PATENT DOCUMENT

Publication Number: US-9223424-B2
Application Number: US-201313858746-A
Country: US
Kind Code: B2

Title: Electronic device signal routing structures with conductive adhesive

Abstract:
An electronic device may have structures that are coupled together using conductive adhesive such as anisotropic conductive film and other adhesives. The structures that are coupled together may include a touch sensor structure formed from electrodes on the inner surface of a display cover layer, a display module having display layers such as a thin-film transistor layer, and circuitry mounted on substrates such as printed circuits. Conductive signal path structures may be used in routing signals within the electronic device. The conductive signal path structures may be formed from pins that are embedded within injection molded plastic, from metal traces such as laser-deposited metal traces that are formed on the surface of a plastic member or other dielectric, from metal structures that run within channels in a plastic, printed circuit traces, and other signal path structures.

Claims:
What is claimed is: 
     
       1. An apparatus, comprising:
 signal path structures having metal structures that convey signals and a rigid plastic member that supports the metal structures; 
 a display layer having metal traces coupled to the metal structures with anisotropic conductive film; 
 a printed circuit; 
 conductive traces in the printed circuit that are coupled to the metal structures with anisotropic conductive film; and 
 a light guide plate that is mounted on and supported by the rigid plastic member. 
 
     
     
       2. The apparatus defined in  claim 1  wherein the rigid plastic member comprises a plastic display chassis. 
     
     
       3. The apparatus defined in  claim 2 , wherein the plastic display chassis is a rectangular ring-shaped plastic display chassis. 
     
     
       4. The apparatus defined in  claim 3 , wherein the rectangular ring-shaped plastic display chassis has a first portion that extends parallel to the light guide plate, a second portion that extends parallel to the light guide plate, and a third portion that is perpendicular to the first and second portions. 
     
     
       5. The apparatus defined in  claim 2 , further comprising a reflective layer that is mounted on and supported by the rigid plastic member. 
     
     
       6. The apparatus defined in  claim 1  wherein the display layer comprises a thin-film transistor substrate layer. 
     
     
       7. The apparatus defined in  claim 6  further comprising a touch sensor having capacitive touch sensor electrodes coupled to at least some of the metal structures in the signal path structures with anisotropic conductive film. 
     
     
       8. The apparatus defined in  claim 7  further comprising:
 components mounted on the printed circuit. 
 
     
     
       9. The apparatus defined in  claim 1  wherein the rigid plastic member comprises injection molded plastic and wherein the metal structures comprise metal pins that are at least partly embedded within the injection molded plastic, the apparatus further comprising a touch sensor coupled to the metal pins. 
     
     
       10. An apparatus, comprising:
 a display cover layer; 
 touch sensor electrodes on the display cover layer; 
 signal path structures including a rigid plastic member and metal structures supported by the rigid plastic member; 
 a layer of anisotropic conductive film that electrically couples the metal structures to the touch sensor electrodes and that attaches the rigid plastic member to the display cover layer; and 
 a metal member with first and second opposing surfaces and an opening that extends from the first surface to the second surface, wherein the rigid plastic member comprises injection molded plastic that fills the opening, wherein the injection molded plastic that fills the opening has first and second opposing surfaces, and wherein the metal structures comprise metal bars that extend through the injection molded plastic from the first surface of the injection molded plastic to the second surface of the injection molded plastic. 
 
     
     
       11. The apparatus defined in  claim 10  further comprising a plastic block with metal members, wherein the plastic block with metal members are formed separately from the signal path structures, wherein each metal member of the plastic block is electrically coupled to a respective one of the metal bars through an additional layer of anisotropic conductive film. 
     
     
       12. An apparatus, comprising:
 a plastic display chassis; 
 a display backlight that includes a light guide plate, wherein the light guide plate is mounted on the plastic display chassis, and wherein the plastic display chassis comprises metal structures that convey signals and a rigid plastic member that supports the metal structures; 
 a display layer having metal traces coupled to the metal structures with anisotropic conductive film; 
 a printed circuit; and 
 conductive traces in the printed circuit that are coupled to the metal structures with anisotropic conductive film. 
 
     
     
       13. The apparatus defined in  claim 12 , wherein the plastic display chassis comprises a first portion that extends parallel to the light guide plate, a second portion that extends parallel to the light guide plate, and a third portion that is perpendicular to the first and second portions. 
     
     
       14. The apparatus defined in  claim 13 , wherein the display layer having metal traces is coupled to the second portion of the plastic display chassis. 
     
     
       15. The apparatus defined in  claim 14 , wherein the conductive traces in the printed circuit are coupled to the first portion of the plastic display chassis, and wherein the light guide plate is mounted on the first portion of the plastic display chassis. 
     
     
       16. The apparatus defined in  claim 15 , wherein the third portion of the plastic display chassis connects the first portion to the second portion. 
     
     
       17. The apparatus defined in  claim 12 , wherein the metal structures comprise metal pins, and wherein the rigid plastic member comprises injection molded plastic that surrounds at least some of the metal pins. 
     
     
       18. The apparatus defined in  claim 12 , wherein the metal structures comprise metal traces on at least one surface of the rigid plastic member. 
     
     
       19. The apparatus defined in  claim 12  wherein the metal structures include at least one branching metal structure having multiple branches that merge into a single branch. 
     
     
       20. The apparatus defined in  claim 12  wherein the rigid plastic member has channels that receive the metal structures. 
     
     
       21. The apparatus defined in  claim 12  wherein the rigid plastic member comprises injection molded plastic and wherein the metal structures comprise laser-deposited metal traces on the injection molded plastic. 
     
     
       22. The apparatus defined in  claim 12  further comprising an electrical component soldered directly to the metal structures.

Description:
BACKGROUND 
     This relates to electronic devices and, more particularly, to structures for routing signals within electronic devices. 
     Electronic devices such as cellular telephones and other portable devices have electrical components. Printed circuits and cables are used to route signals between the components. 
     In some devices, a conductive adhesive such as anisotropic conductive film is used in forming electrical connections between routing lines. Anisotropic conductive film can be highly conductive when activated by application of heat and pressure, but generally does not exhibit the same mechanical properties as other types of adhesive. For example, the impact resistance of anisotropic conductive film may be less than that of other adhesives, limiting the use of anisotropic conductive films in applications where impact resistance is needed. This can make it difficult to form signal routing paths that include anisotropic conductive film. If care is not taken, structures will not be adequately attached to each other and mechanical and electrical connections may not be satisfactory. Signal path layouts can also be constrained by the signal line substrates that are available for forming signals paths. 
     It would therefore be desirable to be able to provide improved structures for attaching device components together and for forming signal routing paths for an electronic device. 
     SUMMARY 
     An electronic device may have structures that are coupled together using conductive adhesive such as anisotropic conductive film and other adhesives. 
     The structures that are coupled together may include a touch sensor structure formed from electrodes on the inner surface of a display cover layer, a display module having display layers such as a thin-film transistor layer, and circuitry mounted on substrates such as printed circuits. 
     Conductive signal path structures may be used in routing signals within the electronic device. The conductive signal path structures may be formed from pins that are embedded within injection molded plastic, from metal traces such as laser-deposited metal traces that are formed on the surface of a plastic member or other dielectric, from metal structures that run within channels in a plastic member, from printed circuit traces, and from other metal structures supported by a plastic member or other dielectric. The plastic member may have a shape with a first portion that runs horizontally and a second portion that runs vertically, may have the shape of a plastic display chassis, or may have other shapes. A metal member such as a bracket may have an opening into which metal structures are mounted using injection molded plastic. Anisotropic conductive film may be used in coupling the metal structures in conductive signal path structures such as these to components such as touch sensor structures, display structures, and other circuitry. 
     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 front perspective view of an illustrative electronic device in accordance with an embodiment. 
         FIG. 2  is a cross-sectional side view of an illustrative electronic device in accordance with an embodiment. 
         FIG. 3A  is a cross-sectional side view of an uncompressed anisotropic film in accordance with an embodiment. 
         FIG. 3B  is a cross-sectional side view of the anisotropic conductive film following compression to form a conductive path in accordance with an embodiment. 
         FIG. 4  is a perspective view of an illustrative structure with metal strips embedded in a dielectric carrier for forming electrical signal paths in an electronic device in accordance with an embodiment. 
         FIG. 5  is an exploded perspective view of an illustrative structure with metal clips attached to a dielectric carrier for forming electrical signal paths in an electronic device in accordance with an embodiment. 
         FIG. 6  is a cross-sectional side view of a portion of an electronic device in which a signal path has been formed using a metal clip structure of the type shown in  FIG. 4  in accordance with an embodiment. 
         FIG. 7  is a cross-sectional side view of a portion of an electronic device in which a signal path structure has been formed using metal members embedded within a dielectric carrier such as an injection molded plastic member in accordance with an embodiment. 
         FIG. 8  is a diagram showing how signal path structures having metal members and a dielectric carrier of the type shown in  FIG. 7  may be formed in accordance with an embodiment. 
         FIG. 9  is a perspective view of operations and equipment involved in forming an illustrative metal member having an opening filled with dielectric and embedded metal bars that form signal paths in an electronic device in accordance with an embodiment. 
         FIG. 10  is a cross-sectional side view of a display having a metal member of the type shown in  FIG. 9  with that is used in forming a signal path coupled to a flexible printed circuit in accordance with an embodiment. 
         FIG. 11  is a cross-sectional side view of a display having a metal structure of the type shown in  FIG. 9  that is used in forming a signal path coupled to metal members such as metal bars embedded within a dielectric carrier such as an injection molded plastic member of the type shown in  FIG. 7  in accordance with an embodiment. 
         FIG. 12  is a top view of a housing structure having different regions covered with different types of adhesive in accordance with an embodiment. 
         FIG. 13  is a side view of illustrative signal path structures having a dielectric carrier supporting metal members with branching shapes for forming merging signal paths in accordance with an embodiment. 
         FIG. 14  is a perspective view of an illustrative dielectric carrier with channels or other regions that accommodate metal signal path structures such as metal pins in accordance with an embodiment. 
         FIG. 15  is a diagram showing how laser-based processing techniques may be used for activating selected portions of the surface of plastic carrier and depositing metal on the activated portions of the carrier to form desired patterned metal structures in accordance with an embodiment. 
         FIG. 16  is a cross-sectional side view of a portion of an electronic device in which a signal path has been formed using a plastic carrier with laser-patterned metal traces in accordance with an embodiment. 
         FIG. 17  is a cross-sectional side view of a portion of an electronic device in which a signal path has been formed using a plastic carrier with laser-patterned metal traces and in which an electronic component has been incorporated in accordance with an embodiment. 
         FIG. 18  is a cross-sectional side view of a system being used to form signal path structures based on a flexible printed circuit structure supported by upper and lower bent metal layers in an electronic device in accordance with an embodiment. 
         FIG. 19  is a cross-sectional side view of an electronic device in which an anisotropic conductive film bond and an adhesive layer are used in forming a layered structure including a flexible printed circuit layer in accordance with an embodiment. 
         FIG. 20  is a cross-sectional side view of a portion of an electronic device having a plastic display chassis structure that includes a signal path coupled to a touch sensor and traces in a thin-film transistor layer in a display in accordance with an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     An illustrative electronic device of the type that may be provided with electronic components and signal paths for routing signals between the electronic components is shown in  FIG. 1 . Device  10  of  FIG. 1  may be a handheld device such as a cellular telephone or media player, a tablet computer, a notebook computer, other portable computing equipment, a wearable or miniature device such as a wristwatch or pendant device, a television, a computer monitor, or other electronic equipment. 
     As shown in  FIG. 1 , electronic device  10  may include a display such as display  14 . Display  14  may be a touch screen that incorporates a layer of conductive capacitive touch sensor electrodes or other touch sensor components or may be a display that is not touch-sensitive. Display  14  may include an array of display pixels formed from liquid crystal display (LCD) components, an array of electrophoretic display pixels, an array of electrowetting display pixels, an array of organic light-emitting diode pixels, or display pixels based on other display technologies. 
     Display  14  may be protected using a display cover layer such as a layer of transparent glass or clear plastic. Openings may be formed in the display cover layer. For example, an opening may be formed in the display cover layer to accommodate buttons, speaker ports, and other components. Configurations of the type shown in  FIG. 1  in which display  14  is free of openings in the display cover layer may also be used, if desired. 
     Device  10  may have a housing such as housing  12 . Housing  12 , which may sometimes be referred to as an enclosure or case, may be formed of plastic, glass, ceramics, fiber composites, metal (e.g., stainless steel, aluminum, etc.), other suitable materials, or a combination of any two or more of these materials. 
     Housing  12  may be formed using a unibody configuration in which some or all of housing  12  is machined or molded as a single structure or may be formed using multiple structures (e.g., an internal frame structure, one or more structures that form exterior housing surfaces, etc.). Housing  12  may, if desired, have openings such as an opening to accommodate one or more buttons such as button  16  and one or more openings to form port  18  (e.g., a connector port, a speaker port, a microphone port, etc.). If desired, housing  12  may be free or nearly free of openings (e.g., in configurations in which device  10  receives and transmits signals wirelessly). 
     A cross-sectional side view of an illustrative electronic device is shown in  FIG. 2 . As shown in  FIG. 2 , electronic device housing  12  may have side housing walls such as walls  12 W and a planar rear wall such as wall  12 R. Other shapes may be used for housing  12  if desired. The configuration of  FIG. 2  is merely illustrative. 
     Display  14  may have a display module (sometimes referred to as display structures or display layers) such as display module  26 . Display module  26  may contain an array of display pixels such as liquid crystal display pixels, organic light-emitting diode display pixels, electrophoretic display pixels, or display pixels formed using other technologies. Adhesive  24  may be used to attach display module  26  to the underside (inner surface) of display cover layer  20 . 
     Display cover layer  20  may be formed from a clear layer of glass, a transparent plastic structure, or other transparent members. Display  14  may be a touch screen display that includes a touch sensor. The touch sensor may be formed from a touch sensor panel. The touch sensor panel may have array of capacitive touch sensor electrodes formed from a transparent conductive material such as indium tin oxide formed on a transparent polymer substrate layer. If desired, the touch sensor may be formed from an array of transparent conductive capacitive touch sensor electrodes such as touch sensor electrodes (touch sensor array)  22  of  FIG. 2  that are formed directly on the underside of display cover layer  20  (i.e., between adhesive  24  and display cover layer  20 ). 
     Device  10  may include one or more substrates such as substrate  32 . Substrates such as substrate  32  may include plastic carriers, printed circuit boards such as rigid printed circuit boards (e.g., boards formed from fiberglass-filled epoxy) and flexible printed circuits (e.g., printed circuits formed from flexible layers of polymer such as polyimide sheets with one or more layers of metal traces), or other dielectric substrate structures. One or more components such as components  34  may be mounted on the substrate structures. Components  34  may include integrated circuits, discrete components, batteries, display driver components, touch sensor processing circuits, switches, connectors, and other circuitry. As shown in  FIG. 2 , signal paths such as path  28  may be used to couple touch sensor layer  22  to the circuitry of components  34  on printed circuit  32 . Path  28  may include one or more metal lines that are coupled to traces  40  in substrate  32  using a connector such as connector  30  or other coupling mechanism. Signal paths such as path  36  may be used to couple display module  26  to the circuitry of components  34  on printed circuit  32 . Path  36  may include one or more metal lines that are coupled to traces  40  in substrate  32  using a connector such as connector  38  or other coupling mechanism. 
     Paths such a paths  28  and  36  and other signal paths in device  10  (e.g., the paths formed from printed circuit traces  40 ) may include one or more conductive signal lines. For example, these paths may contain numerous signal lines in parallel to form serial buses, parallel buses, and other signal paths that carry digital and/or analog signals. Path  28  may, for example, include multiple parallel metal lines for carrying touch sensor signals from touch sensor  22  to touch sensor processing circuitry on substrate  32 . Path  36  may contain multiple parallel metal lines for carrying display signals from components on substrate  32  to display module  26 . 
     Within the signal paths of device  10 , it may be desirable to form connections between two different conductive parts. For example, it may be desirable to couple conductive traces on one substrate such as indium tin oxide touch sensor traces, metal traces on a display, or other conductive traces to conductive structures on another substrate such as metal traces on a printed circuit or metal members in a connector. Conductive coupling structures in device  10  may be formed from connectors, welds, solder, conductive adhesive, and other conductive structures. As an example, conductive adhesive such as anisotropic conductive film may be used in forming conductive coupling structures. 
     Anisotropic conductive film may contain a heat activated adhesive material such as epoxy and conductive particles such as metal balls. A cross-sectional side view of an illustrative film is shown in  FIG. 3A . In the configuration of  FIG. 3A , anisotropic conductive film  42  is in an uncompressed state, so conductive particles  44  (e.g., metal balls or other metal particles) are suspended in adhesive  46  (e.g., heat activated epoxy) and are isolated from each other. Following compression under heat and pressure, metal particles  44  are shorted together and form conductive paths through film  42  in vertical dimension Z, as shown in  FIG. 3B . 
     If desired, conductive signal paths in device  10  may be formed using metal members such as metal bars or other conductive structures that are supported by an injection molded plastic carrier or other dielectric carrier. This type of configuration is shown in  FIG. 4 . As shown in  FIG. 4 , conductive signal path structures  48  include metal members  50  that are supported by dielectric material  52 . Metal members  50  may be metal bars, strips of metal, or other conductive structures. Dielectric support material  52  may be a rigid dielectric such as rigid injection-molded plastic. Metal members  50  of  FIG. 4  may pass though then entire body of support structure  52  or may be wrapped around the exterior of support structure  52 . In a typical configuration, each of metal members  50  is electrically isolated from the other metal members  50  in structure  48 . Configurations in which two or more of metal members  50  are shorted together may also be used, if desired. In the illustrative configuration of  FIG. 5 , metal members  50  have been formed from C-shaped strips of metal that clamp onto the exterior of support structure  52  in respective grooves  54 . 
       FIG. 6  is a cross-sectional side view of a portion of device  10  in which signal path structures such as structures  48  have been used in forming signal paths for display  14 . In particular, a conductive adhesive such as anisotropic conductive film  42  has been interposed between the conductive traces of touch sensor layer  22  and conductive metal members  50  on dielectric support structures  52  of signal path structures  48 . Metal members  50  may be coupled to traces  40  on substrate  32  using solder, anisotropic conductive film or other conductive adhesive, welds, connectors such as connector  30 , or other conductive structures. 
     The use of signal path structures  48  in forming conductive paths between the capacitive touch sensor electrodes of touch sensor  22  and traces  40  in printed circuit substrate  32  may help reduce the size of device  10  (e.g., by minimizing the size of the conductive paths to a size that is less than the size that would be consumed when using cables or other potentially bulky structures). As an example, conductive signal path structures  48  may be used in forming a conductive signal path with numerous parallel signal conductors that make a sharp right-angle bend between display  14  and the rest of device  10 . This sharp right-angle bend may consume less space than would be involved in accommodating a relatively large bend radius in a flexible printed circuit cable. In addition, some or all of width W of the upper surface of structures  48  may be covered with anisotropic conductive film  42 . This may maximize the mechanical support properties of the adhesive joint formed from anisotropic conductive film  42 . The joint formed from film  42  may, for example, be sufficiently robust to serve as the exclusive adhesive attachment between support structure  52  and display  14 , even though anisotropic conductive film sometimes does not exhibit the same amount of shock resistance as other adhesives. 
     As shown in  FIG. 7 , conductive signal path structures  48  may be formed by embedding elongated metal members  50  such as metal pins or other conductive structures within dielectric support structures  52 . Members  50  may be formed within dielectric support structures  52  by press fitting members  50  into a plastic carrier, by insert molding (e.g., by injection molding plastic  52  around members  50  in an injection molding tool), by attaching metal members  50  to a dielectric support structures  52  with adhesive, or by using other techniques for incorporating metal paths such as elongated metal structures  50  into structures  48 . 
     Structures  52  may be formed from plastic (e.g., rigid plastic) or other dielectric material. As shown in the cross-sectional side view of  FIG. 7 , portions of members  50  may be embedded within structures  52  and portions of members  50  may protrude from within structures  52  (e.g., so that these portions of members  50  lie on the surface of structures  52 ). 
       FIG. 8  is a diagram showing how signal path structures  48  of the type shown in  FIG. 7  may be formed. Initially, metal structures  50  may be formed (e.g., by die cutting, by stamping a desired pattern into a metal foil, by machining, by casting members  50  from molten metal, or by otherwise forming elongated metal structures  50 ). Plastic  52  and members  50  may be placed within a die cavity in insert molding tool  56 . Under heat and pressure, plastic  52  may be injection molded around some or all of members  50 , thereby forming signal path structures  48  in which members  50  are generally at least partly embedded within plastic  52  (e.g., rigid plastic). Using assembly equipment  58  (e.g., computer-controlled positioners, a heated bar for forming an anisotropic conductive film connection with anisotropic conductive film  42 , etc.), anisotropic conductive film  42  may be used to form an electrical connection between the capacitive touch sensor traces in touch sensor  22  and respective elongated metal structures (e.g., pins)  50  in conductive signal path structures  48 . As shown in  FIG. 8 , connector  30  or other conductive structures may be used in electrically coupling metal structures  50  to signal paths in printed circuit  32 . Structures  48  may have a horizontal portion (i.e., a portion in which plastic  52  extends parallel to display cover layer  20 ) and a vertical portion (i.e., a portion in which plastic  52  extends vertically downwards at a right angle to the horizontal portion and perpendicular to the plane of display cover layer  20 ). 
     As shown in  FIG. 9 , a metal bracket or other metal member such as metal housing frame member  60  or other metal structure may be provided with an opening such as opening  62 . Insert molding tool  56  (e.g., plastic injection molding equipment) may be used to injection mold plastic  52  and metal structures  50  (e.g., metal bars) into opening  62  of metal member  60 , thereby forming conductive signal path structures  48  in which metal bars  50  extend through injection molded plastic  52  in opening  62 . 
       FIG. 10  is a cross-sectional side view of conductive signal path structures such as structures  48  of  FIG. 10  in a portion of electronic device  10 . As shown in  FIG. 10 , display  14  may have a cover layer such as display cover layer  20 . Touch sensor  22  (e.g., a patterned array of conductive capacitive touch sensor electrodes such as indium tin oxide electrodes) may be formed on the underside of display cover layer  20 . Adhesive  24  may be used to attach display module  26  to display cover layer  20  in the center of display  14 . In a peripheral inactive border region of display  14 , conductive adhesive layers may be used to form conductive signal paths between the traces in touch sensor  22  and traces in flexible printed circuit  64 . For example, upper anisotropic conductive film layer  42 - 1  may be used in forming conductive paths between the traces of touch sensor  22  and respective metal bars  50  in structures  48 . Lower anisotropic conductive film layer  42 - 2  may be used in forming conductive paths between metal bars  50  and respective metal traces in flexible printed circuit  64 . Anisotropic film forms conductive paths upon application of sufficient heat and pressure. 
     To form multiple conductive paths in parallel, metal structures such as bars  50  may be formed with a thickness that is larger than the thickness of plastic  52 . During compression of films  42 - 1  and  42 - 2  (e.g., using a heated bar), conductive paths will form in films  42 - 1  and  42 - 2  wherever the films overlap bars  50  due to the additional thickness of bars  50  and the resulting additional pressure applied to the films by bars  50 . The portions of the anisotropic conductive film in less compressed regions will remain insulating so that all of the conductive paths in the anisotropic conductive film are not shorted together. 
     Metal structure  60  may be formed from a metal such as stainless steel (as an example) that allows the size (e.g., the thickness) of metal structure  60  to be minimized while providing structural strength for device  10 . Metal structure  60  may, for example, form an internal frame member (e.g., an internal housing member) for device  10 . If desired, other metals may be used (e.g., aluminum, etc.). The use of a metal such as stainless steel in forming metal member  60  in signal path structures  48  of  FIG. 10  is merely illustrative. 
       FIG. 11  is a cross-sectional side view of a portion of device  10  showing how a conductive path structure such as structure  48  of  FIG. 4  (shown as structure  48 ′ in  FIG. 11 ) may be used in device  10 . As shown in  FIG. 11 , structures  48  may include metal bars  50  in injection molded plastic  52  formed within an opening in metal member  60 . Structures  48 ′ may be formed from dielectric such as a block of injection molded plastic that includes embedded metal members (e.g., dielectric  52  and metal bars  50  of  FIG. 4 ). The embedded metal members may have exposed surfaces at the top and bottom of the plastic block. The exposed surfaces of the embedded metal members may each form an electrical contact with a respective one of metal bars  50  of  FIG. 11  using a respective compressed portion of interposed anisotropic conductive film  42 - 2 . 
     In structures such as the structures of  FIGS. 10 and 11 , the entire width of anisotropic conductive film  42 - 1  that is attached to the inner surface of display cover layer  20  helps form a mechanically sound bond between metal structure  60  and the other portions of structures  48  and display cover layer  20 . Because this entire width is available for forming the anisotropic conductive film bond, it may be possible to achieve a desired bond quality using anisotropic conductive film material, even though other adhesives may exhibit superior properties such as superior shock resistance per unit area. 
     If desired, the mechanical quality of the adhesive connections that are formed in device  10  can be enhanced while retaining desired conductive paths through anisotropic conductive film areas by using a combination of adhesive that has been formulated for its mechanical properties (sometimes referred to as mechanical adhesive) and anisotropic conductive film. As shown in the illustrative top view of device  10  in  FIG. 12 , for example, one edge segment of internal frame structure  60 F of device  10  such as portion  48 E may be covered with a layer of anisotropic conductive film to provide desired electrical connections between touch sensor traces and metal structures such as bars  50 , whereas other portions of structure  60 F such as portions  70  may be coated with mechanical adhesive (e.g., epoxy without metal particles, adhesive with elastomeric polymer components such as rubber particles for providing impact resistance qualities, etc.). As indicated by dashed line  72 , portions  70  may, if desired be extended to encircle some or all of area  48 E (e.g., so that mechanical adhesive can partly or completely surround anisotropic conductive film areas such as area  48 E to provide area  48 E with additional desired mechanical adhesive properties such as enhanced impact resistance). 
       FIG. 13  is a side view of structures  48  in a configuration in which multiple metal paths such as paths  50 - 1  and  50 - 2  merge at Y-junction  50 Y to form unified path  50 - 3 . With this type of branching signal path arrangement, multiple metal paths (e.g., two or more branch signal paths such as paths  50 - 1  and  50 - 2 ) may be joined to combine signals together (e.g., to short multiple signal lines to a common ground path or to a common signal line) or a single path may be split into multiple signal lines (e.g., to fan out signals among a group of signal lines). The metal paths of  FIG. 13  (e.g., paths  50 - 1 ,  50 - 2 ,  50 - 3 , and other paths  50 ) may be formed from metal pins or other metal members, from metal traces formed on the surface of dielectric  52 , from metal structures that are embedded within dielectric  52 , from metal structures in open channels within dielectric  52 , from metal foil or a stamped sheet of metal that is attached to the surface of dielectric  52 , or other metal structures. 
       FIG. 14  is an illustrative configuration in which metal structures  50  have been formed within open-topped channels  76  in dielectric  52 . Dielectric  52  may, if desired, surround metal structures  50  (i.e., metal structures  50  can be enclosed within dielectric  52  using an insert molding process or other fabrication techniques). As with the other configurations for dielectric  52  of structures  48 , plastic  52  (e.g., rigid injection molded plastic  52 ) of  FIG. 14  has one portion that extends parallel to the plane of display cover layer  20  (i.e., the upper horizontal portion of structures  48 ) and another portion that extends perpendicular to display cover layer  20  (i.e., the vertical portion of structures  48 ). This type of configuration may be used to route signals vertically downwards towards a printed circuit board without consuming excess space by using a curved surface following a large bend radius. 
       FIG. 15  is a diagram of illustrative laser-based equipment and laser-based processing operations that may be used to form laser-deposited metal traces such as metal structures  50  for conductive signal path structures  48 . As shown in  FIG. 15 , laser-based processing equipment  78  may include a computer-controlled positioner such as computer-controlled positioner  80  for controlling the position of laser  82 . Laser  82  emits laser beam  84 . Computer-controlled positioner  80  controls the position of laser beam  84  on the surface of dielectric  52  (e.g., rigid plastic such as plastic with metal particles or other material that can be selectively laser-activated by application of laser light). 
     Using computer-controlled positioner  80 , equipment  78  may apply laser light  84  in a desired pattern on the surface of dielectric  52 . The portions of dielectric  52  that are not exposed to light  84  will not be activated and will resist metal deposition during subsequent plating operations. The portions of dielectric  52  that are selectively activated by application of light  84  will promote metal formation during subsequent plating operations. 
     Following immersion in a metal plating bath or other plating process associated with plating equipment  86 , metal lines  50  may be grown in a pattern defined by the laser-activated regions on dielectric  52  to form structures  48 . Any suitable number of surfaces of dielectric  52  may be provided with metal traces  50  in this way. For example, edge portions of structures  48  may be plated by rotating dielectric  52  under laser beam  84 . 
     A cross-sectional side view of a portion of device  10  in the vicinity of structures  48  that have been formed using laser processing equipment of the type shown in  FIG. 15  is shown in  FIG. 16 . As shown in  FIG. 16 , structures  48  may have a dielectric support such as dielectric  52  (e.g., rigid injection-molded plastic). Metal traces  50  may be formed using laser processing equipment of the type described in connection with  FIG. 15 . Traces  50  may include individual signal paths and branching (merging) signal paths of the type described in connection with  FIG. 13 . Anisotropic conductive film  42  may be used to form electrical connections between each of multiple traces  50  on dielectric  52  and respective capacitive touch sensor electrodes in touch sensor layer  22  on the lower surface of display cover layer  20 . 
       FIG. 17  is a cross-sectional side view of a portion of device  10  in a configuration in which an electrical component such as component  88  has been mounted to traces  50 . As with the illustrative configuration of  FIG. 16 , structures  48  of  FIG. 17  may have a dielectric support such as dielectric  52  (e.g., rigid injection molded plastic). Metal traces  50  on dielectric  52  may be laser-deposited traces formed using laser processing equipment of the type described in connection with  FIG. 15 . Traces  50  may include individual signal paths and branching (merging) signal paths. Anisotropic conductive film  42  may be used to form electrical connections between each of multiple traces  50  on dielectric  52  and respective capacitive touch sensor electrodes in touch sensor layer  22  on the lower surface of display cover layer  20 . Connection structures  90  may be used in attaching one or more components such as component  88  to metal traces  50 . Connection structures  90  may be based on welds, solder joints, conductive adhesive, or other conductive materials. For example, component  88  may be an integrated circuit that is soldered to metal structures  50 . 
       FIG. 18  shows how a flexible printed circuit may be supported using metal sheets. Flexible printed circuit  90  may contain a dielectric substrate such as substrate  92  (e.g., a layer of polyimide or other flexible polymer sheet). One or more layers of patterned metal traces  94  may be formed within substrate  92 . Adhesive or other attachment mechanisms may be used to attach metal sheets  96  to one or both of the opposing upper and lower surfaces of flexible printed circuit  90 . Bending equipment  98  may bend flexible printed circuit  90  and metal support sheets  96  to form signal path structures  100  with a bend such as bend  102 . Bend  102  may be a right angle bend of the type shown in  FIG. 18  or may be characterized by an angle that is less than or greater than 90°. Due to the presence of metal sheets  96 , flexible printed circuit  90  may retain bend  102  and structures  100  may be sufficiently robust to serve as mechanical support structures (e.g. part of an internal housing frame, etc.) in device  10 . 
       FIG. 19  is a cross-sectional side view of device  10  in a configuration in which multiple layers of adhesive are being used to attach flexible printed circuit  110  within device  10 . Display  14  of device  10  is mounted in housing  12 . Display module  26  may be mounted to display cover layer in display  14  using adhesive layer  24 . Flexible printed circuit  110  has one or more layers of patterned metal traces  112  supported by a polyimide layer or other flexible polymer substrate (substrate  114 ). Structure  116  (e.g., an internal frame structure or other structure) may be mounted within interior  118  of housing  12 . Display  14  includes touch sensor  22  (e.g., capacitive touch sensor electrode traces such as patterned indium tin oxide traces on the lower surface of display cover layer  20 ). 
     Adhesive  42  may be interposed between the upper surface of flexible printed circuit  110  and the lower surface of display  14  (e.g., the lower surface of touch sensor  22  on the lower surface of display cover layer  20 ). Adhesive  42  may be a conductive adhesive such as anisotropic conductive film and may be used to make one or more electrical connections between flexible printed circuit  110  and touch sensor  22 . For example, anisotropic conductive film  42  may be used to couple each of multiple traces  112  in flexible printed circuit  110  to respective conductive traces in touch sensor  22  (e.g., respective indium tin oxide capacitive electrode traces in touch sensor  22 ). 
     Adhesive  120  may be interposed between the lower surface of flexible printed circuit  110  and the upper surface of support structure  116  (e.g., an internal housing frame, a portion of an external housing member, or other structure in device  10 ). Adhesive  120  may be formed from anisotropic conductive film, mechanical adhesive, or a mixture of anisotropic conductive film and mechanical adhesive. As an example, adhesive  120  may be formed from an adhesive material that includes shock-resistant filler such as elastomeric particles (e.g., rubber beads such as nitrile beads). The presence of nitrile beads or other elastomeric additive to adhesive  120  may help enhance the impact resistance and toughness of adhesive  120 , but may not be compatible with anisotropic conductive film formulations. Accordingly, the adhesive that is interposed between flexible printed circuit  110  and structures  116  (i.e., adhesive  120 ) may, if desired, be formed from adhesive that does not contain anisotropic conductive film particles (i.e., an adhesive that is free of anisotropic conductive film metal balls). 
     With a configuration of the type shown in  FIG. 19 , flexible printed circuit  110  is sandwiched between two adhesive layers. Layer  42  may be an anisotropic conductive film that forms conductive paths between traces  112  and corresponding traces in touch sensor  22 . Layer  120  may be an adhesive that provides shock resistance to the stack-up formed by the adhesive layers. Because the portion of flexible printed circuit  110  that is sandwiched between structures  116  and display  14  is supported by both adhesive layer  120  and layer  42 , layer  120  can enhance the mechanical strength and impact resistance of the adhesive connection between flexible printed circuit  110  and the other structures of device  10  (i.e., the mechanical adhesive properties of layer  120  can supplement the adhesive properties of layer  42 , which allows layer  42  to be formed from a material such as anisotropic conductive film that may have lower impact resistance than mechanical adhesive). 
     Although the structures of  FIG. 19  that are sandwiched between adhesive layers  42  and  120  in  FIG. 19  are formed from flexible printed circuit  110 , other structures (e.g., other substrate layers, other flexible layers, other polymer layers, or other sheets of material or structures) may be sandwiched between adhesive layers such as layers  42  and  120 , if desired. The configuration of  FIG. 19  is merely illustrative. 
     As shown in  FIG. 20 , device  10  may use conductive signal path structures  48  in connecting touch sensor structures  22  and/or display structures such as display structures in display module  26  to circuitry such as circuitry  34  on one or more substrates such as printed circuit  32 . Touch sensor structures  22  may be formed on the lower surface of display cover layer  20 . Conductive signal path structures  48  may be formed from dielectric  52  and conductive paths  50 . Dielectric  52  may be plastic such as rigid injection molded plastic or other dielectric. Conductive paths  50  may be formed from metal pins, from traces formed on surface regions in structures  48 , from patterned metal foil or a patterned metal sheet that is attached to a surface portion of dielectric  52 , or from other conductive structures. Anisotropic conductive film  42 A may be used to form electrical connections between conductive traces in touch sensor structures  22  and corresponding conductive paths  50  in structures  48 , so that signals can be routed between touch sensor structures  22  and circuitry  34  on printed circuit  32 . 
     Display layers associated with display module  26  may also be electrically coupled to printed circuit board  32  using conductive signal path structures  48 . Display module  26  may include layers such as layer  132  and layer  130 . Layer  132  may be a color filter layer. Layer  130  may be a thin-film transistor layer having a glass or plastic substrate that includes a layer of thin-film transistors (e.g., a thin-film transistor layer substrate layer in a liquid crystal display, etc.). Display driver integrated circuit  136  may be used in supplying signal lines  134  on thin-film transistor layer  130  with display data and control signals. Signal lines  134  (e.g., metal traces) may be used to route signals to and from thin-film circuitry and other components in layer  130 . Anisotropic conductive film  42 B may be used in coupling traces  134  to conductive signal paths  50  in structures  48 . Anisotropic conductive film  42 C may be used in coupling conductive paths  50  to traces  40  in printed circuit  32 . Traces  40  are also coupled to integrated circuits and other components  34  on printed circuit  32 . 
     Dielectric  52  may have an opening such as opening  138  to allow heated bar  140  to move in direction  142 . This allows heated bar  140  to be used to apply heat and pressure to films  42 A and  42 B to form satisfactory electrical and mechanical anisotropic conductive adhesive bonds. Components such as component  144  may be supported within the interior of device  10  using dielectric  52 . For example, dielectric  52  may have the shape of a rectangular ring-shaped plastic display chassis (sometimes referred to as a p-chassis). The p-chassis formed from plastic  52  may be used to support display layers such as backlight unit layers in a display backlight unit. Component  144  may, for example, include one or more display backlight components such as a light guide plate, a rear reflective layer, diffuser films, compensating films, prism films, and other layers associated with a backlight for display  14 . In this way, structures  48  may serve both as a support for conductive paths  50  and as a support for display structures such as component  144  (e.g., a backlight unit or other display layers). 
     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: 20130408
Publication Date: 20151229
Grant Date: 20151229
Priority Date: 20130408
Inventors: DE JONG ERIK G.
SHEDLETSKY ANNA-KATRINA
ROTHKOPF FLETCHER R.
Assignee: APPLE INC
CPC Classifications: [{"code": "G02F1/13452", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02F1/133608", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F3/041", "inventive": true, "first": true, "tree": "[]"}, {"code": "G02F1/13338", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02F1/133308", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F2203/04103", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02F1/13338", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F3/04164", "inventive": true, "first": true, "tree": "[]"}, {"code": "G06F3/041", "inventive": true, "first": true, "tree": "[]"}, {"code": "G02F1/13452", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F2203/04103", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02F1/133608", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F2203/04103", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02F1/133308", "inventive": false, "first": false, "tree": "[]"}]
Family ID: 51654199