Stretchable device

Abstract

Provided is a stretchable device comprising: a first stretchable member layer; stretchable wiring provided on the first stretchable member layer; and a second stretchable member layer covering the stretchable wiring. The stretchable wiring includes a first main surface in contact with the first stretchable member layer, and a second main surface in contact with the second stretchable member layer on a side opposite to the first main surface. In a cross-sectional view, each of the first main surface and the second main surface includes an inclined surface that is inclined such that the stretchable wiring tapers toward an edge of the stretchable wiring.

Description

stretchable devices

[0001] The present disclosure relates to stretchable devices.

[0002] Stretchable devices including a stretchable substrate have been known for some time. Stretchable devices can be used in, for example, living organisms or devices that require stretchability.

[0003] Japanese Patent Application Laid-Open No. 2017-117861

[0004] A stretchable device includes a resin stretchable substrate and stretchable wiring disposed on the stretchable substrate. A covering member that covers the stretchable wiring may also be provided to protect the stretchable wiring (Patent Document 1). Such a stretchable device is required to have high durability to prevent breakage of the stretchable wiring due to stresses generated during expansion and contraction.

[0005] The present disclosure has been made in view of the above-mentioned problems. That is, a main object of the present disclosure is to provide a stretchable device in which breakage of a stretchable wiring is suitably suppressed.

[0006] The inventors of the present application have come up with the invention of a stretchable device that achieves the above-mentioned main object.

[0007] A stretchable device according to one embodiment of the present disclosure comprises: a first stretchable material layer; a stretchable wiring provided on the first stretchable material layer; and a second stretchable material layer covering the stretchable wiring; wherein the stretchable wiring has a first main surface that contacts the first stretchable material layer and a second main surface that contacts the second stretchable material layer on the opposite side of the first main surface; and wherein, in a cross-sectional view, each of the first main surface and the second main surface includes an inclined surface that is inclined so that the stretchable wiring tapers toward an edge of the stretchable wiring.

[0008] According to the stretchable device according to an embodiment of the present disclosure, damage to the stretchable wiring is suitably suppressed.

[0009] FIG. 1 is a perspective view schematically showing the appearance of a stretchable device according to a first embodiment of the present disclosure. FIG. 2 is a cross-sectional view schematically showing the A-A cross section of the stretchable device of FIG. 1. FIG. 3 is an enlarged cross-sectional view schematically showing portion I of the stretchable device shown in FIG. 2. FIG. 4A is an enlarged cross-sectional view schematically showing a stretchable device according to a modified version of the first embodiment of the present disclosure. FIG. 4B is an enlarged cross-sectional view schematically showing a stretchable device according to a modified version of the first embodiment of the present disclosure. FIG. 5 is a perspective view schematically showing a stretchable device according to a modified version of the first embodiment of the present disclosure. FIG. 6 is an enlarged cross-sectional view schematically showing the B-B cross section of the stretchable device of FIG. 5. FIG. 7 is a cross-sectional view schematically showing a stretchable device according to a second embodiment of the present disclosure. FIG. 8 is a perspective cross-sectional view schematically showing a stretchable device according to a third embodiment of the present disclosure. FIG. 9 is a cross-sectional view schematically showing the C-C cross section of the stretchable device shown in FIG. 8. FIG. 10 is a perspective cross-sectional view schematically showing a stretchable device according to a fourth embodiment of the present disclosure.

[0010] The following describes specific embodiments of the present disclosure. The applicant provides the following description and examples to enable those skilled in the art to fully understand the present disclosure, and it should be noted that these are not intended to limit the subject matter described in the claims. In other words, the present disclosure is not particularly limited to the preferred embodiments described below, and can be implemented with appropriate modifications within the scope of its purpose. For convenience, the present disclosure may be divided into embodiments and examples to facilitate explanation or understanding of key points. However, partial substitution and / or combination of the configurations shown in different embodiments is possible. In describing such embodiments, redundant explanations of substantially identical features may be omitted, and only differences may be described. In particular, similar effects resulting from similar configurations may not be mentioned in each embodiment.

[0011] In this specification, the terms "thickness direction of the stretchable device" and "thickness direction of the stretchable wiring" can be used interchangeably. This direction corresponds to direction Y in the drawings.

[0012] As used herein, the terms "cross-sectional view" and "cross-sectional shape" refer to the shape of the stretchable device as viewed from a direction substantially perpendicular to the thickness direction of the stretchable device (in short, the shape of the stretchable device as cut along a plane parallel to the thickness direction of the stretchable device). Furthermore, as used herein, the term "planar view" refers to a sketch of the object as viewed from above or below along the thickness direction Y of the stretchable device.

[0013] Furthermore, in this specification, "above" an element includes not only the case of contacting the top surface of the element, but also the case of not contacting the top surface of the element. In other words, "above" an element does not only mean above the element, i.e., a position above the element via another object or a position above with a gap, but also a position directly above the element. Furthermore, "above" does not necessarily mean above in the vertical direction. "Above" merely indicates the relative positional relationship of an element.

[0014] The various numerical ranges referred to herein are intended to include the lower and upper numerical limits themselves unless otherwise specified, and the term "about" means that there may be a variation or difference of a few percent, for example, ±10%.

[0015] As used herein, "vertical" and "substantially vertical" do not necessarily mean completely "vertical," but include aspects that are slightly deviated from the completely vertical (for example, a range of ±10° from the completely vertical, e.g., a range of ±5°).

[0016] Furthermore, in this specification, "substantially parallel" does not necessarily mean completely "parallel," but includes a state where the parallelism is slightly deviated from the parallelism (for example, within a range of ±10° from completely parallelism, e.g., within a range of ±5°).

[0017] [Basic configuration of stretchable device] The structure of a stretchable device will be described with reference to Fig. 1. Fig. 1 is a perspective view illustrating an example of a stretchable device according to an embodiment of the present disclosure. Fig. 2 is a cross-sectional view schematically illustrating the A-A cross section of the stretchable device shown in Fig. 1. Note that cross-sectional views in this specification are cross sections parallel to the thickness direction Y of the stretchable device 1.

[0018] The stretchable device 1 comprises at least a stretchable material layer 12 and a stretchable wire 20. The stretchable wire 20 is disposed on the main surface of the stretchable material layer 12. Here, the "main surface" of the stretchable material layer refers to a surface that extends in a direction different from the thickness direction Y of the stretchable material layer, for example, a surface that extends in the Z-X direction that is approximately perpendicular to the thickness direction Y of the stretchable material layer. The "main surface" corresponds to a surface that is clearly larger in area than the other surfaces (side surfaces extending in the X-Y plane) of the sheet-like stretchable material layer. The stretchable material layer 12 may have a flat, sheet-like, or film-like shape, and may extend along the stretch direction of the stretchable device 1A. In such a structure, the main surface of the stretchable material layer 12 can also be interpreted as a surface that extends along the stretch direction of the stretchable material layer 12. Alternatively, it can also be interpreted as a surface that extends along the extension direction of the stretchable wire. Although the drawings show stretchable devices extending in a specific direction for clarity, the shape of the stretchable device is not particularly limited. The planar shape of the stretchable device is also not particularly limited, and can be, for example, a quadrilateral (e.g., square, rectangle, etc.), a polygon such as a triangle, a circle, an ellipse, a semicircle, a crescent, or an irregular shape.

[0019] The main components included in the stretchable device of the present disclosure will be described below with reference to FIGS. 1 and 2.

[0020] (Stretchable material layer 12) The stretchable material layer 12 (hereinafter also referred to as "stretchable substrate" or simply "substrate") may be a flat, sheet-like, or film-like stretchable material, and may be made of, for example, a resin material having stretchability. Here, in this specification, stretchability simply means the property of being able to stretch and contract, and can also be referred to as stretchability, stretchable, etc. More specifically, it means the property of being able to stretch from a non-stretched state, which is the normal state in which no tensile stress is applied, by applying tensile stress, and being able to contract when released from the stretched state.

[0021] (Stretchable Wiring 20) The stretchable device further includes a stretchable wiring 20 disposed on the stretchable material layer 12. The stretchable wiring 20 (hereinafter also simply referred to as "wiring") may contain conductive particles and a resin. Examples of the stretchable wiring 20 include a mixture of metal powder such as Ag (silver), Cu (copper), or Ni (nickel) as conductive particles and an elastomer resin such as a silicone resin. The average particle size of the conductive particles is not particularly limited, but is preferably 0.01 μm or more and 10 μm or less. Furthermore, the shape of the conductive particles is not particularly limited, but is preferably, for example, spherical.

[0022] Furthermore, for the sake of clarity, the drawings only show wires extending in a specific direction, but the stretchable wires 20 may extend in any direction on the main surface of the stretchable material layer 12. Preferably, the stretchable wires 20 may extend along the extension direction of the main surface of the stretchable material layer 12. Furthermore, when viewed from the thickness direction Y of the stretchable material layer 12, the stretchable wires 20 do not necessarily have to be arranged in a straight line, and may be arranged in a curved line, for example. Furthermore, when viewed from the thickness direction Y, the stretchable wires 20 do not necessarily have to extend in one direction. The number of stretchable wires 20 is not particularly limited, and one or more wires may be arranged.

[0023] (Stretchable material layer 14) The stretchable wiring 20 arranged on the stretchable material layer 12 may be covered by the stretchable material layer 14. In other words, the stretchable device further comprises a stretchable material layer 14, and the stretchable material layer 14 may cover the stretchable wiring 20 arranged on the stretchable material layer 12. In other words, the stretchable wiring 20 may be surrounded by the stretchable material layer 12 and the stretchable material layer 14. More specifically, the stretchable wiring 20 may comprise a first main surface 20a and a second main surface 20b opposing the first main surface 20a, with the stretchable material layer 12 located on the first main surface 20a side and the stretchable material layer 14 located on the second main surface 20b side. In such a structure, the stretchable material layer 12 may also be referred to as the "first stretchable material layer", the stretchable material layer 14 may also be referred to as the "second stretchable material layer", etc. Alternatively, the stretchable material layer 12 may be referred to as the "substrate," while the stretchable material layer 14 may be referred to as a "coating layer," a "protective layer," a "cover layer," etc. The second stretchable material layer 14, like the first stretchable material layer 12, may be a flat, sheet, or film-like stretchable material, and may be made of, for example, a stretchable resin material.

[0024] First Embodiment Based on the details of the main components of the stretchable device described above, the following describes the characteristic parts of the stretchable device according to the first embodiment of the present disclosure.

[0025] As shown in Figures 1 and 2, the stretchable device 1A of the present disclosure comprises a stretchable wire 20 sandwiched between a first stretchable material layer 12 and a second stretchable material layer 14. The stretchable wire 20 extending between the first stretchable material layer 12 and the second stretchable material layer 14 has a tapered shape at its edge in a cross-sectional view. The stretchable wire 20 may have a tapered shape at its edge extending along the extension direction of the stretchable wire 20. Alternatively, the stretchable wire 20 may have a tapered shape at its edge extending along the stretch direction of the stretchable device. In other words, the stretchable wire 20 may include a tapered portion at its edge. Preferably, the edge extending along the extension direction of the stretchable wire 20 is an edge having a tapered shape.

[0026] For example, when the stretchable wire 20 has a shape having a short side direction and a long side direction, such as a substantially rectangular or linear shape in plan view, the edge portion (which can also be referred to as a side edge portion) 22 extending along the long side direction of the stretchable wire 20 (direction Z in FIG. 1 ) may have a tapered shape in cross section, gradually becoming thinner. Below, a structure in which the stretchable wire 20 has a shape having a short side direction and a long side direction in plan view will be described as an example, but the features described below are not limited to cases in which the stretchable wire 20 has a substantially rectangular or linear shape. The stretchable wire 20 may have a shape that tapers along the short side direction X of the stretchable wire (width direction X in FIG. 1 ) by gradually reducing its thickness toward the side edge portion 22. The thickness of the stretchable wire 20 may gradually increase from the edge portion 22 toward the center of the stretchable wire 20, thereby forming a tapered shape at the edge portion 22. Specifically, each of the first main surface 20a and the second main surface 20b of the stretchable wiring 20 may have an inclined surface (22a, 22b) that is inclined so that the stretchable wiring 20 tapers toward the edge 22.

[0027] In this specification, "side edge portions of the stretchable wire" refers to edge portions located in the width direction X of the stretchable wire 20. On the other hand, "end edge portions of the stretchable wire" refers to edge portions located in the longitudinal direction Z of the stretchable wire. In other words, the edge portions of the stretchable wire 20 can be composed of side edge portions 22 located in the width direction X and end edge portions located in the longitudinal direction Z. The side edge portions 22 may extend along the longitudinal direction Z of the stretchable wire 20. Furthermore, the end edge portions may extend along the width direction X of the stretchable wire 20. In this specification, the term "along a direction" refers to a direction at an angle of less than 45° with respect to a predetermined direction (for example, direction X or direction Z). By providing the stretchable wire 20 with a cross-sectional shape that tapers at the edge portions 22, it is possible to achieve a structure in which the corners of the stretchable wire 20 that come into contact with the first stretchable material layer 12 and the second stretchable material layer 14 are cut out.

[0028] According to the above-described structure, each of the first stretchable material layer 12 and the second stretchable material layer 14 that surround the stretchable wire 20 is arranged along the inclined surfaces (22a, 22b) of the stretchable wire 20. In other words, the first stretchable material layer 12 and the second stretchable material layer 14 can be arranged so as to be in contact with the inclined surfaces (22a, 22b), respectively. This allows each of the first stretchable material layer 12 and the second stretchable material layer 14 to adhere more favorably to the outer contour of the stretchable wire 20, compared to when the cross-sectional shape of the stretchable wire 20 is a shape that includes corners, such as a rectangular shape. Therefore, peeling between the stretchable wire 20 and the stretchable material layers (12, 14) can be suppressed. Peeling between the stretchable wiring 20 and the stretchable material layer (12, 14) can cause stress to concentrate in areas where gaps are formed between the stretchable wiring 20 and the stretchable material layer (12, 14) due to the peeling, and can cause cracks or breakage due to the extension of the cracks, etc. According to the present disclosure, by suppressing peeling between the stretchable wiring 20 and the stretchable material layer (12, 14), damage such as cracks and breakage of the stretchable wiring 20 caused by the peeling can be suppressed.

[0029] Furthermore, if the edge 22 of the stretchable wiring 20 is not tapered and has a rectangular shape with corners, stress is likely to concentrate at the corners of the stretchable wiring 20 that come into contact with the first stretchable material layer 12 and the second stretchable material layer 14. When the first stretchable material layer 12 and the second stretchable material layer 14 are pressed together to form a stretchable device, the stretchable material layers (12, 14) may flow. If the stretchable wiring 20 has corners, the thickness of the stretchable material layers (12, 14) at the corners is likely to become locally thin due to the flow of the stretchable material layers. Therefore, when the stretchable device is stretched or contracted, there is a risk that the stretchable wiring 20 and / or the stretchable material layers (12, 14) will be damaged, starting from the corners. On the other hand, in the stretchable device 1A of the present disclosure, the stretchable wiring 20 has a cross-sectional shape that tapers at the edge 22, which makes it possible to more uniformly apply stress to the edge 22 of the stretchable wiring 20 and to suppress local concentration of stress. This makes it possible to suitably suppress damage to the stretchable wiring 20, the first stretchable material layer 12, and the second stretchable material layer 14 caused by stress concentration.

[0030] More specifically, the inclined surface 22a of the edge 22 on the first main surface 20a side of the stretchable wire 20 is inclined toward the second main surface 20b side. On the other hand, the inclined surface 22b of the second main surface 20b of the stretchable wire 20 is inclined toward the first main surface 20a side. A tapered edge 22 may be formed by such inclined surfaces 22a and 22b. As a result, the edge 22 may be formed with a convex shape that tapers in a direction intersecting the thickness direction Y of the stretchable wire 20. This structure can also be interpreted as a structure in which the side surface connecting the first main surface 20a and the second main surface 20b of the stretchable wire 20 is not a uniform plane, but has a shape that protrudes along the thickness direction of the stretchable wire 20.

[0031] FIG. 3 is an enlarged cross-sectional view schematically showing portion I of the stretchable device 1A shown in FIG. 2. FIGS. 4A and 4B are enlarged cross-sectional views schematically showing modified forms of the cross-sectional shape of the edge portion 22. As shown in FIG. 3, the inclined surfaces (22a, 22b) forming the convex-shaped edge portion 22 may be curved surfaces. Because the inclined surfaces (22a, 22b) are curved surfaces, the edge portion 22 may have a curved outer contour, such as an arc-like shape, in cross-section. In such a configuration, the stretchable wire 20 may have an elliptical cross-sectional shape or an oblong cross-sectional shape having a major axis substantially parallel to the extension direction of the stretchable wire 20. Alternatively, as shown in FIG. 4A, a pair of arc-shaped inclined surfaces (22a, 22b) converging to a tip 23 of the convex shape may face each other, thereby forming the edge portion 22 having a substantially almond-shaped cross-sectional shape.

[0032] Alternatively, as shown in FIG. 4B , the inclined surfaces (22a, 22b) forming the convex edge portion 22 may be flat. Here, "flat" means a flat surface without any curves in a cross-sectional view cut in a direction perpendicular to the extension direction of the surface. However, it does not necessarily have to be completely flat, as long as it is flat from a macroscopic perspective. In other words, the surface may have fine irregularities from a microscopic perspective. The inclined surfaces (22a, 22b) may be flat surfaces that are inclined with respect to the extension direction of the stretchable wiring 20 so that the edge portion 22 tapers. According to this structure, in a cross-sectional view, the outer contour of the edge portion 22 may have a shape that protrudes in an approximately V-shape in a direction perpendicular to the thickness direction Y.

[0033] The inclined surfaces (22a, 22b) may also include a plurality of inclined surfaces that are inclined so that the edge portion 22 has a tapered shape. For example, the inclined surfaces (22a, 22b) may be surfaces that include a plurality of flat surfaces with different inclination angles, a plurality of curved surfaces with different curvatures, or a combination of flat and curved surfaces.

[0034] The tip 23 of the edge portion 22 having a convex shape may be located on the first covering member layer 12 side or the second covering member layer 14 side with respect to a center line P that passes through the center of the stretchable wire 20 and is perpendicular to the thickness direction Y of the stretchable wire 20, or may be located on the center line P. The center line P can also be interpreted as a line that bisects the thickness of the stretchable wire 20. In one aspect, the edge portion 22 of the stretchable wire 20 may be tapered so that the tip 23 of the convex shape is located on the center line P. In such a structure, each of the first main surface 20a and the second main surface 20b may be inclined toward the center line P at the edge portion 22 to form a convex edge portion 22. According to such a structure, the stretchable wire 20 is inclined more evenly on both the first main surface 20a side and the second main surface 20b side, so that the stress applied to both the first main surface 20a side and the second main surface 20b side can be made more uniform. This more suitably reduces the concentration of stress that accompanies the stretching of the stretchable device 1A, making it possible to suppress breakage of the stretchable wiring 20.

[0035] As shown in FIG. 2 , the stretchable wire 20 has a structure in which the thickness is gradually reduced in a peripheral region 24 of the stretchable wire 20, including the edge portion 22. On the other hand, in a central region 27 excluding the peripheral region 24, the stretchable wire 20 may have a substantially constant thickness. This means that the stretchable wire 20 has a portion where the thickness gradually decreases only in the peripheral region 24. By having a tapered shape in the edge portion 22 and a substantially constant thickness in the central region 27, damage to the stretchable wire 20 can be suppressed without excessively reducing the cross-sectional area of ​​the stretchable wire 20. Therefore, according to the above-described configuration, damage to the stretchable wire 20 can be suppressed without excessively increasing the resistance value of the stretchable wire 20. Note that, as shown in FIG. 2 , the peripheral region 24 may also include a region where the thickness of the stretchable wire 20 is substantially constant.

[0036] The edge portion 22 may have a substantially symmetrical shape in cross-sectional view. Specifically, the cross-sectional shape of the edge portion 22 may be line-symmetric with respect to the center line P of the stretchable wiring 20. In other words, the edge portion 22 may have a line-symmetrical cross-sectional shape with the center line P of the stretchable wiring 20 as the axis of symmetry. In such a structure, the center line P may coincide with a line that bisects the tapering angle of the edge portion 22. By having the edge portion 22 have a line-symmetrical cross-sectional shape, the stress acting on the edge portion 22 can be made more uniform. This makes it possible to more suitably suppress damage to the stretchable wiring 20 when the stretchable device is stretched.

[0037] Furthermore, with this structure, the contact area between the stretchable material layer and the stretchable wire 20 on the first principal surface 20a side of the stretchable wire 20 can be made substantially the same as the contact area between the stretchable material layer and the stretchable wire 20 on the second principal surface 20b side. That is, the stretchable wire 20 can be in contact with the stretchable material layer on both the first principal surface 20a side and the second principal surface 20b side with substantially the same contact area. With this structure, the degree of stretch of the stretchable material layer (12, 14) around the stretchable wire 20 can be made more uniform. This can reduce bias in the shear stress distribution at the interface between the stretchable wire 20 and the stretchable material layer (12, 14). Therefore, even when stress is generated during elongation of the stretchable device 1A, the close contact state between the stretchable wire 20 and the stretchable material layer (12, 14) can be suitably maintained.

[0038] In one aspect, the stretchable wire 20 may have a cross-sectional shape that is symmetrical with the center line P as the axis of symmetry. Alternatively, or additionally, the stretchable wire 20 may have a cross-sectional shape that is symmetrical with the axis of symmetry being a center line that passes through the center of the stretchable wire 20 and is along the thickness direction Y of the stretchable wire 20 (i.e., a line perpendicular to the center line P). In such a structure, both of a pair of edge portions 22 that are arranged opposite each other in the extension direction of the stretchable wire 20 have the same tapered shape. This makes it possible to make the stress acting on the stretchable wire 20 more uniform as a whole, and stress concentration can be suitably suppressed.

[0039] The first elastic member layer 12 and the second elastic member layer may be in contact with each other via an adhesive layer or the like. Alternatively, a layer such as an adhesive layer may not be disposed between the first elastic member layer 12 and the second elastic member layer 14. In other words, the first elastic member layer 12 and the second elastic member layer 14 may be in direct contact with each other. The stretchable device of the present disclosure can have suitable peel resistance by having the elastic member layers in direct contact and bonded to each other, without having an adhesive layer that may trigger peeling in some cases.

[0040] The first elastic material layer 12 and the second elastic material layer 14 may be integrated with each other around the elastic wire 20. The first elastic material layer 12 and the second elastic material layer 14 may be configured as an integral unit around the elastic wire 20. In such a configuration, the first elastic material layer 12 and the second elastic material layer 14 may be continuous with each other. For example, no interface may be formed between the first elastic material layer 12 and the second elastic material layer 14 around the elastic wire 20. In other words, around the elastic wire 20, the first elastic material layer 12 and the second elastic material layer 14 can be considered to be a single elastic member that is continuous with each other.

[0041] In such a configuration, the stretchable device 1A may include a stretchable member having a structure branched at the edge 22 of the stretchable wire 20. The stretchable wire 20 may be covered by a first stretchable member layer 12 and a second stretchable member layer 14 branched at the edge 22 of the stretchable wire 20. In a cross-sectional view, the stretchable member may have a continuous structure that branches into the first stretchable member layer 12 and the second stretchable member layer 14 starting from one edge 22 side of the stretchable wire 20 and then merges again at the other edge 22 side. In short, the stretchable wire 20 may be surrounded by a single stretchable member. Such a structure can also be interpreted as a structure in which the stretchable wire 20 is positioned inside the stretchable member. In this way, by having a structure in which the first elastic material layer 12 and the second elastic material layer 14 are integrated with each other, an elastic device with better peel resistance between the first elastic material layer 12 and the second elastic material layer 14 can be obtained.

[0042] The material used for each of the first stretchable material layer 12 and the second stretchable material layer 14 is preferably a thermoplastic elastomer. More preferably, it is a thermoplastic elastomer with an elongation rate of 500% or more. The elongation rate can be a value measured in accordance with JIS K6251 (2017), for example.

[0043] The thermoplastic elastomer material may be, for example, one or more materials selected from the group consisting of styrene-based elastomers, urethane-based elastomers, vinyl chloride-based elastomers, ester-based elastomers, acrylic-based elastomers, and amide-based elastomers. When emphasis is placed on stretchability as a stretchable device, each of the first stretchable material layer 12 and the second stretchable material layer 14 is preferably a styrene-based elastomer or a urethane-based elastomer.

[0044] Examples of styrene-based elastomers include styrene-isoprene-styrene block copolymer (SIS), styrene-butadiene-styrene block copolymer (SBS), styrene-ethylene-propylene-styrene block copolymer (SEPS), and styrene-isobutylene-styrene block copolymer (SIBS).

[0045] The first stretchable material layer 12 and the second stretchable material layer 14 may be made of the same material. More specifically, the first stretchable material layer 12 and the second stretchable material layer 14 may be made of a thermoplastic elastomer material of the same composition. In other words, stretchable material layers (12, 14) made of the same thermoplastic elastomer material may be disposed on each of the first main surface 20a side and the second main surface 20b side of the stretchable wiring 20. By making the first stretchable material layer 12 and the second stretchable material layer 14 of the same material, the stretchable wiring 20 can have the same degree of stretchability on the first main surface 20a side and the second main surface 20b side. This makes the stretchability of the entire stretchable device more uniform, and can reduce stress concentration associated with stretching. Therefore, peeling between the stretchable wiring 20 and the stretchable material layer (12, 14) caused by the stress concentration, as well as damage to the stretchable wiring 20 and / or the stretchable material layer (12, 14) can be suitably suppressed.

[0046] When prioritizing the insulation of the stretchable wiring 20, the thickness T1 of the first stretchable material layer 12 and the thickness T2 of the second stretchable material layer 14 (see FIG. 7 ) are each preferably 10 μm or more, more preferably 20 μm or more, and even more preferably 30 μm or more. Note that thicknesses T1 and T2 refer to the thickness of a region that overlaps with the central region 27 (see FIG. 2 ) of the stretchable wiring 20 when viewed from the thickness direction Y of the stretchable wiring 20. When prioritizing the stretchability of the device, the thicknesses (T1, T2) of the first stretchable material layer 12 and the second stretchable material layer 14 are each preferably 1 mm or less, more preferably 100 μm or less, and even more preferably 50 μm or less. Furthermore, the first stretchable material layer 12 and the second stretchable material layer 14 may each have the same thickness, or may have different thicknesses.

[0047] FIG. 5 is a perspective view schematically showing a stretchable device according to a modified example of the first embodiment of the present disclosure. FIG. 6 is an enlarged cross-sectional view schematically showing the B-B cross section of the stretchable device of FIG. 5. The features related to the shape of the edge portion 22 of the stretchable wire 20 of the stretchable device of the present disclosure described above or below may be the same not only for the side edge portion 22 extending along the longitudinal direction Z of the stretchable wire 20, but also for the end edge portion 25 extending along the width direction X (see FIGS. 5 and 6 ). That is, in the stretchable device of the present disclosure, the stretchable wire 20 may have the above-described tapered shape at the end edge portion 25 extending along the width direction X, in addition to the side edge portion 22 extending along the longitudinal direction Z, or instead of the side edge portion 22. That is, the stretchable wire 20 may have inclined surfaces (25a, 25b) that form a tapered shape at the end edge portion 25. For example, a tapered shape may be formed along the periphery including the side edge portions 22 and end edge portions 25 of the stretchable wiring 20. In other words, the stretchable wiring 20 may have an edge portion 22 that is tapered along the entire periphery. This further reduces stress concentration that may occur at the end edge portions 25 in addition to the side edge portions 22 of the stretchable wiring 20, and may make it possible to more suitably suppress breakage of the stretchable device.

[0048] [Second embodiment] Next, a description will be given of a stretchable device according to a second embodiment. The stretchable device according to the second embodiment differs from the stretchable device according to the first embodiment in that the first stretchable material layer 12 and the second stretchable material layer 14 are each raised in an area that overlaps with the stretchable wiring 20 in a plan view.

[0049] 7 is a cross-sectional view schematically showing a stretchable device 1B according to a second embodiment. As shown in the figure, the first stretchable material layer 12 and the second stretchable material layer 14 surrounding the stretchable wire 20 may have regions that overlap with the stretchable wire 20 protruding in a direction away from the stretchable wire 20 in a planar view. In other words, the first stretchable material layer 12 and the second stretchable material layer 14 may each have a protruding portion that protrudes toward the outside of the stretchable device in a region that overlaps with the stretchable wire 20 in a planar view. The first stretchable material layer 12 and the second stretchable material layer 14 may each have a convex shape that protrudes in a direction away from the stretchable wire along the thickness direction of the stretchable wire. The first stretchable material layer 12 and the second stretchable material layer 14 may each protrude in opposite directions.

[0050] In this structure, the stretchable device 1B has an increased overall thickness in the region where the stretchable wiring 20 is arranged, while the overall thickness is reduced in the region where the stretchable wiring 20 is not arranged. In other words, the stretchable device 1B does not have a constant thickness throughout, and the region that does not overlap with the stretchable wiring 20 may have a smaller thickness than the region that overlaps with the stretchable wiring 20. With this configuration, the cross-sectional area of ​​the stretchable device is reduced compared to an embodiment in which the stretchable device has a uniform thickness throughout (for example, the stretchable device 1A shown in FIG. 2 ). The smaller the thickness and cross-sectional area of ​​the stretchable device, the less the load required for elongation is, and therefore the more excellent the stretchability of the stretchable device. Therefore, the stretchable device 1B of the present disclosure can have suitable stretchability while suppressing breakage of the stretchable wiring 20.

[0051] Each of the first stretchable material layer 12 and the second stretchable material layer 14 may have substantially the same thickness in an area that overlaps with the stretchable wire 20 in a planar view and an area that does not overlap with the stretchable wire 20. The raised shape of each of the first stretchable material layer 12 and the second stretchable material layer 14 may correspond to the cross-sectional shape of the stretchable wire 20 disposed therein. That is, the raised surface of each of the first stretchable material layer 12 and the second stretchable material layer 14 may have a gently sloping surface that follows the sloping surfaces (22a, 22b) of the stretchable wire 20. With this structure, the first stretchable material layer 12 and the second stretchable material layer 14 gently swell, thereby suitably dispersing stress acting on the portions that are the starting points of the swell. This can suppress damage to the first stretchable material layer 12 and the second stretchable material layer 14.

[0052] The first elastic member layer 12 and the second elastic member layer 14 may each extend along the tapered edge 22 of the elastic wire 20. In such a structure, the first elastic member layer 12 and the second elastic member layer 14 may extend so as to gradually approach each other from the center side towards the edge side of the elastic wire 20. In other words, the distance between the first elastic member layer 12 and the second elastic member layer 14 may gradually decrease from the center side towards the edge side of the elastic wire 20. The first elastic member layer 12 and the second elastic member layer 14 may be in contact with each other around the periphery of the elastic wire 20. More specifically, the first elastic member layer 12 and the second elastic member layer 14 may be in contact with and adhered to each other on the outside of the edge 22.

[0053] The above-described structure makes it possible to further reduce the contact angle between the first stretchable material layer 12 and the second stretchable material layer 14 around the edge 22 of the stretchable wire 20. The contact angle corresponds to the angle formed by the first stretchable material layer 12 and the second stretchable material layer 14 that surround the edge 22 of the stretchable wire 20, and can also be interpreted as the branching angle of the stretchable material layers. By having the first stretchable material layer 12 and the second stretchable material layer 14 contact each other at a smaller angle (for example, an angle less than 90 degrees), the adhesive strength between the stretchable material layers can be improved. Therefore, peeling between the first stretchable material layer 12 and the second stretchable material layer 14 is suitably suppressed, and damage to the stretchable wire 20 and the stretchable material layers (12, 14) due to such peeling can be suppressed.

[0054] [Third embodiment] Next, a description will be given of a stretchable device according to a third embodiment. In the stretchable device according to the third embodiment, the second stretchable material layer 14 is disposed in at least a region overlapping with the stretchable wiring 20.

[0055] FIG. 8 is a perspective cross-sectional view schematically showing a stretchable device 1C according to a third embodiment of the present disclosure. FIG. 9 is a cross-sectional view schematically showing the C-C cross section of the stretchable device 1C shown in FIG. 8. As shown in the figure, the second stretchable material layer 14 located on the second main surface 20b side of the stretchable wiring 20 does not necessarily have to be provided over the entire surface of the stretchable device 1C in a planar view. The second stretchable material layer 14 is provided so as to cover the stretchable wiring 20, but does not have to be provided in regions where the stretchable wiring 20 is not provided. That is, the stretchable device 1C may have, in a planar view, a region where the second stretchable material layer 14 is provided and a region where the second stretchable material layer 14 is not provided. In a planar view, the second stretchable material layer 14 is provided in at least a region that overlaps with the stretchable wiring 20.

[0056] According to the above-described structure, the cross-sectional area of ​​the stretchable device is reduced compared to a structure in which the second stretchable material layer 14 is provided over the entire surface of the stretchable device. This reduces the load acting on the stretchable material layer and the stretchable wiring when the stretchable device is stretched, and therefore it is possible to obtain a stretchable device with a reduced risk of breakage due to stretching.

[0057] The second stretchable material layer 14 may be arranged so as to cover at least the second main surface 20b and edge portions 22 of the stretchable wire 20. As shown in Figure 9, the second stretchable material layer 14 may extend to the periphery of the stretchable wire 20 so as to continuously cover the second main surface 20b and the edge portions 22. The first stretchable material layer 12 may be in contact with the second stretchable material layer 14 that has extended to the periphery of the stretchable wire 20. In a cross-sectional view, the width dimensions (Ws1, Ws2) of the second stretchable material layer 14 extending around the stretchable wire 20 may be greater than or equal to the thickness T2 of the second stretchable material layer located on the second main surface 20b of the stretchable wire 20. The width dimensions (Ws1, Ws2) can also be interpreted as the width of the second stretchable material layer 14 that protrudes from the stretchable wire 20 when viewed in the thickness direction Y. That is, the width dimension Ws of the second stretchable material layer 14 may be equal to or greater than (width dimension Wc of the stretchable wire) + (thickness T2 of the second stretchable material layer × 2). When the width dimension Ws of the second stretchable material layer 14 is equal to or greater than the above-mentioned dimension, the stretchable wire 20 can be suitably protected by the first stretchable material layer 12 and the second stretchable material layer 14.

[0058] The width dimensions Ws1 and Ws2 of the second stretchable material layer 14 that contact the first stretchable material layer 12 on opposite sides of the stretchable wiring 20 may be the same as each other, or may be different from each other. In other words, the width dimension Ws1 of the second stretchable material layer 14 that contacts the first stretchable material layer 12 on one edge portion 22 side may be different from the width dimension Ws2 of the second stretchable material layer 14 that contacts the first stretchable material layer 12 on the other edge portion 22 side that is located on the opposite side of the edge portion 22 in the direction perpendicular to the thickness direction Y. Furthermore, the width dimensions Ws1 and Ws2 do not necessarily have to be constant along the extension direction of the stretchable wiring 20.

[0059] [Fourth embodiment] Next, a description will be given of a stretchable device according to a fourth embodiment. The stretchable device according to the fourth embodiment differs from the stretchable device according to the first embodiment in that the stretchable wiring 20 is exposed in a partial region.

[0060] FIG. 10 is a perspective cross-sectional view schematically illustrating a stretchable device 1D according to a fourth embodiment. The stretchable wiring 20 arranged in the stretchable device 1D includes a stretchable region Q1 that is stretchable and a non-stretchable region Q2 that is less stretchable than the stretchable region. In this specification, the "non-stretchable region" refers to a region that is less stretchable than the stretchable region Q1, as described above, and is not necessarily limited to a region that has no stretchability at all. In other words, the non-stretchable region Q2 may have lower stretchability than the stretchable region Q1. The non-stretchable region Q2 may be, for example, a connection point between the stretchable wiring 20 and other wiring and / or electronic components, and / or an intersection point between multiple stretchable wirings 20. For this reason, the non-stretchable region Q2 may also be referred to as, for example, a "high hardness region," a "low stretchable region," a "connection region," or a "component placement region."

[0061] The second stretchable material layer 14 covers the stretchable wiring 20 in the stretchable region Q1, but does not have to cover the stretchable wiring 20 in the non-stretchable region Q2. In other words, the second main surface 20b side of the stretchable wiring 20 may be exposed in the non-stretchable region Q2. With this configuration, damage to the stretchable wiring 20 due to stretching of the stretchable wiring 20 is suitably suppressed in the stretchable region Q1, while electrical conduction and signal input / output with other wiring and / or electronic components is possible in the non-stretchable region Q2. Furthermore, by selectively providing the second stretchable material layer 14 only in the stretchable region Q1, the stretchability in the stretchable region Q1 is limited, making it possible to make the amount of stretch of the entire stretchable device including the stretchable region Q1 and the non-stretchable region Q2 closer to uniform.

[0062] The cross-sectional shape of the stretchable wire 20 may be different in the stretchable region Q1 and the non-stretchable region Q2. For example, in the stretchable region Q1, the stretchable wire 20 has a structure in which the edge 22 is tapered, as shown in FIG. 9 . On the other hand, in the non-stretchable region Q2, the stretchable wire 20 may not have a tapered edge 22, and may have a substantially constant thickness, for example, from the center to the edge 22. Alternatively, in the stretchable region Q1, inclined surfaces may be provided on both sides of the first main surface 20a and the second main surface 20b, while in the non-stretchable region Q2, only one of the first main surface 20a and the second main surface 20b may be inclined. The stretchable device 1D may include a stretchable wire 20 including the tapered edge 22 described above in at least the stretchable region Q1.

[0063] Furthermore, the cross-sectional shape of the first stretchable material layer 12 may be different in the stretchable region Q1 and the non-stretchable region Q2. For example, in the stretchable region Q1, the first stretchable material layer 12 has a raised structure in a region that overlaps with the stretchable wiring 20 in a planar view, as shown in Fig. 9 . On the other hand, in the non-stretchable region Q2, the degree of protrusion may be smaller than in the stretchable region Q1, or the non-stretchable region Q2 may be a flat surface that does not include any protrusions. The stretchable device 1D may have a first stretchable material layer 12 that includes the above-mentioned protrusions in at least the stretchable region Q1.

[0064] (Method for Producing a Stretchable Device) An exemplary method for producing a stretchable device according to an embodiment of the present disclosure will now be described.

[0065] First, prepare the first stretchable material layer 12. After the first stretchable material layer 12 is prepared, the stretchable wiring 20 is formed on the main surface of the first stretchable material layer 12.

[0066] The stretchable wiring 20 may be formed by printing a conductive paste (for example, a conductive paste containing a mixture of silver and resin) onto the first stretchable material layer 12 using screen printing, inkjet printing, or the like. This allows a desired circuit pattern to be obtained. For example, the edge 22 may be formed to have a tapered shape by controlling the printing pattern. Alternatively, the edge 22 of the stretchable wiring 20 may be formed to have a tapered shape in a subsequent pressing step.

[0067] After forming the circuit pattern of the stretchable wiring 20 on the first stretchable material layer 12, the conductive paste is dried and hardened, thereby forming the stretchable wiring 20 on the first stretchable material layer 12. Note that it is also possible to mount components such as sensors, if necessary.

[0068] Next, a device precursor is formed by stacking the second stretchable material layer 14 in the thickness direction Y so as to cover the stretchable wiring 20 arranged on the first stretchable material layer 12. Next, the device precursor may be pressed under predetermined temperature conditions, for example, to bond the stacked first stretchable material layer 12 and second stretchable material layer 14 together. At this time, the first stretchable material layer 12 and the second stretchable material layer 14 may be caused to flow along the shape of the stretchable wiring 20, thereby causing the first stretchable material layer 12 and the second stretchable material layer 14 to bulge in areas that overlap with the stretchable wiring 20 in a planar view. Alternatively, the first stretchable material layer 12 and the second stretchable material layer 14 may be welded together to obtain a stretchable member in which the first stretchable material layer 12 and the second stretchable material layer 14 are integrated with each other. In this manner, a stretchable device according to an embodiment of the present disclosure may be obtained.

[0069] Although the embodiments of the present disclosure have been described above, they are merely typical examples. Those skilled in the art will readily understand that the present disclosure is not limited thereto, and that various modifications are possible within the scope of the present disclosure.

[0070] It should be noted that one embodiment of the present disclosure as described above includes the following preferred aspects. <1> A stretchable device comprising a first stretchable material layer, a stretchable wiring provided on the first stretchable material layer, and a second stretchable material layer covering the stretchable wiring, wherein the stretchable wiring has a first main surface in contact with the first stretchable material layer and a second main surface opposite to the first main surface in contact with the second stretchable material layer, wherein, in a cross-sectional view, each of the first main surface and the second main surface includes an inclined surface that is inclined so that the stretchable wiring tapers toward an edge of the stretchable wiring. <2> The stretchable device according to <1>, wherein, in a cross-sectional view, the edge of the stretchable wiring has a convex shape that tapers toward a direction intersecting the thickness direction of the stretchable wiring. <3> The stretchable device according to <2>, wherein a tip of the convex shape is located on a center line that passes through the center of the stretchable wiring and is perpendicular to the thickness direction of the stretchable wiring. <4> The stretchable device according to any one of <1> to <3>, wherein the inclined surface comprises a curved surface. <5> The stretchable device according to any one of <1> to <4>, wherein the stretchable wiring comprises a peripheral region including the edge portion and a central region excluding the peripheral region, and wherein the thickness of the stretchable wiring is constant in the central region and gradually decreases in the peripheral region towards the edge portion. <6> The stretchable device according to any one of <1> to <5>, wherein, in a cross-sectional view, the edge portion of the stretchable wiring is line-symmetrical with respect to a center line that passes through the center of the stretchable wiring and is orthogonal to the thickness direction of the stretchable wiring. <7> The stretchable device according to any one of <1> to <6>, wherein the stretchable wiring has a shape in a plan view that has a short side direction and a long side direction, and wherein, in a cross-sectional view, each of the first main surface and the second main surface comprises an inclined surface that is inclined so that the stretchable wiring tapers towards an edge portion extending along the long side direction of the stretchable wiring. <8> The stretchable device according to <7>, wherein, in a cross-sectional view, each of the first main surface and the second main surface further includes an inclined surface that is inclined so that the stretchable wiring tapers toward an edge portion extending along a short-side direction of the stretchable wiring. <9> The stretchable device according to any one of <1> to <8>, wherein at least one of the first stretchable material layer and the second stretchable material layer has a portion that protrudes along a thickness direction of the stretchable wiring.<10> The stretchable device according to any one of <1> to <9>, wherein each of the first stretchable material layer and the second stretchable material layer has a portion that protrudes outward along the thickness direction of the stretchable wire. <11> The stretchable device according to any one of <1> to <10>, wherein, in a cross-sectional view, the first stretchable material layer and the second stretchable material layer gradually approach each other from the center side toward the edge side of the stretchable wire. <12> The stretchable device according to any one of <1> to <11>, wherein the first stretchable material layer and the second stretchable material layer are made of a thermoplastic resin. <13> The stretchable device according to any one of <1> to <12>, wherein the first stretchable material layer and the second stretchable material layer are made of the same material. <14> The stretchable device according to any one of <1> to <13>, wherein the first stretchable material layer and the second stretchable material layer are directly bonded to each other around the stretchable wire. <15> The stretchable device according to any one of <1> to <14>, wherein the first stretchable material layer and the second stretchable material layer are integrated with each other around the stretchable wiring. <16> The stretchable device according to any one of <1> to <15>, wherein the stretchable wiring is surrounded by a stretchable member branched into the first stretchable material layer and the second stretchable material layer. <17> The stretchable device according to any one of <1> to <16>, wherein, when viewed in the thickness direction of the stretchable wiring, the stretchable wiring comprises a stretchable region and a non-stretchable region, and the second stretchable material layer covers at least the stretchable region of the stretchable wiring in the thickness direction of the stretchable wiring. <18> The stretchable device according to <17>, wherein the stretchable wiring in the stretchable region and the stretchable wiring in the non-stretchable region have mutually different cross-sectional shapes. <19> The stretchable device according to any one of <1> to <18>, wherein, in a cross-sectional view, the width dimension of the second stretchable material layer in the width direction of the stretchable wire is equal to or greater than the sum of the width dimension of the stretchable wire and twice the thickness dimension of the second stretchable material layer. <20> The stretchable device according to any one of <1> to <19>, wherein the thickness dimension of each of the first stretchable material layer and the second stretchable material layer is 10 μm or greater.

[0071] The above effects are merely exemplary, and the present disclosure is not limited to the above, and additional effects may also be provided.

[0072] 1A to 1D: Stretchable device 12: First stretchable material layer 14: Second stretchable material layer 20: Stretchable wiring 20a: First main surface 20b: Second main surface 22: Edge portion 22a, 22b: Inclined surface 23: Tip of edge portion 24: Peripheral region 25: End portion 25a, 25b: Inclined surface 27: Central region

Claims

1. A stretchable device comprising a first stretchable material layer, a stretchable wiring provided on the first stretchable material layer, and a second stretchable material layer covering the stretchable wiring, wherein the stretchable wiring has a first main surface that contacts the first stretchable material layer and a second main surface that contacts the second stretchable material layer on the opposite side to the first main surface, and wherein, in a cross-sectional view, each of the first main surface and the second main surface includes an inclined surface that is inclined so that the stretchable wiring tapers towards an edge of the stretchable wiring.

2. The stretchable device according to claim 1, wherein, in a cross-sectional view, the edge of the stretchable wiring has a convex shape that tapers in a direction intersecting the thickness direction of the stretchable wiring.

3. The stretchable device according to claim 2, wherein the tip of the convex shape is located on a center line that passes through the center of the stretchable wiring and is perpendicular to the thickness direction of the stretchable wiring.

4. The stretchable device of any one of claims 1 to 3, wherein the inclined surface comprises a curved surface.

5. The stretchable device according to any one of claims 1 to 4, wherein the stretchable wiring comprises a peripheral region including the edge portion and a central region excluding the peripheral region, and the thickness of the stretchable wiring is constant in the central region and gradually decreases in the peripheral region toward the edge portion.

6. A stretchable device according to any one of claims 1 to 5, wherein, in a cross-sectional view, the edge of the stretchable wiring is symmetrical with respect to a center line that passes through the center of the stretchable wiring and is perpendicular to the thickness direction of the stretchable wiring.

7. The stretchable device according to any one of claims 1 to 6, wherein the stretchable wiring has a shape in plan view that has a short side direction and a long side direction, and wherein, in a cross-sectional view, each of the first principal surface and the second principal surface includes an inclined surface that is inclined such that the stretchable wiring tapers toward an edge that extends along the long side direction of the stretchable wiring.

8. The stretchable device according to claim 7, wherein, in a cross-sectional view, each of the first principal surface and the second principal surface further includes an inclined surface that is inclined so that the stretchable wiring tapers toward an edge extending along a short direction of the stretchable wiring.

9. The stretchable device according to any one of claims 1 to 8, wherein at least one of the first stretchable material layer and the second stretchable material layer has a raised portion along the thickness direction of the stretchable wiring.

10. A stretchable device according to any one of claims 1 to 9, wherein each of the first stretchable material layer and the second stretchable material layer has a portion that protrudes outward along the thickness direction of the stretchable wiring.

11. A stretchable device according to any one of claims 1 to 10, wherein, in a cross-sectional view, the first stretchable material layer and the second stretchable material layer gradually approach each other from the center side of the stretchable wiring toward the edge side.

12. The stretchable device according to any one of claims 1 to 11, wherein the first stretchable material layer and the second stretchable material layer are made of a thermoplastic resin.

13. The stretchable device of any one of claims 1 to 12, wherein the first elastic material layer and the second elastic material layer are made of the same material.

14. The stretchable device according to any one of claims 1 to 13, wherein the first stretchable material layer and the second stretchable material layer are directly bonded to each other around the periphery of the stretchable wiring.

15. A stretchable device according to any one of claims 1 to 14, wherein the first stretchable material layer and the second stretchable material layer are integrated with each other around the stretchable wiring.

16. A stretchable device according to any one of claims 1 to 15, wherein the stretchable wiring is surrounded by a stretchable member that branches into the first stretchable member layer and the second stretchable member layer.

17. A stretchable device according to any one of claims 1 to 16, wherein, when viewed in the thickness direction of the stretchable wiring, the stretchable wiring comprises a stretchable region and a non-stretchable region, and in the thickness direction of the stretchable wiring, the second stretchable material layer covers at least the stretchable region of the stretchable wiring.

18. The stretchable device according to claim 17, wherein the stretchable wiring in the stretchable region and the stretchable wiring in the non-stretchable region have mutually different cross-sectional shapes.

19. A stretchable device according to any one of claims 1 to 18, wherein, in a cross-sectional view, the width dimension of the second stretchable material layer in the width direction of the stretchable wiring is equal to or greater than the sum of the width dimension of the stretchable wiring and twice the thickness dimension of the second stretchable material layer.

20. The stretchable device according to any one of claims 1 to 19, wherein the thickness dimension of each of the first stretchable material layer and the second stretchable material layer is 10 μm or more.

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