielding and structural support to the device, and may protect the display stack  608  by forming an at least partially enclosed area in which the display stack  608  is positioned. The back plate  628  may be at least partially encapsulated in the frame member  624 , or it may be attached to the frame member  624  in any other suitable manner. 
     The frame member  624  may be attached to the housing member  602 . For example, the frame member  624  may be attached to a ledge  623  or other feature defined by the housing member, as depicted in  FIG. 6A . The ledge  623  may extend from an interior side of the housing member  602 . The ledge  623  may be part of a monolithic structure of the housing member  602  (e.g., the housing member may be molded, machined, or otherwise formed from a single piece of material to define the ledge  623  as well as the other features and/or surfaces of the housing member  602 ). The frame member  624  may be attached to the housing member  602  via an adhesive  625 , which may be between and in contact with the ledge  623  and the frame member  624 . The adhesive  625  may be any suitable adhesive, such as a pressure sensitive adhesive (PSA), heat sensitive adhesive (HSA), adhesive film, epoxy, or the like. In some cases, the ledge or other feature to which the frame member  624  is attached acts as a datum surface for the frame member  624 . Thus, the alignment (e.g., flushness) of the front exterior surface  606  of the cover  604  and the upper portion  632  of the housing member  602  may be defined or established by the location of the ledge (relative to the upper portion  632 ), as well as the location of the bottom surface of the frame member  624  (relative to the front exterior surface  606  of the cover  604 ). 
     The cover  604  may be attached to the frame member  624  via an adhesive  626 . The frame member  624  may define a recessed region  627  (which defines a bonding surface), and the adhesive  626  may be placed in the recessed region  627 . The recessed region  627  may provide a trough-like volume for the adhesive  626 , while also allowing a flange portion  629  of the frame member  624  to contact the underside of the cover  604 . The direct contact between the flange portion  629  of the frame member  624  and the cover  604  may provide a rigid connection between the cover  604  and the frame member  624  and may ensure that forces applied to the cover  604  are transferred to the structural frame member  624 . While the recessed region  627  is defined by a single flange portion  629  (e.g., on the right side of the recessed region  627 ), other configurations are also possible, such as a recessed region defined by two flange portions or other sidewall-like features (e.g., a channel defined by two walls). 
     The housing member  602  may be specifically configured to allow a close coupling between it and the assembly that includes the cover  604 , the display stack  608 , and the frame member  624 . In particular, the housing member  602  may define a recessed region  630  (also referred to simply as a recess) along an interior surface of the housing member  602  that is adjacent or proximate the frame member  624 . The recessed region  630  may be formed into the housing member  602  in any suitable way. For example, the recessed region  630  may be machined into the housing member  602 , or the housing member  602  may be molded or cast and the recessed region  630  may be formed as part of the casting or molding process. 
     The recessed region  630  may correspond to a portion of the housing member  602  that is thinner than other portions of the housing member  602 . For example, the housing member  602  may define an upper portion  632  and a lower portion  634  that have a greater thickness (in the left-to-right direction as depicted in  FIG. 6A ) than the portion of the housing member  602  that defines the recessed region  630 . 
     The recessed region  630  may be configured so that the interior surface of the housing member  602  that is directly opposite the frame member  624  is set apart from the frame member  624  by a target distance. The target distance may be selected so that deformations or deflections of the housing member  602  along the side wall (e.g., due to the device  600  being dropped or otherwise subjected to predictable misuse or damage) do not contact the frame member  624  and/or the display stack  608 . More particularly, the recessed region  630  allows the device  600  to accommodate a certain amount of deformation of the side wall of the housing member  602  without the housing member  602  contacting the frame member  624 . For example, the inner surface of the recessed region  630  may be spaced apart from the outer peripheral surface  631  of the frame member  624  by about 0.3 mm, 0.5 mm, 0.7 mm, 1.0 mm, or any other suitable distance. In some cases, the distance between the inner surface of the recessed region  630  and the outer surface of the frame member  624  is greater than a housing deformation that is produced as a result of a standard test, such as a side impact test (e.g., in which the device  600  is dropped from a certain height (e.g., 1 m, 2 m, or 3 m) onto a certain surface (e.g., an edge of a triangular prism). 
     In some cases, the height (e.g., the vertical direction as depicted in  FIG. 6A ) of the recessed region  630  (and optionally the height of the recessed region  630  and the additional recessed region  636  combined) is equal to or greater than a height of the frame member  624 . In this way, the recessed region  630  (optionally with the additional recessed region  636 ) is large enough so that the frame member  624  could extend at least partially into the recessed region  630  in the event of an impact or drop (e.g., causing the housing member  602  to deform or deflect), without the frame member  624  contacting the housing member  602 . This may help prevent damage to the frame-cover interface and help prevent separation of the cover  604  from the frame member  624  (e.g., by preventing or reducing the magnitude of forces applied to the frame member  624  by the housing member  602  in the event of an impact, drop, or the like). In some cases, the height of the recessed region  630  (and optionally the recessed region  630  combined with the additional recessed region  636 ) extends from the ledge  623  to a height or location that is at or above the bottom surface of the cover  604 . 
     In some cases, the distance between the inner surface of the recessed region  630  and the outer surface of the frame member  624  is greater than a distance between a side surface  607  of the cover  604  and an inner side surface  633 . Thus, for example, a deformation or deflection of the housing member  602  towards the cover  604  and the frame member  624  may result in the side surface  607  of the cover  604  contacting the inner side surface  633  of the frame member  624  before the housing member  602  (and in particular the inner surface of the recessed region  630 ) contacts the frame member  624 . Thus, by forming a recessed region  630  that establishes a greater distance between the housing member  602  and the frame member  624  than the distance between the housing member  602  and the cover  604 , the risk of contact between the housing member  602  and the frame member  624  during deformation or deflection of the housing member  602  may be reduced. 
     The side surface  607  of the cover  604  may abut an inner side surface  633  of the housing member  602  (or be adjacent the inner side surface  633  without interstitial components, as described herein). In some cases, there is no interstitial component or other material between the side surface  607  of the cover  604  and the inner side surface  633  of the housing member  602 . This construction provides several structural and cosmetic advantages. For example, the lack of a bezel or other interstitial component or material between these surfaces provides a clean, frameless appearance to the front of the device  600 . In particular, the front-facing surfaces of the device  600  may be defined only by the upper portion  632  of the housing member  602  and the front exterior surface  606  of the cover  604 . While the side surface  607  of the cover  604  may abut an inner side surface  633  of the housing member  602 , in some cases an air gap may exist between these surfaces. In some cases, an adhesive or sealing material may be positioned between the side surface  607  of the cover  604  and the inner side surface  633  of the housing member  602 . In such cases, the adhesive or sealing material may be the only material between these surfaces, may be in contact with both surfaces, and may have a thickness less than about 0.5 mm, 0.3 mm, 0.1 mm, 0.05 mm, or any other suitable thickness. 
     The proximity between the side surface  607  of the cover  604  and the inner side surface  633  of the housing member  602  may define a load path through the upper portion  632  of the housing member  602  and into the cover  604 . For example, forces applied to the exterior side surface  603  of the housing member  602  may be directed into the cover  604  at the interface between the side surface  607  of the cover  604  and the inner side surface  633  of the housing member  602 . (In cases where the inner side surface  633  abuts the side surface  607  of the cover  604 , loads may be directly transferred or directed into the cover  604 , while in cases where there is an air gap between the inner side surface  633  and the side surface  607  of the cover  604 , the forces may initially cause the gap to close such that the inner side surface  633  comes into contact with the side surface  607 .) The rigidity and structural integrity of the cover  604  may help prevent or reduce deformation of the housing member  602  in the event of a drop or other impact on the exterior side surface  603 , thereby protecting internal components of the device  600  from damage due to the housing member  602  contacting them. By defining the load path through the cover  604  and by configuring the housing member  602  to include the recessed region  630 , the device  600  may be designed to omit the frame member  624  from the load path during many impact events (e.g., the device  600  being dropped). For example, as shown in  FIG. 6A , the recessed region  630  ensures that the frame member  624  is set apart from the housing member  602  by a suitable distance. Also, no portion of the frame member  624  is between the housing member  602  and the cover  604 . Accordingly, the frame member  624  may be positioned so that it is not contacted or impacted by the housing member  602 , even if the housing member  602  is subjected to an impact, deformed, deflected, or otherwise damaged (up to a certain amount of deformation or deflection). 
     In some cases, the rear cover  609  interfaces with the lower portion  634  of the housing member  602 , in that the lower portion  634  may contact a side surface of the rear cover  609 , thereby defining a load path through the lower portion  634  and into the rear cover  609 . 
     In some cases, the housing member  602  may include an additional recessed region  636 . The additional recessed region  636  may be configured so that the housing member  602  in that region is set a distance away from components in the display stack  608 , touch- and/or force-sensing components, antennas, or other electrical components of the device  600 . In particular, as the housing member  602  may be formed of metal, the metal may capacitively couple to other electronic components. By increasing the distance between the metal of the housing member  602  and the electrical components, the capacitive coupling may be reduced to an acceptable level. Accordingly, the additional recessed region  636  may be configured so that the distance between the additional recessed region  636  and another electrical component is greater than about 0.5 mm, 1.0 mm, 1.5 mm, 2.0 mm, or any other suitable distance. In some cases, the recessed region  630  may be recessed further (and thus correspond to a thinner portion of the housing member  602 ) than the additional recessed region  636 . 
     The frame member  624  may also define a recess  657 . The recess  657  may be defined at least partially by the flange portion  629 , and may be configured to accommodate or receive at least part of the display stack  608 . For example, a loop  635  defined by the flexible circuit element  622  may extend at least partially into the recess  657 , as shown in  FIG. 6A  (as well as  6 B- 6 E). In some cases, in order to facilitate the attachment of the cover  604  to the frame member  624 , the frame member  624  may be deflected so that the loop  635  can clear the frame member  624  without contacting the flange portion  629 . For example, the cover  604  and the display stack  608  may be attached together, and then the cover and display stack may be lowered onto the frame member  624 . Without deflecting the frame member  624 , the loop  635  may contact the flange portion  629  or another portion of the frame member  624 . By deflecting the frame member  624  (e.g., pulling the frame member  624  to the left, relative to the orientation shown in  FIG. 6A , with a fixture or tool), the loop  635  may be positioned in the recess (and at least partially overlapping the flange portion  629 ) without the loop  635  contacting the frame member  624 . By positioning the loop  635  at least partially in the recess  657 , greater packing efficiency may be achieved, as the frame member can be positioned closer to the active area of the display, thus reducing display borders and other unused space in the device. 
     As noted above with respect to  FIG. 6A , a display stack  608  may be attached to a cover  604  via an adhesive  610 , which may be a transparent adhesive to allow the graphical outputs that are produced by the display stack  608  to be visible through the cover  604 . In order to increase the amount of internal space in a device, it may be advantageous to use a thin adhesive to attach the display stack  608  to the cover  604 . However, the structure of the frame member  624  and the display stack  608  (and/or other device components) may limit the minimum thickness of the adhesive  610 . For example, if the thickness of the adhesive  610  in  FIG. 6A  is reduced, the flexible circuit element  622  may contact or be too close to the flange portion  629  of the frame member  624 . 
       FIG. 6B  illustrates another example configuration of a frame member and cover that may enable the use of a thinner adhesive to attach a display stack to a cover. For example,  FIG. 6B  illustrates a cover  640  with a thinned outer region  650 . Except for the thinned outer region  650 , the cover  640  may be the same as or similar to the cover  604 , and for brevity those details are not repeated here. The cover  640  may be attached to a frame member  656  via an adhesive  652  that is positioned in a recessed region  654  (which defines a bonding surface) of the frame member  656 . The frame member  656 , adhesive  652 , and recessed region  654  may be the same as or similar to the frame member  624 , adhesive  626 , and recessed region  627 , and for brevity those details are not repeated here. 
     The thinned outer region  650  may extend along one or more edges of the cover  640 . For example, the thinned outer region  650  may extend along one edge of the cover  640 , and in particular, an edge of the cover  640  that is proximate a flexible circuit element  643  of the display stack  642 . In some cases, the thinned outer region  650  may extend along two, three, or four sides of the cover  640 . For example, in the case of a substantially rectangular cover, the thinned outer region  650  may extend around the entire outer periphery of the cover  640  (e.g., the thinned outer region  650  may extend around a display region of the cover  640 , where the display region corresponds to a central region of the cover  640  through which the display is visible and/or produces graphical outputs). The display stack  642  and the flexible circuit element  643  may be the same as or similar to the display stack  608  and the flexible circuit element  622 , and for brevity those details are not repeated here. 
     The thinned outer region  650  may facilitate the use of a thinner layer of adhesive  644  (e.g., optically clear or transparent adhesive) to attach the display stack  642  to the cover  640 . More particularly, the thinned outer region  650  may allow a flange portion  648  (similar to the flange portion  629 ,  FIG. 6A ) to be positioned further towards the exterior surface of the cover  640  (e.g., higher in a vertical direction, as depicted in  FIG. 6B ), the display stack  642 , and thus the flexible circuit element  643 , may likewise be positioned further towards the exterior surface of the cover  640  without causing the flexible circuit element  643  to contact or otherwise interfere with the flange portion  648 . Accordingly, the thickness of the adhesive  644  may be made thinner (e.g., relative to the adhesive  610 ), resulting in an overall height  658  of the display stack  642  and cover  640  that is less than a height of a device that does not include a cover with a thinned outer region (e.g., the overall height  658  may be less than the overall height  659  in  FIG. 6A ). In some cases, the adhesive  644  has a thickness of about 150 microns, about 125 microns, about 100 microns, or about 75 microns. 
     The thinned outer region  650  of the cover  640  may have a thickness  641  of about 400 microns, and the main portion  647  of the cover  640  (e.g., the portion to which the display stack  642  is attached and that includes the graphically active area of the device) may have a thickness  649  of about 600 microns. In some cases, the thinned outer region  650  is about 100 microns, about 200 microns, or about 300 microns thinner than the main portion  647  of the cover  640 . The thickness  641  may be between about 375 microns to about 425 microns, and the thickness  649  may be between about 575 microns to about 625 microns. 
     The cover  640  may define a transition region  646  that extends from the thinned outer region  650  to the main portion  647  of the cover  640 . The transition region  646  may define a curved portion of the bottom surface of the cover  640  that extends from the thinned outer region  650  to the main portion  647  of the cover  640 . The transition surface may have a continuous curve (as shown), or it may have another shape or configuration. For example, the transition surface may be fully or partially planar, and may resemble a chamfered surface. 
     The cover  640  may be formed in various ways. For example, the cover  640 , including its thinned outer region  650 , may be formed by molding (e.g., heating glass or another transparent material and applying a mold or press to produce the desired shape), machining (e.g., grinding, lapping, or otherwise removing material from a sheet to form the desired shape), and/or by additive manufacturing (e.g., adhering, bonding, or otherwise attaching a first glass sheet to a second glass sheet to form the desired shape). Combinations of these processes may also be used to form the cover  640  and produce the thinned outer region  650 . 
     Covers of the electronic devices described herein may be attached to frame members via an adhesive. As described with respect to  FIG. 6A , and shown in  FIGS. 6A and 6B , a frame member may define a recessed region (e.g., the recessed regions  627 ,  654 ), and an adhesive may be placed in the recessed region. The recessed region may provide a trough-like volume for the adhesive, while also allowing a flange portion of the frame member to contact the underside of the cover. 
       FIG. 6C  illustrates an example cover and frame member configuration in which a flange portion of the frame member does not contact the cover. In particular,  FIG. 6C  illustrates a cover  660  (which may be the same as or similar to the cover  604 ) and a frame member  661 . The frame member  661  defines a recessed region  664  (which defines a bonding surface) defined by a flange portion  662 . An adhesive  663  is positioned in the recessed region  664  and bonds the cover  660  to the frame member  661 . In this configuration, the interior surface of the cover  660  does not contact a surface  665  of the flange portion  662 . Rather, a portion of the adhesive  663  is positioned between the surface  665  and the interior surface of the cover  660  (e.g., in a gap or space  666  between the surfaces). By positioning some of the adhesive  663  between the surfaces, the adhesive  663  may provide a compliance or flexibility in the coupling between the cover  660  and the frame member  661 , which may provide additional resilience and/or resistance to breaking or other damage in the event of a drop or other impact event. Further, positioning some of the adhesive  663  between the surfaces may allow a greater degree of control over the positioning of the cover  660  relative to the frame member  661 . For example, differences in the thickness of the cover  660  or the size or shape of the frame member  661  (e.g., due to manufacturing tolerance) may be accommodated by changing the distance between the interior surface of the cover  660  and the surface  665  of the frame member  661 . In some cases, the adhesive  663  may be deposited on the cover  660  and/or in the recessed region  664  in a flowable state, and the cover  660  and the frame member  661  are attached together using a fixture that establishes the target relative positions of the cover  660  and frame member  661 . Accordingly, the adhesive  663  may flow to fill and accommodate whatever gap results when the cover  660  and frame member  661  are positioned as intended. 
       FIG. 6D  illustrates an example cover and frame member configuration in which a frame member defines two flange portions that contact the cover and define two sides or walls of a trough for receiving and containing an adhesive. In particular,  FIG. 6D  illustrates a cover  670  (which may be the same as or similar to the cover  604 ) and a frame member  671 . The frame member  671  defines a recessed region  675  (which defines a bonding surface) defined by a first flange portion  673  and a second flange portion  674 . The first and second flange portions  673 ,  674  define a trough or channel that retains an adhesive  672 . By using two flange portions as shown in  FIG. 6D , the adhesive may be prevented or inhibited from spilling or flowing out of the recessed region, and may provide an improved bond between the adhesive  672  and the cover  670  and frame member  671 . In some cases, the use of two flange portions may allow the use of a less viscous adhesive due to the additional containment/retention ability of the trough. Further, using two flange portions may increase the surface area of the contact between the cover  670  and the frame member  671 , which may reduce stress concentrations between the frame member  671  and the cover  670  and/or provide other structural advantages. 
       FIG. 6E  illustrates an example cover and frame member configuration in which a ramp structure is used along the bottom surface of the front cover to deflect a portion of the display stack downwards (e.g., away from the front cover) to help prevent or reduce the risk of contact between the display stack and the frame member. For example,  FIG. 6E  illustrates a front cover  681  (which may be the same as or similar to the cover  604 ), to which a frame member  682  may be attached (as described above). A display stack  687  may be attached to the cover  604  via a transparent adhesive  686 . 
     A ramp structure  683  may be positioned between the bottom surface of the front cover  681  and the display stack  687 , and more particularly, between the front cover  681  and a loop  684  of the display stack (which may be defined at least in part by a flexible circuit element of the display stack  687 ). The ramp structure  683  is configured to deflect the loop  684  away from the front cover  681  (e.g., downward as shown in  FIG. 6E ). The ramp structure  683  may have a curved or flat ramp surface (e.g., the surface that contacts the loop  684 ) and may have a maximum thickness of between about 100 microns and about 200 microns. The maximum thickness of the ramp structure  683  may equate to a reduction in thickness of the adhesive  686  that adheres the display stack  687  to the front cover  681 . For example, if the adhesive  686  is reduced by about 150 microns (and the dimensions of the frame member and front cover remain the same), a ramp structure having a maximum thickness of about 150 microns (e.g., the same amount that the adhesive thickness was reduced) may be used to deflect the loop in order to maintain the same or similar distance between the loop and the frame member (e.g., the same distance that was present with the thicker adhesive and no ramp structure). Accordingly, the ramp structure  683  may facilitate the use of thinner adhesives, resulting in thinner devices and/or more space inside devices for other components (e.g., larger batteries). 
     A ramp structure, such as the ramp structure  683 , may be formed of various materials and have various configurations.  FIGS. 6F-6I  illustrate various example ramp structures.  FIG. 6F  illustrates the front cover  681 . The front cover  681  may have a mask layer  679  applied to the bottom surface, a chamfered edge of the front cover  681 , and at least a portion of a side surface of the front cover  681 . In  FIG. 6F , the ramp structure is defined by a thickened region of the adhesive  688 , which is the same adhesive that attaches the display stack to the front cover  681 . The adhesive  688  may be a multi-layer adhesive structure such as a transparent polymer (with a thicker region defining the ramp structure) with adhesive on the top and bottom surfaces. In some cases, the adhesive  688  may be a monolithic structure, such as an epoxy, liquid, or gel that is formed or molded to include the ramp structure as shown in  FIG. 6F . An additional adhesive layer may be used to attach the monolithic structure to the front cover and/or attach the display stack to the monolithic structure. 
       FIG. 6G  illustrates another example ramp structure  690 . In this example, the ramp structure  690  may be formed by a stack of layers. The layers that define the ramp structure  690  may be formed from any suitable material, such as a plurality of ink layers, adhesive film layers, dye layers, or other masking material layers (e.g., the same material as the mask layer  679 ). In some cases, the ramp structure  690  is formed as part of the masking process, where the mask layer  679  is applied, and then additional layers of the masking material are added to form the ramp structure  690 . In some cases, the multi-layer mask structure is fabricated separately, and then applied (e.g., with an adhesive) to the mask layer  679 . The adhesive  689  (e.g., a transparent adhesive, which may be the same as or similar to the adhesive  686 ) may be applied to the front cover  681  and the ramp structure  690 , as shown in  FIG. 6G . 
       FIG. 6H  illustrates another example ramp structure  691 . In this example, the ramp structure  691  may be formed by a folded structure. The folded structure that defines the ramp structure  691  may be formed from any suitable material, such as adhesive films, layers of ink, dye, or other masking material (e.g., the same material as the mask layer  679 ). In some cases, the ramp structure  691  is formed as part of the masking process, where the mask layer  679  is applied, and then additional layers of the masking material are added to form the ramp structure  691 . In some cases, the multi-layer mask structure is fabricated separately, and then applied (e.g., with an adhesive) to the mask layer  679 . The adhesive  689  (e.g., a transparent adhesive, which may be the same as or similar to the adhesive  686 ) may be applied to the front cover  681  and the ramp structure  691 , as shown in  FIG. 6H . 
       FIG. 6I  illustrates another example ramp structure  692 . In this example, the ramp structure  692  may be formed by a monolithic ramp component that is attached to the front cover  681  (e.g., below the mask layer  679 ). The ramp component may be formed from any suitable material, such as a polymer, foam, or the like. An adhesive (e.g., an adhesive film, a liquid or gel adhesive, or the like) may attach the ramp structure  692  to the front cover  681  (e.g., to the mask layer  679 ). The adhesive  689  (e.g., a transparent adhesive, which may be the same as or similar to the adhesive  686 ) may be applied to the front cover  681  and the ramp structure  692 , as shown in  FIG. 6I . In some cases, the adhesive  686  does not extend over the ramp structure  692 . In such cases, a different adhesive layer may be applied to the ramp structure  692  to secure the loop of the display stack to the front cover  681 . In other cases, an anti-stick coating may be applied to the surface of the ramp structure  692  that contacts the display stack. For example, a polyimide, polyethylene terephthalate, polytetrafluoroethylene, or other suitable polymer material may be adhered to the surface of the ramp structure  692  that contacts and deflects the display stack. 
     As noted above, devices as described herein may include one or more groups of antennas that include elements that are configured to communicate via a 5G wireless protocol (including millimeter wave and/or 6 GHz communication signals).  FIG. 7  depicts a portion of an electronic device  700 , with components removed to better illustrate example antenna groups for 5G wireless communications. 5G communications may be achieved using various different communications protocols. For example, 5G communications may use a communications protocol that uses a frequency band below 6 GHz (also referred to as the sub-6 GHz spectrum). As another example, 5G communications may use a communications protocol that uses a frequency band above 24 GHz (also referred to as the millimeter-wave spectrum). Further, the particular frequency band of any given 5G implementation may differ from others. For example, different wireless communications providers may use different frequency bands in the millimeter-wave spectrum (e.g., one provider may implement a 5G communications network using frequencies around 28 GHz, while another may use frequencies around 39 GHz). The particular antenna group(s) implemented in a device as described herein may be configured to allow communications via one or multiple of the frequency bands that implement 5G communications. 
     The device  700  in  FIG. 7  includes at least two groups of antennas, each configured to operate to provide 5G communications using a different communications protocol. For example, the first antenna group includes multiple antennas to communicate via the sub-6 GHz spectrum, and the second antenna group includes multiple antennas to communicate via the millimeter-wave spectrum. 
     As noted above, the housing members of a device, such as a mobile phone, may be adapted for use as antennas. In the device  700 , for example, the housing  750  may include housing members  701 ,  703 ,  705 ,  707 ,  709 , and  711 . These housing members may be formed from metal or another conductive material, and may be electrically coupled to communications circuitry (as described in greater detail herein) in order to cause portions of the housing members to send and/or receive wireless communications. The housing members  701 ,  703 ,  705 ,  707 ,  709 , and  711  may be coupled together with joining elements  716 ,  718 ,  720 ,  722 ,  724 , and  726  to form the housing members into a single structural housing component. For simplicity, the joining elements  716 ,  718 ,  720 ,  722 ,  724 , and  726  are shown as being separate components, though some of the joining elements may be contiguous (e.g., the joining elements  716  and  718  may be parts of a contiguous molded polymer structure). 
     The joining elements may both mechanically and/or structurally couple the housing members together, and provide electrical isolation between adjacent housing members to facilitate the use of the housing members as radiating antennas. More particularly, with respect to the mechanical coupling, a joining element may securely attach to adjacent housing members (e.g., via mechanical interlocks between the joining element and the housing members and/or via adhesive or chemical bonds between the joining element and the housing members). With respect to the electrical isolation functions, a joining element may provide a requisite electrical isolation between an antenna and another conductive component (e.g., another conductive housing member, whether acting as an antenna or a non-radiating structural member) to reduce attenuation of the antenna performance (e.g., due to capacitive coupling between the antenna and the other conductive component). The joining elements may be formed form or include a nonconductive and/or dielectric material, such as a polymer, fiber-reinforced nylon, epoxy, or the like. Thus, the joining elements may be referred to herein as nonconductive joining elements. 
     The joining elements may be formed by a molding process. For example, the housing members may be placed into a mold or otherwise maintained in a fixed position relative to one another such that gaps are defined between adjacent housing members. One or more polymer materials may then be injected into the gaps (and optionally into engagement with retention structures and/or interlock features defined in the housing members), such that the polymer materials at least partially fill the gaps, and allowed to cure or otherwise harden to form the joining elements. In some cases, joining elements may be formed from multiple different materials. For example, an inner portion of the joining element may be formed of a first material (e.g., a polymer material), and an outer portion of the joining element (e.g., that defines part of the exterior surface of the housing) may be formed of a second material that is different from the first (e.g., a different polymer material). The materials may have different properties, which may be selected based on the different functions of the inner and outer portions of the joining elements. For example, the inner material may be configured to make the main structural connection between housing members, and may have a higher mechanical strength and/or toughness than the outer material. On the other hand, the outer material may be configured to have a particular appearance, surface finish, chemical resistance, water-sealing function, or the like, and its composition may be selected to prioritize those functions over mechanical strength. The joining elements may be formed from fiber-reinforced polymer, epoxy, or any other suitable material(s). 
     In the device  700 , at least three segments of the housing are adapted for use as antennas for communicating via the sub-6 GHz spectrum. More particularly, the housing members may be adapted for use as antennas by conductively coupling ground lines and feed lines to particular locations on the housing members (which are conductive and may be formed of or include metal). The particular location of the ground and feed lines on a housing member may in part define the particular wavelengths for which the antennas are tuned. 
     The device  700  includes one example configuration of a first group of antennas for communicating via the sub-6 GHz spectrum. The first group of antennas includes a first sub-6 GHz antenna  702 , a second sub-6 GHz antenna  704 , a third sub-6 GHz antenna  706 , and a fourth sub-6 GHz antenna  708 . In this example configuration, the first, second, and third sub-6 GHz antennas  702 ,  704 ,  706  are defined by segments of housing members, while the fourth sub-6 GHz antenna  708  is a conductive trace (e.g., on a circuit board) or other radiating element that is positioned within the device. The four antennas of the first group of antennas may be configured to operate according to a 4×4 MIMO (multiple input, multiple output) scheme. 
     The antennas that are defined by segments of the housing members may be similar to one another in structure and function. Accordingly, to avoid redundancy, only the first sub-6 GHz antenna  702  will be described in detail. However, it will be understood that the description applies equally to the second sub-6 GHz antenna  704  and the third sub-6 GHz antenna  706  as well. 
     The first sub-6 GHz antenna  702  may be defined by a portion of the housing member  701 , and more particularly, a portion of the housing member  701  that is proximate the joining element  716 . In order to send and receive electromagnetic signals from the first sub-6 GHz antenna  702 , ground and feed lines may be conductively coupled to the housing member  701 . For example, a ground line may be conductively coupled to location  712  and a feed line may be conductively coupled to location  710 . 
     The portion of the housing member  701  that acts as the first sub-6 GHz antenna  702  may define structural features  713  and  714 . These features may extend from the interior side of the housing member  701  and towards the interior volume of the device  700 . The features  713 ,  714  may have several functions, including defining physical mounting locations for the ground and feed lines, and defining interlock features with which the material of the joining elements engage and/or encapsulate to form the structural coupling between the housing members. While the features  713 ,  714  are shown in  FIG. 7  without being encapsulated by or otherwise engaged with the material of the joining element  716 , it will be understood that in some cases the material of the joining element  716  contacts, engages, and/or at least partially encapsulates the features  713  and/or the features  714 . Further, while such features are only shown on the housing members  701  and  707 , the other housing members may include similar features proximate the joining elements. 
     As noted above, the second sub-6 GHz antenna  704  and the third sub-6 GHz antenna  706  may have the same or similar structures as the first sub-6 GHz antenna  702 . In some cases, first, second, and third sub-6 GHz antennas are each configured to communicate via a different frequency band. Accordingly, the exact shape, length, or other physical characteristic of each of these antennas may differ from one another. 
     As noted above, the fourth sub-6 GHz antenna  708 , which is part of the first group of antennas that operates according to a 4×4 MIMO scheme, is a conductive trace or other radiating element that is positioned within the device. In some cases, however, a portion of the first housing member  701  that is proximate the joining element  726  may be configured to act as the fourth sub-6 GHz antenna. In such case the first housing member  701  may include structural features similar to those of the first sub-6 GHz antenna  702  (e.g., the features  713 ,  714 ), and ground and feed lines may be similarly coupled to that region of the first housing member  701  to facilitate transmitting and receiving electromagnetic signals. 
     While the sub-6 GHz antennas  702 ,  704 ,  706 , and  708  may be used to communicate via the sub-6 GHz spectrum, the device  700  may also (or instead) include antennas for communicating via the millimeter-wave spectrum. The device  700  may include, for example, a first millimeter-wave antenna  730 , a second millimeter-wave antenna  732 , and a third millimeter-wave antenna  734 . Millimeter-wave antennas may be more directional and more susceptible to attenuation from occlusion than antennas for other spectra. For example, with respect to attenuation, if a user places his or her hand over a millimeter-wave antenna, communications via that antenna may suffer or be completely ceased. With respect to directionality, if the millimeter-wave antenna is pointed more than a certain angle away from a cell tower, the antenna may cease being able to effectively communicate with that cell tower. In order to mitigate these effects, the device may include multiple millimeter-wave antennas strategically positioned to enable wireless communications in a number of different positions, locations, orientations, or the like. For example, in the device  700 , the first millimeter-wave antenna  730  may be configured as a front-fired antenna (e.g., sending and receiving electromagnetic signals primarily along a direction that is perpendicular to the front surface of the device). The second millimeter-wave antenna  732  may be configured as a rear-fired antenna (e.g., sending and receiving electromagnetic signals primarily along a direction that is perpendicular to the rear surface of the device). The third millimeter-wave antenna  734  may be configured as a side-fired antenna (e.g., sending and receiving electromagnetic signals primarily along a direction that is perpendicular to a side surface of the device). It will be understood that the directional millimeter-wave antennas need not be oriented directly at another antenna in order to communicate, but may tolerate slight misalignments (e.g., +/−15 degrees, +/−30 degrees, or another value). 
       FIG. 8A  illustrates the device  700 , showing example radiation patterns of the millimeter-wave antennas, and how those radiation patterns are oriented relative to the device  700 . For example, the first millimeter-wave antenna  730  defines a first radiation pattern  803  extending through the front surface  809  of the mobile phone  700 , the second millimeter-wave antenna  732  defines a second radiation pattern  805  extending through the rear surface  813  of the mobile phone, and the third millimeter-wave antenna  734  defines a third radiation pattern  804  extending through the side surface  811  of the mobile phone. As noted above, the millimeter-wave antennas may be directional antennas (or high gain antennas). Accordingly, the antenna gains of the millimeter-wave antennas may be highest along particular directions. For example, as shown in  FIG. 8A  and corresponding to the shapes and orientations of the radiation patterns (or lobes) of the millimeter-wave antennas, a first antenna gain of the first millimeter-wave antenna  730  is highest along a first primary transmission direction  806  (e.g., perpendicular to the front surface  809 ), a second antenna gain of the second millimeter-wave antenna  732  is highest along a second primary transmission direction  808  (e.g., perpendicular to the rear surface  813 ), and a third antenna gain of the third millimeter-wave antenna  734  is highest along a third primary transmission direction (e.g., perpendicular to the side surface  811 ). In this case, the primary transmission directions of the first and second millimeter-wave antennas  730 ,  732  are orthogonal (or substantially orthogonal) to the third millimeter-wave antenna  734 . As described below with respect to  FIGS. 8B-8D , the radiation patterns and their associated transmission directions may provide millimeter-wave reception when the device is being held or used in different orientations and/or under different use conditions. While the radiation patterns and/or antenna gains are described with respect to a primary transmission direction, it will be understood that the transmission direction does not exclusively refer to transmission operations (e.g., sending information to another device, antenna, system, or the like), and instead may encompass and/or relate to both transmitting and receiving operations. Further, while  FIG. 8A  shows a single radiation pattern for each of the first, second, and third millimeter-wave antennas, each of the millimeter-wave antennas may include multiple antenna elements, each associated with its own radiation pattern. Thus, for example, the third millimeter-wave antenna  734  may include four antenna elements, each having a radiation pattern that is similar to the third radiation pattern  804  in size, shape, gain, and/or primary transmission direction. 
       FIGS. 8B-8D  illustrate how the millimeter-wave antennas may cooperate to provide millimeter-wave communications in various different use cases.  FIG. 8B  illustrates the device  700  in a face-up position on a table  802  (which is merely representative of many surfaces that the device  700  may be placed on). In this condition, the back-fired (or rear-fired) millimeter-wave antenna  732  is facing the table surface, and thus may be occluded by the table and not oriented towards a cell tower or other remote antenna. However, the front-fired millimeter-wave antenna  730  and the side-fired millimeter-wave antenna  734  may be unobstructed (at least by the table surface). Further, because the front- and side-fired antennas are oriented in different directions (e.g., the front-fired antenna radiating generally perpendicular to the table top and the side-fired antenna radiating generally parallel to the table top), there is a greater likelihood that at least one of these antennas will be sufficiently directed at a cell tower or other remote antenna to enable wireless communications. 
       FIG. 8C  illustrates the device  700  being held in a user&#39;s hand in an upright or “portrait” orientation (e.g., with the long axis of the device  700  parallel to the height-axis of the user). In this condition, the side-fired millimeter-wave antenna  734  is occluded by the user&#39;s hand, and may thus be rendered temporarily ineffective or otherwise insufficient. However, the front-fired millimeter-wave antenna  730  and the rear-fired millimeter-wave antenna  732  may be unobstructed (at least by the user&#39;s hand). Further, because the front- and rear-fired antennas are oriented in different directions (e.g., the front-fired antenna radiating generally towards the user and possibly over the user&#39;s shoulder and/or around his or her body, and the rear-fired antenna radiating away from the user), there is a greater likelihood that at least one of these antennas will be sufficiently directed at a cell tower or other remote antenna to enable wireless communications. 
       FIG. 8D  illustrates the device  700  being held in a user&#39;s hand in a “landscape” orientation (e.g., with the long axis of the device  700  perpendicular to the height-axis of the user and/or parallel to the ground). In this condition, the rear-fired millimeter-wave antenna  732  may be occluded by the user&#39;s hand, and may thus be rendered temporarily ineffective or otherwise insufficient. However, the side-fired millimeter-wave antenna  734 , and optionally the front-fired millimeter-wave antenna  730 , may be unobstructed (at least by the user&#39;s hands). Further, because the front- and side-fired antennas are oriented in different directions (e.g., the front-fired antenna radiating generally towards the user and possibly over the user&#39;s shoulder and/or around his or her body, and the side-fired antenna radiating away from the user), there is a greater likelihood that at least one of these antennas will be sufficiently directed at a cell tower or other remote antenna to enable wireless communications. 
     Returning to  FIG. 7 , the second (rear-fired) millimeter-wave antenna  732  may be coupled to a logic board  736  (which may be an embodiment of the logic boards  220 ,  320 ,  420 ,  520 , or any other logic board described herein). In some cases, the second millimeter-wave antenna  732  (which may be or may include a passive antenna board) is surface mounted directly to the logic board  736 . The second millimeter-wave antenna  732  may include antenna arrays for two different frequencies (e.g., 28 GHz and 39 GHz, though other frequencies are also possible). Each antenna array may include four antenna elements, and each antenna element may have two different polarizations. By including two different antenna arrays, rather than using the same antenna elements for two different bands, the second millimeter-wave antenna  732  may have a greater overall bandwidth than an antenna that uses the same antenna elements to communicate over two (or more) frequency bands. The greater bandwidth of the second millimeter-wave antenna  732  may allow for greater tolerances in the positioning of the antenna  732  in the device  700  while still providing adequate antenna performance. 
     The device  700  may also include antenna circuitry in a system-in-package (SiP) component  738 . The SiP component  738 , referred to herein as the SiP  738 , may include components such as one or more processors, memory, analog-to-digital converters, filters, amplifiers, power control circuitry, or the like. The SiP  738  may be coupled to the logic board  736 , and may be positioned above the second millimeter-wave antenna  732 . The antenna elements in the second millimeter-wave antenna  732  may be conductively coupled to the SiP  738  so that the SiP  738  can process signals received via the second millimeter-wave antenna  732  and cause the second millimeter-wave antenna  732  to send signals. 
     The SiP  738  may include antenna circuitry for other antennas as well. For example, the first millimeter-wave antenna  730  may be conductively coupled to the SiP  738  via a circuit board  740  (which may be a flexible circuit element with conductive traces or other suitable conductor or set of conductors). 
       FIG. 9A  is a partial cross-sectional view of the device  700 , viewed along line  9 A- 9 A in  FIG. 7 . The cross-sectional view illustrates example details of the third (side-fired) millimeter-wave antenna  734  of the device  700 . The side-fired antenna  734  (also referred to as an antenna module) is secured to an interior of the housing  750  of the device  700 , and is configured to transmit and receive electromagnetic signals through one or more openings  901  in the side wall of the housing  750 . The openings  901  may extend through the side wall of the housing  750  and may at least partially define an antenna window for the side-fired antenna  734 . 
     The side-fired antenna  734  includes an antenna array  926 , which includes a plurality of directional antenna elements. The antenna array  926  may include antenna elements for two different frequencies (e.g., 28 GHz and 39 GHz, though other frequencies are also possible). For example, two antenna elements may be provided for each frequency, and each antenna element may have two different polarizations. Of course, other configurations of antenna elements are also possible. For example, the antenna array  926  may include four antenna elements for each frequency. 
     The side-fired antenna  734  may also include antenna circuitry in a SiP component  928 . The SiP component  928 , referred to herein as the SiP  928 , may include components such as one or more processors, memory, analog-to-digital converters, filters, amplifiers, power control circuitry, or the like. The SiP  928  may be conductively coupled to the logic board  736  (e.g., via a flexible circuit element  934 ,  FIG. 9B ). The antenna elements in the antenna array  926  may be conductively coupled to the SiP  928  so that the SiP  928  can process signals received via the antenna array  926  and cause the antenna array  926  to send signals. 
     A spacer  930  may be positioned between the SiP component  928  and a bracket  932 . The bracket  932  may secure components of the side-fired antenna  734  to the housing  750 , as shown and described in greater detail with respect to  FIG. 9B . 
     The side wall of the housing  750  (shown in  FIG. 9B ) may be configured to function as a waveguide for guiding electromagnetic signals to and from the antenna array  926 . The waveguide may be defined by a passage or hole  921  through the side wall of the housing  750 . The passage  921  may be defined in part by walls  922  that extend from an exterior side surface of the side wall of the housing  750  to an interior surface of the housing  750 . As shown, the walls  922  are angled such that the opening on the exterior side surface is offset from the opening on the interior surface of the housing. More particularly, the center of the opening in the exterior side surface of the side wall may be vertically offset from the center of the opening in the interior side of the housing  750 . 
     The vertical offset of the openings defines a generally non-horizontally aligned passage (relative to the orientation shown in  FIG. 9A ), which allows the internal components of the side-fired antenna  734  to be offset from a central axis of the device  700  while also allowing the opening  901  in the exterior side surface to be vertically centered in the exterior side surface. For example, the height  908  of the housing  750  above the opening  901  may be the same as the height  910  of the housing  750  below the opening  901 . By aligning the opening  901  with the middle of the side surface (e.g., the middle along the vertical direction), the structural integrity (e.g., stiffness, strength, etc.) of the housing  750  may be higher than if the opening  901  were offset vertically from the center of the side surface (e.g., because the amount of housing material above the opening  901  would be different from the amount below, leading to one side being weaker than the other). Further, the central alignment of the opening  901  provides an overall symmetrical and balanced appearance to the device  700 . 
     The side-fired antenna  734  may include a cover element  920  (also referred to as an insert) within part of the passage  921 . The insert  920  may be a plastic, glass, or other material (e.g., a nonconductive material) insert, and may be adhered to the antenna array  926  via an adhesive  924 . Notably, there may be no air gap between the antenna array  926  and the insert  920 . The ability to construct the side-fired antenna  734  without an air gap between the antenna array  926  and the insert  920  may be due at least in part to the particular materials and other properties of the adhesive  924  and the insert  920 . The insert  920  may be placed into the passage  921 , or it may be formed in place by, for example, injecting a polymer material into the passage  921  and allowing the polymer material to cure or otherwise harden. 
     The device  700  may also include a cover element  912  positioned in the passage  921  and defining part of the exterior side surface of the device  700  (e.g., in conjunction with the exterior side surface of the housing  750 ). The cover element  912  may be formed of glass, sapphire, glass-ceramic, plastic, or any other suitable material (e.g., nonconductive material). The thickness of the cover element  912  may be determined at least in part on the material being used and the effect of the material (and the dimensions) on the electromagnetic signals passing through the passage  921 . For example, in order to achieve the same or similar electromagnetic performance, the thickness of the cover element  912  may be greater if it is formed of glass than if it is formed from sapphire. If the cover element  912  is formed of sapphire, a spacer layer (e.g., a plastic, epoxy, or other suitable material) may be included between the cover element  912  and an adhesive (e.g., the adhesive  924 ) that secures the cover to the device  700 . 
     The cover element  912  may include a mask layer  914 , which may be applied to the back or front surface of the cover element  912 . As shown, the mask layer  914  is applied to the back surface of the cover element  912 . The mask layer  914  may be an ink, dye, film, paint, coating, or other material, and may be visible through the cover element  912 . The mask layer  914  may be opaque. The mask layer  914  may also be a single layer, or it may include multiple sub-layers. 
     The cover element  912  may be secured to the housing  750  via an adhesive  916 , and a sealing material  918  may be positioned over the seam between the insert  920  and the walls of the passage  921 . The adhesive  916  may also adhere the cover element  912  to the insert  920 . 
     The sealing material  918  may be a polyurethane or any other suitable sealing material, and may be configured to prevent or limit ingress of liquids (e.g., water, sweat, etc.) and/or other contaminants into the device  700  through the seam. The sealing material  918  may be applied as a continuous sheet over the insert  920  and the surfaces of the housing that surround the insert  920 . A central portion of the sealing material  918  may then be removed (e.g., by laser ablation or another suitable technique) to reveal a surface of the insert  920  to which the adhesive  916  may be applied. The adhesive  916  may be a film, a liquid, or any other suitable adhesive. 
     The passage  921  may include a recess  923  that accommodates part of the sealing material  918 . In particular, the recess  923  may be configured so that the seam between the insert  920  and the housing material is substantially flat or planar, thus defining a flat surface on which to apply the sealing material  918 . The recess  923  may be formed by machining, using a T-slot bit. 
       FIG. 9B  is an exploded view of the side-fired antenna  734 , illustrating additional details of the configuration of the antenna  734  and its components and the antenna window formed in the side wall of the housing  750 . As described above, the side-fired antenna  734  includes a cover element  912 , a mask layer  914  (which may be applied to the cover), an adhesive  916 , a sealing material  918 , an additional cover element  920  (or insert), an adhesive  924 , an antenna array  926 , a SiP  928 , a flexible circuit element  934  (coupled to the antenna array  926  and/or SiP  928  via an electrical connector  940 ), a spacer  930 , and a bracket  932 . 
     In some cases, the housing includes multiple passages or holes  921  extending through the side wall of the housing  750  and at least partially defining the antenna window for the side-fired antenna. The holes  921  may be formed along a bottom surface of a recessed region  925 , as shown. For example, the cover element  912 , mask layer  914 , adhesive  916 , and sealing material  918  may be positioned within the recessed region  925 . 
     Each passage or hole  921  may include its own insert  920 , and may be associated with a single antenna element in the antenna array  926 . More particularly, for each respective passage  921 , the antenna array  926  may include a respective antenna element aligned with that passage. In this way, the passages, which act as waveguides for the antenna elements, may direct electromagnetic signals to and from individual antenna elements. The passages  921  may be separated from adjacent passages by ribs  948 . The ribs  948  may be formed by removing material from the housing  750  to define the passages and the ribs. Accordingly, the ribs  948  may be integral with (e.g., formed from the same block of material as) the rest of the housing member in which the passages are formed. In other cases, the ribs may be separate components that are attached to the housing  750 . In some cases, the ribs may be omitted, and a single hole or passage may be defined through the side wall to facilitate antenna operation (e.g., transmitting and receiving electromagnetic signals through the side wall of the housing  750 ). 
     The device  700  may also include a set of anchor members  942 . The anchor members  942  may include alignment features (e.g., posts) that are configured to engage with corresponding alignment features (e.g., blind holes) in the housing  750 . When engaged with the housing  750 , the anchor members  942  may provide surfaces and/or other features that guide or align the components of the side-fired antenna  734  in a target location and/or position. 
     A ground path may be defined from the housing  750  to the electrical components of the side-fired antenna  734 , such as the antenna array  926  and SiP  928 , to provide an electrical ground to the side-fired antenna  734 . For example, a fastener  936 , which may be conductive, may be threaded into the housing  750 , thereby conductively coupling the fastener  936  to the housing  750  (which may define an electrical ground plane of the device  700 ). The flexible circuit element  934  may include a grounding and attachment lug  938 , which may include a hole through the flexible circuit element and a conductive material that surrounds or is proximate the hole. The fastener  936  extends through the hole of the grounding and attachment lug  938  and contacts the conductive material of the grounding and attachment lug  938  when the fastener  936  is installed, thereby conductively coupling the conductive material of the grounding and attachment lug  938  (which may be conductively coupled to or otherwise define an electrical ground of the flexible circuit element  934 ) to the housing  750 . In this way, a ground path may be established between the flexible circuit element  934  and the housing  750 . The conductive material of the grounding and attachment lug  938  may also contact one of the anchor members  942 , which is in turn conductively coupled to the housing  750 . Thus, the ground path from the flexible circuit element  934  to the housing may also be defined by or via the anchor member  942 . 
     The fasteners  936  may be any suitable fasteners, such as screws, and may also retain the components of the side-fired antenna  734  in position. More particularly, the bracket  932 , which is held in place by the fasteners  936 , may capture and retain components of the antenna  734  between itself and the housing  750 . The bracket  932  may also act as a heat sink or otherwise serve to spread and/or dissipate heat from the antenna components. 
       FIG. 10A  is a partially exploded view of the first (front-fired) millimeter-wave antenna  730  (also referred to as an antenna module). The front-fired antenna  730  may include four antenna elements  1002 ,  1004 ,  1006 , and  1008 . The antenna elements  1002 ,  1004 ,  1006 , and  1008  may be directional antenna elements that define radiation patterns with their highest gains along primary transmission directions, as described with respect to  FIG. 8A . The primary transmission directions of the antenna elements  1002 ,  1004 ,  1006 , and  1008  may be parallel to one another, and may extend through the front cover of a device (or any cover or wall of the device that they are positioned below). 
     The antenna elements  1002 ,  1004 ,  1006 , and  1008  may be formed from a dielectric material such as zirconia (or another suitable ceramic or other material). In some cases, the antenna elements may be formed of a material having a dielectric constant (also referred to as relative permittivity) higher than about 20. In some cases, the dielectric constant is between about 21 and about 24, or between about 27 and about 30. In cases where the antenna elements  1002 ,  1004 ,  1006 , and  1008  are ceramic, they may be referred to as ceramic posts. 
     The four directional antenna elements of the front-fired antenna  730  may include two first directional antenna elements  1002 ,  1004  configured to operate at a first frequency band (e.g., 28 GHz), and two second directional antenna elements  1006 ,  1008  configured to operate at a second frequency band (e.g., 39 GHz). The size and shape of the antenna elements may define the resonant frequency or frequency band for the antenna elements. Thus, for example, the first antenna elements  1002 ,  1004  may have a different (e.g., greater) size in the x-dimension and in the y-dimension than the second antenna elements  1006 ,  1008 , thus causing the first and second antenna elements to have different resonant frequencies and thereby communicate on different frequency bands. In some cases, the x- and y-dimensions of the first antenna elements  1002 ,  1004  are about 1.1 mm by about 1.1 mm, and the x- and y-dimensions of the second antenna elements  1006 ,  1008  are about 0.8 mm by about 0.8 mm. 
     The antenna elements of the front-fired antenna  730  may include conductive contact pads, such as the conductive contact pads  1012 ,  1014  on the antenna element  1008 . (While not separately labeled, similar conductive contact pads may be provided on the other antenna elements  1002 ,  1004 , and  1006  as well.) The conductive contact pads may be configured to conductively couple the antenna elements to other antenna circuitry (e.g., via conductors in the circuit board  740 ). For example, the conductive contact pads may be soldered to the circuit board  740 . 
     The conductive contact pads may be formed by metallizing the antenna elements, such as with electroplating, metal deposition (e.g., plasma vapor deposition, chemical vapor deposition), or any other suitable technique. In some cases, a metal or conductive film is applied to the antenna elements to form the conductive contact pads. In some cases, the height of the conductive contact pads in the z-dimension may affect the tuning of the antenna elements (e.g., the resonant frequency of the antenna element, the efficiency of the antenna element, etc.). In some cases, the other dimensions of the conductive contact pads (e.g., a thickness, a width) may differ between the antenna elements as well. While only two conductive contact pads are visible on each antenna element, the non-visible sides of the antenna elements may also include conductive contact pads (e.g., opposite the visible conductive contact pads). In some cases where four conductive contact pads are provided, only two conductive contact pads (e.g., two non-parallel contact pads) are used to conductively couple the antenna element to other antenna circuitry. 
     Each antenna element may have two polarizations, with the conductive contact pads providing the signals to and from the antenna elements for the different polarizations. For example, a first conductive contact pad  1012  may be configured to excite the second antenna element  1008  according to a first polarization, while the second conductive contact pad  1014  may be configured to excite the second antenna element  1008  according to a second polarization (e.g., orthogonal to the first polarization). This configuration may allow each antenna element to simultaneously send and/or receive two separate electromagnetic signals. 
     As noted above, the first antenna elements  1002 ,  1004  may operate at different frequencies than the second antenna elements  1006 ,  1008 . The use of multiple antenna elements for each frequency may facilitate techniques such as beam-forming. To facilitate beam-forming operations, the antenna elements that share the same frequency may be separated from one another by a particular distance. For example, the first antenna elements  1002 ,  1004  may be separated by a distance  1005 , and the second antenna elements  1006 ,  1008  may be separated by a distance  1007 , which may be different than the distance  1005  (e.g., less than or greater than the distance  1005 ). In some cases, the distances (e.g., the gaps) between the antenna elements is not uniform. The particular distances may be defined at least in part on the frequencies on which the antenna elements operate, operational parameters of a wireless communication protocol, or the like. 
     The antenna elements  1002 ,  1004 ,  1006 , and  1008  may be at least partially encapsulated or encased in a cover structure  1010 . The cover structure  1010  may be a molded polymer material (e.g., a fiber-reinforced polymer), and it may provide structural support to the antenna elements. The cover structure  1010  may be molded around the antenna elements after they are attached to the circuit board  740 , or it may be formed separately and then attached to the circuit board  740  (either before or after the antenna elements are connected to the circuit board  740 ). In some cases, the cover structure  1010  contacts substantially all of the surfaces of the antenna elements. In some cases, the cover structure  1010  defines air gaps between adjacent antenna elements, such as by defining one or more cavities within the cover structure  1010 .  FIG. 10C  illustrates an example front-firing antenna with a cover structure  1010  that defines air gaps between adjacent antenna elements. 
       FIG. 10B  illustrates another example of a front-firing antenna  1020 . In this example, instead of metallizing the antenna elements to produce the conductive contact pads, conductive contacts  1026  may be attached to the circuit substrate  1028  (which may be similar to the circuit board  740 , and may be a flexible circuit element with conductive traces or other suitable conductor or set of conductors). The antenna elements  1024 , which may lack the conductive contact pads but be otherwise similar to the antenna elements  1002 ,  1004 ,  1006 , and  1008 , may be coupled to the circuit substrate  1028  after the conductive contacts  1026  are attached. The conductive contacts  1026  may be attached to the circuit substrate  1028  prior to the antenna elements  1024  being attached and prior to the cover structure  1022  (which may be similar to the cover structure  1010 ) being attached or formed around the antenna elements  1024 . Alternatively, the conductive contacts  1026  may be integrated with the cover structure  1022  (e.g., by insert molding the cover structure  1022  around the conductive contacts  1026  to at least partially encapsulate the conductive contacts  1026 ), and then the cover structure  1022  with the conductive contacts  1026  may be attached to the circuit substrate  1028 . The conductive contacts  1026  may have different sizes, and the sizes may at least partially define or affect the tuning of the antenna elements. For example, the height of the conductive contacts  1026  in the z-dimension (e.g., the height of the portion of the conductive contacts  1026  that is in contact with the side of the antenna element) may affect the tuning of the antenna elements (e.g., the resonant frequency of the antenna element, the efficiency of the antenna element, etc.). Accordingly, the conductive contacts  1026  on the antenna elements that are configured to operate at one frequency may have different dimensions than those on the antenna elements that are configured to operate at a different frequency. In some cases, the other dimensions of the conductive contacts  1026  (e.g., a thickness, a width) may differ between the antenna elements as well. 
       FIG. 10C  is a partially exploded view of another example (front-fired) millimeter-wave antenna  1037 . The front-fired antenna  1037  may include antenna elements  1034  (which may be embodiments of other antenna elements described herein, such as the antenna elements  1002 ,  1004 ,  1006 , and  1008 . The front-fired antenna  1037  may also include a cover structure  1030 , which may be similar in materials and function to other cover structures described herein, such as the cover structures  1010 ,  1022 . The cover structure  1030  may define air gaps  1031  between adjacent antenna elements  1034 . Because air has a lower dielectric constant than many materials, such as a plastic from which the cover structure  1030  may be formed, the air gaps  1031  may help reduce the average or effective dielectric constant between the antenna elements. In some cases, the presence of, as well as the sizes and shapes of, the air gaps  1031  may improve the operation of the antenna as compared to a cover structure without air gaps. The air gaps  1031  may also allow the spacing between the antenna elements  1034  to be reduced, relative to a solid cover structure, resulting in a smaller overall size of the antenna  1037  as compared to other constructions. 
     The antenna  1037  may be formed by a molding process. For example, an antenna element subassembly may be formed by a process in which conductive contacts  1038  (which may be embodiments of the conductive contacts  1026 ) and the antenna elements  1034  are placed in a first mold such that the conductive contacts  1038  are in contact with the antenna elements  1034  at a target location and position (e.g., as shown in  FIGS. 10A and/or 10B ). A first polymer material may then be introduced into the first mold to partially encapsulate the conductive contacts  1038  and at least partially surround the antenna elements  1034 . The first polymer material may be allowed to cure or otherwise harden to form retention structures  1036 . The retention structures may secure the conductive contacts  1038  in position and in contact with the antenna elements  1034 . 
     The antenna element subassemblies may then be placed into a second mold, along with a mounting tab  1032 , and a second polymer material (which may be different from the first polymer material and may be injected at a temperature that is lower than a melting or softening temperature of the first polymer material) may be injected into the second mold to form the cover structure  1030 . The second polymer material may be allowed to cure or otherwise harden, thereby retaining the antenna element subassemblies together and in their target orientations and positions (e.g., with the appropriate spaces between the antenna elements  1034 ). The mounting tab  1032  may be configured to engage a screw or other fastener to assist in retaining the antenna  1037  in an intended position in a device. 
     As shown in  FIG. 10C , the retention structures  1036  may define holes  1039  that extend through the retention structures  1036  and expose the conductive contacts  1038 . While only two holes are labeled in  FIG. 10C , each retention structure  1036  may define one hole for each conductive contact  1038  that it at least partially encapsulates. The holes may result from the presence, during the first molding operation, of tools that apply a force to the conductive contacts  1038  to retain the conductive contacts  1038  in contact with the antenna elements  1034  during the molding operation. After the first polymer material is introduced into the first mold (and optionally after the first polymer material is cured and/or hardened), the tools may be removed to reveal the holes  1039 . The holes may be used to inspect the antenna element subassemblies. For example, a measuring tool (e.g., a laser) may be directed onto the conductive contacts  1038  through the holes, as well as onto the exposed surfaces of the antenna elements  1034 , to determine a position differential. If the position differential for a given conductive member is greater than a thickness of the conductive member, it may be assumed that there is an air gap between the conductive member and the surface of the antenna element  1034  to which the conductive member is intended to contact. If the position differential is too great (e.g., if an air gap is likely to exist), the antenna element subassembly may be rejected. 
       FIG. 10D  is a side view of the antenna  1037 . As shown in  FIG. 10D , the widths of the air gaps  1031  are not uniform, and their sizes may be selected based on their effect on antenna performance, tuning, and/or other properties. For example, as the dielectric properties of the materials between antenna elements may affect the operation of the antenna, the sizes of the air gaps  1031  may be selected in order to produce a desired dielectric performance (e.g., average or effective dielectric constant) between the antenna elements. 
       FIG. 10E  shows a bottom view of the antenna  1037 . As shown in  FIG. 10E , the retention structures  1036  extend around the antenna elements  1034  and hold the conductive contacts  1038  in place against the antenna elements  1034 . Further, the conductive contacts  1038  are exposed along the bottom of the antenna  1037  so that they can be conductively coupled to another component, such as the circuit substrate  1028 . 
     Other techniques may also be used to produce millimeter wave antennas such as those described with respect to  FIGS. 10A-10E . For example, a clamshell-like cover structure may be formed prior to insertion of the antenna elements. The antenna elements (or antenna element subassemblies) may thereafter be introduced into position and the clamshell cover structure may be closed to at least partially encapsulate the antenna elements (or antenna element subassemblies). As another example, the conductive contacts and the cover structure (and optionally retention structures and a mounting tab) may be formed together into a cover structure subassembly (e.g., by insert molding), and the antenna elements may thereafter be introduced (e.g., press-fit) into openings defined in the cover structure subassembly. 
     As noted above, portions of a metal or conductive housing of a device may be used as antenna elements to send and receive wireless signals. More particularly, the portions of the metal or conductive housing may act as the radiating elements of antennas.  FIG. 7 , for example, shows an example device  700  that uses metal housing members to define antenna elements for the sub-6 GHz spectrum. Metal housing members may be used to define antenna elements for other frequencies and/or protocols in addition to the sub-6 GHz antennas described with respect to  FIG. 7 .  FIG. 11  is a schematic representation of a portion of a housing  1100  formed of multiple conductive housing members joined together with joining elements.  FIG. 11  also schematically represents example connection points on the housing members where feed and/or ground lines may be conductively coupled to the housing members to carry electromagnetic signals from the housing member to other antenna circuitry (and from the antenna circuitry to the housing member). 
     As shown in  FIG. 11 , the housing  1100  may include a first housing member  1102  that defines a portion of a first side surface  1142  as well as a first corner surface  1150  and part of a second side surface  1144 . The first housing member  1102  is structurally coupled to a second housing member  1104  via a first joining element  1114 . As noted above, joining elements, such as the joining element  1114 , may be formed from a polymer material (e.g., a fiber-reinforced polymer) that can structurally join housing members while also providing sufficient electrical isolation between the housing members to allow them to act as antenna elements. 
     The housing  1100  also includes a second housing member  1104  that defines a portion of the second side surface  1144  and is structurally coupled to a third housing member  1106  via a second joining element  1116 . The third housing member  1106  defines part of the second side surface  1144  as well as a second corner surface  1152 . 
     The third housing member  1106  also defines part of a third side surface  1146  of the housing and is structurally connected to a fourth housing member  1108  via a third joining element  1118 . The fourth housing member  1108  also defines a portion of the third side surface  1146 , a third corner surface  1154 , and part of the fourth side surface  1148 . 
     The fourth housing member  1108  is coupled to a fifth housing member  1110  via a fourth joining element  1120 . The fifth housing member  1110  defines a portion of the fourth side surface  1148  and is coupled to a sixth housing member  1112  via a fifth joining element  1122 . The sixth housing member  1112  defines a portion of the fourth side surface  1148 , a fourth corner surface  1156 , and a portion of the first side surface  1142 . The sixth housing member  1112  is structurally connected to the first housing member  1102  via a sixth joining element  1125 . 
     Each of the joining elements of the housing  1100  may define a portion of an exterior surface of the housing  1100 . Thus, the exterior side surfaces of the housing  1100  may be defined entirely or substantially entirely by the housing members and the joining elements. 
     In order to operate as antenna elements, the housing members of the housing  1100  may be conductively coupled to antenna circuitry, electrical ground planes, and the like. The particular locations of the connection points on the housing members, as well as the sizes and shapes of the housing members, may at least partially define parameters of the antenna elements. Example antenna parameters may include resonant frequency, range, radiation pattern, efficiency, bandwidth, directivity, gain, or the like. 
       FIG. 11  illustrates example positions for the connection points of feed and ground lines to the housing members. For example, feed and ground lines may be conductively coupled to the first housing member  1102  at connection points  1124 - 1 ,  1124 - 2 , thereby facilitating wireless communication via the first housing member  1102 . 
     Feed and ground lines may be conductively coupled to the second housing member  1104  at connection points  1128 - 1 ,  1128 - 2  and optionally at connection points  1126 - 1 ,  1126 - 2 . The portion of the second housing member  1104  between or proximate the connection points  1126 - 1 ,  1126 - 2  may act as one antenna element, while the portion of the second housing member  1104  between or proximate the connection points  1128 - 1 ,  1128 - 2  may act as another, independent antenna element (e.g., it may send and receive electromagnetic signals independently of the antenna element between the connection points  1126 - 1 ,  1126 - 2 , despite being defined by the same housing member  1102 ). While  FIG. 11  illustrates connection points  1126 - 1 ,  1126 - 2 , these may be omitted in some implementations, such as in the device  700  of  FIG. 7 , which uses a conductive element on a circuit board as an antenna element in that corner of the device instead of using a housing member. 
     Feed and ground lines may be conductively coupled to the third housing member  1106  at connection points  1130 - 1 ,  1130 - 2 , and to the fourth housing member  1108  at connection points  1132 - 1 ,  1132 - 2  and connection points  1134 - 1 ,  1134 - 2 . The fourth housing member  1108  may define different antenna element configurations depending on which feed and ground lines are used at a given time. For example, in a first mode, the connection points  1132 - 1 ,  1132 - 2  are used, such that the fourth housing member  1108  is configured to communicate via a first communications protocol (or frequency), and in a second mode, the connection points  1134 - 1 ,  1134 - 2  are used, such that the fourth housing member  1108  is configured to communicate via a second communications protocol (of frequency) that differs from the first. 
     Feed and ground lines may be conductively coupled to the fifth housing member  1110  at connection points  1136 - 1 ,  1136 - 2 , and at connection points  1138 - 1 ,  1138 - 2 . Similar to the configuration of the second housing member  1104 , the portion of the fifth housing member  1110  between or proximate the connection points  1136 - 1 ,  1136 - 2  may act as one antenna element, while the portion of the fifth housing member  1110  between or proximate the connection points  1138 - 1 ,  1138 - 2  may act as another, independent antenna element (e.g., it may send and receive electromagnetic signals independently of the antenna element between the connection points  1136 - 1 ,  1136 - 2 , despite being defined by the same housing member  1110 ). Feed and ground lines may also be conductively coupled to the sixth housing member  1112  at connection points  1140 - 1 ,  1140 - 2 . 
     As noted above, the housing members of the herein described device housings may be used to form multiple groups or sets of antennas, with each group or set communicating via a different communication protocol or frequency band. For example, the housing may define multiple antennas of a first MIMO antenna array or group (e.g., for a 4G communication protocol) as well as multiple antennas of a second MIMO antenna array (e.g., for a 5G communication protocol). In one non-limiting example configuration, the antenna elements defined by the connection points  1124 ,  1130 ,  1132 ,  1134 , and  1140  may be configured to operate as part of a first MIMO antenna array (e.g., for a 4G communication protocol), while the antenna elements defined by the connection points  1126  (if provided),  1128 ,  1136 , and  1138  may be configured to operate as part of a second MIMO antenna array (e.g., for a 5G communication protocol). For any given antenna group, the antenna elements of that group do not all need to be housing members. For example, the second MIMO antenna array or group may use an internal antenna (e.g., the antenna  708 ,  FIG. 7 ) as one of the antennas in a 4×4 MIMO array. 
     As described above, conductive housing members, which may act as a radiating structure of an antenna or antenna system, may be structurally coupled together via joining elements. The joining elements may be formed from a polymer material or other dielectric material that can provide sufficient electrical isolation between housing members to facilitate the use of the housing members as radiating structures for antennas. In some cases, the joining elements include one, two, or more molded elements, which are molded into a gap between the housing members and into engagement with the housing members. Because the joining elements structurally retain housing members together, a strong engagement between the joining elements and the housing members may be preferred. Accordingly, the housing members may include or define structures and/or features that a joining element engages in order to retain the joining element to the housing members, and thereby retain the housing members together. 
       FIG. 12A  illustrates an example housing member  1200  that includes features with which a joining element may engage. The portion of the housing member shown in  FIG. 12A  may correspond generally to the area  12 A- 12 A in  FIG. 7 . 
     The housing member  1200  may be formed from or include a conductive material, such as stainless steel, aluminum, a metal alloy or the like, and may be conductively coupled to an antenna circuit (e.g., via feed and/or ground lines, as described above) to act as a radiating structure for a device. The portion of the housing member  1200  shown in  FIG. 12A  may abut and/or engage with a joining element, as shown in  FIG. 12B . 
     The housing member  1200  defines a first interlock feature  1202  that extends inwardly (e.g., towards an interior of the device) from a sidewall  1201  defined by the housing member  1200 . The first interlock feature  1202  may extend from an interior side  1205  of the housing member  1200 , where the interior side  1205  is opposite an exterior side  1203 . 
     The sidewall  1201  may define an exterior surface of the device of which the housing member  1200  is a part. The first interlock feature  1202  may define a first hole  1204  and one or more second holes  1206 . When a joining element is formed by injecting or otherwise molding a moldable material against the housing member  1200 , the moldable material may at least partially surround and/or encapsulate the first interlock feature  1202 , and may flow into and optionally through the first and second holes  1204 ,  1206 . By at least partially encapsulating the interlock feature  1202  and flowing into and/or through the first and second holes  1204 ,  1206 , the joining elements may be structurally interlocked with the housing member  1200 , thereby securely retaining the joining element to the housing member  1200 . 
     The housing member  1200  may also define a second interlock feature, such as a recess  1210 , which may be an indentation, cavity, or other similar feature that is recessed relative to an end surface  1208  of the housing member  1200 . The end surface  1208  of the housing member  1200  may be the portion of the housing member  1200  that extends closest to another housing member to which the housing member  1200  is coupled via a joining element. The end surface  1208  may be offset from an end surface  1209  defined by the first interlock feature  1202 . More particularly, the end surface  1209  may be recessed relative to the end surface  1208  (e.g., along a direction that is perpendicular to the end surfaces  1208 ,  1209 ). 
     The recess  1210  may have a depth between about 100 microns and about 1000 microns, and may have a width (e.g., the left-to-right dimension as depicted in  FIG. 12A ) between about 100 microns and about 400 microns, and a length (e.g., the top-to-bottom dimension as depicted in  FIG. 12A ) between about 750 microns and about 3000 microns. In some cases, the housing member  1200  may also define pores along the end surface  1208  and/or the end surface  1209 . The pores may be formed on the end surfaces  1208  and/or  1209 , and may also be formed on the surface of the recess  1210 . The pores may be a distinct structure than the recess  1210 . For example, the recess  1210  may have a length dimension greater than about 1000 microns and a width dimension greater than about 100 microns, while the pores may have length and/or width dimensions less than about 10 microns. Similarly, the recess  1210  may have a depth greater than about 100 microns, while the pores may have a depth less than about 10 microns. In some cases, the pores are formed by chemical etching, abrasive blasting, laser or plasma etching, or the like. The material of the joining element may extend or flow into the pores during formation of the joining element and engage and/or interlock with the pores to secure the joining element to the housing member  1200 . In some cases, the pores are formed after the recess  1210  is formed, such that the pores are present on the surface of the recess  1210 . In other cases, the pores are formed prior to formation of the recess  1210 , such that the surface of the recess  1210  lacks the pores, or has a different surface morphology and/or topography than the end surface on which the pores are formed (e.g., the end surface  1208  may have pores from a chemical etching, while the recess  1210  may have machine marks from a machining process). In some cases, the largest dimension (e.g., length, width, depth) of the pores is at least an order of magnitude smaller than the largest dimension (e.g., length, width, depth) of the recess  1210 . 
     The housing member  1200  may define a flange portion  1207  that is adjacent to and/or extends along a peripheral side of a top module (which may include a cover member, a display, touch-sensing components, and the like). In some cases, the second interlock feature  1210  (e.g., the recess, as shown) is positioned in the flange portion  1207 , thereby reinforcing the portion of the joint that is along the side of the top module. More particularly, the flange portion  1207  may define a cantilever that extends away from the first interlock feature  1202 , and the second interlock feature  1210  may provide a supplemental interlocking engagement with a joining element to help prevent or limit separation or detachment of the flange portion  1207  from the joining element (e.g., the joining element  1212 ,  FIG. 12B ). The flange may extend along a direction (e.g., the vertical direction in  FIG. 12A , which may be parallel to an exterior side surface defined by the housing member  1200  and/or perpendicular to the front surface defined by a cover member of the device), and the second interlock feature  1210  may be an elongate recess or channel with a longitudinal axis that extends parallel to the exterior side surface of the housing member (e.g., along the same direction that the flange extends from the first interlock feature  1202 ). 
     When a moldable material is flowed into place (e.g., between the housing member  1200  and another housing member) to form a joining element, the moldable material may flow into and at least partially fill the recess  1210 , thereby forming a corresponding protrusion in the moldable material. When the moldable material is then cured or otherwise hardened, the protrusion of the joining element and the recess  1210  interlock with one another. The interlock between the recess  1210  and the protrusion may help prevent separation of the joining element and the housing member  1200 . Further, the position of the recess  1210  relative to the exterior surface defined by the sidewall  1201  may help improve the structural rigidity of the joint and help maintain the alignment (and mechanical coupling) between the housing member  1200 , the joining element, and the adjoining housing member in the event of a drop or other impact event. For example, while the first interlock feature  1202  may provide substantial structural strength to the interface between the joining element and the housing member  1200 , its position is further inboard (e.g., relatively nearer the internal volume of a housing) than the recess  1210 . By contrast, the further outboard position of the recess  1210  (e.g., relatively nearer the external surface of the housing member  1200 ) may improve the strength and stability of the alignment between the exterior surfaces of the housing members and the joining element. 
       FIG. 12B  is a partial cross-sectional view of the housing member  1200  (joined to another housing member  1216  via a joining element  1212 ), viewed along line  12 B- 12 B in  FIG. 12A . The joining element  1212  may be positioned between and in contact with the end surface  1208  of the housing member  1200  and a corresponding end surface  1217  of the housing member  1216 . The joining element  1212  may also extend into and interlock with the recess  1210  of the housing member  1200 , as well as a recess  1214  defined by the housing member  1216 . In addition to the mechanical interlocking between the joining element  1212  and the recesses  1210 ,  1214  (and/or other retention structures and/or interlock features), the moldable material of the joining element  1212  may form a chemical or other adhesive bond with the material of the housing members  1200 ,  1216 . 
     The exterior surfaces of the joining element  1212  and the housing members  1200 ,  1216  may define a smooth continuous exterior surface  1213  of the housing. For example, any gaps, seams, or other discontinuities between the joining element  1212  and the housing members  1200 ,  1216  along the exterior surface  1213  of the housing may be undetectable to the touch and/or to the unaided eye. For example, a fingernail sliding along the exterior surface  1213  may not catch on the seam between the joining element  1212  and the housing members  1200 ,  1216 . In some cases, any gap, seam, or other discontinuity between the joining element  1212  and the housing members  1200 ,  1216  may be less than about 200 microns, less than about 100 microns, less than about 50 microns, less than about 20 microns, or less than about 10 microns (in depth, length, offset, and/or other dimension). The interlock between the joining element  1212  and the recesses  1210 ,  1214  may help prevent or inhibit relative motion between the housing members  1200 ,  1216  and the joining element  1212 , such as relative motion of these components along a vertical direction (as oriented in  FIG. 12B ). Accordingly, the recesses  1210 ,  1214  may help maintain the substantially seamless texture and appearance between the joining element  1212  and the housing members  1200 ,  1216 . 
       FIG. 12C  illustrates another example housing member  1220  that includes features with which a joining element may engage. The housing member  1220  may be formed from or include a conductive material, such as stainless steel, aluminum, a metal alloy or the like, and may be conductively coupled to an antenna circuit (e.g., via feed and/or ground lines, as described above) to act as a radiating structure for a device. The portion of the housing member  1220  shown in  FIG. 12C  may abut and/or engage with a joining element, as shown in  FIG. 12D . 
     The housing member  1220  defines a first interlock feature  1222  that extends inwardly (e.g., towards an interior of the device) from a sidewall  1221  defined by the housing member  1220 . The first interlock feature  1222  may extend from an interior side of the housing member  1220  (e.g., analogous to the interior side  1205 ,  FIG. 12A ), where the interior side is opposite an exterior side (e.g., analogous to the exterior side  1203 ,  FIG. 12A ). 
     The sidewall  1221  may define an exterior surface of the device of which the housing member  1220  is a part. The first interlock feature  1222  may define a first hole  1224  and one or more second holes  1226 . When a joining element is formed by injecting or otherwise molding a moldable material against the housing member  1220 , the moldable material may at least partially surround and/or encapsulate the first interlock feature  1222 , and may flow into and optionally through the first and second holes  1224 ,  1226 . By at least partially encapsulating the interlock feature  1222  and flowing into and/or through the first and second holes  1224 ,  1226 , the joining elements may be structurally interlocked with the housing member  1220 , thereby securely retaining the joining element to the housing member  1220 . 
     The housing member  1220  may also define a protruding feature  1230 , which may be a post, pin, or have any other suitable shape or configuration that protrudes or extends from an end surface  1228  of the housing member  1220 . The end surface  1228  of the housing member  1220  may be the portion of the housing member  1220  that, with the exception of the protruding feature  1230 , extends closest to another housing member to which the housing member  1220  is coupled via a joining element. 
     The protruding feature  1230  may operate in a similar manner as the recess  1210  in  FIGS. 12A-12B . For example, when a moldable material is flowed into place (e.g., between the housing member  1220  and another housing member) to form a joining element, the moldable material may flow around the protruding feature  1230  to at least partially encapsulate the protruding feature  1230 . When the moldable material is then cured or otherwise hardened, the protruding feature  1230  and the recess in the moldable material that is formed around the protruding feature  1230  interlock with one another. The interlock between the protruding feature  1230  and the moldable material may help prevent separation of the joining element and the housing member  1220 . Further, the position of the protruding feature  1230  relative to the exterior surface defined by the sidewall  1221  may help improve the structural rigidity of the joint and help maintain the alignment (and mechanical coupling) between the housing member  1220 , the joining element, and the adjoining housing member in the event of a drop or other impact event. For example, while the first interlock feature  1222  may provide substantial structural strength to the interface between the joining element and the housing member  1220 , its position is further inboard (e.g., relatively nearer the internal volume of a housing) than the protruding feature  1230 . By contrast, the further outboard position of the protruding feature  1230  (e.g., relatively nearer the external surface of the housing member  1220 ) may improve the strength and stability of the alignment between the exterior surfaces of the housing members and the joining element. 
     In some cases, the housing member  1220  may also define pores along the end surface  1228  and/or the end surface  1229 . The pores may be formed on the end surfaces  1228  and/or  1229 , and may also be formed on the surface of the protruding feature  1230 . The pores may be a distinct structure than the protruding feature  1230 . For example, the protruding feature  1230  protrudes by a distance greater than about 100 microns, and may have a length and width dimension greater than about 100 microns, while the pores may have depth, length and/or width dimensions less than about 10 microns. In some cases, the pores are formed by chemical etching, abrasive blasting, laser or plasma etching, or the like. The material of the joining element may extend or flow into the pores during formation of the joining element and engage and/or interlock with the pores to secure the joining element to the housing member  1220 . In some cases, the pores are formed after the protruding feature  1230  is formed, such that the pores are present on the surfaces of the protruding feature  1230 . In other cases, the surfaces of the protruding feature  1230  lack the pores, or have a different surface morphology and/or topography than the end surface on which the pores are formed. In some cases, the largest dimension (e.g., length, width, depth) of the pores is at least an order of magnitude smaller than the largest dimension (e.g., length, width, depth) of the protruding feature  1230 . 
       FIG. 12D  is a partial cross-sectional view of the housing member  1220  (joined to another housing member  1225  via a joining element  1232 ), viewed along line  12 D- 12 D in  FIG. 12C . The joining element  1232  may be positioned between and in contact with the housing members  1220 ,  1225 . The joining element  1232  may also at least partially (and optionally fully) encapsulate the protruding feature  1230 . As can be seen in  FIG. 12D , the protruding feature  1230  may extend and/or be adjacent to two offset surfaces. For example, with respect to the housing member  1220 , the two offset surfaces include the end surface  1228  and an additional end surface  1229 . The protruding feature  1230  may extend a first distance from the end surface  1228 , and a second (greater) distance from the additional end surface  1229 . A similar structure may be used on the housing member  1225  (e.g., a protruding feature  1236  extending a first distance from an end surface  1238  and a second (greater) distance from an additional surface  1234 ). Thus, as shown in  FIG. 12D , the end surfaces  1228 ,  1238  may be closer together than the additional end surfaces  1229 ,  1234  (and the ends of the protruding features  1230 ,  1236  may be the portions of the housing members  1220 ,  1225  that are closest together). In addition to the mechanical interlocking between the joining element  1232  and the protruding features  1230 ,  1236  (and any other retention structures and/or interlock features), the moldable material of the joining element  1232  may form a chemical or other adhesive bond with the material of the housing members  1220 ,  1225 . 
     The exterior surfaces of the joining element  1232  and the housing members  1220 ,  1225  may define a smooth continuous exterior surface  1223  of the housing. For example, any gaps, seams, or other discontinuities between the joining element  1232  and the housing members  1220 ,  1225  along the exterior surface  1223  of the housing may be undetectable to the touch and/or to the unaided eye. For example, a fingernail sliding along the exterior surface  1223  may not catch on the seam between the joining element  1232  and the housing members  1220 ,  1225 . In some cases, any gap, seam, or other discontinuity between the joining element  1232  and the housing members  1220 ,  1225  may be less than about 200 microns, less than about 100 microns, less than about 50 microns, less than about 20 microns, or less than about 10 microns (in depth, length, offset, and/or other dimension). The interlock between the joining element  1232  and the housing members  1220 ,  1225  may help prevent or inhibit relative motion between the housing members  1220 ,  1225  and the joining element  1232 , such as relative motion of these components along a vertical direction (as oriented in  FIG. 12D ). Accordingly, the protruding features  1230 ,  1236  may help maintain the substantially seamless texture and appearance between the joining element  1232  and the housing members  1220 ,  1225 . 
     In some cases, different types of structures may be used to reinforce or otherwise increase the strength and/or structural integrity of the coupling between housing members and joining elements.  FIG. 12E , for example, illustrates an example cross-sectional view of a housing that includes a joining element  1243  and a first housing member  1240  that defines a protruding feature  1244  (as shown in  FIGS. 12C-12D ) and a second housing member  1241  that defines a recess  1249  (as shown in  FIGS. 12A-12B ). Using a protruding feature  1244  and a recess  1249  may help increase the average or overall distance between the nearest portions of the first and second housing members  1240 ,  1241 . In particular, because one or both of the housing members  1240 ,  1241  may be used as a radiating component of an antenna system, it may be desirable to increase the distance between them to reduce capacitive coupling or other electromagnetic effects due to proximity of the two conductive components. By positioning a recess opposite a protrusion, the structural benefits of the protrusion (and the recess) may be achieved while also providing a greater distance between the closest surfaces of the housing members  1240 ,  1241  (as compared to a configuration with two protruding features, for example). 
       FIG. 12F  depicts a portion of an example device  1251 , showing another example configuration of housing components and a joining element that may be used to structurally couple the housing components. For example, a first housing member  1250  may be coupled to a second housing member  1252  via a joining element  1254 . Like other joining elements described herein, the joining element  1254  may be formed by injecting or otherwise introducing a moldable material (e.g., a polymer material) into a gap between the first and second housing members  1250 ,  1252 . The first housing member  1250  may define a first interlock feature  1253  that extends inwardly (e.g., towards an interior of the device) from a sidewall  1259  of the first housing member  1250 , and the second housing member  1252  may define a second interlock feature  1256  that extends inwardly (e.g., towards an interior of the device) from a sidewall  1257  of the second housing member  1252 . The first and second interlock features  1253 ,  1256  may be at least partially encapsulated by the joining element  1254 . For example, when a moldable material is injected or otherwise introduced into a gap between the first and second housing members  1250 ,  1252 , the moldable material may at least partially encapsulate the first and second interlock features  1253 ,  1256  (including flowing into any recesses or holes, and flowing around any protrusions defined by or on the first and second interlock features  1253 ,  1256 ). In some cases, the moldable material (e.g., which forms the joining element  1254 ) may cover the top surfaces of the first and second interlock features  1253 ,  1256 , such that the moldable material extends up to the interior surface of the sidewalls  1257 ,  1259 . 
     After the moldable material is cured or otherwise hardened to form the joining element, the joining element is physically interlocked to the first and second interlock features  1253 ,  1256 , thereby securing the first and second housing members  1250 ,  1252  together. 
     As shown in  FIG. 12F , the first housing member  1250  defines a first end surface  1266  and the second housing member  1252  defines a second end surface  1264 . The first and second end surfaces  1266 ,  1264  may be substantially parallel to one another, and may be substantially perpendicular to the exterior surfaces of the sidewalls  1257 ,  1259 . The first interlock feature  1253 , which extends inwardly from the sidewall  1259  (e.g., generally towards an interior of the device), may define a first angled surface  1260 . The angled surface  1260  may be angled generally away from the gap between the first and second housing members  1250 ,  1252 . The second interlock feature  1256  may define a second angled surface  1262 , which may extend generally towards the gap between the first and second housing members  1250 ,  1252 . Thus, the first and second angled surfaces  1260 ,  1262  may be nonparallel to the first and second end surfaces  1266 ,  1264 . Further, the first and second angled surfaces  1260 ,  1262  may be contiguous with the first and second end surfaces  1266 ,  1264 . The first and second end surfaces  1266 ,  1264  and the angled surfaces  1260 ,  1262  may define a channel between the first and second housing members  1250 ,  1252 , and the joining element  1254  may at least partially (and optionally completely) fill the channel defined by the first and second end surfaces  1266 ,  1264  and the angled surfaces  1260 ,  1262 . 
     The angled configurations of the first and second interlock features  1253 ,  1256  reposition structural components within the device to make room for other components. For example, by having the second interlock feature  1256  angle to the right (as shown in  FIG. 12F ), additional space may be provided on the left side of the second interlock feature  1256  for another component  1299  (e.g., a logic board, a processor, or the like). The other component  1299  may therefore be positioned closer to the sidewall  1257  (and further to the right) than would be possible if the second interlock feature  1256  extended perpendicularly from the housing member  1252 . 
     The first and second angled surfaces  1260 ,  1262  may also improve the strength, stiffness, or other structural property of the interlock between the first and second housing members  1250 ,  1252  by providing a more complex geometry with which the joining element ultimately engages and interlocks. Further, because the first and second angled surfaces  1260 ,  1262  extend at a similar (or identical) angle (relative to the end surfaces  1266 ,  1264 , for example), a greater distance may be maintained between the first and second housing members  1250 ,  1252  (as compared to angled surfaces that angled towards one another, or that had a greater difference in angle relative to the end surfaces). Stated another way, the substantially parallel angled surfaces  1260 ,  1262  may improve the strength and/or stability of the housing structure without reducing the minimum distance between the housing members. Because having the housing elements closer together may increase capacitive coupling between the housing members, and thus could negatively impact antenna performance, larger distances between the housing components may be advantageous. The angled surfaces of the interlock features therefore may achieve improved strength while maintaining adequate antenna performance. 
       FIG. 12G  depicts another portion of the example device  1251 , showing another example configuration of housing components and a joining element that may be used to structurally couple the housing components. For example, the first housing member  1250  may be coupled to a third housing member  1280  via a joining element  1270 . Like other joining elements described herein, the joining element  1270  may be formed by injecting or otherwise introducing a moldable material (e.g., a polymer material) into a gap between the first and third housing members  1250 ,  1280 . The first housing member  1250  may define a first interlock feature  1271  that extends inwardly (e.g., towards an interior of the device) from a sidewall  1259  of the first housing member  1250 , and the third housing member  1280  may define a second interlock feature  1272  that extends inwardly (e.g., towards an interior of the device) from a sidewall  1281  of the third housing member  1280 . The first and second interlock features  1271 ,  1272  may be at least partially encapsulated by the joining element  1270 . For example, when a moldable material is injected or otherwise introduced into a gap between the first and third housing members  1250 ,  1280 , the moldable material may at least partially encapsulate the first and second interlock features  1271 ,  1272  (including flowing into any recesses or holes, and flowing around any protrusions defined by or on the first and second interlock features  1271 ,  1272 ). In some cases, the moldable material (e.g., which forms the joining element  1270 ) may cover the top surfaces of the first and second interlock features  1271 ,  1272 , such that the moldable material extends up to the interior surface of the sidewalls  1259 ,  1281 . 
     Similar to the configuration shown in  FIG. 12F , the first housing member  1250  may define a first end surface  1278  and the third housing member  1280  may define a second end surface  1279 , with the end surfaces defining a gap between the first and third housing members. The first and second end surfaces  1278 ,  1279  may be substantially parallel to one another, and may be substantially perpendicular to the exterior surfaces of the sidewalls  1259 ,  1281 . The first interlock feature  1271 , which extends inwardly from the sidewall  1259  (e.g., generally towards an interior of the device), may define a first angled surface  1276 . The angled surface  1276  may be angled generally away from the gap between the first and third housing members  1250 ,  1280 . The second interlock feature  1272  may define a second angled surface  1277 , which may extend generally towards the gap between the first and third housing members  1250 ,  1280 . Thus, the first and second angled surfaces  1276 ,  1277  may be nonparallel to the first and second end surfaces  1278 ,  1279 . Further, the first and second angled surfaces  1276 ,  1277  may be contiguous with the first and second end surfaces  1278 ,  1279 . The first and second end surfaces  1278 ,  1279  and the angled surfaces  1276 ,  1277  may define a channel between the first and third housing members  1250 ,  1280 , and the joining element  1270  may at least partially (and optionally completely) fill the channel defined by the first and second end surfaces  1278 ,  1279  and the angled surfaces  1276 ,  1277 . 
     The first and second interlock features  1271 ,  1272  may also include lugs  1273 ,  1274 , which may remain exposed or otherwise accessible through the joining element  1270  even after the interlock features are at least partially encapsulated by the joining element  1270 . Electrical components, such as an antenna circuitry, may be conductively coupled to the housing members  1250 ,  1280  (which may be conductive), such that the housing members  1250 ,  1280  can operate as radiating members of an antenna system. 
     The angled configurations of the first and second interlock features  1271 ,  1272  reposition structural components within the device to make room for other components. For example, by having the second interlock feature  1272  angle upwards (as shown in  FIG. 12G ), additional space may be provided below the second interlock feature  1272  for another component (e.g., a camera module). For example,  FIG. 12G  shows an example frame member  1283 , to which camera modules may be attached. The upward angle of the second interlock feature  1272  provides space where a shoulder region of the frame member  1283  may be positioned. If the second interlock feature  1272  were to extend horizontally into the interior of the device (relative to the orientation shown in  FIG. 12G ), the frame member  1283  would have to be positioned lower in the device, which may lead to wasted space. Thus, by configuring the first and second interlock features  1271 ,  1272  with angled surfaces (and, more generally, protruding at a non-perpendicular angle from the sidewalls), other components may be able to be positioned in desired locations, and there may be more flexibility in where other components can be located within the housing. 
     As noted above, interlock features, such as the first and second interlock features  1271 ,  1272 , may be used to facilitate a conductive coupling between conductive housing members and antenna circuitry. For example, as described with respect to  FIG. 12G , antenna circuitry may be conductively coupled to the housing members  1250 ,  1280  via lugs  1273 ,  1274  (which may be or may include threaded holes).  FIG. 12H  illustrates a portion of the device  1251 , illustrating how antenna circuitry may be conductively coupled to the lugs  1273 ,  1274 , and in particular, how a flexible circuit element may be conductively coupled to the lugs  1273 ,  1274  despite the complex geometries and small available space in the corner of the device.  FIG. 12H  illustrates the housing of the device  1251  without the joining element in place. 
     As shown in  FIG. 12H , an antenna connection assembly  1290  may be used to conductively couple the housing members  1250 ,  1280  to antenna circuitry. The antenna connection assembly  1290  may include a flexible circuit element  1284 , and a connector assembly  1289 . The connector assembly  1289  may include conductors  1286 ,  1285  which are at least partially encapsulated in a polymer frame. For example, the conductors  1286 ,  1285  may be insert molded with the polymer material of the frame to form the connector assembly  1289 . The connector assembly  1289  may be structurally and conductively coupled to the first and second interlock features  1271 ,  1272  via conductive fasteners  1287 ,  1288  (e.g., screws, bolts, threaded fasteners, posts, rivets, welds, solders, etc.). The conductive fasteners  1287 ,  1288  may be conductively coupled to the conductors  1286 ,  1285 , which in turn are conductively coupled (e.g., soldered) to conductive traces of the flexible circuit element  1284 . The conductive traces of the flexible circuit element  1284  may also be conductively coupled to antenna circuitry of the device. Accordingly, a conductive path may be defined from the interlock features  1271 ,  1272 , through the conductors  1286 ,  1285  in the connector assembly  1289 , and through the flexible circuit element  1284 , to the antenna circuitry elsewhere in the device. The connector assembly  1289  may be configured so that a conductive coupling to the lugs  1273 ,  1274 , which are on top of the interlock features and are in a plane that is generally perpendicular to the sidewall of the device, can be made to the flexible circuit, which is generally flat and in a plane that is parallel to the sidewall of the device (and slotted into a narrow gap between the frame member  1283  and the housing member  1280 ). Without the connector assembly, interconnecting the flexible circuit element to the lugs may require bending the flexible circuit into a different plane, which may stress the flexible circuit and potentially damage it. Further, there may not be room in the device for the bend radiuses necessary to facilitate a bent or curved flexible circuit element. Accordingly, the connector assembly  1289  may facilitate the connection between components that lie in or along perpendicular planes (or otherwise face different directions). 
     The devices described herein include touch-sensitive displays, also referred to as touchscreen displays. In such cases, display components and touch sensor components may be layered or otherwise integrated to form an assembly that may be positioned below a transparent cover. In order to facilitate the display and touch-sensing functionality, electrical signals must be passed to and from the display and touch-sensing layers to other components such as processors and other circuitry (which may not be suitably sized and/or shaped to fit into the layered structure of the display stack). Accordingly, flexible circuit elements with flexible conductive traces or other conductors may be used to interconnect the layers of the display stack with processors and other circuitry.  FIGS. 13A and 13B  illustrate example configurations of flexible circuit elements for interconnecting to layers in the display stack.  FIG. 13C  illustrates an example integration of a display stack (which may include touch-sensor components) in a device. 
       FIG. 13A , for example, illustrates a cover  1300  (which may be an embodiment of the cover  102 ,  202 ,  302 ,  402 ,  502 , or any other cover described herein) and a display stack  1302 . The display stack  1302  may include display layers (e.g., LED layers, OLED layers, electrode layers, polarizers, etc.) and touch sensor layers (e.g., capacitive electrode layers, spacer layers, etc.). The display stack  1302  may define a recessed region  1304 , which may define an area where input/output devices are positioned so that they are not covered or otherwise interfered with by the display stack  1302 . 
     Because the display stack  1302  includes display layers and touch sensor layers that need to be interconnected with other circuitry, each set of layers includes a flexible circuit element that extends from a side of the display stack  1302 . In particular, the display layers may include or be coupled to a flexible circuit element  1306  that extends from a first side of the display stack  1302  (e.g., a short side), and the touch sensor layers may include a flexible circuit element  1308  that extends from a second side of the display stack  1302  (e.g., a long side). By having the two flexible circuit elements  1306 ,  1308  extend from different sides of the display stack  1302 , the overall size of the display stack  1302  may be reduced relative to having them extend from the same side. For example, if both flexible circuit elements extended from the same side (e.g., the short side), one may have to loop over the other, thus extending the size of the display stack  1302  along that side. Further, the flexible circuit elements may require physical distance from each other, requiring the outer loop to be set apart from the inner loop by an air gap or other space, which may further increase the size of the display stack  1302  along that side. 
     Whereas the display stack  1302  included touch sensor layers on a different substrate than the display layers (e.g., thereby requiring different flexible circuit elements in order to conductively couple to the different layers), the display stack  1312  of  FIG. 13B  may have an integrated (on-cell) touch-sensing system. For example, an array of electrodes that are integrated into an OLED display may be time and/or frequency multiplexed in order to provide both display and touch-sensing functionality. The electrodes may be configured to detect a location of a touch, a gesture input, multi-touch input, or other types of touch input along the external surface of the cover  1310 . Accordingly, instead of providing separate flexible circuit elements extending from different sides of the display stack, the display stack  1312  may include a shared flexible circuit element  1316 , which includes conductive traces for both display and touch-sensing functions (in some cases, some or all of the conductive traces may be used for both display and touch-sensing functions). 
       FIG. 13C  illustrates a partial cross-sectional view of a device  1320 . The device  1320  may include a housing member  1324 , a rear cover  1326 , and a cover  1322  coupled to a frame member  1328 . The device  1320 , housing member  1324 , cover  1322 , rear cover  1326 , and frame member  1328  may be embodiments of or otherwise correspond to other instances of those devices and components described herein. Details of those devices and/or components may be equally applicable to those shown in  FIG. 13C , and will not be repeated here for brevity. 
     The device  1320  includes a display stack  1330  coupled to the cover  1322  via an adhesive stack  1334 . The display stack  1330  may be attached to the cover  1322  prior to the cover  1322  being attached to the frame member  1328 . In some cases, the frame member  1328  may be bent or otherwise deflected during the assembly process so that a loop area  1352  of the display stack  1330  can pass the frame member  1328  (e.g., a flange portion such as the flange portion  629 ,  FIG. 6A ) without contacting the frame member  1328 . The frame member  1328  may be manually deflected by a tool, and allowed to return to an undeflected state after the cover  1322  is secured to the frame member  1328  via an adhesive, as described herein. The frame member  1328  may be configured so that the deflection of the frame member  1328  during assembly is less than the elastic limit of the frame member  1328 . The frame member  1328  may be metal (e.g., stainless steel, aluminum, or another suitable metal). The frame member  1328  may be a continuous, generally rectangular loop of metal that extends around the periphery of the display stack  1330 . In some cases, the continuous loop includes polymer members or sections that structurally couple to one or more metal members. For example, a frame member  1328  may include a metal member that defines a first portion of the substantially rectangular loop (e.g., at least a portion of each of three sides of the rectangle), and a polymer member that is structurally coupled to the ends of the metal member and defines the remaining portion of the substantially rectangular loop. 
     The display stack  1330  may include a display element  1333  for producing graphical outputs. In some cases, the display element  1333  may include components of an OLED display. For example, the display element  1333  may include a cathode layer, an electron transport layer, a blocking layer, an emissive layer, a hole transport layer, a hole injection layer, an anode, and a substrate. The display element  1333  may also include filters, polarizers, thin film transistors, or the like. The display element  1333  may be coupled to a flexible circuit element  1332  or other suitable substrate. While an OLED display is described, the display element may be any suitable type of display, such as an LCD display, an active layer organic light emitting diode (AMOLED) display, an organic electroluminescent (EL) display, an electrophoretic ink display, or the like. 
     The adhesive stack  1334  may be or may include an optically clear adhesive that adheres the display stack  1330  (or a component thereof) to the cover  1322 . The adhesive stack  1334  may be a single, substantially homogenous layer of adhesive, or it may include multiple layers and/or materials. For example, the adhesive stack  1334  may include a light-transmissive polymer layer positioned between two adhesive layers (e.g., a top adhesive layer adhering to the cover  1322  and a bottom adhesive layer adhering to the display stack  1330 ). In some cases, a multi-layer adhesive stack  1334  (e.g., with two adhesive layers on opposite sides of a polymer layer) may have an increased stiffness as compared to a single-layer adhesive stack of the same size. As such, a multi-layer adhesive stack  1334  may be made thinner than a single-layer adhesive stack while maintaining the same or similar stiffness as the single-layer adhesive stack. 
     The image quality of a display may be affected by the flatness of the display stack and/or the layers of a display element. For example, warped display layers may produce wavy patterns or other visible effects, which may reduce the functionality of the display (e.g., making it unable to effectively produce images or other graphical outputs). In order to provide a dimensionally stable structure and to help maintain flatness of display components, the display stack  1330  may include stiffening structures in the display stack. For example, the display stack  1330  may include a first stiffening structure  1336  which may include a metal layer (also referred to as a metal plate). The metal layer may support the display element  1333  and/or the flexible circuit element  1332  and impart structural support, rigidity, and flatness to the display element  1333  and/or the flexible circuit element  1332 . The first stiffening structure  1336  may have the same or substantially the same front-facing area as the display element  1333  (e.g., the first stiffening structure  1336  may have a front-facing area that is greater than 90% of the front-facing area of the display element  1333 ). The first stiffening structure  1336  may also include one or more additional layers, such as one or more foam layers, one or more adhesive layers, and/or one or more polymer layers. 
     The display stack  1330  may also include a second stiffening structure  1340 , which may include a metal layer (also referred to as a metal plate). The metal layer of the second stiffening structure  1340  may support the display element  1333  and/or the flexible circuit element  1332  and impart structural support, rigidity, and flatness to the display element  1333  and/or the flexible circuit element  1332 . The second stiffening structure  1340  may have a smaller frontal area than the first stiffening structure  1336 . For example, the second stiffening structure  1340  may be positioned only (or substantially only) in the area where the flexible circuit element  1332  is doubled over (e.g., overlapping area  1335 ). Both the overlapping area  1335  and the second stiffening structure  1340  may have a front-facing area that is less than 50% of the front-facing area of the display element  1333 , and optionally less than 30% of the front-facing area of the display element  1333 . 
     The display stack  1330  may include a compliant structure  1338  between the first and second stiffening structures  1336 ,  1340 . The compliant structure  1338  may be or may include a layer of foam, one or more adhesives, or the like. The compliant structure  1338  may be configured to absorb energy due to impacts, drop events, or the like, thereby reducing the likelihood of damage to components of the display stack  1330 . 
     The display stack  1330  may also include a third stiffening structure  1360 . The third stiffening structure may be positioned on the same side of the flexible circuit element  1332  as a processor  1350 , which may be a display integrated circuit that interfaces with another processor of the device  1320  and controls the display stack  1330  so as to produce graphical outputs via the display stack  1330 . The processor  1350  may also receive and/or process signals from touch-sensing components integrated with the display stack  1330  (such as electrodes that facilitate capacitive-based touch-sensing functions). In some cases, the processor  1350  may be a different type of circuit element, such as a memory module. The third stiffening structure  1360  may be or may include a metal layer (also referred to as a metal plate). The third stiffening structure  1360  may reinforce the area of the flexible circuit element  1332  around the processor  1350 , where small and potentially fragile electrical interconnects may be positioned. The third stiffening structure  1360  may help inhibit bending or other deformations in the area near the electrical interconnects and may therefore help prevent damage and improve reliability of the device. 
     The first, second, and third stiffening structures  1336 ,  1340 , and  1360  are described as including metal layers. The metal layers may be formed from stainless steel, aluminum, or the like. The metal layers may have a thickness of about 120 microns, about 100 microns, about 70 microns, or any other suitable dimension. In some cases the metal layers may have a thickness of between about 120 microns and about 60 microns, or between about 65 microns and about 95 microns. In some cases, the stiffening members may be formed from or include polymers, composites (e.g., carbon fiber), or other suitable materials. 
     The display stack  1330  may also include a shroud  1346  that covers the processor  1350 . The shroud  1346  may be or may be formed from or include metal or another suitable material (e.g., a polymer material, a composite material, etc.). The shroud  1346  may protect (and optionally shield) the processor  1350  from contacting other components inside the device  1320  in the event of a drop, impact, or other type of event that may cause the components of the device  1320  to shift, deflect, bend, or otherwise move relative to one another. Compliant members  1342  may be positioned between the shroud  1346  and the flexible circuit element  1332  and the processor  1350  and may be configured to absorb energy resulting from the device  1320  being dropped or otherwise subjected to an impact or other high-energy event. The compliant members  1342  may be attached to the shroud  1346  and the flexible circuit element  1332  and the processor  1350  via adhesives. 
     A potting material  1348  may be applied to the flexible circuit element  1332  and the processor  1350  along the periphery of the processor  1350 . The potting material  1348  may be an epoxy, adhesive, or another suitable material that may be applied to the flexible circuit element  1332  and the processor  1350  in a flowable state and then allowed to at least partially cure or harden. When cured, the potting material  1348  may contact and be bonded to both the flexible circuit element  1332  and at least a portion of a side (and optionally at least a portion of each of the peripheral sides) of the processor  1350 . In some cases, the potting material  1348  surrounds the outer periphery of the processor  1350   
     The potting material  1348  may help prevent the electrical interconnections (e.g., solder joints, wires, traces, or the like) between the flexible circuit element  1332  and the processor  1350  from breaking or becoming damaged during drops, impacts, or other potentially damaging events. The potting material  1348  may also locally increase the stiffness of the flexible circuit element  1332 , further helping to inhibit damage to the processor  1350  and/or the electrical interconnects. A cover  1344  (e.g., a metal foil, a polymer sheet, etc.) may at least partially cover the processor  1350  and the potting material  1348  and may provide an additional layer of protection to the processor  1350 . 
     As described above, a display element may include various electrically active layers and components that need to be electrically interconnected to other electrical components, processors, circuit elements, and the like. Because such layers (e.g., anode and cathode layers of an OLED display) may be sandwiched between other layers, the flexible circuit element  1332  (e.g., a flexible circuit board) may wrap around a side of the display stack  1330  at bend or loop area  1352  to electrically couple electrically active layers of the display element (e.g., TFT layers, electrode layers, etc.) and/or touch-sensing layers (such as one or more electrode layers that facilitate capacitive touch sensing, and which may be integrated with the display element  1333 ) to a processor  1350  of the display stack  1330 . More particularly, the flexible circuit element  1332  may include conductive traces that interconnect electrical components of the display layers (e.g., cathode and anode layers, electrode layers of touch and/or force sensors, on-cell touch-sensing layers, etc.) to other electrical traces, connectors, processors, or other electrical components that are mounted on the flexible circuit element  1332 . 
     In some cases, a potting material  1356  (e.g., an epoxy, foam, or other material or component) may be provided in the inside of the loop area  1352  to help provide structure to the flexible circuit element  1332  at the loop area  1352  and to help prevent deformation of the flexible circuit element  1332  due to drops, impacts, or the like. For example, if the device  1320  is dropped on the housing member  1324 , the housing member  1324  could force the frame member  1328  against the loop area  1352  of the flexible circuit element  1332 . The potting material  1356  may help prevent such impacts from breaking, pinching, bending, deforming, or otherwise damaging the flexible circuit element  1332  at the loop area  1352 . 
     The display stack  1330  may also include a strain reduction layer  1354 , which may be applied to the flexible circuit element  1332  along the outside of the loop area  1352 . The strain reduction layer  1354  may be an epoxy, adhesive, polymer, or other suitable material. The strain reduction layer  1354  may increase the stiffness of the flexible circuit element  1332  along the loop area  1352  and may maintain or form the flexible circuit element  1332  into a desired bend radius (e.g., a maximum possible bend radius given the length of the loop area  1352  and the geometry of the display stack  1330 ). The strain reduction layer  1354  may also help provide structure to the flexible circuit element  1332  at the loop area  1352  and help prevent deformation of the flexible circuit element  1332  due to drops, impacts, or the like. 
     The potting material  1356  may be applied to the display stack  1330  after the flexible circuit element  1332  is folded over to form the loop area  1352 . For example, a flowable material, such as a curable epoxy, may be injected into the loop area  1352  after the circuit element  1332  is folded over and the second stiffening structure  1340  is attached to the first stiffening structure  1336  (e.g., via a compliant structure and one or more adhesive layers). The flowable material may at least partially harden to provide the structural reinforcement described above. 
     In some cases, the potting material  1356  may be applied to the display stack  1330  prior to folding the flexible circuit element  1332 .  FIG. 13D  illustrates a portion of the device  1320  with the flexible circuit element  1332  in an unfolded configuration and with the potting material  1356  positioned on the flexible circuit element  1332  in a location that will define the loop area  1352  once the flexible circuit element  1332  is folded over into the configuration shown in  FIG. 13C . The potting material  1356  may be applied in a flowable state and the flexible circuit element  1332  may be folded over (e.g., along an axis) to define the loop area  1352  (e.g., as illustrated by arrow  1361 ) while the potting material  1356  is still in an at least partially flowable state. The potting material  1356  may then at least partially harden after the loop area  1352  is formed. As shown in  FIG. 13D , the strain reduction layer  1354  may be positioned on the flexible circuit element  1332  prior to the flexible circuit element  1332  being folded to form the loop area  1352 . 
       FIG. 14A  illustrates an example arrangement of cameras in a device  1400 .  FIG. 14A  may correspond to a corner of a device (e.g., the device  300 ), viewed with the cover and display (and optionally other components) removed to show the arrangement of the cameras. The device  1400  may include a first camera module  1402  (which may be an embodiment of or otherwise correspond to the first camera  361 ,  FIG. 3 ), a second camera module  1404  (which may be an embodiment of or otherwise correspond to the second camera  362 ,  FIG. 3 ), and a third camera module  1406  (which may be an embodiment of or otherwise correspond to the third camera  363 ,  FIG. 3 ). Any of the cameras shown in  FIG. 14A  (or elsewhere herein) may include an image stabilization system that helps maintain a sharp image (e.g., reducing the effects of camera shake on the image) by sensing movement of the device and moving one or more components of the camera in a manner that at least partially compensates for (and/or counteracts) the movement of the device. 
       FIG. 14A  also illustrates a depth sensor  1414  (which may be an embodiment of or otherwise correspond to the depth sensor  365 ,  FIG. 3 , or the depth sensor  565 ,  FIG. 5 ), and a microphone module  1412 . The microphone module  1412  may be positioned over or otherwise acoustically coupled to an opening in the housing of the device  1400  to allow sound to be captured by the microphone module  1412 . 
     The device  1400  may also include a bracket member  1410  (also referred to herein as a camera bracket) to which the first, second, and third camera modules  1402 ,  1404 ,  1406  may be coupled. The bracket member (or camera bracket)  1410  may define respective receptacles for each respective camera module. Each receptacle may define openings for the optical components of the camera modules. The receptacles may be defined by flanges or side walls that at least partially surround the camera modules. The bracket member  1410  may be configured to fix the relative positions of the camera modules. 
     The device  1400  may also include a frame member  1408  to which the bracket member  1410  and the depth sensor  1414  may be attached. The frame member  1408  may define a wall structure  1407 , which in turn defines a first container region  1411  and a second container region  1413 . As described herein, one or more cameras (which may be mounted to the bracket member  1410 ) may be positioned in the first container region, and the depth sensor module  1414  may be positioned in the second container region  1413 . The wall structure  1407  may define the second container region  1413  by extending completely around the second container region  1413 , or partially around the second container region  1413  (as shown). For example, the wall structure  1407  may define a wall segment  1439  that defines a free end. The free end may be set apart from other portions of the wall structure  1407  to define a gap or opening in the wall structure  1407 . 
     The frame member  1408  may be configured to fix the relative positions of the camera modules (which are in turn coupled to and held in alignment by the bracket member  1410 ) and the depth sensor module  1414 . The frame member  1408  may be configured to fix the relative positions of the camera modules and the depth sensor module  1414  in one or more directions. For example, the relative positions and/or orientations of the camera modules  1402 ,  1404 ,  1406  and the depth sensor module  1414  may be important to ensure proper operation of the features and/or functions of the camera modules  1402 ,  1404 ,  1406  and the depth sensor module  1414 . In some cases it is necessary or desirable for the optical axes of one or more of the camera modules  1402 ,  1404 ,  1406  and the depth sensor module  1414  to be parallel or to converge at a predetermined distance away from the device  1400 . As another example, it may be necessary or desirable for the offset between one or more of the camera modules  1402 ,  1404 ,  1406  and the depth sensor module  1414  (e.g., the offset along the optical axes) to be fixed at a predetermined distance. Such alignment and positioning may be necessary or desirable to provide functions such as camera focus assistance, depth mapping, image processing, or the like, and employing a common structure (such as the frame member  1408 ) to which both the depth sensor module  1414  and the camera modules  1402 ,  1404 ,  1406  (via the bracket member  1410 ) may be coupled may help establish and maintain the desired alignment and positioning. Notably, the frame member  1408  may establish and maintain any desired alignment, positioning, orientation, offset, or other spatial parameter, that results in the proper functioning of the optical systems. In some cases, the frame member  1408  is used to align the camera modules  1402 ,  1404 ,  1406  and the depth sensor module  1414  in the plane parallel to the interior surface  1436  of the rear cover  1432 , while out-of-plane alignment (e.g., in the up and down direction, as oriented in  FIGS. 14C-14D ) is provided by the interior surface  1436  of the rear cover  1432 . In some cases, the frame member  1408  is not used as an alignment datum or reference for the depth sensor module  1414 , such as when the depth sensor module  1414  is adhered or otherwise attached to the interior surface  1436  of the rear cover  1432  and the sides of the depth sensor module  1414  are not in intimate contact with the wall structure  1407  of the frame member  1408 . 
     In some cases, the frame member  1408  is not used as a datum for aligning the depth sensor module  1414 . For example, in some cases the frame member  1408  does not define a mounting surface (e.g., a surface parallel to or in contact with an interior surface of the rear cover  1432 ) in the container region where the depth sensor module  1414  is positioned. In such cases, the wall structure of the frame member  1408  may extend partially or completely around an open-bottomed container region in which the depth sensor module  1414  is positioned. Accordingly, in this configuration the depth sensor module  1414  is able to be coupled to the interior surface of the rear cover  1432 , such that the interior surface of the rear cover  1432  defines the datum surface for aligning and securing the depth sensor module  1414 . 
     The frame member  1408  may be coupled to other housing components or structures of the device  1400 , such as a rear cover (e.g., the rear cover  372 ,  FIG. 3 , the rear cover  572 ,  FIG. 5 , or any other suitable rear cover described herein). The frame member  1408  may be used as a datum or reference surface for the bracket member  1410  and/or the depth sensor module  1414 . 
       FIG. 14B  is a partial exploded view of the device  1400 , illustrating details of the frame member  1408 , the depth sensor module  1414 , the microphone module  1412 , and a housing  1422 . The housing  1422  may include a rear cover  1432 , which may be formed from glass, glass ceramic, ceramic, sapphire, or other suitable material. The rear cover  1432  may define a sensor array region  1433 , which may correspond to the size, shape, and location of the protrusion along the rear surface of the rear cover (e.g., the protrusions  137 ,  151 ,  FIGS. 1B, 1D ). 
     The rear cover  1432  may define or include camera windows  1424 ,  1426 ,  1428 ,  1430 , and  1409  in the sensor array region  1433 . The camera windows  1424 ,  1426 ,  1428 ,  1430 , and  1409  may be at least partially transparent (or may include or surround covers that are at least partially transparent) to allow the first, second, and third camera modules  1402 ,  1404 ,  1406 , the depth sensor module  1414 , and a flash suitable optical access through the rear cover  1432 . The camera windows  1424 ,  1426 ,  1428 ,  1430 , and  1409  may be unitary with the rear cover  1432  (e.g., transparent regions of the same piece of material as the rest of the rear cover  1432 ), or they may include or be defined by transparent covers, inserts, lenses, or other components or structures. In some cases, some of the windows are unitary with the rear cover  1432 , while others include or are defined by separate components or structures. 
     The rear cover  1432  may also define a microphone hole  1435  in the sensor array region  1433 . The microphone hole  1435  may extend through the rear cover  1432  to provide acoustic access to the external environment for the microphone module  1412 . In some cases, waterproof membranes and/or mesh materials (e.g., a screen) may be positioned in or otherwise cover the microphone hole  1435  to prevent ingress of liquids and/or other contaminants. 
     The frame member  1408  may be coupled to the rear cover  1432  along an internal surface of the rear cover and in the sensor array region  1433 . For example, the frame member  1408  may be attached to the internal surface of the rear cover  1432  via an adhesive  1420 . In some cases, as described herein, the frame member  1408  may be welded to camera trim structures that are coupled to the rear cover  1432 . The microphone module  1412  may also be attached to the rear cover  1432  via an adhesive  1421 . The depth sensor module  1414  may also be attached to the rear cover  1432  (e.g., the internal surface of the rear cover  1432 ) via an adhesive  1418 . In some cases, as described with respect to  FIGS. 14C-14D , the position of the depth sensor module  1414  in the device  1400  may be defined by the interface between the depth sensor module  1414  and the rear cover  1432 . The adhesives  1418 ,  1420 ,  1421  may be any suitable adhesive, such as a pressure sensitive adhesive (PSA), heat sensitive adhesive (HSA), adhesive film, epoxy, or the like. 
       FIG. 14C  is a partial cross-sectional view of the device  1400 , viewed along line  14 C- 14 C in  FIG. 14A , illustrating an example attachment and alignment configuration of the depth sensor module  1414  in the device  1400 . As shown in  FIG. 14C , the device  1400  includes a depth sensor module bracket  1446 . The depth sensor module  1414  may be attached to the depth sensor module bracket  1446  via an adhesive  1434  (e.g., a PSA, HSA, adhesive film, epoxy, or the like), and the depth sensor module bracket  1446  may be attached to an interior surface  1436  of the rear cover  1432  via the adhesive  1418 . 
       FIG. 14D  is a partial cross-sectional view of the device  1400 , viewed along line  14 C- 14 C in  FIG. 14A , illustrating another example attachment and alignment configuration of the depth sensor module  1414  in the device  1400 . In this example, the depth sensor module bracket  1446  may be omitted, and a surface of the housing of the depth sensor module  1414  itself may be attached to the interior surface  1436  of the rear cover  1432  via the adhesive  1418 . 
     Notably, in the configurations shown in  FIGS. 14C-14D , the position of the depth sensor module  1414  is fixed based on its attachment to the interior surface  1436  of the rear cover  1432 . Stated another way, the interior surface  1436  may act as a datum surface for positioning the depth sensor module  1414 . The interior surface  1436  may also ultimately act as a datum surface for the camera modules  1402 ,  1404 ,  1406 . Using a common datum surface for such optical components may help ensure accurate alignment and/or positioning of the optical components, which may improve or facilitate the operation of optical techniques such as depth-mapping or sensing, autofocus, or the like. In some cases, the depth sensor module  1414  does not contact and/or is not affixed to the frame member  1408 . In some cases, a foam or other compressible or compliant material may be positioned and/or compressed between portions of the depth sensor module  1414  and the frame member  1408 . 
     As described above, the depth sensor module  1414  may include an optical emitter  1448  and an optical sensor  1450 . The optical emitter may be adapted to emit one or more beams of light, which may be coherent light beams having a substantially uniform wavelength and/or frequency. In some cases, the light beam(s) may be laser beams. Using a coherent light source may facilitate depth measurements using a time of flight, phase shift, or other optical effect(s). The optical sensor  1450  may detect portions of the coherent light beams that are reflected by objects external to the device  1400 . Thus, for example, the optical emitter  1448  may project a pattern of dots onto the environment, and the optical sensor  1450  may capture an image of the environment. Using the reflections in the image of the pattern of dots, the device  1400  may calculate the distance between the device  1400  and objects in the environment. The device  1400  may then generate a depth map or rendering of the environment. The device  1400  may use the depth map or rendering for various purposes, such as for image processing, autofocus or other image capture features, augmented reality applications, measurements, or the like. The depth sensor module  1414  may be a lidar scanner. 
     Light may reach the optical emitter  1448  and the optical sensor  1450  through holes  1444  and  1442 , respectively, of the depth sensor module  1414 . In some cases, the device  1400  may include a mask  1440  positioned on the interior surface  1436  of the rear cover  1432 . The mask  1440  may be opaque and may define one or more openings. The openings in the mask  1440  may coincide with the optical path to and from the optical emitter and sensor  1448 ,  1450 . The mask  1440  may provide an optical shielding function for the depth sensor module  1414  (and other components in the device  1400 , such as the camera modules), and may occlude, cover, or otherwise limit visibility of other internal components of the device  1400  from the outside. The mask  1440  may be formed from any suitable material, such as an ink, dye, foil, film, coating (e.g., formed by plasma vapor deposition (PVD), chemical vapor deposition (CVD), or any other suitable coating process), or the like. 
       FIG. 14E  illustrates a top view of the bracket member  1410  with the camera modules removed. The bracket member  1410  may include a wall structure  1449  that defines three separate receptacles for three separate camera modules, and each receptacle may be defined by or include a bottom wall that defines a mounting surface to which a camera module may be attached, and a hole to allow the camera module to receive light. For example, the bracket member  1410 , and more particularly a wall portion of the wall structure  1449 , may extend around a least a portion of a periphery of a mounting surface  1425  with a first hole  1457  and define a first receptacle  1456  configured to receive a first camera module. Another wall portion of the wall structure  1449  may extend around at least a portion of a periphery of a mounting surface (e.g., ledges  1462 ) with a second hole  1459  and define a second receptacle  1458  configured to receive a second camera module. Another wall portion of the wall structure  1449  may extend around at least a portion of a periphery of a mounting surface  1427  with a third hole  1461  and define a third receptacle  1460  configured to receive a third camera module. The bottom wall of the second receptacle  1458  may define ledges  1462  on which the second camera module may be positioned and optionally adhered. The ledges  1462  may be positioned at the corners of the hole  1459 , and may also act as a datum surface to align and/or position the second camera module. The ledges may be used in place of a larger bottom wall (and correspondingly smaller hole) to help remove material from the bracket member  1410 , which may make the device lighter and reduce the overall thickness of the device. Camera modules may be positioned within the receptacles  1456 ,  1458 ,  1460  defined by the bracket member  1410 , and mounted to the mounting surfaces defined by the bracket member  1410  (e.g., the mounting surfaces  1425 ,  1427 , and ledges  1462 ). 
     The walls of the bracket member  1410 , including the bottom wall (e.g., the mounting surfaces of the bracket member  1410 ) and the wall structure that defines the side walls of the receptacles, may be used to align the camera modules to one another. For example, one or more of the side walls or the bottom wall of the receptacles may be used as a datum surface against which a camera module is positioned, adhered, fastened, secured, or otherwise interfaced. By interfacing all of the camera modules to the bracket member  1410 , which may be a structurally stable component such as a single piece of metal or another suitable material, all of the cameras can be aligned to a single, common structure, thereby improving the alignment and the overall durability and/or stability of the positioning. 
       FIG. 14F  is a partial cross-sectional view of the device, viewed along line  14 F- 14 F in  FIG. 14B , illustrating aspects of a camera trim structure  1473  and its integration with a rear cover of the device  1400  and a frame member (e.g., the frame member  1408 ). The camera trim structure  1473  may be a circular or other shaped structure that is positioned in an opening in a rear cover  1472  (and optionally secured to the rear cover  1472 ) and may define a raised border structure on the exterior of the device. The camera trim structure  1473  may be configured to receive and/or support a camera cover  1469 , which may be a piece of glass, sapphire, crystal, polymer, or any other suitable transparent or light transmissive material for covering a lens of a camera. A portion of a camera module (e.g., a camera lens) may extend into the camera trim structure  1473 . The camera trim structure  1473  may include an inner ring structure  1463  and an outer ring structure  1471 , which may be secured to one another via adhesive, threads, fusion bonds (e.g., welding, brazing, soldering), or any other suitable technique. The inner and/or outer ring structures  1463 ,  1471  may be formed of metal (e.g., steel, aluminum, stainless steel, or the like). 
     A frame member (in this case, the frame member  1408 ) may be positioned over at least a portion of the camera trim structure  1473 . The frame member  1408  may help secure the camera trim structure  1473  to the rear cover  1472 , and may define a mounting surface to which other components may be attached. The frame member  1408  may be secured to the inner ring structure  1463  via a weld plate  1465 , which may resemble a flat washer. The weld plate  1465  may be welded (or otherwise fusion bonded) to the frame member  1408  and to the inner ring structure  1463 . In some cases, the weld plate  1465  may be omitted (and the frame member  1408  may be fusion bonded directly to the inner and/or outer ring structures), or it may be welded to the outer ring structure  1471  instead of or in addition to the inner ring structure  1463 . 
     During the process of fusion bonding (e.g., welding) the weld plate  1465  to the frame member  1408  and the camera trim structure  1473 , molten metal or other contaminants may be ejected downwards, towards the camera trim structure  1473 . Accordingly, a conical washer  1466  (which may be or may be similar to a Belleville washer) may be positioned between and in contact with the frame member  1408  and the camera trim structure  1473 . The conical washer  1466  may contact the frame member  1408  at interface  1468  and contact the inner ring structure  1463  at interface  1468 . The conical washer  1466  may be subjected to sufficient force by the frame member  1408  and interface  1468  that a biasing force is present at the interfaces  1467 ,  1468 , thereby establishing a seal or at least maintaining positive contact at the interfaces. In this way, the conical washer  1466  may form a seal between the area that is being welded and the rear cover  1472 , thereby blocking molten metal or other contaminants that may be ejected during the fusion bonding process from contacting the rear cover  1472  or other components of the device. 
       FIG. 14G  illustrates a portion of the device  1400  with the bracket member  1410  removed, showing the frame member  1408  attached to a housing or enclosure. The frame member  1408  may define holes that coincide with camera windows  1424 ,  1426 ,  1428  (which may include or be defined by camera covers, as described herein). The frame member  1408  may be fusion bonded to the trim structures around the camera covers. The fusion bonds may be formed by a blue light laser (e.g., using light having a wavelength of around 450 nm), or by other suitable laser welding or other fusion bonding processes. By using a blue light laser, spatter may be reduced or eliminated as compared to other types of welding processes (e.g., arc welding, laser welding using lasers other than blue light lasers, etc.). Reducing or eliminating spatter may help prevent or inhibit molten metal or other contaminants from contacting the rear cover  1472  or other components of the device  1400 . Laser welding with a blue light laser may be used in addition to or instead of a conical washer as described with respect to  FIG. 14F . 
     The frame member  1408  may be fusion bonded to the trim structures by one or more beads (e.g., weld beads) around all or part of a perimeter of the camera windows. For example, as shown in  FIG. 14G , two beads  1475  may each extend around a portion (in this case, less than half) of the perimeter of the camera window  1428 , and two beads  1476  each extend around a portion (less than half) of the perimeter of the camera window  1424 . In some cases, more discrete beads may be used around a camera window, such as three, four, five, or more beads, each separated from adjacent beads by a gap.  FIG. 14G  also shows a bead  1477  that extends around an entire perimeter of the camera window  1426 . In some cases, a single bead that extends around less than the full perimeter may also be used. In a given device, different types of weld beads may be used around different camera windows (e.g., a first camera window may have a single full perimeter bead while another may have multiple partial-perimeter beads), or the same type of bead may be used around all of the camera windows. 
       FIG. 14H  is a partial cross-sectional view of a device that includes two rear-facing cameras, such as the device  200  in  FIG. 2 , viewed along line  14 H- 14 H in  FIG. 2 , for example. The cameras of mobile phones may be relatively delicate components due to the precision optics and sensors that they use. Accordingly, protecting them from extreme forces due to drops or other types of potentially damaging events may help prevent them from damage and generally improve the durability of the cameras. 
       FIG. 14H  shows how multiple different compliant members, each with different properties, may be positioned between camera modules and their mounting structures to help insulate the camera modules from potentially damaging forces or motions. For example, camera modules  1489 ,  1490  may be coupled to a bracket member  1481  (which may be similar to the bracket member  1410 , but configured for only two camera modules), and the bracket member  1481  may be coupled to a frame member  1491  (which may be similar to the frame member  1408 , but configured for two camera modules). The frame member  1491  may be coupled to trim structures  1483  and  1484  (e.g., via fusion bonds, as described above), and may be attached to a rear cover  1482  (e.g., a glass member) via an adhesive. Camera covers  1486 ,  1485  may be coupled to the trim structures or otherwise configured to cover the holes through which the camera modules receive light. 
     A multi-layer compliant structure may be positioned between (and in contact with) the bracket member  1481  and the frame member  1491  (or otherwise between the camera modules and a housing component or structure). The multi-layer compliant structure may include a first compliant member  1487  having first physical properties, and a second compliant member  1488  having second physical properties. The difference in physical properties between the first and second compliant members  1487 ,  1488  may help isolate the camera modules from different types of forces and/or motions. The first and second compliant members  1487 ,  1488  may differ in stiffness, compliance, Young&#39;s modulus, density, thickness, cell type (e.g., open cell, closed cell), or the like. For example, the first compliant member  1487  may have a lower stiffness (e.g., a lower Young&#39;s modulus) than the second compliant member  1488 . The first compliant member  1487  may be a polypropylene foam, and the second compliant member  1488  may be a polyurethane foam. The second compliant member  1488  may be adhered (or otherwise attached) to the bracket member  1481  and the first compliant member  1487  may be adhered (or otherwise attached) to the second compliant member  1488  prior to the bracket member  1481  being assembled with the frame member  1491 . Curable liquid adhesives, adhesive tapes or films, or other types of adhesives may be used to adhere the first compliant member  1487  to the frame member  1491 , to adhere the first compliant member to the second compliant member  1488 , and/or to adhere the second compliant member  1488  to the bracket member  1481 . 
     The relatively lower stiffness of the first compliant member  1487  may also form an environmental seal (e.g., air and/or water tight) against the frame member  1487 . The bracket member  1481  may be secured to the device such that the first and second compliant members  1487 ,  1488  are maintained in a compressed state. While  FIG. 14H  shows a particular structural configuration that includes both a bracket member  1481  and a frame member  1491 , the multi-layer compliant structure may be used with other types of structural configurations as well, such as configurations that omit the bracket member  1481  (or part of the bracket member  1481 ), and mount a camera module to the frame member  1491  or another housing member or structure (and thus position the multi-layer compliant structure between the camera module and the frame member  1491  or the other housing member or structure). 
     As the number of cameras integrated with a device increase, the overall complexity and number of electrical interconnections that must be made between the cameras and other circuitry in the device.  FIG. 14I  illustrates how the multiple camera modules may share a common connector by conductively coupling flexible circuit elements from two different camera modules. For example, the first camera module  1402  may include (or be coupled to) a first flexible circuit element  1492  that includes a connector  1493 . Conductive traces in the first flexible circuit element  1492  conductively couple components of the first camera module  1402  to the connector  1493  (and therefore to other components of the device). The third camera module  1406  may also include (or be coupled to) a second flexible circuit element  1495 . The second flexible circuit element  1495  may lack a connector, and instead may be conductively coupled to an interconnect area  1494  of the first flexible circuit element  1495 . Conductive traces in the first flexible circuit element  1492  may then conductively couple the connector  1493  to the traces in the second flexible circuit element  1495  and, ultimately, conductively couple electrical components of the second camera module to other components of the device (e.g., processors, circuitry, memory, power, etc.). As shown in  FIG. 14I , the second camera module  1404  may include (or be coupled to) a third flexible circuit element  1496  that includes its own connector. 
       FIG. 14J  shows the interconnect area  1494  of the first flexible circuit element  1492 , and a corresponding interconnect area of the second flexible circuit element  1495 . The first flexible circuit element  1492  includes a plurality of first solder pads  1498 , and the second flexible circuit element  1495  includes a plurality of second solder pads  1499  that are configured to be soldered to corresponding ones of the first solder pads  1498 . The first and second solder pads may be arranged in any suitable pattern, such as a grid pattern (as shown). The first and second solder pads may have different sizes to accommodate slight misalignments between the interconnect areas when the camera modules are assembled together. More particularly, as noted above, the alignment of the camera modules within the overall system and relative to one another may be important for providing a target performance level of the cameras and/or other optical functionalities. Accordingly, the solder pads, and the interconnect areas more generally, may be configured so that the conductive connections can be formed despite misalignments of the interconnect areas (which may result during the physical alignment processes for the camera modules). This may include configuring one of the groups of solder pads to have a larger size than the other. For example, as shown, the second solder pads  1499  are larger than the first solder pads  1498 . Accordingly, even if the first and second solder pads do not line up perfectly with one another (e.g., so each first solder pad is centered over the corresponding second solder pad), a positive conductive coupling is still formed. Further, the larger solder pads (the second solder pads  1499  in this case) may include a plurality of vias  1497 - 1 ,  1497 - 2 ,  1497 - 3 , which are configured to draw in or otherwise accept excess solder that may be present during the soldering of the first and second solder pads together. The multiple vias  1497  on each second solder pad  1499  may aid in the misalignment tolerance of the solder pads (as compared to solder pads with single vias, for example), because the solder connection between the solder pads will always be proximate to at least one of the multiple vias, even to the extent that the solder pads are not perfectly centered with respect to one another. 
     While  FIGS. 14A-14J  illustrate example devices that include three camera modules, this is merely one example implementation, and similar structures, features, techniques, and concepts may be applied to devices with other numbers of camera modules as well (e.g., one, two, four, five, or more camera modules). As one example, a device with two rear-facing cameras (e.g., the devices  100 ,  200 ,  400 ) may include a bracket member similar to the bracket member  1410 , but with only two receptacles (e.g., one receptacle for each rear-facing camera module). As another example, a frame member similar to the frame member  1408  (in  FIG. 14G ) but with only two holes for cameras may be welded to the device in the same manner shown and described with respect to  FIG. 14G . Similar adaptations may be made to other structures or architectures. 
       FIG. 15A  illustrates an example camera  1500  with an image stabilization system. The camera  1500  may correspond to the second camera  1404  in  FIG. 14  (which may, for example, have a 12 megapixel image sensor and a super-wide angle lens (120° FOV) with an aperture number of f/2.4). 
     The camera  1500  includes a lens assembly  1502 . The lens assembly  1502  may include one or more lens elements in a lens housing. The lens element(s) may define a lens with a 120° FOV and an aperture number of f/2.4. The lens housing may define a first retention feature  1504  configured to engage with a complementary feature of another component of the camera to retain the lens assembly with the camera  1500 . For example, the camera  1500  may include a first housing member  1506  that defines an opening  1508  that receives the lens assembly  1502 . The first housing member  1506  may further define a second retention feature  1510  that is configured to engage the first retention feature  1504  to retain the lens assembly  1502  to the first housing member  1506 . The camera  1500  may further include a second housing member  1528  that attaches to the first housing member  1506 . The first and second housing members  1506 ,  1528  may define an interior volume for holding components of the camera, and together they may at least partially enclose those components. The camera  1500  may also include a sensor (e.g., a 12 megapixel image sensor) on a circuit board  1512 . 
     As noted above, the camera  1500  may provide image stabilization functionality. Image stabilization may be performed along multiple axes. The camera  1500 , for example, provides image stabilization along three axes. For example, image stabilization along an axis  1501  may be provided by a first actuation system within the lens assembly  1502 . The first actuation system may include, for example, motors, actuators, and/or other components. When a movement of the device that has a component along the first axis  1501  is detected, the camera  1500  may cause one or more lens elements to move along the first axis  1501 . This movement may be configured to at least partially compensate for the movement of the device to attempt to maintain a sharp, in-focus image. 
     Image stabilization along second and third axes  1520 ,  1522  may be provided by a second actuation system that moves the sensor  1514  relative to the lens assembly  1502 . Motion of the sensor may be provided by the second actuation system, which may use electromagnetic actuators to produce the motion. The second actuation system may include electromagnetic coils, magnets, armature coils, and/or other suitable components. In some cases, the elements  1518 - 1 ,  1518 - 2 ,  1518 - 3 , and  1518 - 4  may be armature elements, which may each include an armature coil (and optionally a ferritic or other material core about which the armature coil may be wound) that is configured to be selectively energized to produce a force that will move the circuit board  1512  (which is one example of an image sensor carrier on which the image sensor may be attached) along one or both axes  1520 ,  1522 . In other cases the elements  1518 - 1 ,  1518 - 2 ,  1518 - 3 , and  1518 - 4  may be magnets, and a coil (e.g., a coil mounted to a flexible connector  1524 , the housing member  1506 , the second housing member  1528 , or another structure) may cause the elements  1518 - 1 ,  1518 - 2 ,  1518 - 3 , and  1518 - 4  to move the circuit board  1512  along one or both axes  1520 ,  1522 . 
     In order to provide image stabilization functionality using the moving circuit board system, when a movement of the device that has a component along the second axis  1520  and/or the third axis  1522  is detected, the camera  1500  may cause the circuit board  1512  to move along the first axis  1520  and/or the second axis  1522  in a manner that at least partially compensates for the movement of the device. By moving the lens assembly along the first axis  1501  and the circuit board  1512  (and sensor  1514 ) along the second and third axes  1520 ,  1522 , three-axis image stabilization may be provided by the camera  1500 . In some cases, image stabilization functionality may be provided by moving the lens assembly  1502  along two or three (or more) axes (instead of the one shown in  FIG. 15A ), and by moving the circuit board  1512  (and sensor  1514 ) along three (or more or fewer) axes. 
     In order to allow the circuit board  1512  to move relative to structural components of the camera  1500  (e.g., the housing member  1506  and the second housing member  1528 ) while also allowing electrical interconnection from the circuit board  1512  to other components of a device (e.g., processors, memory, power circuitry, etc.), the camera  1500  may include a flexible connector  1524  that conductively couples to the circuit board  1512  via conductive pads (e.g., solder pads) on an inner segment  1525 , and to other components of the device (e.g., a processor, memory, power circuitry, etc.) via conductive pads on a connector portion  1529  of an outer segment  1532 . The inner segment  1525  may be conductively yet flexibly coupled to the outer segment  1532  via flexible support members  1527 . The flexible support members  1527  may be formed by cutting slits or otherwise removing material from the flexible connector  1524  to form a plurality of strips that connect to the inner and outer segments  1525 ,  1532 . The strips of the flexible support members  1527  may include conductive traces (e.g., metal, indium tin oxide, etc.) to conductively couple the inner and outer segments  1525 ,  1532 . 
     The flexible support members  1527  may be conductively and physically coupled to the outer segment  1532  at outer connection regions  1530 , and to the inner segment  1525  at inner connection regions  1531 . The inner connection regions  1531  may be positioned on opposite sides of the flexible connector  1524 , and the outer connection regions  1530  may also be positioned on opposite sides of the flexible connector  1524  (and on adjacent sides relative to the inner connection regions  1531 . Accordingly, each flexible support member may extend around a corner of the flexible connector  1524 , thereby providing a suitable length of the flexible connector material to allow the inner segment  1525  to move relative to the outer segment  1532  while maintaining conductive coupling therebetween. 
       FIG. 15B  is a partial cross-sectional view of the flexible connector  1524 , viewed along line  15 B- 15 B in  FIG. 15A . The flexible connector  1524  may be formed of multiple layers. For example, a base layer  1533  may be a metal layer (e.g., formed from or comprising a metal such as a copper titanium alloy) having a thickness of between about 100 and about 140 microns. A base dielectric layer  1534  (e.g., a polyimide layer) having a thickness of between about 8 and about 12 microns may be positioned on the base layer  1533 . A conductive layer  1535  (e.g., copper traces having a thickness between about 10 and about 40 microns), which may include the conductive pads and the conductive traces that extend along the strips of the flexible support members  1527 , may be positioned on the base dielectric layer  1534 . A cover layer  1536  (e.g., a covercoat having a thickness of between about 3 and about 8 microns) may be positioned on the conductive layer  1535 . While the dielectric layer  1534 , conductive layer  1535 , and cover layer  1536  are labelled only on the outer segment  1532 , the same layers may be present on the inner segment  1525  and flexible support members  1527 , as shown in  FIG. 15B . 
     In some cases, the flexible connector  1524  may be formed by applying and/or depositing the dielectric layer  1534 , conductive layer  1535 , and cover layer  1536  on a sheet of material (e.g., the base layer material). The material may lack the slots  1537  (also referred to as gaps) between the flexible support members  1527  and the inner and outer segments  1525 ,  1532 , and may resemble a continuous sheet or layer (as indicated by the dotted horizontal lines in  FIG. 15B ). The base layer material may then be etched or cut to form the slots  1537 , thereby defining the distinct flexible support members  1527  and the inner and outer segments  1525 ,  1532 . The base layer  1533  may be etched or cut using any suitable process, including laser etching or cutting, plasma etching or cutting, machining, chemical etching, or the like. 
     As noted above, the devices described herein may include a flash that is configured to illuminate a scene to facilitate capturing images with one or more cameras of the electronic device. The flash, also referred to as a flash module, may include one or more light emitting diodes (LEDs) that produce the light to illuminate the scene. The flash module may be part of or positioned proximate a sensor array to facilitate illumination of scenes for flash photography. 
       FIG. 16A  illustrates a back view of a flash module  1600  (e.g., the side of the flash module that faces the interior of the device) that may be used with the devices described herein. For example, the flash module may be aligned with a flash window  1409  ( FIGS. 14A, 14B ). The flash module  1600  may include a carrier  1601  and a circuit board  1602 . The circuit board  1602  may be attached to the carrier  1601 , and the carrier  1601  may be secured to the device (e.g., in an opening or proximate a window in a rear cover of the device). 
     The circuit board  1602  may include electrical contact pads  1604  and  1606  arranged in a generally circular arrangement. For example, the circuit board  1602  may include a set of first contact pads  1604  arranged in a first generally circular arrangement (e.g., along a circle having a first diameter), and a set of second contact pads  1606  arranged in a second generally circular arrangement (e.g., along a circle having a second diameter that is larger than the first diameter) and around the set of first contact pads  1604 . The set of first contact pads  1604  and/or the set of second contact pads  1606  may be spaced evenly about their respective circles (e.g., having a same distance between any two adjacent contact pads). 
     The set of first contact pads  1604  may be used to conductively couple the LEDs (and/or other circuitry, processors, or other electrical components) of the flash module  1600  to other circuitry and/or components of a device. Thus, wires, traces, leads, or other conductive elements may be soldered, welded, or otherwise conductively coupled to the set of first contact pads  1604 . The set of second contact pads  1606  may also be conductively coupled to the LEDs (and/or other circuitry, processors, or other electrical components) of the flash module  1600 , and may be provided to facilitate testing of the flash module without having to make physical contact with the set of first contact pads  1604 , thereby avoiding potential damage or contamination of the set of first contact pads  1604 . 
       FIG. 16B  is a partial cross-sectional view of the flash module  1600 , viewed along line  16 B- 16 B in  FIG. 16A , showing an example integration of the circuit board  1602  with the carrier  1601 . The carrier  1601  may be a single unitary piece of light transmissive material, such as glass, a light-transmissive polymer, sapphire, or the like. 
     The carrier  1601  may define a ledge  1614 , which may define a recess in which the circuit board  1602  is positioned. For example, the ledge  1614  may be recessed relative to a back surface  1612  of the carrier  1601 . The ledge  1614  may be recessed from the back surface  1612  a distance that is substantially equal to the thickness of the circuit board  1602  or is otherwise configured based on a dimension of the circuit board  1602  such that the back of the circuit board  1602  is flush with or recessed relative to the back surface  1612  of the carrier  1601 . The circuit board  1602  may be attached to the carrier  1601  via an adhesive (e.g., between the ledge  1614  and the circuit board  1602 ). 
     In some cases, a coating  1661 , such as an ink, mask, dye, paint, film, a vapor deposition coating (e.g., chemical or plasma vapor deposition), or the like, may be applied to the back surface  1612 . In some cases, the coating  1661  is an opaque white coating. In other cases, the coating  1661  is a mirror-like reflective coating (e.g., a silver PVD or CVD coating). The coating  1661  may prevent or limit the visibility of internal components of a device through the material of the carrier  1601 , and may help avoid the presence of a black or dark ring-like appearance around the perimeter of the flash module  1600  (e.g., when the external-facing surface of the flash module  1600  is viewed when the flash module  1600  is integrated with a device). 
       FIG. 16B  also shows light emitting elements  1608  and  1610  (e.g., LEDs) attached to the circuit board  1602  and configured to emit light downward, towards a lens portion  1616  of the carrier  1601 . The lens portion  1616  may be or define a Fresnel lens (or other type of lens) that focuses, diffuses, or otherwise changes the light to produce a desired spread or illumination angle. The lens portion  1616  may be integrally formed into the carrier  1601  (e.g., the material of the carrier  1601  may define the lens portion  1616 ). In some cases, the lens portion  1616  may be a separate element that is attached to the carrier  1601 . 
     The carrier  1601  may also define a recess  1618  in a sidewall to receive a compliant member  1620 . The compliant member  1620  may be an o-ring (or other suitable compliant member) and may be configured to form an environmental seal between the carrier  1601  and part of the housing of the device in which it is integrated (e.g., the surfaces of a hole or recess in a rear cover of a device). 
       FIG. 16C  is a partial cross-sectional view of a flash module  1630 , showing a view similar to that of  FIG. 16B . The flash module  1630  includes a differently configured carrier  1631  and compliant member  1634 . In particular, the carrier  1631  may define a shaped recess  1632  in a sidewall, and the shaped recess  1632  is configured to receive a shaped compliant member  1634 . The shaped compliant member  1634  may be molded in place in the recess  1632 . For example, a flowable material, such as a polymer material, may be introduced into the shaped recess  1632  and allowed to at least partially cure to form the compliant member  1634 . An external mold or other tool may surround the carrier  1631  during the polymer introduction and/or injection process to form the shape of the exterior surfaces of the compliant member  1634 . 
     The shaped compliant member  1634  (and the shaped recess  1632 ) may extend further into the sidewall of the carrier  1631  than the compliant member  1620  and the recess  1618  in  FIG. 16B . This configuration may allow the compliant member  1634 , which may be opaque, to occlude or otherwise block the appearance of the internal components of the flash module  1630  and the internal components of a device more generally. For example, the shaped compliant member  1634  extends into the sidewall of the carrier  1631  such that there is a distance  1636  between the end of the shaped compliant member  1634  and the outer perimeter of the lens portion  1633  of the carrier  1631 . By contrast, as shown in  FIG. 16B , the compliant member  1620  may extend a shorter distance into the sidewall, resulting in a distance  1622  (which is greater than the distance  1636 ), thereby potentially allowing more visibility into the internals of the flash module and the device. The greater depth of the shaped recess  1632  and the increased size and the contoured shape of the compliant member  1634  may also result in a more dimensionally stable compliant member  1634  that can stay in a desired position through greater forces and deflections, as compared to an o-ring for example. 
     As with the carrier  1601 , the carrier  1631  may be a single unitary piece of light transmissive material, such as glass, a light-transmissive polymer, sapphire, or the like. The flash module  1630  may also include the circuit board  1602  and the light emitting elements  1608  and  1610  (e.g., LEDs), and the circuit board  1602  may be attached to the carrier  1631  in the same or similar manner as the flash module  1630 . 
     Flash modules may be manufactured by an assembly process in which the circuit boards are singulated from a base sheet and then attached to an adhesive sheet in an array for further assembly.  FIG. 16D  illustrates portions of the assembly process for the flash modules described herein. At state  1640 , individual circuit boards  1652  for flash modules may be fabricated on a substrate  1650 . The substrate  1650  may be a circuit board (e.g., a mother sheet), and the circuit boards  1652  may include traces, contact pads, and/or other conductive elements to facilitate electrical interconnection of the flash module&#39;s components. 
     At state  1642 , electrical components of the flash module have been applied to the circuit boards  1652 . The electrical components may be applied using surface mount technology (SMT) assembly processes, or any other suitable process. The electrical components may include, for example, processors, LEDs, integrated circuits, and/or other electrical components of the flash module. 
     At state  1644 , the individual circuit boards  1652  are singulated from the substrate  1650  (e.g., with a cutter  1656 , which may be a knife, laser, or the like) so that they can be applied to a temporary adhesive substrate  1654 , as shown at state  1646 . While on the temporary adhesive substrate  1654  (e.g., a silicone tape), carriers  1658  are attached to the circuit board  1652  (e.g., via an adhesive, as described above). State  1648  shows a completed flash module  1660  (which includes a circuit board, carrier, LEDs, and other components of a flash module) being removed from the temporary adhesive substrate  1654 . The completed flash module  1660  may be subjected to further processing (e.g., applying mask layers, adhesives, etc.) and then assembled into a device such as a mobile phone. 
     By applying singulated circuit boards to the temporary adhesive substrate  1654  (e.g., in an array or grid pattern) as described in  FIG. 16D , the process of attaching the carriers to the circuit boards may be performed using pick-and-place machinery, SMT machinery, and/or other automated machinery and assembly processes that may be faster and/or more efficient than other types of assembly processes (e.g., attaching carriers to singulated circuit boards that are free from one another). 
     The display in a device such as a mobile phone provides a large degree of the functionality of the device, but can also present challenges. For example, unwanted light leaks from the display may produce distracting and unattractive visual phenomenon. Accordingly, devices may include features and configurations to reduce or eliminate light leaks and/or the appearance of light leaks. 
       FIG. 17A  illustrates a partial cross-sectional view of a device  1700 , which may be an embodiment of the device  600  or any other device described herein. Details of those devices may be equally applicable to the device  1700 , and will not be repeated here for brevity. The device  1700  includes a cover  1702  and a housing member  1704 , which may be embodiments of other covers and housing members described herein, and details of those components will not be repeated here for brevity. As noted above, some light that is emitted from a display during normal use of the display may propagate through the cover  1702  and exit the cover from a side, edge, or corner of the cover  1702 . For example,  FIG. 17A  illustrates example light rays  1706  (which may ultimately originate from a display) that propagate towards the perimeter of the cover  1702  and ultimately exit from the cover  1702  to produce a light leak  1708 . The light that exits the cover  1702  may exit the cover  1702  at various angles, such that a portion of the light  1706  reflects off of the housing member  1704  while another portion does not. Whereas the light rays  1706  are shown incident on a top or outer edge, light rays  1703 , which may come from the display, may be incident on an inner or bottom edge  1705  of the cover  1702 . The light rays  1703  may be reflected off of the edge  1705  (or otherwise illuminate the edge  1705 ) and may be visible through the cover  1702 . 
     The portions of the housing members that are near the light leak areas (e.g., edges of the cover, which extend around the perimeter of the cover) may have shapes, textures, coatings, and/or other treatments or features that are configured to reduce or eliminate the amount and/or appearance of light leaks from a device. For example,  FIGS. 17B-17G  illustrate various examples of such configurations. 
       FIG. 17B , which may correspond generally to the area  17 B- 17 B in  FIG. 17A , illustrates an example housing member  1710  (which may be an embodiment of the housing member  1704  or any other housing member described herein) and the cover  1702 . A corner region  1712  of the housing member  1710  may define a cover-facing surface  1714  that is substantially vertical (relative to the orientation shown in  FIG. 17B ), and/or is substantially perpendicular to a front exterior surface  1701  (also referred to as a top surface) of the cover  1702 . As used herein, a cover-facing surface may refer to a surface of a housing member on which light that exits from a side or edge of the cover is incident or otherwise reflects off of. 
     A coating may be applied to all or some of the cover-facing surface  1714  to absorb, diffuse, or deflect light, or otherwise reduce the amount or visibility of light that is leaked from the cover  1702  onto the housing member  1704 . For example, one or more layers of ink, dye, film, paint, deposited material (e.g., PVD or CVD layer), or other material may be adhered to, bonded to, formed on, or otherwise applied to all or some of the cover-facing surface  1714 . As one specific example, a black coating on the cover-facing surface  1714  may absorb at least a portion of incident light from the cover  1702 . In some cases, a coating may also or instead be applied to the edge  1705  (which may be a chamfered edge). The coating may include a black, opaque ink (one or more layers), which may be positioned on the bottom (or interior) surface of the cover  1702 , the chamfered edge  1705 , and a side surface (e.g., between the top and bottom chamfered edges of the cover  1702 ). Additional details of the coating on the cover  1702  are described with respect to  FIGS. 17H-17I . 
     In some cases, instead of or in addition to a coating on the cover-facing surface  1714 , the cover-facing surface  1714  may have a surface texture that is configured to absorb, diffusely reflect, or otherwise reduce the visibility of light leaked from the cover  1702 . For example, the cover-facing surface  1714  may have a surface texture with a root mean square (RMS) height from about 0.1 microns to about 2.5 microns, from about 0.25 microns to about 2 microns, or from about 0.5 microns to about 2 microns. The surface texture may differ from the surface texture of other portions of the housing member, which may be smoother (e.g., have a lower RMS height, average roughness, or other surface parameter) than the textured portion of the cover-facing surface  1714 . The surface texture may be formed in various ways, such as via machining, abrasive blasting, chemical etching, laser etching, or the like. 
     Other types of surface treatments may also be used. For example, a laser may be used to change the appearance of the cover-facing surface  1714 , such as by darkening the surface, changing a color of the surface, or the like. Other types of treatments that may be used include anodizing, plating (e.g., electroplating), grinding, machining, abrasive blasting, oxidizing, or the like. 
       FIG. 17C , which may correspond generally to the area  17 B- 17 B in  FIG. 17A , illustrates an example housing member  1720  (which may be an embodiment of the housing member  1704  or any other housing member described herein) and the cover  1702 . A corner region  1722  of the housing member  1720  may define a chamfer surface  1724  (which may be considered a cover-facing surface). For example, the chamfer surface  1724  may be non-perpendicular and non-parallel to a front exterior surface  1701  of the cover  1702 . The chamfer surface  1724  may extend at an internal angle of about 135 degrees, relative to a cover-facing surface  1726  (which may be substantially perpendicular to the front exterior surface  1701  of the cover  1702 ), or at another suitable angle (e.g., as shown in  FIGS. 17E and 17F ). The angle of the chamfer surface  1724  may result in a more diffuse reflection or otherwise produce a less noticeable appearance of light leaked from the cover  1702 . One or both of the chamfer surface  1724  and the cover-facing surface  1726  may include a coating, texture, and/or be subjected to other surface treatments, as described above with respect to  FIG. 17B . In some cases, the surfaces may have different combinations of coating, texture, and/or surface treatments (e.g., one surface may have a different combination of coatings, textures, and/or surface treatments than another surface). In some cases, a coating may also or instead by applied to the edge  1705 , as described herein. 
       FIG. 17D , which may correspond generally to the area  17 B- 17 B in  FIG. 17A , illustrates an example housing member  1730  (which may be an embodiment of the housing member  1704  or any other housing member described herein) and the cover  1702 . A corner region  1732  of the housing member  1730  may define a curved surface  1734  (which may be considered a cover-facing surface). For example, the curved surface  1734  may have a partially cylindrical shape, or have any other curved shape (e.g., a spline). In some implementations, the curved surface  1734  has a radius of curvature between about 5 microns and about 100 microns, between about 5 microns and about 75 microns, or between about 5 microns and about 50 microns. The curvature and/or shape of the curved surface  1734  may reduce the presence and/or appearance of light leaked from the cover  1702  and incident on the curved surface  1734 . For example, a curved surface  1734  with a radius of curvature of about 100 microns or less (or about 50 microns or less) limits the surface area that could reflect light that is leaked from the cover  1702 . 
     One or both of the curved surface  1734  and a cover-facing surface  1736  (which may be substantially perpendicular to the front exterior surface  1701  of the cover  1702 ) may include a coating, texture, and/or be subjected to other surface treatments, as described above with respect to  FIG. 17B . In some cases, the surfaces may have different combinations of coating, texture, and/or surface treatments (e.g., one surface may have a different combination of coatings, textures, and/or surface treatments than another surface). In some cases, a coating may also or instead by applied to the edge  1705 , as described herein. 
     While  FIG. 17C  illustrates a chamfer surface with an internal angle of about 135 degrees (e.g., a 45 degree chamfer), other angles may also be used. For example,  FIG. 17E , which may correspond generally to the area  17 B- 17 B in  FIG. 17A , illustrates an example housing member  1740  (which may be an embodiment of the housing member  1704  or any other housing member described herein) and the cover  1702 . A corner region  1742  of the housing member  1740  may define a chamfer surface  1744  (which may be considered a cover-facing surface). The chamfer surface  1744  may be non-perpendicular and non-parallel to a front exterior surface  1701  of the cover  1702 . The chamfer surface  1744  may extend at a different angle from a cover-facing surface  1746  (which may be substantially perpendicular to the front exterior surface  1701  of the cover  1702 ) as compared to the chamfer surface  1724  in  FIG. 17C . For example, the internal angle between the chamfer surface  1744  and the cover-facing surface  1746  may be between about 135 degrees and about 90 degrees. The angle of the chamfer surface  1744  may result in a more diffuse reflection or otherwise produce a less noticeable appearance of light leaked from the cover  1702 . One or both of the chamfer surface  1744  and the cover-facing surface  1746  may include a coating, texture, and/or be subjected to other surface treatments, as described above with respect to  FIG. 17B . In some cases, the surfaces may have different combinations of coating, texture, and/or surface treatments (e.g., one surface may have a different combination of coatings, textures, and/or surface treatments than another surface). In some cases, a coating may also or instead by applied to the edge  1705 , as described herein. 
       FIG. 17F , which may correspond generally to the area  17 B- 17 B in  FIG. 17A , illustrates an example housing member  1750  (which may be an embodiment of the housing member  1704  or any other housing member described herein) and the cover  1702 . A corner region  1752  of the housing member  1750  may define a chamfer surface  1754  (which may be considered a cover-facing surface). The chamfer surface  1754  may be non-perpendicular and non-parallel to a front exterior surface  1701  of the cover  1702 . The chamfer surface  1754  may extend at a different angle from a cover-facing surface  1756  (which may be substantially perpendicular to the front exterior surface  1701  of the cover  1702 ) as compared to the chamfer surface  1724  in  FIG. 17C . For example, the internal angle between the chamfer surface  1754  and the cover-facing surface  1756  may be between about 135 degrees and about 180 degrees. The angle of the chamfer surface  1754  may result in a more diffuse reflection or otherwise produce a less noticeable appearance of light leaked from the cover  1702 . One or both of the chamfer surface  1754  and the cover-facing surface  1756  may include a coating, texture, and/or be subjected to other surface treatments, as described above with respect to  FIG. 17B . In some cases, the surfaces may have different combinations of coating, texture, and/or surface treatments (e.g., one surface may have a different combination of coatings, textures, and/or surface treatments than another surface). In some cases, a coating may also or instead be applied to the edge  1705 , as described herein. 
       FIG. 17G , which may correspond generally to the area  17 B- 17 B in  FIG. 17A , illustrates an example housing member  1760  (which may be an embodiment of the housing member  1704  or any other housing member described herein) and the cover  1702 . A corner region  1762  of the housing member  1760  may define a chamfer surface  1764  (which may be considered a cover-facing surface). The chamfer surface  1764  may be non-perpendicular and non-parallel to a front exterior surface  1701  of the cover  1702 . The chamfer surface  1764  may extend at any suitable angle (e.g., with an internal angle between about 90 degrees and about 180 degrees) from a cover-facing surface  1766  (which may be substantially perpendicular to the front exterior surface  1701  of the cover  1702 ). The housing member  1760  may also define an undercut region  1768 . The undercut region  1768  may be below the corner region  1762  (e.g., further towards the interior of the device as compared to the corner region  1762 ), and may include an additional chamfer surface  1767  (which may have any suitable angle). The undercut region  1768  may help absorb, reflect, and/or deflect light that exits the cover  1702  from a side surface  1769  of the cover  1702 . For example, the undercut region  1768  may reflect leaked light inwardly (e.g., generally towards the interior of the device), thereby reducing the amount and/or intensity of leaked light that is visible to the user. One or more of the chamfer surface  1764 , the additional chamfer surface  1767 , and a cover-facing surface  1766  may include a coating, texture, and/or be subjected to other surface treatments, as described above with respect to  FIG. 17B . In some cases, the surfaces may have different combinations of coating, texture, and/or surface treatments (e.g., one surface may have a different combination of coatings, textures, and/or surface treatments than another surface). In some cases, a coating may also or instead by applied to the edge  1705 , as described herein. 
       FIG. 17H  illustrates a partial cross-sectional view of the cover  1702 , illustrating an example configuration for the edges of the cover  1702  and a coating to prevent light leaks through the cover  1702 . The cover  1702  may define a front surface  1701 , which may also be referred to as a top surface of the cover  1702 , that defines a portion of the exterior front surface of a device. The cover  1702  may also define a bottom surface  1773  that is opposite the front surface  1701 . The cover  1702  may also define a peripheral side surface  1774 . The cover  1702  may also define a first chamfered edge  1705  extending from the bottom surface  1773  to the peripheral side surface  1774 , and a second chamfered edge  1775  extending from the top surface  1701  to the peripheral side surface  1774 . 
     A coating  1770 , such as an opaque coating, may be positioned on a portion of the bottom surface  1773 , the first chamfered edge  1705 , and at least a portion of the peripheral side surface  1774  (and optionally all of the peripheral side surface). The coating  1770  may be configured to absorb light emitted by the display stack and incident on the chamfered edge  1705  (and/or the apexes where the chamfered edge  1705  meets the peripheral side surface  1774  and the bottom surface  1773 ). The coating  1770  may include a layer of ink, such as an opaque, black ink, having an average thickness of about 5 microns. The coating  1770  may have a minimum thickness between about 1.5 microns and about 10 microns. In some cases, the coating  1770  includes multiple layers of ink. The coating  1770  may also include films, sheets, dyes, deposited coatings (e.g., plasma vapor deposition, chemical vapor deposition), or the like. 
     A cover layer  1771  may cover at least a portion of the coating  1770  along the bottom surface  1773 , chamfered edge  1705 , and peripheral side surface  1774 . The cover layer  1771  may protect the coating  1770  from damage or wear during handling, assembly, and manufacturing. The cover layer  1771  may be a transparent coating, an opaque coating, or the like. The cover layer  1771  may be an acrylic resin, an epoxy, a film, a sheet, or any other suitable material. The cover layer  1771  may have a higher ductility than the coating  1770 , and as such may be more resistant to damage than the coating  1770  itself. 
       FIG. 17I  illustrates a partial cross-sectional view of a cover  1780 , which is similar to the cover  1702  in  FIG. 17H  but includes rounded chamfered edges  1784 ,  1785 . The cover  1780  also defines a front surface  1783 , which may also be referred to as a top surface of the cover  1780 , that defines a portion of the exterior front surface of a device. The cover  1780  may also define a bottom surface  1781  that is opposite the front surface  1783 . The cover  1780  may also define a peripheral side surface  1782 . A coating  1786  may be positioned on a portion of the bottom surface  1781 , a portion of the peripheral side surface  1782 , and the rounded chamfered edge  1784 , and a cover layer  1787  may be positioned on the coating  1786 . The coating  1786  and the cover layer  1787  may be embodiments of the coating  1770  and the cover layer  1771 , and the details of the coating  1770  and the cover layer  1771  will not be repeated here for brevity. 
     The rounded chamfers  1784  and  1785  may have a non-circular shape. For example, the rounded chamfers  1784  and  1785  may be defined by a spline defined by a varying (e.g., non-constant) radii of curvature. In some cases, the rounded chamfers  1784  and  1785  are mirror images of one another and are formed simultaneously (e.g., by a grinding operation). 
     Devices as described herein may include speakers to produce audio output that may be perceived by a user. Such audio output may include, for example, music, notifications (e.g., ringtones, incoming message notification sounds, etc.), voice communications, audio content of videos, etc. Because speakers need to be acoustically and/or fluidly coupled to the external environment, the physical interface between an internal speaker module and the external environment may require adequate sealing in order to prevent ingress of water, sweat, dust, and/or other contaminants into the device. Further, speaker modules may need to be replaced and/or repaired periodically, and as such it may be advantageous to physically integrate speaker modules into the device in a manner that facilitates access and removal operations. 
     As noted above, devices such as the mobile phones described herein may include haptic actuators that produce haptic outputs. A haptic actuator may include a movable mass and an actuation system that is configured to move the mass to produce the haptic output. The moveable mass must therefore have enough mass (relative to the device in which it is integrated) and must move enough distance to produce a suitably noticeable haptic output (e.g., one that a user can physically detect, optionally while in a pocket or in a purse). These operational constraints thus limit the extent to which the size of the actuator can be reduced, as it may not be feasible or preferable to have a movable mass that is less than a certain threshold mass or to reduce the distance that the mass is able to move. However, space inside modern electronic devices, such as smartphones, is at a premium. Accordingly, techniques for reducing the size of a haptic actuator without reducing its effectiveness may be particularly useful in reducing the overall sizes of devices and/or for fitting more features or components into devices of the same size. 
       FIG. 18  illustrates an example arrangement of components in a device  1800 .  FIG. 18  may correspond to a corner of a device (e.g., the device  300 ), viewed with the cover and display removed to show the arrangement of various example internal components. The device  1800  may include a housing  1802  at least partially defining an interior volume. The device  1800  may also include a haptic actuator  1804 , a battery  1808 , a speaker module  1810 , a first component  1812 , a second component  1814 , a third component  1816 , a fourth component  1818 , and a fifth component  1820 . The first through fifth components may be any suitable electrical and/or structural components, systems, circuit elements (e.g., circuit boards), or the like. For example, the first component  1812  may be a circuit board or part of a circuit board that includes circuitry for a charging port of the device  1800  (and/or other suitable components). The second component  1814  may be a circuit board or part of a circuit board that includes a pressure sensor and a microphone (and/or other suitable components). In some cases, the second component  1814  may also include a water-resistant air-permeable membrane that is positioned over an opening in the housing  1802  to allow air to pass into and out of the device  1800 , while preventing water and other liquids or contaminants into the device  1800 . 
     The third component  1816  may be a circuit board or part of a circuit board that includes communications components, such as antennas, processors, memory, analog-to-digital converters, filters, amplifiers, power control circuitry, or the like. In some cases, the communications components may be configured to facilitate WiFi communications (or other communication protocols). 
     The fourth component  1818  may be a circuit board or part of a circuit board, or another component. In some cases, the fourth component  1818  is a shield, cowling, board-to-board connector, a structural component (e.g., a mounting member or flange, an alignment spring), or the like. 
     The fifth component  1820  may be a portion of a logic board. The logic board may include a substrate, and processors, memory, and other circuit elements coupled to the substrate. Where the fifth component  1820  is a logic board, it may include multiple circuit substrates that are stacked and coupled together. The fifth component  1820  may include provisions for a subscriber identity module (SIM). The fifth component  1820  may include electrical contacts and/or a SIM tray assembly for receiving a physical SIM card and/or the fifth component  1820  may include provisions for an electronic SIM. 
     In order to reduce the amount of space required for the haptic actuator  1804  while also maintaining its effectiveness in producing haptic outputs, the haptic actuator  1804  may include an outer housing with a non-rectangular shape. For example, instead of a rectangular shape (as shown by the dotted box  1806 ), the haptic actuator  1804  may include a peripheral side member with protruding portions  1823  and recessed portions  1822 . The protruding portions of the peripheral side member define recessed regions  1824 , which may be occupied by other components of the device  1800 . For example, as shown, the recessed regions  1824  allow components such as the battery  1808 , the second component  1814 , and the third component  1816  to be larger and/or positioned more compactly arranged than would be possible if the haptic actuator  1804  had a parallelogram shape (as illustrated by the box  1806 ). As described with respect to  FIG. 19A , the protruding portions  1823  may provide a space for springs of the haptic actuator to extend into, thus allowing the recessed portions  1822  to be positioned closer to the movable mass, thereby reducing the amount of empty space within the haptic actuator  1804 . 
       FIG. 19A  illustrates a portion of a haptic actuator  1900 , which may be or may be an embodiment of the haptic actuator  1804  in  FIG. 18 . The haptic actuator  1900  is shown without a top member or cover to reveal internal components of the haptic actuator  1900 . 
     The haptic actuator  1900  includes a housing  1902  (of which a peripheral side member is shown), which may be formed of metal, polymer, or any other suitable material. The haptic actuator also includes a movable mass  1908 . The movable mass  1908  may include one or more magnets  1910  coupled thereto. The magnets  1910  may produce a magnetic field, and the haptic actuator  1900  may also include coils (e.g., coupled to the top member or cover of the haptic actuator  1900 ). The coils and the magnets  1910  may interact with one another to produce a force on the movable mass  1908  to cause the movable mass to move (e.g., along a left-right direction, as oriented in  FIG. 19A ) to produce a haptic output. In some cases, the haptic actuator  1900  is a Lorentz force actuator. 
     The haptic actuator  1900  also includes springs  1906 . The springs  1906  may be formed from metal, a polymer, or another suitably compliant material. The springs  1906  may provide a return force to the movable mass  1908  during actuation (e.g., left-right movement) of the movable mass  1908 . Due to the physical attachment between the movable mass  1908  and the housing  1902 , the springs  1906  may impart the force or impulse of the movable mass  1908  to the housing  1902 , which in turn results in the force or impulse being imparted to the device more generally to produce the desired haptic output. 
     The springs  1906  may also physically maintain the movable mass  1908  in a central or rest position when the movable mass  1908  is not being moved to produce a haptic output. The springs  1906  may provide structural support in the direction into and out of the page (e.g., the z-direction), such that the movable mass  1908  does not rest or slide against top and bottom members or covers of the haptic actuator  1900 . The springs  1906  may be secured to the housing  1902  and to the movable mass  1908 . For example, the first ends of the springs  1906  may be secured to first locations  1911  on an interior of the housing  1902 , and the second ends of the springs  1906  may be secured to second locations  1913  on the movable mass  1908 . 
     The performance of the springs  1906 , including parameters such as spring constant, cycle limit, or the like, may depend at least in part on the size and shape of the springs  1906 . In some cases, for example, shortening the springs along the height direction  1915 , for example, may change the spring rate or reduce the cycle limit of the springs  1906 . Accordingly, simply shortening the springs  1906  to allow the housing  1902  to be reduced in size may result in unsatisfactory operation and/or lifespan of the haptic actuator  1900 . In order to reduce the footprint of the haptic actuator  1900  while providing for springs that are longer in the height direction  1915 , the housing  1902  includes outwardly protruding features  1904 . The protruding features  1904  define internal areas or recesses  1917  into which a portion of the springs  1906  extend. As shown, bend portions  1903  of the springs  1906  extend into the recesses  1917 , though other spring designs may have other portions of the springs extending into the recesses  1917 . As described above with respect to  FIG. 18 , by including the protruding features  1904  in the peripheral side member of the housing  1902 , another portion of the peripheral side member may define recessed portions  1905  of the housing  1902 . Stated another way, the protruding portions  1904  and recessed portions  1905  may generally conform to or follow the contour of the outer perimeter of the internal components of the haptic actuator  1900 . A distance between the inner surface of the recessed portions of the peripheral side member of the housing  1902  and the movable mass  1908  may be less than about 1.0 mm, less than about 0.8 mm, less than about 0.5 mm, or less than about 0.3 mm. 
     The recessed portions  1905  result in a haptic actuator that occupies less space than one in which a housing is formed as a rectangle (or otherwise does not have the protruding and recessed portions). For example, lines  1909  show an example location of the peripheral side member of a housing that lacks the protruding and recessed portions of the haptic actuator  1900 . In that case, the housing would enclose empty space that could otherwise be used for other components of the device (e.g., allowing increased battery size or the like). 
       FIG. 19B  illustrates another example haptic actuator  1920  that minimizes or reduces the amount of empty space enclosed by the peripheral side member of the actuator housing. The haptic actuator  1920  includes a housing  1922 , which may be formed of metal, polymer, or any other suitable material. The haptic actuator also includes a movable mass  1928  which may include magnets  1930 . The movable mass  1928  and magnets  1930  may be the same as or similar to the movable mass  1908  and magnets  1910  of  FIG. 19A , and the details of these components will not be repeated here for brevity. The haptic actuator  1920  also includes springs  1926 . The springs  1926  may be formed from metal, a polymer, or another suitably compliant material. The springs  1926  may be the same as or similar to the springs  1906  of  FIG. 19A , and the details of these components will not be repeated here for brevity. 
     Whereas the housing  1902  in  FIG. 19A  defines protruding portions (and associated recessed portions) to provide space for the springs while also reducing the amount of unused space inside the actuator, the housing  1922  in  FIG. 19B  defines openings  1924  to accommodate the bend portions  1923  of the springs  1926 . In particular, the portions of the springs  1926  that extend past the movable mass  1928  extend through the openings  1924 . This allows the peripheral side member  1927  to conform to the shape of the movable mass  1928 . A distance between the inner surface of the peripheral side member  1927  and the movable mass  1928  may be less than about 1.0 mm, less than about 0.8 mm, less than about 0.5 mm, or less than about 0.3 mm. 
     Covers may be attached to the housing  1922  over the openings  1924 . The covers may enclose or seal the housing  1922 , for example, to prevent ingress of contaminants into the haptic actuator  1920 . The covers may be flexible components, such as flexible films, fabrics, polymers, or the like, and may be configured to conform to and/or contact the bend portions  1923  of the springs. 
       FIG. 20A  is a partial cross-sectional view of a device  2003 , which may be an embodiment of the device  700  in  FIG. 7 . Accordingly,  FIG. 20A  illustrates the device  2003  viewed along a line analogous to line  20 - 20  in  FIG. 7 . The device  2003  includes a housing member  2000 , which may be an embodiment of the housing member  705  in  FIG. 7 . The housing member  2000  may be coupled to a rear cover  2010  via an adhesive  2016 , as described herein. The housing member  2000  may define a speaker hole  2002  (which may correspond to or be analogous to the speaker holes  751 ,  FIG. 7 ) that extends through the housing member  2000 . The speaker hole  2002  may be fluidly coupled to a speaker module  2001  to allow sound (e.g., propagating pressure waves in air) from the speaker module  2001  to exit the device. The speaker module  2001  may correspond to or be an embodiment of a speaker module  752 ,  FIG. 7 ). The housing member  2000  may define a plurality of speaker holes (as shown in  FIG. 7 ), or a single speaker hole. A speaker hole cover  2004  may be positioned in, may cover, or may otherwise shield the speaker hole  2002 . The speaker hole cover  2004  may inhibit ingress of water, dust, and/or other debris or contaminants, while still allowing sound to exit the device  2003  through the speaker hole  2002 . The speaker hole cover  2004  may include a mesh screen, a semi-permeable membrane, and/or other suitable components. The speaker hole cover  2004  (and/or the device  2003  more generally) may also include springs, brackets, clips, and/or other features or components to secure the speaker hole cover  2004  to the housing member  2000 . 
     The device  2003  may include a speaker module bracket  2012  (also referred to simply as a bracket  2012 ) coupled to the housing member  2000 . The bracket  2012  may be coupled to the housing member  2000  via an adhesive  2014  (e.g., a PSA, HSA, adhesive film, epoxy, or the like). The bracket  2012  may define a protruding portion  2028  that extends at least partially into the speaker hole  2002  to facilitate a rigid and secure coupling between the bracket  2012  and the housing member  2000 . 
     The device  2003  may also include a speaker module  2001  that is coupled to the device housing and produces sound. The speaker module  2001  may include a speaker driver  2099  that produces the sound. The speaker module  2001  may be secured to the housing via screws, bolts, clips, adhesives, and/or other fasteners. 
     The speaker driver  2099  may be configured to output sound in a direction transverse to the main plane of the device  2003  (e.g., towards the front or rear covers, or upward or downward in the orientation shown in  FIG. 20A ). The direction of sound output may also be described as being parallel to a side exterior surface defined by the housing member  2000 . The sound waves may be redirected through a channel and towards the speaker hole  2002  along the path  2006 . For example, the housing member  2000  may define a first channel portion  2098 , the bracket  2012  may define a second channel portion  2097 , and the speaker module  2001  may define a third channel portion  2096  and a fourth channel portion  2095 . The first channel portion  2098  may extend along a first direction that is oblique (e.g., not parallel to and not perpendicular to) the exterior side surface defined by the housing member  2000 . The second channel portion  2097  may extend along substantially the same direction as the first channel portion  2098 . The third channel portion  2096  may extend along a second direction that is different from the first direction, and the fourth channel portion  2095  may extend along a third direction that is different from the first and second directions. The serpentine-like path  2006  that is defined by the various channel portions may facilitate the porting of sound from the speaker driver  2099  (which may be perpendicular to the front cover of the device) to the speaker hole  2002 , which is positioned at a middle of a side surface of the housing member  2000  (which is perpendicular to the front cover of the device). 
     The device  2003  may also include a sealing assembly  2018  that contacts the speaker module  2001  and a sealing interface surface  2026  of the bracket  2012  to produce a seal between the speaker module  2001  and the bracket  2012 . This may perform several functions. For example, the seal provided by the sealing assembly  2018  may produce an acoustic seal along the sound path  2006  (e.g., the channel or chamber through which sound passes when travelling from the speaker module  2001  to the speaker hole  2002 ). The acoustic seal may prevent or limit air from escaping the sound path  2006  and entering the interior of the device, as such escaping air may negatively impact the efficiency, acoustic quality, or other property of the speaker module  2001 . The seal provided by the sealing assembly  2018  may also help inhibit any liquid, debris, or other contaminant that may reach the sound path  2006  from escaping into other internal areas of the device  2003 . 
     The sealing assembly  2018  may include a carrier  2022 , a first compliant portion  2020 , and a second compliant portion  2024 . The carrier  2022  may be a stiff material or combination of materials (relative to the compliant portions  2020 ,  2024 , for example). For example, the carrier  2022  may be formed from a polycarbonate material, a metal sheet, or the like. The first and second compliant portions  2020 ,  2024  may be formed from or include a foam, elastomer, rubber, or other material that can conform to and/or seal against the sealing surface  2026  and a surface of the speaker module  2001 . The first and second compliant portions  2020 ,  2024  may be co-molded with the carrier  2022  to secure the compliant portions  2020 ,  2024  to the carrier  2022  and produce a single assembly that can be attached to or otherwise assembled with the device  2003 . The first and second compliant portions  2020 ,  2024  may also or instead be secured to the carrier  2022  with adhesives or other fastening components. The compliant portions  2020 ,  2024  may be a monolithic structure (e.g., they may be different portions of a single compliant material structure), or they may be separate components (e.g., two separate pieces of compliant material each attached to the carrier  2022 ). 
     The sealing assembly  2018  may be attached to the speaker module  2001  (e.g., via adhesive, mechanical fasteners, etc.), or it may be held in place by force (e.g., by being compressed between the speaker module  2001  and the bracket  2012 ). In either configuration, the sealing assembly  2018  may be forced into contact with the speaker module  2001  and the sealing surface  2026  in order to at least partially deform the material of the compliant portions  2020 ,  2024  and conform them to the speaker module  2001  and the sealing surface  2026 . More particularly, when the speaker module  2001  is fastened to the device  2003  and fixed in position, the distance between the speaker module  2001  and the sealing surface  2026  may be smaller than the associated dimension of the sealing assembly  2018 . Accordingly, the sealing assembly  2018  is ultimately compressed between the sealing surface  2026  and the speaker module  2001 , thereby forming the desired seal between the components. 
     As noted above, the speaker module  2001  may be removable from the device  2003  to facilitate repair and/or replacement operations. Further, the speaker module  2001  may be assembled by positioning the speaker module  2001  in place in the device housing and securing the speaker module  2001  to the device  2003 . It may therefore be advantageous to configure the speaker module  2001  and the device  2003  more generally so that the speaker module  2001  may be installed and/or removed simply and without interfering with other components. Accordingly, the speaker module  2001  and the bracket  2012  are configured so that the speaker module  2001  can be removed by lifting the speaker module  2001  vertically out of the device  2003 , and without requiring significant horizontal movement. In particular, the sealing surface  2026  of the bracket  2012  and a bracket interface portion  2030  of the speaker module  2001  (see  FIG. 20B ) are angled such that the speaker module  2001  may be attached and/or detached from the device  2003  using a vertical movement of the speaker module  2001 . For example, the sealing surface  2026  may define a plane that is non-parallel and non-perpendicular to a plane defined by the exterior surface of the rear cover  2010 . In some cases the plane defined by the sealing surface  2026  may be angled at about 45 degrees relative to the exterior surface of the rear cover  2010 . The oblique angle of the sealing surface  2026  (and thus of the interface between the sealing surface  2026  and the bracket interface portion  2030  of the speaker module  2001 ) may facilitate vertical installation and removal operations, while also providing a relatively unobstructed sound path  2006 . By contrast, if the angle were perpendicular to the exterior surface of the rear cover, installation and removal of the speaker module may require a horizontal movement component (or a greater horizontal movement component), making installation and removal of the speaker module  2001  more difficult and inconvenient, and if the angle were parallel to the exterior surface of the rear cover, the sound path  2006  may require sharper corners, angles, and/or turns, which may negatively impact acoustic performance. 
     The angled interface, as well as the configuration of the sound path  2006 , as shown in  FIG. 20B  may be selected so that the speaker hole  2002  is positioned at a central position (vertically) in the housing member  2000 . By positioning the speaker hole  2002  in or near the vertical middle of the housing member  2000 , the housing member  2000  may have more uniform structural properties (e.g., strength, stiffness, etc.) than would be the case if the speaker hole  2002  were offset vertically towards the top or bottom of the housing member  2000  (e.g., because the amount of material above and below the speaker hole  2002  would not be the same). 
       FIG. 20B  illustrates the speaker module  2001  removed from the device  2003 . In particular, the speaker module  2001  has been translated along a vertical path  2032  (relative to the orientation shown in  FIG. 20B ).  FIG. 20B  illustrates how the oblique angle of the sealing surface  2026  facilitates a removal direction (and thus also an installation direction) that requires little or no horizontal motion of the speaker module  2001 . In some cases, the speaker module  2001  can be placed in contact with the sealing surface  2026  (and/or against the sealing assembly  2018 ) with less than about 2.0 mm, about 1.5 mm, about 1.0 mm, about 0.5 mm, or about 0.25 mm of horizontal movement (relative to the orientation shown in  FIG. 20B ). 
       FIG. 20C  illustrates the device  2003  with another example sealing assembly  2034 . The sealing assembly  2034  may operate in a similar manner to the sealing assembly  2018 . The sealing assembly  2034  may include a carrier  2037  and a compliant material that defines a first compliant portion  2035  and a second compliant portion  2036 . The carrier  2037  may be a stiff material or combination of materials (relative to the compliant portions  2035 ,  2036 , for example). For example, the carrier  2037  may be formed from a polycarbonate material, a metal sheet, or the like. The first and second compliant portions  2035 ,  2036  may be formed from or include a foam, elastomer, rubber, or other material that can conform to and/or seal against the sealing surface  2026  of the bracket  2012  and a surface of the speaker module  2001 . The material that defines first and second compliant portions  2035 ,  2036  may be co-molded with the carrier  2037  to secure the compliant material to the carrier  2037  and produce a single assembly that can be attached to or otherwise assembled with the device  2003 . The compliant material that defines the first and second compliant portions  2035 ,  2036  may also or instead be secured to the carrier  2037  with adhesives or other fastening components. The compliant portions  2035 ,  2036  may be a monolithic structure (e.g., they may be different portions of a single compliant material structure), as shown in  FIG. 20C . 
       FIG. 20D  is a top view of the sealing assembly  2034 . The sealing assembly  2034  defines two openings  2038 , separated by a bridge portion  2040 . The carrier  2037  may define a ring-like structure and also include a bridge structure within the bridge portion  2040 , and the compliant material may at least partially encapsulate the carrier  2037 , including the ring-like structure and the bridge structure. The compliant material may also define a protrusion or bump along the bridge portion  2040 , which may increase the stiffness or structural rigidity of the bridge portion  2040 , while the bridge portion  2040  helps maintain the shape of the sealing assembly  2034  (e.g., resist deformation) when the sealing assembly  2034  is compressed between the speaker module  2001  and the bracket  2012 . 
     As described above, devices described herein may include numerous front-facing input and/or output devices, such as one or more front-facing cameras, ambient light sensors, speakers, depth sensors, light projectors, light sensors, and the like. Such devices may also include front-fired antennas that are front-facing or otherwise positioned along a front of the device (e.g., the front-fired millimeter-wave antenna  730 ,  FIG. 7 ). Such components may need to have substantially unobstructed access (e.g., optical and/or electromagnetic) to the exterior environment. In order to minimize or reduce the amount of front-facing area that must be devoted to such devices (and therefore to maximize or increase the amount of front-facing area that can be devoted to a display), multiple of such devices may be positioned in a single area along the front of the device. For example, a portion of the display may be cut away or otherwise shaped to define an area where such devices may be positioned. 
       FIG. 21A  illustrates a portion of an example device  2100 . The portion illustrated in  FIG. 21  may correspond to an area  21 - 21  in  FIG. 1A , though the same or a similar area may be found on other example devices described herein. 
     The device  2100  may include a display  2102 , which may be an embodiment of or otherwise represent other displays described herein, such as the display  103 ,  203 ,  303 ,  403 , or  503 . The display  2102  may define a recess  2104  along an edge of the display  2102 , thereby defining an area  2103  below a cover of the device  2100  (e.g., analogous to the cover  202 ) where input/output devices, antennas, and other components may be positioned without being placed under the display (and thus having to transmit/receive signals, sound, light, etc., through the display  2102 ). 
     The device  2100  may include, in the area  2103 , a front-facing camera  2112 , a speaker  2118 , a flood illuminator and proximity sensor module  2116 , an ambient light sensor  2110 , an infrared light projector  2114 , an infrared image capture device  2106 , and a front-fired antenna  2108 , some or all of which may be attached to a frame member or other structural component of the device  2100 . The speaker  2118  may be configured to be positioned next to or proximate a user&#39;s ear when the device  2100  is held to the user&#39;s face during a telephone call. Accordingly, the speaker  2118  may be aligned with an opening in the cover of the device  2100  or otherwise configured to emit sound through the cover. 
     The front-facing camera  2112  may include an optical lens, image sensor, and any other associated components, and may be configured to capture images. Images from the front-facing camera  2112  (e.g., still and/or video images captured by the user) may be stored in a memory of the device  2100 . 
     The device  2100  may also include an infrared light projector  2114  and an infrared image capture device  2106 , which may be components of a facial recognition sensor (e.g., the facial recognition sensors  252 ,  352 ,  452 ,  552 ). The infrared image capture device  2106  may include an optical lens, an infrared light sensor, and any other associated components to facilitate the sensing of an infrared image (e.g., an image of a real-world object, such as user&#39;s face, that is illuminated at least partially with infrared light). The infrared light projector  2114  may be configured to emit a pattern or array of infrared dots onto an object (e.g., a user&#39;s face), and the infrared image capture device  2106  may be configured to capture an image of the illuminated object. The captured image may include data corresponding to an array of depth points along the face of a user. The device  2100  may use the captured array of depth points to identify the user and/or authorize functionality on the device (e.g., unlocking the device, authorizing payments, etc.). More particularly, the device  2100  may compare the array of depth points to a key, and if the array of depth points matches the key (or satisfies a similarity threshold), the device  2100  may authenticate the user. 
     The device  2100  may also include an ambient light sensor  2110 . The ambient light sensor may determine properties of the ambient light conditions surrounding the device  2100 . The ambient light sensor  2110  may include a photosensitive element and a light guide configured to direct light onto the photosensitive element. The device  2100  may use information from the ambient light sensor to change, modify, adjust, or otherwise control the display  2102  (e.g., by changing a hue, brightness, saturation, or other optical aspect of the display based on information from the ambient light sensor). 
     The device  2100  may also include a flood illuminator and proximity sensor module  2116 . The flood illuminator and proximity sensor module  2116  may include a flood illuminator subsystem  2117 , which emits infrared light towards an object (e.g., the user&#39;s face). The flood illuminator subsystem  2117  may emit a substantially even and/or homogenous illumination pattern (as contrasted to the infrared light projector  2114  that may emit an array of discrete infrared dots). The flood illuminator subsystem  2117  is further described with respect to  FIGS. 21C-21D . The flood illuminator and proximity sensor module  2116  may also include a proximity sensor subsystem  2119  that may be configured to determine or estimate a distance between the device  2100  and an object (e.g., the user&#39;s face). Such information may be used, for example, to determine a parameter of the illumination from the flood illuminator and/or the infrared light projector  2114  (e.g., the amount, intensity, or other parameter of the infrared light emitted by such devices). 
     The device  2100  may also include in the area  2103  a front-fired antenna  2108 , which may be or may be an embodiment of the front-fired millimeter wave antenna  734 . The front-fired antenna  2108  may be configured to send and/or receive electromagnetic signals through the material of the cover (e.g., through the glass, ceramic, glass-ceramic, or polymer material of the cover). Accordingly, the thickness of the cover in the region over the front-fired antenna  2108  may be configured to reduce or limit attenuation of electromagnetic signals emitted and received by the front-fired antenna  2108 . In some cases, the thickness depends at least in part on the particular material of the cover. 
       FIG. 21B  shows a rear view of a top module  2121  of the device  2100 , including the area  2103 . The top module  2121  may be an embodiment of the top module  201 ,  301 ,  401 , and  501 , described above with respect to  FIGS. 2-5 . The top module  2121  includes a cover  2126  (which may be an embodiment of the cover  102  or other front-facing covers described herein) and additional components coupled to the cover  2126 . The additional components may include a back panel  2124  and a display (e.g., the display  2102  in  FIG. 21A ) between the back panel  2124  and the cover  2126 . Openings may be defined through components of the top module  2121  such that the cover  2126  is accessible from the back side of the top module  2121 . For example, the top module  2121  may include holes that reveal optical window portions  2127 ,  2128 ,  2129 , and  2130  of the cover  2126 , through which cameras, projectors, imaging devices, lenses, and/or other optical components may transmit and/or receive light. 
     The device  2100  may include brackets  2120 ,  2122 , which may be affixed to the top module  2121  (e.g., via welding, adhesive, brackets, fasteners, mechanical interlocking structures, or the like). A lens, optical sensor, and/or other component of the infrared image capture device  2106  may be mounted in and affixed to the bracket  2122 , and the front-facing camera  2112  may be mounted in and affixed to the bracket  2120 . The brackets  2120 ,  2122  may be used to ensure proper alignment of the optical components that are mounted to them. Further, the brackets  2120 ,  2122  may be rigidly coupled to the back panel  2124  (e.g., the brackets may be formed of or include metal and may be welded to a metal portion of the back panel  2124 ). Accordingly, the brackets  2120 ,  2122  may provide a dimensionally stable mounting structure for the optical components mounted thereto, thereby inhibiting motion of the optical components during use of the device or as a result of potentially damaging events such as drops or impacts. 
       FIG. 21C  is a partial cross-sectional view of the flood illuminator and proximity sensor module  2116  (also referred to as a flood/prox module  2116 ), viewed along line  21 C- 21 C in  FIG. 21A , showing an example configuration of the flood illuminator subsystem  2117 . The flood/prox module  2116  includes a cover structure  2132  that may cover and at least partially enclose the components of the flood illuminator subsystem  2117 . The cover structure  2132  may define an opening  2115  that allows light (e.g., infrared light) out of the cover structure  2132 . The flood illuminator subsystem  2117  may also include a light emitter  2130 , which may include a laser that produces infrared light to illuminate an object (e.g., a user&#39;s face) with a substantially even and/or homogenous illumination pattern of infrared light. The cover structure  2132  and the light emitter  2130  may be attached to a substrate or base  2134 . 
     The flood illuminator subsystem  2117  may also include a light transmissive component  2136  (also referred to as a diffuser) positioned above the light emitter  2130 . The light transmissive component may be formed from glass, polymer, sapphire, or another light transmissive material. The light transmissive component  2136  may include additional layers and/or components. For example, the light transmissive component  2136  may include filter layers, coatings, diffraction layers, circuit layers, mask layers, and the like. 
     The light transmissive component  2136  and the cover structure  2132  may be configured to prevent unfiltered and/or uncontrolled laser light (which may be emitted from the light emitter  2130 ) from exiting a device in which the flood illuminator subsystem  2117  is integrated. Accordingly, the device may monitor the flood illuminator subsystem  2117  to ensure that the light transmissive component  2136  and the cover structure  2132  are in place and have not been removed, moved out of position, damaged, or otherwise unable to adequately perform their functions (e.g., of blocking, filtering, attenuating, or otherwise affecting light emitted from the light emitter  2130 ). 
     A device may monitor the status of the light transmissive component  2136  and the cover structure  2132  by monitoring the status of conductive paths that extend through the light transmissive component  2136  and the cover structure  2132 . For example, as shown in  FIG. 21C , a conductive trace layer  2138  may be adhered or otherwise secured to the light transmissive component  2136 . The conductive trace layer  2138  may include a conductive trace, which may define a serpentine or other suitable pattern over the surface of the conductive trace layer  2138  and over the light transmissive component  2136  more generally. The conductive trace layer  2138  may include a metallic trace layer (e.g., copper, silver nanowire), indium tin oxide (ITO), or another suitable conductive material. A first wire  2140  may be conductively coupled to a first end of the conductive trace layer  2138 , and a second wire  2142  may be conductively coupled to a second end of the conductive trace layer  2138 , and the first and second wires  2140 ,  2142  may be conductively coupled to contact pads  2144 ,  2143 , respectively. The contact pads  2144 ,  2143 , the wires  2140 ,  2142 , and the conductive trace of the conductive trace layer  2138  may define a conductive path that may be monitored by the device. If the conductive path is severed, damaged, or otherwise physically affected (e.g., if the device detects an open circuit, short circuit, a change in resistance, or the like), the device may shut off the light emitter  2130 , as this condition may indicate that the light transmissive component  2136  has been broken, shifted, moved, damaged, or otherwise rendered less effective or ineffective. In some cases, the conductive path is part of a hardwired or dedicated failsafe circuit, such that if the conductive path is broken or otherwise negatively affected, the light emitter  2130  ceases operation (e.g., a power supply to the light emitter  2130  is terminated). 
     The flood/prox module  2116  may optionally include a coating  2137  positioned on the light transmissive component  2136  and on the conductive trace layer  2138 . The coating  2137  may be configured to protect the conductive trace layer  2138  from damage due to electrostatic discharge. For example, an electrostatic discharge that arcs to the conductive trace layer  2138  may damage the conductive trace layer  2138 , leading to the flood/prox module  2116  detecting a fault and/or ceasing operation. The coating  2137  may absorb or otherwise prevent energy from the electrostatic discharge from damaging the conductive trace layer  2138 . The coating  2137  may be any suitable coating, such as a conductive coating, an antireflective coating, or the like. The coating  2137  may include metals, transparent conductive oxides, or the like. The coating  2137  may be transparent, at least to spectra that are utilized by the flood/prox module  2116  and are transmitted through the light transmissive component  2136 . 
     The cover structure  2132  may also be monitored or otherwise integrated with a failsafe circuit so that movement, breakage, removal, or other damage to the cover structure  2132  may cause the light emitter  2130  to cease operations. For example, as shown in  FIG. 21D , which is a partial cross-sectional view of the flood illuminator subsystem  2117  viewed along line  21 D- 21 D in  FIG. 21A , the cover structure  2132  may have a conductor  2146  at least partially embedded in the material of the cover structure  2132  (which may be a polymer material) or otherwise attached to the cover structure  2132 . The conductor  2146  may be conductively coupled to contact pads  2148  and  2149 , thereby defining a conductive path that may be monitored by the device. If the conductive path is severed, damaged, or otherwise physically affected (e.g., if the device detects an open circuit, short circuit, a change in resistance, or the like), the device may shut off the light emitter  2130 , as this condition may indicate that the cover structure  2132  has been broken, shifted, moved, damaged, or otherwise rendered less effective or ineffective. In some cases, the conductive path through the conductor  2146  is part of a hardwired or dedicated failsafe circuit, such that if the conductive path is broken or otherwise negatively affected, the light emitter  2130  ceases operation (e.g., a power supply to the light emitter  2130  is terminated). 
       FIG. 21E  is a top view of the light transmissive component  2136  of the flood/prox module  2116 , showing an example configuration of a conductive trace  2181  of the conductive trace layer  2138 . The conductive trace  2181  may define a serpentine pattern along the light transmissive component  2136 . The serpentine pattern ensures that the conductive trace  2181  extends over much of the area of the light transmissive component  2136  so that a break or crack in the light transmissive component  2136  is likely to sever the conductive trace  2181  so that the crack or break can be detected (e.g., due to loss of continuity through the conductive trace  2181 ). The conductive trace  2181  may be conductively coupled to contacts  2180 ,  2182 , which may be solder pads (e.g., copper, gold, or other the like). The wires  2140 ,  2142  ( FIG. 21C ) may be conductively coupled (e.g., soldered) to the contacts  2180 ,  2182 , thereby conductively coupling the wires  2140 ,  2142  to the conductive trace  2181 . 
       FIG. 21F  is a top view of another example light transmissive component  2186  for the flood/prox module  2116 , showing an example configuration of a conductive trace  2185 . The conductive trace  2185  may have substantially the same shape and configuration as the conductive trace  2181 . The conductive trace  2185  may be conductively coupled to contacts  2183 ,  2184 , which may be solder pads (e.g., copper, gold, or other the like). The wires  2140 ,  2142  ( FIG. 21C ) may be conductively coupled (e.g., soldered) to the contacts  2183 ,  2184 , thereby conductively coupling the wires  2140 ,  2142  to the conductive trace  2185 . The contacts  2183 ,  2184  may each extend along two sides of the light transmissive component  2186 , as shown in  FIG. 21F , and may serve as electrostatic discharge collectors. For example, electrostatic discharges proximate the light transmissive component  2186  may be attracted to the contacts  2183 ,  2184 , such that the arc may tend to contact the contacts  2183 ,  2184  rather than the more delicate conductive trace  2185 . The relatively larger surface of the contacts  2183 ,  2184 , as well as the shape whereby the contacts extend together almost entirely around the periphery of the light transmissive component  2186 , increase the likelihood that an arc will be drawn to the contacts  2183 ,  2184 , and help dissipate the energy from the discharge, thereby reducing the likelihood of damage to the conductive trace  2185 . 
       FIG. 21G  illustrates the ambient light sensor  2110 , decoupled from a frame or other structural member of the device  2100 , and  FIG. 21H  illustrates an exploded view of the ambient light sensor  2110 . As noted above, the ambient light sensor may determine properties of the ambient light conditions surrounding the device  2100 , and the device  2100  may use information from the ambient light sensor to change, modify, adjust, or otherwise control the display of the device (e.g., by changing a hue, brightness, saturation, or other optical aspect of the display based on information from the ambient light sensor), or perform other actions (e.g., change notification settings based on an inferred condition, such as that the device is in a pocket or purse). 
     The ambient light sensor  2110  may include a frame member  2154 . A filter  2152  may be positioned in a recess defined by the frame member  2154 , and may cover an opening  2160  in the frame member. For example, the frame member  2154  may define a ledge  2158  (which may be recessed relative to a top surface  2156  of the frame member  2154 ), and the filter  2152  may be positioned on and optionally attached to (e.g., via an adhesive) to the ledge  2158 . The filter  2152  may be configured to filter out light in a particular wavelength range. For example, the filter  2152  may be an infrared cut filter, and may filter and/or attenuate light in an infrared range (and optionally in an ultraviolet range). The filter  2152  may be or may include a blue glass and/or other suitable material(s). A diffuser  2150  may be positioned on a surface of the filter  2152 . The diffuser  2150  may be a translucent material that diffuses incoming light or otherwise produces a more homogenous pattern of light, which may improve the operation of the ambient light sensor  2110  and provide for more even distribution of light on the photosensitive sensor of the ambient light sensor  2110 . In some cases, the functions of the filter  2152  and the diffuser  2150  may be performed by a single unitary component, such as a single piece of glass, plastic, ceramic, sapphire, or the like. 
     As noted above, the frame member  2154  may define an opening  2160  through which light may pass so as to fall on the sensor  2162 . The sensor  2162  may be coupled to a circuit board  2164 , which may include components such as an application specific integrated circuit (ASIC). Together, the sensor  2162  and the circuit board  2164  (which may include the ASIC and/or other electronic components) may be able to detect ambient light levels of the environment surrounding the device  2100 . 
     The ambient light sensor  2110  may be attached to a front cover of an electronic device. For example, an adhesive (e.g., an optically clear adhesive) may be positioned between and may adhere the top surface  2156  of the frame member  2154  and a portion of the front cover of a device. 
       FIG. 21I  illustrates another example ambient light sensor  2170 . The ambient light sensor  2170  is the same as the ambient light sensor  2110 , except that the ambient light sensor  2170  includes polymer structures  2174  along an outer portion of a frame member  2172 . The polymer structures  2174  may be molded to the frame member  2172 , or attached in another way (e.g., via an adhesive, ultrasonic weld, etc.). The polymer structures may be formed of or include a material having a Shore A durometer of between about 85 and about 95. The polymer structures may be formed from a one-part silicone, a two-part silicone, or another elastomeric material. The frame member  2172  may be formed from a glass-filled nylon, a polycarbonate, or another suitable polymer material. 
     The polymer structures  2174  may be more compliant and/or flexible than the frame member  2172 , and may be configured to form a light seal between the ambient light sensor and surrounding components. The polymer structures  2174  may also define mechanical interlock features, such as a lip  2176  (a same or similar lip may protrude from the opposite side of the ambient light sensor  2170 , or the lip  2176  may be the only lip). The mechanical interlock features of the polymer structures  2174  may be configured to mechanically interlock or otherwise engage with a frame member or other structure of the device  2100  to help retain the ambient light sensor  2170  in place during manufacturing and/or use of the device. 
     The top surfaces  2179  of the polymer structures  2174  may be higher than the top surface  2178  of the frame member  2172 . In some cases, the top surfaces  2179  of the polymer structures  2174  may contact the bottom surface of a front cover of a device. Accordingly, the top surfaces  2179  may act as bumpers that interface with the front cover. In some cases, the top surfaces  2179  of the polymer structures  2174  are softer than the frame member  2172 , and may help prevent scratching or damage to the front cover and/or coatings or masks on the front cover. They may also reduce the shock loading on the ambient light sensor  2170  and/or the front cover in the event of an impact or drop event. 
     The frame member  2172  may define interlock structures  2177  that the polymer structures  2174  engage to retain the polymer structures  2174  to the frame member  2172 . The polymer structures  2174  may be molded onto the frame member  2172  so that they form the corresponding interlock with the interlock structures  2177 . For example, a polymer material in a moldable state may be applied to the frame member  2172 , then a mold, having a cavity in the shape of the polymer structures  2174 , may be applied to the moldable polymer material. The moldable polymer material may thus engage the interlock structures  2177  and take on the shape of the mold cavity. 
     As described above, the mobile devices described herein may use batteries, such as lithium ion (e.g., lithium-ion polymer) batteries, to provide power to the electrical systems of the device. Such batteries may include power-producing components (e.g., electrodes and an electrolyte) contained inside a pouch. The pouch may be sealed or otherwise closed to enclose the one or more power-producing components. The pouch may include a metal portion, such as a metal foil layer. Accordingly, exposed edges of the pouch, such as where the pouch opening has been closed, may pose a shorting risk within the device. 
       FIGS. 22A-22E  illustrate example batteries in which edges of a pouch flap are covered and the flap is secured to the side of the battery, thereby helping to prevent or inhibit accidental shorts or other damage within the device due to exposed metal (e.g., conductive) material.  FIG. 22A  shows an example battery  2200  (which may be an embodiment of the battery  230  or any other battery described herein). The battery  2200  includes a pouch  2202  in which the power-producing components may be positioned. The pouch  2202  may include a flap  2204  that extends from a main portion of the battery  2200 . The flap  2204  may correspond to the opening of the pouch  2202  through which the internal components of the battery (e.g., electrodes and an electrolyte) are inserted into the pouch  2202 . In order to cover the exposed edges of the pouch material along the flap  2204 , a film  2206  (e.g., an adhesive tape) may be applied to the flap  2204 . The film  2206  may extend over the top and bottom surfaces of the flap  2204  and around the free end of the flap  2204 , thereby sealing the pouch closed (optionally in addition to an adhesive between the internal surfaces of the flap  2204 ) and covering the exposed edges of the pouch material. The film  2206  may be a nonconductive material. 
       FIG. 22B  shows the battery  2200  with the film  2206  applied to the flap  2204 . An adhesive may be applied to a surface  2210  of the film  2206  and/or a side surface  2211  of the pouch  2202 , and the flap  2204  may be folded up against the side surface  2211  of the pouch  2202  (as indicated by arrows  2208 ).  FIG. 22C  shows the battery  2200  with the flap  2204  folded against and adhered to the side surface  2211  of the pouch  2202 . 
       FIG. 22D  shows a partial cross-sectional view of the pouch  2202 , viewed along line  22 D- 22 D in  FIG. 22C .  FIG. 22D  shows an adhesive  2212  between the flap  2204  and the pouch  2202  and adhering the flap  2204  to the pouch  2202 . In this case, the adhesive  2212  contacts the side surface of the pouch  2202  (e.g., contacting the material of the pouch) and a surface of the film  2206  that covers the flap  2204 . (In some cases, the adhesive  2212  does not contact the actual portion of the pouch material that forms the flap  2204 , and only contacts the film  2206 , as shown in  FIG. 22D .) 
       FIG. 22E  is a partial cross-sectional view of another example battery  2220 , showing a view similar to that in  FIG. 22D . In this case, a polymer bead  2226  is applied along an edge of a flap  2224 . The polymer bead  2226  may be an epoxy or other material that may be applied in a flowable state and then allowed to cure or otherwise harden on the edge of the flap  2224 . The polymer bead  2226  may cover the edge of the flap  2224 , but may extend along less than the full length  2223  of the sides of the flap  2224 . For example, the polymer bead  2226  may extend along less than about 50%, less than about 40%, less than about 30%, less than about 20%, or less than about 10% of the length  2223  of the sides of the flap  2224 . Because the polymer bead  2226  does not cover the entirety of the sides of the flap  2224  (and in particular of the side of the flap  2224  facing the pouch  2222 ), the adhesive  2228  may contact the side of the pouch  2222  as well as the surface of the pouch material that forms the flap  2224  (e.g., instead of contacting a film, tape, or other layer that has been applied to the flap  2224 ). This may help reduce the dimensions of the battery and/or allow a larger internal pouch size for the same outer dimension of the battery. 
     Further, in both the battery  2200  and the battery  2220 , the flaps are not folded or rolled multiple times. Accordingly, the flaps  2204 ,  2224  may each be defined by two layers of the pouch material, rather than, for example four layers (which would be the case if the neck of the pouch were folded or rolled twice so that the edge of the flap doubled back and was facing and/or adjacent a fold region  2225 ). By avoiding the multiple folds or rolls, the outer dimensions of the batteries may be minimized or reduced. 
       FIG. 23A  illustrates an example logic board  2300  (which is an example of a circuit board assembly) that may be used in electronic devices as described herein. The logic board  2300  may be an embodiment of any of the logic boards described herein, such as the logic boards  220 ,  320 ,  420 ,  520 . The logic board  2300  may include one or more substrates, and processors, memory, and other circuit elements coupled to the substrate(s). The logic board  2300  may include provisions for a subscriber identity module (SIM). The logic board  2300  may include electrical contacts and/or a SIM tray assembly for receiving a physical SIM card and/or the logic board  2300  may include provisions for an electronic SIM. The logic board  2300  may be wholly or partially encapsulated to reduce the chance of damage due to an ingress of water or other fluid. The logic board  2300  may have a generally “L-shaped” configuration, in which a first portion  2360  extends along a first side of a battery (e.g., the batteries  230 ,  330 ,  430 ,  530 ) and a second portion  2361  extends along a second side of the battery. By extending along two sides of the battery, greater packing efficiency may be obtained and the logic board  2300  may be able to accommodate more components than a simple rectangular logic board, for example. 
     The logic board  2300  may include multiple substrates (e.g., circuit boards) that are stacked and coupled together in order to maximize the area available for electronic components and circuitry in a compact form factor. For example, the logic board  2300  may include a first substrate  2302  and a second substrate  2304  supported above the first substrate  2302 . The first and second substrates  2302 ,  2304  may also be referred to as circuit boards. Electrical components and/or circuit elements such as processors, memory, antenna circuitry, and the like, may be coupled to the first and/or the second substrates  2302 ,  2304 . For example,  FIG. 23A  shows a memory module  2316  (e.g., a NAND memory device) coupled to an exterior top surface of the second substrate  2304  and another component  2303  (e.g., a circuit element) coupled to the top surface of the first substrate  2302 , and  FIG. 23B  shows a processor  2332  coupled to the top surface of the first substrate  2302 . In some implementations, other or different circuit elements are coupled to the top surfaces of the first and/or second substrates. 
     The first and second substrates  2302 ,  2304  may be connected to one another via a wall structure  2308  (which supports the second substrate  2304  above the first substrate  2302 ). As described herein the first and second substrates  2302 ,  2304  may be soldered to conductive members (e.g., vias) in the wall structure  2308 , thereby allowing components on the first and second substrates  2302 ,  2304  to be conductively coupled to one another via the wall structure  2308 . For example, the memory module  2316  (or any other component on the second substrate  2304 ) may be conductively coupled to the processor via the vias in the wall structure  2308 . The wall structure  2308  may also surround electrical components (e.g., a processor  2332 ,  FIG. 23B ) and, along with the first and second substrates  2302 ,  2304 , define a substantially enclosed and optionally sealed internal volume (e.g.,  2321 ) in which the processor (and/or other components) may be protected. 
     The first substrate  2302  may be soldered to the wall structure  2308  using a first solder having a first melting temperature, while the second substrate  2304  may be soldered to the wall structure  2308  using a second solder having a second melting temperature. For example, the second melting temperature may be lower than the first melting temperature (e.g., between about 20 degrees Celsius and about 30 degrees Celsius lower than the first melting temperature). In some cases, the first solder is a high-temperature solder, and the second solder is a medium-temperature solder. 
     The logic board  2300  may also include a shroud  2306 , which may act as a shield (e.g., an EMI shield) and/or protective cover for the logic board  2300 . The shroud  2306  may also help maintain the physical connections of board-to-board connectors, which are used to interconnect components to or on the logic board  2300 . For example, the shroud  2306  may be secured to the logic board  2300  in a manner that presses on the board-to-board connectors to prevent them from becoming disconnected. The shroud  2306  may be attached to the logic board  2300  via screws or other fasteners. 
     The logic board  2300  may also include or be coupled to a flexible circuit element  2310 , which may conductively couple an antenna module (e.g., the antenna array  926  of the side-fired antenna  734 ) to electrical components attached to the logic board  2300 . The flexible circuit element  2310  may include an electrical connector  2341  (which may correspond to or be an embodiment of the electrical connector  940 ,  FIG. 9B ), which may connect with a corresponding electrical connector of the antenna array  926 . The flexible circuit element  2310  may also include a grounding and attachment lug  2340 , which may correspond to or be an embodiment of the grounding and attachment lug  938 ,  FIG. 9B ). 
     A front-fired antenna array (e.g., the antenna array of the front-fired antenna  730  or any other front-fired antenna system described herein) may be conductively coupled to the logic board  2300  via an electrical connector  2305 . More particularly, the electrical connector  2305  may connect with a corresponding electrical connector on a flexible circuit element to which the front-fired antenna array is coupled (e.g., the circuit board  740 ,  FIGS. 7 and 10A ). 
     The electrical connector  2305  may be coupled to the first substrate  2302  in an area of the first substrate  2302  that is not enclosed or surrounded by the wall structure  2308  or covered by the second substrate  2304 . The front- and side-fired antenna arrays that are coupled to the logic board  2300  via the connectors  2305 ,  2341 , may be millimeter-wave antenna arrays. Further, the rear-fired antenna array  2363  ( FIG. 23C ) coupled to the bottom side of the first substrate  2302  may also be a millimeter-wave antenna array. 
     The logic board  2300  may also include one or more films, foils, coatings, platings, layers, or other materials or components that provide EMI shielding functionality. For example, a metallic film (e.g., a conductive film with an adhesive) may be applied to the shroud  2306  and/or any other shrouds or surfaces of the logic board  2300 . The metallic film may include a nickel-iron ferromagnetic alloy, or any other suitable metal or conductive material. The metallic film may have a thickness between about 5 microns to about 20 microns, and may comprise a substrate layer (e.g., a polymer and/or adhesive layer) and a metallic layer laminated with the substrate layer. The metallic layer may be a different metal or composition than the shroud  2306 , which may be stainless steel. The substrate layer of the metallic film may be or may include a conductive adhesive to conductively couple the metallic layer to the shroud  2306 . 
     As another example, the shroud  2306  (and/or other shrouds of the logic board  2300 ) may be plated with a metallic plating. The plated shroud  2306  may therefore include a metal substrate (e.g., the shroud structure, which may be stainless steel) plated with a metal plating, where the plating may be a different metal or composition than the metal substrate. The metal substrate may have a thickness between about 150 microns and about 250 microns, and the metal plating may have a thickness between about 1 micron to about 5 microns. The metallic film and the metallic plating described above may increase the effectiveness of the EMI shielding of the shroud  2306 , as compared to a shroud without the metallic film or metallic plating. 
       FIG. 23B  shows an exploded view if the logic board  2300 . As noted above, the first substrate  2302  may include conductive pads  2328  which may be soldered to corresponding conductive components (e.g., vias) in the wall structure  2308 . For example, the conductive components may be at least partially encapsulated in a matrix material of the wall structure (e.g., a polymer, fiber-reinforced composite, etc.). The second substrate  2304  may also include conductive pads, like the conductive pads  2328 , that are soldered to the conductive components in the wall structure  2308 . The conductive path through the conductive pads and the wall structure  2308  may allow electrical interconnection between components such as the memory module  2316  and the processor  2332 . 
     The processor  2332  may be soldered to the first substrate  2302 . In some cases, a curable adhesive (e.g., an epoxy) or other curable material may be introduced between the processor  2332  and the top surface of the first substrate  2302  after the processor  2332  is soldered to the first substrate  2302 . The curable material may be configured to cure (e.g., harden) to reinforce the solder joints between the processor  2332  and the first substrate  2302 , and optionally to bond to both the processor  2332  and the first substrate  2302  (and thereby bonding the processor  2332  and the first substrate  2302  to one another). In order to retain the curable material in place, and prevent it from flowing or wicking along to other areas of the logic board  2300  where the curable material is not intended to be, a barrier  2330  (or dam) may be applied to the top surface of the first substrate  2302 . The barrier  2330  may extend partially or fully around the processor  2332 , such that when the curable material is flowed into the area between the first substrate  2302  and the processor  2332 , it is prevented from flowing outside of the barrier  2330 . As shown, the barrier  2330  extends along three out of four sides of the processor  2332 . In other cases, the barrier extends along one, two, or four sides of the processor  2332 . 
     The barrier  2330  may be a bead of solder that is deposited on the first substrate  2302 . The barrier  2330  may have a height between about 0.05 mm to about 0.07 mm, and may be set apart from the sides of the processor  2332  by a distance between about 0.10 mm to 0.15 mm. The barrier  2330  may have a width between about 0.15 mm and 0.20 mm. In some cases, an inner surface of the wall structure may be set apart from a side of the processor  2332  by a distance between about 0.2 mm and about 0.4 mm, or a distance between about 0.25 mm and about 0.35 mm. 
     The barrier  2330  may be applied after the wall structure  2308  is attached to the first substrate  2302 , and may abut or contact the wall structure  2308 . By forming the barrier  2330  from a bead of solder, the wall structure  2308  may be positioned closer to the barrier  2330  than might be possible if other components (e.g., sacrificial or non-functional electrical components) were used to define a barrier or dam-type structure. Accordingly, using the solder bead for the barrier  2330  may allow the first substrate  2302  (and the logic board  2300  more generally) to be smaller (at least relative to logic boards with other dam or barrier configurations). 
     In some cases, a curable material may be introduced between the wall structure  2308  and the top surface of the first substrate  2302 , and between the wall structure  2308  and the bottom surface of the second substrate  2304 . The curable material may be used to reinforce the solder joints between the wall structure  2308  and the first and second substrates  2302 ,  2304 . To assist in the introduction of the curable material into the space between the wall structure  2308  and the surfaces of the first and second substrates  2302 ,  2304  to which the wall structure  2308  is soldered, the logic board  2300  may include features to facilitate the deposition, injection, and/or introduction of the curable material into the space between the substrates and the wall structure. For example, the second substrate  2304  may include a cutout region  2311  that exposes at least part of the top surface  2313  of the wall structure  2308 . As another example, the wall structure  2308  may include a ledge feature  2309  that is exposed even after the second substrate  2304  is soldered or otherwise secured to the wall structure  2308 . After the second substrate  2304  is soldered to the wall structure  2308 , a curable material may be introduced into the gap between the surface  2313  of the wall structure  2308  and the bottom surface of the second substrate  2304  by placing the curable material on the surface  2313  in the area of the recess  2311 , and/or on the ledge  2309 . The curable material, which may be in a flowable state, may be wicked or otherwise drawn into the gap between the second substrate  2304  and the wall structure  2308  (e.g., via capillary action), thereby delivering the curable material to the target locations and/or positions between the components. The curable material may flow around solder joints and into gaps between discrete solder joints along the wall-substrate interface. The curable material may then be allowed to cure (e.g., harden), thereby reinforcing the solder joints and adhering the second substrate  2304  to the wall structure  2308 . 
     While  FIG. 23B  shows one example of each type of feature, it will be understood that a logic board may include multiple instances of these features, including combinations of recesses and ledges, to facilitate the introduction of the curable material into the desired locations. Further,  FIG. 23B  shows features positioned to facilitate introduction (e.g., via wicking) of the curable material into a space between the wall structure  2308  and the second substrate  2304 , though it will be understood that the same or similar features may be implemented on the first substrate  2302  or otherwise configured to facilitate wicking of the curable material into the gap between the top surface of the first substrate  2302  and the bottom surface of the wall structure  2308 . 
     The flexible circuit element  2310  may be soldered to a bottom surface of the first substrate  2302 . In particular, the flexible circuit element  2310  may include an attachment portion  2334  with a plurality of solder points or vias (e.g., vias  2336 ) that are soldered to corresponding solder pads on the bottom of the first substrate  2302  (e.g., solder pads  2345 ,  FIG. 23C ). The flexible circuit element  2310  may include a liquid crystal polymer substrate, and the vias (e.g., the vias  2336 ) may be solid metal (e.g., copper). By providing solid metal vias, the physical connection between the vias and the logic board may be stronger than with other types of conductive vias. Adhesive  2338  may also be used to bond the flexible circuit element  2310  to the bottom surface of the first substrate  2302 . By using the adhesive  2338 , the physical coupling between the flexible circuit element  2310  and the first substrate  2302  may be stronger than with the solder alone. 
     The logic board  2300  may be coupled to another component of a device via one or more fasteners, such as screws. Due in part to the relative importance of the logic board to the operation of the device, it is advantageous to provide high strength connections to ensure that the logic board  2300  remains structurally coupled to the device even through drops or other potentially damaging events. In some areas of the logic board  2300 , fasteners, such as screws, may extend through holes in the first and/or the second substrates  2302 ,  2304  and be secured to another component of the device (e.g., a housing or enclosure structure, a frame, etc.). In some cases, the logic board  2300  may include an attachment feature  2320  that is securely attached to the logic board  2300  and includes an attachment tab  2322  with a hole  2324  to accept a fastener (e.g., a screw) to secure the logic board  2300  to the device. 
       FIG. 23C  shows the bottom surface of the logic board  2300 . As shown, the attachment feature  2320  includes a mounting portion  2318  that is attached to the bottom surface of the logic board  2300 . For example, the attachment feature  2320  may be soldered to the bottom surface of the first substrate  2302 . In some cases, the entire area of the mounting portion  2318  (e.g., the triangular portion of the attachment feature  2320 ) may be soldered to a metal portion on the bottom surface of the logic board  2300 . The attachment feature  2320  may also be secured to the first substrate  2302  via a fastener assembly, which includes a socket portion  2342 . 
       FIG. 23D  is a partial cross-sectional view of the logic board  2300 , viewed along line  23 D- 23 D in  FIG. 23A , illustrating a fastener assembly that is configured to secure the attachment feature  2320  to the logic board  2300 , as well as help retain the first and second substrates of the logic board  2300  together, and providing an attachment feature for the shroud  2306 . For example, a socket portion  2342  may extend through a hole in the mounting portion  2318  of the attachment feature and through a hole in the first substrate  2302 . A bolt portion  2314  may extend through a hole in the second substrate  2304 . The socket portion  2342  may define a flange portion  2350  that contacts the mounting portion  2318  (and is optionally soldered, adhered, welded, or otherwise attached to the mounting portion  2318 ), and the bolt portion  2314  may define a flange portion  2353  that contacts the second substrate  2304 . The bolt portion  2314  may be threaded into a threaded hole  2352  of the socket portion  2342 , thereby clamping the first and second substrates  2302 ,  2304  and the mounting portion  2318  between the flange portions  2350 ,  2353 . As shown in  FIG. 23D , an intermediate structure  2348  may be positioned between the first and second substrates  2302 ,  2304 . The intermediate structure  2348  may be a portion of the wall structure  2308 , or it may be a separate component such as a spacer, washer, ferrule, or the like. In some cases, the socket portion  2342  and the bolt portion  2314  may be configured to seat or bottom-out against one another (e.g., to define a predetermined distance between the flange portions  2353  and  2350  when the socket and bolt portions are fully threaded together) to mitigate the possibility of over-tightening the fastener assembly, which could crush or otherwise damage the substrates  2302 ,  2304  and/or the intermediate structure  2348 . 
     As shown in  FIG. 23D , the bolt portion  2314  may also define a hole  2354  (e.g., a threaded hole) that is configured to receive screw  2312 . The screw  2312  may be configured to clamp the shroud  2306  between a surface of the screw  2312  and a surface of the bolt portion  2314 . 
     With reference to  FIG. 23C , the logic board  2300  may also include a stiffener or reinforcement plate  2346  attached to the bottom surface of the first substrate  2302 . The stiffener plate  2346  may be attached to the first substrate  2302  via an adhesive, solder, fasteners, and/or other suitable attachment techniques. The stiffener plate  2346  may be formed from metal, carbon fiber, a polymer, or any other suitable material. The stiffener plate  2346  may reinforce the first substrate  2302  (and the attachment region  2344  more specifically) to increase the overall stiffness of the first substrate  2302 . For example, twisting or other distortion of the first substrate  2302  in the vicinity of the attachment region  2344  may result in the solder joints between the first substrate  2302  and the flexible circuit element  2310  breaking. The stiffener plate  2346  may increase the resistance of the first substrate  2302  to flexing, twisting, or other distortions or deformations, thereby improving the durability and/or reliability of the conductive coupling between the flexible circuit element  2310  and the first substrate  2302 . 
     The stiffener plate  2346  may define an opening  2347  that exposes an attachment region  2344  where the flexible circuit element  2310  is attached to the first substrate  2302 . The opening  2347  may extend around the outer periphery of the attachment region  2344  (e.g., along four sides of the attachment region  2344 ). As noted above, solder pads  2345  may be positioned in the attachment region  2344  to facilitate a conductive coupling with the flexible circuit element  2310 . The logic board  2300  may also include a rear-fired antenna array  2363 , which may be conductively coupled to the first substrate  2302  via one or more solder connections as well. The rear-fired antenna array  2363  may correspond to the rear-fired antenna array  732 , or any other rear-fired antenna array described herein. 
       FIG. 23E  is a partial cross-sectional view of the logic board  2300 , viewed along line  23 E- 23 E in  FIG. 23A , illustrating the interfaces between the first and second substrates  2302 ,  2304  and the wall structure  2308 . As noted above, the wall structure  2308  may include conductive vias, such as the conductive via  2355 , within a matrix material  2357 . The matrix material may be a polymer, fiber-reinforced polymer, or the like, and the conductive via  2355  may be a metal, such as copper, gold, or any other suitable conductor. The first substrate  2302  may include solder pads, such as the solder pad  2362 , and the second substrate may include solder pads, such as the solder pad  2361 . The solder pads  2361 ,  2362  may be conductively coupled to other components that are attached to the first and second substrates  2302 ,  2304 , such as a processor, memory module, or any other suitable component. The conductive via  2355  may be soldered to the solder pad  2362  via a first solder material  2359  having a first melting temperature, and to the solder pad  2361  via a second solder material  2358  having a second melting temperature that is lower than the first melting temperature. For example, the second melting temperature may be between about 20 degrees Celsius and about 30 degrees Celsius lower than the first melting temperature. In some cases, the first solder material  2359  is a high-temperature solder, and the second solder material  2358  is a medium-temperature solder. The first solder material and the second solder material may both exhibit a ductile failure mode (as opposed to a brittle failure mode) at strain rates of about 100 s −1 . For example, when subjected to strain rates of about 100 s −1 , both the first solder material and the second solder material may exhibit plastic deformation after a yield point, such that a stress-strain curve for the first and second solder materials includes at least one region, after a yield point, of at least relatively constant stress across an increasing range of strains. 
     As noted above, a curable material  2369  may be introduced between the wall structure  2308  and the top surface of the first substrate  2302 , and a curable material  2356  may be introduced between the wall structure  2308  and the bottom surface of the second substrate  2304 . As shown, the curable materials  2360 ,  2356  may flow or otherwise extend around the solder materials  2358 ,  2359 , and may adhere to the surfaces of the wall structure  2308  and substrates  2302 ,  2304 . The curable materials  2360 ,  2356  may be the same or different materials, and may be an epoxy, adhesive, or other curable material. 
       FIG. 23F  is a partial cross-sectional view of the logic board  2300 , viewed along line  23 F- 23 F in  FIG. 23B .  FIG. 23F  illustrates an example configuration of the barrier  2330  or dam that is positioned on the first substrate  2302  and extending at least partially around an outer periphery of a circuit element such as the processor  2332 . As noted above, the barrier  2330  may be formed of a solder material, such as a high-temperature solder. The barrier  2330  may have a height (e.g., along the vertical direction as shown in  FIG. 23F ) between about 0.05 mm and about 0.07 mm. In some cases, the barrier  2230  has a height between about 0.04 mm and about 0.1 mm. 
     In some cases, the wall structure  2308  contacts a side of the barrier  2330 . For example, the barrier  2330  may be deposited onto the first substrate  2302  after the wall structure  2308  is attached to the first substrate  2302 , and the barrier  2330  may abut or flow against the wall structure  2308 . An inner surface  2364  of the wall structure  2308  may be set apart from a side of the circuit element (e.g., the processor  2332 ) by a distance between about 0.2 mm and 0.4 mm. In some cases, the inner surface  2364  of the wall structure  2308  is set apart from a side of the circuit element (e.g., the processor  2332 ) by a distance less than about 1.0 mm. 
     The barrier  2330  may be configured to limit a spread of a liquid adhesive along the first substrate  2302 . For example, a curable liquid adhesive (e.g., an epoxy) may be flowed between the circuit element (e.g., the processor  2332 ) and the surface of the first substrate  2302 . Once cured, the adhesive may reinforce the solder joints between the circuit element and the first substrate  2302 , and may increase the strength of the mechanical attachment between the circuit element and the first substrate  2302 . The barrier  2330  is configured to limit a spread of a liquid adhesive along the first circuit board as it is flowed between the circuit element and the surface of the first substrate  2302 . For example, the barrier  2330  may help contain the liquid adhesive below the circuit element, such that it does not flow away and become too thin or distributed to successfully reinforce the solder joints, and also help prevent the liquid adhesive from flowing onto surfaces or components that are not intended to be contacted by the adhesive. 
     The logic board  2300  in  FIGS. 23A-23B  illustrates one example technique for forming a multi-level component, where some electrical components (e.g., the memory module  2316 ) is positioned on a substrate above other electrical components (e.g., the processor  2332 ). This configuration may help reduce the footprint of the logic board  2300  by stacking components rather than requiring them to be positioned next to each other on the same substrate.  FIGS. 24A-24C  illustrate other example structures whereby components may be stacked to help reduce the overall footprint of a logic board or circuit board, and/or to otherwise simplify or improve the operation or manufacturing of the device. 
       FIG. 24A , for example, shows an exploded view of a portion of a logic board, showing an example lofting or two-level configuration for electrical components. In particular,  FIG. 24A  shows a first substrate  2400  (e.g., a circuit board) with a processor  2401  positioned on the surface of the first substrate  2400 . The processor  2401  may be an embodiment of the processor  2332 , and the first substrate  2400  may be an embodiment of the first substrate  2302 . A frame member  2407  may be attached to the first substrate  2400  and may extend around a perimeter of the processor  2401  (e.g., side walls of the frame member may extend around a perimeter of the processor  2401 ). The frame member  2407  may be soldered to the first substrate  2400 , and may include vias or other conductive paths to conductively couple the frame member  2407  and any circuit boards and/or electrical components (e.g., a memory module  2409 ) to the first substrate  2400 . 
     A second substrate  2408  may be attached to the frame member  2407 . For example, the second substrate  2408  may be soldered to the frame member  2407 . The solder connections between the frame member  2407  and the first and second substrates  2400 ,  2408  may structurally and conductively couple the frame member  2407  and the first and second substrates  2400 ,  2408  together. In some cases, after the frame member  2407  is attached to the first substrate  2400  and before the second substrate  2408  is attached to the frame member  2407 , a thermal paste, gel, or other material may be applied to the processor  2401  to aid in conducting heat away from the processor  2401 . In such cases, the thermal material may be dispensed through the opening in the frame member  2407 . 
     The frame member  2407  and the first and second substrates  2400 ,  2408  may define a physical and EMI shield around the processor  2401 . For example, the conductive materials (e.g., vias, traces, etc.) in the first and second substrates  2400 ,  2408 , as well as the metal material of the frame member  2407 , may be conductively coupled together, thereby forming a structure that can prevent or inhibit the passage of electromagnetic signals or other interference either from or to the processor  2401  (or any electrical component(s) within the area defined by the frame member  2407  and the first and second substrates  2400 ,  2408 . 
       FIG. 24B  illustrates another example configuration of a multi-level circuit element arrangement. In particular,  FIG. 24B  shows a first substrate  2410  (e.g., a circuit board) with a processor  2411  positioned on the surface of the first substrate  2410 . The processor  2411  may be an embodiment of the processor  2332 , and the first substrate  2410  may be an embodiment of the first substrate  2402 . A shield member  2412  may be attached to the first substrate  2410  and may extend around a perimeter of the processor  2411  and over a top of the processor  2411  (e.g., the shield member  2412  defines side walls and a top wall that substantially enclose the processor  2411 ). The shield member  2412  may be soldered or otherwise secured to the first substrate  2410  (e.g., via fasteners, adhesives, etc.). The shield member  2412  may be formed of or include metal or another conductive material, thereby providing EMI shielding properties. 
     A second substrate  2418 , such as a flexible circuit board, may have a memory module  2419  conductively coupled thereto, and the second substrate  2418  may be attached to the top wall of the shield member  2412 . For example, the second substrate  2418  may be adhered to the top of the shield member  2412  via an adhesive  2413  (which may be a conductive adhesive). The second substrate  2418  may also include a connector  2416 , which may conductively couple the memory module  2419  (or any electrical component on the second substrate  2418 ) to the first substrate  2410  and thereby to any of the electrical components on the first substrate  2410  (e.g., the processor  2411 ). Because the second substrate  2418  includes the connector  2416 , the shield member  2412  does not need to provide vias, traces, or other conductive paths to conductively couple the electrical components of the first and second substrates  2410 ,  2418  (though such conductive paths may be provided if desired, and the second substrate  2418  may be conductively coupled to the shield member  2412  via a conductive adhesive  2413  such as to provide a common electrical ground between the shield member  2412  and conductive materials in the second substrate  2418 ). 
     As noted above, a thermal gel, paste, or other material may be applied to the processor  2411  to aid in conducting heat away from the processor  2411 . However, thermal gels, pastes, or other materials may be sensitive to heat (e.g., it may degrade the material, cause it to flow away from its intended location, or the like). Because the shield member  2412  does not have an opening in the top wall, the thermal material may be dispensed onto the processor  2411  prior to the shield member  2412  being attached to the first substrate  2410 . Accordingly, the shield member  2412  may be secured to the first substrate  2410  using a medium or low temperature solder operation, thereby helping to limit the amount of heat that the thermal gel is exposed to. Additionally, because the second substrate  2418  is attached via an adhesive, there is no additional soldering operation required to secure the second substrate  2418  to the shield member  2412 , thereby further limiting the exposure of the thermal gel to heat. 
       FIG. 24C  illustrates another example configuration of a multi-level circuit element arrangement. In particular,  FIG. 24C  shows a first substrate  2420  (e.g., a circuit board) with a processor  2421  positioned on the surface of the first substrate  2420 . The processor  2421  may be an embodiment of the processor  2332 , and the first substrate  2420  may be an embodiment of the first substrate  2402 . A frame member  2422  may be attached to the first substrate  2420  and may extend around a perimeter of the processor  2421 . The frame member  2422  may be similar to the shield member  2412 , except that the frame member  2422  may define an opening along the top of the frame member  2422  (e.g., similar to the configuration in  FIG. 24A ). The frame member  2422  may be soldered or otherwise secured to the first substrate  2420  (e.g., via fasteners, adhesives, etc.). The opening along the top of the frame member  2422  may allow a curable material to be introduced between the processor  2421  and the first substrate  2420  (as described above with respect to  FIG. 23B ) after the frame member  2422  is attached to the first substrate  2420 . 
     A second substrate  2428 , such as a flexible circuit board, may have a memory module  2429  conductively coupled thereto, and the second substrate  2428  may be attached to the top wall of the frame member  2422 . For example, the second substrate  2428  may be adhered to the top of the frame member  2422  via an adhesive (which may be a conductive adhesive), by soldering, with fasteners, or the like. The second substrate  2428  may also include a connector  2426 , which may conductively couple the memory module  2429  (or any electrical component on the second substrate  2428 ) to the first substrate  2420  and thereby to any of the electrical components on the first substrate  2420  (e.g., the processor  2421 ). Because the second substrate  2428  includes the connector  2426 , the frame member  2422  does not need to provide vias, traces, or other conductive paths to conductively couple the electrical components of the first and second substrates  2420 ,  2428 . In some cases, however, the frame member  2422 , which may be formed of or include metal or another conductive material, may conductively couple to conductive materials in the second substrate  2428  so that the frame member  2422  and the second substrate  2428  can cooperate to provide EMI shielding functionality. For example, the frame member  2422  may be conductively coupled to the second substrate  2428  (e.g., via solder, conductive adhesive, etc.) to provide a common electrical ground to the frame member  2422  and the second substrate  2428 , thereby facilitating EMI shielding functionality. 
     As noted above, a thermal gel, paste, or other material may be applied to the processor  2421  to aid in conducting heat away from the processor  2421 . Because the frame member  2422  has an opening in the top wall, the thermal material may be dispensed onto the processor  2421  after the frame member  2422  is attached to the first substrate  2420 . 
     In some cases, the height of a top surface  2430  of the frame member  2422 , when the frame member  2422  and the processor  2421  are attached to the first substrate  2420 , is substantially flush with or recessed relative to a top surface  2431  of the processor  2421 . In such cases, the bottom surface of the second substrate  2428  may be in contact with or only a small distance (e.g., around 50 microns, around 100 microns, or the like) above the top surface  2431  of the processor  2421 . In cases where the top surface  2430  is recessed relative to (e.g., below) the top surface  2431  of the processor  2421 , an adhesive on the top surface  2430  may adhere the second substrate  2428  to the frame member  2422 , and also increase the effective height of the frame member  2422  such that the bottom surface of the second substrate  2428  is contacting or above the top surface  2431  of the processor  2421  (despite the top surface  2430  being recessed relative to the top surface  2431  of the processor  2421 ). 
     While  FIGS. 24A-24C  illustrate a processor and a memory module, these are merely example electrical components that may be coupled to a logic board using the configurations shown. In other cases, the position of the processor and the memory module may be reversed, and/or other types of electrical component(s) may be used, such as integrated circuits, ASICs, analog chips, or any other suitable electrical component. 
       FIG. 25  depicts an example schematic diagram of an electronic device  2500 . The electronic device  2500  may be an embodiment of or otherwise represent the device  100  (or other devices described herein, such as the devices  140 ,  200 ,  300 ,  400 ,  500 ,  600 ,  700 , or the like). The device  2500  includes one or more processing units  2501  that are configured to access a memory  2502  having instructions stored thereon. The instructions or computer programs may be configured to perform one or more of the operations or functions described with respect to the electronic devices described herein. For example, the instructions may be configured to control or coordinate the operation of one or more displays  2508 , one or more touch sensors  2503 , one or more force sensors  2505 , one or more communication channels  2504 , one or more audio input systems  2509 , one or more audio output systems  2510 , one or more positioning systems  2511 , one or more sensors  2512 , and/or one or more haptic feedback devices  2506 . 
     The processing units  2501  of  FIG. 25  may be implemented as any electronic device capable of processing, receiving, or transmitting data or instructions. For example, the processing units  2501  may include one or more of: a microprocessor, a central processing unit (CPU), an application-specific integrated circuit (ASIC), a digital signal processor (DSP), or combinations of such devices. As described herein, the term “processor” is meant to encompass a single processor or processing unit, multiple processors, multiple processing units, or other suitably configured computing element or elements. The processing units  2501  may be coupled to a logic board, such as the logic boards  220 ,  320 ,  420 ,  520 , of  FIG. 2-5 , or  2300  of  FIGS. 23A-23C . 
     The memory  2502  can store electronic data that can be used by the device  2500 . For example, a memory can store electrical data or content such as, for example, audio and video files, images, documents and applications, device settings and user preferences, programs, instructions, timing and control signals or data for the various modules, data structures or databases, and so on. The memory  2502  can be configured as any type of memory. By way of example only, the memory can be implemented as random access memory, read-only memory, Flash memory, removable memory, or other types of storage elements, or combinations of such devices. The memory  2502  may be coupled to a logic board, such as the logic boards  220 ,  320 ,  420 ,  520 , of  FIG. 2-5 , or  2300  of  FIGS. 23A-23C . 
     The touch sensors  2503  may detect various types of touch-based inputs and generate signals or data that are able to be accessed using processor instructions. The touch sensors  2503  may use any suitable components and may rely on any suitable phenomena to detect physical inputs. For example, the touch sensors  2503  may be capacitive touch sensors, resistive touch sensors, acoustic wave sensors, or the like. The touch sensors  2503  may include any suitable components for detecting touch-based inputs and generating signals or data that are able to be accessed using processor instructions, including electrodes (e.g., electrode layers), physical components (e.g., substrates, spacing layers, structural supports, compressible elements, etc.) processors, circuitry, firmware, and the like. The touch sensors  2503  may be integrated with or otherwise configured to detect touch inputs applied to any portion of the device  2500 . For example, the touch sensors  2503  may be configured to detect touch inputs applied to any portion of the device  2500  that includes a display (and may be integrated with a display). The touch sensors  2503  may operate in conjunction with the force sensors  2505  to generate signals or data in response to touch inputs. A touch sensor or force sensor that is positioned over a display surface or otherwise integrated with a display may be referred to herein as a touch-sensitive display, force-sensitive display, or touchscreen. 
     The force sensors  2505  may detect various types of force-based inputs and generate signals or data that are able to be accessed using processor instructions. The force sensors  2505  may use any suitable components and may rely on any suitable phenomena to detect physical inputs. For example, the force sensors  2505  may be strain-based sensors, piezoelectric-based sensors, piezoresistive-based sensors, capacitive sensors, resistive sensors, or the like. The force sensors  2505  may include any suitable components for detecting force-based inputs and generating signals or data that are able to be accessed using processor instructions, including electrodes (e.g., electrode layers), physical components (e.g., substrates, spacing layers, structural supports, compressible elements, etc.) processors, circuitry, firmware, and the like. The force sensors  2505  may be used in conjunction with various input mechanisms to detect various types of inputs. For example, the force sensors  2505  may be used to detect presses or other force inputs that satisfy a force threshold (which may represent a more forceful input than is typical for a standard “touch” input) Like the touch sensors  2503 , the force sensors  2505  may be integrated with or otherwise configured to detect force inputs applied to any portion of the device  2500 . For example, the force sensors  2505  may be configured to detect force inputs applied to any portion of the device  2500  that includes a display (and may be integrated with a display). The force sensors  2505  may operate in conjunction with the touch sensors  2503  to generate signals or data in response to touch- and/or force-based inputs. 
     The device  2500  may also include one or more haptic devices  2506  (e.g., the haptic actuator  222 ,  322 ,  422 ,  522  of  FIG. 2-5 or 1804, 1900, 1920  of  FIGS. 18-19B ). The haptic device  2506  may include one or more of a variety of haptic technologies such as, but not necessarily limited to, rotational haptic devices, linear actuators, piezoelectric devices, vibration elements, and so on. In general, the haptic device  2506  may be configured to provide punctuated and distinct feedback to a user of the device. More particularly, the haptic device  2506  may be adapted to produce a knock or tap sensation and/or a vibration sensation. Such haptic outputs may be provided in response to detection of touch and/or force inputs, and may be imparted to a user through the exterior surface of the device  2500  (e.g., via a glass or other surface that acts as a touch- and/or force-sensitive display or surface). 
     The one or more communication channels  2504  may include one or more wireless interface(s) that are adapted to provide communication between the processing unit(s)  2501  and an external device. The one or more communication channels  2504  may include antennas (e.g., antennas that include or use the housing members of the housing  104  as radiating members), communications circuitry, firmware, software, or any other components or systems that facilitate wireless communications with other devices. In general, the one or more communication channels  2504  may be configured to transmit and receive data and/or signals that may be interpreted by instructions executed on the processing units  2501 . In some cases, the external device is part of an external communication network that is configured to exchange data with wireless devices. Generally, the wireless interface may communicate via, without limitation, radio frequency, optical, acoustic, and/or magnetic signals and may be configured to operate over a wireless interface or protocol. Example wireless interfaces include radio frequency cellular interfaces (e.g., 2G, 3G, 4G, 4G long-term evolution (LTE), 5G, GSM, CDMA, or the like), fiber optic interfaces, acoustic interfaces, Bluetooth interfaces, infrared interfaces, USB interfaces, Wi-Fi interfaces, TCP/IP interfaces, network communications interfaces, or any conventional communication interfaces. The one or more communications channels  2504  may also include ultra-wideband interfaces, which may include any appropriate communications circuitry, instructions, and number and position of suitable UWB antennas. 
     As shown in  FIG. 25 , the device  2500  may include a battery  2507  that is used to store and provide power to the other components of the device  2500 . The battery  2507  may be a rechargeable power supply that is configured to provide power to the device  2500 . The battery  2507  may be coupled to charging systems (e.g., wired and/or wireless charging systems) and/or other circuitry to control the electrical power provided to the battery  2507  and to control the electrical power provided from the battery  2507  to the device  2500 . 
     The device  2500  may also include one or more displays  2508  configured to display graphical outputs. The displays  2508  may use any suitable display technology, including liquid crystal displays (LCD), organic light emitting diodes (OLED), active-matrix organic light-emitting diode displays (AMOLED), or the like. The displays  2508  may display graphical user interfaces, images, icons, or any other suitable graphical outputs. The display  2508  may correspond to a display  203 ,  303 ,  403 ,  503  of  FIGS. 2-5 . 
     The device  2500  may also provide audio input functionality via one or more audio input systems  2509 . The audio input systems  2509  may include microphones, transducers, or other devices that capture sound for voice calls, video calls, audio recordings, video recordings, voice commands, and the like. 
     The device  2500  may also provide audio output functionality via one or more audio output systems (e.g., speakers)  2510 , such as the speaker systems  224 ,  324 ,  424 ,  524  of  FIGS. 2-5 . The audio output systems  2510  may produce sound from voice calls, video calls, streaming or local audio content, streaming or local video content, or the like. 
     The device  2500  may also include a positioning system  2511 . The positioning system  2511  may be configured to determine the location of the device  2500 . For example, the positioning system  2511  may include magnetometers, gyroscopes, accelerometers, optical sensors, cameras, global positioning system (GPS) receivers, inertial positioning systems, or the like. The positioning system  2511  may be used to determine spatial parameters of the device  2500 , such as the location of the device  2500  (e.g., geographical coordinates of the device), measurements or estimates of physical movement of the device  2500 , an orientation of the device  2500 , or the like. 
     The device  2500  may also include one or more additional sensors  2512  to receive inputs (e.g., from a user or another computer, device, system, network, etc.) or to detect any suitable property or parameter of the device, the environment surrounding the device, people or things interacting with the device (or nearby the device), or the like. For example, a device may include temperature sensors, biometric sensors (e.g., fingerprint sensors, photoplethysmographs, blood-oxygen sensors, blood sugar sensors, or the like), eye-tracking sensors, retinal scanners, humidity sensors, buttons, switches, lid-closure sensors, or the like. 
     To the extent that multiple functionalities, operations, and structures described with reference to  FIG. 25  are disclosed as being part of, incorporated into, or performed by the device  2500 , it should be understood that various embodiments may omit any or all such described functionalities, operations, and structures. Thus, different embodiments of the device  2500  may have some, none, or all of the various capabilities, apparatuses, physical features, modes, and operating parameters discussed herein. Further, the systems included in the device  2500  are not exclusive, and the device  2500  may include alternative or additional systems, components, modules, programs, instructions, or the like, that may be necessary or useful to perform the functions described herein. 
     As described above, one aspect of the present technology is the gathering and use of data available from various sources to improve the usefulness and functionality of devices such as mobile phones. The present disclosure contemplates that in some instances, this gathered data may include personal information data that uniquely identifies or can be used to contact or locate a specific person. Such personal information data can include demographic data, location-based data, telephone numbers, email addresses, twitter ID&#39;s, home addresses, data or records relating to a user&#39;s health or level of fitness (e.g., vital signs measurements, medication information, exercise information), date of birth, or any other identifying or personal information. 
     The present disclosure recognizes that the use of such personal information data, in the present technology, can be used to the benefit of users. For example, the personal information data can be used to locate devices, deliver targeted content that is of greater interest to the user, or the like. Further, other uses for personal information data that benefit the user are also contemplated by the present disclosure. For instance, health and fitness data may be used to provide insights into a user&#39;s general wellness, or may be used as positive feedback to individuals using technology to pursue wellness goals. 
     The present disclosure contemplates that the entities responsible for the collection, analysis, disclosure, transfer, storage, or other use of such personal information data will comply with well-established privacy policies and/or privacy practices. In particular, such entities should implement and consistently use privacy policies and practices that are generally recognized as meeting or exceeding industry or governmental requirements for maintaining personal information data private and secure. Such policies should be easily accessible by users, and should be updated as the collection and/or use of data changes. Personal information from users should be collected for legitimate and reasonable uses of the entity and not shared or sold outside of those legitimate uses. Further, such collection/sharing should occur after receiving the informed consent of the users. Additionally, such entities should consider taking any needed steps for safeguarding and securing access to such personal information data and ensuring that others with access to the personal information data adhere to their privacy policies and procedures. Further, such entities can subject themselves to evaluation by third parties to certify their adherence to widely accepted privacy policies and practices. In addition, policies and practices should be adapted for the particular types of personal information data being collected and/or accessed and adapted to applicable laws and standards, including jurisdiction-specific considerations. For instance, in the US, collection of or access to certain health data may be governed by federal and/or state laws, such as the Health Insurance Portability and Accountability Act (HIPAA); whereas health data in other countries may be subject to other regulations and policies and should be handled accordingly. Hence different privacy practices should be maintained for different personal data types in each country. 
     Despite the foregoing, the present disclosure also contemplates embodiments in which users selectively block the use of, or access to, personal information data. That is, the present disclosure contemplates that hardware and/or software elements can be provided to prevent or block access to such personal information data. For example, in the case of advertisement delivery services, the present technology can be configured to allow users to select to “opt in” or “opt out” of participation in the collection of personal information data during registration for services or anytime thereafter. In addition to providing “opt in” and “opt out” options, the present disclosure contemplates providing notifications relating to the access or use of personal information. For instance, a user may be notified upon downloading an app that their personal information data will be accessed and then reminded again just before personal information data is accessed by the app. 
     Moreover, it is the intent of the present disclosure that personal information data should be managed and handled in a way to minimize risks of unintentional or unauthorized access or use. Risk can be minimized by limiting the collection of data and deleting data once it is no longer needed. In addition, and when applicable, including in certain health related applications, data de-identification can be used to protect a user&#39;s privacy. De-identification may be facilitated, when appropriate, by removing specific identifiers (e.g., date of birth, etc.), controlling the amount or specificity of data stored (e.g., collecting location data at a city level rather than at an address level), controlling how data is stored (e.g., aggregating data across users), and/or other methods. 
     Therefore, although the present disclosure broadly covers use of personal information data to implement one or more various disclosed embodiments, the present disclosure also contemplates that the various embodiments can also be implemented without the need for accessing such personal information data. That is, the various embodiments of the present technology are not rendered inoperable due to the lack of all or a portion of such personal information data. For example, content can be selected and delivered to users by inferring preferences based on non-personal information data or a bare minimum amount of personal information, such as the content being requested by the device associated with a user, other non-personal information available to the content delivery services, or publicly available information. 
     The foregoing description, for purposes of explanation, used specific nomenclature to provide a thorough understanding of the described embodiments. However, it will be apparent to one skilled in the art that the specific details are not required in order to practice the described embodiments. Thus, the foregoing descriptions of the specific embodiments described herein are presented for purposes of illustration and description. They are not targeted to be exhaustive or to limit the embodiments to the precise forms disclosed. It will be apparent to one of ordinary skill in the art that many modifications and variations are possible in view of the above teachings. Also, when used herein to refer to positions of components, the terms above, below, over, under, left, or right (or other similar relative position terms), do not necessarily refer to an absolute position relative to an external reference, but instead refer to the relative position of components within the figure being referred to. Similarly, horizontal and vertical orientations may be understood as relative to the orientation of the components within the figure being referred to, unless an absolute horizontal or vertical orientation is indicated.