PATENT DOCUMENT

Publication Number: US-10362670-B2
Application Number: US-201815882836-A
Country: US
Kind Code: B2

Title: Fabric signal path structures for flexible devices

Abstract:
An electronic device such as a cover for a portable device may be provided with a body having hinge portions. The hinge portions may allow the body to bend about one or more bend axes. The cover may have electrical components such as a keyboard. A keyboard may be mounted at one end of the cover and a connector may be mounted at an opposing end of the cover. A flexible fabric signal path structure may be formed from metal traces on a flexible fabric substrate. At one end of the cover, the flexible fabric signal path structure may be coupled to a printed circuit in the keyboard using conductive adhesive. At the opposing end of the cover, the metal traces on the flexible fabric substrate may be coupled to the connector.

Claims:
What is claimed is: 
     
       1. A cover for an electronic device, comprising:
 a body having first and second portions, wherein the body folds along a bend axis between the first and second portions and wherein the body has an exterior surface; 
 a keyboard on the first portion of the body; 
 a connector on the second portion of the body, wherein the connector is located on the exterior surface of the body; and 
 a flexible signal path that crosses the bend axis and that couples the keyboard to the connector, wherein the flexible signal path comprises conductive traces that are perpendicular to the bend axis. 
 
     
     
       2. The cover defined in  claim 1  wherein the body folds along first and second additional bend axes that are parallel to the bend axis, wherein the first additional bend axis is interposed between the bend axis and the second additional bend axis, wherein the cover is configurable in a stand position in which the cover props up and connects to the electronic device, and wherein when the cover is in the stand position, the cover is unfolded at the bend axis and folded at the first and second additional bend axes. 
     
     
       3. The cover defined in  claim 1  wherein the flexible signal path comprises fabric and wherein the flexible signal path comprises a layer of metal on the fabric. 
     
     
       4. The cover defined in  claim 3  wherein the conductive traces comprise metal traces and wherein the layer of metal is patterned to form the metal traces. 
     
     
       5. The cover defined in  claim 4  wherein the connector comprises first, second, and third contacts, and wherein the metal traces include a first metal trace coupled to the first contact, a second metal trace coupled to the second contact, and a third metal trace coupled to the third contact. 
     
     
       6. The cover defined in  claim 1  wherein the keyboard comprises a printed circuit and an array of key switches on the printed circuit. 
     
     
       7. The cover defined in  claim 6  wherein the printed circuit has opposing upper and lower surfaces, wherein the key switches are located on the upper surface, and wherein an electrical contact is located on the lower surface, the cover further comprising:
 conductive adhesive that couples the electrical contact to the flexible signal path. 
 
     
     
       8. The cover defined in  claim 7  further comprising insulating adhesive that at least partially surrounds the conductive adhesive. 
     
     
       9. The cover defined in  claim 7  further comprising a fabric layer that overlaps the array of key switches. 
     
     
       10. The cover defined in  claim 1  wherein the body folds along an additional bend axis and wherein the flexible signal path crosses the additional bend axis. 
     
     
       11. A cover for a tablet computer, comprising:
 a housing having first and second portions separated by a flexible hinge, wherein the second portion folds along at least first and second fold axes; 
 a keyboard in the first portion; 
 a stiffener in the second portion; 
 an electrical contact on an outer surface of the housing; and 
 a conductive signal path that overlaps the flexible hinge and the stiffener, wherein the conductive signal path has a first end coupled to the keyboard and a second end coupled to the electrical contact. 
 
     
     
       12. The cover defined in  claim 11  further comprising:
 first and second additional flexible hinges; and first and second additional stiffeners, wherein the flexible hinge and the first and second additional flexible hinges are interspersed with the stiffener and the first and second additional stiffeners in the second portion. 
 
     
     
       13. The cover defined in  claim 11  wherein the conductive signal path comprises a metal layer on a fabric substrate. 
     
     
       14. The cover defined in  claim 13  wherein the metal layer penetrates through openings in the fabric substrate. 
     
     
       15. The cover defined in  claim 11  wherein the flexible hinge allows the housing to bend about a bend axis and wherein the flexible signal path is perpendicular to the bend axis. 
     
     
       16. A cover for an electronic device, comprising:
 a housing that folds along a bend axis; 
 a plurality of electrical contacts on an outer surface of the housing; 
 a keyboard; 
 a first fabric layer that covers the keyboard; and 
 a second fabric layer that crosses the bend axis and that includes metal traces coupled between the keyboard and the plurality of electrical contacts. 
 
     
     
       17. The cover defined in  claim 16  wherein the housing folds along first and second additional bend axes and wherein the second fabric layer crosses the first and second additional bend axes. 
     
     
       18. The cover defined in  claim 16  wherein the second fabric layer comprises woven fabric and the metal traces are formed from a patterned layer of metal. 
     
     
       19. The cover defined in  claim 16  wherein the keyboard comprises a printed circuit having electrical contacts that are coupled to the metal traces. 
     
     
       20. The cover defined in  claim 19  further comprising a conductive adhesive that couples the electrical contacts to the metal traces.

Description:
This application is a continuation of U.S. patent application Ser. No. 14/843,617, filed Sep. 2, 2015, which is hereby incorporated by reference herein in its entirety. 
    
    
     BACKGROUND 
     This relates generally to electronic devices, and, more particularly, to flexible signal path structures for electronic devices. 
     Electronic devices may include circuitry that is interconnected using signal lines on printed circuits. In some devices, parts of a device may move with respect to each other. For example, the display housing and the base housing of a laptop computer are coupled to each other with a hinge to allow the display housing to move relative to the base housing. Flexible signal cables such as flexible printed circuits with signal busses formed from metal traces can be used to couple circuitry in the base housing of a laptop computer to the display housing of the laptop computer. The signal busses may be used to transfer signals between the base housing and display housing, even as the base housing and display housing are moved with respect to each other about the hinge. 
     Flexible printed circuit cables have flexible polymer substrates such as sheets of polyimide, thin film polyamide (nylon), polyester on which the metal traces for the signal busses are formed. The polymer substrates may not bend as sharply as desired for certain applications and can be difficult to conceal in within some types of devices. 
     It would therefore be desirable to be able to provide improved flexible signal path structures. 
     SUMMARY 
     An electronic device such as a cover for a portable device may be provided with a body having hinge portions or other tight radius flex lines. The hinge portions may allow the body to bend about one or more bend axes. For example, sections of the cover may be folded along the bend axes to create a support for the portable device. The portable device may be a tablet computer or other device without a keyboard. A keyboard for providing input to the portable device may be formed in the cover. 
     The keyboard may be mounted at one end of the cover and a connector that mates with the portable device may be mounted at an opposing end of the cover. A flexible fabric signal path structure may be used to route signals between the keyboard and the connector. The flexible fabric signal path structure may overlap the bend axes of the body and may accommodate bending along the bend axes. 
     The flexible fabric signal path structure may be formed from metal traces on a flexible fabric substrate. At one end of the cover, the flexible fabric signal path structure may be coupled to a printed circuit in the keyboard using conductive adhesive. At the opposing end of the cover, the metal traces on the flexible fabric substrate may be coupled to the connector. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic diagram of illustrative electronic equipment of the type that may include a flexible signal path in accordance with an embodiment. 
         FIG. 2  is a perspective view of an illustrative tablet computer cover with flexible structures that accommodate bending in accordance with an embodiment. 
         FIG. 3  is a cross-sectional side view of an illustrative tablet computer mated with an illustrative tablet computer cover in accordance with an embodiment. 
         FIG. 4  is a cross-sectional side view of a cover of the type shown in  FIG. 3  showing how the cover may be provided with a flexible fabric signal path structure in accordance with an embodiment. 
         FIG. 5  is a perspective view of an illustrative flexible fabric signal path structure in accordance with an embodiment. 
         FIG. 6  is a diagram of an illustrative fabric that may be used in forming the flexible fabric signal path structure of  FIG. 5  in accordance with an embodiment. 
         FIG. 7  is a cross-sectional side view of a portion of a flexible fabric signal path structure in accordance with an embodiment. 
         FIG. 8  is a diagram showing how a flexible fabric substrate may have strands of material that are offset at an acute non-zero angle with respect to a bend axis in accordance with an embodiment. 
         FIG. 9  is a top view of a portion of a flexible fabric signal path structure with a locally enlarged signal path width to enhance reliability when bent in accordance with an embodiment. 
         FIG. 10  is a top view of a portion of a flexible fabric signal path structure with a locally modified portion in which strands of material have a non-zero angular offset relative to a bend axis in accordance with an embodiment. 
         FIG. 11  is a diagram of an illustrative fabric having conductive strands that form a signal path in accordance with an embodiment. 
         FIG. 12  is a cross-sectional side view of circuitry for a case that is being coupled together using a flexible fabric signal path in accordance with an embodiment. 
         FIG. 13  is a top view of an adhesive pattern that may be used in coupling contacts on a flexible fabric signal path structure to another structure such as a printed circuit in accordance with an embodiment. 
         FIG. 14  is a cross-sectional side view of an illustrative flexible fabric signal path structure coupled to a printed circuit in accordance with an embodiment. 
         FIG. 15  is a cross-sectional side view of structures that may be used to help secure a flexible fabric signal path structure to other structures in an electronic device in accordance with an embodiment. 
         FIG. 16  is a cross-sectional side view of a portion of an electronic device having a flexible fabric signal path structure that has been populated with electrical components in accordance with an embodiment. 
         FIGS. 17 and 18  are flow charts of illustrative steps involved in forming flexible fabric signal path structures in accordance with embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     A schematic diagram of illustrative electronic equipment that may be provided with flexible fabric signal path structures is shown in  FIG. 1 . Electronic device  10  and electronic device  10 ′ of  FIG. 1  may be operated independently or may be coupled to each other. A device such as device  10  and/or device  10 ′ may be a computing device such as a laptop computer, a computer monitor containing an embedded computer, a tablet computer, a cellular telephone, a media player, or other handheld or portable electronic device, a smaller device such as a wrist-watch device, a pendant device, a headphone or earpiece device, a device embedded in eyeglasses or other equipment worn on a user&#39;s head, or other wearable or miniature device, a television, a computer display that does not contain an embedded computer, a gaming device, a navigation device, an embedded system such as a system in which electronic equipment with a display is mounted in a kiosk or automobile, a case, bag, watch band, or other accessory that operates in conjunction with one of these devices or other equipment, equipment that implements the functionality of two or more of these devices, or other electronic equipment. As an example, device  10  may be a portable device such as a cellular telephone or media player and device  10 ′ may be an accessory such as a cover (sometimes referred to as a case or enclosure). Other configurations may be used for device  10  and/or device  10 ′ if desired. The example of  FIG. 1  is merely illustrative. 
     Electronic device  10  may have control circuitry  12 . Control circuitry  12  may include storage and processing circuitry for supporting the operation of device  10 . The storage and processing circuitry may include storage such as hard disk drive storage, nonvolatile memory (e.g., flash memory or other electrically-programmable-read-only memory configured to form a solid state drive), volatile memory (e.g., static or dynamic random-access-memory), etc. Processing circuitry in control circuitry  12  may be used to control the operation of device  10 . The processing circuitry may be based on one or more microprocessors, microcontrollers, digital signal processors, baseband processors, power management units, audio chips, application specific integrated circuits, etc. 
     Input-output circuitry in device  10  such as input-output devices  14  may be used to allow data to be supplied to device  10  and to allow data to be provided from device  10  to external devices. Input-output devices  14  may include a display, buttons, joysticks, scrolling wheels, touch pads, key pads, keyboards, audio components such as microphones and speakers, tone generators, vibrators, cameras, sensors, light-emitting diodes and other status indicators, data ports, etc. Wireless circuitry in devices  14  may be used to transmit and receive radio-frequency wireless signals. Wireless circuitry may include antennas and radio-frequency transmitters and receivers operating in wireless local area network bands, cellular telephone bands, and other wireless communications bands. 
     A user can control the operation of device  10  by supplying commands through input-output devices  14  and may receive status information and other output from device  10  using the output resources of input-output devices  14 . Control circuitry  12  may be used to run software on device  10  such as operating system code and applications. During operation of device  10 , the software running on control circuitry  12  may use input-output devices  14  to gather user input and other input and can provide the user with visual output, audio output, and other output. 
     Device  10 ′ may include the same circuitry as device  10  and/or may contain different circuitry. Devices  10  and  10 ′ may include respective connections  16  and  16 ′ and signal paths such as path  18 . Connections  16  and  16 ′ may be formed using solder, conductive adhesive, welds, connectors, and/or other structures for forming electrical and/or mechanical structures. Path  18  may be used to share input and output information between devices  10  and  10 ′. Portions of paths such as path  18  may be included in devices  10  and/or  10 ′. 
     Devices such as devices  10  and  10 ′ may be used together. For example, the input resource of the input-output devices in device  10 ′ may be used to gather input from a user. This user input may then be conveyed to device  10  over signal path  18  for use in controlling the operation of device  10 . If, for example, device  10 ′ includes a keyboard, a user may supply key press input to device  10 ′ that is conveyed via path  18  (e.g., a path that is separate from device  10 ′ and/or that is included in device  10 ′) to device  10 . Device  10  may also use the resources of device  10 ′ to provide the user with output. For example, device  10  can supply output to device  10 ′ over path  18  that instructs device  10 ′ to turn on or off particular light-emitting diodes or other status indicators or that instructs device  10 ′ to provide other visual and/or audio output for the user. 
     Signal paths such as path  18  between devices  10  and  10 ′ and portions of signal paths such as path  18  that are contained within devices  10  and  10 ′ may be formed from flexible fabric layers. These fabric layers may accommodate bends (e.g., tight bends) in the structures that make up devices  10  and/or  10 ′ and may facilitate concealment of the signal paths (e.g., to enhance device aesthetics in a device with a thin and flexible outer housing). 
     A perspective view of an illustrative device of the type that may be provided with a flexible fabric signal path is shown in  FIG. 2 . As shown in  FIG. 2 , device  10 ′ may be a flexible cover that can be used to protect an electronic device such as a tablet computer or other computing device. Device  10 ′ (sometimes referred to herein as cover  10 ′) may include body  20 . Body  20  may have surfaces formed from plastic, fabric, microfiber embedded in a polymer layer, or other suitable materials. For example, one side of body  20  (e.g., the exterior of body  20  when cover  10 ′ is closed around device  10 ) may be formed from a sheet of polymer and the other side of body  20  (e.g., the inner surface of body  20 ) may be formed from a microfiber layer. 
     Cover  10 ′ may include input-output components such as keyboard  26 , a touch pad (trackpad) that gathers touch and/or force input, and/or other input-output devices. Keyboard  26  may include keys  28 . Keyboard  26  may be mounted in lower portion  20 A of cover  10 ′. Upper portion  20 B of cover  10 ′ may contain foldable sections (horizontal strips) such as sections  22 . Sections  22  may bend about one or more bend axes such as bend axes  24 . 
     Upper portion  20 B may have a connector such as connector  16 ′. Connector  16 ′ may mate with a connector such as connector  16  that is associated with device  10  (i.e., when device  10  is mated with cover  10 ′). Connector  16 ′ may contain electrical contacts for coupling to corresponding connector contacts in connector  16 . These contacts may be electrically coupled to electrical components in lower portion  20 A such as keyboard  26  (e.g., one or more integrated circuits for gathering keystroke information during the operation of keys  28  in keyboard  26 ). 
     To accommodate bending of housing  20  about bend axes  24 , housing  20  may be provided with flexible hinge portions along the boundaries between sections  22  (i.e., along axes  24 ). A signal path for coupling connector  16 ′ to circuitry in keyboard  26  may run across axes  24  (i.e., the signal path may cross each of axes  24  at a right angle so as to extend between connector  16 ′ and keyboard  26 ). Because the signal path overlaps bend axes  24 , the signal path is preferably formed from a flexible signal path structure. With one suitable arrangement, the flexible signal path structure may be formed from a flexible fabric signal path structure having metal traces on a flexible fabric substrate or having conductive strands of material that are formed as part of the flexible fabric substrate. 
     A cross-sectional side view of cover  10 ′ and an associated device such as device  10  is shown in  FIG. 3 . As shown in  FIG. 3 , cover  10 ′ may be folded along bend axes  24  to form a stand for device  10 . Device  10  may have a housing such as housing  30  and a display such as display  32  that is mounted in housing  30 . Cover  10 ′ may support device  10  in a position that allows display  32  to be easily viewed by a user while the user is typing on keyboard  26 . When device  10  is supported by cover  10 ′, connector  16  of device  10  may mate with connector  16 ′ of cover  10 ′. Cover  10 ′ may bend along axis such as axis  24  and/or other bend axes that span the width of cover  10 ′. 
     As shown in the illustrative cross-sectional side view of cover  10 ′ of  FIG. 4 , cover  10 ′ may have stiffeners such as fiberglass stiffeners  34  (e.g., stiff rectangular panels of material). Flexible fabric signal path structure  36  may have ends  36 E that are coupled between connector  16 ′ and printed circuit  38 . Printed circuit  38  may be located in lower body portion  20 A of body  20  and may contain circuitry for controlling the operation of keyboard  26  (e.g., key switches, integrated circuits, signal traces, etc.). Flexible fabric signal path structure  36  may span locally thinned portions of body  20  that serve as hinges along bend axes  24 . 
     Fabric structure  36  may include one or more signal paths. In configurations in which structure  36  contains multiple signal paths, the signal paths may be formed from a series of parallel metal traces that run along the length of fabric structure  36  (i.e., between connector  16 ′ and printed circuit  38 ) and that serve as a signal bus. Analog and/or digital signals may be conveyed along this type of signal bus. There may be any suitable number of metal lines in a signal bus on fabric structure  36  (e.g., more than one, two, three, three or more, four or more, 10 or more, 10-20, 10-100, more than 50, less than 200, less than five, or other suitable number). 
     A perspective view of an illustrative three-wire signal bus formed from metal traces on flexible fabric structure  36  is shown in  FIG. 5 . As shown in  FIG. 5 , fabric structure  36  may have a fabric substrate such as substrate  40  and metal traces  42 . There are three metal traces  42  in  FIG. 5 , but more metal traces  42  or fewer metal traces  42  may be formed, if desired. As shown by illustrative bend axis  24 , metal traces  42  may be elongated traces that run perpendicular to bend axis  24  and that overlap bend axis  24  (and, if desired, multiple bend axes  24 ). If desired, metal traces  42  may include portions that intersect bend axis  24  at other angles, may include portions that run parallel to bend axis  24 , etc. 
     Traces  42  may be used for handling any suitable digital and/or analog signals. With one suitable arrangement, the centermost one of the three traces  42  of  FIG. 5  may be a data trace and the flanking outer traces on the left and right of the center trace may be ground traces (as an example). The center trace may have a width W 4  and the outer traces may have respective widths W 6  and W 2 . Trace-free portions of fabric substrate  40  may have respective widths of W 7 , W 5 , W 3 , and W 1 . The values of W 1 , W 2 , W 3 , W 4 , W 5 , W 6 , and W 7  may be 0.1 mm to 100 mm, may be 0.5 cm to 3 cm, may be 0.5-10 cm, may be more than 0.3 cm, may be more than 0.5 cm, may be more than 1 cm, may be 1-4 cm, may be 1-10 cm, may be more than 2 cm, may be less than 10 cm, may be less than 5 cm, may be less than 2 cm, or may be any other suitable widths. The use of relatively wide trace widths for traces  42  may help lower trace resistance. A large number of traces need not be used in scenarios in which the circuitry of cover  10 ′ does not need to communicate with device  10  over a wide bandwidth signal path (e.g., when only keystroke data and similar low-bandwidth data is transferred from cover  10 ′ to device  10 ). 
     Fabric for substrate  40  may be formed from intertwined strands of material such as strands  44  of  FIG. 6 . Strands  44  may be formed from dielectric material such as polymer and/or conductive material such as metal. For example, strands  44  may be formed from metal (e.g., metal wires), may be formed from polymer, may be formed from polymer coated with metal, may be coated with insulation or may be free of insulating coatings, may be formed from monofilaments, may be formed from multiple filaments that are intertwined to form multi-filament strands, and/or may be formed from other suitable strands of material. Strands  44  may be processed using a resist print technique that selectively prevents the deposition of metal or other added material, may be selectively etched (e.g., to remove metal), may be etched by selectively activating metal etchant, may be processed to selectively activate catalyst so as to control the deposition of metal or other materials, or may be processed using other processing techniques. Strands  44  may be intertwined to form substrate  40  using weaving techniques, using knitting techniques, using braiding techniques, and/or using other fiber intertwining techniques (e.g., felt fabrication techniques). In the example of  FIG. 6 , fabric  40  has vertical strands of material and intertwined horizontal strands of material. The vertical strands of material may be warp fibers and the horizontal strands of material may be weft fibers (as an example). Fabric  40  may be a woven fabric having a plain weave, basket weave, a ripstop construction (e.g., a reinforced fabric construction in which strands of material of enhanced strength are interspersed with strands of material of normal strength to help prevent tears from propagating). With one suitable arrangement, fabric substrate  40  is a woven nylon ripstop fabric. Other types of fabric may be used in forming substrate  40  if desired. 
     Conductive signal paths in fabric structure  36  may be formed from conductive strands of material in fabric  40 , from metal that is coated onto portions of fabric  40 , or other suitable conductive paths. 
       FIG. 7  is a cross-sectional side view of fabric structure  36  in an illustrative configuration in which metal traces  42  have been formed by depositing and patterning metal onto fabric substrate  40 . In the example of  FIG. 7 , fabric  40  has openings  47  (e.g., openings between strands of material such as strands  44 ) that receive portions of inner metal layer  46  when metal layer  46  is deposited on substrate  40 . Due to the presence of openings  47 , metal layer  46  may penetrate through fabric  40 . Metal layer  47  may be formed on one side of fabric  40  or metal layer  47  may coat both the upper and opposing lower surfaces of fabric  40 . 
     Metal traces  42  may be formed from patterned portions of the deposited metal. The metal layer on fabric  40  may have one or more layers (e.g., layers such as layers  46 ,  48 , and  50  that have been formed using different deposition techniques and/or using different elemental or alloyed metals). As an example, inner metal layer  46  may be formed from a high conductivity metal such as electroless copper or electroless nickel. One or more additional layers such as layers  48  and  50  may be deposited on one or both sides of fabric  36  (e.g., on the top and/or bottom of layer  46 ). The additional layer(s) may be used to help protect layer  46  and/or to provide additional desirable qualities (strength, low resistance, adhesion, oxidation protection, solder compatibility, etc.). With one illustrative configuration, layers  48  and/or  50  may be formed from materials with a high conductivity such as electroless or electrolytic plated silver and/or other electroless and/or electrolytic plated metals such as copper or tin. Optional layer  50  (e.g., a layer of nickel) may be the outermost layer of metal traces  42  and may help make trace  42  solder compatible or may be omitted (in which case layer  48  may serve as the outermost metal layer). The illustrative structures shown in  FIG. 7  include metal trace layers for metal trace  42  that are on both the upper and lower surfaces of fabric  40 . This is merely illustrative. Some or all of the metal on fabric  40  such as metal layers  46 ,  48 , and/or  50  may be located on only one side of fabric  40  (i.e., structure  36  may include metal traces  42  that are primarily or exclusively formed on one of its two opposing surfaces). 
     It may be desirable to orient the strands of material in fabric substrate  40  at a non-zero angle with respect to bend axis  24  (e.g., a non-zero acute angle) to enhance reliability. As shown in the example of  FIG. 8 , strands  44  may be oriented at a non-zero angle A with respect to bend axis  24 . Angle A may be, for example, 3°, 0-10°, 1-10°, more than 2°, less than 20°, or other suitable angle. Traces  42  can also be locally widened to help accommodate bending. For example, traces  42  can be widened where traces  42  overlap bend axis  24  to help prevent crack-induced open circuits, as shown in  FIG. 9 .  FIG. 10  shows how strands  44  may run parallel (or perpendicular) to bend axis  24  except in a local region such as local region  52  where fabric  40  overlaps bend axis  24 . In region  52 , strands  44  may be oriented at a non-zero angle A with respect to bend axis  24 , as described in connection with  FIG. 8 . 
     As shown in  FIG. 11 , a signal path (metal path  42 ) in structure  36  may be formed from conductive metal strands of material (strands  44 C). Insulating fibers  44 I may prevent short circuits between different paths  42 . Conductive strands  44 C may be bare metal wires, may be polymer strands coated with metal (and optionally an outer insulating coating that can be selectively removed when forming connections with circuitry in devices  10  and/or  10 ′). 
       FIG. 12  is an illustrative side view of structures that may be used in forming a device (e.g., cover  10 ′) that includes fabric structure  36 . As shown in  FIG. 12 , connector  16 ′ may be coupled to fabric structure  36  using structures such as flexible printed circuit  54  (e.g., a printed circuit containing metal interconnect traces to which connector  16 ′ may be soldered) and conductive pressure sensitive adhesive  56  (which may couple the traces of printed circuit  54  to fabric structure  36 ). 
     Keyboard  26  may be coupled to fabric structure  36  at one of the ends of structure  36 . Keyboard  26  may include printed circuit  38 . Integrated circuit  66  and/or other circuitry may be mounted on printed circuit  38  to serve as control circuitry for controlling keyboard  26 . Integrated circuit  66  and/or other control circuitry on printed circuit  38  may gather keystroke data from the keys in keyboard  26  and may communicate this information to device  10  via printed circuit interconnects  64 , metal traces  42  in fabric structure  36 , and connector  16 ′. 
     The keys for keyboard  26  may be formed from an array of key switches  68  mounted on the upper surface of printed circuit  38 . Plastic key web  72  may have openings that receive key caps  70 . Key caps  70  may be aligned with respective key switches  68  to form the keys of keyboard  26 . Fabric cover  74  or other covering material may be used to cover the outer surface of keyboard  26 . Printed circuit  38  may be coupled to metal traces  42  in fabric structure  36  using adhesive layer  58 . Adhesive layer  58  may include conductive adhesive  62  surrounded by non-conducting (insulating) adhesive  60 .  FIG. 13  is a top view of fabric structure  36  showing how conductive adhesive  62  may form rectangular regions on fabric  40 . Conductive adhesive  62  may overlap the ends of traces  42  and may be surrounded by insulating adhesive  60 . 
       FIG. 14  shows how structure  36  may be coupled to printed circuit  38 . Printed circuit  38  may have metal contact pads  64 P that are shorted to traces  64  in printed circuit  38 . Fabric structure  36  may include fabric substrate  40 . Metal traces  42  may be formed on substrate  40 . A thin dielectric coating (i.e., a thin insulating polymer protective layer) may cover the surface of substrate  40  and metal traces  42 . Conductive adhesive  62  may be patterned in rectangles or other suitable shapes (see, e.g., conductive adhesive  62  of  FIG. 13 ) to overlap the ends of metal traces  42 . Insulating adhesive  60  may surround each rectangle of conductive adhesive  62 . When printed circuit  38  and fabric structure  36  are pressed together, metal particles  62 P in adhesive  62  may penetrate coating  76  and become shorted to traces  42 . Metal particles  62 P may also form electrical connections to pads  64 P, thereby shorting traces  42  to pads  62 P and electrically coupling printed circuit  38  to fabric structure  36 . 
     If desired, a set of interlocking structures of the type shown in  FIG. 15  may be used to help secure fabric structure  36  to printed circuit  38 . Printed circuit  38  (or other structure to which it is desired to attach fabric structure  36 ) may be provided with recesses and clamp structure  78  may be provided with mating protrusions. When structure  78  is attached to structure  38 , the protrusions on structures  78  may help hold portions of fabric structure  36  within the mating recesses of printed circuit  38 , thereby attaching structures  36  and printed circuit  38 . If desired, a configuration of the type shown in  FIG. 15  may be used in conjunction with the conductive adhesive structures of  FIG. 14 . Other types of clamps, clips, fasteners, adhesives, and attachment structures may also be used in securing fabric structure  36  to printed circuit  38  and/or other circuitry in cover  10 ′. The example of  FIG. 15  is merely illustrative. 
     As shown in  FIG. 16 , components such as electrical components  80  may be mounted to fabric structure  36 . For example, contacts on components  80  may be coupled to metal traces  42  in structure  36  using solder or conductive adhesive. Components  80  may include input-output devices and/or control circuitry (e.g., integrated circuits and other components of the type described in connection with circuitry  12  and devices  14  of  FIG. 1 ). Components  80  and structure  36  may be enclosed within body  20 . Optional stiffening members such as planar fiberglass member  34  of  FIG. 16  may be used to help prevent bending of fabric  36  in the vicinity of components  80 , thereby reducing the risk that components  80  might become dislodged from fabric  36 . 
     Illustrative operations involved in forming fabric structure  36  are shown in  FIG. 17 . Fabric substrate  40  may be formed from polymer strands of material (e.g., nylon) or other suitable material. These strands may be woven together or may be intertwined using braiding techniques, knitting techniques, or other fiber intertwining techniques. 
     Substrate  40  may be pretreated at step  100  using chemicals, light, mechanical treatment (e.g., abrasion), or other pretreatment operations to prepare substrate  40  for application of electroplating catalyst material. 
     At step  102 , catalyst (e.g., a metal seed layer) may be applied to fabric substrate layer  40  (e.g., using physical vapor deposition or other deposition techniques). 
     At step  104 , metal electroplating operations or other suitable metal growth operations may be used to deposit one or more metal layers on one or both sides of substrate  40 . As described in connection with  FIG. 7 , for example, metal layers  46 ,  48 , and  50  may be formed on substrate  40  using electroplating techniques. Some of metal  46  may penetrate through the spaces between strands of material  44  in fabric  40  (see, e.g., openings  47  of  FIG. 7 , through which some of metal  46  has penetrated). 
     At step  106 , the blanket metal film that has been formed from the deposited metal layer(s) on fabric  40  may be patterned to form metal traces  42 . With one suitable arrangement, a masking layer such as a layer of polymer may be deposited and patterned on top of the metal layers. The polymer may be deposited and patterned using screen printing, using ink-jet printing, using blanket deposition followed by light exposure and developing (e.g., the polymer may be a photoresist that is patterned using photolithographic techniques), or other techniques for forming patterned masks. Following formation of the polymer mask, wet and/or dry metal etching processes may be used to remove undesired portions of the deposited metal, thereby forming patterned metal traces  42 . The polymer mask may then be stripped. If desired, a thin dielectric layer may be deposited over the traces for environmental protection (see, e.g., layer  76  of  FIG. 14 ). 
     If desired, metal trace patterning may be accomplished by patterning the electroplating catalyst, as shown in  FIG. 18 . 
     At step  108 , a catalyst (e.g., a metal seed layer) may be deposited in a desired pattern on fabric substrate  40  (e.g., using physical vapor deposition through a shadow mask, using inkjet or screen printing, using blanket film deposition followed by photolithographic patterning, etc.). 
     At step  110 , electroplating operations may be performed to grow metal layer(s) such as layers  46 ,  48 , and  50  of  FIG. 7 . These metal layers will grow selectively in the areas where catalyst is present and will not grow where catalysis is not present, thereby forming patterned metal traces  42 . 
     An environmental protection layer such as layer  76  of  FIG. 14  may be formed over metal traces  42  at step  112 . 
     If desired, other patterning techniques (screen printing and/or inkjet printing of metal paint, spraying, dripping, etc.) may be used in forming metal traces  42  of desired patterns for fabric structure  36 . The techniques of  FIGS. 17 and 18  are merely illustrative. 
     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: 20180129
Publication Date: 20190723
Grant Date: 20190723
Priority Date: 20150902
Inventors: COUSINS, Benjamin A.
STIEHL, KURT R.
SMITH, SAMUEL G.
MAYER, KIRK M.
HEGDE, SIDDHARTHA
KUNA, MELODY
Assignee: APPLE INC
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Family ID: 56684228