stretchable devices

Abstract

Provided is an elastic device comprising a laminate obtained by laminating a plurality of elastic substrates, and elastic wiring disposed within the laminate. The elastic wiring comprises two main wiring surfaces facing each other in the lamination direction of the elastic substrates. In a cross-sectional view, at least one of the main wiring surfaces includes a first region and a second region. The first region is a region where a portion of said main wiring surface protrudes higher in the lamination direction than the second region.

Description

[Technical Field]

[0001] The present disclosure relates to stretchable devices. [Background technology]

[0002] Stretchable devices in which stretchable wiring is mounted on a stretchable substrate have been known for some time. These stretchable devices can be worn on the human body.

[0003] Patent Document 1 describes a stretchable device with a multilayer structure in which a plurality of stretchable substrates are laminated and stretchable wiring is arranged on the main surface of the stretchable substrate. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6823472 Summary of the Invention [Problem to be solved by the invention]

[0005] In the stretchable device of Patent Document 1, at least one stretchable wire is provided on each of two opposing main surfaces of a plurality of stretchable substrates. The plurality of stretchable substrates provided with stretchable wires are stacked and pressure-bonded together with an interlayer stretchable substrate so that at least a portion of the stretchable wires provided on each main surface are in contact with each other.

[0006] The inventors of the present application have realized that the stretchable devices described above have problems to be overcome, and have newly discovered the need to take measures to address these problems. Specifically, they have discovered the following problems.

[0007] In general, stretchable wiring applied to stretchable devices is required to have a small thickness in order to obtain excellent stretchability. In particular, in stretchable devices having the above-mentioned laminated structure, a low profile of the device is more required from the viewpoint of stretchability and wearing comfort, and therefore, it is desirable that the thickness of the stretchable wiring is small. However, in a stretchable wiring with a small thickness, stress generated as the stretchable device stretches is likely to cause damage such as cracks and breaks in the stretchable wiring, which may reduce the reliability of the stretchable device.

[0008] 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 that has more suitable reliability even when it has a layered structure. [Means for solving the problem]

[0009] In order to achieve the above object, in one embodiment of the present disclosure, A laminate formed by laminating a plurality of stretchable substrates and a stretchable wiring disposed inside the laminate, The elastic wiring has two wiring main surfaces that face each other in the stacking direction of the elastic base material, In a cross-sectional view, at least one of the wiring main surfaces includes a first region and a second region; The first region is a region where a part of the wiring main surface is raised in the stacking direction more than the second region. [Effects of the Invention]

[0010] According to an embodiment of the present disclosure, the stretchable device has more suitable reliability even when it has a layered structure. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a schematic plan view of a stretchable device according to a first embodiment of the present disclosure. [Figure 2]FIG. 2 is a cross-sectional view of the stretchable device shown in FIG. 1 taken along line AA. [Figure 3] FIG. 3 is a schematic cross-sectional view showing a stretchable device according to a modified example of the first embodiment of the present disclosure. [Figure 4A] FIG. 4A is a schematic plan view of a stretchable wiring according to various modified examples of the first embodiment of the present disclosure. [Figure 4B] FIG. 4B is a schematic plan view of a stretchable wiring according to various modified examples of the first embodiment of the present disclosure. [Figure 4C] FIG. 4C is a schematic plan view of a stretchable wiring according to various modified examples of the first embodiment of the present disclosure. [Figure 4D] FIG. 4D is a schematic plan view of a stretchable wiring according to various modified examples of the first embodiment of the present disclosure. [Figure 4E] FIG. 4E is a schematic plan view of a stretchable wiring according to various modified examples of the first embodiment of the present disclosure. [Figure 5] FIG. 5 is a schematic plan view of a stretchable device according to a second embodiment of the present disclosure. [Figure 6] FIG. 6 is a cross-sectional view of the stretchable device shown in FIG. 5 taken along line BB. [Figure 7] FIG. 7 is a schematic cross-sectional view for explaining a method for producing a stretchable device according to the present disclosure. [Figure 8] FIG. 8 is a schematic cross-sectional view for explaining a method for manufacturing a stretchable device according to the present disclosure. [Figure 9A] FIG. 9A is a schematic cross-sectional view of a stretchable device used as an example. [Figure 9B] FIG. 9B is a schematic cross-sectional view of a stretchable device used as a comparative example. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In each embodiment, differences from those previously described will be mainly described. In particular, similar effects resulting from similar configurations will not be mentioned in each embodiment. Among the components in the following embodiments, components not recited in independent claims will be described as optional components. Furthermore, the size and size ratios of components shown in the drawings are not necessarily strict. Furthermore, in each figure, substantially identical components are assigned the same reference numerals, and duplicated descriptions may be omitted or simplified.

[0013] As used herein, the term "cross-sectional view" or "cross-sectional shape" refers to the shape of the stretchable device as viewed from a direction substantially perpendicular to the thickness direction (in simple terms, the shape of the stretchable device cut along a plane parallel to the thickness direction). When the stretchable device has a layered structure comprising multiple stretchable substrates, the term "cross-sectional view" or "cross-sectional shape" refers to the shape of the stretchable device as viewed from a direction substantially perpendicular to the layering direction of the stretchable substrates (in simple terms, the shape of the stretchable device cut along a plane parallel to the layering direction). Furthermore, the term "planar view" as used herein refers to a sketch of the object as viewed from above or below along the thickness direction (or layering direction) of the stretchable device.

[0014] 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.

[0015] [First embodiment] The structure of the stretchable device will be described with reference to Figures 1 and 2. Figure 1 is a top view schematically showing a stretchable device 100 according to a first embodiment of the present disclosure. Figure 2 is an AA cross-sectional view of the stretchable device 100 of Figure 1. Note that the cross-sectional views in this specification are cross-sections parallel to the thickness direction X of the stretchable device 100. In other words, they are cross-sections perpendicular to the stretching direction of the stretchable wire 20. Even when making an actual comparison, this can be confirmed by the above cross-sectional view at any position of the stretchable wire 20 stretching in a certain direction.

[0016] In the stretchable device 100, a stretchable wiring 20 is routed on the main surface 11 of the stretchable substrate 10. The shape of the stretchable device 100 is not particularly limited. For clarity, FIG. 1 depicts only wiring extending in a specific direction, but the stretchable wiring 20 may extend in any direction on the main surface 11 of the stretchable substrate. When viewed from the thickness direction X of the stretchable substrate 10, the stretchable wiring 20 does not necessarily have to be arranged in a straight line, and may be arranged, for example, in a curved line. When viewed from the thickness direction X, the stretchable wiring does not necessarily have to extend in one direction. The number of stretchable wirings is also not particularly limited, and one or more wirings may be arranged.

[0017] The stretchable device 100 may mainly comprise a stretchable substrate 10 and a stretchable wiring 20 provided on the main surface of the stretchable substrate 10. In addition, an adhesive layer 30 that can be attached to an adherend and that contributes to the mounting of the stretchable device 100 may further be provided.

[0018] Furthermore, in this specification, the term "adherend" refers to the object to which the stretchable device is attached, and can also be referred to as an adhesive object, an attached object, an object to be mounted, etc. For example, the adherend can be a living body.

[0019] The arrangement of these components will be described below with reference to Figures 1 and 2. As shown in Figures 1 and 2, an elastic wiring 20 is provided on the main surface 11 of the elastic substrate, and an adhesive layer 30 is provided on the second main surface 12 side.

[0020] (Stretchable base material 10) The stretchable substrate 10 (hereinafter also referred to simply as "substrate") is a sheet-like or film-like stretchable substrate, and is made of, for example, a stretchable resin material. Here, stretchability in this specification simply means the property of being able to stretch and contract, and can also be referred to as stretchability or stretchable. 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. Examples of resin materials used as stretchable substrates include thermoplastic polyurethane.

[0021] In one embodiment of the present invention, the stretchable substrates 10 are stacked one on top of another in the thickness direction. More specifically, a plurality of stretchable substrates 10 may have a multilayer structure in which the main surfaces of the stretchable substrates 10 are stacked so as to face each other. In other words, a plurality of stretchable substrates 10 may be stacked in the thickness direction X of the stretchable substrate to form a laminate 50.

[0022] The multiple stretchable substrates 10 included in the laminate 50 may be made of the same material, or stretchable substrates 10 made of different materials may be laminated together. Furthermore, the stretchable substrate located in the outermost layer of the laminate 50 (for example, the stretchable substrate located most distally from the adhesive layer 30) also contributes to protecting the stretchable wiring 20 arranged inside the laminate 50, and can therefore also be considered as a laminate layer, cover layer, protective layer, coating layer, or the like.

[0023] The thickness of the stretchable substrate 10 is not particularly limited, but in order to avoid inhibiting the expansion and contraction of the surface of the adherend 200 when attached to an adherend such as a living body, it is preferably 1 mm or less, more preferably 100 μm or less, and even more preferably 50 μm or less. The thickness of the stretchable substrate is preferably 1 μm or more. The multiple stretchable substrates 10 included in the laminate 50 do not necessarily have to have the same thickness. In other words, the multiple stretchable substrates 10 may each have a different thickness; for example, only the outermost layers may have different thicknesses.

[0024] (Stretchable wiring 20) The stretchable wiring 20 (hereinafter also simply referred to as "wiring") contains conductive particles and 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 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 conductive particles are preferably spherical in shape.

[0025] In one embodiment, when the stretchable device has a multilayer structure including a laminate 50 formed by stacking a plurality of stretchable substrates 10, the stretchable wiring 20 may be disposed inside the laminate 50. More specifically, the stretchable wiring 20 is positioned on the main surface of the stretchable substrate 10, and the stretchable substrates 10 may be stacked on one another so that the stretchable wiring 20 is located inside the laminate 50. In other words, a plurality of stretchable substrates 10 may be stacked with the stretchable wiring 20 sandwiched between them. Such a structure can also be interpreted as a plurality of stretchable substrates 10 being stacked so that the stretchable wiring 20 disposed on the main surface of one of the stretchable substrates 10 is sandwiched between the other stretchable substrates 10. In other words, inside the laminate 50 formed by stacking a plurality of stretchable substrates 10, the stretchable wiring may be sandwiched between the stretchable substrates 10 stacked on one another.

[0026] (adhesive layer 30) The adhesive layer 30 has adhesiveness that allows the stretchable device 100 to be attached to an adherend. The adhesive layer 30 has a substrate-side main surface located on the stretchable substrate 10 side and an adherend-side main surface located on the adherend side. The substrate-side main surface is the main surface located on the interior side of the stretchable device 100, and the adherend-side main surface is located opposite the substrate-side main surface and can be understood as the main surface located on the exterior side of the stretchable device 100. The stretchable device 100 is mounted so as to be bonded to an adherend on the adherend-side main surface of the adhesive layer 30, and the adherend-side main surface can also be referred to as the attachment surface, sticking surface, mounting surface, or the like. It is preferable that the adhesive layer 30 has adhesiveness on both main surfaces. In other words, the adhesive layer 30 may have adhesiveness not only on the surface that is attached to the adherend, but also on the substrate-side main surface.

[0027] The adhesive layer can be attached to the adherend on the main surface opposite the stretchable substrate. When the adherend is a living body, any adhesive can be used for the adhesive layer 30, as long as it is mild to the skin, has sufficient pressure-sensitive adhesive properties, and can be easily peeled off from the skin after use. Although merely illustrative, examples of the adhesive layer 30 include synthetic rubber-based adhesives, acrylic-based adhesives, urethane-based adhesives, natural rubber-based adhesives, and / or silicone-based adhesives, with synthetic rubber-based adhesives being more preferred. Furthermore, from the standpoint of adaptability to the shape and movement of the living body surface, the adhesive layer 30 preferably has excellent stretchability and flexibility.

[0028] (Characteristic parts of the first embodiment) Based on the details of the main components of the stretchable device described above, the characteristic parts of the first embodiment will be described below. The stretchable wire 20 comprises a first wiring principal surface 21 and a second wiring principal surface 23, which are two wiring principal surfaces that face each other in the stacking direction X of the stretchable substrate 10. In this specification, the stacking direction X corresponds to the thickness direction of the stretchable substrate / stretchable wire. In the stretchable device of the present disclosure, the stretchable wire 20 comprises a first region 25 (hereinafter also referred to as a raised region) in which a portion of at least one of the two wiring principal surfaces is raised in the stacking direction X, and a second region 26 corresponding to the portion other than the first region 25. As shown in the figure, the first region 25 is a region in which a portion of the wiring principal surface is raised in the stacking direction X more than the second region 26.

[0029] In this specification, the term "first region (raised region)" refers to a region that protrudes in the stacking direction X at a different height compared to a region other than the first region 25 of the wiring principal surface (i.e., the second region 26) in a cross-sectional view. In other words, the stretchable wire 20 refers to a region that locally rises in the stacking direction X of the stretchable substrate 10 more than the second region 26. In other words, in a cross-sectional view, at least one of the wiring principal surfaces of the stretchable wire 20 is not a uniform plane, but comprises a raised region 25 where a part of the wiring principal surface rises in the stacking direction X. It should be noted that in this specification, "a part of the wiring principal surface" refers to a portion that is greater than 0% and not more than 60% of the surface area of ​​the wiring principal surface when viewed in the stacking direction.

[0030] On the other hand, the second region 26 refers to the portion of the wiring main surface other than the partially raised first region 25, and may also be referred to as a non-raised region, a main region of the wiring main surface, a base region, etc. Alternatively, the second region 26 may be understood as a region that is relatively recessed with respect to the raised first region 25, or a region with a relatively reduced thickness.

[0031] Due to the structure including the raised region 25 on the wiring principal surface, the stretchable wire 20 may have two regions with different thicknesses in a cross-sectional view. In this specification, the thickness direction coincides with the stacking direction. The thickness of the stretchable wire 20 can also be expressed as the distance between the first wiring principal surface 21 and the second wiring principal surface 23 of the stretchable wire 20. In a cross-sectional view, the thickness T1 of the stretchable wire in the first region 25 may be greater than the thickness T2 of the stretchable wire in the second region 26 (see FIG. 3 ). In other words, the stretchable wire 20 may have a thickness in the second region 26 that is smaller than that of the first region 25. Therefore, it can also be understood that the region in which the stretchable wire 20 is relatively thick in a cross-sectional view is the first region 25, and the other region that is relatively thin is the second region 26. Therefore, the first region 25 can also be referred to as a thick region, and the second region 26 can also be referred to as a thin region, etc.

[0032] In the main wiring surface, the first region 25 and the second region 26 may be continuous with each other. In other words, the main wiring surface may be formed by a stepped surface spanning the first region 25 and the second region 26. In such a structure, the first region 25 and the second region 26 may also be considered to be adjacent to each other. For example, as shown in FIG. 2 , the main wiring surface may be formed by the second region 26, which is a plane extending approximately perpendicular to the stacking direction X, and the first region 25, which is continuous with the second region 26 and protrudes in the stacking direction X relative to the second region 26.

[0033] According to the stretchable device of the present disclosure, the strength of the stretchable wiring 20 can be improved by partially increasing the thickness of the stretchable wiring 20 by the raised region 25. This can suitably suppress the occurrence and / or extension of cracks in the stretchable wiring 20, and as a result, can suitably prevent breakage of the wiring 20. Therefore, the present disclosure can provide a highly reliable stretchable device that can more suitably prevent damage to the stretchable wiring 20 when the stretchable device is in use.

[0034] Furthermore, the inventors of the present application have discovered that a structure including the above-described raised region is suitable for optimally achieving both the stretchability of a stretchable device and the prevention of wire breakage. Generally, increasing the thickness of the wire is conceivable as a way to prevent wire breakage in a stretchable wire, but increasing the thickness of the wire can be a factor in reducing the comfort of wearing and / or the stretchability of the stretchable device. According to the present disclosure, the thickness of the stretchable wire 20 is increased locally in the raised region 25 without increasing the overall thickness, thereby making it possible to reduce the reduction in the comfort of wearing and / or the stretchability of the stretchable device. Therefore, the stretchable device of the present disclosure can achieve suitable stretchability for the stretchable device while suppressing wire breakage.

[0035] Furthermore, in a stretchable device having a laminated structure, the adhesion between the stretchable substrate and the stretchable wiring joined by pressure bonding may be relatively weak, and therefore, when stretching the stretchable device, there is a risk of delamination occurring between the stretchable substrate and the stretchable wiring joined by pressure bonding.

[0036] According to the present disclosure, by providing the stretchable wiring 20 with the raised region 25 as described above, the contact area between the stretchable substrate 10 and the stretchable wiring 20 increases compared to when the stretchable wiring 20 has a uniform surface (for example, a smooth, flat surface or a curved surface). As a result, the stretchable substrate 10 and the stretchable wiring 20 can be bonded over a larger area, and it may be possible to suitably suppress the occurrence of peeling (so-called delamination) between the substrate 10 and the wiring 20 that are tightly bonded and laminated to each other.

[0037] Furthermore, due to the difference in thickness between the first region 25 and the second region 26, an anchor effect can act in the bonding between the stretchable wiring 20 and the stretchable substrate 10. This anchor effect allows the wiring 20 and the substrate 10 to adhere more favorably. Therefore, the peel resistance between the wiring 20 and the substrate 10 is further improved, and a stretchable device that is more favorable in terms of reliability can be obtained.

[0038] Preferably, the stretchable wire 20 and the stretchable substrate 10 in contact with the stretchable wire 20 are bonded over the entire main wiring surface. That is, the stretchable wire 20 may be bonded to the stretchable substrate 10 in both the first region 25 and the second region 26. More specifically, it is preferable that the stretchable wire 20 and the stretchable substrate 10 are in close contact with each other on both the raised surface 25a of the first region, where part of the main wiring surface is raised, and the surface 26a of the second region. This makes it possible to more suitably increase the bonding area between the stretchable substrate 10 and the stretchable wire 20 and to obtain the effect of improving adhesion due to the anchor effect.

[0039] As described above, the stretchable wiring 20 of the stretchable device 100 of the present disclosure may be able to improve the strength of the wiring 20 while favorably maintaining stretchability. For this reason, the structure of the stretchable wiring 20 described in this specification may be favorably adopted not only for a stretchable wiring 20 present inside a laminate 50, such as one in which both main surfaces (21, 23) of the wiring 20 are covered with the stretchable substrate 10, but also for a stretchable wiring 20 provided on the outermost surface 50a of a laminate, in which one of the main wiring surfaces does not face the stretchable substrate 10 (see FIG. 8 ). Similarly, even in a stretchable device with a single-layer structure, by adopting the structure of the stretchable wiring of the present disclosure, a stretchable device that is more favorable in terms of strength and stretchability may be provided.

[0040] As described above, by raising a portion of the wiring main surface, the first region 25, which is the raised region, and the second region 26, which is the other region, may extend at different heights in the stacking direction X in a cross-sectional view. As a result, a step structure may be provided on the wiring main surface by the first region 25 and the second region 26. More specifically, the raised surface of the first region 25 may be located at a different height from the surface of the second region 26 in the stacking direction X, thereby providing a step structure by the first region 25 and the second region 26.

[0041] By joining the stretchable substrate 10 and the stretchable wiring 20 with such a step structure, the stretchable wiring 20 can be engaged by biting into the stretchable substrate 10. By biting into the stretchable substrate 10 in such a way, the anchor effect can be more suitably exerted in the joining of the stretchable substrate 10 and the stretchable wiring 20, and therefore the peel resistance between the substrate 10 and the wiring 20 can be improved.

[0042] In a cross-sectional view, the thickness T1 of the stretchable wiring in the first region may be, for example, 105% or more of the thickness T2 of the stretchable wiring in the second region, preferably 110% or more, and more preferably 125% or more (see FIG. 6). Furthermore, when emphasis is placed on the stretchability of the stretchable wiring 20, the thickness T1 of the stretchable wiring in the first region may be, for example, 200% or less of the thickness T2 of the stretchable wiring in the second region, preferably 180% or less, and more preferably 150% or less. If the difference in thickness of the stretchable wiring 20 in the first region 25 and the second region 26 is within the above-mentioned range, a stretchable device that is more suitable in terms of reliability and stretchability can be provided.

[0043] Specifically, in a cross-sectional view, the thickness T1 of the stretchable wiring in the first region may be, for example, 1 μm or more larger than the thickness T2 of the stretchable wiring in the second region, preferably 4.5 μm or more larger, and more preferably 5 μm or more larger. Furthermore, when emphasis is placed on the stretchability of the stretchable wiring 20, the difference in thickness between the thickness T1 of the stretchable wiring in the first region and the thickness T2 of the stretchable wiring in the second region may be, for example, 20 μm or less, and preferably 10 μm or less. If the difference in thickness of the stretchable wiring 20 in the first region 25 and the second region 26 is within the above-mentioned range, a stretchable device that is more suitable in terms of reliability and stretchability can be provided.

[0044] Furthermore, as will be described later, when a plurality of stretchable wires 20 are provided inside the laminate 50 and have at least partial overlapping portions when viewed from the stacking direction X, the plurality of stretchable wires 20 may be insulated from one another by disposing a stretchable substrate 10 between the wires 20. In other words, the stretchable substrate 10 interposed between the plurality of stretchable wires 20 may function as an insulator. In this case, by ensuring a sufficient thickness of the stretchable substrate 10, damage to the stretchable substrate 10 and the resulting dielectric breakdown can be more suitably suppressed even in a state in which the thickness of the stretchable substrate 10 is relatively reduced as the stretchable device is elongated. This makes it possible to provide a stretchable device that is more suitable in terms of connection reliability and durability.

[0045] In a cross-sectional view, the thickness T3 of the stretchable substrate facing the first region 25 is not particularly limited, as long as the stretchable substrate 10 can ensure interlayer insulation. In other words, the thickness T3 of the stretchable substrate is not particularly limited, as long as contact between conductive members such as the stretchable wiring 20 and electrodes (not shown) stacked via the stretchable substrate 10 is prevented and they are insulated from each other. For example, since the thickness of the stretchable substrate 10 can be reduced when stretched, if emphasis is placed on ensuring insulation when the stretchable device is stretched, the thickness T3 of the stretchable substrate may be 5 μm or more. On the other hand, if the thickness T3 of the stretchable substrate located between the wirings is too large, the stretchable device may be inferior in terms of stretchability and adhesion to an adherend. If emphasis is placed on the stretchability of the stretchable device and adhesion to an adherend, the thickness T3 of the stretchable substrate facing the first region 25 may be, for example, 500 μm or less.

[0046] In a preferred embodiment, in a cross-sectional view, the thickness T3 of the stretchable substrate facing the wiring principal surface having the raised region 25 is greater than the thickness T2 of the stretchable wire in the raised region 25. In other words, the thickness T2 of the stretchable wire in the raised region 25 is preferably smaller than the thickness T3 of the stretchable substrate adjacent to the wiring principal surface having the raised region 25. The portion of the stretchable substrate 10 facing the first region 25, which is a raised region, is more susceptible to stress from the stretchable wire 20 than the portion facing the non-raised second region 26. Therefore, in some cases, there is a risk that the stretchable substrate 10 may be more susceptible to tearing when the stretchable device is repeatedly stretched. Therefore, by ensuring a sufficient thickness of the stretchable substrate 10, the stress that the stretchable wire 20 in the raised region 25 may exert on the stretchable substrate 10 can be suitably alleviated. This may more suitably prevent damage to the stretchable substrate 10.

[0047] In a cross-sectional view, the thickness T3 of the stretchable substrate facing the first region 25 may be, for example, 110% or more, or 115% or more, and preferably 120% or more, of the thickness T2 of the stretchable wiring in the first region 25. On the other hand, if the thickness T3 of the stretchable substrate is too large, the stretchable device may be inferior in terms of stretchability and adhesion to an adherend. When prioritizing the stretchability and adhesion to an adherend of the stretchable device, the thickness T3 of the stretchable substrate facing the first region 25 may be, for example, 200% or less, or 180% or less, and preferably 150% or less, of the thickness T2 of the stretchable wiring in the first region 25. When the difference in thickness between the stretchable substrate 10 and the stretchable wiring 20 in the first region 25 is within the above-mentioned range, a stretchable device that is more suitable in terms of reliability and stretchability can be provided.

[0048] Dimensions such as the thickness of the stretchable substrate 10 and the first region 25 and second region 26 of the stretchable wiring 20 are measured by cutting the stretchable device along the thickness direction and analyzing the cross section. For example, measurements can be made using a three-dimensional measuring machine (e.g., Mitutoyo's QV series) or a microscope (e.g., Keyence's VHX series).

[0049] The stretchable wiring 20 may include a plurality of first regions 25. More specifically, two or more first regions 25 may be provided on one of the wiring main surfaces. Additionally or alternatively, as described below, at least one first region 25 may be provided on each of two wiring main surfaces that face each other in the stacking direction X. The plurality of first regions 25 do not necessarily have to protrude at the same height in a cross-sectional view, and may protrude at different heights from each other. Furthermore, their cross-sectional shapes may also be different from each other. When a plurality of first regions are provided and each has a different thickness, the thickness T1 of the thickest part is taken as the thickness of the first region.

[0050] 4A to 4E are plan views showing various modified examples of the stretchable wiring 20 included in the stretchable device of the first embodiment. As shown in the drawings, the raised region 25 may be formed at any position on the main wiring surface of the stretchable wiring 20 that faces the main surface 11 of the stretchable substrate. For example, the raised region 25 may be arranged so as to extend in the center of the stretchable wiring 20 (FIG. 4A). In such a structure, in a cross-sectional view, the main wiring surface may have a structure that includes a first region 25 and two second regions 26 on both sides of the first region 25.

[0051] In a preferred embodiment, when viewed from the stacking direction X of the stretchable substrate 10, the raised region 25 is located on the periphery of the stretchable wire 20 (FIGS. 4B to 4E). For example, the raised region 25 may extend so as to be located at least on the periphery of the stretchable wire 20. In other words, the wiring principal surface may have a region in which a portion including at least the periphery is raised. In one embodiment, when the stretchable wire 20 has a wiring side surface (or wiring end surface) that connects between the first wiring principal surface 21 and the second wiring principal surface 23, the raised region 25 may be provided so as to straddle the wiring side surface. In other words, the raised region 25 may be formed so as to be continuous with the wiring side surface.

[0052] In this specification, the "periphery of the stretchable wire" refers to the outer edge or contour portion of the stretchable wire 20 when viewed from the stacking direction X of the stretchable substrate. Delamination between the stretchable wire 20 and the stretchable substrate 10 and / or cracks in the stretchable wire 20 are likely to occur at the periphery of the stretchable wire 20. Therefore, by providing a raised region 25 at this periphery and partially increasing the thickness of the stretchable wire 20, it is possible to provide a stretchable device in which the occurrence of disconnection and delamination is suitably suppressed and which has higher reliability.

[0053] Furthermore, it is more preferable that the raised region 25 is provided so as to be located at least at a corner of the stretchable wire 20 ( FIG. 4B ). A corner refers to, for example, a portion where at least two sides that define the outline of the stretchable wire 20 are connected, and also includes a corner that is curved (for example, arc-shaped). Such a corner is particularly likely to concentrate stress in the stretchable wire 20, and is likely to become a starting point for breakage and delamination of the stretchable wire 20. Therefore, by providing a raised region 25 at the corner of the stretchable wire 20, it may be possible to more suitably suppress the occurrence of breakage and delamination of the stretchable wire 20.

[0054] In another modified example, the raised region 25 may extend along the periphery of the stretchable wire 20. Furthermore, the stretchable wire 20 may be provided with a plurality of raised regions 25 on one of the wiring principal surfaces. For example, when viewed from the stacking direction X, the stretchable wire 20 may be provided with two raised regions 25 extending along the periphery in the longitudinal direction of the stretchable wire 20 (FIG. 4C). Alternatively, when viewed from the stacking direction, the raised region 25 may extend along the periphery of the stretchable wire 20 so as to surround the wiring principal surface of the stretchable wire 20 in a frame shape (FIGS. 4D and 4E). In other words, when viewed from the stacking direction X, the stretchable wire 20 may be provided with a raised region 25 formed in a frame shape along the outline of the stretchable wire 20. Specifically, the stretchable wire 20 may be provided with a first region 25 (i.e., a raised region) extending along the periphery of the stretchable wire 20, and a second region 26 surrounded by the first region 25. In such a structure, the stretchable wiring 20 may have a structure that is thick at the periphery and thin at the center, thereby making it possible to realize a more reliable stretchable device that can suppress breakage and / or delamination.

[0055] The raised regions 25 may be formed intermittently as shown in FIG. 4D, or may be formed continuously as shown in FIG. 4E.

[0056] When the raised region 25 is located on the periphery of the stretchable wire 20 as shown in Figures 4C to 4E, the width dimension Wb of the raised region 25 in cross-sectional view is, for example, greater than 0% of the width dimension Wa of the stretchable wire, and preferably 10% or more (see Figure 4E). Furthermore, when emphasis is placed on the stretchability of the stretchable wire, the width dimension Wb of the raised region 25 may be, for example, 30% or less of the width dimension Wa of the stretchable wire, and preferably 25% or less. When the width dimension of the raised region 25 is in the above-mentioned range, a more reliable stretchable device can be provided that can suitably suppress breakage of the stretchable device. When multiple raised regions 25 are provided in cross-sectional view, the raised regions 25 may have different width dimensions from each other.

[0057] (Modification of the first embodiment) Next, a description will be given of a stretchable device 101 according to a modified example of the first embodiment. The stretchable device 101 differs from the stretchable device 100 according to the first embodiment in that the stretchable wiring 20 has raised regions 25 on each of two opposing wiring main surfaces (21, 23).

[0058] 3 is a schematic cross-sectional view of a stretchable device according to a modified example of the first embodiment. As shown in the figure, the stretchable wire 20 may have a raised region 25 on each of a first wiring principal surface 21 and a second wiring principal surface 23 that face each other in the stacking direction X. More specifically, the stretchable wire 20 has at least two raised regions 25, one raised region 25 being located on the first wiring principal surface 21 and the other raised region 25 being located on the second wiring principal surface 23. The multiple raised regions 25 arranged on these different wiring principal surfaces may rise in different directions along the stacking direction X of the stretchable substrate 10. According to this structure, the raised region 25 can also be interpreted as rising toward the stretchable substrate 10 that faces the wiring principal surface on which the raised region 25 is located. For example, as shown in FIG. 3, the raised region 25 located on the first wiring main surface 21 may be raised upward along the stacking direction X, while the raised region 25 located on the second wiring main surface 23 may be raised downward along the stacking direction X.

[0059] According to this structure, two stretchable substrates 10 adjacent to each other in the stacking direction X with the stretchable wire 20 sandwiched between them can be bonded to their respective wiring main surfaces that include the raised region 25. This makes it possible to increase the bonding area with the stretchable substrate 10 on both of the two wiring main surfaces (21, 23). Furthermore, because an anchor effect can be exerted on the bonding with the stretchable substrate 10 on both of the two wiring main surfaces (21, 23), the adhesion between the stretchable wire 20 and the stretchable substrate 10 that is stacked with the stretchable wire 20 sandwiched between them can be further improved.

[0060] Furthermore, as described above, in a structure having a raised region 25 on each of two opposing wiring principal surfaces (21, 23), the raised region 25 located on each wiring principal surface may be positioned coaxially along the stacking direction X. That is, the raised region 25 that rises on the first wiring principal surface 21 and the raised region 25 that rises on the second wiring principal surface 23 are preferably positioned coaxially along the stacking direction X of the stretchable substrate. In other words, when viewed from the stacking direction X, the raised region 25 that rises on the first wiring principal surface 21 and the raised region 25 that rises on the second wiring principal surface 23 preferably overlap each other. By using a structure such as the one described above, breakage of the stretchable wiring can be further suppressed,

[0061] In a preferred embodiment, the raised region 25 is provided on each of the first wiring principal surface 21 and the second wiring principal surface 23 along the periphery of the stretchable wire 20. That is, in a cross-sectional view, the stretchable wire 20 may be provided with the raised region 25 on each of the first wiring principal surface 21 and the second wiring principal surface 23 at both end sides in the width direction. According to this structure, in a cross-sectional view, the stretchable wire 20 has a shape in which the thickness of both end portions of the stretchable wire 20 is greater than the thickness of the central portion (a shape including a so-called approximate dogbone shape).

[0062] This locally increases the thickness of the stretchable wire 20 at the locations where the two raised regions 25 are located, which may make it possible to further improve the strength of the stretchable wire 20. This may make it possible to more effectively prevent cracks from extending and breakage of the stretchable wire 20. Furthermore, by providing raised regions 25 on both main surfaces of the stretchable wire 20, the peripheral portions that are likely to become the starting points of peeling can be suitably bonded to the stretchable substrate 10. Therefore, the above-described structure may be suitable not only for suppressing crack extension and breakage, but also for suppressing delamination.

[0063] As described above, in the wiring principal surface including the raised region 25, the base region 26, which is the region other than the raised region 25, does not necessarily have to be flat. For example, the base region 26 may be a curved surface. In such a structure, the raised region 25 may be formed by a portion of the wiring principal surface including the curved base region 26 being raised in the stacking direction X from the base region 26. Even in such a structure, the raised region 25 exerts an anchor effect, and the effect of improving adhesion between the wiring principal surface and the stretchable substrate 10 bonded to the wiring principal surface can be achieved.

[0064] (Second embodiment) Next, a description will be given of a stretchable device according to a second embodiment. The stretchable device differs from the stretchable device 100 according to the first embodiment in that the laminate 50 includes a plurality of stretchable wires therein.

[0065] FIG. 5 is a schematic plan view of a stretchable device 102 according to a second embodiment. FIG. 6 shows a cross-sectional view of the stretchable device 102 shown in FIG. 5 along line BB. As shown in the figure, the stretchable device may include a plurality of stretchable wires 20. The plurality of stretchable wires 20 are arranged so as to be sandwiched between a plurality of stretchable substrates 10 arranged in the stacking direction X, and may extend at different heights from each other as viewed from the stacking direction X. This structure can also be interpreted as a layered structure formed by stacking two or more layers of stretchable substrates 10, each layer including at least one stretchable wire 20 arranged on the main surface 11. In one embodiment, the plurality of stretchable wires 20 may have portions where at least a portion of them overlap each other via the stretchable substrate 10 as viewed from the stacking direction X. In other words, it is preferable that the stretchable substrate 10 is interposed in the portions where the plurality of stretchable wires 20 overlap as viewed from the stacking direction X. With this structure, the multiple stretchable wires 20 that overlap each other when viewed from the stacking direction X may be kept out of contact with each other due to the presence of the stretchable substrate 10 therebetween.

[0066] 5, the multiple stretchable wires 20 may overlap at the portions where they intersect with each other when viewed from the stacking direction X. Alternatively, the multiple stretchable wires 20 may extend approximately parallel to each other while overlapping with each other when viewed from the stacking direction X.

[0067] In general, the stretchable wire 20 has a higher hardness than the stretchable substrate 10. The inventors of the present application have found that when multiple stretchable wires 20 have portions where they contact each other in the stacking direction X between two adjacent stretchable substrates 10, the contact portions between the wires become locally hard, generating a stress distribution that may make the wires 20 more susceptible to breakage. That is, when multiple stretchable wires 20 are stacked so that they contact each other, stress tends to concentrate at the contact portions between the stretchable wires 20, making the wires 20 more susceptible to damage. Furthermore, because the contact portions between the stretchable wires 20 are harder than non-contact portions, the elongation rate of the stretchable device as a whole may decrease. In other words, direct contact between wires may also affect the stretchability of the stretchable device. As described above, in the stretchable device of the present disclosure, the stretchable wires 20 are indirectly overlapped via the stretchable substrate 10. This makes it possible to suitably alleviate localized variations in hardness, and to provide a stretchable device that is more suitably resistant to breakage and more suitably stretchable.

[0068] In one embodiment, multiple stretchable wires 20 present between different layers may be conductively connected to each other via vias (not shown). For example, in a cross-sectional view, stretchable wires 20 located at different heights in the stacking direction X may be in non-contact with each other via the stretchable substrate 10, but may be electrically connected by vias formed in the stretchable substrate 10. Alternatively, wires and components (for example, electronic components such as electrodes or sensors) located between different layers may be conductively connected to each other via vias.

[0069] Furthermore, multiple stretchable wires 20 may be arranged between two adjacent stretchable substrates 10, as long as there are no direct contact portions between the stretchable wires 20 in the stacking direction X. In other words, when viewed from the stacking direction X, multiple stretchable wires located between the same layers of two adjacently arranged stretchable substrates 10 may be arranged apart from each other without having any direct contact portions (see FIG. 8). On the other hand, multiple stretchable wires 20 located between the same layers may be electrically connected by locally contacting each other. In other words, multiple stretchable wires 20 may be separated from each other except for local contact for conduction.

[0070] It should be noted that when a stretchable device includes a plurality of stretchable wires 20, not all of the stretchable wires 20 necessarily have to have a main wiring surface having the above-mentioned raised region 25. For example, among the plurality of stretchable wires 20, some of the stretchable wires 20 may not have a raised region 25. In the stretchable device of the present disclosure, from the viewpoint of suitably suppressing breakage and delamination of the stretchable wires 20 and further improving the reliability of the device, it is preferable that all of the stretchable wires 20 located inside the laminate 50 have a main wiring surface having a raised region 25. More preferably, all of the main wiring surfaces facing the stretchable substrate 10 have a raised region 25 in a portion thereof.

[0071] The above-described configuration is suitable in terms of delamination resistance between the stretchable substrate 10 and the stretchable wiring 20 located on the stretchable substrate 10, and may also be suitable in terms of peel resistance between the stretchable wiring 20 and any material that may be arranged opposite the main wiring surface of the stretchable wiring 20. For example, the stretchable wiring 20 having the structure of the present disclosure may also be suitable in terms of peel resistance when bonding with other resin layers such as a resin cover layer or adhesive layer that may be arranged on the main wiring surface.

[0072] (Third embodiment) Next, a description will be given of a stretchable device according to a third embodiment. The stretchable device differs from the stretchable device 100 according to the first embodiment in that the stretchable wiring 20 has a wiring main surface with a predetermined surface roughness Ra.

[0073] When emphasis is placed on the delamination resistance between the wiring 20 and the substrate 10, the surface roughness Ra of the wiring main surface having the above-mentioned raised regions 25 is preferably 1.8 μm or more and less than 7.7 μm, 2 μm or more and less than 7.5 μm, or 2.3 μm or more and less than 7 μm. When the surface roughness Ra is within the above-mentioned range, the stretchable substrate 10 and the stretchable wiring 20 can be more suitably bonded due to the anchor effect caused by the unevenness of the surface of the wiring main surface.

[0074] The surface roughness of the first wiring principal surface 21 (see FIG. 2 ) and the surface roughness of the second wiring principal surface 23 do not necessarily have to be the same. Preferably, both the first wiring principal surface 21 and the second wiring principal surface 23 of the stretchable wiring 20 may have a surface roughness Ra within the above-mentioned range. Furthermore, in order to place even greater importance on delamination resistance, when the wiring principal surface comprises a first region 25 and a second region 26, it is preferable that the surface roughness Ra is within the above-mentioned range in both the first region 25 and the second region 26. This allows the stretchable wiring 20 to obtain an anchor effect due to the surface irregularities across the entire wiring principal surface. Therefore, even when the stretchable device is stretched or contracted, the stretchable substrate 10 and the stretchable wiring 20 do not peel off, and can more preferably deform integrally.

[0075] In this specification, the surface roughness Ra refers to the arithmetic mean roughness in accordance with JIS B0601:2001. The surface roughness Ra of the wiring main surface is the arithmetic mean roughness measured on the cross section of the wiring main surface. The surface roughness Ra can be measured using, for example, a laser microscope.

[0076] (Method for fabricating a stretchable device) An exemplary method for fabricating a stretchable device according to the present disclosure will now be described.

[0077] First, a stretchable substrate 10 is prepared. After the stretchable substrate 10 is prepared, a stretchable wiring 20 is formed on the main surface 11 of the stretchable substrate 10 (see FIG. 7). 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 stretchable substrate 10 using screen printing, inkjet printing, or the like. This makes it possible to obtain a desired circuit pattern. In this case, by forming the wiring pattern so that a portion of the wiring is locally thick, a first region with a raised portion can be formed. The following two methods can be given as exemplary formation methods.

[0078] The first method involves providing a leveling time of approximately 5 seconds or more after printing the wiring, which allows for the formation of wiring in which some parts (e.g., the periphery of the wiring) are thick and other parts (e.g., the central part of the wiring) are thin.

[0079] In the second method, the conductive paste for the stretchable wiring (for example, a conductive paste containing a mixture of silver and resin) is printed on the stretchable substrate using screen printing and / or an inkjet method, etc. At this time, by adjusting the amount of paste discharged in a predetermined area according to the printing pattern, etc., it is possible to obtain a circuit pattern with a large thickness in a predetermined area of ​​the stretchable wiring.

[0080] Furthermore, the stretchable wiring 20 having the predetermined surface roughness Ra shown in the third embodiment can be obtained by controlling the mesh pattern in screen printing or the spray pattern of the conductive paste in inkjet printing when printing the wiring 20 on the stretchable substrate 10.

[0081] After forming a circuit pattern on the stretchable substrate 10, the conductive paste for stretchable wiring is dried and cured to form a stretchable wiring 20 whose thickness in a predetermined region is greater than that of other portions. That is, a stretchable wiring 20 having a wiring main surface including a first region 25 and a second region 26 is formed on the stretchable substrate 10. Note that printing may be performed not only on one wiring main surface, but also on both the first wiring main surface and the second wiring main surface. It is also possible to mount components on the stretchable wiring as needed.

[0082] When conducting electrical continuity among a plurality of stretchable wires 20 located on different stretchable substrates 10, vias may be formed at predetermined positions on the stretchable substrate 10 that can contact each of the plurality of stretchable wires 20. Vias may be formed by providing through holes at predetermined positions on the stretchable substrate and filling the through holes with a conductive material (for example, a conductive paste containing a mixture of silver and resin). The through holes can be formed by, for example, punching or laser processing. The planar shapes of the through holes and vias are not particularly limited and may be, for example, a perfect circle, an ellipse, or a polygon.

[0083] Next, the stretchable substrates 10 on which the desired circuit patterns have been formed by printing are stacked in the thickness direction X of the stretchable substrate 10, and pressed at a desired temperature and pressure to obtain a laminated stretchable device (see FIGS. 7 and 8). As a method for increasing the adhesion between the stretchable wiring 20 with the raised regions prepared earlier and the stretchable substrates located on both main surfaces thereof, for example, the following methods can be used.

[0084] When laminating the stretchable substrate 10 having the stretchable wiring 20, the temperature of the stretchable substrate 10 may be sufficiently raised to above the glass transition point of the resin used for the stretchable substrate 10. For example, if the material of the stretchable substrate 10 is a styrene-based elastomer, it may be heated to a temperature of about 80°C. Furthermore, since the stretchable wiring 20 made of a metal filler and a resin is desirably harder than the resin, the heating temperature is desirably a temperature below the softening point of the material of the stretchable wiring 20. By pressing the stretchable substrate 10 in the lamination direction X with a predetermined pressure within this temperature range, the stretchable wiring 20 in the raised regions 25 can be pressed into the stretchable substrate 10 on the printing surface side. As a result, in the stretchable wiring 20, each of the two opposing wiring main surfaces has a raised region 25, and each raised region 25 can be suitably engaged with the stretchable substrate 10, making it possible to obtain improved adhesion strength.

[0085] In this manner, a stretchable device according to the present disclosure can be produced. [Example]

[0086] Examples will be described below.

[0087] [Evaluation of Delamination Resistance of the First Embodiment (Stretchable Device with Raised Regions)] (1) Sample preparation Examples 1 to 6 and Comparative Examples 1 and 2 are samples of the stretchable device described above, formed by varying the thickness difference between the second region and the first region protruding relative to the second region on the wiring main surface facing the stretchable substrate. In all samples in the examples, the planar shape of the wiring main surface in cross-section is as shown in Fig. 1, and the cross-sectional shape is as shown in Fig. 3. That is, in this evaluation, a stretchable wiring was used that, in cross-section, had a first region along the periphery of the wiring main surface on both sides of the wiring main surface, and a second region in the central portion surrounded by the first region.

[0088] A composite paste of silver and acrylic resin was used as the material for the stretchable wiring. A stretchable wiring with a width of 2 mm and a length of 90 mm was printed on one of the stretchable substrates (styrene-based elastomer, 100 mm × 70 mm × 40 μm) using a screen printing method. In the samples of Examples 1 to 6, the stretchable wiring was printed so that the thickness of the wiring in a 200 μm-wide region along the periphery of the stretchable wiring increased. Then, a stretchable substrate was laminated and pressed at a predetermined pressure (1 MPa) to obtain a stretchable device.

[0089] (2) Measurement of sample Measurements of each sample were carried out by the following method, all at room temperature (approximately 25°C). (2-1) Thickness measurement The thickness of each region of the stretchable wiring was measured by cutting the fabricated stretchable device along the lamination direction and measuring the cross section using a microscope (for example, VHX series manufactured by Keyence).

[0090] (2-2) Measurement of peel elongation rate (delamination resistance) The fabricated stretchable device was subjected to a tensile test. Specifically, the stretchable device was clamped at both ends using a tensile tester, and the stretchable device was stretched along the longitudinal direction of the stretchable wiring at a rate of 36 mm / min, and the elongation rate at which peeling occurred between the stretchable substrate and the stretchable wiring (peel elongation rate) was recorded.

[0091] The measurement results for each sample of Examples 1 to 6 and Comparative Examples 1 and 2 are shown in Table 1. In the table, "thickness difference" refers to the value obtained by subtracting the thickness of the second region from the thickness of the first region.

[0092] [Table 1]

[0093] According to the above results, stretchable devices equipped with stretchable wiring with a relatively small thickness difference (4 μm or less) exhibited a peel elongation rate of approximately 60 to 70%, and the stretchable wiring and the stretchable substrate were able to elongate integrally to some extent as the stretchable device was stretched. Furthermore, the stretchable devices of Examples 1 to 6 equipped with a thickness difference of 5 μm or more exhibited a high peel elongation rate of 120% or more. This makes it clear that the first region (raised region) provided on the main surface of the wiring can greatly improve the peel elongation rate of the stretchable device.

[0094] Furthermore, when the stretched sample stretchable wire was observed with a stereomicroscope (or an electron microscope or an X-ray transmission device), no cracks were found in the stretchable wire. Therefore, according to the structure of the present disclosure, a stretchable device with good crack resistance can be provided even when the stretchable device is stretched to an elongation rate of 120% to 160%.

[0095] [Evaluation of Delamination Resistance and Breakage Resistance of Second Embodiment (Embodiment Having Stretchable Base Material Interposed Between Stretchable Wirings)] A sample of a stretchable device was prepared in the same manner as in the evaluation according to the first embodiment, and the peel elongation rate and the breaking elongation rate of the wiring were evaluated. In the examples, a sample was used in which a plurality of stretchable wirings 20 were arranged so as to overlap with each other via a stretchable substrate 10 (FIG. 9A). On the other hand, in the comparative examples, a sample was used in which a plurality of stretchable wirings 20 were arranged so as to directly overlap with each other in the stacking direction X between the stretchable substrates 10 (FIG. 9B). The evaluation results are shown in Table 2.

[0096] [Table 2]

[0097] From the above results, the stretchable device of Comparative Example 3, in which multiple stretchable wirings were arranged so as to directly overlap each other, and the stretchable device of Example 7, in which a stretchable substrate was interposed, obtained values ​​of approximately the same peel elongation rate. On the other hand, the stretchable device of Example 7 obtained results showing a wire breaking elongation rate that was 1.4 times that of Comparative Example 3. Therefore, it was found that by interposing a stretchable substrate so that multiple stretchable wirings do not directly overlap each other in the stacking direction, the bias in stress distribution in the overlapping portions of the stretchable wirings can be suitably alleviated, and wire breakage during stretching of the stretchable device can be suitably suppressed. In other words, according to the present disclosure, a stretchable device with high connection reliability that is more suitable in terms of wire breakage resistance during stretching of the stretchable device can be provided.

[0098] [Evaluation of Delamination Resistance and Breakage Resistance of Third Embodiment (Embodiment Having a Predetermined Surface Roughness Ra)] A sample was produced in the same manner as in Comparative Example 1 in the evaluation of the first embodiment, except that the surface roughness Ra of the first wiring main surface of the stretchable wiring was changed. The surface roughness Ra was adjusted by changing the mesh pattern and printing conditions in screen printing.

[0099] (2) Measurement of sample For each sample, the surface roughness Ra of the wiring principal surface was measured. Specifically, the stretchable device was cut along the stacking direction, and the cross section was observed using a laser microscope to measure the arithmetic mean surface roughness Ra of the second region on the first wiring principal surface of the stretchable wiring. Furthermore, the peel elongation rate and the wiring fracture elongation rate were measured by tensile testing. The measurement results are shown in Table 3.

[0100] [Table 3]

[0101] From the above results, it was found that in the wiring main surface having a raised region, the peel elongation rate improves as the surface roughness Ra of the wiring main surface increases. In other words, the rougher the wiring main surface, the more the adhesion between the stretchable substrate and the stretchable wiring improves due to the anchor effect. Therefore, according to the present disclosure, a more reliable stretchable device can be provided that is more suitable in terms of peel resistance between the substrate and wiring when the stretchable device is stretched. On the other hand, the stretchable device of Comparative Example 6, which had a surface roughness Ra of 7.9 μm, showed a high peel elongation rate but a low value for the fracture elongation rate of the wiring. This is thought to be because the strength of the wiring itself was reduced due to excessive roughening of the wiring main surface.

[0102] 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.

[0103] It should be noted that the embodiment of the present disclosure as described above includes the following preferred aspects. First aspect: A laminate formed by laminating a plurality of stretchable substrates and a stretchable wiring disposed inside the laminate, The elastic wiring has two wiring main surfaces that face each other in the stacking direction of the elastic base material, In a cross-sectional view, at least one of the wiring main surfaces includes a first region and a second region; The first region is a region in which a part of the wiring main surface is raised in the stacking direction more than the second region. Second aspect: In the first aspect, in a cross-sectional view, the thickness of the stretchable wire in the first region is greater than the thickness of the stretchable wire in the second region. Third aspect: In the first aspect or the second aspect, the stretchable device is such that the first region is on the periphery of the stretchable wiring when viewed from the stacking direction. Fourth aspect: In any one of the first to third aspects, the stretchable device is such that, when viewed from the stacking direction, the first region is located at least at a corner of the stretchable wire. Fifth aspect: In any one of the first to fourth aspects, the stretchable device is such that, when viewed from the stacking direction, the first region extends along the periphery of the stretchable wiring. Sixth aspect: In any one of the first to fifth aspects, each of the two wiring main surfaces has the first region, A stretchable device, in which, in a cross-sectional view, the first region on one of the wiring principal surfaces and the first region on the other of the wiring principal surfaces are raised in different directions along the stacking direction of the stretchable base material. Seventh aspect: In the sixth aspect, in a cross-sectional view, the first region on the one wiring principal surface and the first region on the other wiring principal surface are positioned coaxially along the stacking direction of the stretchable substrate. Eighth aspect: In any one of the first to seventh aspects, the stretchable device is such that the stretchable wiring is engaged with the stretchable substrate adjacent to the first region in the first region. Ninth aspect: In any one of the first to eighth aspects, the stretchable device is such that, in a cross-sectional view, the second region is a non-raised region. Tenth aspect: In any one of the first to ninth aspects, the stretchable device has a step structure provided on the wiring main surface by the first region and the second region in a cross-sectional view. Eleventh aspect: In any one of the first to tenth aspects, the first region is in contact with adjacent stretchable substrates. 12th aspect: In any one of the first to eleventh aspects, the stretchable device has, in a cross-sectional view, a thickness of the stretchable wiring in the first region that is smaller than a thickness of the stretchable substrate adjacent to the first region. Thirteenth aspect: In any one of the first to twelfth aspects, a plurality of the elastic wirings are provided, The plurality of elastic wires are arranged between the plurality of elastic substrates arranged in the stacking direction, A stretchable device, wherein the plurality of stretchable wirings are positioned so that, when viewed from the stacking direction, they have portions that at least partially overlap each other via the stretchable substrate. Fourteenth aspect: In any one of the first to thirteenth aspects, a plurality of the elastic wirings are provided, The plurality of elastic wires are arranged between the plurality of elastic substrates arranged in the stacking direction, The stretchable device, wherein the plurality of stretchable wires are arranged so as not to contact each other in the stacking direction. Fifteenth aspect: The stretchable device according to any one of the first to fourteenth aspects, further comprising the stretchable wiring on the outermost surface of the laminate. Sixteenth aspect: In any one of the first to fifteenth aspects, the stretchable device has a thickness of the stretchable wire in the first region that is 5 μm or more greater than a thickness of the stretchable wire in the second region in a cross-sectional view. Seventeenth aspect: In any one of the first to sixteenth aspects, the stretchable device has a surface roughness Ra of the wiring surface of the stretchable wiring of 2 μm or more and less than 7.5 μm. [Explanation of symbols]

[0104] 100, 101 to 105: Stretchable devices 10:Stretchable base material 11: Main surface 20:Stretchable wiring 21: First wiring surface 23: Second wiring surface 25: 1st area (raised area) 25a: Raised surface 26:Second area 30:Adhesive layer 50: Laminate X: Thickness direction of the elastic substrate

Claims

1. A laminate formed by laminating a plurality of stretchable substrates and a stretchable wiring disposed inside the laminate, The stretchable wiring has two wiring main surfaces that face each other in the stacking direction of the stretchable substrate, In a cross-sectional view, each of the two wiring main surfaces includes a first region and a second region, the first region is a region in which a part of the wiring main surface is raised in the stacking direction more than the second region, The first region is located on the periphery of the elastic wire and is positioned on an end side in the width direction of the elastic wire, In a cross-sectional view, the first region on one of the wiring principal surfaces and the first region on the other of the wiring principal surfaces are raised in different directions along the stacking direction of the stretchable base material. A stretchable device.

2. A laminate formed by laminating a plurality of stretchable substrates and a stretchable wiring disposed inside the laminate, The stretchable wiring has two wiring main surfaces that face each other in the stacking direction of the stretchable substrate, In a cross-sectional view, each of the two wiring main surfaces includes a first region and a second region, the first region is a region in which a part of the wiring main surface is raised in the stacking direction more than the second region, In a cross-sectional view, the thickness of the elastic wire in the first region is larger than the thickness of the elastic wire in the second region, In a cross-sectional view, the first region on one of the wiring principal surfaces and the first region on the other of the wiring principal surfaces are raised in different directions along the stacking direction of the stretchable base material. A stretchable device.

3. The stretchable device according to claim 1, wherein, in a cross-sectional view, a thickness of the stretchable wire in the first region is greater than a thickness of the stretchable wire in the second region.

4. The stretchable device according to claim 2 , wherein the first region is located on the periphery of the stretchable wiring when viewed from the stacking direction.

5. The stretchable device according to claim 1 or 2, wherein the first region is located at least at a corner of the stretchable wiring when viewed from the stacking direction.

6. The stretchable device according to claim 1 or 2, wherein the first region extends along a periphery of the stretchable wiring when viewed from the stacking direction.

7. 3. The stretchable device according to claim 1, wherein, in a cross-sectional view, the first region on the one wiring principal surface and the first region on the other wiring principal surface are coaxially positioned along the stacking direction of the stretchable substrate.

8. 3. The stretchable device of claim 1 or 2, wherein the stretchable wiring engages the stretchable substrate adjacent to the first region at the first region.

9. 3. The stretchable device of claim 1 or 2, wherein, in cross-section, the second region is a non-raised region.

10. The stretchable device according to claim 1 or 2, wherein, in a cross-sectional view, the first region and the second region provide a step structure on the wiring main surface.

11. 3. The stretchable device of claim 1 or 2, wherein the first regions contact adjacent stretchable substrates.

12. The stretchable device according to claim 1 or 2, wherein, in a cross-sectional view, a thickness of the stretchable wiring in the first region is smaller than a thickness of the stretchable substrate adjacent to the first region.

13. A plurality of the elastic wirings are provided, The plurality of elastic wires are arranged between the plurality of elastic substrates arranged in the stacking direction, The stretchable device according to claim 1 or 2, wherein the plurality of stretchable wirings are positioned so as to have at least partial overlapping portions with each other via the stretchable substrate, as viewed from the stacking direction.

14. A plurality of the elastic wirings are provided, The stretchable device according to claim 1 or 2, wherein the plurality of stretchable wirings are arranged between the plurality of stretchable substrates arranged in the stacking direction and are arranged so as to be non-contact with each other in the stacking direction.

15. The stretchable device according to claim 1 or 2, further comprising the stretchable wiring on the outermost surface of the laminate.

16. The stretchable device according to claim 1 or 2, wherein, in a cross-sectional view, the thickness of the stretchable wire in the first region is 5 μm or more greater than the thickness of the stretchable wire in the second region.

17. The stretchable device according to claim 1 or 2, wherein the surface roughness Ra of the wiring main surface of the stretchable wiring is 2 μm or more and less than 7.5 μm.

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