PATENT DOCUMENT

Publication Number: US-9954273-B2
Application Number: US-201514676424-A
Country: US
Kind Code: B2

Title: Electronic device antennas with laser-activated plastic and foam carriers

Abstract:
An electronic device may be provided with wireless circuitry that includes antennas. An antenna may be formed from metal traces on a dielectric antenna carrier. The antenna carrier may be formed by molding a layer of plastic onto the surface of a foam member. The foam member may have a low dielectric constant to enhance antenna performance and may be formed from a stiff closed cell plastic foam material. Heat and pressure may be used to attach the layer of plastic to the surface of the foam member without adhesive. A laser may be used to selectively expose portions of the plastic layer to laser light. The plastic layer may include additives that sensitize the plastic layer to light exposure. Electroplated metal traces for the antenna may be formed on the exposed portions of the plastic layer while leaving other portions of the plastic layer uncovered with metal.

Claims:
What is claimed is: 
     
       1. An antenna, comprising:
 a foam member; 
 a layer of plastic attached to the foam member, wherein the layer of plastic includes a light-sensitive additive; 
 a metal trace on a laser-activated area of the layer of plastic, wherein the laser-activated area includes a light-activated portion of the light-sensitive additive; and 
 a transmission line that includes a signal path and a portion of the foam member that surrounds the signal path. 
 
     
     
       2. The antenna defined in  claim 1  wherein the layer of plastic is laminated to the foam member without adhesive. 
     
     
       3. The antenna defined in  claim 2  wherein the layer of plastic has a thickness of less than 0.5 mm. 
     
     
       4. The antenna defined in  claim 1  wherein the foam member comprises a closed cell acrylic foam. 
     
     
       5. The antenna defined in  claim 4  wherein the foam member has a dielectric constant of less than 1.25. 
     
     
       6. The antenna defined in  claim 5  wherein the metal trace includes a resonating element and an antenna ground. 
     
     
       7. The antenna defined in  claim 6  wherein the resonating element is formed on a first surface of the foam member and the antenna ground is formed on a second surface of the foam member. 
     
     
       8. The antenna defined in  claim 7  wherein the first and second surfaces of the foam member are planar surfaces. 
     
     
       9. The antenna defined in  claim 1  wherein the foam member is a hollow foam member. 
     
     
       10. The antenna defined in  claim 1  wherein a portion of the foam member is uncovered by the plastic layer. 
     
     
       11. The antenna defined in  claim 10  wherein the foam member has a plurality of recesses and wherein the metal trace extends over the recesses. 
     
     
       12. The antenna defined in  claim 1  wherein the foam member has at least one curved surface. 
     
     
       13. The antenna defined in  claim 1  wherein the layer of plastic directly contacts the foam member. 
     
     
       14. An electronic device, comprising:
 radio-frequency transceiver circuitry; 
 an antenna formed from an electroplated metal trace on a laser-activated area on a plastic layer that is attached to a planar surface of a foam member without adhesive and molded to a shape of the foam member along at least the planar surface and an additional surface of the foam member adjacent to the planar surface, wherein the laser-activated area on the plastic layer is sensitized for formation of the electroplated metal trace on the laser-activated area; and 
 a transmission line coupled between the radio-frequency transceiver circuitry and the antenna. 
 
     
     
       15. The electronic device defined in  claim 14  wherein the foam member has a first portion that serves as a support for the antenna and has a second portion that extends from the first portion and forms part of the transmission line. 
     
     
       16. The electronic device defined in  claim 15  wherein the transmission line includes an inner conductor that is surrounded by the second portion of the foam member. 
     
     
       17. The electronic device defined in  claim 14  further comprising solder that attaches a metal structure in the transmission line to the electroplated metal trace. 
     
     
       18. The electronic device defined in  claim 14  wherein the additional surface comprises an additional planar surface and the planar surface is perpendicular to the additional planar surface. 
     
     
       19. The electronic device defined in  claim 14  wherein the planar surface is a first surface of the foam member, the additional surface is a second surface of the foam member, the foam member includes a third surface, the first and second surfaces are non-coplanar, the first and third surfaces are non-coplanar, and the plastic layer molded to the shape of the foam member along the first, second, and third surfaces of the foam member. 
     
     
       20. An electronic device, comprising:
 radio-frequency transceiver circuitry; 
 an antenna formed from an electroplated metal trace on a laser-activated area on a plastic layer that is attached to a foam member without adhesive; and 
 a transmission line coupled between the radio-frequency transceiver circuitry and the antenna, wherein the foam member has a first portion that serves as a support for the antenna and has a second portion that extends from the first portion and forms part of the transmission line and wherein the transmission line includes an inner conductor that is surrounded by the second portion of the foam member.

Description:
BACKGROUND 
     This relates generally to electronic devices and, more particularly, to electronic devices with antennas. 
     Electronic devices often include antennas. For example, cellular telephones, computers, and other devices often contain antennas for supporting wireless communications. 
     It can be challenging to form electronic device antenna structures with desired attributes. In some wireless devices, the presence of conductive housing structures can influence antenna performance. Antenna performance may not be satisfactory if the housing structures are not configured properly and interfere with antenna operation. Device size can also affect performance. It can be difficult to achieve desired performance levels in a compact device, particularly when the compact device has conductive housing structures. 
     It would therefore be desirable to be able to provide improved antennas for electronic devices. 
     SUMMARY 
     An electronic device may be provided with wireless circuitry that includes antennas. An antenna may be formed from metal traces on a dielectric antenna carrier. The antenna carrier may be formed by molding a layer of plastic onto the surface of a foam member. The foam member may have a low dielectric constant to enhance antenna performance and may be formed from a stiff closed cell plastic foam material. 
     Heat and pressure may be used to attach the layer of plastic to the surface of the foam member without adhesive. A laser may be used to selectively expose portions of the plastic layer to laser light. The plastic layer may include additives that sensitize the plastic layer to light exposure. Electroplated metal traces for the antenna may be formed on the exposed portions of the plastic layer while leaving other portions of the plastic layer uncovered with metal. 
     The foam member may be molded into a shape that forms a housing frame, a display chassis, or other structural member in an electronic device. Cables and other structures may pass through interior cavities in the foam member. The foam member may be molded into a shape with undulations or other recesses. Antenna size may be minimized in configurations in which the metal traces run over the undulations. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an illustrative electronic device with wireless communications circuitry in accordance with an embodiment. 
         FIG. 2  is a schematic diagram of an illustrative electronic device with wireless communications circuitry in accordance with an embodiment. 
         FIG. 3  is a diagram of illustrative wireless circuitry in accordance with an embodiment. 
         FIG. 4  is a perspective view of an illustrative antenna formed on a foam carrier covered with a plastic sheet in accordance with an embodiment. 
         FIG. 5  is cross-sectional side view of an illustrative antenna formed on a foam carrier covered with a plastic sheet in accordance with an embodiment. 
         FIG. 6  is a diagram of illustrative equipment and operations involved in forming an antenna in accordance with an embodiment. 
         FIG. 7  is a cross-sectional side view of an illustrative molding tool that is being used to form a foam antenna carrier in accordance with an embodiment. 
         FIG. 8  is a cross-sectional side view of an illustrative antenna carrier formed using a molding tool of the type shown in  FIG. 7  in accordance with an embodiment. 
         FIG. 9  is a cross-sectional side view of an illustrative antenna formed on a carrier having multiple dielectric layers attached to the surface of a foam structure in accordance with an embodiment. 
         FIG. 10  is a cross-sectional side view of an illustrative antenna carrier having a sheet of plastic that has been molded around the upper and lower surfaces of a foam structure in accordance with an embodiment. 
         FIG. 11  is a perspective view of an illustrative antenna formed from a foam carrier that has an integrated transmission line portion in accordance with an embodiment. 
         FIG. 12  is a perspective view of another illustrative antenna formed from a foam carrier that has an integrated transmission line portion in accordance with an embodiment. 
         FIG. 13  is a cross-sectional side view of an illustrative antenna formed on a foam member with a plastic layer in which metal traces on the plastic layer have been soldered to conductors in a transmission line in accordance with an embodiment. 
         FIG. 14  is a diagram of illustrative operations involved in forming a transmission line or antenna with an embedded conductive line in accordance with an embodiment. 
         FIG. 15  is a cross-sectional side view of an illustrative molded foam structure for an antenna having grooves or other recesses in accordance with an embodiment. 
         FIG. 16  is a perspective view of an illustrative foam housing frame with a portion that has been covered with a sheet of plastic and electroplated metal traces on laser-exposed portions of the sheet of plastic to form an antenna in accordance with an embodiment. 
         FIG. 17  is a cross-sectional side view of an illustrative hollow antenna structure in accordance with an embodiment. 
         FIG. 18  is a perspective view of an illustrative molded foam structure for an antenna having grooves that form undulations and metal antenna traces that run perpendicular to the grooves in accordance with an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     An electronic device such as electronic device  10  of  FIG. 1  may contain wireless circuitry. The wireless circuitry may include antenna structures such as antennas with metal traces supported by dielectric antenna carriers. The antenna carriers may have foam covered with a layer of plastic. The plastic may be a sheet of plastic that is suitable for selective laser activation. Following exposure to laser light in selected areas, metal traces can be formed on the exposed areas of the plastic layer using electroplating techniques (i.e., electroless plating). 
     Electronic device  10  may be a computing device such as a laptop computer, a computer monitor containing an embedded computer, a tablet computer, a cellular telephone, a media player, or other handheld or portable electronic device, a smaller device such as a wrist-watch device, a pendant device, a headphone or earpiece device, a device embedded in eyeglasses or other equipment worn on a user&#39;s head, or other wearable or miniature device, a television, a computer display that does not contain an embedded computer, a gaming device, a navigation device, an embedded system such as a system in which electronic equipment with a display is mounted in a kiosk or automobile, equipment that implements the functionality of two or more of these devices, or other electronic equipment. In the illustrative configuration of  FIG. 1 , device  10  is a portable device such as a cellular telephone, media player, tablet computer, or other portable computing device. Other configurations may be used for device  10  if desired. The example of  FIG. 1  is merely illustrative. 
     In the example of  FIG. 1 , device  10  includes a display such as display  14 . Display  14  has been mounted in a housing such as housing  12 . Housing  12 , which may sometimes be referred to as an enclosure or case, may be formed of plastic, glass, ceramics, fiber composites, metal (e.g., stainless steel, aluminum, etc.), other suitable materials, or a combination of any two or more of these materials. Housing  12  may be formed using a unibody configuration in which some or all of housing  12  is machined or molded as a single structure or may be formed using multiple structures (e.g., an internal frame structure, one or more structures that form exterior housing surfaces, etc.). 
     Display  14  may be a touch screen display that incorporates a layer of conductive capacitive touch sensor electrodes or other touch sensor components (e.g., resistive touch sensor components, acoustic touch sensor components, force-based touch sensor components, light-based touch sensor components, etc.) or may be a display that is not touch-sensitive. Capacitive touch screen electrodes may be formed from an array of indium tin oxide pads or other transparent conductive structures. 
     Display  14  may include an array of pixels formed from liquid crystal display (LCD) components, an array of electrophoretic pixels, an array of plasma pixels, an array of organic light-emitting diode pixels, an array of electrowetting pixels, or pixels based on other display technologies. 
     Display  14  may be protected using a display cover layer such as a layer of transparent glass or clear plastic. Openings may be formed in the display cover layer. For example, an opening may be formed in the display cover layer to accommodate a button such as button  16 . An opening may also be formed in the display cover layer to accommodate ports such as a speaker port. Openings may be formed in housing  12  to form communications ports (e.g., an audio jack port, a digital data port, etc.). Openings in housing  12  may also be formed for audio components such as a speaker and/or a microphone. 
     Antennas may be mounted in housing  12 . For example, housing  12  may have four peripheral edges as shown in  FIG. 1  and one or more antennas  40  may be mounted along the edges of housing  12 , at the corners of housing  12  (as shown in  FIG. 1 ) or elsewhere in device  10 . Antennas  40  may be mounted under dielectric antenna windows in a metal housing, under portions of display  14 , within a plastic device housing, or at other suitable locations within device  10 . There may be any suitable number of antennas  40  in device  10  (e.g., one antenna, two antennas, three antennas, or four or more antennas). 
     A schematic diagram showing illustrative components that may be used in device  10  is shown in  FIG. 2 . As shown in  FIG. 2 , device  10  may include control circuitry such as storage and processing circuitry  30 . Storage and processing circuitry  30  may include storage such as hard disk drive storage, nonvolatile memory (e.g., flash memory or other electrically-programmable-read-only memory configured to form a solid state drive), volatile memory (e.g., static or dynamic random-access-memory), etc. Processing circuitry in storage and processing circuitry  30  may be used to control the operation of device  10 . This processing circuitry may be based on one or more microprocessors, microcontrollers, digital signal processors, baseband processor integrated circuits, application specific integrated circuits, etc. 
     Storage and processing circuitry  30  may be used to run software on device  10 , such as internet browsing applications, voice-over-internet-protocol (VOIP) telephone call applications, email applications, media playback applications, operating system functions, etc. To support interactions with external equipment, storage and processing circuitry  30  may be used in implementing communications protocols. Communications protocols that may be implemented using storage and processing circuitry  30  include internet protocols, wireless local area network protocols (e.g., IEEE 802.11 protocols—sometimes referred to as WiFi®), protocols for other short-range wireless communications links such as the Bluetooth® protocol, cellular telephone protocols, MIMO protocols, antenna diversity protocols, satellite navigation system protocols, etc. 
     Device  10  may include input-output circuitry  44 . Input-output circuitry  44  may include input-output devices  32 . Input-output devices  32  may be used to allow data to be supplied to device  10  and to allow data to be provided from device  10  to external devices. Input-output devices  32  may include user interface devices, data port devices, and other input-output components. For example, input-output devices may include touch screens, displays without touch sensor capabilities, buttons, joysticks, scrolling wheels, touch pads, key pads, keyboards, microphones, cameras, speakers, status indicators, light sources, audio jacks and other audio port components, digital data port devices, light sensors, accelerometers or other components that can detect motion and device orientation relative to the Earth, capacitance sensors, proximity sensors (e.g., a capacitive proximity sensor and/or an infrared proximity sensor), magnetic sensors, a connector port sensor or other sensor that determines whether device  10  is mounted in a dock, and other sensors and input-output components. 
     Input-output circuitry  44  may include wireless communications circuitry  34  for communicating wirelessly with external equipment. Wireless communications circuitry  34  may include radio-frequency (RF) transceiver circuitry formed from one or more integrated circuits, power amplifier circuitry, low-noise input amplifiers, passive RF components, one or more antennas  40 , transmission lines, and other circuitry for handling RF wireless signals. Wireless signals can also be sent using light (e.g., using infrared communications). 
     Wireless communications circuitry  34  may include radio-frequency transceiver circuitry  90  for handling various radio-frequency communications bands. For example, circuitry  34  may include transceiver circuitry  36 ,  38 , and  42 . 
     Transceiver circuitry  36  may be wireless local area network transceiver circuitry that may handle 2.4 GHz and 5 GHz bands for WiFi® (IEEE 802.11) communications and that may handle the 2.4 GHz Bluetooth® communications band. 
     Circuitry  34  may use cellular telephone transceiver circuitry  38  for handling wireless communications in frequency ranges such as a low communications band from 700 to 960 MHz, a midband from 1710 to 2170 MHz, and a high band from 2300 to 2700 MHz or other communications bands between 700 MHz and 2700 MHz or other suitable frequencies (as examples). Circuitry  38  may handle voice data and non-voice data. 
     Wireless communications circuitry  34  can include circuitry for other short-range and long-range wireless links if desired. For example, wireless communications circuitry  34  may include 60 GHz transceiver circuitry, circuitry for receiving television and radio signals, paging system transceivers, near field communications (NFC) circuitry, etc. 
     Wireless communications circuitry  34  may include satellite navigation system circuitry such as global positioning system (GPS) receiver circuitry  42  for receiving GPS signals at 1575 MHz or for handling other satellite positioning data (e.g., GLONASS signals at 1609 MHz). In WiFi® and Bluetooth® links and other short-range wireless links, wireless signals are typically used to convey data over tens or hundreds of feet. In cellular telephone links and other long-range links, wireless signals are typically used to convey data over thousands of feet or miles. 
     Antennas  40  in wireless communications circuitry  34  may be formed using any suitable antenna types. For example, antennas  40  may include antennas with resonating elements that are formed from loop antenna structures, patch antenna structures, inverted-F antenna structures, slot antenna structures, planar inverted-F antenna structures, helical antenna structures, hybrids of these designs, etc. If desired, one or more of antennas  40  may be cavity-backed antennas formed by placing slot antennas, monopole antennas, and other resonating element structures over the opening in a metal antenna cavity. Different types of antennas may be used for different bands and combinations of bands. For example, one type of antenna may be used in forming a local wireless link antenna and another type of antenna may be used in forming a remote wireless link antenna. Dedicated antennas may be used for receiving satellite navigation system signals or, if desired, antennas  40  can be configured to receive both satellite navigation system signals and signals for other communications bands (e.g., wireless local area network signals and/or cellular telephone signals). 
     Transmission line paths may be used to couple antenna structures  40  to transceiver circuitry  90 . Transmission lines in device  10  may include coaxial cable paths, microstrip transmission lines, stripline transmission lines, edge-coupled microstrip transmission lines, edge-coupled stripline transmission lines, transmission lines formed from combinations of transmission lines of these types, etc. Filter circuitry, switching circuitry, impedance matching circuitry, and other circuitry may be interposed within the transmission lines, if desired. 
     Device  10  may contain multiple antennas  40 . The antennas may be used together or one of the antennas may be switched into use while the other antenna(s) may be switched out of use. If desired, control circuitry  30  may be used to select an optimum antenna to use in device  10  in real time and/or an optimum setting for a phase shifter or other wireless circuitry coupled to the antennas (e.g., an optimum antenna to receive satellite navigation system signals, etc.). Control circuitry  30  may, for example, make an antenna selection or antenna array phase adjustment based on information on received signal strength, based on sensor data (e.g., orientation information from an accelerometer), based on other sensor information (e.g., information indicating whether device  10  has been mounted in a dock in a portrait orientation), or based on other information about the operation of device  10 . 
     As shown in  FIG. 3 , transceiver circuitry  90  in wireless circuitry  34  may be coupled to antenna structures  40  using paths such as transmission line path  92 . Wireless circuitry  34  may be coupled to control circuitry  30 . Control circuitry  30  may be coupled to input-output devices  32 . Input-output devices  32  may supply output from device  10  and may receive input from sources that are external to device  10 . 
     To provide antenna structures  40  with the ability to cover communications frequencies of interest, antenna structures  40  may be provided with circuitry such as filter circuitry (e.g., one or more passive filters and/or one or more tunable filter circuits). Discrete components such as capacitors, inductors, and resistors may be incorporated into the filter circuitry. Capacitive structures, inductive structures, and resistive structures may also be formed from patterned metal structures (e.g., part of an antenna). If desired, antenna structures  40  may be provided with adjustable circuits such as tunable components  102  to tune antennas over communications bands of interest. Tunable components  102  may include tunable inductors, tunable capacitors, or other tunable components. Tunable components such as these may be based on switches and networks of fixed components, distributed metal structures that produce associated distributed capacitances and inductances, variable solid state devices for producing variable capacitance and inductance values, tunable filters, or other suitable tunable structures. During operation of device  10 , control circuitry  30  may issue control signals on one or more paths such as path  88  that adjust inductance values, capacitance values, or other parameters associated with tunable components  102 , thereby tuning antenna structures  40  to cover desired communications bands. Configurations in which antennas  40  are fixed (not tunable) may also be used. 
     Path  92  may include one or more transmission lines. As an example, signal path  92  of  FIG. 3  may be a transmission line having a positive signal conductor such as line  94  and a ground signal conductor such as line  96 . Lines  94  and  96  may form parts of a coaxial cable or a microstrip transmission line on a printed circuit (as examples). A matching network formed from components such as inductors, resistors, and capacitors may be used in matching the impedance of antenna structures  40  to the impedance of transmission line  92 . Matching network components may be provided as discrete components (e.g., surface mount technology components) or may be formed from housing structures, printed circuit board structures, traces on plastic supports, etc. Components such as these may also be used in forming filter circuitry in antenna structures  40 . 
     Transmission line  92  may be coupled to antenna feed structures associated with antenna structures  40 . As an example, antenna structures  40  may form an inverted-F antenna, a slot antenna, a hybrid inverted-F slot antenna, a monopole antenna, an antenna having a parasitic antenna resonating element, or other antenna having an antenna feed with a positive antenna feed terminal such as terminal  98  and a ground antenna feed terminal such as ground antenna feed terminal  100 . Positive transmission line conductor  94  may be coupled to positive antenna feed terminal  98  and ground transmission line conductor  96  may be coupled to ground antenna feed terminal  92 . Other types of antenna feed arrangements may be used if desired. The illustrative feeding configuration of  FIG. 3  is merely illustrative. 
     It may be desirable to form one or more of antennas  40  using foam carriers. The foam in a foam antenna carrier may be formed from a dielectric material that has a low dielectric constant (e.g., a polymer foam material such as a plastic that incorporates air bubbles or other voids), thereby enhancing antenna performance. The dielectric constant of the foam may be, for example, less than 1.4, less than 1.3, less than 1.25, 1.05-1.25, less than 1.2, 1.1-1.2, more than 1.05, or any other suitable value. 
     A perspective view of an illustrative antenna formed using a foam antenna carrier is shown in  FIG. 4 . As shown in  FIG. 4 , antenna  40  may be supported by an elongated foam core structure such as foam member  120 . Foam member  120  may be formed from a stiff acrylic closed cell foam with a high temperature resistance (e.g., an ability to withstand damage at an applied temperature of 220° C. or more, 200° C. or more, etc.) such as the Rohacell® foam available from Evonik industries of Essen, Germany. Other plastic foams may be used if desired. 
     Stiff foam is desirable for foam  120  because it helps antenna  40  hold its shape during use in device  10  so that the performance of antenna  40  is stable. High temperature resistance in foam  120  allows cables, metal structures in flexible printed circuits, and other conductive transmission line structures or signal lines to be mounted to antenna  40  using solder (e.g., a solder reflow process, hot-bar soldering techniques, etc.). Low dielectric constant foams help enhance antenna performance by minimizing power loss. If desired, foam structure  120  may be formed from a flexible foam, a low temperature foam, etc. The use of a stiff high temperature foam with a low dielectric constant is merely illustrative. 
     Antenna  40  may include metal structures such as metal traces  124  for forming an antenna resonating element such as antenna resonating element  124 - 2  and antenna ground  124 - 1 . Metal structures such as traces  124  may be formed directly on foam  120  or traces  124  may be formed on a layer of dielectric such as dielectric layer  122  that is attached to the some or all of the surfaces of foam  120 . 
     With one suitable arrangement, layer  122  is a layer of laser direct structuring (LDS) plastic and metal traces  124  are formed using laser direct structuring (LDS) techniques. With laser direct structuring techniques, a metal complex or other additive may be incorporated into the plastic material that forms plastic layer  122  to ensure that plastic layer  122  can be activated by light exposure. Plastic layer  122  may be formed from a plastic material such as polycarbonate (PC), acrylonitrile butadiene styrene (ABS), a PC/ABS blend, or other plastics (as examples). Upon exposure to laser light in particular areas, the exposed areas of the surface of layer  122  become sensitized for subsequent metal growth (e.g., metal growth during metal electroplating using electroless deposition techniques). During metal growth operations following selective surface activation with laser light, electroplated metal  124  (i.e., electrolessly deposited metal) will grow only in the activated areas exposed to the laser light. The thickness of plastic  122  may be about 0.1-1 mm, less than 0.8 mm, less than 0.6 mm, less than 0.5 mm, less than 0.3 mm, less than 0.2 mm, more than 0.05 mm, more than 0.1 mm, 0.1-0.5 mm, 0.05-0.5 mm, or other suitable thickness. The dielectric constant of layer  122  may be about 2.7-3, may be less than 3.5, may be more than 2, may be 1.8-3.1, or may have any other suitable value. Layer  122  may be attached to layer  120  using lamination techniques (e.g., application of heat and pressure in a mold), adhesive, or other suitable techniques. 
     The addition of LDS plastic layer  122  onto the surface of foam structure  120  facilitates the formation of laser-patterned metal traces  124  for antenna  40  on the surface of the dielectric carrier formed from foam  120  and plastic layer  122 . By using laser direct structuring to pattern metal onto the surface of layer  122  and foam to form a supporting core structure such as structure  120 , the antenna carrier for antenna  40  may incorporate potentially complex shapes. As an example, foam  120  and layer  122  may form shapes that are hollow, may include grooves or other recesses, may have bends, may have planar surfaces and/or curved surfaces, or may have other suitable shapes. 
     In the illustrative configuration of  FIG. 4 , foam  120  has an elongated shape with a curved surface that supports trace  124 - 2  and a planar surface that supports trace  124 - 1 . This is merely an example. Foam  120  and plastic layer  122  may have any suitable shape and metal traces  124  for antenna  40  may have any suitable shape. Moreover, additional conductive structures (e.g., portions of housing  12 , etc.) may, if desired, form portions of antenna  40  (e.g., portions of an antenna ground, portions of a resonating element, etc.). 
       FIG. 5  is a cross-sectional side view of an illustrative antenna formed using foam  120 , LDS plastic layer  122 , and electroplated metal traces  124  formed on laser-activated areas of layer  122 . As shown in  FIG. 5 , foam  120  may include plastic material  126  that is filled with voids  128  (e.g., air-filled holes, bubbles of gasses other than air, etc.). 
     Illustrative equipment and fabrication techniques of the type that may be used in forming antenna  40  are shown in  FIG. 6 . As shown in  FIG. 6 , molding tool  130  may be used to laminate plastic layer  122  to the outer surface of foam  120 . Molding tool  130  may include a heat source such as a lamp or heated metal die. When layer  122  is heated and compressed against foam  120  by molding tool  130 , layer  122  will become attached to foam  120  as shown in  FIG. 6 . The plastic of layer  122  will adhere to the plastic of foam structure  120  when heated and compressed without using any intervening adhesive, although a layer of adhesive may be used, if desired. Foam  120  may also be formed into a desired shape during the process of molding foam  120  and layer  122  with tool  130 . Metal traces  124  may be patterned onto layer  122  before or after molding layer  122  to foam  120 . In the illustrative arrangement of  FIG. 6 , laser patterning operations are performed after layer  122  has been attached to foam  120 . 
     As shown in  FIG. 6 , laser patterning tool  132  includes laser  136 . Laser  136  emits laser beam  138 . Laser  136  may be an infrared laser, a visible light laser, or an ultraviolet light laser. Laser  136  may be a pulsed laser or a continuous wave laser. The position of the laser light in beam  138  relative to the surface of plastic layer  122  may be controlled using computer-controlled laser positioner  134  and/or a positioner that adjusts the position of foam  120  and layer  122  relative to a stationary or moving laser. 
     After selectively exposing portions of the surface of layer  122  to laser light  138  such as illustrative exposed area  140  of  FIG. 6 , plating tool  142  may be used to selectively electroplate metal onto the surface of layer  120  in exposed area  140 , thereby forming laser-patterned metal traces  124  for antenna  40 . 
       FIG. 7  is a cross-sectional side view of an illustrative molding tool having an upper die such as die  130 - 1  and a lower die such as die  130 - 2 . Die  130 - 1  and die  130 - 2  may be heated to heat layer  122  and foam  120  during molding and/or heat may be applied to layer  122  and  120  using heat sources such as heat lamp  148 . When it is desired to mold layer  122  and foam  120  into a desired shape, die  130 - 1  may be moved in direction  144  and die  130 - 2  may be moved in direction  146 , thereby sandwiching layers  120  and  122  between die  130 - 1  and  130 - 2 . Using this type of process, desired antenna carrier shapes may be formed (see, e.g., illustrative antenna carrier  150  of  FIG. 8 ). 
     If desired, the outer surface of foam  120  may be covered with multiple layers of dielectric material. As shown in  FIG. 9 , for example, a structural layer such as layer  152  (e.g., a layer of carbon fiber material, other fiber-filled plastic materials, other plastics, dielectrics other than plastic, etc.) may be interposed between layer  122  and foam  120  to add additional strength to antenna  40  and/or to otherwise enhance the mechanical and electrical properties of antenna  40 . 
       FIG. 10  is a cross-sectional side view of an illustrative configuration for antenna  40  in which layer  122  has been used to cover the opposing upper and lower surfaces of foam  120  and the sides of foam  120  (e.g., so that layer  122  runs around the entire cross-sectional periphery of foam member  120 ). Metal traces  124  may be formed on the top, bottom, sides, or other surfaces of layer  122 . Structures of the type shown in  FIG. 10  may be formed by molding together upper and lower halves of foam  120  and corresponding plastic sheets  122 . If desired, the interior of foam  120  may be hollow (see, e.g., optional hollow portion  158 ). Hollow portion  158  may be formed by placing a portion of a molding tool within foam  120  during molding. The inclusion of hollow portion  158  may help reduce the effective dielectric constant of the antenna carrier. If desired, foam structure  120  may be formed from a pair of joined foam structures (e.g., foam that is joined along seam  156  before or after molding). 
       FIG. 11  shows how foam  120  (i.e., foam that underlies the exposed plastic of layer  122  in  FIG. 11 ), metal  124 , and layer  122  may be patterned to form a transmission line such as transmission line  92  that feeds an antenna such as antenna  40 . Antenna  40  and transmission line  92  may be formed from portions of the same foam and plastic carrier structure. Metal traces  124 - 1  may form an antenna ground in antenna  40  and metal traces  124 - 2  may form an antenna resonating element in antenna  40  (as an example). In transmission line  92 , portions of traces  124 - 2  may form positive signal path  94  and portions of traces  124 - 1  may form ground signal path  96 . 
     In the example of  FIG. 12 , transmission line structure portion  92 ′ of transmission line  92  has been formed from foam  120  that has been coated with plastic layer  122 . A metal trace on layer  122  (e.g., a laser-patterned metal trace) may be used in forming outer ground conductor  96  of transmission line portion  92 ′ Inner conductor  94  may be formed from a length of wire, metal traces on an embedded LDS plastic layer, patterned metal foil, or other metal. Portion  92 ′ may have a circular cross-sectional shape or other suitable shape. 
     If desired, a cable such as a coaxial cable or printed circuit that forms a transmission line may be soldered to antenna  40 . This type of arrangement is shown in the cross-sectional side view of antenna  40  and transmission line  92  of  FIG. 13 . As shown in  FIG. 13 , transmission line (printed circuit)  92  may include a substrate such as substrate  162  (e.g., a rigid printed circuit board substrate formed from a rigid printed circuit board material such as fiberglass-filled epoxy or a flexible printed circuit substrate formed from a flexible sheet of polyimide or other flexible layer of polymer). Positive signal traces and ground signal traces may be formed on substrate  162  (see, e.g., illustrative metal trace  160 ). Conductive transmission line structures such as metal trace  160  may be soldered to metal trace  124  in antenna  40  using solder  164 . If desired, electrical connections between the positive and ground traces of transmission line  92  may be formed with metal traces  124  on antenna  40  using conductive adhesive, welds, crimped connections, or other connections. 
       FIG. 14  shows how signal lines may be embedded within foam  120 . As shown in  FIG. 14 , LDS plastic layers  122 A and  122 B may be placed on the upper and lower surfaces of foam  120 A and molded under heat and pressure to form a planar upper surface layer  122 A and a curved lower surface layer  122 B. Metal trace  124 A (e.g., a positive signal line for a transmission line) may then be patterned on the top of layer  122 A and metal traces  124 B (e.g., part of a ground signal lines for a transmission line) may be patterned on layer  122 B using laser direct structuring techniques. Following patterning of metal traces  124 A and  124 B, foam layer  120 B, LDS plastic layer  122 C, and laser-patterned metal trace  124 C (e.g., another part of the ground signal path for the transmission line) may be formed on top of metal trace  124 A and layer  122 A. The completed structures of  FIG. 14  may be used to form a transmission line (e.g., transmission line  92 ) or other suitable structures (e.g., parts of antenna  40 , etc.). 
     As shown in the cross-sectional side view of  FIG. 15 , LDS plastic layers such as layers  122 ′ and  122 ″ and foam  120  may be provided with recesses  166  and this recessed antenna carrier structure may be provided with metal traces  124  to form antenna  40  (e.g., a cavity antenna or other antenna). 
     In the illustrative configuration of  FIG. 16 , foam  120  has been used to form rectangular structure  170 . Structure  170  may have a recess that receives structures  168 . Structures  168  may be layers of display  14  and structure  170  may be a display chassis or housing frame (as examples). Plastic layer  122  may be formed over a portion of foam  120  and laser-patterned metal traces  124  for antenna  40  may be formed on layer  122 . Portions of foam  120  may remain uncovered by layer  122 . There is one antenna in the configuration of  FIG. 16 , but multiple antennas may be formed from different segments of the rectangular foam ring structure formed from foam  120 , if desired. 
       FIG. 17  is a cross-sectional side view of an illustrative hollow foam structure (hollow foam  120 ) that has been coated with LDS plastic layer  122  and metal traces  124 . As shown in  FIG. 17 , structures  172  may pass through interior  174  of foam  120 . Foam  120  may be a hollow elongated member that extends into the page (in the orientation of  FIG. 17 ). Structures  172  may be electrical components, signal cables, or other elongated structures that extend along the length of foam  120  within elongated interior cavity  174 . A foam structure of the type shown in  FIG. 17  may, if desired, be used in forming a rectangular display chassis, housing frame, or other elongated member in device  10  (see, e.g., the rectangular structure of  FIG. 16 ). 
       FIG. 18  is a perspective view of an illustrative carrier formed from molded foam and LDS plastic layer  122  that has a series of recesses (grooves) such as recesses  176 . The presence of recesses  176  may help lengthen antenna trace  124  on the surface of plastic layer  122  without lengthening the distance L along axis Y between ends  178  of antenna trace  124 . By causing antenna trace  124  to undulate up and down in vertical dimension Z, the three-dimensional arrangement for antenna  40  of  FIG. 18  extends the length of trace  124  without increasing the footprint of foam  120  and thereby allows antenna  40  to be formed with a more compact layout than would otherwise be possible. 
     The foregoing is merely illustrative and various modifications can be made by those skilled in the art without departing from the scope and spirit of the described embodiments. The foregoing embodiments may be implemented individually or in any combination.

Metadata:
Filing Date: 20150401
Publication Date: 20180424
Grant Date: 20180424
Priority Date: 20150401
Inventors: SHIU, Boon W.
CHEN, CHUN-LUNG
IRCI, Erdinc
Assignee: APPLE INC
CPC Classifications: [{"code": "H01Q9/42", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/38", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01Q1/243", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/38", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01Q1/243", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q9/42", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 57015394