Apparatus for making electrical connections to flexible circuits

Abstract

An apparatus for making an electrical connection to electrical circuits on stretchable, flexible substrates include a support region and a connection region that are foldably connected. The regions further including connection pads defining sites for attaching a conductive trace. The folding of the regions forms an electrical contact between the connection pads and the circuitry of a stretchable, flexible substrate placed between the regions.

Description

APPARATUS FOR MAKING ELECTRICAL CONNECTIONS TO FLEXIBLE CIRCUITS

[0001] The present disclosure relates generally to the field of printed circuits, substrates, and stretchable electronic components.BACKGROUND

[0002] There are various types of printed circuits for electronic systems which can provide effective performance in normal and extreme use conditions. However, it is difficult to use currently available electrical circuits for reliably electronically coupling to electronics provided on stretchable or flexible substrate materials.BRIEF DESCRIPTION OF THE DRAWINGS

[0003] FIG. 1 is a perspective view of one implementation of an apparatus for making an electrical connection to a circuit disposed on a flexible, stretchable substrate.

[0004] FIG. 2 is a perspective view of a second implementation of an apparatus for making an electrical connection to a circuit disposed on a flexible, stretchable substrate.

[0005] FIG. 3 is a perspective view showing an electrical connection to an implementation of the apparatus of FIGS. 1 and 2.

[0006] FIG. 4 is a view of an implementation of a bendable member and its successive bends to form a ferrule.

[0007] FIG. 5 is a perspective view of the apparatus of FIG. 1 in an initial, unfolded state.

[0008] FIG. 6A is a perspective view of the apparatus of FIG. 1 depicting an intermediate state with external conductive elements attached.

[0009] FIG. 6B is a reverse perspective view of the intermediate state with external conductive elements attached.

[0010] FIG.7 is a perspective view of the apparatus of FIG. 1 in a final, closed state.

[0011] FIG 8. is a top view of the apparatus of FIG. 1 in a fully assembled state.

[0012] FIG. 9A is a perspective view of another implementation of an apparatus for making an electrical connection to a circuit disposed on a flexible, stretchable circuit.

[0013] FIG. 9B is an exploded view of the apparatus of FIG. 9A.

[0014] FIG. 10 is an exploded view showing the alignment between a circuit element and the implementation of the apparatus of FIG. 9A.

[0015] FIG. 11 is a graph showing the measured electrical resistance of a stretchable circuit as a function of the number of stretch cycles.

[0016] FIG. 12 is a graph showing the measured electrical resistance of a stretchable circuit as a function of the number of stretch cycles.

[0017] FIG. 13 is a graph showing the measured electrical resistance of a stretchable circuit as a function of the number of stretch cycles.

[0018] FIG. 14 is a graph showing the measured electrical resistance of a stretchable circuit as a function of the number of wash cycles.

[0019] FIG. 15 is a graph showing the power output of the stretchable circuit as a function of the number of wash cycles.

[0020] FIG. 16 are infrared images of the stretchable circuit before washing and after the 15thwash.DETAILED DESCRIPTION

[0021] Before turning to the FIGURES, it should be understood that the present disclosure is not limited to the details set forth in the description or illustrated in the figures. It should be understood that the terminology used herein is for the purpose of description only and should not be regarded as limiting.

[0022] References herein to positions of elements (e.g., "top", "bottom") are merely used to describe the orientation of various elements in the FIGURES. It should be noted that theorientation of various elements may differ according to other exemplary implementations, and that such variations are intended to be encompassed by the present disclosure.

[0023] Referring now to FIG. 1 , and in brief overview, an implementation of an apparatus 100 for making an electrical connection to a circuit disposed on a flexible, stretchable substrate is shown that includes a support region 102 and a connection region 106. The connection region includes connection pads 110, adhesive windows 112, slots 108, a first opening 114, a second opening 118, a channel 116, and a gas permeable material 120. The support region 102 includes adhesive windows 112 and an extending edge 104.

[0024] Still referring to FIG. 1, and in greater detail, the support region 102 and connection region 106 may be circular in shape. The support region 102 may have a larger diameter than connection region 106 such that the extending edge 104 of support region 102 extends beyond the outer perimeter of the connection region 106. In some implementations, the support region 102 has a thickness of 0.002 inches. In some implementations, the support region 102 may have a thickness of 0.001 inches, 0.004 inches, or 0.005 inches. In some implementations, the support region 102 and connection region 106 may be made of materials such as thermoplastic polyurethane (TPU), thermoplastic polyamide, thermoplastic copolyester, or polyethylene terephthalate (PET). In certain implementations, the support region 102 made of PET provides enhanced thermal stability and provides a coating to maximize the peel-ability of a circuit printed on a flexible, stretchable substrate. In certain implementations, the connection region 106 made of TPU may provide good elasticity for the flexible, stretchable substrate. Although shown in FIG. 1 as circular, the support region 102 and connection region 106 may be different shapes such as a circle, a rectangle, a triangle, a rectangle with rounded corners, a triangle with rounded corners, or an irregular shape. In still other implementations, support region 102 and connection region 106 may have shapes different from one another. In these implementations, support region 102 has an overall largersurface area than the connection region 106 to define an extending edge 104. In some implementations, the support region 102 and connection region 106 may be sized and shaped to define the extending edge 104 only on certain edges of the support region 102. In some implementations, for aesthetic purposes, a textile material or fabric can be used to cover some or all portions of the outer portions of the support region 102, the connection region 110, and / or the flexible, stretchable substrate.

[0025] Still referring to FIG. 1, the extending edge 104 of the support region 102 may be lined with adhesive. The adhesive on the extending edge 104 may be shaped such that it follows the edge profile of the support region 102 and the edge profile of the connection region 106. In some implementations, the adhesive may partially cover the extending edge 104. In some implementations, the adhesive may be disposed non-continuously on the extending edge 104. In some implementations, the adhesive may be disposed on the extending edge 104 in a patterned manner such as a plurality of evenly spaced circular shaped adhesive material, evenly spaced rectangular shaped adhesive material, or irregularly spaced adhesive material. In still other implementations, the adhesive may be applied over the entirety of the support region 102. In some implementations, the adhesive on the extending edge 104 may be 0.002” thick layer. In certain others, the adhesive on the extending edge 104 may be 0.001”, 0.004”, or 0.005” thick layer.

[0026] The connection region 106 may define a plurality of adhesive windows 112 of various coverage areas. As shown in FIG. 1, the adhesive windows 112 on the connection region 106 may be positioned radially around the connection pads 110. In addition, a circular-shaped adhesive window 112 may be defined between the connection pads 110. In some implementations, the adhesive windows 112, may have different shapes such as circle, rectangle, rectangle with rounded corners, triangle, triangle with rounded corners, or irregular shapes. In some implementations, there may be a singular adhesive window 112 surroundingthe outer perimeter of the connection pads 110. In some implementations, there may an adhesive window covering a portion of the area between the connection pads 110.

[0027] In other implementations, the support region 102 may also define a plurality of adhesive windows 112 of various coverage areas. The adhesive windows 112 defined by the support region 102 may be substantially aligned with those defined by the connection region 106. In some implementations, the adhesive windows may have different shapes such as circle, rectangle, rectangle with rounded corners, triangle, triangle with rounded corners, or irregular shapes.

[0028] In some implementations, the adhesive may be a phase change adhesive such as a hot melt adhesive that can adhere to the support region 102, the connection region 106, and the stretchable, flexible substrate (not shown). In some implementations, the adhesive may be an adhesive that flows on the support region 102 and connection region 106 with an application of heat. The adhesive then subsequently cools and solidifies to form a bonded stack of elements including the support region 102, the connection region 106, and the stretchable, flexible substrate placed therebetween. Subsequently, this bonding permits a coupling or an intimate contact between the support region 102, the connection region 106, the connection pads 110, the stretchable, flexible substrate, and the terminals of the stretchable, flexible substrate (not shown). As a result of this coupling or intimate contact, the connection pads 110 and the terminals of the electronics on the stretchable, flexible substrate may move with respect to each other with minimal restriction. This intimate contact can maintain electrical communication between the connection pads 110, a conductive trace, such as a wire, and the electronics on the stretchable, flexible substrate. In addition, in some implementations, the adhesive may be tolerant of multiple wash cycles and mechanical manipulation (e.g., stretching) of the stretchable, flexible substrate. In some implementations, the adhesive can bond well to a variety of materials, such as polyester, polycotton, Lycra, polycarbonate,polyvinyl chloride, polyurethane, acrylonitrile butadiene styrene, wood, leather, fiberglass, aluminum, copper, and steel. In some implementations, the adhesive disposed on the adhesive windows 112 may have a thickness of 0.001”, 0.002”, 0.004”, or 0.005”.

[0029] In some implementations, the connection pads 110 may be a conductive material, such as copper, gold, silver, or platinum. In some implementations, the connection pads 110 may be manufactured using any one of a number of inks manufactured by made by Applied Cavitation, Inc of Goleta, California. Although two connection pads 110 are shown in FIG. 1, any number of connection pads 110 may be used to connect with the flexible, stretchable substrate. In some implementations, the connection pads 110 may have a thickness of 34 mils (34 / 1000 inches). In some implementations, the connection pads 110 may a thickness of 25 mils, 45 mils, or 50 mils. In some implementations, the connection pads 110 may have thickness approximately the diameter of a human hair. In some implementations, the connection pads 110 in electrical contact with the terminals of the stretchable, flexible substrate (not shown) may have a surface area sufficient to conduct an electrical current equal to or greater than 1 amp. In some implementations, the connection pads 110 in electrical contact with the terminals of the stretchable, flexible substrate (not shown) may have a surface area sufficient to conduct an electrical current of 2.5 amps, 4.0 amps, or 5.0 amps. In some implementations, the connection pads 110 may be irregularly shaped. In some implementations, the connection pads 110 may be disposed on the support region 102 and the connection region 106, such that there are connections pads 110 on opposite sides of the stretchable, flexible substrate placed therebetween. In some implementations, a strain relief may be incorporated in the area where the terminals of the flexible, stretchable substrate, the connection pads 110, and / or the adhesive material are bonded with the flexible, stretchable substrate. In some implementations, the connection pads 110 may be spaced apart by a dielectric material.

[0030] In some implementations, the dielectric material may be formed of any material with a relatively large dielectric constant. In certain implementations, the dielectric material may include parylene, fluoropolymer, atomic layer deposition, molecular vapor deposition, and the like materials. In some implementations, the dielectric material can be a polyimide material, for example, a Kapton film, such as those supplied by DuPont of Wilmington, U.S.A. In some implementations, the thickness of the dielectric layer can be 25 mils. In certain implementations, the dielectric material may be 18 mils, 27 mils, or 30 mils.

[0031] Still referring to FIG. 1, the connection pads 110 may define a plurality of slots 108 for receiving a ferrule. In some implementations, the slots 108 may be an assortment of different shapes such as a circle, a rectangle, a triangle, or an irregular shape. In some implementations, the size of the slots 108 may be congruent with the cross-sectional end of a bendable member 402a that forms a ferrule 306. In some implementations, the spacing between a pair of slots 108 may depend on the diameter of a wire 302 placed between the slots 108. In some implementations, the slots 108 may be oriented perpendicular to each other. In yet other implementations, the slots may be arranged at various angles to each other. In some implementations, the slots may be positioned anywhere within the area covered by the connection pads 110.

[0032] Still referring to FIG. 1, the first opening 114 in fluid communication with the channel 116 may be a circular shaped through hole for equalizing the atmospheric pressure that is outside of the flexible, stretchable substrate (not shown) and the pressure within the area of the electrical contact between the terminals of the flexible, stretchable substrate electronics (not shown) and the connection pads 110. In some implementations, the first opening may be a rectangle. In some implementations, the first opening may be a circle, a triangle, a rectangle with rounded corners, or an irregular shape.

[0033] In some implementations, the channel 116 may be a depression formed on the connection region 106. In some implementations, the channel may be formed by the peripheral sides of parallel adhesive material strips. In some implementations, the channel may follow a zig-zag or wavy path which may be implemented to reduce access of water or moisture to the area where the connection pads 110 make electrical contact with the terminals of the flexible, stretchable substrate (not shown).

[0034] Still referring to FIG. 1, the second opening 118 in fluid communication with the channel 116 as shown in FIG. 1. In some implementations, the second opening 118 may be a circle as show in FIG. 1. In some implementations, the second opening 118 may be another shape such as a triangle, a rectangle, a rectangle with rounded corners, or an irregular shape.

[0035] In some implementations, the second opening 118 may be covered by a gas- permeable material 120, as shown in FIG. 1, to reduce access of water or moisture while allowing air and other gases to permeate through the gas-permeable material 120. The gas- permeable material 120 may be affixed to the connection region 106 with adhesive material. In some implementations, the area between the connection pads 110 may be at least partially covered by the gas-permeable material. In other implementations, the area between the connection pads 110 may be completely covered by the gas-permeable material. In some implementations, the gas-permeable material may be 50% Gore-Tex, manufactured by W. L. Associates, Inc. of Newark, U.S.A. In some implementations, the gas-permeable material may be a water-resistant treated polyethene-based material, a water-resistant treated expanded polytetrafluorethylene-based material, nylon, or polyester. Although FIG. 1 depicts an implementation in which connection pads 110 are separated by the first opening 114, the second opening 118, and the channel 116, other positions for the first opening 114, the second opening 118, and the channel 116 are possible.

[0036] Referring now to FIG. 2, and in brief overview, another implementation of the apparatus 100 for making an electrical connection to a circuit disposed on a flexible, stretchable substrate is shown including a protruding edge 202 on the support region 102 in addition to other features defined and described for the implementation of the apparatus 100 such as, the connection region 106, the connection pads 110, the adhesive windows 112, the slots 108, the first opening 114, the second opening 118, the channel 116, and the gas- permeable material 120. The support region 102 includes adhesive windows 112 and the extending edge 104. The adhesive windows 112 and the extending edge 104 provide a defined area for adhesive application on the support region 102 and connection region 106.

[0037] Still referring to FIG. 2, and in greater detail, the protruding edge 202 can provide stability and additional support for the wires 302. Although shown in FIG. 2 as a rectangular shape, the protruding edge 202 may be different shapes including a semicircle, a triangle, a triangle with rounded corners, or an irregular shape. In some implementations, the protruding edge 202 may be sized and shaped so that it only extends on certain edges of the support region 102. In some implementations, the protruding edge 202 may serve as a grabbable edge.

[0038] Referring now to FIG. 3, and in brief overview, an electrical connection between the connection pads 110 and a conductive trace, such as a wire 302, is shown. As shown in FIG. 3, the wires 302 are wrapped in cloth 304 and are attached to the connection region 106.

[0039] Still referring to FIG. 3, and in greater detail, implementation of the apparatus 100 the wires 302 can be securely attached with ferrules 306 that penetrate through the slots 108 on the connection region 106. The ferrules 306 wrap around the wires 302 to create an electrical contact between the wires 302 and the connection pads 110. In some implementations, a textile material or a fabric can be used to cover some or all portions of the support region 102, the connection region 110, and / or the wires 302. In some implementations, the tips ofthe wires 302 may be tinned. In some implementations, the wires 302 may be made of copper, aluminum, gold, silver, or any conductive metal. In some implementations, the wires 302 may be covered with wire insulation or protective coatings such as a nylon jacket, polyvinyl chloride jacket, heat shrink tubing, or wire sheathing. In some implementations, the wires 302 may be solid wire cable. In some implementations, the wires 302 may be 18-gauge, 20-gauge, or 22-gauge.

[0040] In certain implementations, the ferrules 306 may be made of copper, aluminum, or any other type of conductive material. In some implementations, the ferrules 306 may be wire ferrules with circular or rectangular cross-sectional areas. The length of the ferrules 306 can be varied to affix wires of different diameters to the connection region 306. In some implementations, thick ferrules may be used to provide greater stability to the wires 302. In some implementations, a plurality of ferrules of different lengths, thicknesses, and / or materials, may be used in combination.

[0041] Referring now to FIG. 4, and in brief overview, one implementation of a bendable member 402a along with its successive bends 402b-c to form a ferrule 306 are shown. In some implementations, one end of the bendable member 402a is guided through the slots 108 and said end is bent towards the center of the bendable member 402a to form an intermediate state 402b of the ferrule 306. In following, the wire 302 is placed between the slots 108 and the other end of the bent member 402b is guided through the slots 108 and said end is bent towards the center of the bendable member 402b to form another intermediate state 402c of the ferrule 306. Having the wires 302 in place, the bent ends of 402c are further compressed to securely attach the wires 302 to the connection region 106. In other implementations, the intermediate state 402c may be formed prior to placing the wires 302, such that the ends of the intermediate state 402c partially penetrate through the slots 108 allowing insertion of the wires 302 beneath the partially inserted intermediate state 402c of the ferrule 306. In theseimplementations, the wires 302 are securely attached to the connection region 106 following a final compression of the bent ends of 402c. In yet other implementations, both ends of the bendable member 402a may be bent in parallel to form the intermediate state 402c of the ferrule 306. In some implementations, the bending of the bendable member 402a, the insertion of the wire 302, and the insertion of the ends of the bendable member through the slots 108 may be done simultaneously. In some implementations, the process of bending a bendable member 402a may be done manually by hand or with a tool or may be automated with machinery.

[0042] Referring now to FIG. 5, and in brief overview, an isometric view of an unfolded configuration 500 of the implementation of the apparatus 100 is shown including features defined and described for the implementation of the apparatus 100 such as, the support region 102, the connection region 106, connection pads 110, adhesive windows 112, extending edge 104, slots 108, a first opening 114, a second opening 118, a channel 116, and a gas- permeable material 120. As shown in FIG. 5, the support region 102 and connection region 106 are foldably connected. The foldable connection between the support region 102 and the connection region 106 can provide an edge for aligning the terminals of the flexible, stretchable substrate (not shown) when the substrate is positioned between the support region 102 and the connection region 106.

[0043] Still referring to FIG. 5, and in greater detail, the support region 102 may define a plurality of adhesive windows 112 of various coverage areas as shown by the phantom lines in FIG. 5. The adhesive windows 112 defined by the support region 102 may be substantially aligned with those defined by the connection region 106. As shown in FIG. 5, the adhesive windows 112 on the support region 102 may be positioned radially from the center of the support region 102. In addition, a circular-shaped adhesive window 112 may be placed on the center of the support region 102. In some implementations, the adhesive windows 112, mayhave different shapes such as circle, rectangle, rectangle with rounded corners, triangle, triangle with rounded corners, or irregular shapes. In some implementations, there may be a singular adhesive window 112 partially covering or completely covering the area of the support region 102.

[0044] Referring now to FIGS. 6A-6B, and in brief overview, various views of an unfolded configuration 600, 650 of the apparatus 100 including the wires 302 attached with the ferrules 306 to the connection region 106. The view 600 shows the exterior of the connection region 106 which includes the ferrules 306 wrapped around the wires 302 and the ferrules 306 penetrating through the slots 108. For clarity, the view 650 depicts the interior of the apparatus 100 and further shows the electrical contact made between the bent tips of the ferrules 306, and the connection pads 110.

[0045] Referring now to FIG. 7, and in brief overview, a view of a closed configuration 700 of the implementation of the apparatus 100 including the wires 302, the ferrules 306, and illustrative arrows to indicate where heat can be applied on the bottom and the top of the closed configuration to bond with a stretchable, flexible substrate (not shown) placed between the connection region 106 and support region 102 are shown. The application of heat can melt the solid layers of the adhesive material disposed on the connection region 106 and the support region 102. The melting of the solid layers of the adhesive material can cause the adhesive to flow from the connection region 106 and the support region 102 onto the substrate placed between the connection region 106 and the support region 102. The action of mechanically pressing the connection region 106, the support region 102, and the substrate position between can facilitate both spreading of the adhesive and a greater contact or coupling of the connection region 106, the connection pads 110, the affixed ferrules 306, the support region 10 to the stretchable, flexible stretchable substrate. In effect, this can enable a durable electrical communication with a conductive trace, such as the wires 302, when theconnection pads 110 are brought into electrical contact with the terminals of the flexible, stretchable substrate.

[0046] Referring now to FIG. 8, and in brief overview, a wire-assembled configuration 800 of the implementation of the apparatus 100 for making an electrical connection to a circuit disposed on a flexible, stretchable substrate is shown with a plurality of protruding edges 202, 802, where the protruding edge 202 is a rectangular shape and the protruding edge 802 is a semicircular shape.

[0047] Still referring to FIG. 8, and in greater detail, the protruding edge 202 can provide stability and additional support for the wires 302. In some implementations, the protruding edge 802 may serve as a grabbable edge. Although shown in FIG. 8 as certain shapes, the protruding edge 202, 802 may be different shapes including a semicircle, a triangle, a triangle with rounded corners, or an irregular shape. In some implementations, the protruding edge 202, 802 may be sized and shaped so that it only extends on certain edges of the support region 102.

[0048] Referring now to FIG. 9A, and in brief overview, another implementation of an apparatus 900 for making an electrical connection to a circuit disposed on a flexible, stretchable substrate is shown. As shown in FIG. 9A, another implementation of an apparatus 900 includes a dielectric material 902, a plug housing 906, a plug body 908, an adhesive layer 910, a plug cap 912, the connections pads 110, and connection pad terminals 914. Although the implementation of an apparatus 900 is generally rectangular in shape, the apparatus may have other shapes including circular, polygonal, or irregular in shape.

[0049] For clarity, FIG. 9B shows an exploded assembly view of the implementation of an apparatus 900 including the dielectric 902, the connections pads 110, the plug housing 906, the plug body 908, the adhesive layer 910, a plug cap 912, and connection pad terminals 914.

[0050] Still referring to FIG. 9A-9B, and in greater detail, the connection pads 110 may be spaced apart by the dielectric material 902. In certain implementations, the dielectric material may be formed of any material with a relatively large dielectric constant. In certain implementations, the dielectric material may include parylene, fluoropolymer, atomic layer deposition, molecular vapor deposition, and the like materials. In some implementations, the dielectric material can be a polyimide material, for example a Kapton film, such as those supplied by DuPont of Wilmington, U.S.A. In some implementations, the thickness of the dielectric layer can be 25 mils. In certain implementations, the dielectric material may be 18 mils, 27 mils, or 30 mils.

[0051] Still referring to FIG. 9A-9B, and in greater detail, the connection pads 110 may have a rectangular shape. In some implementations, the connection pads 110 may be circular, polygonal, or irregular in shape. In some implementations, the connection pads 110 may be a conductive material, such as copper, gold, silver, or platinum. In some implementations, the connection pads 110 may be manufactured using any one of a number of inks manufactured by made by Applied Cavitation, Inc of Goleta, California. In some implementations, the connection pads 110 may have a thickness of 34 mils (34 / 1000 inches). In some implementations, the connection pads 110 may a thickness of 25 mils, 45 mils, or 50 mils. In some implementations, the connection pads 110 may have thickness approximately the diameter of a human hair. In some implementations, the connection pads 110 in electrical contact with the terminals of the stretchable, flexible substrate (not shown) may have a surface area sufficient to conduct an electrical current equal to or greater than 1 amp. In some implementations, the connection pads 110 in electrical contact with the terminals of the stretchable, flexible substrate (not shown) may have a surface area sufficient to conduct an electrical current of 2.5 amps, 4.0 amps, or 5.0 amps. Although two connection pads 110 are shown in FIG. 9 A, any number of connection pads 110 may be used to connect with theflexible, stretchable substrate. In some implementations, a plurality of plug housings 906 and plug bodies 908 may be connected and have electrical contact with any number of connection pads 110. In some implementations, the connection pads 110 are coupled at the plug body 908 with one or more plug pads 916 for soldering, pressure fit, or the like coupling. In some implementations, the connection pads 110 are on one side of the stretchable, flexible substrate and can make electrical contact with the terminals provided by the electronics on the stretchable, flexible substrate. In some implementations, the connection pads 110 are disposed on opposite sides of the stretchable, flexible substrate and can make electrical contact with the terminals provided by the electronics on the stretchable, flexible substrate.

[0052] Still referring to FIG. 9A-9B, the connection pads 110 may be continuously connected with connection pad terminals 914. In some implementations, the connection pad terminals 914 can pass through the plug cap 912 and be coupled to the plug pads 916. In some implementations, the length of the connection pad terminals 914 may be 0.1”, 0.25”, or 1”.

[0053] Still referring to FIG. 9A-9B, in some implementations, the adhesive layer 910 may be a rectangular frame aligned with the outermost edge of the connection pads 110 and the dielectric material 902. In some implementations, the adhesive layer 910 may be other shapes, such as a circular frame, a polygonal frame, or irregularly shaped frame. In some implementations, there may be a plurality of adhesive layers 910 arranged on the dielectric material. In some implementations, the adhesive layer 910 can partially cover the area where the dielectric material 902 is disposed. In some implementations, the adhesive layer 910 can completely cover the area where the dielectric material 902 is disposed.

[0054] In some implementations, the adhesive may be a phase change adhesive such as a hot melt adhesive that can adhere to the dielectric material 902, and the stretchable, flexible substrate (not shown). In some implementations, the adhesive may be an adhesive that flows on the dielectric material 902 with an application of heat. The adhesive then subsequentlycools and solidifies to form a bonded stack of elements including the dielectric material 902, the connection pads 110, and the terminals of the electronics on the flexible, stretchable substrate. Subsequently, this bonding permits a coupling or an intimate contact between the dielectric material 902, the connection pads 110, and the terminals of the electronics on the flexible, stretchable substrate. As a result of this coupling or intimate contact, the connection pads 110 and the terminals of the electronics on the stretchable, flexible substrate may move with respect to each other with minimal restriction. In some implementations, this intimate contact can permanently maintain electrical communication between the connection pads 110, an outside power source, and the electronics on the stretchable, flexible substrate. In some implementations, when the shape of the stretchable, flexible substrate is deformed (e.g., stretched), the electrical coupling between the connection pads 110 and the terminals of the flexible, stretchable substrate may be affected. In some of those implementations, the connection pads 110 may move with respect to the terminals of the stretchable, flexible substrate and the electronic coupling may be paused during substantial deformation of the shape of the substrate. In following, the conduction pads 110 may be configured to activate the electrical coupling once the flexible substrate returns to a defined operative state.

[0055] In addition, in some implementations, the adhesive may be tolerant of multiple wash cycles and mechanical manipulation (e.g., stretching) of the stretchable, flexible substrate. In some implementations, the adhesive can bond well to a variety of materials, such as polyester, polycotton, Lycra, polycarbonate, polyvinyl chloride, polyurethane, acrylonitrile butadiene styrene, wood, leather, fiberglass, aluminum, copper, and steel. In some implementations, the adhesive layer 910 may have a thickness of 0.001”, 0.002”, 0.004”, or 0.005”.

[0056] Still referring to FIG. 9A-9B, the plug body 908 can be enclosed at least partially within the plug housing 906 and covered by a plug cap 912 on one side. Although a pressurefit between the plug body 908, the plug housing 906, and the plug cap 912 are shown in the figure, any other securing mechanisms can be used to secure the plug assembly to the connection pads 110. In some implementations, alternate securing mechanics can be employed such as tabbed locking mechanisms to couple components of the plug assembly. The plug cap 912 can allow the connection pad terminals 914 to pass through the plug cap 912 and be coupled to the plug pads 916. In some implementations, the plug body can have a plug cover (not shown) to cover the opposite end of the plug body 908. The plug cover can enclose the exposed end of the plug body 908 and / or the plug housing 906 to create a watertight plug assembly including the plug body 908, the plug cap 912, the plug housing 906, and the plug cover. In some implementations, a section of the flexible, stretchable substrate and the connection pad terminals 914 may be enclosed in a watertight casing, such as the plug assembly and / or a watertight casing formed by the adhesive layer 910 shown in FIG. 9A-9B. In some implementations, such a watertight casing may include the connection pad terminals 914 and the connection pads 110. In some implementations, the connection pad terminals 914 may be absent from the apparatus 900. In those implementations, a watertight casing may include only the connection pads 110.

[0057] In some implementations, the watertight plug assembly may include a standard electrical connector, such as a standard plug, and watertight closure on the outside of the connection pads 110 and / or the flexible, stretchable electronics. In some implementations, a standard electrical connection can provide a way to disconnect the electronics outside of the watertight plug assembly. During use, a control circuit and a battery can be plugged into the plug connector. When not in use, the control circuit and battery can be unplugged, and a plug cover can be used to cover the exposed end of the plug body 908 where a standard electrical connector is accessed. The plug housing 906, the plug cap 912, and the plug cover may be formed from any suitable material that provides support for the plug body and facilitatesconnection to the connection pad terminals 914, In some implementations, the plug housing906, the plug cap 912, and the plug cover may be made of plastics such as polyethylene terephthalate, high-density polyethylene, polyvinyl chloride, low-density polyethylene, or polypropylene. In yet other implementations, the plug housing 906, the plug cap 912, and the plug cover may be made of rubber.

[0058] In some implementations, the plug body 908 may receive a corresponding plug receptacle which allows an electronic coupling between an external power source, the connection pads 110, and further conducts a current to the electronics disposed on the stretchable, flexible substrate. In some implementations, the plug body 908 may receive a USB-A, USB-C, or rectangular header plugs. In some implementations, the plug body 908 may receive barrel plugs with center pins and cantilever springs, EIAJ connectors, RCA type barrel plugs.

[0059] Referring now to FIG. 10, and in brief overview, an exploded view shows the alignment between a resistive heating element 1002 and one implementation of the apparatus 900 including the dielectric 902, the connections pads 110, the plug housing 906, the plug body 908, the adhesive layer 910, a plug cap 912 (not shown), connection pad terminals 914, a first opening 114, a second opening 118, and a channel 116. As shown in FIG. 10, the adhesive layer 910 defines a zig-zag path of the channel 116.

[0060] In some implementations, the connection pads 110 may be in intimate contact with the respective terminals of an additively manufactured resistive heating element as shown in FIG. 10. In some implementations, when the shape of the stretchable, flexible substrate is deformed (e.g., stretched), the electrical coupling between the connection pads 110 and the terminals of the flexible, stretchable substrate may be affected. In some of those implementations, the connection pads 110 may move with respect to the terminals of the stretchable, flexible substrate and the electronic coupling may be paused during substantialdeformation of the shape of the substrate. In following, the connection pads 110 may be configured to activate the electrical coupling once the flexible substrate returns to a defined operative state.

[0061] Still referring to FIG. 10, and in greater detail, the peripheral side of the adhesive layer 910 may define the first opening 114, the second opening 118, and the channel 116. In some implementations, the path of the channel may be zig-zag, wavy, straight, or any path that substantially reduces the access of water or moisture to the area where the connection pads 110 are in electrical contact with the terminals of the electronics on the flexible, electrical substrate. In some implementations, the first opening is through hole that may pass through one or more layers such as a polyimide layer (e.g., Kapton film), such as those supplied by DuPont of Wilmington, U.S.A, or other layers of the system until it reaches the flexible, stretchable substrate. The first opening can equalize the atmospheric pressure that is outside of the substrate and the pressure within the area of the electrical contact between the terminals of the stretchable, flexible substrate and the connection pads 110.

[0062] In some implementations, the second opening 118 may be covered by a gas- permeable material, to reduce access of water or moisture while allowing air and other gases to permeate through the gas-permeable material. The gas-permeable material may be affixed to the adhesive material. In some implementations, the coverage area of the gas-permeable material may extend beyond the second opening 118. In some implementations, the gas- permeable material may be 50% Gore-Tex, manufactured by W. L. Associates, Inc. of Newark, U.S.A. In some implementations, the gas-permeable material may be a water- resistant treated polyethene-based material, a water-resistant treated expanded polytetrafluorethylene-based material, nylon, or polyester. Although FIG. 10 depicts a specific orientation and position of the first opening 114, the second opening 118, and thechannel 116, other positions for the first opening 114, the second opening 118, and the channel 116 are possible.

[0063] In some implementations, a strain relief may be incorporated in the area where the terminals of the flexible, stretchable substrate, the connection pads 110, and / or the adhesive material are bonded with the flexible, stretchable substrate. In some implementations, a fabric or textile material may be used to cover some or all portions of the connection pads 110, the adhesive material, and / or other elements of the implementation of the apparatus.

[0064] Referring now to FIG. 11 , and in brief overview, the measured electrical resistance as a function of the number of stretch cycles of a smart textile having an electrical connection with the implementation of the apparatus of FIG. 10, wherein the smart textile is stretched to 20% elongation (15.2 mm displacement) at an elongation rate of 20% / s (15.2 mm / s), is shown. The smart textile used in the measurements shown in FIG. 11 were fabricated by forming a base film layer of thermoplastic polyurethane (TPU) on a fabric. In following, a fixed resistance stretchable heater ink was disposed on the TPU layer, and a stretchable printed silver conductor was disposed over the heat ink. Finally, the heating element was covered using a stretchable insulator ink.

[0065] The base TPU layer may be printed onto the fabric substrate and customized to satisfy the performance requirements for the smart textile. In some implementations, TPUs extruded with polyester provide resistance to chemical and oils while TPUs extruded with polyether TPUs offer flexibility and tear resistance. TPUs extruded with polycaprolactone are hydrolysis resistant and useful for applications with prolonged water exposure. In some implementations, the TPU film may include metals to provide a metallic color to the fabric. In still other implementations, the TPU film may include adjuvants to enhance antistatic properties.

[0066] In some implementations, the resistive elements are printed over the TPU layer. In some implementations, the resistive elements are printed using SE5025, a stretchable, resistive ink manufactured by Applied Cavitation Inc. of Goleta, California. SE5025 is designed for heating applications integrated onto elastomeric substrates. When cured, the ink has a prescribed resistance value and offers excellent flexibility and stretchability. SE5025 has superior adhesion to TPU and other elastomeric substrates.

[0067] In some implementations, the silver conductor is printed over the TPU film. In some implementations, the silver conductor and a busbar system are printed on the resistive elements. In some implementations, the silver conductor and the busbar system are printed using SEI 109, a stretchable, silver conductive ink manufactured by Applied Cavitation Inc. of Goleta, California. SEI 109 is a silver-filled conductor for printed interconnects for devices on elastomeric substrates. After drying, the ink has excellent conductivity and offers excellent elongation and flexibility. SEI 109 has superior adhesion to thermoplastic urethanes (TPU). SEI 109 can be used in stretchable electronics and e-textile applications to power components / devices and carry signals from embedded devices and sensors.

[0068] A stretchable carbon conductive element is disposed over the silver conductive elements. In some implementations, the carbon elements are printed on the silver conductive elements. In some implementations, the carbon elements are printed using SE1502, a stretchable, carbon conductor manufactured by Applied Cavitation Inc. of Goleta, California. SE1502 is a carbon filled conductor for printed circuitry and devices on elastomeric substrates. It can be dried at low temperatures to accommodate sensitive substrates and devices. After curing, the ink has good conductivity and offers excellent elongation and flexibility. SEI 502 limits silver migration when applied over silver traces.

[0069] In some implementations, the insulator layer is printed on the carbon conductive elements. In some implementations, insulator layer is printed using SE3104, a stretchable,printable insulator manufactured by Applied Cavitation Inc. of Goleta, California. SE3104 is a screen printable, thermally cured ink that is stretchable when cured. SE3104 can be used as an insulator and / or crossover dielectric. When cured, the ink displays exceptional durability, excellent flexibility, and high insulation resistance.

[0070] Over the silver conductor and busbar system is disposed an insulator layer. In some implementations, the insulator layer is printed on the silver traces. In some implementations, the insulator layer is printed using SE3104, a stretchable, printable insulator manufactured by Applied Cavitation Inc. of Goleta, California. SE3104 is a screen printable, thermally cured ink that is stretchable when cured. SE3104 can be used as an insulator and / or crossover dielectric. When cured, the ink displays exceptional durability, excellent flexibility, and high insulation resistance.

[0071] Smart textiles fabricated as described were tested to demonstrate their performance using a custom stretch testing machine capable of controlling elongation, elongation rate, and the number of stretch cycles. Smart textile samples were printed with a 200.0016 Stainless Steel Mesh and had dimensions of 76.2 mm x 2.00 mm (L x W). Three cases or conditions were tested and defined as follows: case 1 is SEI 109 printed on 4 mil TPU; case 2 is SEI 109 on 4 mil TPU with 3 layers of SE3104 insulator; and case 3 is SEI 109 on 4 mil TPU with 3 layers of SE3104 insulator, bonded to fabric with 3 mil hotmelt adhesive. A stretched resistance per cycle in ohms and an unstretched resistance per cycle in ohms was measure for each case tested as shown in FIG. 11.

[0072] The elongation tests were done for 2 additional elongations shown in FIG. 12 and FIG. 13. Referring now to FIG. 12, the measured electrical resistance as a function of the number of stretch cycles of a smart textile having an electrical connection with the implementation of the apparatus of FIG. 10, wherein the smart textile is stretched to 50% elongation (38.1 mm displacement) at an elongation rate of 20% / s (15.2 mm / s), is shown forcase 1. Referring now to FIG. 13, and in brief overview, the measured electrical resistance as a function of the number of stretch cycles of a smart textile having an electrical connection with the implementation of the apparatus of FIG. 10, wherein the smart textile is stretched to 100% (76.2 mm displacement) elongation at an elongation rate of 20% / s (15.2 mm / s), is shown.

[0073] Overall, FIGS. 11-13 demonstrate an increase in measured electrical resistance during stretching of the smart textile and minimum resistance measured during relaxation of the smart textile.

[0074] The effect of wash cycles on the measured electrical and power output of a smart textile was also measured. In the tests shown in FIGS. 14-16, a front load washer was used with the following settings and conditions: delicate cycle with a laundry bag, medium-low water temperature, unscented liquid laundry detergent, washed with delicate and cotton items, and hung to dry.

[0075] Referring now to FIG. 14, and in brief overview, the measured electrical resistance as a function of the number of wash cycles of a smart textile having an electrical connection with the implementation of the apparatus of FIG. 10 is shown. The measured electrical resistance after a number of wash cycles shows a persistent electrical resistance after 15 washes indicating that the connection between the connection pads 110, the connection pad terminals 914, the terminals of the smart textile were robust and maintained consistent electrical contact following washing.

[0076] Referring now to FIG. 15, and in brief overview, the power output of a heating element as a function of the number of wash cycles of a smart textile having an electrical connection with the implementation of the apparatus of FIG. 10 is shown. The measured power output after a number of wash cycles shows a power output after 15 washes indicating that the connection between the connection pads 110, the connection pad terminals 914, andthe terminals of the smart textile were robust and maintained consistent electrical contact following each wash cycle. As shown in FIG. 16, the corresponding infrared images of the heating element before washing and after the 15thwash are shown. The infrared images show shades of grey to indicate the temperature of the heating element, where the lighter grey areas indicate hotter temperatures and dark or black areas correspond to cooler temperatures. As can be seen in FIG. 16, the heating element is capable of reaching temperatures observed prior to washing even after 15 wash cycles.

[0077] The present disclosure describes an implementation of an apparatus for making an electrical connection to circuits disposed on flexible, stretchable substrates. The described implementation of an apparatus for making an electrical connection to heat pressed circuits, printed circuits is intended to create an electrical connection resistant to rigorous mechanical, electrical, thermal, and environmental stresses experienced by stretchable, flexible substrates, such as e-textiles or smart textiles, throughout their life cycle. The term “printed circuits” is intended to include circuits formed by all forms of printing and coating, including: premetered coatings such as patch die coating, slot or extrusion coating, slide or cascade coating, curtain coating; roll coating such as knife over roll coating, forward and reverse roll coating; gravure coating; dip coating; spray coating; meniscus coating; spin coating brush coating; air knife coating; screen printing processes; electrostatic printing processes; thermal printing processes; inkjet printing processes; direct write printing processes; jetted deposition processes and other similar techniques.

[0078] The interface where the terminals of flexible, stretchable substrates connect to a control circuitry or voltage source can be areas of mechanical and electrical failure. The described implementation of an apparatus for making an electrical connection to heat pressed circuits, printed circuits can serve various purposes, including shielding the terminal connection, mechanically fastening the connection, housing the terminal connector, andenabling external control of circuitry or voltage source. By way of example, the implementations of the present disclosure may be used with materials, such as crystalline film, that may be prone to damage using typical connectors that utilize clamping mechanisms.

[0079] By way of example, the implementations of the present disclosure may be implemented with smart textiles, including additively manufactured resistive heating elements, to supply power for the circuitry provided by the smart textile. In yet another example, the implementations of the present disclosure may be implemented with stretchable, flexible substrates containing light-emitting circuitry, sound-emitting circuitry.

[0080] The implementations of the present disclosure may be implemented with stretchable, flexible substrates and integrated with a variety of materials, including neoprene, leather, rubber, silicone, synthetic materials, polyester, or nylon. Furthermore, the implementations of the present disclosure may be implemented with stretchable, flexible substrates that may be integrated in fabric, outerwear, activewear, underclothes, base layers, gloves, socks, chairs for outdoor activities, wet suits, work gear, athletic gear. By way of example, the implementations of the present disclosure may also be integrated in therapeutic or medical items including in braces, wraps, pads, bedding and fabrics for pain management. The implementation of the apparatus may supply power for a stretchable, flexible substrate providing electrical muscle stimulation. Other applications may include military applications including implementation of the apparatus with circuits disposed on flexible, stretchable substrates in outerwear, gloves, seats, and other gear. Additional applications may include automotive applications including implementation of the apparatus with circuits disposed on flexible, stretchable substrates integrated in car seats, steering wheels, interior panels, and other areas of a car for defrosting or warming. In other applications, the implementation of the apparatus may supply power for stretchable, flexible substrates integrated in materialsintended for purposes of enabling entertainment, fashion, or art. Furthermore, by way of example the implementation of the apparatus may supply power for stretchable, flexible substrates with light-emitting and / or sound-emitting circuitry integrated in work gear used by police officers, medical personnel, or activewear worn by runners for purposes of increasing visibility of individuals in a number of settings, for example, low lit settings or high traffic areas. Combinations of any of the above are also included within the scope of the implementation of the apparatus for making an electrical connection to a circuit disposed on a flexible, stretchable substrate.

Claims

CLAIMS1. An apparatus for making an electrical connection to a circuit disposed on a flexible, stretchable substrate comprising: a support region; and a connection region foldably connected to the support region, the connection region including a plurality of connection pads each of the plurality of connection pads defining a slot in electrical communication with a conductive trace such that, when folded the connection pads are brought into electrical contact with a circuit disposed on a flexible, stretchable substrate.

2. The apparatus of claim 1, the connection pads defining a slot for receiving a ferrule.

3. The apparatus of claim 1, the conductive trace comprising a wire.

4. The apparatus of claim 3, the wire in contact with a ferrule and affixed to the slot.

5. The apparatus of claim 1, further comprising a plurality of adhesive windows.

6. The apparatus of claim 5, an adhesive disposed on the adhesive windows.

7. The apparatus of claim 1, the connection region having a smaller surface area than the support region.

8. The apparatus of claim 1, the connection region and the support region having identical edge profiles.

9. The apparatus of claim 1, the connection region and the support region defining an extending edge only on certain edges of the support region.

10. The apparatus of claim 1, further comprising a first opening for equalizing the pressure between the electrical contact of the connection pads and the flexible, stretchable substrate andatmospheric pressure.

11. The apparatus of claim 10, comprising an adhesive layer defining a channel in fluid communication with the first opening.

12. The apparatus of claim 11, the channel having a zig-zag path.

13. The apparatus of claim 11, further comprising a second opening in fluid communication with the channel.

14. The apparatus of claim 1, a gas permeable material disposed on the area between the connection pads.

15. A fabric comprising an apparatus of claim 1.

16. An article of clothing comprising an apparatus of claim 1.

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