PATENT DOCUMENT

Publication Number: US-10844524-B1
Application Number: US-201615146726-A
Country: US
Kind Code: B1

Title: Forming electrical connections in fabric-based items

Abstract:
An item may include fabric or other materials formed from intertwined strands of material. The item may include circuitry that produces signals. The strands of material may include non-conductive strands and conductive strands. The conductive strands may carry the signals produced by the circuitry. Each conductive strand may have a strand core, a conductive coating on the strand core, and an insulating layer on the conductive coating. The strand cores may be strands formed from polymer. The conductive coating may be formed from metal. Electrical connections may be made between intertwined conductive strands by selectively removing portions of the outer insulating layer to expose the conductive cores of overlapping conductive strands. A conductive material such as solder or conductive epoxy may be applied to the exposed portions of the conductive cores to electrically and mechanically connect the overlapping conductive strands.

Claims:
What is claimed is: 
     
       1. Intertwined strands of material, comprising:
 non-conductive strands; 
 first and second overlapping conductive strands that are intertwined with the non-conductive strands, wherein the first and second conductive strands each have an insulating coating formed on a conductive inner portion, wherein the conductive inner portions of the first and second conductive strands each have an exposed portion in a region, wherein the first conductive strand overlaps the second conductive strand, wherein the conductive inner portions of the first and second conductive strands each comprise a conductive coating formed on an outer surface of a dielectric core, and wherein the conductive coating and the dielectric core extend continuously through the region; 
 a conductive material that electrically connects the exposed portion of the conductive inner portion of the first conductive strand to the exposed portion of the conductive inner portion of the second conductive strand, wherein the conductive material is interposed between the exposed portion of the conductive inner portion of the first conductive strand and the exposed portion of the conductive inner portion of the second conductive strand; and 
 an encapsulation layer that seals the conductive material and the exposed portions of the conductive inner portions of the first and second conductive strands, wherein the encapsulation layer covers the first and second conductive strands in the region and the insulating coating on each conductive strand extends outside the region. 
 
     
     
       2. The intertwined strands of material defined in  claim 1  wherein the conductive coating comprises metal. 
     
     
       3. The intertwined strands of material defined in  claim 1  wherein the conductive coating comprises silver. 
     
     
       4. The intertwined strands of material defined in  claim 1  wherein the dielectric core comprises a polymer. 
     
     
       5. The intertwined strands of material defined in  claim 4  wherein the polymer is selected from the group consisting of: polyamide, aromatic polyamide, polyimide, polyester, polyolefin, acrylic, aromatic polyesters, polyethylene, cellulosic polymer, and polyurethane. 
     
     
       6. The intertwined strands of material defined in  claim 4  wherein the polymer is a para-aramid. 
     
     
       7. The intertwined strands of material defined in  claim 4  wherein the polymer is an aromatic polyester. 
     
     
       8. The intertwined strands of material defined in  claim 1  wherein the insulating coating comprises thermoset polyurethane. 
     
     
       9. The intertwined strands of material defined in  claim 1  wherein the conductive material comprises solder that mechanically and electrically connects the conductive inner portions of the first and second conductive strands. 
     
     
       10. The intertwined strands of material defined in  claim 1  wherein the conductive material comprises conductive epoxy that mechanically and electrically connects the conductive inner portions of the first and second conductive strands. 
     
     
       11. A fabric-based item, comprising:
 circuitry; and 
 intertwined strands of material including conductive strands that carry signals for the circuitry and non-conductive strands, wherein the conductive strands each have a polymer strand core, a metal coating on the polymer strand core, and an outer coating on the metal coating, wherein the outer coating of a first conductive strand in the conductive strands comprises an insulating portion that includes a dielectric material and a conductive portion that includes the dielectric material and a conductive material and wherein the conductive portion of the outer coating of the first conductive strand in the conductive strands forms an electrical connection between the first conductive strand and a second conductive strand in the conductive strands. 
 
     
     
       12. The fabric-based item defined in  claim 11  wherein the conductive material comprises conductive ink. 
     
     
       13. The fabric-based item defined in  claim 11  wherein the dielectric material comprises a material selected from the group consisting of: polyvinyl formal, polyester-polyimide, polyamide-polyimide, polyamide, polyimide, polyester, polytetrafluoroethylene, and polyurethane. 
     
     
       14. A fabric-based item, comprising:
 circuitry; and 
 intertwined strands, wherein the intertwined strands comprise:
 insulating strands; 
 a first conductive strand that has a first polymer strand core, a first metal coating on the polymer strand core that carries first signals for the circuitry, a first insulating coating on the first metal coating, and a metal coating shielding layer on the first insulating coating; and 
 a second conductive strand that has a second polymer strand core, a second metal coating on the polymer strand core that carries second signals for the circuitry, and a second insulating coating on the second metal coating, wherein the second conductive strand overlaps the first conductive strand. 
 
 
     
     
       15. The fabric-based item defined in  claim 14 , wherein the metal coating shielding layer is coaxial with the first metal coating. 
     
     
       16. The fabric-based item defined in  claim 14 , wherein the metal coating shielding layer forms a ground plane for an antenna. 
     
     
       17. The fabric-based item defined in  claim 14 , wherein the metal coating shielding layer is in contact with the second insulating coating. 
     
     
       18. The intertwined strands of material defined in  claim 1  wherein the insulating coating comprises thermoplastic polyurethane.

Description:
This application claims the benefit of provisional patent application No. 62/167,192, filed May 27, 2015, which is hereby incorporated by reference herein in its entirety. 
    
    
     BACKGROUND 
     This relates generally to items formed from strands of material and, more particularly, to items formed from strands of material such as insulated conductive strands with conductive cores. 
     It may be desirable to form items such a bags, clothing, and other items from intertwined strands of material. For example, woven or knitted fabric or braided strands may be used in forming portions of an item. 
     In some situations, may be desirable for some or all of a strand of material in an item to be conductive. Conductive strands may be used, for example, to carry signals between circuitry in different portions of an item. Strands such as conductive strands may serve both mechanical functions (e.g., by forming a part of a fabric) and/or electrical functions (e.g., by conveying signals). 
     Challenges may arise when forming items such as fabric-based items with conductive strands. It is often desirable for conductive strands to exhibit good mechanical properties, such as high strength and flexibility. Because conductive strands may need to carry electrical signals, the resistance of a conductive strand should generally not be too high. Conductive strands should also be compatible with the non-conductive strands in a fabric and should not form undesired short circuits with surrounding structures. If care is not taken, conductive strands in a fabric-based item may be overly fragile, may exhibit poor signal carrying capabilities, may be insufficiently isolated from surrounding structures, or may adversely affect the appearance and feel of the item. 
     It would therefore be desirable to be able to provide strand-based items that incorporate improved conductive strands. 
     SUMMARY 
     An item may include fabric or other materials formed from intertwined strands of material. The item may include circuitry that produces signals. The strands of material may include non-conductive strands and conductive strands. Strands may be intertwined using weaving equipment, knitting equipment, braiding equipment, or other equipment for intertwining strands of material. If desired, the non-conductive strands and conductive strands may be close in size (e.g., to minimize or eliminate perceptible differences in the appearance and feel of the non-conductive and conductive strands). 
     The conductive strands may carry the signals produced by the circuitry. Each conductive strand may have a strand core, a conductive coating on the strand core, and an insulating coating on the conductive coating. The strand cores may be formed from polymers such as para-aramids and aromatic polyesters (as examples). The conductive coating may be formed from a metal such as silver or other metals. The insulating coating may be a relatively thin insulator such as an insulator with a thickness of less than 5 microns or other suitable thickness. Examples of materials that may be used for forming the insulator include polyvinyl formal, polyester-polyimide, polyamide-polyimide, polyamide, polyimide, polyester, polytetrafluoroethylene, polyurethane, and other polymers. 
     Polymer strand cores may be formed by extrusion, spinning, or other techniques. Metal coatings for the strand cores may be formed by electrochemical deposition or other metal deposition techniques. Insulating layers may be formed by applying liquid polymer in a thin layer to the exterior of a strand that has been coated with metal and by applying heat or otherwise curing the liquid polymer. In some arrangements, insulating layers may be formed from non-conductive strands that are wrapped (e.g., braided or twisted) around conductive cores. 
     Electrical connections may be made between intertwined conductive strands by selectively removing portions of the outer insulating layer to expose the conductive cores of overlapping conductive strands. A conductive material such as solder or conductive epoxy may be applied to the exposed portions of the conductive cores to electrically and mechanically connect the overlapping conductive strands. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic diagram of an illustrative item that may include strands of material in accordance with an embodiment. 
         FIG. 2  is a diagram of a portion of a fabric with conductive strands in accordance with an embodiment. 
         FIG. 3  is a cross-sectional side view of an illustrative conductive strand having a conductive core formed from polymer that is coated with conductive material in accordance with an embodiment. 
         FIG. 4  is a cross-sectional side view of an illustrative conductive strand having a solid conductive core in accordance with an embodiment. 
         FIG. 5  is a diagram of illustrative equipment of the type that may be used in forming insulated conductive strands and strand-based items that include insulated conductive strands in accordance with an embodiment. 
         FIG. 6  is a perspective view of illustrative insulated conductive strands that may be electrically connected in accordance with an embodiment. 
         FIGS. 7A, 7B, and 7C  are cross-sectional side views of illustrative conductive strands showing how the conductive strands may be electrically connected in accordance with an embodiment. 
         FIG. 8  is a top view of illustrative conductive strands that may include bond regions where bond pads are electrically connected to the conductive cores of the conductive strands in accordance with an embodiment. 
         FIG. 9  is a cross-sectional side view of illustrative conductive strands that may include shielding in accordance with an embodiment. 
         FIG. 10  is a cross-sectional side view of an illustrative conductive strand over which a ground plane structure is formed in accordance with an embodiment. 
         FIG. 11  is a flow chart of illustrative steps involved in forming electrical connections with insulated conductive strands in accordance with an embodiment. 
         FIG. 12  is a flow chart of illustrative steps involved in forming conductive structures on insulated conductive strands in accordance with an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Strands of material may be incorporated into strand-based items such as strand-based item  10  of  FIG. 1 . Item  10  may be an electronic device or an accessory for an electronic 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 fabric-based item  10  is mounted in a kiosk, in an automobile, airplane, or other vehicle, other electronic equipment, or equipment that implements the functionality of two or more of these devices. If desired, item  10  may be a removable external case for electronic equipment, may be a strap, may be a wrist band or head band, may be a removable cover for a device, may be a case or bag that has straps or that has other structures to receive and carry electronic equipment and other items, may be a necklace or arm band, may be a wallet, sleeve, pocket, or other structure into which electronic equipment or other items may be inserted, may be part of a chair, sofa, or other seating (e.g., cushions or other seating structures), may be part of an item of clothing or other wearable item (e.g., a hat, belt, wrist band, headband, etc.), or may be any other suitable strand-based item. 
     Strands in strand-based item  10  may form all or part of a housing wall for an electronic device, may form internal structures in an electronic device, or may form other strand-based structures. Strand-based item  10  may be soft (e.g., item  10  may have a fabric surface that yields to a light touch), may have a rigid feel (e.g., the surface of item  10  may be formed from a stiff fabric), may be coarse, may be smooth, may have ribs or other patterned textures, and/or may be formed as part of a device that has portions formed from non-fabric structures of plastic, metal, glass, crystalline materials, ceramics, or other materials. 
     Item  10  may include intertwined strands  12 . The strands may be intertwined using strand intertwining equipment such as weaving equipment, knitting equipment, braiding equipment, or equipment that intertwines strands by entangling the strands with each other in other ways (e.g., to form felt). Intertwined strands  12  may, for example, form woven or knitted fabric or other fabric (i.e., item  10  may be a fabric-based item), a braided cord, etc. 
     Strands  12  may be single-filament strands or may be threads, yarns, or other strands that have been formed by intertwining multiple filaments of material together. Strands  12  may be formed from polymer, metal, glass, graphite, ceramic, natural fibers such as cotton, bamboo, wool, or other organic and/or inorganic materials and combinations of these materials. Strands  12  may be insulating or conductive. 
     Conductive coatings such as metal coatings may be formed on non-conductive strands (e.g., plastic cores) to make them conductive and strands such as these may be coated with insulation or left bare. Reflective coatings such as metal coatings may be applied to strands  12  to make them reflective. Strands  12  may also be formed from single-filament metal wire, multifilament wire, or combinations of different materials. 
     Strands  12  may be conductive along their entire length or may have conductive segments (e.g., metal portions that are exposed by locally removing insulation or that are formed by adding a conductive layer to a portion of a non-conductive strand.). Threads and other multifilament yarns that have been formed from intertwined filaments may contain mixtures of conductive fibers and insulating fibers (e.g., metal strands or metal coated strands with or without exterior insulating layers may be used in combination with solid plastic fibers or natural fibers that are insulating). 
     Item  10  may include additional mechanical structures  14  such as polymer binder to hold strands  12  together, support structures such as frame members, housing structures (e.g., an electronic device housing), and other mechanical structures. 
     Circuitry  16  may be included in item  10 . Circuitry  16  may include components that are coupled to strands  12 , components that are housed within an enclosure formed by strands  12 , components that are attached to strands  12  using welds, solder joints, adhesive bonds (e.g., conductive adhesive bonds), crimped connections, or other electrical and/or mechanical bonds. Circuitry  16  may include metal structures for carrying current, integrated circuits, discrete electrical components such as resistors, capacitors, and inductors, switches, connectors, light-emitting components such as light-emitting diodes, audio components such as microphones and speakers, vibrators, solenoids, piezoelectric devices, and other electromechanical devices, connectors, microelectromechanical systems (MEMs) devices, pressure sensors, light detectors, proximity sensors, force sensors, moisture sensors, temperature sensors, accelerometers, gyroscopes, compasses, magnetic sensors, touch sensors, and other sensors, components that form displays, touch sensors arrays (e.g., arrays of capacitive touch sensor electrodes to form a touch sensor that detects touch events in two dimensions), and other input-output devices. Circuitry  16  may also include control circuitry such as non-volatile and volatile memory, microprocessors, application-specific integrated circuits, system-on-chip devices, baseband processors, wired and wireless communications circuitry, and other integrated circuits. 
     Item  10  may interact with electronic equipment or other additional items  18 . Items  18  may be attached to item  10  or item  10  and item  18  may be separate items that are configured to operate with each other (e.g., when one item is a case and the other is a device that fits within the case, etc.). Circuitry  16  may include antennas and other structures for supporting wireless communications with item  18 . Item  18  may also interact with strand-based item  10  using a wired communications link or other connection that allows information to be exchanged. 
     In some situations, item  18  may be an electronic device such as a cellular telephone, computer, or other portable electronic device and strand-based item  10  may form a case or other structure that receives the electronic device in a pocket, an interior cavity, or other portion of item  10 . In other situations, item  18  may be a wrist-watch device or other electronic device and item  10  may be a strap or other strand-based item that is attached to item  18 . In still other situations, item  10  may be an electronic device, strands  12  may be used in forming the electronic device, and additional items  18  may include accessories or other devices that interact with item  10 . 
     If desired, magnets and other structures in items  10  and/or  18  may allow items  10  and  18  to interact wirelessly. One item may, for example, include a magnet that produces a magnetic field and the other item may include a magnetic switch or magnetic sensor that responds in the presence of the magnetic field. Items  10  and  18  may also interact with themselves or each other using pressure-sensitive switches, pressure sensors, force sensors, proximity sensors, light-based sensors, interlocking electrical connectors, etc. 
     The strands that make up item  10  may be intertwined using any suitable strand intertwining equipment. For example, strands  12  may be woven together to form a fabric. The fabric may have a plain weave, a satin weave, a twill weave, or variations of these weaves, may be a three-dimensional woven fabric, or may be other suitable woven fabric. If desired, the strands that make up item  10  may be intertwined using knitting equipment, braiding equipment, or other strand intertwining equipment. Item  10  may also incorporate more than one type of fabric or intertwined strand-based material (e.g., item  10  may include both woven and knitted portions). 
     The strands that make up item  10  may be intertwined to form a fabric such as illustrative fabric  20  of  FIG. 2 . Fabric  20  may include strands  12 . Strands  12  may be formed from conductive and/or insulating materials. As an example, fabric may be formed from insulating strands  32  interspersed with conductive strands  22 . In the illustrative configuration of  FIG. 2 , a first conductive strand  22  extends vertically and electrically connects node A with junction  24  and a second conductive strand  22  extends horizontally (i.e., perpendicular to the first conductive strand) and electrically connects node B with junction  24 . At the intersection of the first and second conductive strands at junction  24 , the first and second strands may be electrically connected using mechanical contact, solder, welds, conductive adhesive, a crimped metal connection or other metal connector, or other electrical connection structure. Using this type of technique, desired signal paths such as illustrative signal path  26  between nodes A and B may be formed within fabric  20  (e.g., to form signal busses, to form electrodes or other parts of sensors, to form other conductive structures, etc.). 
     Conductive strands such as conductive strands  22  in illustrative fabric  20  for item  10  may be formed from one or more layered materials. For example, conductive strand  22  may have a core (e.g., an elongated member such as a monofilament), a conductive inner coating, and an outer insulating coating. 
     The different portions of the conductive strand may be formed from different materials or, if desired, two or more of the portions of the conductive strand may be formed from the same material. As an example, a conductive strand may have a core and an outer coating that are formed from a common dielectric and that are separated by an intermediate layer formed from a conductive material. Configurations may also be used in which a conductive strand has a core formed from a first dielectric and an outer layer formed from a second dielectric and in which the first and second dielectrics are separated from each other by an intervening conductive layer such as a metal layer. 
     In some configurations, conductive strand  22  may contain polymer. For example, conductive strand  22  may contain a polymer core to provide strand  22  with strength and flexibility. Polymer may also be used in forming insulating outer coating layers. Examples of polymers that may be used in forming a core and/or an outer insulating coating for conductive strand  22  include polyamide (nylon—e.g., nylon6, nylon6,6, nylon 11), aromatic polyamide (i.e., para-aramids such as Kevlar® or other aramids), polyimide, polyester, polyolefin, acrylic, aromatic polyesters such as Vectran®, polyethylene, extruded cellulosic polymers such as rayon and Tencel®, polyvinyl formal, polyester-polyimide, polyamide-polyimide, polytetrafluoroethylene, and polyurethane. Other polymers or mixtures of these polymers may be used, if desired. Inorganic materials may also be used in forming dielectric strand cores and insulating layers. Illustrative configurations in which these strand structures are formed from polymers are sometimes described herein as an example. 
     The polymer materials of strand  22  may be formed from conductive organic material, from insulating polymeric materials (e.g., materials to form a dielectric core and/or outer coating), from polymer that includes conductive filler such as particles of metal, particles of carbon nanotube material, graphene particles, fibrous carbon material, or other conductive particles. Conductive filler may be incorporated into the polymer in a concentration that renders a portion of strand  22  conductive or may be incorporated into the polymer in a lower concentration (e.g., to promote adhesion or otherwise enhance compatibility with other portions of strand  22  without necessarily increasing the conductivity of the polymer to a level that allows the material to serve as a conductive signal path in fabric  20 ). 
     In some situations, monofilaments may be formed of metal or polymer (i.e., polymer with conductive filler or without conductive filler). These monofilaments may be intertwined to form strands  22  or portions of strands  22 . In general, strands  22  may have one or more materials, two or more materials, three or more materials, four or more materials, or five or more materials. The structures of strands  22  may incorporate conductive materials such as metal, insulating materials such as polymer, conductive organic materials such as conductive polymer, polymer filled with metal particles and other conductive filler, other materials, and/or combinations of these materials. 
     A cross-sectional side view of illustrative strand  22  that may be used in fabric  20  is shown in  FIG. 3 . As shown in  FIG. 3 , conductive strand  22  may have core  28 , conductive coating  30 , and insulating coating  34 . Core  28  of  FIG. 3  has a circular cross-sectional shape, but core  28  may have other shapes if desired. Core  28  may be formed from para-aramid fiber (e.g., Kevlar®), spun aromatic polyester fiber (e.g., Vectran®), or other polymer fiber. Core  28  is preferably thermally stable (e.g., core  28  is preferably able to withstand exposure to elevated temperatures without incurring damage). The elevated temperatures may be, for example, temperatures of 200-300° C., more than 150° C., more than 250° C., more than 350° C., less than 250° C., 210-220° C., or other suitable temperatures. Core  28  also preferably has a high elastic modulus (Young&#39;s modulus), such as a modulus of 50-250 GPa, 50-150 GPa, 100-200 GPa, more than 50 GPa, less than 250 GPa, etc. If desired, core  28  may have other advantageous physical attributes such as being insensitive to degradation due to exposure to light, having a good abrasion resistance, being highly flexible, exhibiting a high strength-to-weight ratio, forming a good electrical insulator, etc. 
     To form fabrics and other intertwined strands with desired properties, it may be desirable for the diameter of core  28  to be relatively small. As an example, diameter D of core  28  may be 50-70 microns, 25-100 microns, less than 100 microns, less than 150 microns, more than 10 microns, 10-200 microns, 10-500 microns, 150-250 microns, more than 50 microns, less than 400 microns, or other suitable diameter. The linear mass density of core  28  may be 220 denier, 130 denier, 55 denier, 28 denier, less than 100 denier, less than 75 denier, 75-20 denier, 75-25 denier, less than 60 denier, 60-25 denier, more than 10 denier, more than 20 denier, or other suitable linear mass density. 
     Examples of metals that may be used in forming conductive coating  30  include gold, silver, copper, aluminum, nickel, palladium, molybdenum, platinum, titanium, and tungsten. Other metals may also be used in forming coating  30 . The thickness T 1  of conductive coating  30  may be 25 microns, more than 1 micron, more than 5 microns, less than 25 microns, less than 10 microns, less than 100 microns, 10-50 microns, 20-70 microns, more than 15 microns, more than 20 microns, less than 35 microns, less than 50 microns, less than 5 microns, or other suitable thickness. Coating  30  may be a metal (e.g., an elemental metal such as silver and/or a metal alloy) that has been deposited by electrochemical deposition, physical vapor deposition, etc. or may be any other suitable conductive layer. 
     Insulating coating  34  may have a thickness T 2  of 1-2 microns, more than 0.5 microns, less than 3 microns, less than 4 microns, 0.4-5 microns, less than 5 microns, less than 10 microns, less than 15 microns, less than 20 microns, 0.2-10 microns, more than 0.7 microns, or other suitable thickness. Coating  34  may include one or more dielectric sublayers (e.g., one layer, two layers, three layers, four layers, or more than four layers). To ensure that strand  22  can withstand elevated temperatures, coating  34  is preferably able to withstand elevated temperatures (e.g., temperatures of 200-300° C., more than 150° C., more than 250° C., more than 350° C., less than 250° C., 210-220° C., or other suitable temperatures). Examples of insulating coating materials that may be used for coating  34  include polyvinyl formal, polyester-polyimide, polyamide-polyimide, polyamide, polyimide, polyester, polytetrafluoroethylene, and polyurethane (e.g., thermoplastic polyurethane). Other polymers or mixtures of these polymers may be used, if desired. In configurations in which coating layer  34  is formed from multiple sublayers, each sublayer may be formed from the same material or some or all of the sublayers may be formed from different materials. 
     The example of  FIG. 3  in which conductive strand  22  is formed from a polymer core surrounded by a conductive coating is merely illustrative. If desired, conductive strand  22  may include a solid conductive core as shown in  FIG. 4 . In the example of  FIG. 4 , strand  22  includes a conductive core  28  and an insulating coating  34 . Core  28  of  FIG. 4  may be formed from metal (e.g., steel, gold, silver, copper, aluminum, nickel, palladium, molybdenum, platinum, titanium, tungsten, or other suitable metal). 
     As used herein, “conductive core” may refer to a polymer core coated with conductive material of the type shown in  FIG. 3  or a solid conductive core of the type shown in  FIG. 4 . Arrangements in which conductive strands  22  include a polymer core  28  coated with conductive material  30  are sometimes described herein as an example. 
       FIG. 5  is a diagram showing different types of equipment  60  that may be used in processing strands  12  (e.g., non-conductive strands  28  and conductive strands  22 ) and/or that may be used in processing strand-based item  10 . As shown in  FIG. 5 , equipment  60  may include strand core formation equipment  68 . Equipment  68  may include, for example, equipment for extruding and/or otherwise forming polymer cores for strands  12 . Conductive coating application tool  62  may be used to apply one or more conductive coatings. For example, tool  62  may be used to apply a metal coating such as coating  30  to a polymer strand core such as core  28  to form a conductive strand  22 . Dielectric coating application tool  66  may be used to apply a polymer layer or other insulating coating such as insulating coating  34 . For example, tool  66  may be used to apply a thin polymer coating to the exposed metal coating on a polymer strand core, thereby forming an insulated conductive strand  22 . 
     Equipment  64  may be used in processing strands  12 . Equipment  64  may include a heat source (e.g., a flame, a heated metal structure or other heated structure, a lamp that produces heat, an oven, etc.). Equipment  64  may also include a laser, light-emitting diode, or other light source (e.g., an infrared laser or infrared light-emitting diode, a visible laser or visible light-emitting diode, and/or an ultraviolet laser or light-emitting diode). By applying heat or light or other energy to strands  12  or by using equipment  64  to mechanically or chemically remove material from strands  12 , coatings can be selectively removed, liquid polymers and other coating materials may be cured, the texture of strand  12  may be altered, or other strand modifications can be made. 
     Equipment  64  may be used in attaching electrical components such as electrical components in circuitry  16  of  FIG. 1  to strands such as conductive strands  22 . For example, equipment  64  may be used to attach electrical components to strands  22  using solder joints, crimped metal connections, welds, conductive adhesive, or other conductive attachment structures. The electrical components that are attached to strands in this way may include light-emitting components, integrated circuits, light-emitting diodes, light-emitting diodes that are packaged with transistor-based circuitry such as communications circuitry and/or light-emitting diode driver circuitry that allows each component to operate as a pixel in a display, discrete components such as resistors, capacitors, and inductors, audio components such as microphones and/or speakers, sensors such as touch sensors (with or without co-located touch sensor processing circuitry), accelerometers, temperature sensors, force sensors, microelectromechanical systems (MEMS) devices, transducers, solenoids, electromagnets, pressure sensors, light-sensors, proximity sensors, buttons, switches, two-terminal devices, three-terminal devices, devices with four or more contacts, etc. Electrical connections for attaching electrical components to strands  12  using equipment  64  may be formed using solder, conductive adhesive, welds, molded package parts, mechanical fasteners, wrapped strand connections, press-fit connections, crimped connections (e.g., bend metal prong connections), and other mechanical connections, portions of liquid coatings (e.g., metallic paint, conductive adhesive, etc.) that are selectively applied to strands  12  using equipment  64 , or using any other suitable arrangement for forming an electrical short between conductive structures. 
     Strand intertwining equipment  70  (e.g., weaving equipment, knitting equipment, braiding equipment, or other strand intertwining equipment) may be used in intertwining strands  12  to form fabric and other structures for strand-based item  10 . Equipment  60  may be used to process strands  12  before, during, or after processing of strands  12  with equipment  70  to form item  10 . 
     To form electrical connections with conductive strands  22 , it may be desirable to selectively remove portions of outer insulating layer  34  to expose conductive coating  30 .  FIG. 6  is a perspective view of intertwined strands  22 A and  22 B showing an illustrative region  40  where an electrical connection may be formed with one or both of strands  22 A and  22 B. In some arrangements, it may be desirable to electrically connect the conductive cores of strand  22 A and strand  22 B at region  40 . In other arrangements, it may be desirable to electrically connect a component or bond pad to one or both of strands  22 A and  22 B in region  40 . 
     To electrically connect the conductive material  30  of strand  22 A with the conductive material  30  of strand  22 B, outer insulating coating  34  may be removed from strand  22 A and  22 B in region  40 . A conductive material such as solder, conductive epoxy, conductive ink, or other suitable conductive material may be used to electrically connect exposed conductive layer  30  of strand  22 A to the exposed conductive layer  30  of strand  22 B. 
       FIGS. 7A, 7B, and 7C  show illustrative steps involved in electrically and mechanically connecting conductive layer  30  of strand  22 A with conductive layer  30  of strand  22 B. As shown in  FIG. 7A , strands  22 A and  22 B each have a conductive core formed from core  28  coated with conductive material  30 . The conductive cores of strands  22 A and  22 B are insulated with dielectric coating  34 . At this stage, dielectric coating  34  in region  40  separates conductive layer  30  of strand  22 A from conductive layer  30  of strand  22 B in region  40 . 
     To electrically connect conductive layer  30  of strand  22 A and conductive layer  30  of strand  22 B, dielectric coating  34  on strands  22 A and  22 B in region  40  may be selectively removed to expose metal  30  in region  40 . If desired, equipment such as equipment  64  of  FIG. 5  may be used to selectively remove dielectric coating  34  in region  40 . Dielectric coating may be removed by applying heat (e.g., from a flame, a heated metal structure or other heated structure, a lamp that produces heat, an oven, etc.), light (e.g., from an infrared laser or infrared light-emitting diode, a visible laser or visible light-emitting diode, and/or an ultraviolet laser or light-emitting diode), or chemicals (e.g., to chemically remove material  34  from strands  22 A and  22 B). By applying heat or light or other energy to strands  22  or by using equipment  64  to mechanically or chemically remove material from strands  22 , coating  34  can be selectively removed from strands  22  in regions where access to the conductive core of strands  22  is desired. 
     As shown in  FIG. 7B , conductive material  36  may be formed on exposed metal  30  of strands  22 A and  22 B in region  40  to thereby electrically connect metal layer  30  of strand  22 A with metal layer  30  of strand  22 B. Material  36  may be solder, conductive epoxy, conductive ink, or other suitable conductive material. 
     If desired, other methods of electrically connecting exposed metal  30  of strand  22 A with exposed metal  30  of strand  22 B may be used. For example, electrical and mechanical connections in regions such as region  40  may be formed using solder, conductive adhesive, welds, molded package parts, mechanical fasteners, wrapped strand connections, press-fit connections, crimped connections (e.g., bend metal prong connections), and other mechanical connections, portions of liquid coatings (e.g., metallic paint, conductive adhesive, etc.) that are selectively applied to strands  12  using equipment  64 , or using any other suitable arrangement for forming an electrical short between metal  30  of strand  22 A and metal  30  of strand  22 B. 
     If desired, equipment  64  of  FIG. 5  may be used in forming electrical connection structure  36 . Equipment  64  may, for example, include a pick-and-place tool for depositing solder or other conductive materials in region  40 . 
     In some arrangements, electrical connection structure  36  may be formed without removing dielectric coating  34 . For example, a low-viscosity conductive material (e.g., a conductive ink or other conductive material with low viscosity) may be deposited on dielectric layer  34  in region  40  and may seep into dielectric layer  34  to form conductive structure  36 . In this way, an electrical connection may be formed between metal  30  of strand  22 A and metal  30  of strand  22 B using a conductive portion  36  of dielectric coating  34 . 
     If desired, region  40  of strands  22 A and  22 B may be sealed or encapsulated to protect the electrical connection and prevent contaminants or abrasive materials from compromising the connection between metal  30  of strand  22 A and metal  30  of strand  22 B. As shown in  FIG. 7C , for example, encapsulation layer  38  may be formed over conductive structure  36  to form a seal around the electrical connection between strands  22 A and  22 B. Examples of materials that may be used in forming encapsulation layer  38  include epoxy, silicone, urethane, polyurethane (e.g., thermoplastic polyurethane), acrylic, polyester, other polymers, or other suitable materials. The use of sealant, encapsulation, or potting material in regions  40  may increase the robustness of the electrical and mechanical connection at junction  40  and may provide a watertight seal that prevents moisture and other contaminants from seeping into or between strands  22  in region  40 . Metal  30  of strand  22 A and core  28  of strand  22 A may extend continuously through region  40 . Encapsulation layer  38  may cover strands  22 A and  22 B in region  40 . Insulating coating  34  of strand  22 A and insulating coating  34  of strand  22 B may extend outside region  40 . 
     In addition to forming electrical shorts between conductive cores of intertwined strands  22 , it may be desirable to expose conductive cores of strands  22  in order to form electrical connections between an electronic component and a conductive strand  22 . In order to mount electronic components to conductive strands  22 , equipment  64  may be used to electrically connect bond pads to the conductive cores of strands  22 .  FIG. 8  is a top view of intertwined conductive strands  22  showing how bond pads  42  may be formed on conductive strands  22 . 
     Bond pads  42  may be formed by selectively removing portions of outer insulating layer  34  in regions  40 , applying conductive material  36  such as solder to the exposed portions of metal layer  30  in regions  40 , and forming bond pads  42  on conductive material  36 . If desired, conductive material  36  may be used to form bond pads  42  or bond pads  42  may be formed separately from material  36 . 
     In other arrangements, bond pads  42  may be formed without removing dielectric layer  34 . For example, a low-viscosity conductive material (e.g., a conductive ink or other conductive material with low viscosity) may be deposited on dielectric layer  34  in regions  40  and may seep into dielectric layer  34  to form bond pads  42  or to form a conductive structure on which bond pads  42  are formed. In this way, bond pads  42  may be electrically connected to the conductive core of strands  22  using a conductive portion of dielectric layer  34 . 
     In some scenarios, it may be desirable to apply conductive materials to strands  22  without shorting the conductive materials to the conductive cores of strands  22 . As shown in  FIG. 9 , for example, it may be desirable to provide strands  22  with shielding layers such as shielding layer  44 . Shielding layer  44  may be formed from layer of conductive material such as metal or conductive polymer that surrounds or partially surrounds strand  22  in region  50 . Shielding layer  44  may be separated from interior metal layer  30  by insulating layer  34 . Shielding layer  44  may be kept at a ground potential while metal layer  30  is used to convey electrical signals. If desired, shielding layer  44  and metal layer  30  may form a coaxial structure in which outer conductor  44  and inner conductor  30  share a common longitudinal axis. 
       FIG. 10  is a top view of another suitable arrangement in which conductive structure  44  extends over a portion  50  of conductive strand  22 . Conductive structure  44  may be used for shielding and/or may form a ground plane (e.g., for an antenna or other electronic component). 
       FIG. 11  is a flow chart of illustrative steps involved in forming electrical connections with insulated conductive strands  22 . 
     At step  200 , dielectric layer application equipment  66  may be used to form dielectric outer coating  34  on layer  30 , thereby forming conductive strand  22 . If desired, multiple strands may be braided together (e.g., 5-10 strands, more than 3 strands, fewer than 12 strands, etc.) to form a thread or other strand that contains multiple smaller strands. These smaller strands may be insulating and/or conductive strands. Insulating layer  34  may be formed by applying a liquid polymer coating with a relatively thin thickness and curing the applied coating using heat or light to produce cured coating  34  (e.g., a coating having a thickness of less than 5 microns or other suitable thickness). In other arrangements, insulating layer  34  may be formed by extruding non-conductive material around a conductive core, dipping a conductive core in a non-conductive material, or wrapping a conductive core in non-conductive strands (e.g., such that the conductive core is surrounded by twisted or braided non-conductive strands). 
     At step  202 , intertwining equipment  70  may be used to intertwine strands  12  to form a strand-based material. The strands that are intertwined in step  202  may include conductive strands, non-conductive strands, insulated conductive strands, and/or conductive strands without insulation. 
     At step  204 , equipment  64  of  FIG. 5  may be used to remove insulating layer  34  in regions where an electrical connection is to be made. For example, insulating layer  34  may be removed from regions  40  where an electrical connection is to be made between the conductive cores of overlapping conductive strands (e.g., as shown in  FIGS. 7A, 7B, and 7C ), or insulating layer  34  may be removed from regions  40  where an electrical connection is to be made between an electronic component and a conductive strand (e.g., as shown in  FIG. 8 ). Equipment  64  may include a heat source (e.g., a flame, a heated metal structure or other heated structure, a lamp that produces heat, an oven, etc.). Equipment  64  may also include a laser, light-emitting diode, or other light source (e.g., an infrared laser or infrared light-emitting diode, a visible laser or visible light-emitting diode, and/or an ultraviolet laser or light-emitting diode). By applying heat or light or other energy to strands  22  to mechanically or chemically remove insulating material  34  from strands  22 , conductive layer  30  in strands  22  can be selectively exposed in regions  40  where an electrical connection is to be made. 
     At step  206 , conductive material such as conductive material  36  may be applied to the exposed conductive portions of strands  22 . Material  36  may be solder, conductive epoxy, conductive ink, or other suitable conductive material. If desired, other methods of forming electrical connections with the exposed metal of strands  22  may be used. For example, electrical and mechanical connections in regions of exposed conductor may be formed using solder, conductive adhesive, welds, molded package parts, mechanical fasteners, wrapped strand connections, press-fit connections, crimped connections (e.g., bend metal prong connections), and other mechanical connections, portions of liquid coatings (e.g., metallic paint, conductive adhesive, etc.) that are selectively applied to strands  22  using equipment  64 , or any other suitable arrangement for forming an electrical connection with exposed conductor on strands  22 . The conductive material applied in step  206  may electrically connect the conductive cores of two overlapping strands and/or may be used to form a bond pad on the exposed conductor of strand  22 . 
     At optional step  208 , bond locations  40  may be sealed or encapsulated to protect the electrical connection and prevent contaminants or abrasive materials from compromising the connection to exposed conductor  30  or conductive structure  36 . The encapsulation layer may, for example, be formed over conductive structure  36  to form a seal around the electrical connection between two overlapping strands  22  (e.g., as shown in  FIG. 7C ). Examples of materials that may be used in forming encapsulation layer  38  include epoxy, silicone, urethane, polyurethane (e.g., thermoplastic polyurethane), acrylic, polyester, other polymers, or other suitable materials. 
     The example of  FIG. 11  in which insulating layer  34  is removed prior to applying conductive material  36  is merely illustrative.  FIG. 12  is a flow chart of illustrative steps involved in forming conductive structures on strands  22  by applying conductive material  36  prior to or without removing insulating layer  34 . 
     At step  300 , dielectric layer application equipment  66  may be used to form dielectric outer coating  34  on layer  30 , thereby forming conductive strand  22 . If desired, multiple strands may be braided together (e.g., 5-10 strands, more than 3 strands, fewer than 12 strands, etc.) to form a thread or other strand that contains multiple smaller strands. These smaller strands may be insulating and/or conductive strands. Insulating layer  34  may be formed by applying a liquid polymer coating with a relatively thin thickness and curing the applied coating using heat or light to produce cured coating  34  (e.g., a coating having a thickness of less than 5 microns or other suitable thickness). In other arrangements, insulating layer  34  may be formed by extruding non-conductive material around a conductive core, dipping a conductive core in a non-conductive material, or wrapping a conductive core in non-conductive strands (e.g., such that the conductive core is surrounded by twisted or braided non-conductive strands). 
     At step  302 , intertwining equipment  70  may be used to intertwine strands  12  to form a strand-based material. The strands that are intertwined in step  202  may include conductive strands, non-conductive strands, insulated conductive strands, and/or conductive strands without insulation. 
     At step  304 , conductive material such as conductive material  36  may be applied to the desired portions of strands  22 . For example, conductive material  36  may be applied to regions  40  where an electrical connection is to be made between the conductive cores of overlapping conductive strands (e.g., as shown in  FIGS. 7A, 7B, and 7C ), conductive material  36  may be applied to regions  40  where an electrical connection is to be made between an electronic component and a conductive strand (e.g., as shown in  FIG. 8 ), or conductive material  36  may be applied to regions where shielding or grounding is desired (e.g., regions  50  of  FIGS. 9 and 10 ). This may include, for example, using a pick-and-place tool to deposit solder that heats and thereby removes layer  34 . In other arrangements, conductive material  36  may be a low-viscosity conductive ink that seeps into or mixes with dielectric layer  34  to form a conductive portion in dielectric layer  34 . If shielding or grounding is desired, conductive structure  44  ( FIGS. 9 and 10 ) may be formed over dielectric layer  34  such that dielectric layer  34  separates conductor  30  from conductor  44 . With this type of arrangement, conductive material  44  may be formed from a material that does not penetrate or remove dielectric layer  34  (e.g., a viscous conductive ink, a metal coating, or other suitable conductive material). 
     At optional step  306 , locations where conductive material  36  has been applied may be sealed or encapsulated to protect the conductive material from contaminants and prevent abrasive materials from comprising the connection to exposed conductor  30  or conductive structure  36 . The encapsulation layer may, for example, be formed over conductive structure  36  to form a seal around the electrical connection between two overlapping strands  22  (e.g., as shown in  FIG. 7C ). Examples of materials that may be used in forming encapsulation layer  38  include epoxy, silicone, urethane, polyurethane (e.g., thermoplastic polyurethane), acrylic, polyester, other polymers, or other suitable materials. 
     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: 20160504
Publication Date: 20201124
Grant Date: 20201124
Priority Date: 20150527
Inventors: SUNSHINE, Daniel D.
PODHAJNY, DANIEL A.
KINDLON, DAVID M.
CREWS, KATHRYN P.
WALKER, JOSEPH B.
Assignee: APPLE INC
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Family ID: 73462219