PATENT DOCUMENT

Publication Number: US-9019710-B2
Application Number: US-201213649324-A
Country: US
Kind Code: B2

Title: Devices having flexible printed circuits with bent stiffeners

Abstract:
A flexible printed circuit may be laminated to a metal stiffener. The stiffener may be bent to hold the flexible printed circuit in a desired position. Openings may be formed in the stiffener. Metal traces on the flexible printed circuit may be accessed through the openings. Test points in the metal traces may be accessed through the openings or components may be mounted to the metal traces on the flexible printed circuit through the openings. The stiffener may have bends. The bends may be used to shape the stiffener and flexible printed circuit to form an enclosure. The openings in the stiffener may overlap the bends or may be located away from the bends. Flexible printed circuits mounted on bent stiffeners may be used to form elongated tubes with planar sides.

Claims:
What is claimed is: 
     
       1. An apparatus, comprising:
 a flexible printed circuit; and 
 a bent sheet metal stiffener laminated to the flexible printed circuit, wherein the bent sheet metal stiffener has an opening that overlaps at least a portion of the flexible printed circuit such that the portion of flexible printed circuit is exposed through and completely covers the opening in the bent sheet metal stiffener. 
 
     
     
       2. The apparatus defined in  claim 1  wherein the bent sheet metal stiffener is bent along a bend axis and wherein the opening in the bent sheet metal stiffener overlaps the bend axis. 
     
     
       3. The apparatus defined in  claim 1  wherein the bent sheet metal stiffener is bent along a bend axis and wherein the opening in the bent sheet metal stiffener does not overlap the bend axis. 
     
     
       4. The apparatus defined in  claim 1  further comprising test points on the flexible printed circuit that are accessible through the opening. 
     
     
       5. The apparatus defined in  claim 1  wherein the sheet metal stiffener comprises stainless steel with a thickness of 0.05 to 0.2 mm. 
     
     
       6. The apparatus defined in  claim 1  wherein the bent sheet metal stiffener is configured to form a mounting bracket. 
     
     
       7. The apparatus defined in  claim 6  wherein the mounting bracket has screw holes. 
     
     
       8. The apparatus defined in  claim 1  wherein the bent sheet metal stiffener has at least three bends. 
     
     
       9. The apparatus defined in  claim 1  wherein the bent sheet metal stiffener is configured to form a tube with multiple flat sides. 
     
     
       10. The apparatus defined in  claim 1  wherein the flexible printed circuit has a flexible tail that extends from the bent sheet metal stiffener. 
     
     
       11. The apparatus defined in  claim 10  further comprising at least one component mounted to the flexible tail. 
     
     
       12. The apparatus defined in  claim 1  further comprising an electrical component mounted to the flexible printed circuit through the opening. 
     
     
       13. The apparatus defined in  claim 1  wherein the bent sheet metal stiffener has a notch and wherein the flexible printed circuit has a flexible tail that extends from the bent sheet metal stiffener at the notch. 
     
     
       14. An apparatus, comprising:
 a flexible printed circuit; 
 a bent sheet metal stiffener laminated to the flexible printed circuit, wherein the bent sheet metal stiffener has an opening, and wherein a portion of flexible printed circuit is directly adjacent to and exposed through the opening; and 
 at least one electrical component mounted to the flexible printed circuit, wherein the flexible printed circuit has a plurality of flat regions and a plurality of bent regions and wherein each bent region is interposed between two of the flat regions. 
 
     
     
       15. The apparatus defined in  claim 14 , wherein the flexible printed circuit has a cross-sectional shape selected from the group consisting of: a triangular cross-sectional shape and a rectangular cross-sectional shape. 
     
     
       16. The apparatus defined in  claim 14 , wherein the flexible printed circuit has opposing interior and exterior surfaces, wherein the interior surface is surrounded by the exterior surface, and wherein the bent sheet metal stiffener is laminated to the exterior surface of the flexible printed circuit. 
     
     
       17. The apparatus defined in  claim 14 , wherein the flexible printed circuit has opposing interior and exterior surfaces, wherein the interior surface is surrounded by the exterior surface, and wherein the bent sheet metal stiffener is laminated to the interior surface of the flexible printed circuit. 
     
     
       18. The apparatus defined in  claim 14  further comprising a tube-shaped housing structure, wherein the flexible printed circuit is surrounded by the tube-shaped housing structure. 
     
     
       19. The apparatus defined in  claim 18 , wherein the tube-shaped housing structure comprises a clutch barrel. 
     
     
       20. The apparatus defined in  claim 1 , wherein the opening and the bent sheet metal stiffener are coplanar. 
     
     
       21. The apparatus defined in  claim 2 , wherein the opening is completely surrounded by the bent sheet metal stiffener. 
     
     
       22. The apparatus defined in  claim 13 , wherein the notch comprises an opening that is only partially surrounded by the bent sheet metal stiffener. 
     
     
       23. The apparatus defined in  claim 14 , wherein the at least one electrical component is mounted to the flexible printed circuit through the opening. 
     
     
       24. The apparatus defined in  claim 14 , wherein the opening and the bent sheet metal stiffener are coplanar.

Description:
BACKGROUND 
     This relates generally to electronic devices and, more particularly, to electronic devices with flexible printed circuit structures. 
     Electronic devices often include printed circuits. Rigid printed circuits are formed from materials such as fiberglass-filled epoxy that are inflexible. Flexible printed circuits are formed from layers of polyimide or other sheets of flexible polymer. Integrated circuits, sensors, cameras, and other components may be mounted to pattered metal traces on rigid and flexible printed circuits. 
     In some device configurations, it can be difficult or impossible to mount components within a device housing rigid printed circuits. Flexible printed circuits can be used to address these challenging mounting conditions. Flexible printed circuits may, however, offer insufficient mounting stability. If care is not taken, a component that is mounted to a flexible printed circuit in an electronic device may move during use of the device by a user. This may cause damage to the component and may give rise to reliability issues. 
     It would therefore be desirable to be able to provide improved arrangements for mounting components in electronic devices using flexible printed circuits. 
     SUMMARY 
     A flexible printed circuit may be formed from a flexible sheet of polymer such as a layer of polyimide. Metal traces may be formed in the flexible printed circuit. The flexible printed circuit may be laminated to a metal stiffener such as a sheet of stainless steel or other metal. 
     The stiffener may be bent to hold the flexible printed circuit in a desired position. Openings may be formed in the stiffener. Metal traces on the flexible printed circuit may be accessed through the openings. For example, test points may be accessed through the openings and components may be mounted to the flexible printed circuit through the openings. 
     The stiffener may be used to form a mounting bracket for a component in an electronic device. Screws or other fasteners may be used to mount the stiffener within a device housing and may be used to mount components to the stiffener. 
     The stiffener may have bends. The bends may be used to shape the stiffener and flexible printed circuit to form an enclosure. Integrated circuits or other components may be mounted in the enclosure. Components may also be mounted to exterior portions of the enclosure. The openings in the stiffener may overlap the bends or may be located so as to be formed on a planar portion of the flexible printed circuit. 
     Flexible printed circuits mounted on bent stiffeners may be used to form elongated tubes with planar sides. Flexible printed circuits may be mounted on one or both sides of a sheet metal stiffener. Elongated tube-shaped flexible printed circuits with stiffeners may be mounted within housing enclosures such as clutch barrel enclosures in a laptop computer. 
     Further features, their nature and various advantages will be more apparent from the accompanying drawings and the following detailed description of the preferred embodiments. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an illustrative electronic device such as a laptop computer with flexible printed circuit component mounting structures in accordance with an embodiment. 
         FIG. 2  is a perspective view of an illustrative electronic device such as a handheld electronic device with flexible printed circuit component mounting structures in accordance with an embodiment. 
         FIG. 3  is a perspective view of an illustrative electronic device such as a tablet computer with flexible printed circuit component mounting structures in accordance with an embodiment. 
         FIG. 4  is a perspective view of an illustrative electronic device such as a computer display with flexible printed circuit component mounting structures in accordance with an embodiment. 
         FIG. 5  a schematic diagram of an illustrative electronic device of the type that may be provided with flexible printed circuit component mounting structures in accordance with an embodiment. 
         FIG. 6  is a cross-sectional side view of an illustrative electronic device having flexible printed circuit component mounting structures in accordance with an embodiment. 
         FIG. 7  is a diagram of an illustrative system being used to form an electronic device having components mounted using a flexible printed circuit with a stiffener in accordance with an embodiment. 
         FIG. 8A  is a front perspective view of an illustrative flexible printed circuit with a bent stiffener in accordance with an embodiment. 
         FIG. 8B  is a rear perspective view of the illustrative flexible printed circuit with the bent stiffener of  FIG. 8A  in accordance with an embodiment. 
         FIG. 9  is a perspective view of an illustrative flexible printed circuit having a stiffener that is bent along a bend axis that does not overlap an opening in the stiffener in accordance with an embodiment. 
         FIG. 10  is a cross-sectional side view of a flexible printed circuit with a stiffener that has been coupled to device structures in accordance with an embodiment. 
         FIG. 11  is a cross-sectional side view of a flexible printed circuit with a stiffener that has been coupled to device structures and that has a connector for coupling the flexible printed circuit to other structures in accordance with an embodiment. 
         FIG. 12  is a perspective view of an illustrative flexible printed circuit with a bent stiffener that has been used to form an elongated hollow tube having a triangular cross-sectional shape and having components mounted on an exterior surface in accordance with an embodiment. 
         FIG. 13  is a perspective view of an illustrative flexible printed circuit with a bent stiffener that has been used to form an elongated hollow tube having a triangular cross-sectional shape and having components mounted on an interior surface in accordance with an embodiment. 
         FIG. 14  is a perspective view of an illustrative flexible printed circuit with a bent stiffener that has been used to form a hollow tube having a rectangular cross-sectional shape in accordance with an embodiment. 
         FIG. 15  is a cross-sectional end view of an illustrative flexible printed circuit that has been provided with a bent stiffener to form a tube with a triangular cross-sectional shape and that has been mounted within a cavity in an electronic device structure such as a clutch barrel cover in accordance with an embodiment. 
         FIG. 16  is a perspective view of a flexible printed circuit mounted on an unbent stiffener in accordance with an embodiment. 
         FIG. 17  is a diagram of the flexible printed circuit and stiffener of  FIG. 16  following the formation of a cube from the flexible printed circuit and stiffener by bending the flexible printed circuit and stiffener in accordance with an embodiment. 
         FIG. 18  is a perspective view of a flexible printed circuit mounted on a stiffener in a configuration in which the flexible printed circuit and stiffener have aligned openings to accommodate an electronic device structure such as an electrical component or housing structures in accordance with an embodiment. 
         FIG. 19  is a perspective view of a flexible printed circuit mounted on a stiffener so that a portion of the stiffener that has openings is not covered by the flexible printed circuit in accordance with an embodiment. 
         FIG. 20  is a perspective view of a flexible printed circuit mounted on a stiffener in a spiral configuration in accordance with an embodiment. 
         FIG. 21  is a flow chart of illustrative steps involved in forming an electronic device having one or more flexible printed circuits with bent stiffeners in accordance with an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     Illustrative electronic devices that have flexible printed circuits with stiffeners are shown in  FIGS. 1 ,  2 ,  3 , and  4 . 
     Electronic device  10  of  FIG. 1  has the shape of a laptop computer and has upper housing  12 A and lower housing  12 B with components such as keyboard  16  and touchpad  18 . Device  10  has hinge structures  20  (sometimes referred to as a clutch barrel) to allow upper housing  12 A to rotate in directions  22  about rotational axis  24  relative to lower housing  12 B. Display  14  is mounted in upper housing  12 A. 
     Upper housing  12 A, which may sometimes referred to as a display housing or lid, is placed in a closed position by rotating upper housing  12 A towards lower housing  12 B about rotational axis  24 . 
       FIG. 2  shows an illustrative configuration for electronic device  10  based on a handheld device such as a cellular telephone, music player, gaming device, navigation unit, or other compact device. In this type of configuration for device  10 , housing  12  has opposing front and rear surfaces. Display  14  is mounted on a front face of housing  12 . Display  14  may have an exterior layer that includes openings for components such as button  26  and speaker port  28 . 
     In the example of  FIG. 3 , electronic device  10  is a tablet computer. In electronic device  10  of  FIG. 3 , housing  12  has opposing planar front and rear surfaces. Display  14  is mounted on the front surface of housing  12 . As shown in  FIG. 3 , display  14  has an external layer with an opening to accommodate button  26 . 
       FIG. 4  shows an illustrative configuration for electronic device  10  in which device  10  is a computer display or a computer that has been integrated into a computer display. With this type of arrangement, housing  12  for device  10  is mounted on a support structure such as stand  27 . Display  14  is mounted on a front face of housing  12 . 
     The electrical devices of  FIGS. 1 ,  2 ,  3 , and  4  have electrical components mounted on flexible printed circuits with stiffeners. The illustrative configurations for device  10  that are shown in  FIGS. 1 ,  2 ,  3 , and  4  are merely illustrative. In general, electronic device  10  may be 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, 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. 
     Housing  12  of device  10 , which is sometimes referred to as a case, is formed of materials such as plastic, glass, ceramics, carbon-fiber composites and other fiber-based composites, metal (e.g., machined aluminum, stainless steel, or other metals), other materials, or a combination of these materials. Device  10  may be formed using a unibody construction in which most or all of housing  12  is formed from a single structural element (e.g., a piece of machined metal or a piece of molded plastic) or may be formed from multiple housing structures (e.g., outer housing structures that have been mounted to internal frame elements or other internal housing structures). 
     Display  14  may be a touch sensitive display that includes a touch sensor or may be insensitive to touch. Touch sensors for display  14  may be formed from an array of capacitive touch sensor electrodes, a resistive touch array, touch sensor structures based on acoustic touch, optical touch, or force-based touch technologies, or other suitable touch sensor components. 
     Display  14  for device  10  includes display pixels formed from liquid crystal display (LCD) components or other suitable image pixel structures. 
     A display cover layer may cover the surface of display  14  or a display layer such as a color filter layer or other portion of a display may be used as the outermost (or nearly outermost) layer in display  14 . The outermost display layer may be formed from a transparent glass sheet, a clear plastic layer, or other transparent member. 
     A schematic diagram of device  10  is shown in  FIG. 5 . As shown in  FIG. 5 , electronic device  10  includes control circuitry such as storage and processing circuitry  40 . Storage and processing circuitry  40  includes one or more different types of storage such as hard disk drive storage, nonvolatile memory (e.g., flash memory or other electrically-programmable-read-only memory), volatile memory (e.g., static or dynamic random-access-memory), etc. Processing circuitry in storage and processing circuitry  40  is used in controlling the operation of device  10 . The processing circuitry may be based on a processor such as a microprocessor and other integrated circuits. 
     With one suitable arrangement, storage and processing circuitry  40  is used to run software on device  10  such as internet browsing applications, email applications, media playback applications, operating system functions, software for capturing and processing images, software for implementing functions associated with gathering and processing sensor data, etc. 
     Input-output circuitry  32  is 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 circuitry  32  can include wired and wireless communications circuitry  34 . 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, and other circuitry for handling RF wireless signals. Wireless signals can also be sent using light (e.g., using infrared communications). 
     Input-output circuitry  32  of  FIG. 5  includes input-output devices  36  such as buttons, joysticks, click wheels, scrolling wheels, a touch screen such as display  14 , other touch sensors such as track pads or touch-sensor-based buttons, vibrators, audio components such as microphones and speakers, image capture devices such as a camera module having an image sensor and a corresponding lens system, keyboards, status-indicator lights, tone generators, key pads, and other equipment for gathering input from a user or other external source and/or generating output for a user. 
     Sensors  38  of  FIG. 5  include an ambient light sensor for gathering information on ambient light levels. The ambient light sensor includes one or more semiconductor detectors (e.g., silicon-based detectors) or other light detection circuitry. Sensors  38  also include proximity sensor components. The proximity sensor components may include a dedicated proximity sensor and/or a proximity sensor formed from touch sensors (e.g., a portion of the capacitive touch sensor electrodes in a touch sensor array for display  14  that are otherwise used in gathering touch input for device  10 ). Proximity sensor components in device  10  can include capacitive proximity sensor components, infrared-light-based proximity sensor components, proximity sensor components based on acoustic signaling schemes, or other proximity sensor equipment. Sensors  38  may also include a pressure sensor, a temperature sensor, an accelerometer, a gyroscope, and other circuitry for making measurements of the environment surrounding device  10 . 
     It can be challenging to mount electrical components such as the components of  FIG. 5  within an electronic device. To facilitate mounting of components in housing  12  of device  10 , components may be mounted on a flexible printed circuit. 
     A flexible printed circuit has a flexible dielectric substrate formed from a sheet of polyimide or other flexible layer of polymer. A flexible printed circuit also has patterned conductive traces such as one or more layers of patterned metal traces. 
     Stiffening structures formed from metal or other materials are used to stiffen the flexible printed circuit. Stiffening structures are attached to the flexible printed circuit using adhesive. Bent stiffening structures allow the flexible printed circuit to fit within the potentially tight confines of electronic device  10  and other structures. 
     A sheet of metal such as a layer of metal having a thickness of 0.1 mm to 0.3 mm or other suitable thickness may be used to stiffen a flexible printed circuit, so illustrative configurations for stiffeners that are formed from sheet metal are sometimes described herein as an example. This is, however, merely illustrative. Flexible printed circuit stiffeners may, in general, be formed from any suitable material. 
       FIG. 6  is a cross-sectional side view of an illustrative device showing how a flexible printed circuit with a stiffener can be mounted within the device. As shown in  FIG. 6 , electronic device  10  has housing  12 . Display  14  is mounted in housing  12 . Display  14  has a display cover layer such as display cover layer  50  and a display module such as display module  52 . Display cover layer  50  is a clear transparent member such as a layer of clear glass or a layer of transparent plastic. Display module  52  contains liquid crystal display structures, electrowetting display structures, electrophoretic display structures, organic light-emitting diode display structures, or other display structures. 
     Device  10  of  FIG. 6  contains printed circuit board  66  and flexible printed circuit structure  58 . Components  68  are mounted on printed circuit  66 . Components such as component  54  are mounted on flexible printed circuit board  60 . Flexible printed circuit board  60  is stiffened using bent stiffener  62  to form stiffened flexible printed circuit structures  58 . 
     Components  68  and  54  may include integrated circuits, sensors, cameras, buttons, and other components (e.g., circuitry such as storage and processing circuitry  40  and input-output circuitry  32  of  FIG. 5 ). Components such as component  54  are mounted on printed circuits such as flexible printed circuit  60 . With one illustrative example, component  54  is an ambient light sensor, camera module, or other electronic component. Components  68  are integrated circuits, circuitry such as circuitry  40  and  32  of  FIG. 5 , camera module structures, light sensors such as ambient light sensors, proximity sensors, etc. Printed circuit board  66  is preferably a rigid printed circuit board formed from a substrate material such as fiberglass-filled epoxy. Components  68  are soldered or otherwise electrically mounted on printed circuit board  66 . 
     Components such as component  64  are mounted in the interior of device  10 . To avoid interference with internal device structures such as component  64 , printed circuit structures  58  are provided with one or more bends, as shown by the illustrative right-angle bend of  FIG. 6 . As shown in  FIG. 6 , component  54  may be mounted under a portion of display cover layer  50 . As an example, component  54  may be a camera that receives light  56  that is associated with an image through display cover layer  50 . Components such as component  54  may, in general, be any suitable type of component (e.g., a sensor, integrated circuit, connector, discrete component, light-emitting component, audio device, etc.). The use of a camera in the configuration of  FIG. 6  is merely illustrative. 
     Flexible printed circuit material  60  is generally too flexible to independently retain a desired bent shape. However, stiffener  62  is formed from a material that is sufficiently stiff to resist unbending forces. For example, stiffener  62  can be formed from a sheet of stainless steel or other metal that retains its shape following bending (e.g., a sheet of metal having a thickness of less than 0.4 mm, of 0.05 to 0.35 mm, of 0.15 to 0.25 mm, etc.). 
     To retain the shape of bent printed circuit structures  58  of  FIG. 6 , stiffener  62  is bent at a 90° angle, thereby holding flexible printed circuit  60  in a configuration with a 90° bend. Bent flexible printed circuit structures  58  with bends of other angles may also be used in device  10 , if desired. 
     Illustrative equipment for forming bent flexible printed circuit structures  58  and devices  10  incorporating bent flexible printed circuit structures  58  is shown in  FIG. 7 . 
     Patterning equipment  80  is used to form stiffening structures such as stiffener  62 . Equipment  80  may include lasers, milling bits and other machining bits, dies for patterning metal by stamping, and other equipment for patterning metal sheets. As shown in  FIG. 7 , equipment  80  may be used to form stiffeners such as stiffener  62 . Stiffener  62  may be devoid of openings or may have one or more openings such as opening  82 . 
     Component mounting and flexible printed circuit patterning equipment  70  is used to form patterned flexible printed circuits (e.g., by laser trimming, die cutting, or other cutting techniques) and is used to mount components such as component  72 . Component  72  may be an integrated circuit, a camera, an ambient light sensor or other sensor, other components, etc. Solder  74  electrically connects pads in component  72  to pads  76  that are part of metal traces  78  on flexible printed circuit  60 . 
     After forming a patterned flexible printed circuit with optional openings and mounted components such as component  72 , lamination and bending equipment  84  can create bent flexible printed circuit structures  58 . Lamination and bending equipment  84  may, for example, use adhesive to attach flexible printed circuit  60  to metal stiffener  62  and may use a computer-controlled press or other bending tool to bend stiffener  62  and flexible printed circuit  60  into a desired shape. 
     As shown in the illustrative example of  FIG. 7 , bent flexible printed circuit structures  58  can be tested using tester  86 . Tester  86  includes a testing tool such as testing tool  88 . Computer-controlled positioner  96  controls the position of tester  88 . Test head  90  has probe pins  92  that are configured to mate with test pads  78  in the metal traces on flexible printed circuit  60 . Due to the presence of opening  82 , test pins  92  contact test pads  78  on flexible printed circuit  60  when tester  88  and test head  90  are moved in direction  94  during testing. 
     If testing indicates that flexible printed circuit structures  58  include one or more faults, flexible printed circuit structures  58  can be repaired or discarded. If testing with system  86  indicates that flexible printed circuits  58  are operating satisfactorily, flexible printed circuit structures  58  and other structures  100  (e.g., housing structures, additional components, etc.) may be assembled using assembly equipment  98  to produce finished electronic device  10 . 
       FIG. 8A  is a front perspective view of illustrative bent flexible printed circuit structures  58 . As shown in  FIG. 8A , bent flexible printed circuit structures  58  include flexible printed circuit  60  and metal stiffener  62 . Stiffener  62  and flexible printed circuit  60  are bent at an angle A around bend axis  102 . Angle A may have a value of 10-20°, 10-60°, 5-175°, 30-120°, less than 150°, less than 110°, 90°, 45°, less than 60°, 10-50°, more than 15°, or other suitable angle. 
     Opening  82  may overlap bend axis  102 . In configurations in which opening  82  overlaps bend axis  102 , the flexibility of stiffener  62  is enhanced. Any suitable number of openings  82  may overlap bend axis  102  (e.g., one or more, two or more, three or more, etc.). 
     Stiffener  62  of  FIG. 8A  has a notch. Notch  104  allows flexible printed circuit tail  60 B of flexible printed circuit  60  to bend with respect to stiffener  62  (i.e., tail  60 B may bend out of the plane that includes portion  58 B of stiffener  62  and flexible printed circuit  60 . If desired, one or more notches such as notch  104  may be located at the corners of stiffener  62  (e.g., notches may be formed by removing rectangular corner portions of stiffener  62 ). 
     Test pads  78  are accessible through opening  82  by test system  86 . If desired, one or more components such as component  105  may be mounted on flexible printed circuit  60  in opening  104 . Components such as components  106  and  108  of  FIG. 8B  can also be mounted on the rear surface of flexible printed circuit  60 . Component  108  can be a connector such as a board to board connector. Component  106  can be an integrated circuit or other device. 
     Tail portion  60 B of flexible printed circuit  60  has openings  110 . Screws or other fasteners can pass through openings  110  (e.g., to attach tail portion  60 B to a housing structure or other structure). Components such as component  112  may be attached to flexible printed circuit tail  60 B. As an example, component  112  may be an ambient light sensor. 
     In the example of  FIG. 9 , flexible printed circuit structures  58  have been bent to form a right angle in stiffener  62  and flexible printed circuit  60  along bend axis  102 . Opening  116  does not overlap bend axis  102 , thereby increasing the stiffness of stiffener  62  along the bend. Components  114  are formed on flexible printed circuit  60  (e.g., on portions of flexible printed circuit  60  above and below bend axis  102 ). 
     Bent flexible printed circuit structures  58  can be used to form structural elements of device  10  such as mounting brackets or other component support structures. In the illustrative configuration of  FIG. 10 , for example, fasteners such as screws  118  are being used to attach flexible printed circuit structures  58  to device structures  120  (e.g., internal or external housing structures such as portions of housing  12 ). Components such as component  122  (e.g., a connector, camera, etc.) are also attached to flexible printed circuit structures  58  using screws  118 . In this way, structures  58  serve as a mounting bracket or support structure for component  122  to help mount component  122  within device  10 . Components  124  (e.g., integrated circuits, sensors, cameras, etc.) are mounted to flexible printed circuit  60  in flexible printed circuit structures  58  using solder. Circular openings or openings of other shapes are formed in flexible printed circuit  60  and stiffener  62  to accommodate screws  118 . 
     Brackets that are formed from flexible printed circuit structures  58  may have any suitable shape. As an example, brackets may be formed from flexible printed circuit structures  58  that have louvers, press-in inserts, gussets, snaps, springs, or other shapes. Brackets may have multiple openings, engagement features that are configured to engage with other brackets or components, mounting ledges for receiving planar members and other structures, slots for receiving protrusions on components or other structures, etc. The illustrative bracket shape formed by flexible printed circuit structures  58  of  FIG. 10  is merely an example. Flexible printed circuit brackets with bent sheet metal structures may have other shapes, if desired. 
     In the illustrative configuration of  FIG. 11 , printed circuit board  130  has opposing upper and lower surfaces on which components  132  have been mounted. Printed circuit board  130  may be a flexible printed circuit board or a rigid printed circuit board (as examples). Board  130  has board-to-board connector  128 . Board-to-board connector  128  mates with a corresponding board-to-board connector such as connector  126  on flexible printed circuit  60  in bent flexible printed circuit structures  58 . Components such as component  124  (e.g., integrated circuits, cameras, sensors, etc.) are mounted to flexible printed circuit  60 . Metal stiffener  62  holds bent flexible printed circuit structures  58  in the bent configuration of  FIG. 11 . Screws such as screw  118  pass through openings in bent flexible printed circuit structures  58  to attach bent flexible printed circuit structures  58  to housing structures  120 . 
       FIG. 12  shows how bent flexible printed circuit structures  58  may have multiple bends. In the configuration of  FIG. 12 , bent flexible printed circuit structures  58  form an elongated hollow tube. The tubular structures of  FIG. 12  extend along longitudinal axis  134 . There are two bends in bent flexible printed circuit structures  58 , so that bent flexible printed circuit structures  58  have a triangular cross-sectional shape with a triangular interior cavity. Components  136  are mounted to flexible printed circuit  60  on the exterior surfaces of bent flexible printed circuit structures  58 . 
     In the configuration of  FIG. 13 , flexible printed circuit  60  has been formed on the inner surface of the tube formed by structures  58  and components  136  have been mounted on the interior surface of structures  58 . 
       FIG. 14  shows how bent flexible printed circuit structures  58  may have a rectangular cross-sectional shape. In the configuration of  FIG. 14 , bent flexible printed circuit structures  58  have inner layer  138  and outer layer  140 . Layers  138  and  140  are bent to form an elongated hollow tube that extends along longitudinal axis  134 . Layer  138  may be a flexible printed circuit and layer  140  may be a metal stiffening sheet or layer  138  may be a metal stiffening sheet and layer  140  may be a flexible printed circuit. Components  142  may be mounted to the flexible printed circuit on the inside or the outside of the tube. 
       FIG. 15  is a cross-sectional end view of bent flexible printed circuit structures  58  in a configuration in which bent flexible printed circuit structures  58  form an elongated tube (extending into the page in the orientation of  FIG. 15 ). Flexible printed circuit structures  58  of  FIG. 15  are surrounded by housing structures  12 R. Structures  12 R may be part of housing  12  of  FIGS. 1 ,  2 ,  3 , and  4 . For example, housing structures  12 R may form a clutch barrel cover for clutch barrel  20  of  FIG. 1 . 
     As shown in  FIG. 15 , stiffener  62  has been bent to form a tubular shape (extending into the page in the orientation of  FIG. 15 ) having a triangular cross-sectional shape. Flexible printed circuit  60  has two portions. Outer portion  60 - 1  covers the outer surface of stiffener  62 . Inner portion  60 - 2  covers the inner surface of stiffener  62 . This type of two-sided arrangement for flexible printed circuit  60  allows components  142  to be mounted on both the interior and opposing exterior surfaces of the tube-shaped bent flexible printed circuit structures  58  formed using stiffener  62 . 
       FIG. 16  is a perspective view of illustrative flexible printed circuit structures  58  in an unbent configuration. The example of  FIG. 16  shows how flexible printed circuit structures  58  may have an unbent shape that allows flexible printed circuit structures  58  to be bent to form an enclosure such as enclosure  58 E of  FIG. 17 . In the example of  FIGS. 16 and 17 , the unbent structures of  FIG. 16  have a layout that is suitable for forming into the cube-shaped bent structures of  FIG. 17 . Bent flexible printed circuit structures  58 E of other shapes may be formed, if desired. 
     Components  142  may be mounted on the exterior of structures  58 E (when flexible printed circuit  60  has exterior portions), on the interior of structures  58 E (when flexible printed circuit  60  has interior portions), or on both the interior and exterior of structures  58 E (when flexible printed circuit  60  has exterior portions such as portions  60 - 1  of  FIG. 15  and interior portions such as portions  60 - 2  of  FIG. 15 . 
     The interior of structures  58 E is hollow, so additional components can be mounted in the interior of structures  58 E (e.g., batteries, etc.), if desired. 
       FIG. 18  is a perspective view of illustrative bent flexible printed circuit structures  58  with an opening such as opening  150  to accommodate components such as component  152 . Component  152  may be a portion of housing  12 , an electronic component, or other structure in device  10 . Opening  150  may have a notch shape with an open edge or may have a closed shape such as the rectangular shape of  FIG. 18 , a circular shape, a shape with curved edges, a shape with straight edges, or a shape with a combination of straight and curved edges. 
     In the illustrative configuration of  FIG. 19 , portion  156  of stiffener  62  in bent flexible printed circuit structures  58  is uncovered by flexible printed circuit  60 . Leaving portion  156  of stiffener  62  bare of flexible printed circuit materials allows fasteners and other structures to bear directly against stiffener  62  in the vicinity of openings  154 . If desired, flexible printed circuit  60  may have a portion that overhangs the edge of stiffener  62  such as illustrative tail portion  60 B of  FIGS. 8A and 8B . 
       FIG. 20  is a perspective view of bent flexible printed circuit structures  58  in a configuration in which bent flexible printed circuit structures  58  have a spiral shape. Components such as component  142  may be mounted on flexible printed circuit  60 . Spiral-shaped stiffener  62  holds flexible printed circuit  60  in a desired shape such as a shape with a cylindrical shape, as shown in  FIG. 20 . Flexible printed circuit structures  58  of the type shown in  FIG. 20  may have multiple loops (e.g., two or more, five or more, or ten or more) and may be installed within cylindrical portions of housing  12  or other portions of device  10  (as examples). 
     Illustrative steps involved in forming electronic devices having bent flexible printed circuit structures  58  are shown in  FIG. 21 . At step  200 , equipment such as patterning equipment  80  of  FIG. 7  forms stiffener  62 . Openings such as opening  82  can be incorporated into stiffener  62 , if desired. Stiffener  62  may be formed from stainless steel, other metals, or other materials that hold shape when bent. Techniques such as stamping, die cutting, machining using a cutting bit, or other fabrication techniques may be used to form stiffener  62 . 
     At step  202 , flexible printed circuit  60  is patterned and populated with components using equipment  70  ( FIG. 7 ). Techniques such as soldering, die cutting, laser cutting, metal trace patterning, and other techniques may be used in forming flexible printed circuit  60 . 
     At step  204 , flexible printed circuit layer  60  may be laminated to stiffener  62 . Lamination operations may involve the application of a thermally cured adhesive or other adhesive. A heat source such as an oven or heat gun can apply heat to the thermally cured adhesive to facilitate curing. If desired, flexible printed circuit layer  60  may be laminated to stiffener  62  before mounting components on flexible printed circuit layer and/or before patterning flexible printed circuit layer  60 . 
     At step  206 , computer-controlled die presses or other bending equipment may be used to bend stiffener  62  and attached flexible printed circuit  60  into a desired bent shape. 
     At step  208 , after attaching flexible printed circuit  60  to stiffener  62  and bending stiffener  62  and flexible printed circuit  60  into a desired shape to form bent flexible printed circuit structures  58 , circuitry on structures  58  is preferably tested using test system  86  ( FIG. 7 ). If structures  58  fail testing, structures  58  can be reworked or discarded. In response to passing testing, structures  58  and other structures  100  (e.g., device housing structures, additional device components, etc.) can be assembled to form finished electronic device  10  using assembly equipment  98  ( FIG. 7 ). 
     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: 20121011
Publication Date: 20150428
Grant Date: 20150428
Priority Date: 20121011
Inventors: JEZIOREK PETER N.
Assignee: APPLE INC
CPC Classifications: [{"code": "H05K1/189", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K2201/057", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K3/0061", "inventive": true, "first": true, "tree": "[]"}, {"code": "H05K3/0061", "inventive": true, "first": true, "tree": "[]"}, {"code": "H05K1/189", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K2201/057", "inventive": false, "first": false, "tree": "[]"}]
Family ID: 50475132