Stretchable device and method for manufacturing same

Abstract

The present disclosure provides a stretchable device comprising a stretchable fabric, a stretchable substrate joined to the stretchable fabric, and a stretchable wiring disposed on the stretchable substrate, wherein the stretchable substrate contains a thermoplastic resin.

Description

Stretchable device and method for manufacturing the same

[0001] The present disclosure relates to a stretchable device and a method for manufacturing the stretchable device.

[0002] Conventionally, stretchable devices including stretchable substrates have been known (Patent Document 1). Stretchable devices can be used for, for example, living bodies or devices that require stretchability.

[0003] Japanese Patent Application No. 2017-118109, Japanese Patent Laid-Open No. 2016-088015

[0004] As a stretchable device applicable to wearable devices or the like, a fabric-based stretchable device attached to a fabric is required. Usually, an adhesive is used for bonding the fabric and the resin. Alternatively, for example, a thermoplastic resin composite in which a thermoplastic resin and a fabric are partially heat-sealed is known (Patent Document 2).

[0005] On the other hand, the present inventors have found the following problems when applying the above-described bonding structure to a stretchable device.

[0006] A fabric-based stretchable device is required to be stretchable during its use. However, when the stretchable substrate and the fabric are bonded using an adhesive, the presence of the adhesive layer located between the stretchable substrate and the fabric may reduce the stretchability of the entire stretchable device. Further, when partial heat-sealing is applied to a stretchable device, the stretchable substrate may peel off from the fabric due to the stress acting between the fabric and the stretchable substrate during elongation of the stretchable device. If the fusion range between the stretchable substrate and the fabric is expanded to improve the peel resistance, the stretchability of the stretchable device may be reduced.

[0007] The present disclosure has been made in view of the above problems. That is, the main object of the present disclosure is to provide a fabric-based stretchable device having excellent stretchability and a method for manufacturing the stretchable device.

[0008] As a result of intensive studies to solve the above problems, the present inventors have arrived at an invention of a stretchable device and a method for manufacturing the same in which the above main object is achieved.

[0009] An expandable device according to one embodiment of the present disclosure comprises an expandable fabric, an expandable substrate joined to the expandable fabric, and expandable wiring arranged on the expandable substrate, wherein the expandable substrate includes a thermoplastic resin.

[0010] Furthermore, a method for manufacturing a stretchable device according to one embodiment of the present disclosure includes forming stretchable wiring on a first main surface of a stretchable substrate containing a thermoplastic resin, overlapping a stretchable fabric with a second main surface of the stretchable substrate located on the opposite side of the first main surface, and directly joining the stretchable fabric and the stretchable substrate.

[0011] According to one embodiment of the present disclosure, a stretchable device based on a fabric with excellent elasticity, and a method for manufacturing the stretchable device are provided.

[0012] This is a schematic cross-sectional view showing a stretchable device according to the first embodiment of the present disclosure. This is a schematic enlarged cross-sectional view showing portion II in Figure 1. This is a schematic enlarged cross-sectional view showing portion III in Figure 1. This is a schematic enlarged cross-sectional view showing a stretchable device according to a modified example of the first embodiment of the present disclosure. This is a schematic cross-sectional view showing a stretchable device according to the second embodiment of the present disclosure. This is a schematic diagram for explaining a method for manufacturing a stretchable device according to one embodiment of the present disclosure.

[0013] The embodiments of this disclosure will be described in detail below. It should be noted that the applicant provides the following descriptions and examples to enable those skilled in the art to fully understand this disclosure, and is not intended to limit the subject matter described in the claims. In other words, this disclosure is not particularly limited to the preferred embodiments described below, and can be modified and implemented as appropriate within the scope of its purpose. For convenience, embodiments and examples may be presented separately to facilitate explanation or understanding of key points, but partial substitution and / or combination of configurations shown in different embodiments is possible. In descriptions of such embodiments, redundant explanations of substantially identical matters may be omitted, and only differences may be described. In particular, similar effects and benefits from similar configurations may not be mentioned sequentially in each embodiment.

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

[0015] In this specification, the terms "thickness direction of the stretchable device," "thickness direction of the stretchable substrate," and "lamination direction of the stretchable substrate" may be used interchangeably. Such directions correspond to direction Y in the figures.

[0016] In this specification, "cross-sectional view" or "cross-sectional shape" refers to the form of the stretchable device as viewed from a direction substantially perpendicular to the thickness direction Y (simply put, the form when the stretchable device is cut by a plane parallel to the thickness direction Y). Furthermore, in this specification, "plan view" refers to a sketch of the object as viewed from above or below along the thickness direction Y of the stretchable device.

[0017] Furthermore, in this specification, "above" an element includes not only cases where it is in contact with the upper surface of the element, but also cases where it is not in contact with the upper surface of the element. In other words, "above" an element includes not only positions above the element at a distance, i.e., positions above the element via other objects, or positions above it at a distance, but also positions directly above the element in contact with it. Moreover, "above" does not necessarily mean the upper side in the vertical direction. "Above" merely indicates the relative positional relationship of an element.

[0018] As used herein, “perpendicular” and “nearly perpendicular” do not necessarily mean perfectly perpendicular, but include configurations that are slightly off from it (for example, within ±10° from perfectly perpendicular, or within ±5°).

[0019] Furthermore, the term "approximately parallel" as used herein does not necessarily mean perfectly parallel, but includes configurations that are slightly deviated from perfect parallelism (for example, within a range of ±10° from perfect parallelism, or within a range of ±5°).

[0020] Hereinafter, a stretchable device according to one embodiment of this disclosure will be described with reference to the drawings. Although the description will refer to the drawings as necessary, the illustrations are provided only schematically and illustratively for the purpose of understanding this disclosure, and the appearance, dimensional ratios, etc., may differ from the actual device.

[0021] [Stretchable Device Configuration] The configuration of the stretchable device will be described with reference to Figure 1. Figure 1 is a schematic cross-sectional view illustrating a stretchable device 1 according to the first embodiment of this disclosure.

[0022] The stretchable device 1 comprises a stretchable fabric 10 and a stretchable circuit board 20 joined to the stretchable fabric 10. The stretchable circuit board 20 comprises a stretchable base material 220 and stretchable wiring 230 arranged on the main surface 222 of the stretchable base material 220. The stretchable fabric 10 and the stretchable circuit board 20 may be in close contact by the joining of the stretchable fabric 10 and the stretchable base material 220.

[0023] The stretchable device of this disclosure is characterized in that the stretchable fabric 10 and the stretchable circuit board 20 are joined without the use of an adhesive. The stretchable base material 220 of the stretchable circuit board 20 may be in direct contact with the stretchable fabric 10. In other words, the stretchable fabric 10 and the stretchable base material 220 may be joined without an adhesive. This avoids the reduction in the stretchability of the stretchable device caused by the presence of an adhesive, and thus a stretchable device with superior stretchability can be obtained.

[0024] [First Embodiment] The main components included in the stretchable device 1 of this disclosure will be described below with reference to Figure 1.

[0025] (Stretchable Fabric) The stretchable fabric 10 (hereinafter also simply referred to as "fabric") may be a sheet-like stretchable fabric. In this specification, "stretchability" simply means the property of being able to stretch and shrink, and can also be referred to as stretchability, stretchableness, 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 shrink when released from the stretched state. By using such a fabric, the stretchable fabric 10 becomes stretchable together with the stretchable base material 220. This makes it possible to obtain a stretchable device that is suitable in terms of stretchability. In addition, when the stretchable device 1 is stretched or compressed, the stretchable fabric 10 and the stretchable base material 220 can stretch and compress together, and the peel resistance of the stretchable fabric 10 and the stretchable base material 220 can be improved.

[0026] The material and structure of the stretchable fabric 10 are not particularly limited, as long as it is stretchable. For example, it can be any fiber structure including woven fabrics, knitted fabrics, nonwoven fabrics, and nets. Although this is merely an example, more specific examples of stretchable fabrics 10 include fabrics made of cotton, polyurethane, polyester, nylon, polytrimethylene terephthalate, polyethylene, acrylic, or combinations thereof. In particular, if the stretchability and heat resistance of the stretchable fabric are important, nylon, polyurethane, polytrimethylene terephthalate, or mixtures thereof are especially preferred.

[0027] (Stretchable base material) The stretchable base material 220 (hereinafter also simply referred to as "base material") may be made of a stretchable material having a sheet-like or film-like shape. The stretchable base material 220 contains a thermoplastic resin. The stretchable base material 220 may contain a thermoplastic resin at least in region A where the stretchable base material 220 and the stretchable fabric 10 to which the stretchable base material 220 is joined are joined. Preferably, the stretchable base material 220 is a thermoplastic resin. Although this is merely an example, the thermoplastic resin contained in the stretchable base material 220 may be at least one selected from the group consisting of, for example, olefin-based resin elastomers, styrene-based resin elastomers, urethane-based resin elastomers, and silicone-based resin elastomers.

[0028] Although only one stretchable substrate 220 is shown in Figure 1, the stretchable device 1 may include one or more additional stretchable substrates. For example, one or more additional stretchable substrates may be laminated on the stretchable substrate 220. When the stretchable device 1 includes multiple stretchable substrates 220, each of the multiple stretchable substrates 220 may be made of the same material, or they may be made of different materials.

[0029] The thickness of the stretchable substrate 220 is not particularly limited, but if the overall stretchability of the stretchable device is important, it is preferably 1 mm or less, and more preferably 300 μm or less. If the overall mechanical strength of the stretchable device is important, the thickness of the stretchable substrate is preferably 10 μm or more, or 40 μm or more. Furthermore, if the stretchable device 1 comprises multiple stretchable substrates 220, each of the multiple stretchable substrates may have the same thickness, or they may have different thicknesses.

[0030] (Stretchable Wiring) Stretchable wiring 230 (hereinafter also simply referred to as "wiring") is arranged on the stretchable substrate 220. The stretchable wiring 230 is made of a material that is stretchable and conductive. For example, the stretchable wiring 230 may be a mixture of conductive particles and resin.

[0031] As conductive particles, for example, at least one metal powder selected from the group consisting of Ag (silver), Cu (copper), and Ni (nickel) can be used. 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. The shape of the conductive particles is not particularly limited, but is preferably, for example, substantially spherical. Alternatively, from the viewpoint of improving elasticity, the shape of the conductive particles can be substantially elliptical, polyhedral, flattened, or an irregular shape such as a shape with protrusions.

[0032] The resin mixed with the conductive particles may be, for example, at least one resin selected from the group consisting of epoxy resins, urethane resins, acrylic resins, and silicone resins. Preferably, the resin is a thermoplastic resin. More preferably, the thermoplastic resin is at least one thermoplastic resin selected from the group consisting of, for example, thermoplastic acrylic resins and thermoplastic urethane resins.

[0033] Although only one stretchable wiring 230 is shown in Figure 1, one or more additional stretchable wirings may be provided. For example, multiple stretchable wirings may be provided on the same main surface of the stretchable substrate 220. Alternatively, the stretchable device 1 may comprise multiple stretchable substrates, with stretchable wiring provided on each of the multiple stretchable substrates. Each of the multiple stretchable wirings may be made of the same material, or they may be made of different materials.

[0034] The thickness of the stretchable wiring 230 is preferably 100 μm or less, and more preferably 50 μm or less. Furthermore, if the mechanical strength of the stretchable wiring 230 is important, the thickness of the stretchable wiring 230 is preferably 5 μm or more. When the stretchable device 1 comprises a plurality of stretchable wirings 230, each of the plurality of stretchable wirings 230 may have the same thickness, or they may have different thicknesses.

[0035] The stretchable wiring 230 may be extended in any direction. The stretchable wiring 230 may extend along the direction of extension of the main surface 222 of the stretchable base material 220 (the direction perpendicular to the Y direction in Figure 1). When viewed from the thickness direction Y of the stretchable base material 220, the stretchable wiring 230 does not necessarily have to be arranged in a straight line, but may be arranged in a curved shape, for example. Also, when viewed from the thickness direction Y, the stretchable wiring 230 does not necessarily have to extend in one direction, but may extend in various directions on the main surface 222 of the stretchable base material 220.

[0036] In the stretchable device 1 of this disclosure, the stretchable base material 220 is placed on the main surface 12 of the stretchable fabric 10. The stretchable fabric 10 and the stretchable base material 220 may be in close contact by joining the main surface 12 of the stretchable fabric 10 and the main surface 224 of the stretchable base material 220. In such joining, the main surface 12 of the stretchable fabric and the main surface 224 of the stretchable base material may be in direct contact. The main surface 224 of the stretchable base material that is joined to the stretchable fabric 10 can also be called the joining surface.

[0037] The stretchable wiring 230 may be arranged on a main surface 222 located on the opposite side of the joining surface 224 with the stretchable fabric 10. In such a structure, a stretchable base material 220 may be interposed between the stretchable fabric 10 and the stretchable wiring 230. Hereinafter, of the two opposing main surfaces 222 and 224 of the stretchable base material 220, the main surface located on the side where the stretchable wiring 230 is arranged will also be referred to as the first main surface 222, and the joining surface with the stretchable fabric 10 will also be referred to as the second main surface 224.

[0038] According to this disclosure, the stretchable fabric 10 and the stretchable base material 220 are joined without the use of an adhesive. In other words, there is no adhesive between the stretchable fabric 10 and the stretchable base material 220. This avoids the reduction in elasticity that occurs when an adhesive is included, and thus makes it possible to obtain a stretchable device with superior elasticity.

[0039] Furthermore, according to this disclosure, the adhesive layer between the stretchable fabric 10 and the stretchable base material 220 can be omitted, thereby reducing the overall thickness of the stretchable device. This makes it possible to obtain a stretchable device that is highly elastic and has a low profile.

[0040] Thus, the region A, which includes the main surface 12 of the stretchable fabric 10 and the second main surface 224 of the stretchable base material, is a region where the stretchable fabric 10 and the stretchable base material 220 are in direct contact and joined together, and can also be referred to as a contact boundary region, a direct joining region, an engagement region, etc. The stretchable device of this disclosure also features in the detailed structure of the contact boundary region A.

[0041] Figure 2 is a schematic enlarged view of part of the contact boundary region A, showing part II in Figure 1. As shown, the stretchable fabric 10 is a fibrous structure composed of multiple fibers 110, and therefore has fine irregularities on its surface. The stretchable base material 220 also has irregularities on its second main surface 224 and may be joined to interlock with the irregularities of the stretchable fabric 10. This structure can also be understood as a structure in which a part 223 of the stretchable base material 220 extends into the interior of the stretchable fabric 10 in a cross-sectional view. The part 223 of the stretchable base material 220 may be located between the multiple fibers 110 contained in the stretchable fabric 10. In other words, the part 223 of the stretchable base material 220 may be inserted into the gaps formed between the multiple fibers 110 constituting the stretchable fabric 10. Such gaps may be, for example, gaps such as a mesh formed by the multiple fibers 110 contained in the stretchable fabric 10. The stretchable base material 220 may have a structure in which a portion 223 of it fits into the gaps 17 between the multiple fibers 110 present on the main surface 12 of the stretchable fabric 10. In other words, although the stretchable fabric 10 and the stretchable base material 220 are joined at a macroscopic level, at a microscopic level, a portion 223 of the stretchable base material 220 may have a structure in which a portion 223 of it fits between the multiple fibers 110.

[0042] In this specification, "a part 223 of the stretchable base material enters into the stretchable fabric 10" includes a structure in which a part 223 of the stretchable base material extends so as to protrude into the stretchable fabric 10. In the thickness direction Y, when the direction from the stretchable fabric 10 side toward the stretchable wiring 230 side is defined as the +Y direction, and the direction opposite to the +Y direction, i.e., the direction from the stretchable wiring 230 side toward the stretchable fabric 10 side is defined as the -Y direction, it includes that a part 223 of the stretchable base material is located more on the -Y direction side than the portion of the main surface 12 of the stretchable fabric 10 closest to the stretchable wiring 230. Such a structure can also be paraphrased as that, in a cross-sectional view, the portion of the main surface 12 of the stretchable fabric 10 located most on the +Y direction side is arranged closer to the stretchable wiring 230 compared to the portion of the second main surface 224 of the stretchable base material 220 located most on the -Y direction side.

[0043] As shown in FIG. 2, by having a structure in which a part 223 of the stretchable base material enters between the fibers 110 of the stretchable fabric, the second main surface 224 of the stretchable base material may have a concavo-convex region 225 having a concavo-convex structure at the contact boundary region A (see FIG. 1) where it is joined to the stretchable fabric 10. The "concavo-convex region" in this specification refers to a region having a plurality of concave portions and convex portions in a cross-sectional view. The stretchable base material 220 may have a concavo-convex structure over the contact boundary region A. In such a structure, it can also be understood that the stretchable base material 220 includes a concavo-convex region 225 joined to the stretchable fabric 10 on the second main surface 224 of the stretchable base material 220. In other words, the stretchable base material 220 may be joined to the stretchable fabric 10 at the concavo-convex region 225. By the concavo-convex structure of such a stretchable base material 220 meshing with the concavo-convex of the main surface 12 of the stretchable fabric 10, the stretchable fabric 10 and the stretchable base material 220 may be mechanically joined.

[0044] In a cross-sectional view, the concavo-convex region 225 may be formed by the second main surface 224 of the stretchable base material including a plurality of meandering portions, curved portions, bent portions, or a combination thereof. The concavo-convex region 225 does not necessarily have a regular concavo-convex structure in a cross-sectional view, and may have an irregular concavo-convex shape in which meandering portions, curved portions, and / or bent portions are randomly combined.

[0045] In such a concavo-convex region 225, the stretchable base material 220 may penetrate into a predetermined depth within the stretchable fabric in a cross-sectional view. As shown in FIG. 2, it can also be understood that the stretchable base material 220 has an indented structure that penetrates from the main surface 12 of the stretchable fabric 10 along the thickness direction Y of the stretchable base material to a predetermined range. Therefore, such a concavo-convex region 225 can also be referred to as an "indentation region", "penetration region", "invasion region", "intrusion region" of the stretchable base material 220 into the stretchable fabric 10, or an "overlap region" between the stretchable fabric 10 and the stretchable base material 220, etc.

[0046] Thus, by having a structure in which a part of the stretchable base material 220 penetrates between a plurality of fibers 110 of the stretchable fabric, the stretchable base material 220 can be joined so as to be hooked to the stretchable fabric 10. That is, the stretchable fabric 10 and the stretchable base material 220 may be joined to each other by a fine hooking structure formed by a part of the stretchable base material 220 penetrating into the stretchable fabric 10, rather than by adhesion via an adhesive. The stretchable fabric 10 and the stretchable base material 220 may be joined by such a fine mechanical bond.

[0047] The present inventor has found that the stretchable fabric 10 and the stretchable base material 220 can be suitably joined without using an adhesive by such a fine mechanical bond. Surprisingly, the joining of the stretchable fabric 10 and the stretchable base material 220 by such a mechanical bond can not only improve the stretchability by not using an adhesive, but also improve the peel resistance. Specifically, an effect of improving the peel resistance between the stretchable fabric 10 and the stretchable base material 220 can be brought about.

[0048] Generally, the use of adhesives in joining components can improve joint strength and delamination resistance. Stretchable devices undergo repeated stretching and contraction during use, and particularly in the stretched state, significant stress can be placed on the joints of each component. Therefore, in stretchable devices, strong adhesion between components, especially those made of dissimilar materials, is particularly crucial to prevent delamination. In other words, compared to other devices that do not stretch (e.g., flexible devices), both stretchability and delamination resistance are important for stretchable devices. From this perspective, adhesives have traditionally been used to improve delamination resistance when joining dissimilar materials, such as fabrics and stretchable substrates.

[0049] On the other hand, it has been newly discovered that the stretchable device of this disclosure can have excellent peel resistance even without using adhesive. In one embodiment of the stretchable device of this disclosure, it is possible to improve peel resistance compared to the case in which adhesive is used by the fine mechanical bonding described above. In other words, according to this disclosure, a stretchable device with excellent stretchability and excellent peel resistance can be obtained.

[0050] The uneven region 225 may occupy most of the area where the stretchable fabric 10 and the stretchable base material 220 overlap when viewed from the thickness direction Y. The uneven region 225 may extend continuously across the area where the stretchable fabric 10 and the stretchable base material 220 overlap when viewed from the thickness direction Y, or it may be provided intermittently. For example, the uneven region 225 may occupy at least 50% or at least 80% of the area where the stretchable fabric 10 and the stretchable base material 220 overlap when viewed from the thickness direction Y. For example, the uneven region 225 may be formed over the entire area where the stretchable fabric 10 and the stretchable base material 220 overlap when viewed from the thickness direction Y. With such a structure, the stretchable fabric 10 and the stretchable base material 220 are suitably joined, and a stretchable device with excellent peel resistance between the stretchable fabric 10 and the stretchable base material 220 can be obtained.

[0051] As shown in Figure 2, a portion 223 of the stretchable base material 220 may penetrate into the interior of the stretchable fabric 10 so as to seep into the interior of the stretchable fabric 10. The portion 223 of the stretchable base material 220 may have an uneven structure that fills the gaps between the multiple fibers 110 located on the main surface 12 of the stretchable fabric 10. The second main surface 224 of the stretchable base material 220 may have a cross-sectional shape that includes curved or bent portions along the outer contours of the multiple fibers 110 located on the main surface 12 of the stretchable fabric 10.

[0052] A portion 223 of the stretchable base material may engage with the fibers 110 that constitute the stretchable fabric 10. The portion 223 of the stretchable base material may extend into the interior of the stretchable fabric 10 and have a shape that catches on the fibers 110 that constitute the stretchable fabric 10. For example, the second main surface 224 of the stretchable base material may have a cross-sectional shape that follows the shape of the outer contour of the fibers 110 so as to entangle with a portion of the fibers 110 of the stretchable fabric 10. This means that a portion of the stretchable base material 220 that extends into the stretchable fabric 10 may not only extend along the thickness direction Y of the stretchable base material 220, but may also extend within the stretchable fabric 10 in any direction along the direction of extension of the fibers 110 within the stretchable fabric 10 (for example, a direction intersecting the thickness direction Y).

[0053] Figure 3 is a schematic enlarged cross-sectional view showing the cross-sectional structure of part III of the stretchable device shown in Figure 1. As shown in Figure 3, the stretchable base material 220 may have a plurality of recesses 226 recessed toward the stretchable wiring 230 side. The plurality of fibers 110 constituting the stretchable fabric 10 may be located within the recesses 226. In cross-sectional view, the recesses 226 may have a shape that is recessed along the outer contour of the fibers 110. In other words, the stretchable base material 220 may include a plurality of recesses 226 recessed on the second main surface 224 so as to have a cross-sectional shape corresponding to the outer contour of the plurality of fibers 110. The stretchable base material 220 may be joined to the fibers 110 in the recesses. With such a structure, the stretchable fabric 10 and the stretchable base material 220 are joined so as to interlock nicely, and a stretchable device with better peel resistance can be obtained.

[0054] Furthermore, as shown in Figure 2, a small gap 30 may be formed between the stretchable fabric 10 and the stretchable base material 220. For example, a gap 30 may exist between at least a portion of the multiple fibers 110 constituting the stretchable fabric 10 and a recess 226 in the stretchable base material 220 facing the fiber 110. In other words, the fiber 110 and the recess 226 do not need to be completely joined throughout, and a gap 30 may be formed by separating them in some areas. Having such a minute gap 30 between the stretchable fabric 10 and the stretchable base material 220 can relieve the stress acting on the stretchable base material 220 as the stretchable device expands and contracts. As a result, rupture and peeling of the stretchable base material 220 as the stretchable device expands and contracts can be suitably suppressed, making it possible to suitably expand and contract the stretchable device while the stretchable fabric 10 and the stretchable base material 220 are joined together.

[0055] According to the above-described structure, when joining the stretchable fabric 10 and the stretchable base material 220, the anchoring effect provided by a portion of the stretchable base material 220 that has entered into the stretchable fabric 10 can be further enhanced. Therefore, the mechanical bond between the stretchable fabric 10 and the stretchable base material 220 becomes stronger, and the peel resistance between the stretchable fabric 10 and the stretchable base material 220 can be improved.

[0056] As described above, the stretchable base material 220 may have a portion that penetrates into the interior of the stretchable fabric 10, so that at least the region of the second main surface of the stretchable base material 220 that is joined to the stretchable fabric 10 has an uneven surface structure, which is an uneven region 225. On the other hand, as shown in Figure 3, the first main surface 222 of the stretchable base material 220 that faces the stretchable wiring 230 on the opposite side of the second main surface 224 may be a substantially flat surface without an uneven surface structure. That is, the stretchable base material 220 may have an uneven surface structure on the second main surface 224, while the first main surface 222 may be a uniform flat surface. In such a structure, the stretchable base material 220 and the stretchable wiring 230 may be joined to each other on a flat surface.

[0057] In this specification, "approximately flat" and "flat" are not necessarily limited to structures that are perfectly flat, and microscopic irregularities corresponding to the multiple fibers 110 constituting the stretchable fabric 10 are permissible when observed at a magnification that allows for the discrimination of these irregularities. Because the first main surface of the stretchable base material 220 is approximately flat, it becomes easier to form stretchable wiring 230 with a more uniform thickness on the stretchable base material 220. By making the thickness of the stretchable wiring 230 uniform, the stretch rate of the stretchable wiring can be made uniform throughout the entire stretchable wiring 230. This is particularly advantageous in that it can reduce the unevenness of stress that occurs when the stretchable wiring is stretched and suppress the breakage of the stretchable wiring.

[0058] Figure 4 is an enlarged cross-sectional view schematically showing portion IIIA, which corresponds to portion III in Figure 1, in a stretchable device according to a modified example of the first embodiment of the present disclosure. As shown, the first main surface 222, which is located in a position overlapping with the uneven structure on the second main surface 224 of the stretchable substrate 220 when viewed from the thickness direction Y of the stretchable substrate, may also have an uneven structure in cross-sectional view. Furthermore, the main surface 232 of the stretchable wiring 230, which faces the first main surface 222 of the stretchable substrate, may also have an uneven structure corresponding to the first main surface 222.

[0059] Specifically, the stretchable wiring 230 may have an uneven surface on its main surface 232 facing the stretchable base material 220. In other words, each of the stretchable base material 220 and the stretchable wiring 230 may have an uneven surface region on its main surface, and these uneven surfaces may be positioned to overlap each other when viewed from the thickness direction Y of the stretchable base material. For the sake of explanation, the uneven surface region 225 located on the second main surface 224 of the stretchable base material 220 may be referred to as the "base material uneven surface region," and the uneven surface region 235 located on the main surface 232 of the stretchable wiring 230 may be referred to as the "wiring uneven surface region."

[0060] As shown in Figure 4, the wiring uneven region 235 may be located on the main surface 232 of the stretchable wiring 230 that is joined to the stretchable base material 220. The first main surface 222 of the stretchable base material 220 that is joined to the stretchable wiring 230 may have an uneven surface that is complementary to the wiring uneven region 235. In cross-sectional view, the interface between the stretchable base material 220 and the stretchable wiring 230 may have an uneven structure. The first main surface 222 of the base material and the main surface 234 of the wiring may be joined to each other by the combination of complementary uneven surfaces. This combination of uneven surfaces allows an anchoring effect to act at the interface between the stretchable base material 220 and the stretchable wiring 230, making it possible to improve peel resistance.

[0061] Furthermore, as shown in the figure, it is more preferable that the uneven structures of the substrate uneven region 225 and the wiring uneven region 235 correspond to each other. Specifically, the recesses 226 of the stretchable substrate in the substrate uneven region 225 and the recesses 236 of the stretchable wiring in the wiring uneven region 235 may be located substantially coaxially in the thickness direction Y. In other words, when viewed from the thickness direction Y, the recesses 226 of the stretchable substrate in the substrate uneven region 225 and the recesses 236 of the stretchable wiring in the wiring uneven region 235 may be located so as to overlap each other.

[0062] In this specification, "approximately coaxial" and "coaxial" are not necessarily limited to configurations that are perfectly coaxial, but also include configurations that are slightly off-coaxial. For example, configurations that are off-coaxial by a range of ±100 μm, or for example, ±50 μm, in the direction of extension of the stretchable substrate when viewed in cross-section are included.

[0063] Furthermore, as described above, by structuring the structure such that the recesses 226 of the stretchable substrate in the substrate uneven region 225 and the recesses 236 of the stretchable wiring in the wiring uneven region 235 are located substantially coaxially in the thickness direction Y, the thickness of the stretchable substrate 220 can be made substantially uniform. This makes it possible to make the stretchability substantially uniform throughout the entire stretchable substrate 220. As a result, stress concentration caused by unevenness in stretchability is suppressed, and a stretchable device with excellent mechanical strength can be obtained.

[0064] Furthermore, as shown in Figure 4, the uneven structure in the wiring uneven region 235 may be smoother than the uneven structure in the substrate uneven region 225. Specifically, the average unevenness height in the wiring uneven region 235 may be smaller than the average unevenness height in the substrate uneven region 225. In this specification, "unevenness height" refers to the average value of the difference in height between any recess and two convex portions adjacent to that recess in a cross-sectional view. For example, in a photograph taken with a microscope to magnify the cross-section of a stretchable device 200 times, the unevenness height can be measured for any 10 recesses, and the average value can be taken as the "average unevenness height".

[0065] In stretchable devices, stress can be applied to components such as the stretchable wiring 230 during stretching and contraction. In particular, since the stretchable wiring 230 is an important component used for transmitting power and / or signals, it is especially desirable to suppress the occurrence of wire breakage. With the above-described structure, the stretchable wiring 230 has a relatively gentle uneven structure, which allows for a more favorable distribution of the stress that may be applied to the stretchable wiring 230 compared to the case where it has a steep uneven structure. As a result, wire breakage caused by stress on the stretchable wiring 230 can be effectively suppressed.

[0066] If the priority is on suppressing wire breakage, the average unevenness height in the wiring unevenness region 235 may be, for example, 80% or less, 50% or less, or 25% or less of the average unevenness height in the substrate unevenness region 225. Also, if the priority is on peel resistance at the joint interface between the stretchable substrate 220 and the stretchable wiring 230, the average unevenness height in the wiring unevenness region may be, for example, 10% or more, 20% or more, or 40% or more of the average unevenness height in the substrate unevenness region 225.

[0067] [Second Embodiment] Next, a stretchable device according to a second embodiment will be described. Figure 5 is a schematic enlarged cross-sectional view showing a stretchable device 1A according to a second embodiment of the present disclosure. The stretchable device 1A according to the second embodiment differs from the stretchable device 1 according to the first embodiment in that the stretchable circuit board 20 further comprises a protective layer 240 that covers the stretchable wiring 230.

[0068] The stretchable device 1A further includes a protective layer 240 that covers the stretchable wiring 230 located on the stretchable substrate 220. By providing the protective layer 240, the stretchable wiring 230 can be protected from external elements, thereby reducing the risk of deterioration and breakage of the stretchable wiring 230.

[0069] The protective layer 240 only needs to cover at least a portion of the stretchable wiring 230 disposed on the first main surface 222 of the stretchable substrate 220. Preferably, the protective layer 240 may cover the stretchable wiring 230 except for the connection portion between the stretchable wiring 230 and the electronic component. At least a portion of the stretchable wiring 230 may be surrounded by the stretchable substrate 220 and the protective layer 240. This allows the stretchable wiring 230 to be suitably protected.

[0070] The protective layer 240 only needs to be placed on the stretchable wiring 230. For example, the protective layer 240 may be placed only on and near the stretchable wiring 230. The protective layer 240 may be placed along the extending direction of the stretchable wiring 230. Alternatively, as shown in Figure 4, the protective layer 240 may be placed from the stretchable wiring 230 to the first main surface 222 of the stretchable substrate 220. In other words, the protective layer 240 may cover the stretchable wiring 230 and extend over the entire stretchable substrate 220, overlapping with the stretchable substrate 220 when viewed from the thickness direction Y.

[0071] For example, when multiple stretchable wirings 230 are arranged on a stretchable substrate 220, each of the multiple stretchable wirings 230 may be individually covered by multiple protective layers 240. Alternatively, the multiple stretchable wirings 230 may be integrally covered by a single protective layer 240.

[0072] The protective layer 240 may be made of an elastic resin material, and more preferably an elastic thermoplastic resin material. Although this is merely an example, the protective layer 240 preferably includes at least one selected from the group consisting of olefin-based resin elastomers, styrene-based resin elastomers, urethane-based resin elastomers, and silicone-based resin elastomers. If the stretchable device has multiple protective layers 240, each of the multiple protective layers 240 may be made of the same material, or they may be made of different materials. Furthermore, the protective layer 240 may be made of the same material as the stretchable substrate 220, or they may be made of different materials.

[0073] The thickness of the protective layer 240 is not particularly limited, but if the stretchability of the stretchable device is important, it is preferably 100 μm or less, and more preferably 70 μm or less. If the mechanical strength of the stretchable device is important, the thickness of the protective layer 240 may be 10 μm or more, and preferably 20 μm or more. Furthermore, if the stretchable device comprises multiple protective layers 240, each of the multiple protective layers 240 may have the same thickness, or they may have different thicknesses.

[0074] (Method for manufacturing a stretchable device) A method for manufacturing a stretchable device according to one embodiment of this disclosure will be described below.

[0075] The method for manufacturing a stretchable device according to this disclosure mainly includes a substrate manufacturing step for manufacturing a stretchable circuit board 20 and a bonding step for bonding the stretchable circuit board 20 and a stretchable fabric 10.

[0076] (Substrate Manufacturing Process) In the substrate manufacturing process, first, a stretchable substrate 220 is prepared. Then, stretchable wiring 230 is formed on the main surface of the stretchable substrate 220. Specifically, in the joining process with the stretchable fabric 10 described later, the stretchable wiring 230 is formed on the first main surface 222 of the stretchable substrate 220, which is located on the opposite side of the second main surface 224 that will be joined to the stretchable fabric 10.

[0077] The stretchable wiring 230 may be formed by applying a conductive paste (for example, a conductive paste containing a mixture of conductive particles and resin) to the first main surface 222 of the stretchable substrate using screen printing, inkjet printing, or the like. This will result in the desired circuit pattern.

[0078] After forming the circuit pattern of the stretchable wiring 230, the stretchable wiring 230 may be formed on the stretchable substrate 220 by drying and curing the printed conductive paste.

[0079] After the stretchable wiring 230 is formed, a protective layer 240 covering the stretchable wiring 230 is formed as needed. The protective layer 240 may be formed to cover at least a portion of the stretchable wiring 230 arranged on the stretchable substrate 220. In other words, the protective layer 240 may partially cover the stretchable wiring 230 so that a portion of the stretchable wiring 230 is exposed, such as at the connection point with an electronic component (not shown). The protective layer 240 may be formed by applying or printing a paste or ink-like material. Alternatively, the protective layer 240 may be formed by heat-pressing a film or sheet-like material onto the stretchable wiring 230.

[0080] Through the above process, a stretchable circuit board can be obtained that comprises a stretchable base material 220, stretchable wiring 230, and optionally a protective layer 240.

[0081] (Joining Process) Next, the stretchable fabric 10 and the stretchable circuit board 20 are joined. Before joining, the stretchable fabric 10 and the stretchable circuit board 20 are superimposed so that the second main surface 224 of the stretchable base material 220, which is located on the opposite side of the first main surface 222 of the stretchable base material 220, is in contact with the main surface 12 of the stretchable fabric 10 (see Figure 6). In other words, the stretchable base material 220 may be superimposed on the stretchable fabric 10 so that the main surface 224, on which the stretchable wiring 230 is not arranged, faces the stretchable fabric 10.

[0082] Subsequently, the stretchable fabric 10 and the stretchable circuit board 20 are joined together while they are superimposed. Specifically, the stretchable fabric 10 and the stretchable circuit board 20 are joined together while they are superimposed.

[0083] The joining can be carried out by heat welding or thermocompression bonding. In other words, the stretchable base material 220 containing a thermoplastic resin may be softened by heating alone, or by heating and pressurizing, and the stretchable base material 220 and the stretchable fabric 10 may be joined. Considering the working temperature, working efficiency, and the peel resistance of the resulting stretchable device, joining by thermocompression bonding is more preferable.

[0084] By going through the above steps, the stretchable fabric 10 and the stretchable circuit board 20 are joined together, and a stretchable device based on the fabric can be obtained.

[0085] According to the method of this disclosure, by including a thermoplastic resin in the stretchable base material 220, the stretchable base material 220 is softened during the joining process, allowing a portion of the stretchable base material 220 to penetrate into the interior of the stretchable fabric through the gaps 17 between the multiple fibers constituting the stretchable fabric. The stretchable base material 220 and the stretchable fabric 10 are mechanically joined by the portion of the stretchable base material 220 that has penetrated into the interior of the stretchable fabric 10. As a result, the stretchable fabric 10 and the stretchable base material 220 can be joined without the need for an adhesive. Consequently, a stretchable device that is more suitable in terms of stretchability can be obtained, which avoids the reduction in stretchability caused by adhesives.

[0086] Furthermore, the method of this disclosure makes it possible to suitably join the stretchable fabric 10 and the stretchable base material 220 without using an adhesive. As a result, the step of applying an adhesive to the stretchable fabric 10 is omitted, making it possible to manufacture stretchable devices with higher efficiency.

[0087] Furthermore, in stretchable devices, particularly during stretching, delamination may occur at the interfaces between components due to differences in the elastic modulus of each component included in the stretchable device. Therefore, when an adhesive is included between the stretchable fabric 10 and the stretchable base material 220, the difference between the elastic modulus of the adhesive and the elastic modulus of the other components must also be considered when designing the stretchable device. On the other hand, in the manufacturing method of the stretchable device of this disclosure, the stretchable fabric 10 and the stretchable base material 220 are joined without the use of an adhesive. Therefore, it is not necessary to consider the elastic modulus of the adhesive, and it may be possible to construct a stretchable device with a simpler design.

[0088] In one embodiment, thermoplastic resin may also be used for the stretchable wiring 230 and / or the protective layer. This allows the stretchable wiring 230 and the protective layer to deform in accordance with the deformation of the stretchable base material 220 when the stretchable base material 220 deforms to penetrate into the interior of the stretchable fabric 10 during the joining process. As a result, each component can deform while remaining in close contact with each other, and a stretchable device with superior peel resistance can be obtained.

[0089] Preferably, the thermoplastic resin used in the stretchable base material 220 and the thermoplastic resin used in the stretchable wiring 230 may be made of different materials. For example, it is preferable that the thermoplastic resin used in the stretchable base material 220 has a lower softening point than the thermoplastic resin used in the stretchable wiring 230. This makes it possible to reduce the effects of heat that may be applied to the stretchable wiring 230 when it is heated during the joining process between the stretchable fabric 10 and the stretchable circuit board 20.

[0090] In particular, since the stretchable wiring 230 may contain conductive particles to impart conductivity, it is more susceptible to thermal effects compared to the stretchable substrate 220. In some cases, heat may reduce the conductivity and / or mechanical strength of the stretchable wiring 230. By including a thermoplastic resin with a higher softening point than the stretchable substrate 220 in the stretchable wiring 230, it is possible to reduce the thermal effects on the stretchable wiring 230 during the bonding process.

[0091] The joining process is more preferably carried out at a temperature between the softening point of the stretchable base material 220 and the softening point of the stretchable wiring 230. Specifically, the temperature at which the joining process is carried out is more preferably above the softening point of the stretchable base material 220 and below the softening point of the stretchable wiring 230. By carrying out the joining process within this temperature range, it is possible to suitably join the stretchable fabric 10 and the stretchable base material 220 while reducing the thermal influence on the stretchable wiring 230.

[0092] The embodiments of this disclosure have been described above, but these are merely typical examples. Those skilled in the art will readily understand that this disclosure is not limited thereto, and various embodiments are conceivable without altering the essence of this disclosure.

[0093] For example, the stretchable device of this disclosure may further include electronic components connected to the stretchable wiring 230. Examples of electronic components mounted on the stretchable device include, but are not limited to, passive components such as capacitors, resistors, and inductors; active components such as amplifiers and rectifiers; and sensor components such as acceleration sensors and temperature sensors.

[0094] A stretchable device may include one or more electronic components. If a stretchable device includes multiple electronic components, there may be multiple identical electronic components, or there may be multiple electronic components of different types.

[0095] Electronic components may be mounted during the substrate manufacturing process. For example, after the formation of the stretchable wiring 230, the electronic components may be mounted so as to be electrically connected to the stretchable wiring 230, thereby manufacturing a stretchable circuit board 20 equipped with electronic components. Subsequently, a bonding process between the stretchable fabric 10 and the stretchable circuit board may be performed.

[0096] Alternatively, electronic components may be mounted after the bonding process. For example, in the substrate manufacturing process, the stretchable circuit board 20 may be manufactured with at least a portion of the stretchable wiring 230 exposed, and after the stretchable fabric 10 and the stretchable circuit board 20 are bonded, electronic components may be mounted so as to be electrically connected to the exposed stretchable wiring 230.

[0097] Furthermore, the above-described embodiment of the present disclosure includes the following preferred embodiments: <1> A stretchable device comprising a stretchable fabric, a stretchable substrate joined to the stretchable fabric, and stretchable wiring disposed on the stretchable substrate, wherein the stretchable substrate contains a thermoplastic resin. <2> The stretchable device according to <1>, wherein the stretchable substrate contains a thermoplastic resin at least in the contact boundary region between the stretchable substrate and the stretchable fabric. <3> The stretchable device according to <1> or <2>, wherein, in cross-sectional view, a part of the stretchable substrate is located inside the stretchable fabric. <4> The stretchable device according to any one of <1> to <3>, wherein the stretchable fabric comprises a plurality of fibers, and a part of the stretchable substrate is engaged with at least a portion of the fibers. <5> The stretchable device according to any one of <1> to <4>, wherein the stretchable fabric comprises a plurality of fibers, and a part of the stretchable substrate extends between the plurality of fibers. <6> The stretchable device according to any one of <1> to <5>, wherein the stretchable fabric comprises a plurality of fibers, and in cross-sectional view, the stretchable base material comprises a plurality of recesses facing each of the plurality of fibers in the contact boundary region between the stretchable base material and the stretchable fabric. <7> The stretchable device according to <6>, wherein the stretchable base material is joined to the fibers at the recesses. <8> The stretchable device according to <6> or <7>, wherein there is a gap between at least a portion of the plurality of recesses and the fibers. <9> The stretchable device according to any one of <1> to <8>, wherein in cross-sectional view, the stretchable base material includes a base material uneven region having an uneven structure in the contact boundary region between the stretchable base material and the stretchable fabric. <10> The stretchable device according to <9>, wherein the stretchable wiring has a wiring uneven region including an uneven structure on the main surface facing the stretchable substrate, and is positioned such that the substrate uneven region and the wiring uneven region overlap each other when viewed from the thickness direction of the stretchable substrate. <11> The stretchable device according to any one of <1> to <10>, wherein there is no adhesive between the stretchable fabric and the stretchable substrate. <12> The stretchable device according to any one of <1> to <11>, wherein the stretchable wiring includes conductive particles and a thermoplastic resin.<13> The stretchable device according to any one of <1> to <12>, further comprising a protective layer covering the stretchable wiring located on the stretchable substrate. <14> The stretchable device according to <13>, wherein the protective layer contains a thermoplastic resin. <15> A method for manufacturing a stretchable device, comprising: forming stretchable wiring on a first main surface of a stretchable substrate containing a thermoplastic resin; overlapping a stretchable fabric with a second main surface of the stretchable substrate located on the opposite side of the first main surface; and directly joining the stretchable fabric and the stretchable substrate. <16> The method for manufacturing the device according to <15>, wherein the joining includes heat-pressing the stretchable fabric and the stretchable substrate. <17> The method for manufacturing the device according to <16>, wherein the stretchable wiring contains a thermoplastic resin, and the softening point of the thermoplastic resin contained in the stretchable substrate is lower than the softening point of the thermoplastic resin contained in the stretchable wiring. <18> The manufacturing method according to <17>, wherein the temperature at which the heat-compression bonding is performed is higher than the softening point of the stretchable substrate and lower than the softening point of the stretchable wiring. <19> The manufacturing method according to any one of <15> to <18>, further comprising forming a protective layer covering the stretchable wiring between forming the stretchable wiring and joining the materials.

[0098] Furthermore, the effects described above are merely illustrative examples. Therefore, this disclosure is not limited to the matters described above, and additional effects may exist.

[0099] Examples related to this disclosure are described below.

[0100] (Preparation of stretchable device) A stretchable device was manufactured according to the method of this disclosure. A stretchable sheet material measuring 40 mm × 10 mm × 40 μm was used as the stretchable substrate. A circuit pattern of stretchable wiring was formed on the stretchable substrate using a conductive paste containing conductive particles, namely silver and resin. The circuit pattern was a linear pattern extending along the tensile direction in the tensile test described later. The circuit pattern was dried and cured to obtain a stretchable circuit board comprising the stretchable substrate and stretchable wiring.

[0101] The resulting stretchable circuit boards were layered so that the stretchable fabric and the stretchable base material were in contact. As the stretchable fabric, a stretchable cloth made of nylon and polyurethane measuring 50 mm x 20 mm x 0.5 mm was used.

[0102] Subsequently, the stretchable fabric and the stretchable circuit board were joined by thermocompression bonding to obtain a fabric-based stretchable device.

[0103] As a comparative example, a stretchable device was prepared by bonding a stretchable fabric and a stretchable circuit board using an adhesive. An acrylic adhesive was placed between the stretchable fabric and the stretchable substrate, and then the stretchable fabric and the stretchable substrate were joined by heat compression bonding. The stretchable device was then fabricated using the same materials as in the examples.

[0104] (Evaluation of stretchable devices) The stretchable devices in the examples and comparative examples were evaluated for elongation and peel resistance. The evaluation method was as follows.

[0105] • Evaluation of Elongation Rate The elongation rate was measured using a constant-speed tensile testing machine. The stretchable device was pulled along its longitudinal direction at a tensile speed of 30 mm / min. The elongation rate was calculated according to the following formula (I): Elongation Rate (%) = (L / L) ０ )×100 (I) (wherein, L ０ (L) is the length of the stretchable device in the tensile direction before applying a load (normal state), and (D) is the length of the stretchable device in the tensile direction after applying a load (extended state).

[0106] - Evaluation of delamination resistance: Delamination resistance was measured using a constant-speed elongation tensile testing machine. The stretchable device was stretched by pulling it along its longitudinal direction at a tensile speed of 30 mm / min. When the elongation rate, calculated according to formula (I), reached 200%, the presence or absence of delamination in the stretchable device was visually observed. If delamination occurred in the stretchable device before the elongation rate reached 200%, the elongation rate at the time of delamination was recorded.

[0107] Two stretchable devices were prepared for each of the examples and comparative examples, and each was evaluated. The average elongation rate and the presence or absence of delamination are shown in Table 1. Regarding the presence or absence of delamination, in each of the examples and comparative examples, if no delamination was observed in either of the two stretchable devices evaluated, it was evaluated as "no delamination." If delamination was observed in at least one of the two stretchable devices, it was evaluated as "present delamination."

[0108]

[0109] As shown in Table 1, the elongation rate of the stretchable device in the example was 1.6 times that of the stretchable device in the comparative example, indicating a significantly higher elongation rate for the stretchable device in the example. Therefore, it has been confirmed that this disclosure provides a stretchable device with excellent elasticity by eliminating the need for adhesive.

[0110] Furthermore, as shown in Table 1, in the comparative example stretchable device, delamination occurred at the interface between the adhesive and the stretchable substrate in both stretchable devices when the elongation rate reached 125%. On the other hand, in the example stretchable device without adhesive, no delamination was observed even when the elongation rate reached 200%. From the above, it has been shown that the stretchable device of this disclosure exhibits superior delamination resistance compared to stretchable devices using adhesive, even though no adhesive is used. Therefore, the stretchable device of this disclosure may be preferable in terms of delamination resistance as well as stretchability.

[0111] 1: Stretchable device 10: Stretchable fabric 110: Fiber 12: Main surface of stretchable fabric 20: Stretchable circuit board 220: Stretchable substrate 222: First main surface 223: Part of stretchable substrate 224: Second main surface 225: Substrate uneven region 226: Recess of stretchable substrate 230: Stretchable wiring 234: Main surface of stretchable wiring 235: Wiring uneven region 236: Recess of stretchable wiring 240: Protective layer

Claims

1. A stretchable device comprising a stretchable fabric, a stretchable base material joined to the stretchable fabric, and stretchable wiring arranged on the stretchable base material, wherein the stretchable base material contains a thermoplastic resin.

2. The stretchable device according to claim 1, wherein the stretchable substrate contains a thermoplastic resin at least in the contact boundary region between the stretchable substrate and the stretchable fabric.

3. The stretchable device according to claim 1 or 2, wherein, in a cross-sectional view, a portion of the stretchable base material is located inside the stretchable fabric.

4. The stretchable device according to any one of claims 1 to 3, wherein the stretchable fabric comprises a plurality of fibers, and a portion of the stretchable base material is engaged with at least a portion of the fibers.

5. The stretchable device according to any one of claims 1 to 4, wherein the stretchable fabric comprises a plurality of fibers, and a portion of the stretchable base material extends between the plurality of fibers.

6. The stretchable device according to any one of claims 1 to 5, wherein the stretchable fabric comprises a plurality of fibers, and in cross-sectional view, the stretchable base material comprises a plurality of recesses facing each of the plurality of fibers in the contact boundary region between the stretchable base material and the stretchable fabric.

7. The stretchable device according to claim 6, wherein the stretchable base material is joined to the fibers in the recess.

8. The stretchable device according to claim 6 or 7, wherein a gap is provided between at least a portion of the plurality of recesses and the fiber.

9. The stretchable device according to any one of claims 1 to 8, wherein, in a cross-sectional view, the stretchable substrate includes a substrate uneven region having an uneven structure in the contact boundary region between the stretchable substrate and the stretchable fabric.

10. The stretchable wiring has a wiring uneven region including an uneven structure on the main surface facing the stretchable substrate, and is positioned such that the substrate uneven region and the wiring uneven region overlap each other when viewed from the thickness direction of the stretchable substrate.

11. The stretchable device according to any one of claims 1 to 10, wherein there is no adhesive between the stretchable fabric and the stretchable base material.

12. The stretchable device according to any one of claims 1 to 11, wherein the stretchable wiring comprises conductive particles and a thermoplastic resin.

13. The stretchable device according to any one of claims 1 to 12, further comprising a protective layer covering the stretchable wiring located on the stretchable substrate.

14. The stretchable device according to claim 13, wherein the protective layer comprises a thermoplastic resin.

15. A method for manufacturing a stretchable device, comprising: forming stretchable wiring on a first main surface of a stretchable substrate containing a thermoplastic resin; overlapping a stretchable fabric with a second main surface of the stretchable substrate located on the opposite side of the first main surface; and directly joining the stretchable fabric and the stretchable substrate.

16. The manufacturing method according to claim 15, wherein the joining includes heat-pressing the stretchable fabric and the stretchable base material together.

17. The manufacturing method according to claim 16, wherein the stretchable wiring contains a thermoplastic resin, and the softening point of the thermoplastic resin contained in the stretchable substrate is lower than the softening point of the thermoplastic resin contained in the stretchable wiring.

18. The manufacturing method according to claim 17, wherein the temperature at which the heat-sealing is performed is higher than the softening point of the stretchable substrate and lower than the softening point of the stretchable wiring.

19. The manufacturing method according to any one of claims 15 to 18, further comprising forming a protective layer covering the stretchable wiring between forming the stretchable wiring and joining the parts.

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