Stretchable device

Abstract

Provided is a stretchable device comprising: a plurality of stretchable base materials that are laminated to each other; a plurality of stretchable wires that are each disposed on each of the plurality of stretchable base materials; and a via that electrically connects at least two of the stretchable wires that overlap each other via the stretchable base material therebetween when viewed from the lamination direction of the stretchable base materials. In a cross-sectional view, among the plurality of stretchable base materials, at least one of the stretchable base materials on each of which the stretchable wire connected to the via is disposed includes protrusions protruding toward the stretchable wire, around the via.

Description

stretchable devices

[0001] The present disclosure relates to stretchable devices.

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

[0003] Japanese Patent Application Publication No. 7-226589

[0004] A known structure of a device including a substrate with multiple wirings is to route the multiple wirings across multiple layers in order to reduce the size of the device, and to electrically connect the wirings located on different layers through vias (Patent Document 1).

[0005] The present inventors have newly discovered a problem when applying a structure using a general via to a stretchable device. In a stretchable device, vias connecting stretchable wires located in different layers can be provided so as to penetrate the stretchable substrate, and the stretchability can change locally in the region where the vias are provided. Therefore, in the region near the via where the stretchability changes, stress concentration occurs due to the stretching of the stretchable device, making it easier for peeling to occur between the stretchable wire and the stretchable substrate.

[0006] 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 having a suitable via structure in which peeling of the stretchable substrate is suppressed.

[0007] The present inventors have invented a stretchable device that achieves the above-mentioned main object.

[0008] A stretchable device according to one embodiment of the present disclosure comprises a plurality of stretchable substrates stacked on one another, a plurality of stretchable wirings arranged on each of the plurality of stretchable substrates, and vias that electrically connect at least two of the stretchable wirings that overlap each other via the stretchable substrates when viewed from the stacking direction of the stretchable substrates, and in a cross-sectional view, at least one of the plurality of stretchable substrates, on which the stretchable wirings connected to the vias are arranged, comprises a convex portion that protrudes around the via toward the stretchable wiring side.

[0009] According to one embodiment of the present disclosure, a stretchable device is provided that has a suitable via structure in which peeling of the stretchable substrate is suppressed.

[0010] FIG. 1A is a plan view of a stretchable device according to a first embodiment of the present disclosure. FIG. 1B is a plan view of a stretchable device according to a modified version of the first embodiment of the present disclosure. FIG. 2 is a cross-sectional view schematically showing a cross section A-A of the stretchable device shown in FIG. 1A. FIG. 3 is a cross-sectional view schematically showing a stretchable device according to a modified version of the first embodiment of the present disclosure. FIG. 4 is a cross-sectional view schematically showing a stretchable device according to a modified version of the first embodiment of the present disclosure. FIG. 5 is a cross-sectional view schematically showing a stretchable device according to a modified version of the first embodiment of the present disclosure. FIG. 6 is a cross-sectional view schematically showing a stretchable device according to a second embodiment of the present disclosure. FIG. 7 is a cross-sectional view schematically showing a stretchable device according to a modified version of the second embodiment of the present disclosure. FIG. 8 is a cross-sectional view schematically showing a stretchable device according to a modified version of the second embodiment of the present disclosure. FIG. 9A is a cross-sectional view schematically showing a stretchable device according to a modified version of the second embodiment of the present disclosure. FIG. 9B is a cross-sectional view schematically showing a stretchable device according to a modified version of the second embodiment of the present disclosure. FIG. 9C is a cross-sectional view schematically showing a stretchable device according to a modified version of the first embodiment of the present disclosure. Fig. 10 is a cross-sectional view schematically showing a stretchable device according to a modified version of the second embodiment of the present disclosure. Fig. 11 is a cross-sectional view schematically showing a stretchable device according to a third embodiment of the present disclosure. Fig. 12 is a cross-sectional view schematically showing a stretchable device according to a fourth embodiment of the present disclosure. Fig. 13 is a plan view schematically showing a stretchable device according to a fifth embodiment of the present disclosure. Fig. 14 is a cross-sectional view schematically showing the B-B cross section of the stretchable device shown in Fig. 13.

[0011] The following describes specific embodiments of the present disclosure. The applicant provides the following description and examples to enable those skilled in the art to fully understand the present disclosure, and it should be noted that these are not intended to limit the subject matter described in the claims. In other words, the present disclosure is not particularly limited to the preferred embodiments described below, and can be implemented with appropriate modifications within the scope of its purpose. For convenience, the present disclosure may be divided into embodiments and examples to facilitate explanation or understanding of the key points. However, partial substitution and / or combination of the configurations shown in different embodiments is possible. In describing such embodiments, redundant explanations of substantially identical features may be omitted, and only differences may be described. In particular, similar effects resulting from similar configurations may not be mentioned in each embodiment.

[0012] In this specification, the terms "thickness direction of the stretchable device," "thickness direction of the stretchable substrate," "stacking direction of the stretchable substrate," and "stacking direction" may be used interchangeably. Such a direction corresponds to direction Z in the drawings.

[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 other words, the shape of the stretchable device cut along a plane parallel to the thickness direction). When the stretchable device has a layered structure including multiple stretchable substrate layers, 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 stacking direction of the stretchable substrates (in other words, the shape of the stretchable device cut along a plane parallel to the stacking direction). Furthermore, as used herein, the term "planar view" refers to a sketch of the object as viewed from above or below along the thickness direction (or stacking 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] The various numerical ranges referred to herein are intended to include the lower and upper numerical limits themselves unless otherwise specified, and the term "about" means that there may be a variation or difference of a few percent, e.g., ±10%.

[0016] As used herein, "vertical" and "substantially vertical" do not necessarily mean completely "vertical," but include aspects that are slightly deviated from the completely vertical (for example, a range of ±10°, e.g., ±5°, from the completely vertical).

[0017] Furthermore, in this specification, "substantially parallel" does not necessarily mean completely "parallel," but includes a state where the parallelism is slightly deviated from the parallelism (for example, within a range of ±10° from completely parallelism, e.g., within a range of ±5°).

[0018] [Basic Configuration of Stretchable Device] The structure of a stretchable device will be described with reference to Figures 1A, 1B, and 2. Figures 1A and 1B are plan views exemplarily showing stretchable devices 1A and 1B according to an embodiment of the present disclosure. Figure 2 is a cross-sectional view schematically showing the A-A cross section of the stretchable device 1A shown in Figure 1A. Note that, unless otherwise specified, cross-sectional views in this specification show cross sections that pass through the center of the via 50 and are parallel to the thickness direction Z of the stretchable device.

[0019] The stretchable device 1A includes a plurality of stretchable substrates 10, 30 stacked on top of each other. Stretchable wiring 20, 40 may be arranged on the main surfaces of the stretchable substrates 10, 30, respectively. The stretchable device may have a multi-layer structure in which a plurality of stretchable substrates 10, 30 are stacked with their main surfaces facing each other. In other words, a plurality of stretchable substrates 10 may be stacked in the thickness direction Z of the stretchable substrate 10 to form a laminate. The number of stretchable substrates 10 to be stacked is not particularly limited.

[0020] Here, the "principal surface" of the stretchable substrate refers to a surface extending in a direction different from the thickness direction Z of the stretchable substrate, for example, a surface extending in the X-Y direction substantially perpendicular to the thickness direction Z of the stretchable substrate. The "principal surface" corresponds to a surface that is clearly larger in area than other surfaces of the sheet-like stretchable substrate (for example, side surfaces extending substantially parallel to the thickness direction Z). The sheet-like or film-like stretchable substrate 10, 30 may extend along the stretch direction of the stretchable device. In such a structure, the principal surface of the stretchable substrate 10, 30 can also be interpreted as a surface extending along the stretch direction of the stretchable substrate 10, 30. The principal surface can also be interpreted as a surface extending along the extension direction of the stretchable wiring described below.

[0021] Although the drawings show stretchable devices extending in a specific direction for clarity, the shape of the stretchable device is not particularly limited. The planar shape of the stretchable device is also not particularly limited, and can be, for example, a quadrilateral (e.g., square, rectangle, etc.), a polygon such as a triangle, a circle, an ellipse, a semicircle, a crescent, or an irregular shape.

[0022] The main components included in the stretchable device of the present disclosure will now be described with reference to FIGS. 1A and 2.

[0023] (Stretchable Substrates 10, 30) The stretchable substrates 10, 30 (hereinafter also simply referred to as "substrates") may be sheet- or film-like stretchable substrates, and may be made of, for example, a stretchable resin material. In this specification, "stretchability" simply means the property of being able to stretch and contract, and can also be referred to as stretchability, stretchable, etc. More specifically, it means the property of being able to stretch from a non-stretched state, which is the normal state in which no tensile stress is applied, by applying tensile stress, and being able to contract when released from the stretched state. Although only two stretchable substrates 10 and 30 are shown in the drawings, one or more additional stretchable substrates may be laminated in the stretchable device.

[0024] A resin material having elasticity may be used as the elastic substrate. For example, the elastic substrate preferably contains at least one resin selected from the group consisting of acrylic resins, urethane resins, and styrene resins. Examples of urethane resins include thermoplastic polyurethanes. Exemplary styrene resins include styrene-butadiene-styrene block copolymers (SBS) and styrene-ethylene-butylene-styrene block copolymers (SEBS). Furthermore, the multiple elastic substrates stacked on top of each other may each be made of the same material, or may be made of different materials.

[0025] The thickness of the stretchable substrates 10, 30 is not particularly limited, but when prioritizing the stretchability of the device, it is preferably 1 mm or less, more preferably 100 μm or less, and even more preferably 50 μm or less. When the stretchable device is attached to a living body, when prioritizing the viewpoint of suppressing inhibition of stretching of the living body surface, it is preferably 100 μm or less, more preferably 1 μm or less. Furthermore, when prioritizing the mechanical strength of the stretchable device, the thickness of the stretchable substrate is preferably 0.5 μm or more. Furthermore, each of the multiple stretchable substrates stacked on top of each other may have the same thickness or may have different thicknesses.

[0026] (Stretchable wiring 20, 40) A stretchable wiring 20 or 40 is disposed on the stretchable substrates 10, 30, respectively. That is, the stretchable wirings (hereinafter also simply referred to as "wiring") 20, 40 are disposed on different stretchable substrates. As a result, the stretchable wirings 20, 40 may be located at different heights in a cross-sectional view. Hereinafter, for convenience of explanation, each of the multiple stretchable substrates 10, 30 will be referred to as a first stretchable substrate 10 and a second stretchable substrate 30, and the stretchable wiring 20 disposed on the first stretchable substrate 10 will be referred to as a first stretchable wiring 20, and the stretchable wiring 40 disposed on the second stretchable substrate 30 will be referred to as a second stretchable wiring 40. As shown in FIG. 2 , the second stretchable substrate 30 is an insulating substrate located between the first stretchable wiring 20 and the second stretchable wiring 40, and may also be referred to as, for example, an "interlayer insulating layer" or an "interlayer substrate".

[0027] Note that "the stretchable wiring is disposed on the stretchable substrate" can be rephrased as "the stretchable wiring and the stretchable substrate are in contact." For example, the first stretchable wiring 20 shown in Figure 2 is located between the first stretchable substrate 10 and the second stretchable substrate 30, and is in contact with both the first stretchable substrate 10 and the second stretchable substrate 30. Therefore, it can also be interpreted that the first stretchable wiring 20 is disposed on the main surface 10a of the first stretchable substrate 10 and / or the main surface 30b of the second stretchable substrate 30 facing the main surface 10a (see Figure 9A).

[0028] The stretchable wiring may be composed of a mixture of conductive particles and a resin. The conductive particles may be, for example, at least one metal powder selected from the group consisting of Ag (silver), Cu (copper), and Ni (nickel). 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 also not particularly limited, but may be, for example, a substantially spherical, substantially elliptical, polyhedral, flat, or irregular shape such as a shape with protrusions. 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. The different stretchable wirings 20, 40 may be composed of the same material or different materials.

[0029] The thickness of the elastic wire is preferably 100 μm or less, more preferably 50 μm or less. Furthermore, when importance is placed on the strength of the elastic wire, the thickness of the elastic wire is preferably 1 μm or more.

[0030] Furthermore, the stretchable wiring 20, 40 may extend in any direction. Preferably, the stretchable wiring 20, 40 may extend along the extension direction of the main surface of the stretchable substrate 10, 30. Furthermore, when viewed from the thickness direction Z of the stretchable substrate, the stretchable wiring 20, 40 does not necessarily have to be arranged in a straight line, and may be arranged, for example, in a curved line. Furthermore, the stretchable wiring 20, 40 does not necessarily have to extend in one direction. For example, the stretchable wiring 20, 40 may be branched. The number of stretchable wirings arranged on one stretchable substrate is not particularly limited, and one or more wirings may be arranged.

[0031] Furthermore, when a stretchable device includes three or more stretchable substrates, stretchable wiring does not necessarily have to be arranged on all of the stretchable substrates. That is, the stretchable device may include a stretchable substrate on which no stretchable wiring is arranged. Furthermore, the stretchable wiring does not necessarily have to be arranged on only one main surface of the stretchable substrate. For example, a plurality of stretchable wirings may be arranged on both sides of the stretchable substrate.

[0032] (Via 50) The stretchable device further includes vias 50 that electrically connect multiple stretchable wirings 20, 40 located at different heights in a cross-sectional view. For example, as shown in FIG. 2 , the vias 50 may electrically connect the first stretchable wiring 20 and the second stretchable wiring 40 that are arranged facing each other with the second stretchable substrate 30 sandwiched between them. Note that the first stretchable wiring 20 and the second stretchable wiring 40 do not necessarily have to face each other entirely, and may be arranged facing each other partially. The vias 50 may be provided at a position where the wirings are arranged facing each other. The first stretchable wiring 20 and the second stretchable wiring 40 may be electrically connected to each other via the vias 50 in the stacking direction Z. More specifically, when viewed from the stacking direction Z of the stretchable substrates 10, 30, the vias 50 may be positioned in a region where the first stretchable wiring 20 and the second stretchable wiring 40 overlap each other, and the wirings may be electrically connected to each other via the vias 50. The via 50 may have a second main surface 50b in contact with the first elastic wire 20 and a first main surface 50a in contact with the second elastic wire 40.

[0033] The via 50 may penetrate a stretchable substrate located between multiple wirings connected by the via 50. For example, as shown in FIG. 2, the via 50 may penetrate a second stretchable substrate 30 located between a first stretchable wiring 20 and a second stretchable wiring 40. Although not shown, the stretchable substrate through which the via 50 penetrates is not necessarily limited to one stretchable substrate. For example, multiple stretchable substrates may be located between the first stretchable wiring 20 and the second stretchable wiring 40 connected by the via 50. In such a configuration, the via 50 may penetrate multiple stretchable substrates present between the wirings. As a result, stretchable wirings present at different positions in the stacking direction across the stretchable substrate may be electrically connected via the via 50.

[0034] The via 50 may be a mixture of conductive particles and a resin. The conductive particles may be, for example, at least one metal powder selected from the group consisting of Ag (silver), Cu (copper), and Ni (nickel). 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 also not particularly limited, but may be, for example, a substantially spherical, substantially elliptical, polyhedral, flat, or irregular shape such as a shape with protrusions. 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. For example, the via 50 may be made of the same material as the stretchable wiring 20, 40, or may be made of different materials. For example, the via 50 and at least one of the stretchable wiring 20, 40 may be integrally formed using the same material.

[0035] The via 50 penetrates at least the stretchable substrate 30 and extends in a direction different from the extension direction of the stretchable substrate 30. In such a structure, the via 50 may have poor stretchability, particularly in the extension direction of the stretchable substrate. Therefore, in a structure including the via 50 described above, the stretchability of the stretchable device may decrease at the location where the via 50 is provided. The present inventors have found that a sudden decrease in the stretchability of the stretchable device at the location where the via 50 is provided can cause stress to concentrate near the via 50. They have also found that this stress concentration can cause peeling between the via 50 and / or the stretchable wiring 20, 40 connected to the via 50 and the stretchable substrate 10, 30, resulting in the risk of wiring breakage. In view of the above problems, the present inventors have invented a stretchable device that uses a novel structure described below to suppress peeling between the stretchable substrates 10, 30 and suitably connect stretchable wirings via the via 50.

[0036] First Embodiment Based on the details of the main components of the stretchable device described above, the following describes the characteristic parts of the stretchable device according to the first embodiment of the present disclosure.

[0037] In the stretchable device of the present disclosure, at least one stretchable substrate of the multiple stretchable substrates 10, 30 comprises a convex portion 12 that protrudes around the via 50 toward the stretchable wiring 20 / 40 connected to the via 50. More specifically, for example, as shown in FIG. 2 , the first stretchable substrate 10 may be provided with a convex portion 12 that is disposed on the first stretchable substrate 10 and protrudes toward the first stretchable wiring 20 connected to the via 50. Alternatively or additionally, as shown in FIG. 6 , the second stretchable substrate 30 may be provided with a convex portion 32, and the convex portion 32 may be disposed on the second stretchable substrate 30 and protrude toward the second stretchable wiring 40 connected to the via 50. Hereinafter, first, as a first embodiment, a stretchable device in which the first stretchable substrate 10 comprises a convex portion 12 will be described.

[0038] The first stretchable substrate 10 is a stretchable substrate that does not have the vias 50 penetrating it, among the stretchable substrates that support the stretchable wiring electrically connected by the vias 50. In the first stretchable substrate 10, the main surface facing the first stretchable wiring 20 is not a uniform flat surface, but has convex portions 12. This allows a member in contact with the convex portions 12 (for example, the first stretchable wiring 20) to physically catch on the convex portions 12. For example, the first stretchable substrate 10 can mechanically interlock with another member in contact with the convex portions 12. This can improve the peel resistance of the first stretchable substrate compared to when the main surface of the first stretchable substrate 10 is a uniform flat surface.

[0039] The protrusions 12 may be raised around the vias 50 so that at least a portion of them digs into the first stretchable wiring 20. The anchor effect caused by the digging of the protrusions 12 can improve the peel resistance of the stretchable substrate 10. Therefore, according to the present disclosure, a stretchable device having a more suitable via structure with excellent peel resistance of the stretchable substrate can be provided.

[0040] In this specification, "around the via 50" refers to a region ranging from the outer contour of the via 50 toward the outside of the via 50, as viewed from the stacking direction Z, to a region of 500 μm or less. For example, the protrusion 12 may be formed in a region overlapping the via 50, as viewed from the stacking direction Z (see FIG. 1A). Alternatively, the protrusion 12 may not overlap the via 50, as viewed from the stacking direction Z, but may be located in a region of 500 μm or less from the outer contour of the via 50 toward the outside of the via 50 (see FIG. 1B). By positioning the protrusion 12 around the via 50, the peel resistance of the stretchable substrate 10 near the via 50, where stress is likely to concentrate and peeling is likely to occur, can be improved. Therefore, a stretchable device with better peel resistance can be obtained.

[0041] (Modifications of First Embodiment) Various modifications can be adopted for the stretchable device according to the first embodiment.

[0042] As shown in FIG. 2 , the first stretchable wiring 20 facing the first stretchable substrate 10 may have recesses 22 that are relatively recessed on the main surface facing the protrusions 12. In such a structure, the protrusions 12 of the first stretchable substrate 10 may protrude toward the recesses 22 of the first stretchable wiring 20. The protrusions 12 of the first stretchable substrate 10 and the recesses 22 of the first stretchable wiring 20 may face each other in the thickness direction Z of the stretchable device. The recesses 22 may be positioned so as to overlap with the protrusions 12 when viewed from the stacking direction Z. The protrusions 12 of the first stretchable substrate 10 may protrude so as to bite into the recesses 22 of the first stretchable wiring 20. The first stretchable substrate 10 can be more suitably adhered to the first stretchable wiring 20 due to the anchor effect acting between the recesses 22 and the protrusions 12 of the first stretchable wiring 20. This can improve the peel resistance between the first stretchable substrate 10 and the first stretchable wiring 20 .

[0043] The convex portions 12 may have a structure in which at least a portion thereof enters the concave portions 22. In other words, the concave portions 22 and the convex portions 12 do not have to have complementary shapes. In such a structure, a gap may exist between the convex portions 12 and the stretchable wiring 20. Alternatively, the concave portions 22 may have a shape complementary to that of the convex portions 12. The convex portions 12 of the stretchable substrate and the concave portions 22 of the stretchable wiring 20 may have complementary shapes that allow them to intermesh with each other. This allows an anchor effect to act favorably between the stretchable wiring 20 connected to the via 50 and the stretchable substrate 10.

[0044] As shown in FIG. 2 , in an embodiment in which the via 50 and the protrusion 12 are arranged at positions where they overlap each other, the thickness of the stretchable wire 20 may be reduced from the end toward the position where it overlaps with the protrusion 12 when viewed from the stacking direction Z. In such a structure, the thickness of the stretchable wire 20 arranged on the stretchable substrate 10 including the protrusion 12 may be gradually reduced toward the point where it overlaps with the center of the via 50. In general, the stretchability of a stretchable material decreases as the thickness of the material increases. Therefore, by gradually changing the thickness of the stretchable wire 20, a sudden change in stretchability in the region including the via 50 can be suppressed. This alleviates stress concentration associated with a sudden change in stretchability, making it possible to suitably suppress peeling of the stretchable substrate 10.

[0045] 3 and 4 are cross-sectional views schematically showing a stretchable device according to a further modified aspect of the first embodiment. FIG. 3 is a cross-sectional view schematically showing a stretchable device 1C according to a modified aspect of the first embodiment of the present disclosure. As shown in the figures, the stretchable wire 20 located on the protrusion 12 may have a curved portion 24 that curves to follow the outer contour of the protrusion 12 in a cross-sectional view. The curved portion 24 is a portion that includes a non-linear shape and encompasses both bending and curvature. Due to such curved portion 24, the stretchable wire 20 may have a portion that is concave along the outer contour of the protrusion 12. The stretchable wire 20 extends along the main extension direction X of the stretchable substrate 10, and may bend so as to incline toward the via 50 at the location where the protrusion 12 is formed. By bending the stretchable wire 20 to have the curved portion 24 that follows the protrusion 12, the thickness of the stretchable wire 20 is not excessively reduced even in the recess 22. Therefore, such a structure can be useful in that it can reduce the risk of breakage of the stretchable wiring 20 due to a reduction in the wiring thickness. On the other hand, the curved portion 24 does not necessarily have to completely follow the outer contour of the convex portion 12.

[0046] 4 is a cross-sectional view schematically showing a stretchable device 1D according to a modified example of the first embodiment of the present disclosure. As shown in the figure, in a cross-sectional view, the via 50 may have a tapered shape that gradually tapers along the stacking direction Z. Specifically, the via 50 may have a tapered shape that gradually tapers toward either the first stretchable wire 20 or the second stretchable wire 40 that are electrically connected to each other by the via 50. For example, the via 50 may have a tapered shape that gradually tapers from the second stretchable wire 40 side toward the first stretchable wire 20 side. Alternatively, the via 50 may have a tapered shape that gradually tapers from the first stretchable wire 20 side toward the second stretchable wire 40 side. In a cross-sectional view, a side surface 50c connecting the first main surface 50a and the second main surface 50b (see FIG. 2) of the via 50 may be inclined with respect to the thickness direction Z.

[0047] In this structure, the width dimension of the via 50 changes gradually along the thickness direction Z. This structure can be interpreted as a structure in which the thickness dimension of the via 50 gradually increases toward the center of the via 50. The stretchability of the stretchable device can gradually increase toward the center as the thickness of the via 50 increases, and abrupt changes in stretchability due to the presence of the via 50 are suppressed. This reduces stress concentration caused by abrupt changes in stretchability, and can suitably suppress peeling of the stretchable substrate 10 in the vicinity of the via 50.

[0048] When viewed from the stacking direction Z, the protrusion 12 may be positioned along the periphery of the via 50. For example, when viewed from the stacking direction Z, the protrusion 12 may be positioned in a region that overlaps with the periphery of the via 50 (see FIG. 1A ). Alternatively, the protrusion 12 may be positioned along the periphery of the via 50 in a region that does not overlap with the via 50 when viewed from the stacking direction Z. In other words, the protrusion 12 may be positioned on the outer periphery of the via 50 when viewed from the stacking direction Z (see FIG. 1B ). The recess 22 is positioned so as to overlap with the protrusion 12 when viewed from the stacking direction Z, and the recess 22 may also be positioned along the periphery of the via 50.

[0049] For example, the protrusions 12 and recesses 22 may be formed continuously along the periphery of the via 50 (see FIGS. 1A and 1B ). Alternatively, the protrusions 12 and recesses 22 may be formed intermittently along the periphery of the via 50. Positioning the protrusions 12 and recesses 22 along the periphery of the via 50 reduces the difference in stretchability between the region including the via 50 and the region adjacent to the via 50. The stretchability can be gradually changed from the region adjacent to the via 50 to the region including the via 50. This reduces abrupt changes in stretchability due to the presence of the via 50, and can suppress local stress concentration near the via 50. This makes it possible to suppress peeling of the stretchable substrate 10 caused by stress concentration.

[0050] 5 , the first stretchable substrate 10 that is not penetrated by the via 50 may have a relatively large thickness in a region that is relatively closer to the via 50 than the protrusion 12, and a relatively small thickness in a region that is relatively more distal to the via 50 than the protrusion 12. For example, the first stretchable substrate 10 may have a relatively large thickness dimension in a region that overlaps with the via 50, and a relatively small thickness dimension in a region that does not overlap with the via 50. That is, in a cross-sectional view, the thickness of the first stretchable substrate 10 may gradually increase in the region that overlaps with the via 50 so as to rise toward the via 50. The first stretchable wiring 20 disposed on the stretchable substrate 10 can extend so as to be lifted toward the second stretchable wiring 40 that is connected via the via 50 as the thickness of the stretchable substrate 10 increases. That is, in a cross-sectional view, the stretchable device may include a portion around the via 50 where the distance between the stretchable wiring 20 and the stretchable wiring 40 decreases toward the via 50. This makes it possible to further reduce the thickness of the via 50 connecting the stretchable wiring 20 and the stretchable wiring 40, thereby suppressing an excessive decrease in stretchability in the arrangement region of the via 50 and the region around the via 50.

[0051] The thickness dimension of the stretchable substrate 10 may vary gradually in the region where the protrusions 12 are formed and / or around the region 15 overlapping with the via 50. As shown in FIG. 5 , the thickness dimension of the first stretchable substrate 10, which is not penetrated by the via 50, may include a portion in which the thickness dimension gradually increases with increasing distance from the protrusions 12 and the via 50 in the region 17 that does not overlap with the via 50 as viewed in the thickness direction Z. This can also be interpreted as a structure including a portion in which the thickness dimension of the first stretchable substrate 10 gradually increases with increasing distance from the region 15 overlapping with the via 50 as viewed in the thickness direction Z. In such a structure, the first stretchable wiring 20 may extend at an angle so as to gradually bite into the interior of the first stretchable substrate toward the protrusions 12 in a cross-sectional view, and may bend on the protrusions 12 to follow the shape of the protrusions 12, thereby forming recesses 22.

[0052] For example, the thickness dimension of the first stretchable substrate 10 may include a portion that gradually decreases toward the protrusion 12 in the region 17 that does not overlap with the via 50 when viewed from the stacking direction Z. Specifically, the thickness dimension of the first stretchable substrate 10 located on the side farther from the via 50 than the protrusion 12 may include a portion that gradually increases with increasing distance from the protrusion 12, and then extend at a substantially constant thickness. In this way, by gradually changing the thickness of the stretchable substrate 10 around the via 50, it is possible to prevent a sudden change in the stretchability of the entire stretchable device around the via 50. This can suitably prevent stress concentration associated with changes in stretchability and peeling of the stretchable substrate 10 resulting therefrom.

[0053] Second Embodiment Next, a description will be given of a stretchable device according to a second embodiment. Fig. 6 is a schematic cross-sectional view of a stretchable device 1F according to a second embodiment of the present disclosure.

[0054] Similar to the convex portions 12 of the first stretchable substrate 10 described above, convex portions 32 may be formed on the second stretchable substrate 30. That is, the second stretchable substrate 30 may be provided with convex portions 32 that protrude toward the second stretchable wiring 40. The characteristics described above for the convex portions 12 can also be applied to the convex portions 32 formed on the second stretchable substrate 30. Similarly, the characteristics of the convex portions 32 described below can also be applied to the convex portions 12 formed on the first stretchable substrate 10. Below, as a second embodiment, a stretchable device in which the second stretchable substrate 30 is provided with convex portions 32 that protrude toward the second stretchable wiring 40 will be described.

[0055] The second stretchable substrate 30 is a substrate that supports the second stretchable wire 40, which is one of a plurality of stretchable wires electrically connected by vias 50. The second stretchable substrate 30 is interposed between two stretchable wires 20, 40 that are electrically connected to each other via the via 50. The via 50 may penetrate the second stretchable substrate 30. The second stretchable substrate 30 may be in contact with both the side surface 50c of the via 50 and the second stretchable wire 40 connected to the via 50. By providing the second stretchable substrate 30 with a convex portion 32 that protrudes toward the second stretchable wire 40, an anchor effect occurs in the convex portion 32 of the second stretchable substrate 30, making it possible to improve the peel resistance of the second stretchable substrate 30.

[0056] (Modifications of Second Embodiment) Various modifications can be adopted for the stretchable device according to the second embodiment. Similar to the recess 22 of the first stretchable wiring 20 described above, a recess 42 may be formed in the second stretchable wiring 40 connected to the via. That is, the second stretchable wiring 40 may be provided with a recess 42 that is relatively recessed on the main surface 40b facing the protrusion 32. The characteristics described above for the recess 22 can also be applied to the recess 42 formed in the second stretchable wiring 40. Similarly, the characteristics of the recess 42 described below can also be applied to the recess 22 formed in the first stretchable wiring 20. By engaging the protrusion 32 of the second stretchable substrate 30 with the recess 42 of the second stretchable wiring 40 connected to the via 50, it is possible to improve the peel resistance of the second stretchable substrate 30 from the second stretchable wiring 40.

[0057] At least one of the first elastic wire 20 and the second elastic wire 40 may have a recessed portion corresponding to a protruding portion of the opposing substrate. For example, both the first elastic wire 20 and the second elastic wire 40 may have recessed portions 22, 42.

[0058] 7 to 10 are cross-sectional views schematically showing stretchable devices 1G to 1L according to modified aspects of the second embodiment. As shown in FIG. 7 , in a cross-sectional view, the main surface 40b of the second stretchable wire 40 may be recessed in a direction opposite to the via 50 in a region overlapping with the via 50, forming a recess 42. In such a structure, the recess 42 of the second stretchable wire may be formed over at least the region overlapping with the via 50. The via 50 may be arranged so that a portion of it extends toward the recess 42 of the second stretchable wire. In short, a portion of the via 50 may be located within the recess 42 of the second stretchable wire. The protrusion 32 formed on the second stretchable substrate 30 may be wedged between the recess 42 of the second stretchable wire and the side surface 50c of the via 50 that extends into the recess 42. The protrusion 32 of the second stretchable substrate 30 may be in contact with both the second stretchable wire 40 and the side surface 50c of the via 50. Furthermore, when viewed from the stacking direction Z, the convex portions 32 may be formed at positions adjacent to the vias 50. In such a structure, the convex portions 32 can also be interpreted as protruding so as to dig into the interface between the stretchable wiring 20 and the side surface 50c of the via 50. This makes it possible to increase the contact area between the second stretchable substrate 30 and the second stretchable wiring 40 and the vias 50. Furthermore, by providing the second stretchable substrate 30 with the convex portions 32 that protrude so as to dig into the second stretchable wiring 40 side, peeling of the second stretchable substrate 30 can be suitably suppressed due to the anchor effect obtained by the convex portions 32.

[0059] The shape of the protrusions 32 in cross-sectional view is not particularly limited. For example, as shown in FIGS. 5 and 6 , the protrusions 32 may have two surfaces and a generally inverted V-shaped outer contour that widens from the tip to the base of the protrusions 32 in cross-sectional view, or may have a generally inverted U-shaped outer contour that includes a curved surface at the tip of the protrusions 32. Alternatively, as shown in FIG. 8 , the protrusions 32 may have a polygonal shape with at least three surfaces. For example, the protrusions 32 may have a generally rectangular cross-sectional shape, or as shown in FIG. 9A , they may have a trapezoidal shape whose width gradually decreases toward the tip of the protrusions 32. In such a structure, the protrusions 32 can contact the stretchable wiring 40 and / or vias 50 on at least three surfaces. This can increase the contact area between the stretchable substrate 30 and the stretchable wiring 40 and / or vias 50.

[0060] Furthermore, the at least three surfaces may include surfaces extending in different directions. For example, as shown in FIGS. 8 and 9A , the protrusions 32 may have two side surfaces 32b extending up from the stretchable substrate 30 at the base of the protrusions 32, and a top surface 32a connecting the two side surfaces. Furthermore, the recesses 42 overlapping the protrusions 32 when viewed from the stacking direction Z may also have a shape complementary to that of the protrusions 32. That is, the recesses 42 may have two side surfaces facing the inside of the recesses 42 and a bottom surface of the recesses 42. This allows the stretchable substrate 30 to contact the stretchable wiring 40 and / or vias 50 on surfaces extending in multiple directions. Therefore, when stress acts in various directions during the stretching of the stretchable device, the stress can be more suitably distributed at the contact surfaces between the stretchable substrate 30 and the stretchable wiring 40 and / or vias 50. This can improve the peel resistance of the stretchable substrate 30.

[0061] As shown in FIGS. 8 and 9A , in a cross-sectional view, the widths of the top surfaces 32 a of the convex portions 32 located on both sides of the via 50 are defined as W1 and W2, respectively. Furthermore, the shortest distance between the stretchable substrates 30 located on both sides of the via 50, sandwiching the area in which the via 50 is disposed, is defined as W3. In a cross-sectional view, the total width dimension (W1 + W2) of the top surfaces 32 a located on both sides of the via 50 is preferably 0.8% or more of the shortest distance W3 between the stretchable substrates 30 located on both sides of the via 50, more preferably 1% or more, and even more preferably 1.2% or more. Furthermore, the total width dimension (W1 + W2) of the top surfaces 32 a in a cross-sectional view is preferably 100% or less of the shortest distance W3 between the stretchable substrates 30 located on both sides of the via 50, more preferably 50% or less, and even more preferably 1.5% or less. In this specification, the term "total width dimension of the top surfaces of the convex portions" refers to the sum of the width dimensions of the top surfaces of the convex portions located around one via 50. That is, as shown in Fig. 8, when the protrusions 32 are positioned on both sides of the via 50, the "total width dimension of the top surfaces of the protrusions" corresponds to the sum (W1 + W2) of the width dimensions of the two protrusions 32 in a cross-sectional view. By providing the top surfaces of the protrusions with a total width dimension within the above-mentioned range, it is possible to ensure a sufficient contact area between the protrusions 32 and the stretchable wiring 40 while favorably exerting the anchor effect of the protrusions 32. This can further improve the peel resistance between the stretchable substrate 30 and the stretchable wiring 40.

[0062] In one aspect, in a cross-sectional view passing through the center of the via 50, the total width dimension (W1 + W2) of the top surface 32a of the convex portion 32 is preferably 0.8% or more of the maximum width dimension W4 of the via 50 in the cross-sectional view shown in FIGS. 8 and 9A , more preferably 1% or more, and even more preferably 1.2% or more. Furthermore, the total width dimension (W1 + W2) of the top surface 32a in the cross-sectional view is preferably 100% or less of the maximum width dimension W4 of the via 50, more preferably 50% or less, and even more preferably 10% or less. In this specification, the "maximum width dimension W4 of the via 50" refers to the maximum value of the width of the via 50 observed in a cross-sectional view passing through the center of the via 50. When the top surfaces of the convex portions have a total width dimension in the above-mentioned range, the stretchable substrate 30 and the stretchable wiring 40 can be suitably adhered to each other, and the peel resistance between the stretchable substrate 30 and the stretchable wiring 40 can be further improved.

[0063] The first stretchable wiring 20 and / or the second stretchable wiring 40 and the via 50 may be made of the same material. In such a case, there may not be a visible boundary between the stretchable wiring and the via 50 made of the same material in a cross-sectional view. In other words, the stretchable wiring and the via 50 may be integrally formed (see FIG. 9B ). In such a structure, the boundary 51 a between the via 50 and the second stretchable wiring 40 and the boundary 51 b between the via 50 and the first stretchable wiring 20 can each be determined as follows.

[0064] For example, when the interface between the stretchable substrate 30 and the stretchable wirings 20, 40 is a uniform plane (i.e., when the stretchable substrate 30 does not have any unevenness such as convex portions 32), the boundaries 51a, 51b between the stretchable wirings 20, 40 and the via 50 can be regarded as virtual planes extending the interface between the stretchable substrate 30 and the stretchable wirings 20, 40 in the area where the via 50 does not exist.

[0065] On the other hand, when the stretchable substrate 30 has protrusions 32 on both sides of the via 50, the boundary 51a between the via 50 and the second stretchable wiring 40 can be determined based on the position in the thickness direction Z of the stretchable substrate 30. For example, as shown in Fig. 9B, when the stretchable substrate 30 has protrusions 32 on both sides of the via 50, the boundary 51a between the via 50 and the second stretchable wiring 40 can correspond to an imaginary line connecting the vertex (or the center of the top surface 32a) of one protrusion 32 and the center (or vertex 321) of the top surface 32a of the other protrusion 32 located on the opposite side with the via 50 in between. This means that, in the thickness direction Z, when the side where the second elastic wire 40 is located is considered to be the upper direction and the side where the first elastic wire 20 is located is considered to be the lower direction, an imaginary line connecting the point where the main surface 30a of the elastic substrate 30 on one side of the via 50 is located at the uppermost position and the point where the main surface 30a of the elastic substrate 30 on the other side of the via 50 is located at the uppermost position corresponds to the boundary 51a. Note that, although FIG. 9B shows an example in which the boundary 51a extends parallel to the main surface 20a of the first elastic wire (for example, the X-Y plane), the boundary 51a does not necessarily have to be parallel to the X-Y plane. For example, the boundary 51a may extend in a direction intersecting the extension direction of the X-Y plane.

[0066] Similarly, when the first stretchable substrate 10 has convex portions 12 on both sides of the via 50, and the first stretchable wire 20 has a portion that slopes toward the via 50 (see FIG. 9C ), the boundary 51b between the via 50 and the first stretchable wire 20 can be determined based on the position of the first stretchable wire 20 in the thickness direction Z. Specifically, with respect to the thickness direction Z, when the side on which the second stretchable wire 40 is located is considered to be the upper direction and the side on which the first stretchable wire 20 is located is considered to be the lower direction, an imaginary line connecting the point on which the main surface 20a of the first stretchable wire 20 on one side of the via 50 is located at the uppermost position and the point on which the main surface 20a of the first stretchable wire 20 on the other side of the via 50 is located at the uppermost position corresponds to the boundary 51b. Note that, although FIG. 9B shows an example in which the boundary 51b extends parallel to the main surface 40a of the second stretchable wire (for example, the X-Y plane), the boundary 51b does not necessarily have to be parallel to the X-Y plane. For example, the boundary 51b may extend in a direction intersecting the extension direction of the XY plane.

[0067] 10 , in a region that does not overlap with the via 50 when viewed from the stacking direction Z, the thickness dimension of the second elastic wire 40 may change gradually toward the convex portion 32. More specifically, the thickness dimension of the second elastic wire 40 may gradually increase toward the convex portion 32 in a region located on the opposite side of the via 50 with the convex portion 32 interposed therebetween. This structure can also be interpreted as a structure in which the second elastic wire 40 has a convex portion 46 that bites into the second elastic substrate 30 in a portion adjacent to the convex portion 32 in a cross-sectional view. In other words, the second elastic substrate 30 has a concave portion 36 adjacent to the convex portion 32 on the opposite side of the via 50 with the convex portion 32 interposed therebetween, and the concave portion and the convex portion 46 of the second elastic wire 40 may have a complementary shape.

[0068] As a result, the second stretchable substrate 30 and the second stretchable wiring 40 are closely fitted together by meshing with each other due to the unevenness formed around the via 50, and the anchor effect acting between the substrate 30 and the wiring 40 can be made stronger. Furthermore, since the thickness of the stretchable wiring 20 changes gradually towards the via 50, a sudden change in stretchability in the region including the via 50 can be suppressed, and local stress concentration can be reduced. As described above, a stretchable device in which the peel resistance between the second stretchable substrate 30 and the second stretchable wiring 40 is further improved can be provided.

[0069] [Third Embodiment] FIG. 11 is a cross-sectional view schematically illustrating a stretchable device 1M according to the third embodiment, which is a combination of the first and second embodiments. The stretchable device 1M may have both the feature of the first stretchable substrate 10 having the convex portion 12 described in the first embodiment and the feature of the second stretchable substrate 30 having the convex portion 32. That is, in the stretchable device 1M, each of the stretchable substrates 10, 30 supporting the plurality of stretchable wirings 20, 40 connected by the vias 50 may have the above-described convex portion 12, 32. This allows each of the stretchable substrates 10, 30 to be suitably adhered to the stretchable wirings 20, 40 due to the anchor effect exerted by the convex portions 12, 32. In other words, peeling between the stretchable substrate and the stretchable wiring near the vias is suppressed, and the reliability of the electrical connection between the wirings via the vias can be improved. Therefore, a stretchable device with a more suitable via structure can be provided.

[0070] The convex portions 12 of the first stretchable substrate 10 and the convex portions 32 of the second stretchable substrate 30 may be offset from each other when viewed from the stacking direction Z. The convex portions 12 of the first stretchable substrate 10 and the convex portions 32 of the second stretchable substrate 30 do not need to be positioned so as to completely overlap each other when viewed from the stacking direction Z, but may be positioned so as to be offset from each other in the extension direction of the stretchable device. More specifically, the positions of the apex 121 of the convex portion 12 and the apex 321 (or the center of the top surface) of the convex portion 32 may be different from each other when viewed from the stacking direction Z. For example, the convex portions 12 and the convex portions 32 may be positioned so as to have a partially overlapping region but are offset from each other when viewed from the stacking direction Z. In other words, the stretchable device may have an overlapping region where the convex portions 12 and the convex portions 32 overlap each other and a non-overlapping region where they do not overlap. Alternatively, the convex portions 12 and the convex portions 32 may be positioned so as to not have an overlapping region and are offset from each other when viewed from the stacking direction Z.

[0071] For example, when the protrusions 12 and 32 are positioned so as to completely overlap each other in the stacking direction Z, the total thickness of the stretchable substrates 10, 30 increases sharply near the apexes of the protrusions 12 / 32. On the other hand, when the protrusions 12 and 32 are positioned so as to be offset from each other when viewed from the stacking direction Z, the abundance ratio of the stretchable substrates 10, 30 and the stretchable wirings 20, 40 in the stacking direction Z can change more gradually along the extension direction of the stretchable device (for example, direction X in FIG. 11 ). Therefore, when emphasis is placed on reducing fluctuations in the stretchability of the stretchable device as a whole, it is more preferable that the protrusions 12 and 32 are positioned so as to be offset from each other when viewed from the stacking direction Z.

[0072] [Fourth embodiment] Next, a stretchable device according to a fourth embodiment will be described. Fig. 12 is a schematic cross-sectional view of a stretchable device 1N according to a fourth embodiment of the present disclosure. The stretchable device according to the fourth embodiment differs from the stretchable device according to the first embodiment in that it includes a protective layer that covers the stretchable wiring exposed on the outer surface of the laminate.

[0073] 12 , the stretchable device 1N may further include a protective layer 60 that covers the second stretchable wiring 40 that is not sandwiched between the stretchable substrates 10, 30. Specifically, the stretchable device of the present disclosure includes a protective layer 60 positioned as the outermost layer, and the protective layer 60 may cover the second stretchable wiring 40 that is not sandwiched between the stretchable substrates 10, 30, among the multiple stretchable wirings 20, 40. The second stretchable wiring 40 may be covered by the protective layer 60 on the main surface 40a located opposite the second stretchable substrate 30. In other words, the second stretchable wiring 40 may be surrounded by the second stretchable substrate 30 and the protective layer 60. In such a structure, the second stretchable substrate 30 may be adhered to the protective layer 60 in an area of ​​the main surface 30a of the second stretchable substrate 30 where the second stretchable wiring 40 is not disposed. In short, the protective layer 60 may be adhered to the second stretchable substrate 30 around the periphery of the second stretchable wiring 40 .

[0074] The protective layer 60 can suitably protect the second elastic wiring 40 from the outside. For example, the protective layer 60 can suitably prevent short circuits or damage caused by water droplets or foreign matter adhering to the elastic wiring 40. Furthermore, the protective layer 60 functions as a barrier layer that protects the elastic wiring 40 from external air and / or humid air, thereby making it possible to prevent oxidation and corrosion of the elastic wiring 40.

[0075] The protective layer 60 may be made of a resin material having elasticity. The protective layer 60 may be made of the same material as the stretchable substrates 10, 30, or a different material may be used. If emphasis is placed on ensuring that the stretchable device has more uniform stretchability as a whole, the protective layer 60 is preferably made of the same material as the stretchable substrates 10, 30. This can suitably prevent peeling of the protective layer 60 due to differences in stretchability. On the other hand, if emphasis is placed on suitably protecting the stretchable wiring 40 from humid air, the protective layer 60 may be made of a material with a lower water absorption rate than the stretchable substrate 10. Even in such a case, from the viewpoint of the peel resistance of the protective layer 60, it is more preferable that the protective layer 60 be made of a material having elasticity similar to that of the stretchable substrates 10, 30.

[0076] Examples of materials used for the protective layer 60 include at least one selected from the group consisting of silicone-based resins, acrylic-based resins, olefin-based resins, modified urethane-based resins, styrene-based resins, vinyl chloride-based resins, polyester-based resins, polyamide-based resins, polyolefin-based resins, polyethylene-based resins, and polypropylene-based resins.

[0077] Fifth Embodiment Next, a stretchable device according to a fifth embodiment will be described. Fig. 13 is a schematic plan view of a stretchable device 1P according to a fifth embodiment of the present disclosure. Fig. 14 is a schematic cross-sectional view showing the B-B cross section of the stretchable device 1P shown in Fig. 13. The stretchable device according to the fifth embodiment differs from the stretchable device according to the first embodiment in that the second stretchable substrate 30, through which the via 50 penetrates, is provided with an opening 70.

[0078] As shown in FIGS. 13 and 14 , the second stretchable substrate 30 through which the via 50 penetrates may have an opening 70 disposed adjacent to the stretchable wiring 20, 40 when viewed from the stacking direction Z. The opening 70 may be provided so as to penetrate the second stretchable substrate 30. Alternatively, the opening 70 may be a depression formed by partially reducing the thickness of the second stretchable substrate 30. In other words, the opening 70 does not necessarily have to penetrate the second stretchable substrate 30. Such an opening 70 may also be referred to as, for example, a "recess," "hole," or "void." The opening 70 provides a region in which the stretchable wiring 20, 40 is partially not in contact with the second stretchable substrate 30. The planar shape of the opening 70 is not particularly limited, and may be, for example, a quadrangle (e.g., square, rectangle, etc.), a polygon such as a triangle, a circle, an ellipse, a semicircle, a crescent, or an irregular shape.

[0079] In a structure including the opening 70, the via 50 may extend to a position adjacent to the opening 70. For example, the via 50 and the opening 70 may be arranged continuously. In such a structure, the via 50 may extend to reach at least a portion of the edge of the stretchable wiring 20, 40. The opening 70 may be arranged adjacent to the stretchable wiring 20, 40 and the via 50 when viewed from the stacking direction Z. In other words, the stretchable device may include an opening 70 arranged adjacent to the stretchable wiring 20, 40 and the via 50. With such an opening 70, the edge portions of the end faces 50a, 50b of the via 50 located on the opening 70 side are not in contact with the second stretchable substrate 30. Therefore, the stretchable device is less susceptible to the effects of stress concentration and the like that accompany stretching of the stretchable device. Furthermore, by reducing the contact area with the second stretchable substrate 30, the number of potential locations for delamination between the second stretchable substrate 30 and the via 50 is reduced, which may improve the delamination resistance of the second stretchable substrate 30 for the entire stretchable device.

[0080] 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.

[0081] For example, in a cross-sectional view, the second elastic wire 40 may have a curved structure that bends to follow the shape of the second elastic substrate 30. That is, in a cross-sectional view, the second elastic wire 40 may form the recesses 42 and the protrusions 46 of the second elastic wire 40 by bending to follow the protrusions 32 and / or the recesses 36 (see FIG. 10 ) of the second elastic substrate 30. In such a structure, the second elastic wire 40 may extend approximately uniformly without significant variation in thickness at the recesses 42 and the protrusions 46. That is, the second elastic wire 40 may have a curved structure that bends to follow the protrusions 32 and / or the recesses 36 of the second elastic substrate 30, while having a approximately uniform thickness.

[0082] It should be noted that one embodiment of the present disclosure as described above includes the following preferred aspects. <1> A stretchable device comprising a plurality of stretchable substrates stacked on one another, a plurality of stretchable wirings arranged on each of the plurality of stretchable substrates, and a via that electrically connects at least two of the stretchable wirings that overlap each other via the stretchable substrate when viewed in the stacking direction of the stretchable substrates, wherein, in a cross-sectional view, at least one of the plurality of stretchable substrates, on which the stretchable wiring connected to the via is arranged, comprises a convex portion that protrudes around the via toward the stretchable wiring side. <2> The stretchable device according to <1>, wherein the via does not penetrate the stretchable substrate comprising the convex portion. <3> The stretchable device according to <1> or <2>, wherein the stretchable substrate comprising the convex portion is interposed between the plurality of stretchable wirings that are connected to each other via the via. <4> The stretchable device according to <3>, wherein, in a cross-sectional view, the convex portion is adjacent to the via. <5> The stretchable device according to any one of <1> to <4>, wherein the stretchable wire formed on the convex portion comprises a curved portion that bends following the outer contour of the convex portion in a cross-sectional view. <6> The stretchable device according to any one of <1> to <5>, wherein the stretchable wire formed on the convex portion comprises a curved portion that bends following the outer contour of the convex portion in a cross-sectional view. <7> The stretchable device according to any one of <1> to <6>, wherein the stretchable wire arranged on the stretchable substrate comprising the convex portion comprises a relatively recessed recess on a main surface facing the convex portion, and the convex portion protrudes towards the recessed recess. <8> The stretchable device according to <7>, wherein the thickness dimension of the stretchable wire at the recessed portion gradually decreases towards the via. <9> The stretchable device according to <7>, wherein the thickness dimension of the stretchable wire gradually decreases from the recess in a direction away from the via. <10> The stretchable device according to any one of <1> to <9>, wherein the via has a tapered shape that gradually tapers along the stacking direction in a cross-sectional view. <11> The stretchable device according to any one of <1> to <10>, wherein the convex portion is positioned along the periphery of the via when viewed from the stacking direction.<12> The stretchable device according to any one of <1> to <11>, wherein, in a cross-sectional view, the convex portion has a polygonal shape having at least three or more faces. <13> The stretchable device according to <12>, wherein, in a cross-sectional view, the convex portion has a top surface located at a tip of the convex portion, and a width dimension of the top surface is 1% to 100% of a maximum width dimension of the via. <14> The stretchable device according to any one of <1> to <13>, wherein, among the plurality of stretchable substrates, a stretchable substrate not penetrated by the via has a thickness dimension in an overlapping region overlapping with the via that is larger than a region other than the overlapping region. <15> The stretchable device according to any one of <1> to <14>, wherein a thickness dimension of the stretchable substrate gradually increases with increasing distance from the convex portion. <16> The stretchable device according to any one of <1> to <15>, further comprising a protective layer that covers the stretchable wiring arranged on the stretchable substrate located at the outermost layer among the plurality of stretchable substrates stacked on each other. <17> The stretchable device according to <16>, wherein the stretchable substrate and the protective layer are made of the same material. <18> The stretchable device according to any one of <1> to <17>, wherein the stretchable substrate through which the via penetrates has an opening adjacent to the stretchable wiring when viewed from the stacking direction, and the via is continuous with the opening when viewed from the stacking direction.

[0083] The above effects are merely exemplary, and the present disclosure is not limited to the above, and additional effects may also be provided.

[0084] 1A to 1P: Stretchable device 10: First stretchable substrate 12: Convex portion of first stretchable substrate 20: First stretchable wiring 22: Concave portion of first stretchable wiring 24: Curved portion 30: Second stretchable substrate 32: Convex portion of second stretchable substrate 36: Concave portion of second stretchable substrate 40: Second stretchable wiring 42: Concave portion of second stretchable wiring 46: Convex portion of second stretchable wiring 50: Via 60: Protective layer 70: Opening

Claims

1. A stretchable device comprising: a plurality of stretchable substrates stacked on top of one another; a plurality of stretchable wirings arranged on each of the plurality of stretchable substrates; and vias that electrically connect at least two of the stretchable wirings that overlap each other via the stretchable substrates when viewed from the stacking direction of the stretchable substrates; wherein, in a cross-sectional view, at least one of the plurality of stretchable substrates, on which the stretchable wirings connected to the vias are arranged, has a protrusion that protrudes around the via toward the stretchable wiring side.

2. The stretchable device of claim 1, wherein the vias do not penetrate the stretchable substrate comprising the protrusions.

3. The stretchable device according to claim 1 or 2, wherein the stretchable substrate having the convex portion is interposed between the plurality of stretchable wirings connected to each other through the vias.

4. The stretchable device according to claim 3, wherein the protrusion is adjacent to the via in cross-sectional view.

5. A stretchable device according to any one of claims 1 to 4, wherein the stretchable wiring formed on the convex portion has a curved portion that bends to follow the outer contour of the convex portion in a cross-sectional view.

6. The stretchable device according to any one of claims 1 to 5, wherein, in a cross-sectional view, the distance between at least two of the stretchable wirings connected by the vias comprises a portion where the distance gradually decreases toward the vias.

7. The stretchable device according to any one of claims 1 to 6, wherein the stretchable wiring arranged on the stretchable substrate having the convex portions has relatively recessed portions on a main surface facing the convex portions, and the convex portions are raised toward the recessed portions.

8. The stretchable device according to claim 7, wherein the thickness dimension of the stretchable wiring in the recessed portion gradually decreases toward the via.

9. The stretchable device according to claim 7, wherein the thickness dimension of the stretchable wiring gradually decreases from the recess in a direction away from the via.

10. The stretchable device according to any one of claims 1 to 9, wherein, in a cross-sectional view, the via has a tapered shape that gradually narrows along the stacking direction.

11. The stretchable device according to any one of claims 1 to 10, wherein the protrusions are positioned along the periphery of the vias when viewed from the stacking direction.

12. The stretchable device according to any one of claims 1 to 11, wherein, in cross section, the convex portion has a polygonal shape having at least three or more faces.

13. The stretchable device according to claim 12, wherein, in a cross-sectional view, the convex portion has a top surface located at a tip of the convex portion, and the width dimension of the top surface is 1% or more and 100% or less of the maximum width dimension of the via.

14. The stretchable device according to any one of claims 1 to 13, wherein, of the plurality of stretchable substrates, the stretchable substrates not penetrated by the vias have a thickness dimension in an overlapping region overlapping with the vias that is greater than a thickness dimension in a region other than the overlapping region.

15. The stretchable device according to any one of claims 1 to 14, wherein the thickness dimension of the stretchable substrate gradually increases with increasing distance from the protrusions.

16. The stretchable device according to any one of claims 1 to 15, further comprising a protective layer that covers the stretchable wiring arranged on the stretchable substrate located on the outermost layer of the plurality of stretchable substrates stacked on one another.

17. The stretchable device of claim 16, wherein the stretchable substrate and the protective layer are composed of the same material.

18. The stretchable device according to any one of claims 1 to 17, wherein the stretchable substrate through which the via penetrates has an opening adjacent to the stretchable wiring when viewed from the stacking direction, and the via is continuous with the opening when viewed from the stacking direction.

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