PATENT DOCUMENT

Publication Number: US-10712773-B2
Application Number: US-201816153457-A
Country: US
Kind Code: B2

Title: Systems with low-friction matte flexible printed circuits

Abstract:
An electronic device may include flexible printed circuits. A flexible printed circuit may have metal traces supported by a polymer substrate. The flexible printed circuit may extend between an upper laptop computer housing and a lower laptop computer housing or other structures that move relative to each other in an electronic device. The flexible printed circuit may have a low-friction coating and a matte finish. The flexible printed circuit may have a fluoropolymer coating on the polymer substrate, a fluoropolymer coating on a matte coating on the polymer substrate, a fluoropolymer coating that includes a matting agent on the polymer substrate, a fluoropolymer layer or other polymer layer that is attached to the substrate with a layer of adhesive, a textured surface layer, and/or other structures that help provide the flexible printed circuit with desired physical properties and a desired appearance.

Claims:
What is claimed is: 
     
       1. An electronic device, comprising:
 a housing having an upper housing portion and a lower housing portion, wherein the housing has an opening between the upper housing portion and the lower housing portion; 
 a hinge that connects the upper housing portion to the lower housing portion; 
 first circuitry in the upper housing portion; 
 second circuitry in the lower housing portion; and 
 a flexible printed circuit that is coupled between the first circuitry in the upper housing portion and the second circuitry in the lower housing portion, wherein the flexible printed circuit has a first region with a low-friction hydrophobic coating and a second region with a matte coating, and wherein the matte region is exposed by the opening between the upper housing portion and the lower housing portion. 
 
     
     
       2. The electronic device defined in  claim 1  further comprising:
 a display in the upper housing portion, wherein the first circuitry is coupled to the display. 
 
     
     
       3. The electronic device defined in  claim 2  further comprising a keyboard in the lower housing portion, wherein the upper and lower housing portions are rotatable with respect to each other. 
     
     
       4. The electronic device defined in  claim 1  wherein the hydrophobic flexible printed circuit includes a polymer substrate and a hydrophobic layer on the polymer substrate. 
     
     
       5. The electronic device defined in  claim 4  wherein the hydrophobic layer comprises a fluoropolymer coating on the polymer substrate. 
     
     
       6. The electronic device defined in  claim 5  wherein the hydrophobic layer is characterized by a water contact angle of at least 130°. 
     
     
       7. The electronic device defined in  claim 4  wherein the hydrophobic layer comprises a fluoropolymer layer attached to the polymer substrate by a layer of adhesive. 
     
     
       8. The electronic device defined in  claim 7  wherein the fluoropolymer layer comprises a layer of textured black polytetrafluoroethylene. 
     
     
       9. The electronic device defined in  claim 4  wherein the hydrophobic layer comprises a fluoropolymer layer and wherein the flexible printed circuit further comprises a matte coating layer between the polymer substrate and the fluoropolymer layer. 
     
     
       10. The electronic device defined in  claim 4  wherein the hydrophobic layer comprises a fluoropolymer coating mixed with a matting agent and wherein the fluoropolymer coating mixed with the matting agent has a gloss value of less than 10 gloss units at 85°. 
     
     
       11. The electronic device defined in  claim 1  wherein the housing comprises a material selected from the group of materials consisting of: plastic, metal, fiber composites, glass, and ceramic. 
     
     
       12. Apparatus having an interior and an exterior, the apparatus comprising:
 a housing having an upper housing portion that contains a display and having a lower housing portion, wherein the upper housing portion has a curved surface in the interior; 
 first and second hinges that connect the upper housing portion to the lower housing portion, wherein the upper and lower housing portions are rotatable with respect to each other; 
 circuitry in the lower housing portion; and 
 a flexible printed circuit that is coupled between the circuitry in the lower housing portion and the display in the upper housing portion, wherein the flexible printed circuit has a low-friction region and a matte region, wherein the flexible printed circuit wraps around the curved surface of the upper housing portion, and wherein the low-friction region overlaps the curved surface when the device is in the open position. 
 
     
     
       13. The apparatus defined in  claim 12  wherein the housing comprises polymer. 
     
     
       14. The apparatus defined in  claim 12  wherein the housing comprises glass. 
     
     
       15. The apparatus defined in  claim 12  wherein the housing comprises fiber composites. 
     
     
       16. The apparatus defined in  claim 12  wherein the flexible printed circuit comprises a fluoropolymer layer having a matting agent and exhibiting a gloss value of less than 2 gloss units at 60°. 
     
     
       17. The apparatus defined in  claim 16  wherein the fluoropolymer layer has a water contact angle of at least 105°. 
     
     
       18. The apparatus defined in  claim 16  wherein the fluoropolymer layer has a water contact angle of at least 130°. 
     
     
       19. Apparatus, comprising:
 a housing having a first housing portion containing the first printed circuit and a second housing portion containing the second printed circuit, wherein the first and second housing portions are movable with respect to each other and wherein the housing comprises an opening between the first and second housing portions; 
 a first printed circuit; 
 a second printed circuit; and 
 a flexible printed circuit having hydrophobic and matte portions that is coupled between the first printed circuit and the second printed circuit, wherein the matte portion of the flexible printed circuit extends across the opening between the first and second housing portions. 
 
     
     
       20. The apparatus defined in  claim 19  further comprising:
 a housing having a first housing portion containing the first printed circuit and a second housing portion containing the second printed circuit, wherein the first and second housing portions are movable with respect to each other.

Description:
This application is a continuation of U.S. patent application Ser. No. 15/243,370, filed Aug. 22, 2016, which is hereby incorporated by reference herein in its entirety. This application claims the benefit of and claims priority to U.S. patent application Ser. No. 15/243,370, filed Aug. 22, 2016. 
    
    
     FIELD 
     This relates generally to electronic devices and, more particularly, to flexible printed circuit structures coupled between components in electronic devices. 
     BACKGROUND 
     Electronic devices often include displays and other components. These components may sometimes be mounted in folding lids or other movable housings structures. A flexible printed circuit cable may be used to couple components together. For example, a flexible printed circuit cable may be used to couple a display in a laptop computer lid to a logic board in the main housing of the laptop computer. 
     If care is not taken, flexible printed circuits can be insufficiently robust to withstand repeated movement within a housing that has a movable lid or other movable structures, may be unsightly, or may be vulnerable to moisture exposure. 
     SUMMARY 
     An electronic device may include flexible printed circuits. A flexible printed circuit may have metal traces supported by a polymer substrate. The flexible printed circuit may traverse a gap between an upper laptop computer housing and a lower laptop computer housing or other structures that move relative to each other or may be used elsewhere in an electronic device. 
     The flexible printed circuit may have a low-friction coating that helps prevent sticking of the flexible printed circuit to structures in an electronic device such as movable housing structures. The low-friction coating may enhance moisture repellency (hydrophobicity). The flexible printed circuit may also have a matte finish such as a black matte finish to enhance the appearance of the flexible printed circuit. 
     The flexible printed circuit may have a fluoropolymer coating on a polymer substrate, a fluoropolymer coating on a matte coating on a polymer substrate, a polymer substrate with a fluoropolymer coating that includes a matting agent, a fluoropolymer layer or other polymer layer that is attached to a polymer substrate with a layer of adhesive, a textured surface layer, and other structures that help provide the flexible printed circuit with desired physical properties and a desired appearance. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an illustrative electronic device such as a laptop computer in accordance with an embodiment. 
         FIG. 2  is a cross-sectional side view of an illustrative electronic device such as a laptop computer with a flexible printed circuit in accordance with an embodiment. 
         FIG. 3  is a cross-sectional side view of an illustrative flexible printed circuit in accordance with an embodiment. 
         FIG. 4  is cross-sectional side view of an illustrative flexible printed circuit with a coating such as a fluoropolymer coating in accordance with an embodiment. 
         FIG. 5  is a cross-sectional side view of an illustrative flexible printed circuit with a matte coating layer and a fluoropolymer coating layer in accordance with an embodiment. 
         FIG. 6  is a cross-sectional side view of an illustrative flexible printed circuit with a matte fluoropolymer coating in accordance with an embodiment. 
         FIG. 7  is a cross-sectional side view of an illustrative flexible printed circuit to which a tape layer such as a textured black fluoropolymer tape layer has been attached using adhesive in accordance with an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Flexible printed circuits may be used to couple together circuitry in electronic devices and may be used as substrates to which integrated circuits and other components may be mounted. An electronic device of the type that may include one or more flexible printed circuits is shown in  FIG. 1 . Device  10  of  FIG. 1  may be a handheld electronic device such as a cellular telephone, media player, gaming device, or other device, may be a laptop computer, tablet computer, or other portable computer, may be a desktop computer, may be a computer display, may be a display containing an embedded computer, may be a television or set top box, or may be other electronic equipment. Configurations in which device  10  is a device such as a portable computer that has a lid that rotates relative to a base may sometimes be described herein as examples. This is, however, merely illustrative. Device  10  may be any suitable electronic equipment. 
     As shown in the example of  FIG. 1 , device  10  may have a housing such as housing  12 . Housing  12  may be formed from plastic, metal (e.g., aluminum), fiber composites such as carbon fiber, glass, ceramic, other materials, and combinations of these materials. Housing  12  or parts of housing  12  may be formed using a unibody construction in which housing structures are formed from an integrated piece of material. Multipart housing constructions may also be used in which housing  12  or parts of housing  12  are formed from frame structures, housing walls, and other components that are attached to each other using fasteners, adhesive, and other attachment mechanisms. 
     As shown in  FIG. 1 , device  10  may have input-output devices such as track pad  18  and keyboard  16 . Track pad  18  may be formed from a touch sensor that gathers touch input from a user&#39;s fingers. Keyboard  16  may have an array of keys  16 K that protrude through openings in the upper wall of housing  12 B. Device  10  may also have components such as a camera, microphones, speakers, buttons, status indicator lights, sensors, and other input-output devices. These devices may be used to gather input for device  10  and may be used to supply a user of device  10  with output. Ports in device  10  may receive mating connectors (e.g., an audio plug, a connector associated with a data cable such as a Universal Serial Bus cable, a data cable that handles video and audio data such as a cable that connects device  10  to a computer display, television, or other monitor, etc.). 
     Device  10  may include a display such a display  14 . Display  14  may be a liquid crystal display (LCD), a plasma display, an organic light-emitting diode (OLED) display, an electrophoretic display, or a display implemented using other display technologies. A touch sensor may be incorporated into display  14  (i.e., display  14  may be a touch screen display) or display  14  may be insensitive to touch. Touch sensors for display  14  may be resistive touch sensors, capacitive touch sensors, acoustic touch sensors, light-based touch sensors, force sensors, or touch sensors implemented using other touch technologies. 
     Device  10  may have a one-piece housing or a multi-piece housing. As shown in  FIG. 1 , for example, electronic device  10  may be a device such as a portable computer or other device that has a two-part housing formed from an upper housing portion such as upper housing  12 A and lower housing portion such as lower housing  12 B. Upper housing  12 A may include display  14  and may sometimes be referred to as a display housing or lid. Lower housing  12 B may sometimes be referred to as a base housing or main housing. 
     Housings  12 A and  12 B may be connected to each other using hinge structures located in region  20  along the upper edge of lower housing  12 B and the lower edge of upper housing  12 A. For example, housings  12 A and  12 B may be coupled using hinges  26 . Hinges  26  may be located at opposing left and right edges of housing  12  along hinge axis  22 . A slot-shaped opening such as opening (slot)  30  may be formed between upper housing  12 A and lower housing  12 B and may be bordered on either end by hinges  26 . Hinges  26  may allow upper housing  12 A to rotate about axis  22  in directions  24  relative to lower housing  12 B. The plane of lid (upper housing)  12 A and the plane of lower housing  12 B may be separated by an angle that varies between 0° when the lid is closed to 90°, 140°, or more when the lid is fully opened. 
     Devices such as device  10  of  FIG. 1  may include printed circuits. The printed circuits may contain signal paths formed from metal traces (e.g., traces of copper, gold, other metals, etc.) and insulating substrate layers. The printed circuits may include rigid printed circuit boards (e.g., printed circuits formed from fiberglass-filled epoxy or other rigid printed circuit board substrate material) and flexible printed circuits (e.g., printed circuits formed from flexible sheets of polymer such as layers of polyimide or other flexible polymer substrate material). Integrated circuits, connectors, discrete components (e.g., inductors, capacitors, and resistors), and other electrical components may be coupled to printed circuits such as flexible printed circuits (e.g., using conductive connections formed from solder, conductive adhesive, or other conductive material). Flexible printed circuits may also be used as signal paths for routing signals between different locations in an electronic device. For example, a flexible printed circuit such as flexible printed circuit  32  of  FIG. 1  may be used to route signals between display  14  and circuitry  34  across gap  30 . Circuitry  34  may include integrated circuits and/or other circuit components mounted to a logic board to which printed circuit  32  is coupled or integrated circuits and/or other circuit components mounted on an end portion of printed circuit  32  (e.g., circuitry  34  may include storage and processing circuitry such as a microprocessor, a graphics processing unit, and/or other circuitry for supporting the operation of device  10 ). Flexible printed circuit cables may be used to couple logic boards and other circuits to components such as touch sensors, may be used in interconnecting logic boards, may be used in routing signals between a logic board and a camera module or other components in device  10 , and/or may be used to convey signals between other circuitry in device  10 . 
     In some arrangements, printed circuits may be visible to a user of an electronic device and/or may experience repeated bending and unbending stress. Consider, as an example, the arrangement of  FIG. 1  in which flexible printed circuit  32  extends between upper housing  12 A and lower housing  12 B. A cross-sectional side view of a portion of device  10  of  FIG. 1  taken along line  40  and viewed in direction  42  is shown in  FIG. 2 . As shown in the illustrative cross-sectional side view of device  10  of  FIG. 2 , a viewer such as user  44  may view portion  32 P of flexible printed circuit  32  through housing openings such as gap  48  in direction  46  when upper housing  12 A is in an open position relative to lower housing  12 B (as an example). During use of device  10 , a user may open and close device  10  repeatedly. As upper housing  12 A is opened and closed (e.g., by rotating housing  12 A relative to housing  12 B in directions  24  relative to axis  22 ), flexible printed circuit  32  may be repeatedly bent back and forth. In an open configuration such as the illustrative configuration of  FIG. 2 , the surface of flexible printed circuit  32  that faces curved surface  12 AC of housing  12 A may be stretched against curved surface  12 AC. As a result, there is a risk that flexible printed circuit  32  will stick to surface  12 AC. 
     As a result of these concerns, it may be desirable to provide flexible printed circuit  32  with a number of enhanced visual and mechanical attributes. For example, it may be desirable to provide flexible printed circuit  32  with a matte appearance (e.g., a dark low gloss appearance) so that portion  32 P of flexible printed circuit is visually attractive (e.g., not too bright and shiny). To sustain repeated bending as housing  12  is opened and closed, it may be desirable to form flexible printed circuit  32  from structures that are sufficiently robust to withstand repeated flexing and possible punctures from external objects that protruded through openings such as opening  48 . To ensure that flexible printed circuit  32  does not stick to a surface such as surface  12 AC, it may be desirable to provide flexible printed circuit  32  with a low-friction surface that exhibits low adhesion to surface  12 AC. A surface such as a low-adhesion surface may be moisture repellant (e.g., flexible printed circuit  32  may be hydrophobic) and may therefore sometimes be referred to as a nonstick or hydrophobic surface. 
     A cross-sectional side view of an illustrative printed circuit of the type that may be provided with attributes such as these is shown in  FIG. 3 . A printed circuit for device  10  such as printed circuit  32  of  FIG. 3  may be a rigid printed circuit board, may be a rigid flex circuit that contains both rigid printed circuit board portions and flexible printed circuit portions, or may be a flexible printed circuit that does not include any rigid printed circuit board portions. Illustrative configurations in which printed circuit  32  is a flexible printed circuit without rigid portions may sometimes be described herein as an example. 
     As shown in  FIG. 3 , flexible printed circuit  32  may have a substrate such as substrate  50 . Substrate  50  may include one or more layers of polyimide or other flexible sheets of polymer material. These sheets of material may be laminated together using interposed layers of adhesive (as an example). Patterned metal traces  52  (e.g., lines, vias, and contact pads formed from copper and/or other metals) may be used to carry signals in flexible printed circuit  32 . For example, flexible printed circuit  32  may include metal traces such as solder pads  52 P to which connectors, integrated circuits, and other components  54  may be soldered (e.g., using mating solder pads  54 P on components  54  and solder  56 ). Conductive connections to traces  52  in flexible printed circuit  32  may also be made using conductive adhesive and/or other electrical coupling mechanisms. 
     There may be any suitable number of components  54  coupled to flexible printed circuit  32 . For example, flexible printed circuit  32  may be used solely as a signal bus cable and may have connectors mounted at each end and no intervening circuit components soldered to traces  52  along the length of flexible printed circuit  32 . As another example, flexible printed circuit  32  may be populated with 2-10, more than 3, fewer than 20 or other suitable number of electrical components (connectors, integrated circuits, discrete components, etc.). In some configurations, flexible printed circuit  32  may serve both as a component mounting substrate for integrated circuits (e.g., display driver circuitry, etc.) and as a cable (e.g., a cable that extends across an housing opening such as gap  30  of  FIG. 1 ). 
     Components  54  may, if desired, be mounted to both sides of flexible printed circuit  32  (e.g., both upper and lower surfaces of flexible printed circuit  32 ). Flexible printed circuit  32  may have an elongated outline (e.g., flexible printed circuit  32  may form an elongated strip) and/or may have a more compact (e.g., square) layout. Configurations in which flexible printed circuit  32  has a non-elongated portion and an elongated tail or tails extending outwardly from the non-elongated portion may also be used. 
     The upper and/or lower surfaces of flexible printed circuit  32  may be provided with coatings to enhance the performance of flexible printed circuit  32 . These coatings may, for example, improve the appearance of flexible printed circuit  32  by reducing the shininess (gloss) of flexible printed circuit  32  and/or may improve the mechanical properties of flexible printed circuit  32  (e.g., by reducing friction and therefore stickiness while increasing hydrophobicity, enhancing durability, etc.). As shown in the illustrative configuration of  FIG. 4 , flexible printed circuit  32  may have coatings such as layers  58  on substrate  50 . In general, coatings may be formed on one or both sides of flexible printed circuit  32 . In the example of  FIG. 4 , coating  58  has been formed on both the upper and lower surfaces of substrate  50 . In other examples (see, e.g.,  FIGS. 5, 6, and 7 ) layers have been formed on one side of substrate  50 . 
     Coating  58  of  FIG. 4  may be a low-friction coating (e.g., a coating that reduces the friction and adhesion properties of flexible printed circuit  32  relative to that of substrate  50 ). Low friction may generally be correlated with low stickiness (low adhesion) and hydrophobicity. Accordingly, it may be desirable for coating  58  to exhibit enhanced hydrophobicity. The amount of hydrophobicity of flexible printed circuit  32  may be quantified in terms of water contact angle. As an example, substrate  50  may be characterized by a water contact angle of 81° to 95° without any coatings (i.e., substrate  50  may not be hydrophobic when uncoated). To ensure that flexible printed circuit  32  is hydrophobic (e.g., to raise the water contact angle of flexible printed circuit  32  above 100°), coating  58  may be formed on substrate  50 . Coating  58  may be, for example, a fluoropolymer coating. An example of a fluoropolymer coating is perfluoropolyether. Other fluoropolymers that enhance the hydrophobicity of printed circuit  32  may be used, if desired. The resulting water contact angle of flexible printed circuit  32  of  FIG. 4  when coating  58  is formed on substrate  50  may be at least 100°, at least 105°, at least 110°, or other elevated value. In general, low-friction hydrophobic coatings for printed circuit  32  such as coating  58  may be formed from oil, dry lubricants, silicone spray coatings, or any other non-stick materials. 
     The surface of substrate  50  may have an associated gloss value. For example, a non-matte polyimide substrate  50  may have a gloss value of 25 gloss units at 60° and a gloss value of 43 gloss units at 85° (and a water contact angle of 81°) when substrate  50  is uncoated or may have a gloss value of 10 gloss units at 60° and a gloss value of 27 units at 85° when substrate  50  is uncoated and a matte uncoated polymer substrate  50  may have a gloss value of 3 gloss units at 60° and 28 gloss units at 85° (and a water contact angle of 95°) when uncoated. 
     The appearance of flexible printed circuit  32  may be enhanced by reducing the shininess and brightness of flexible printed circuit  32  (e.g., by lowering the gloss value of printed circuit  32  and/or by forming a dark surface for printed circuit  32 ). With one illustrative configuration, a matte coating (e.g., a black matte coating) may be incorporated into flexible printed circuit  32 . As shown in  FIG. 5 , for example, matte coating layer  60  may be formed on the surface of substrate  50  (e.g., a polyimide layer). Matte coating layer  60  may be uncovered by additional coating layers or may, as shown in  FIG. 5 , be coated with a low-friction coating such as fluoropolymer layer  58  to enhance hydrophobicity. Matte coating layer  60  may be formed from a polymer (e.g., epoxy, etc.) that includes light-absorbing pigment for reducing the brightness of layer  60  and that includes matting agents such as light-scattering particles that enhance the surface roughness of layer  60  and/or otherwise reducing the gloss value of flexible printed circuit  32 . For example, flexible printed circuit  32  of  FIG. 5  may be characterized by a gloss value of less than 18 gloss units (or less than 25 GU, less than 20 GU, or other suitable value) at 60° and may be characterized by a gloss value of less than 32 gloss units (or less than 43 GU, less than 40 GU, less than 35 GU, or other suitable value) at 85°. The color of layer  60  may be adjusted by incorporating black pigment or other colorant into layer  60  (e.g., so that layer  60  is matte black, etc.). The presence of layer  58  may help ensure that the water contact angle of flexible printed circuit  32  of  FIG. 5  is at least 105° or at least 100° (as examples). The presence of matte coating layer  60  may help ensure that the appearance of flexible printed circuit  32  is not too shiny. 
     Matte coating materials and fluoropolymer materials may be combined in a single coating layer (or multiple coatings) as shown by matte fluoropolymer coating layer  62  on substrate  50  in illustrative flexible printed circuit  32  of  FIG. 6 . With this type of arrangement, dark pigment, matting agents, light scattering particles, and/or other materials for reducing the gloss of flexible printed circuit  32  may be combined and used in forming a fluoropolymer layer such as layer  62  on substrate  50 . This may provide flexible printed circuit  32  with a gloss of 1 gloss unit (or less than 25 GU, less than 20 GU, less than 10 GU, less than 5 GU, or other suitable value) at 60° and a gloss value of 3-6 gloss units (or less than 43 GU, less than 25 GU, less than 20 GU, less than 10 GU, less than 5 GU, or other suitable value) at 85° (as an example). If desired, flexible printed circuit  32  of  FIG. 6  may be textured (e.g., using the matting agents in layer  62  and/or by using a texturing drum or other equipment to impart a texture to the surface of layer  62 ). The texturing of layer  62  and/or the inclusion of matting agents into layer  62  may enhance hydrophobicity for flexible printed circuit  32  of  FIG. 6 . For example, the water contact angle of flexible printed circuit  32  of  FIG. 6  may be enhanced to a value of at least 100°, at least 110°, at least 120°, at least 130°, at least 140°, or at least 150°. For at least some of these values (e.g., 150°), flexible printed circuit  32  will exhibit extreme hydrophobicity, low friction, and lack of stickiness that help prevent flexible printed circuit  32  from adhering to housing structures in device  10 , etc. The ability to repel moisture from flexible printed circuit  32  may also help prevent moisture damage in device  10 . 
     If desired, a layer of polymer may be attached to substrate  50  using adhesive. The added layer may provide enhanced robustness, hydrophobicity, opacity, low gloss, and/or other desired attributes. In the illustrative configuration of  FIG. 7 , a textured hydrophobic sheet (layer  64 ) has been attached to substrate  50  by an interposed layer of adhesive  66  (e.g., a layer of pressure sensitive adhesive or other adhesive). Layer  64  may be textured by processing the surface of layer  64  with a textured drum or using other layer texturing techniques to help enhance hydrophobicity and/or reduce gloss or, if desired, layer  64  may have an untextured surface. Layer  64  may be formed from a fluoropolymer such as polytetrafluoroethylene (as an example) to enhance hydrophobicity. Pigment may, if desired, be incorporated into layer  64  and/or matting agent may be incorporated into layer  64  to adjust the appearance of layer  64  (e.g., black pigment, matting agent to reduce the glass of layer  64 , etc.). With one illustrative configuration, layer  64  and layer  66  form a tape layer (e.g., a black polytetrafluoroethylene tape layer with or without texture) and may be attached to layer  50  by lamination. The thickness of this tape layer may be 10-150 microns, more than 5 microns, less than 100 microns, or other suitable thickness. The tape layer attached to layer  50  may be formed along only part of the length of flexible printed circuit  32  (e.g., visible portions, portions that bend and/or that are visible to a user such as portion  32 P of  FIG. 2 ) and/or the tape layer may be formed over the entire surface of flexible printed circuit  32 . If desired, the tape layer may be formed from a length of flexible printed circuit  32  (e.g., a printed circuit with metal traces, hydrophobic surfaces, matte surfaces, etc.). 
     The coating arrangements of  FIGS. 4, 5, 6, 7  may be used to cover one surface or both upper and lower surfaces of flexible printed circuit  32 . Moreover, polymer tape layers such as layer  64  of  FIG. 7  may be formed using a single layer of a fluoropolymer (e.g., layer  58  of  FIG. 4 ), using a matte coating such as coating  60  of  FIG. 5  that is optionally coated with layer  58 , using a matte fluoropolymer layer such as layer  62  of  FIG. 6 , using a drum-textured or other textured polymer layer (e.g., a black fluoropolymer layer such as a polytetrafluoroethylene layer or other layer that contains optional matting agent and that is optionally attached to substrate  50  with a layer of pressure sensitive adhesive or other adhesive), and/or using other suitable structures for reducing gloss, enhancing opacity (enhancing blackness and thereby reducing visibility), enhancing hydrophobicity (lowering adhesion and friction), and/or enhancing strength (robustness during bending, resistance to punctures, etc.). The configurations of  FIGS. 4, 5, 6 , and  7  are merely illustrative. The surfaces of flexible printed circuit  32  may be hydrophobic (e.g., the water contact angle of printed circuit  32  may be at least 100°, at least 110°, at least 130°, at least 150°, or other suitable value) and/or may exhibit low gloss (e.g., a gloss at 60° and/or 85° of less than 10 gloss units, less than 5 gloss units, less than 3 gloss units, less than 2 gloss units, less than 1 gloss unit, etc.). 
     The foregoing is merely illustrative and various modifications can be made to the described embodiments. The foregoing embodiments may be implemented individually or in any combination.

Metadata:
Filing Date: 20181005
Publication Date: 20200714
Grant Date: 20200714
Priority Date: 20160822
Inventors: POSNER, BRYAN W.
GARELLI, ADAM T.
Assignee: APPLE INC
CPC Classifications: [{"code": "H05K2203/1173", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F1/1683", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K2201/015", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K3/285", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F1/1616", "inventive": true, "first": true, "tree": "[]"}, {"code": "G06F1/1681", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K2201/015", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K1/0281", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K1/0281", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F1/1616", "inventive": true, "first": true, "tree": "[]"}, {"code": "H05K3/285", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K2203/1173", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F1/1683", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F1/1681", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F1/1683", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K3/285", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K2203/1173", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K2201/015", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K1/0281", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F1/1616", "inventive": true, "first": true, "tree": "[]"}]
Family ID: 61191517