Patent Publication Number: US-9838599-B1

Title: Multiple camera alignment system with rigid substrates

Description:
BACKGROUND 
     Devices containing multiple cameras are increasingly being used. In computer vision applications, two cameras positioned side-by-side are used to capture stereo vision images. In panoramic camera systems, a series of cameras are positioned in a circular array such that the image frames captured by each camera can be combined so as to collectively capture a panoramic image as large as 360°. In these multiple-camera applications, the alignment between the cameras can be extremely important. Misalignment between cameras can result in a reduced field-of-view, incorrect distance measurements, and other errors resulting from the difference between the field-of-view captured by the misaligned camera and the expected field-of-view for the camera. 
     Accordingly, there is a need for improved designs and manufacturing processes for camera systems having multiple cameras. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a perspective view of a camera system, in accordance with embodiments of the present invention. 
         FIG. 2  is a block diagram showing an example architecture of a user device, such as the panoramic cameras, digital cameras, mobile devices and other computing devices described herein. 
         FIG. 3  is an exploded perspective view of a camera module with a substrate having guiding holes formed therein, in accordance with embodiments of the present invention. 
         FIG. 4  is a flowchart illustrating a method of manufacturing a camera modules, in accordance with embodiments of the present invention. 
         FIGS. 5A-5D  illustrate various steps in the manufacturing process illustrated in  FIG. 4 . 
         FIG. 6  is a perspective view of a camera system, in accordance with other embodiments of the present invention. 
         FIG. 7  is an exploded perspective view of a camera module with a lens module having guiding holes formed therein, in accordance with embodiments of the present invention. 
         FIG. 8  is a flowchart illustrating a method of manufacturing a camera modules, in accordance with embodiments of the present invention. 
         FIGS. 9A-9E  illustrate various steps in the manufacturing process illustrated in  FIG. 8 . 
         FIG. 10  is a perspective view of a camera system, in accordance with other embodiments of the present invention. 
         FIG. 11  is an exploded perspective view of the camera module shown in  FIG. 10 . 
         FIG. 12  is a flowchart illustrating a method of manufacturing a camera modules, in accordance with embodiments of the present invention. 
         FIGS. 13A-13E  illustrate various steps in the manufacturing process illustrated in  FIG. 2 . 
         FIG. 14  is a perspective view of a camera system, in accordance with other embodiments of the present invention. 
         FIG. 15  is an exploded perspective view of the camera module shown in  FIG. 14 . 
         FIG. 16  is a flowchart illustrating a method of manufacturing a camera modules, in accordance with embodiments of the present invention. 
         FIGS. 17A-17D  illustrate various steps in the manufacturing process illustrated in  FIG. 16 . 
     
    
    
     DETAILED DESCRIPTION 
     In the following description, reference is made to the accompanying drawings which illustrate several embodiments of the present disclosure. It is to be understood that other embodiments may be utilized, and system or process changes may be made without departing from the spirit and scope of the present disclosure. The following detailed description is not to be taken in a limiting sense, and the scope of the embodiments of the present invention is defined only by the claims of the issued patent. It is to be understood that the drawings are not necessarily drawn to scale. 
     Systems and methods in accordance with various embodiments of the present disclosure provide improved manufacturing methods and camera system designs that provide improved alignment between multiple camera modules mounted on a common chassis. The chassis includes a plurality of mounting regions, with each mounting region including one or more mounting posts. Each camera module includes one or more guiding holes into which the mounting posts are inserted. By precisely positioning the guiding holes and the mounting posts, the alignment of the camera modules with the chassis and the other camera modules may be controlled with high precision. 
     In some embodiments, the camera modules include a rigid silicon substrate onto which the image sensor die and other camera components are mounted. The guiding holes can be formed in the silicon substrate using chemical etching processes, similar to those used in semiconductor manufacturing. The chassis is provided with mounting regions to which the camera modules are to be attached. Each mounting region includes multiple mounting posts which are inserted into the etched guiding holes in the silicon substrate. The image sensor die may be surface mounted and wire bonded to corresponding contacts on the upper surface of the silicon substrate. The silicon substrate can be formed with a high degree of flatness (e.g., +/−1 μm), and the guiding holes may be etched into the substrate with high precision (e.g., with tolerances of +/−2 μm). As a result, the camera modules can be reliably positioned in the camera system with high precision. 
     In other embodiments, the camera modules include a lens module having a lens housing with a pair of flanges extending from the sides of the lens housing. Each flange includes one or more guiding holes into which the mounting posts of the chassis are inserted. The image sensor die may be flip-chip mounted to the lower surface of the silicon substrate. 
     In other embodiments, the camera modules include a flexible tape substrate coupled to a rigid stiffener member. The stiffener member provides structural support for the image sensor die and other electronic components of the camera module. One or more guiding holes may be formed in the stiffener member for coupling with corresponding mounting posts on the chassis. The image sensor die may be mounted to the stiffener member in an opening in the flexible tape substrate and wire bonded to corresponding contacts on the upper surface of the flexible tape substrate. 
     In other embodiments, the camera modules include flexible tape substrate coupled to a rigid stiffener member, and a lens module having a lens housing with a pair of flanges extending from the sides of the lens housing. Each flange includes one or more guiding holes into which the mounting posts of the chassis are inserted. The image sensor die may be flip-chip mounted to the lower surface of the flexible tape substrate. 
       FIG. 1  is a perspective view of a camera system  100  in accordance with embodiments of the present invention. This system  100  includes a rectangular chassis  102  having four sides onto which four digital camera modules  110   a - 110   d  are mounted. The four digital camera modules  110   a - 110   d  are positioned on the chassis  102  such that their respective optical axes are directed in orthogonal directions. Each camera module  110   a - 110   d  captures a greater than 90° field-of-view so that the image frames captured by each camera module  110   a - 110   d  contain overlapping fields-of-view that can be combined into a single panoramic frame capturing a 360° view around the chassis  102 . 
     Misalignment of camera modules in a multiple-camera system can cause a variety of problems, such as a reduced field-of-view, resulting in a less than 360° panoramic view. It is possible to compensate for some camera misalignment using sophisticated software calibration processes after the camera system is assembled, but these software calibration processes increase the total manufacturing time and may not be able to correct a significant misalignment in which there is a gap between the fields-of-view of adjacent cameras. In addition, jostling or dropping of the camera system after calibration can cause the camera modules to shift out of position again if they are not securely fixed to the chassis. It is also possible to compensate for some camera misalignment by using a higher megapixel image sensors than is necessary for the desired resolution. The larger field-of-view resulting from the higher resolution sensors can be used to compensate for slight misalignments of the cameras. This approach may be undesirable as it increases the cost of the image sensor to be used. It may also be possible to precisely position the camera modules onto the chassis using sophisticated alignment tools, such as a six-axis precision alignment system, for handling the camera modules. These alignment systems can be extremely expensive and may slow down the manufacturing process, thereby reducing the manufacturing units per hour (UPH). 
     In the system  100  shown in  FIG. 1 , each camera module  110  includes a rigid silicon substrate  120  having a pair of guiding holes  130  etched through the substrate  120 . When the camera modules  110   a - 110   d  are attached to the chassis  102 , precisely positioned mounting posts  140  on the chassis  102  are received in the guiding holes  130  to ensure that each camera module  110  is positioned precisely in the desired location. The guiding holes  130  and mounting posts  140  also serve to maintain the camera modules  110   a - 110   d  in their respective positions during handling and use after the manufacturing process is completed. 
       FIG. 2  is a block diagram showing an example architecture  200  of a camera system, such as the panoramic cameras, digital cameras, mobile devices and other computing devices described herein. It will be appreciated that not all camera systems will include all of the components of the architecture  200 , and some camera systems may include additional components not shown in the architecture  200 . The architecture  200  may include one or more processing elements  204  for executing instructions and retrieving data stored in a storage element  202 . The processing element  204  may comprise at least one processor. Any suitable processor or processors may be used. For example, the processing element  204  may comprise one or more digital signal processors (DSPs). The storage element  202  can include one or more different types of memory, data storage or computer readable storage media devoted to different purposes within the architecture  200 . For example, the storage element  202  may comprise flash memory, random access memory, disk-based storage, etc. Different portions of the storage element  202 , for example, may be used for program instructions for execution by the processing element  204 , storage of images or other digital works, and/or a removable storage for transferring data to other devices, etc. 
     The storage element  202  may also store software for execution by the processing element  204 . An operating system  222  may provide the user with an interface for operating the camera system and may facilitate communications and commands between applications executing on the architecture  200  and various hardware thereof. A transfer application  224  may be configured to receive video from another device (e.g., a panoramic camera or digital camera) or from an image sensor  232  included in the architecture  200 . In some examples, the transfer application  224  may also be configured to upload the received videos to another device that may perform compression as described herein (e.g., a mobile device, another computing device, or a remote image processor  52 ). In some examples, an image processor application  226  may perform compression on videos received from an image sensor of the architecture  200  and/or from another device. The image processor application  226  may be included, for example, at a panoramic camera, a digital camera, a mobile device or another computer system. In some examples, where compression is performed by a remote image processor system, the image processor application  226  may be omitted. A stitching utility  228  may stitch videos received from multiple image sensors into a single image and/or video. The stitching utility  228  may be included, for example, in a panoramic camera and/or a mobile device or other computing device receiving input from a panoramic camera. 
     When implemented in some camera systems, the architecture  200  may also comprise a display component  206 . The display component  206  may comprise one or more light emitting diodes (LEDs) or other suitable display lamps. Also, in some examples, the display component  206  may comprise, for example, one or more devices such as cathode ray tubes (CRTs), liquid crystal display (LCD) screens, gas plasma-based flat panel displays, LCD projectors, or other types of display devices, etc. 
     The architecture  200  may also include one or more input devices  208  operable to receive inputs from a user. The input devices  208  can include, for example, a push button, touch pad, touch screen, wheel, joystick, keyboard, mouse, trackball, keypad, light gun, game controller, or any other such device or element whereby a user can provide inputs to the architecture  200 . These input devices  208  may be incorporated into the architecture  200  or operably coupled to the architecture  200  via wired or wireless interface. When the display component  206  includes a touch sensitive display, the input devices  208  can include a touch sensor that operates in conjunction with the display component  206  to permit users to interact with the image displayed by the display component  206  using touch inputs (e.g., with a finger or stylus). The architecture  200  may also include a power supply  214 , such as a wired alternating current (AC) converter, a rechargeable battery operable to be recharged through conventional plug-in approaches, or through other approaches such as capacitive or inductive charging. 
     The architecture  200  may also include a communication interface  212 , comprising one or more wired or wireless components operable to communicate with one or more other camera systems and/or with the remote image processor system. For example, the communication interface  212  may comprise a wireless communication module  236  configured to communicate on a network according to any suitable wireless protocol, such as IEEE 802.11 or another suitable wireless local area network (WLAN) protocol. A short-range interface  234  may be configured to communicate using one or more short-range wireless protocols such as, for example, near field communications (NFC), Bluetooth™, Bluetooth LE™, etc. A mobile interface  240  may be configured to communicate utilizing a cellular or other mobile protocol. A Global Positioning System (GPS) module  238  may be in communication with one or more earth-orbiting satellites or other suitable position-determining systems to identify a position of the architecture  200 . A wired communication module  242  may be configured to communicate according to the Universal Serial Bus (USB) protocol or any other suitable protocol. 
     The architecture  200  may also include one or more sensors  230  such as, for example, one or more image sensors and one or more motion sensors. A single image sensor  232  is shown in  FIG. 2 , but multiple image sensors  232  may be used. For example, a panoramic camera may comprise multiple image sensors  232  resulting in multiple video frames that may be stitched to form a panoramic output. Motion sensors may include any sensors that sense motion of the architecture including, for example, gyro sensors  244  and accelerometers  246 . Motion sensors, in some examples, may be included in camera systems such as panoramic cameras, digital cameras, mobile devices, etc., that capture video to be compressed. The gyro sensor  244  may be configured to generate a signal indicating rotational motion and/or changes in orientation of the architecture (e.g., a magnitude and/or direction of the motion or change in orientation). Any suitable gyro sensor may be used including, for example, ring laser gyros, fiber-optic gyros, fluid gyros, vibration gyros, etc. The accelerometer  246  may generate a signal indicating an acceleration (e.g., a magnitude and/or direction of acceleration). Any suitable accelerometer may be used including, for example, a piezoresistive accelerometer, a capacitive accelerometer, etc. In some examples, the GPS interface  238  may be utilized as a motion sensor. For example, changes in the position of the architecture  200 , as determined by the GPS interface  238 , may indicate the motion of the GPS interface  238 . Other types of motion sensors that may be included in the architecture  200  include digital compass sensors, other location sensors (e.g., utilizing beacon signals or time stamps to determine a current or past location of the architecture), time-of-flight or other depth sensors, etc. In some examples, an image sensor may also be a motion sensor. For example, frames captured by an image sensor may be analyzed to determine a direction and magnitude of the camera&#39;s motion. 
       FIG. 3  is an exploded perspective view of a camera module  110  with a substrate having guiding holes formed therein, in accordance with embodiments of the present invention. 
     The camera module  110  comprises a silicon substrate  120 , an image sensor die  145 , a lens module  150 , and electronic components  135 . The lens module  150  comprises an autofocus lens housing  152  forming a cavity containing one or more lenses which are supported by a lens barrel  156 . The lens barrel  156  is driven by motors or actuators in the lens housing  152  to rotate, thereby translating the lens barrel  156  up and down along optical axis  148 . The lens module  150  may utilize voice coil motors (VCM) to move the lens barrel  156  along the optical axis of the camera. Alternatively, microelectromechanical systems (MEMS) actuators may be used to translate the lenses. A variety of lens modules, including a variety of multi-lens autofocus lens modules, are commercially available and may be utilized in accordance with various embodiments of the present invention. 
     The substrate  120  may comprise any form of circuit substrate suitable to provide the necessary structural support and interconnection structure for operation of the camera module  110 , as is well known in the art. In the illustrated embodiment, the substrate  120  comprises a silicon substrate, which may be manufactured using conventional semiconductor manufacturing processes to form the desired interconnect structure and diced to form individual substrates  120 . In other embodiments, the substrate  120  may be formed out of any suitable rigid material that possesses the desired level of flatness, such as, e.g., an Indium Tin Oxide (ITO) coated glass substrate. In accordance with some embodiments, the substrate  120  comprises an 8″ diameter silicon wafer having a flatness uniformity across its surface of +/−2 μm. Guiding holes  130   a - 130   b  may be formed in the substrate  120  using, for example, conventional lithography techniques to mask and etch the guiding holes  130   a - 130   b  through the substrate  120 . In other embodiments, the guiding holes  130   a - 130   b  may be formed in the substrate  120  using any suitable method of precisely forming the holes without resulting in cracking or other damage to the substrate  120 . 
     The upper side  121   a  of the substrate  120  includes a plurality of substrate-sensor contacts  129 . The image sensor die  145  includes a plurality of output die contacts  141  formed along one or more edges of the image sensor die  145 . The output die contacts  141  are coupled to the substrate-sensor contacts  129 , as will be described in greater detail below. 
     In the illustrated embodiment, the upper side  121   a  of the substrate  120  includes a plurality of component contacts  134  for coupling with the electronic components  135 . The electronic components  135  may include passive and/or active components for processing the output signals from the image sensor. The passive components may include inductors, capacitors, or resistors. The electronic components  135  are coupled to the component contacts  134  formed on the substrate  120 , thereby electrically coupling the electronic components  135  with the image sensor die  145  via the substrate-sensor contacts  129 . 
     The upper side  121   a  of the flexible substrate  120  further includes a main board contact region  344 . The main board contact region  344  can include a plurality of contacts  346 , which can be, for example, anisotropic conductive film (ACF) contacts or land grid array (LGA) pads which may be coupled to main board contacts on the main board of the camera system. The contacts  346  receive all of the power and I/O signals required for operation of the camera module  110 . The contacts  346  can be coupled to a flexible printed circuit (FPC), bonded (e.g., soldered) directly to corresponding contacts on the main board, coupled to an LGA socket mounted to the main board, or coupled to another intermediate interposer structure, such as a cable or circuit board, which is in turn coupled to the main board. 
     The image sensor die  145  includes a photosensor portion  144  comprising any type of image capturing element that converts an optical image into an electronic signal, such as, e.g., a charge-coupled device (CCD) or complementary metal-oxide-semiconductor (CMOS) active pixel sensor. 
     An optical filter (not shown) may be positioned above the image sensor die  145  to improve the quality of the images generated by the camera module. The optical filter may be used for filtering undesirable wavelengths of light, such as infrared light, received by the lens module  150  to prevent the light from reaching the photosensor portion  144  of the image sensor die  145 , which could degrade the quality of digital image generated. In other embodiments, other types of optical filters may be used, such as, for example, a blue or other color filter, or a polarizing filter. In some embodiments, the optical filter is incorporated into the lens module  150 . In other embodiments, a spacer member (not shown) may be coupled to the upper side  121   a  of the substrate  120  surrounding the image sensor die  145 . The spacer member can support the optical filter above the image sensor die  145  and bond wires  142  coupling the image sensor die  145  to the substrate  120 . 
       FIG. 4  is a flowchart illustrating a method  400  of manufacturing a camera system  100  with a rigid substrate  120  having guiding holes  130 , in accordance with embodiments of the present invention.  FIGS. 5A-5D  illustrate various steps in the manufacturing method  500 . 
     In step  401 , the image sensor die  145  is formed. Before each image sensor die  145  is singulated or diced from the wafer, a plurality of die contacts  141  are formed on the upper surface of each image sensor die  145 . The die contacts  141  can be formed in a variety of ways, depending on the desired method of coupling the image sensor die  145  to the substrate  120 . In the embodiment illustrated in  FIGS. 1, 3, and 5A-5D , the die contacts  141  on the image sensor die  145  may be used for wire bonding with the substrate  120 . The die contacts  141  may be formed using any of a variety of well-known techniques, such as, for example, using ball bonds. 
     In step  402 , a substrate  120  is provided. Before each substrate  120  is singulated or diced from the full silicon wafer, the interconnect structure is formed on the substrate  120 . Next, the guiding holes  130  are formed in the substrate  120 . As described above, the guiding holes  130  may be formed using conventional etching techniques or any other manufacturing process suitable to for precisely forming holes  130  in the substrate  120 . The topmost layer of the silicon substrate  120  may comprise, e.g., an aluminum nitride passivation layer. The various contacts on the upper surface  121   a  of the substrate  120  may be formed using, e.g., under bump metallogy (UBM), followed by an electroless nickel immersion gold (ENIG) plating. 
     Fiducial marks  124  may be formed on the upper surface  121   a  of the substrate  120  to facilitate machine vision alignment of the substrate  120  with the various components to be mounted to the substrate  120 . 
       FIG. 5A  illustrates an alternative embodiment of a substrate  120 ′ in which a die attach cavity  146  is formed on the upper surface  121   a ′ of the substrate  120 ′. The die attach cavity  146  is sized so as to permit the image sensor die  144  to be received in the cavity  146 . This brings the upper surface of the image sensor die  144  closer to or flush with the region of the upper surface  121   a ′ surrounding the cavity  146 . This reduces the height of the combined substrate  120 ′ and die  144 , which can enable a reduction in the overall height of the camera module  110 . The die attached cavity  146  can be formed by etching or any other desired process. 
     The upper side  121   a  of each substrate  120  further includes a plurality of component contacts  134  around the periphery of the image sensor opening  122 . In step  403 , the electronic components  135  may be coupled to each of these contacts  134  using, e.g., surface mount technology (SMT) processes. A plurality of lens module connections (not shown) may be provided along the outer edges of the substrate  120  for coupling with corresponding contacts (not shown) in the lens housing  152 . These lens module connections may be used to provide power, ground, and control signals to the lens module  150 . The various contacts provided on the substrate  120  may be formed, e.g., using ENIG plating techniques. In the embodiment shown in  FIG. 5B , six components  135  are shown. In other embodiments, greater or fewer components  135  may be used. 
     In step  404 , shown in  FIG. 5C , the image sensor die  145  is attached to the substrate  120 , using, for example, an epoxy adhesive. 
     In step  405 , the die contacts  141  on the upper surface of each image sensor die  145  are wire bonded to substrate-sensor contacts  129  on the upper surface of the flexible substrate  120 . Each of the die contacts  141  is coupled to a respective one of the substrate-sensor contacts  129  using a bond wire  142 , e.g., a gold bond wire. 
     In step  406 , shown in  FIG. 5D , the lens module  150  is coupled to the substrate  120 . The lens housing  152  of the lens module  150  may be attached to the substrate  120  by depositing an adhesive, such as an epoxy adhesive, onto a portion of the substrate  120  not otherwise used for electrical connections. A thermal curing step may then be used to cure the adhesive. The lens module connections (not shown) on the substrate  120  may then be coupled to the corresponding contacts (not shown) in the lens housing  152  using, for example, conventional soldering methods. 
     Any known technique may be used for positioning the lens module  150  onto the substrate  120 . Because the guiding holes  130  in the substrate  120  and the mounting posts  140  on the chassis enable precise positioning of the substrate  120  (and, as a result, the image sensor die  145 ) on the chassis  102 , it may not be necessary to utilize a high precision system for coupling the lens module  150  to the substrate  120 . Instead, a low-cost SMT pick-and-place system may be used to place the lens module  150  onto the substrate  120 . A downward-facing camera may be used to locate the center of the photosensor portion  144  of the image sensor die  145 , and an upward-facing camera may be used to locate the center of the lens barrel  156  so as to determine the location of the optical axis  148 . The SMT pick-and-place system may then use this location information to align the optical axis  148  with the center of the photosensor portion  144 . As a result, it may not be necessary to perform an active alignment step in which the camera is powered up and the optical characteristics of the lenses and image sensor die  145  measured, so that the positioning of the lens module  150  may be adjusted if it is not properly aligned. 
     In step  407 , each of the camera modules  110  are then coupled to the chassis  102 . The chassis  102  may be formed using any of a variety of materials and methods to achieve the desired structure. In one embodiment, the chassis  102  comprises an aluminum chassis body which is machined to form the mounting posts  140 . In other embodiments, holes may be formed in the chassis body and mounting posts  140  inserted into those holes. A thermal adhesive may be applied to the chassis body for coupling each of the substrates  120  to the chassis  102 . The thermal adhesive can help to dissipate heat generated by the image sensor dice  145  during operation of the camera system  100 . The heat can flow through the thermal adhesive to the aluminum chassis body away from the image sensor dice  145 . In the illustrated embodiment, the use of the relatively large chassis  102  to dissipate heat can help to draw the heat far from the image sensor dice  145 , thereby improving heat dissipation. Providing the camera system  100  with good thermal dissipation from the image sensor dice  145  can help reduce overheating of the image sensor dice  145 , and thereby improve image quality. A flex circuit or other connector can be used to connect the main board contact region  344  of the substrate  120  to the main board of the camera system  100 . The connector may be attached to the main board contact region  344  before or after the camera modules  110  are attached to the chassis  102 . 
     In the completed assembly shown in  FIG. 1 , four camera modules  110   a - 110   d  are used to provide a 360° field-of-view on a single plane. In other embodiments, greater or fewer camera modules may be provided in the camera system  100 , and the optical axes of the camera modules need not be co-planar. In some embodiments, an upward-facing camera module and a downward-facing camera module may be added to provide a complete panoramic image in all directions. 
     In addition, in the illustrated embodiment, the substrate  120  of each camera module  110  includes two guiding holes  130  positioned along opposing edges of the substrate  120 . In other embodiments, greater or fewer guiding holes  130 , e.g., one, two, three, or four holes may be used. 
       FIG. 6  is a perspective view of a camera system  600  in accordance with other embodiments of the present invention. This system  600  includes a rectangular chassis  602  having four sides onto which four digital camera modules  610   a - 610   d  are mounted. As with camera system  100  in  FIG. 1 , the four digital camera modules  610   a - 610   d  are positioned on the chassis  602  such that their respective optical axes are directed in orthogonal directions. 
       FIG. 7  is an exploded perspective view of a camera module  610  with a lens housing  652  having mounting features with guiding holes formed therein, in accordance with embodiments of the present invention. 
     In the system  600  shown in  FIGS. 6-7 , each camera module  610  includes a rigid silicon substrate  620  having a sensor opening  622  formed therein. The upper side  621   a  of the substrate  620  is coupled with the lens module  650  and the lower side  621   b  of the substrate  620  is coupled to the image sensor die  645  and electronic components  135 . The lower side  621   b  of the substrate  620  also includes a main board contact region  644  with a plurality of contacts  646 . The contacts  646  receive all of the power and I/O signals required for operation of the camera module  610 . The contacts  646  can be coupled to a flexible printed circuit (FPC), bonded (e.g., soldered) directly to corresponding contacts on the main board, coupled to an LGA socket mounted to the main board, or coupled to another intermediate interposer structure, such as a cable or circuit board, which is, in turn, coupled to the main board. 
     The lens module  650  comprises a lens housing  652 , which includes a pair of mounting features for aligning the camera modules  610  with the chassis  602 . In the embodiment illustrated in  FIGS. 6-7 , the mounting features comprise a pair of flanges  654  extending from opposite sides of the lens housing  652  and guiding holes  640   a - 640   d  formed in the flanges  654 . Like the lens module  150 , the lens module  650  comprises an autofocus lens housing  652  forming a cavity containing one or more lenses which are supported by a lens barrel  656 . 
     The chassis  602  comprises four camera support structures  603 , each structure  603  including platforms  604  onto which the flanges  654  are positioned. The platforms  604  include mounting posts  640 . When the camera modules  610   a - 610   d  are attached to the chassis  602 , precisely positioned mounting posts  640  on the chassis  602  are received in the guiding holes  630  to ensure that each camera module  610  is positioned precisely in the desired location. The guiding holes  630  and mounting posts  640  also serve to maintain the camera modules  610   a - 610   d  in their respective positions during handling and use after the manufacturing process is completed. In some embodiments, fasteners  642  may be used to provide adjustability to the positioning of the camera modules  610   a - 610   d . The fasteners  642  may be, e.g., screws received in threaded holes in the platforms  604  of the support structures  603 . When each camera module  610   a - 610   d  is first mounted onto the support structures  603  by inserting the mounting posts  640  in the guiding holes  630 , the fasteners  642  may be loosely screwed into their respective holes. The alignment of each camera module  610   a - 610   d  can then be tested (e.g., by powering on each camera module  610   a - 610   d  to inspect the images received by each module  610   a - 610   d ). If adjustments to the alignment of any module  610  is needed, the module  610  may be slightly shifted into the desired alignment and then the fasteners  642  tightened to securely retain the module  610  in the desired alignment. In the illustrated embodiment, each flange  654  includes two openings, a guiding hole  630  for receiving a mounting post  640  and a second hole for receiving a fastener  642 . In other embodiments, greater or fewer openings may be used. 
       FIG. 8  is a flowchart illustrating a method  800  of manufacturing a camera system  600  with a lens module  650  having guiding holes  630 , in accordance with embodiments of the present invention.  FIGS. 9A-9E  illustrate various steps in the manufacturing method  800 . 
     In step  801 , the image sensor die  645  is formed with a plurality of die contacts  641 . The die contacts  641  can be formed in a variety of ways, depending on the desired method of coupling the image sensor die  645  to the substrate  620 . In the embodiment illustrated in  FIGS. 6-7 , the image sensor die  645  is configured for flip-chip mounting to the substrate  620 , as will be described in more detail below. 
     In step  802 , a substrate  620  is provided.  FIG. 9A  is a perspective view of the bottom side  621   b  of the substrate  620 . The substrate  620  may comprise any form of circuit substrate suitable to provide the necessary structural support and interconnection structure for operation of the camera module  610 , as described above with respect to substrate  120 . 
     As with substrate  120 , before each substrate  620  is singulated or diced from the full silicon wafer, the interconnect structure is formed on the substrate  620 . However, in this embodiment, the guiding holes  630  are formed on the lens module  650  instead of the substrate  620 . Fiducial marks  624  may be formed on the lower surface  621   b  of the substrate  620  to facilitate machine vision alignment of the substrate  620  with the various components to be mounted to the substrate  620 . 
     The lower side  621   b  of each substrate  620  further includes a plurality of component contacts  634  around the periphery of the image sensor opening  622 . In step  803 , the electronic components  135  may be coupled to each of these contacts  634  using, e.g., surface mount technology (SMT) processes. A plurality of lens module connections (not shown) may be provided along the outer edges of the upper side  621   a  of the substrate  620  for coupling with corresponding contacts (not shown) in the lens housing  652 . These lens module connections may be used to provide power, ground, and control signals to the lens module  650 . The various contacts provided on the substrate  620  may be formed, e.g., using ENIG plating techniques, as described above. In the embodiment shown in  FIG. 9B , six components  135  are shown. In other embodiments, greater or fewer components  135  may be used. 
     In step  804 , the image sensor die  645  is attached to the substrate  620 , using, for example, conventional flip-chip mounting techniques.  FIG. 5C  is a perspective view of the bottom side  621   b  of the substrate  620  with the image sensor die  645  flip-chip mounted thereto. 
     In step  805 , shown in  FIGS. 9D-9E , the lens module  650  is coupled to the substrate  620 . The lens housing  652  of the lens module  650  may be attached to the substrate  620  by depositing an adhesive, such as an epoxy adhesive, onto a portion of the substrate  620  not otherwise used for electrical connections. A thermal curing step may then be used to cure the adhesive. The lens module connections (not shown) on the substrate  620  may then be coupled to the corresponding contacts (not shown) in the lens housing  652  using, for example, conventional soldering methods. Any known technique may be used for positioning the lens module  650  onto the substrate  620 , as described above. 
       FIG. 9D  is a perspective view of the bottom side  621   b  of the substrate  620  coupled with the lens module  650 , and  FIG. 9E  is a perspective view of the top side  621   a  of the substrate  620  coupled with the lens module  650 . 
     In step  806 , each of the camera modules  610  are then coupled to the chassis  602 . The chassis  602  may be formed using any of a variety of materials and methods to achieve the desired structure. In one embodiment, the chassis  602  comprises an aluminum chassis body  605  which is machined to form the camera support structures  603  and the mounting posts  640 . In other embodiments, the support structures  603  and the posts  640  may be formed separately and attached to the chassis body  605 . 
     In this embodiment, the camera modules  610  are not adhered directly to the chassis body  605 , as with the system  100  in  FIG. 1 . Instead, the flanges  654  of the lens modules  650  are positioned onto the platforms  604  such that the mounting posts  640  are received in the guiding holes  630 . An adhesive may be applied between the flanges  654  and the platforms  604  to provide a more secure coupling between the camera modules  610  and the chassis  602 . With this configuration, an air gap  680  may be provided between the chassis body  605  and both the lower side  621   b  of the substrate  620  and the image sensor die  645 . This air gap  680  can facilitate the cooling of the image sensor die  645  when the camera system  600  is in use. 
     A flex circuit or other connector can be used to connect the main board contact region  644  of the substrate  620  to the main board of the camera system  600 . The connector may be attached to the main board contact region  644  before or after the camera modules  610  are attached to the chassis  602 . 
     In the completed assembly shown in  FIG. 6 , four camera modules  610   a - 610   d  are used to provide a 360° field-of-view on a single plane. In other embodiments, greater or fewer camera modules may be provided in the camera system  600 , and the optical axes of the camera modules need not be co-planar. 
     In addition, in the illustrated embodiment, each of the flanges  654  of each camera module  610  includes two guiding holes  630 . In other embodiments, greater or fewer guiding holes  630 , e.g., one, two, three, or four holes, may be used. In addition, greater or fewer mounting features (e.g., flanges  654 ) and different configurations of mounting features may be used. 
       FIG. 10  is a perspective view of a camera system  1000  in accordance with embodiments of the present invention. This system  1000  includes a rectangular chassis  1002  having four sides onto which four digital camera modules  1010   a - 110   d  are mounted, similar to chassis  102  above. The four digital camera modules  1010   a - 110   d  are positioned on the chassis  1002  such that their respective optical axes are directed in orthogonal directions. 
     In the system  1000  shown in  FIG. 10 , each camera module  1010  includes a flexible tape substrate  1020  coupled to a stiffener member  1090 , with a pair of guiding holes  1030  etched through the stiffener member  1090 . When the camera modules  1010   a - 1010   d  are attached to the chassis  1002 , precisely positioned mounting posts  1040  on the chassis  1002  are received in the guiding holes  1030  to ensure that each camera module  1010  is positioned precisely in the desired location. 
       FIG. 11  is an exploded perspective view of the camera module  1010  comprising a substrate coupled to a stiffener member, with a pair of guiding holes etched in the stiffener member, in accordance with embodiments of the present invention. 
     The camera module  1010  comprises a silicon substrate  1020 , an image sensor die  1045 , a lens module  1050 , and electronic components  135 . The lens module  1050  comprises an autofocus lens housing  1052  forming a cavity containing one or more lenses which are supported by a lens barrel  1056 . The lens barrel  1056  is driven by motors or actuators in the lens housing  1052  to rotate, thereby translating the lens barrel  1056  up and down along optical axis  1048 . 
     The substrate  1020  may comprise, for example, a flexible substrate, such as a flexible high density interconnect (HDI) tape substrate, which is available in very thin configurations. The HDI tape substrate may comprise a multilayer interconnect structure using polyimide as a dielectric and electroplated copper conductor lines, The flexible substrate  1020  may comprise a flexible base material comprising, e.g., polyester, polyimide, polyethylene napthalate, or polyetherimide, and conductive layers comprising, e.g., conductive metal foil, electroplated copper, screen printing metal circuits, or other conductive materials. 
     A stiffener member  1090  is coupled to a lower surface  1021   b  of the flexible substrate  1020  opposite the lens module  1050 . The flexible substrate  1020  includes an image sensor opening  1022 , which exposes a portion of the stiffener member  1090 . The image sensor die  1045  is positioned in the image sensor opening  1022  and coupled to the exposed portion of the stiffener member  1090 . 
     In some embodiments, the upper surface of the image sensor die  1045  is approximately coplanar with an upper surface  1021   a  of the flexible substrate  1020 . The thickness of a flexible tape substrate  1020  having a suitable interconnect structure may be, for example, approximately 0.16 mm, 0.18 mm, or 0.20 mm. The image sensor die  1045  may have a thickness of approximately 0.185 mm, and be attached to the stiffener member  1090  using an epoxy adhesive layer having a thickness of approximately 0.03 mm. Alternatively, substrate  720  may comprise a BT/FR4 laminate substrate, which may have a thickness of approximately 0.3 mm-0.4 mm. 
     The stiffener member  1090  may comprise any material, such as a metallic, composite, polymer, or laminate, that provides sufficient rigidity to the flexible substrate  1020  to provide a stable structure for coupling the camera module  1010  to the chassis  1002 . The stiffener member  1090  may comprise, for example, a sheet of metal having a thickness of approximately 0.15 mm to 0.20 mm. Stainless steel may be desirable as it can be produced with a highly uniform planarity and thickness. In other embodiments, the stiffener member  1090  may comprise copper, which provides good thermal conductivity, or nickel plated copper, which provides additional stiffness. Alternatively, the stiffener member  1090  may comprise a laminate, such as a glass-reinforced epoxy laminate sheet, e.g., FR4/FR5. The stiffener member  1090  may be coupled to the flexible substrate  1020  using, for example, an epoxy, adhesive film, or other adhesive material. Guiding holes  1030   a - 130   b  may be formed in the substrate  1020  using, for example, conventional lithography techniques to mask and etch the guiding holes  1030   a - 130   b  through the substrate  1020 . 
     The upper side  1021   a  of the substrate  1020  includes a plurality of substrate-sensor contacts  1029 . The image sensor die  1045  includes a plurality of output die contacts  1041  formed along one or more edges of the image sensor die  1045 . The output die contacts  1041  are coupled to the substrate-sensor contacts  1029 , as will be described in greater detail below. 
     In the illustrated embodiment, the upper side  1021   a  of the substrate  1020  includes a plurality of component contacts  1034  for coupling with the electronic components  135 . The upper side  1021   a  of the flexible substrate  1020  further includes a main board contact region  1144 . The main board contact region  1144  can include a plurality of contacts  1146 , which can be, for example, ACF contacts or LGA pads which may be coupled to main board contacts on the main board of the camera system. The contacts  1146  receive all of the power and I/O signals required for operation of the camera module  1010 . The contacts  1146  can be coupled to a FPC, bonded (e.g., soldered) directly to corresponding contacts on the main board, coupled to an LGA socket mounted to the main board, or coupled to another intermediate interposer structure, such as a cable or circuit board, which is in turn coupled to the main board. 
     The image sensor die  1045  includes a photosensor portion  1044  comprising any type of image capturing element that converts an optical image into an electronic signal, such as, e.g., a CCD or CMOS active pixel sensor. 
     An optical filter (not shown) may be supported above the image sensor die  1045  by a spacer member (not shown), similar to the optical filter described above. 
       FIG. 12  is a flowchart illustrating a method  1200  of manufacturing a camera system  1000  with a rigid substrate  1020  having guiding holes  1030 , in accordance with embodiments of the present invention.  FIGS. 5A-5D  illustrate various steps in the manufacturing method  500 . 
     In step  1201 , the image sensor die  1045  is formed, similar to the image sensor die  145  described above. The die contacts  1041  on the image sensor die  1045  may be used for wire bonding with the substrate  1020 . The die contacts  1041  may be formed using any of a variety of well-known techniques, such as, for example, using ball bonds. 
     In step  1202 , a stiffener member  1090  is provided, as shown in  FIG. 13A . The stiffener member  1090  comprises one or more guiding holes  1030   a - 1030   b  and one or more fiducial marks  1024 . Fiducial marks  1024  may be formed on the upper surface  1091   a  of the stiffener member  1090  to facilitate machine vision alignment of the stiffener member  1090  with the various components of the camera module  1010 . The stiffener member  1090  can be manufactured using any method to produce the desired characteristics. In one embodiment, a plurality of stiffener members  1090  are formed from a single 2′×2′ stainless steel sheet. The guiding holes  1030   a - 1030   b  may be formed in the sheet using, e.g., mechanical punching or chemical etching processes. The guiding holes  1030   a - 1030   b  may be formed in a batch process before the sheet is divided into individual stiffener members  1090 , or in individual stiffener members  1090  after the stiffener members  1090  are singulated from the sheet. The stiffener members  1090  may be singulated from the sheet suing, e.g., mechanical stamping or chemical etching processes. 
       FIG. 13B  is a perspective view of an alternative embodiment of a stiffener member  1090 ′ in which a die attach cavity  1046  is formed on the upper surface  1091   a ′ of the substrate  1090 ′. The die attach cavity  1046  is sized so as to permit the image sensor die  1044  to be received in the cavity  1046 . This can reduce the height of the combined stiffener member  1090 ′ and die  1044 , which can enable a reduction in the overall height of the camera module  1010 . The die attached cavity  1046  can be formed by etching or any other desired process. 
     In step  1203 , the flexible tape substrate  1020  is coupled to the stiffener member  1090 , as shown in  FIG. 13C . The flexible tape substrate  1020  may be adhered to the stiffener member  1090  using, e.g., a pressure sensitive adhesive (PSA) film. In some embodiments, a plurality of flexible tape substrates  1020  are initially provided on a single continuous tape. The PSA film may be adhered to the lower surface  1021   b  of the flexible substrate  1020  before the substrate  1020  has been separated from the other substrates  1020  in the continuous tape. The PSA film for a plurality of substrates  1020  may also be provided a part of a single continuous film which is adhered to the entire length of the continuous tape of substrates  1020 . After the PSA film is applied to the lower surface  1021   b , the image sensor openings  1022  may be cut out of each substrate  1020 , the individual substrates  1020  separated from the continuous tape, and then the PSA film layer of each substrate  1020  can be pressed against a stiffener member  1090  to adhere the substrate  1020  to the stiffener member  1090 . 
     The upper side  1021   a  of the substrate  1020  further includes a plurality of component contacts  1034  around the periphery of the image sensor opening  1022 . In step  1204 , the electronic components  135  may be coupled to each of these contacts  1034  using, e.g., SMT processes. A plurality of lens module connections (not shown) may be provided along the outer edges of the substrate  1020  for coupling with corresponding contacts (not shown) in the lens housing  1052 . These lens module connections may be used to provide power, ground, and control signals to the lens module  1050 . The various contacts provided on the substrate  1020  may be formed, e.g., using ENIG plating techniques. In the embodiment shown in  FIG. 13D , six components  135  are shown. In other embodiments, greater or fewer components  135  may be used. 
     In step  1205 , shown in  FIG. 13D , the image sensor die  1045  is positioned inside the image sensor opening  1022  and attached to the upper side  1091   a  of the stiffener member  1090 , using, for example, an epoxy adhesive. 
     In step  1206 , the die contacts  1041  on the upper surface of each image sensor die  1045  are wire bonded to substrate-sensor contacts  1029  on the upper surface of the flexible substrate  1020 . Each of the die contacts  1041  is coupled to a respective one of the substrate-sensor contacts  1029  using a bond wire  1042 , e.g., a gold bond wire. 
     In step  1207 , shown in  FIG. 13E , the lens module  1050  is coupled to the substrate  1020 . The lens housing  1052  of the lens module  1050  may be attached to the substrate  1020  by depositing an adhesive, such as an epoxy adhesive, onto a portion of the substrate  1020  not otherwise used for electrical connections. A thermal curing step may then be used to cure the adhesive. The lens module connections (not shown) on the substrate  1020  may then be coupled to the corresponding contacts (not shown) in the lens housing  1052  using, for example, conventional soldering methods. In some embodiments, the lens module  1050  is adhered entirely to the upper side  1021   a  of the flexible substrate  1020 . In other embodiments, the lens module  1050  is adhered partially to the upper side  1021   a  of the flexible substrate  1020  and partially to the upper side  1091   a  of the stiffener member  1090  below. The lens module  1050  may be positioned onto the substrate  1020  using any of the methods described above with respect to the positioning of lens module  150  onto the substrate  120 . 
     In step  1208 , each of the camera modules  1010  are then coupled to the chassis  1002 . The chassis  1002  and mounting posts  1040  may be formed using any of a variety of materials and methods to achieve the desired structure, similar to the chassis  102  and mounting posts  140  described above. A flex circuit or other connector can be used to connect the main board contact region  1144  of the substrate  1020  to the main board of the camera system  1000 . The connector may be attached to the main board contact region  1144  before or after the camera modules  1010  are attached to the chassis  1002 . 
     In the completed assembly shown in  FIG. 10 , four camera modules  1010   a - 110   d  are used to provide a 360° field-of-view on a single plane. In other embodiments, greater or fewer camera modules may be provided in the camera system  1000 , and the optical axes of the camera modules need not be co-planar. In some embodiments, an upward-facing camera module and a downward-facing camera module may be added to provide a complete panoramic image in all directions. 
     In addition, in the illustrated embodiment, the substrate  1020  of each camera module  1010  includes two guiding holes  1030  positioned along opposing edges of the substrate  1020 . In other embodiments, greater or fewer guiding holes  1030 , e.g., one, two, three, or four holes, may be used. 
       FIG. 14  is a perspective view of a camera system  1400  in accordance with other embodiments of the present invention. This system  1400  includes a rectangular chassis  1402  having four sides onto which four digital camera modules  1410   a - 1410   d  are mounted. As with camera system  1000  in  FIG. 10 , the four digital camera modules  1410   a - 1410   d  are positioned on the chassis  1402  such that their respective optical axes are directed in orthogonal directions. 
       FIG. 15  is an exploded perspective view of a camera module  1410  with a lens housing  1452  having mounting features with guiding holes formed therein, in accordance with embodiments of the present invention. 
     In the system  1400  shown in  FIGS. 14-15 , each camera module  1410  includes a flexible tape substrate  1420  coupled to a stiffener member  1490 . A first sensor opening  1422  is formed in the flexible tape substrate  1420  and a second sensor opening  1492  is formed in the stiffener member  1490 . 
     The substrate  1420  may comprise, for example, a flexible substrate, such as a flexible HDI tape substrate, which is available in very thin configurations. The HDI tape substrate may comprise a multilayer interconnect structure using polyimide as a dielectric and electroplated copper conductor lines, The flexible substrate  1420  may comprise a flexible base material comprising, e.g., polyester, polyimide, polyethylene napthalate, or polyetherimide, and conductive layers comprising, e.g., conductive metal foil, electroplated copper, screen printing metal circuits, or other conductive materials. 
     The stiffener member  1490  may comprise any material, such as a metallic, composite, polymer, or laminate, that provides sufficient rigidity to the flexible substrate  1420  to provide a stable structure for coupling the camera module  1410  to the chassis  1402 . The stiffener member  1490  may comprise, for example, a sheet of metal having a thickness of approximately 0.15 mm to 0.20 mm. Stainless steel may be desirable as it can be produced with a highly uniform planarity and thickness. In other embodiments, the stiffener member  1490  may comprise copper, which provides good thermal conductivity, or nickel plated copper, which provides additional stiffness. Alternatively, the stiffener member  1490  may comprise a laminate, such as a glass-reinforced epoxy laminate sheet, e.g., FR4/FR5. The stiffener member  1490  may be coupled to the flexible substrate  1420  using, for example, an epoxy, adhesive film, or other adhesive material. In some embodiments, a desired characteristic of the stiffener member  1490  is a coefficient of thermal expansion that is similar to the coefficient of thermal expansion of the flexible tape substrate  1420 . As a result, as the temperature of the camera system  1400  rises during operation (e.g., due to the heating caused by the image sensor die  1445 ), the stiffener member  1490  and flexible tape substrate  1420  will expand at close to the same rate, thereby avoiding warpage, separation, or other damage that might result if the stiffener member  1490  and flexible tape substrate  1420  expanded at different rates. 
     The image sensor die  1445  includes a photosensor portion  1444  comprising any type of image capturing element that converts an optical image into an electronic signal, such as, e.g., a CCD or CMOS active pixel sensor. An optical filter (not shown) may be supported above the image sensor die  1445  by a spacer member (not shown), similar to the optical filter described above. 
     The lens module  1450  is coupled to an upper side  1491   a  of the stiffener member  1490 . The lower side  1491   b  of the stiffener member  1490  is coupled to an upper side  1421   a  of the flexible tape substrate  1420 . The lower side  1421   b  of the flexible tape substrate  1420  is coupled to the image sensor die  1445  and electronic components  135 . The lower side  1421   b  of the flexible tape substrate  1420  also includes a main board contact region  1444  with a plurality of contacts  1446 . The contacts  1446  receive all of the power and I/O signals required for operation of the camera module  1410 . The contacts  1446  can be coupled to an FPC, bonded (e.g., soldered) directly to corresponding contacts on the main board, coupled to an LGA socket mounted to the main board, or coupled to another intermediate interposer structure, such as a cable or circuit board, which is, in turn, coupled to the main board. 
     The lens module  1450  comprises a lens housing  1452 , which includes a pair of mounting features for aligning the camera modules  1410  with the chassis  1402 . In the embodiment illustrated in  FIGS. 14-15 , the mounting features comprise a pair of flanges  1454  extending from opposite sides of the lens housing  1452  and guiding holes  1430 - 1430   b  formed in the flanges  1454 . Like the lens module  1050 , the lens module  1450  comprises an autofocus lens housing  1452  forming a cavity containing one or more lenses which are supported by a lens barrel  1456 . 
     The chassis  1402  comprises four camera support structures  1403 , each structure  1403  including platforms  1404  onto which the flanges  1454  are positioned. The platforms  1404  include mounting posts  1440 . When the camera modules  1410   a - 1410   d  are attached to the chassis  1402 , precisely positioned mounting posts  1440  on the chassis  1402  are received in the guiding holes  1430  to ensure that each camera module  1410  is positioned precisely in the desired location. The guiding holes  1430  and mounting posts  1440  also serve to maintain the camera modules  1410   a - 1410   d  in their respective positions during handling and use after the manufacturing process is completed. In some embodiments, fasteners  1442  may be used as described above with respect to the embodiment illustrated in  FIG. 6 . 
       FIG. 16  is a flowchart illustrating a method  1600  of manufacturing a camera system  1400  with a lens module  1450  having guiding holes  1430 , in accordance with embodiments of the present invention.  FIGS. 9A-9E  illustrate various steps in the manufacturing method  1600 . 
     In step  1601 , the image sensor die  1445  is formed with a plurality of die contacts. The die contacts can be formed in a variety of ways, depending on the desired method of coupling the image sensor die  1445  to the substrate  1420 . In the embodiment illustrated in  FIGS. 14-15 , the image sensor die  1445  is configured for flip-chip mounting to the substrate  1420 , as will be described in more detail below. 
     In step  1602 , a substrate  1420  is provided.  FIG. 17A  is a perspective view of the bottom side  1421   b  of the substrate  1420 . Fiducial marks  1424  may be formed on the lower surface  1421   b  of the substrate  1420  to facilitate machine vision alignment of the substrate  1420  with the various components to be mounted to the substrate  1420 . 
     In step  1603 , the stiffener member  1490  is attached to the substrate  1420 . 
     The lower side  1421   b  of the substrate  1420  further includes a plurality of component contacts  1434  around the periphery of the image sensor opening  1422 . In step  1604 , the electronic components  135  may be coupled to each of these contacts  1434  using, e.g., SMT processes. The various contacts provided on the substrate  1420  may be formed, e.g., using ENIG plating techniques, as described above. In the embodiment shown in  FIG. 17B , six components  135  are shown. In other embodiments, greater or fewer components  135  may be used. 
     In step  1605 , the image sensor die  1445  is attached to the substrate  1420 , using, for example, conventional flip-chip mounting techniques.  FIG. 17B  is a perspective view of the bottom side  1421   b  of the substrate  1420  with the image sensor die  1445  flip-chip mounted thereto. 
     In step  1606 , shown in  FIGS. 17C-17D , the lens module  1450  is coupled to the stiffener member  1490 . The lens housing  1452  of the lens module  1450  may be attached to the stiffener member  1490  by depositing an adhesive, such as an epoxy adhesive, onto the stiffener member  1490  prior to coupling the lens housing  1452  to the stiffener member  1490 . A thermal curing step may then be used to cure the adhesive. In the illustrated embodiment, the lens module  1450  includes a fixed focus lens and does not incorporate a VCM or other actuator for adjusting the focus of the lens. As a result, the lens module  1450  does not need to be provided with power or other electrical connections with the substrate  1420 . Any known technique may be used for positioning the lens module  1450  onto the stiffener member  1490 , as described above. 
       FIG. 17C  is a perspective view of the lens module  1450  coupled to the top side  1491   a  of the stiffener member  1490 .  FIG. 17D  is a perspective view of the bottom side  1421   b  of the substrate  1420  coupled with the stiffener member  1490  and the lens module  1450 . 
     In step  1607 , each of the camera modules  1410  are then coupled to the chassis  1402 . The chassis  1402  may be formed using any of a variety of materials and methods to achieve the desired structure. In one embodiment, the chassis  1402  comprises an aluminum chassis body  1405  that is machined to form the camera support structures  1403  and the mounting posts  1440 . In other embodiments, the support structures  1403  and the posts  1440  may be formed separately and attached to the chassis body  1405 . 
     In this embodiment, the camera modules  1410  are not adhered directly to the chassis body  1405 , as with the system  100  in  FIG. 1 . Instead, the flanges  1454  of the lens modules  1450  are positioned onto the platforms  1404  such that the mounting posts  1440  are received in the guiding holes  1430 . An adhesive may be applied between the flanges  1454  and the platforms  1404  to provide a more secure coupling between the camera modules  1410  and the chassis  1402 . With this configuration, an air gap  1480  may be provided between the chassis body  1405  and both the lower side  1421   b  of the substrate  1420  and the image sensor die  1445 . This air gap  1480  can facilitate the cooling of the image sensor die  1445  when the camera system  1400  is in use. 
     A flex circuit or other connector can be used to connect the main board contact region  1444  of the substrate  1420  to the main board of the camera system  1400 . The connector may be attached to the main board contact region  1444  before or after the camera modules  1410  are attached to the chassis  1402 . 
     In the completed assembly shown in  FIG. 14 , four camera modules  1410   a - 1410   d  are used to provide a 360° field-of-view on a single plane. In other embodiments, greater or fewer camera modules may be provided in the camera system  1400 , and the optical axes of the camera modules need not be co-planar. 
     In addition, in the illustrated embodiment, each of the flanges  1454  of each camera module  1410  includes two guiding holes  1430 . In other embodiments, greater or fewer guiding holes  1430 , e.g., one, two, three, or four holes, may be used. In addition, greater or fewer mounting features (e.g., flanges  1454 ) and different configurations of mounting features may be used. 
     The above-described embodiments may achieve a number of advantages over conventional camera module designs. The overall size of the camera module may be reduced and the multiple camera modules can be precisely positioned relative to each other and to the chassis. 
     While the invention has been described in terms of particular embodiments and illustrative figures, those of ordinary skill in the art will recognize that the invention is not limited to the embodiments or figures described. Many of the embodiments described above are directed to a 360° panoramic camera system. However, other embodiments may be implemented with greater or fewer cameras configured in any desired arrangement. 
     Although the processes, flowcharts, and methods described herein may describe a specific order of execution, it is understood that the order of execution may differ from that which is described. For example, the order of execution of two or more blocks or steps may be scrambled relative to the order described. Also, two or more blocks or steps may be executed concurrently or with partial concurrence. Further, in some embodiments, one or more of the blocks or steps may be skipped or omitted. It is understood that all such variations are within the scope of the present disclosure. 
     It should be emphasized that the above-described embodiments of the present disclosure are merely possible examples of implementations set forth for a clear understanding of the principles of the disclosure. Many variations and modifications may be made to the above-described embodiment(s) without departing substantially from the spirit and principles of the disclosure. All such modifications and variations are intended to be included herein within the scope of this disclosure and protected by the following claims.