Stretchable device

Abstract

This stretchable device comprises: a stretchable first base material; first wiring provided on a first primary surface of the first base material; a second base material which faces the first base material in a first direction which is the thickness direction of the first base material and is connected to the first base material;　second wiring which is provided on a first primary surface of the second base material and faces the first wiring in the first direction; and　a first protective layer which is continuously provided on the first primary surface of the first base material and a second primary surface of the second base material so as to cover at least a portion of the first wiring and a portion of the second base material, wherein the first wiring and the second wiring are electrically connected in an overlap region where the wirings overlap each other when viewed in the first direction, and the first protective layer overlaps the entirety of the overlap region when viewed in the first direction.

Description

stretchable devices

[0001] The present disclosure relates to stretchable devices.

[0002] A conventional stretchable device is described in Japanese Patent Laid-Open No. 2008-108890 (Patent Document 1). This stretchable device includes a first substrate, a first wiring provided on a first main surface of the first substrate, a second substrate facing the first substrate in the thickness direction of the first substrate, a second wiring provided on the second substrate facing the first wiring in the thickness direction, and a connecting member connecting the first substrate and the second substrate. The first wiring and the second wiring are electrically connected.

[0003] JP 2008-108890 A

[0004] However, in the conventional stretchable device, if the wiring is exposed to the outside, water droplets or foreign matter may adhere across adjacent wiring, causing a short circuit between the adjacent wiring and damaging the stretchable device. Furthermore, exposure of the metal wiring to air or moisture may cause oxidation or corrosion of the wiring. Therefore, it is considered to cover the surface of the wiring with a protective layer. Specifically, the protective layer is provided only on all portions of the first wiring that are exposed from the second substrate.

[0005] However, it has been found that when an external force acts on a portion of the first substrate that is separated from a wiring connection portion, which is a connection portion between the first wiring and the second wiring, as viewed from a direction perpendicular to the first main surface of the first substrate, for example, in a direction perpendicular to the extension direction of the first wiring and parallel to the first main surface of the first substrate, or in a direction perpendicular to the first main surface of the first substrate, peeling may occur between the first wiring and the second wiring. In other words, it has been found that the strength of the wiring connection portion in the conventional stretchable device is insufficient.

[0006] Therefore, an object of the present disclosure is to provide a stretchable device that can ensure the strength of wiring connections.

[0007] In order to solve the above problem, a stretchable device according to one aspect of the present disclosure comprises: a first substrate having stretchability; a first wiring provided on a first main surface of the first substrate; a second substrate facing the first substrate in a first direction that is a thickness direction of the first substrate and connected to the first substrate; a second wiring provided on the first main surface of the second substrate and facing the first wiring in the first direction; and a first protective layer provided continuously on the first main surface of the first substrate and on a second main surface of the second substrate so as to cover at least a portion of the first wiring and at least a portion of the second substrate, wherein the first wiring and the second wiring are electrically connected in an overlapping region where they overlap each other when viewed from the first direction, and the first protective layer overlaps the entire overlapping region when viewed from the first direction.

[0008] According to the stretchable device of one aspect of the present disclosure, it is possible to suppress a decrease in strength of the wiring connection portion.

[0009] FIG. 1 is a partially enlarged top view schematically showing a stretchable device according to a first embodiment of the present disclosure. FIG. 2 is an exploded plan view schematically showing a stretchable device according to the first embodiment of the present disclosure. FIG. 3 is a cross-sectional view taken along III-III in FIG. 1. FIG. 4 is a partial cross-sectional view of a stretchable device according to a second embodiment of the present disclosure. FIG. 5 is a partial cross-sectional view of a stretchable device according to a third embodiment of the present disclosure. FIG. 6 is a partial cross-sectional view of a stretchable device according to a fourth embodiment of the present disclosure. FIG. 7 is a partial cross-sectional view of a stretchable device according to a fifth embodiment of the present disclosure. FIG. 8 is a partial cross-sectional view of a stretchable device according to a sixth embodiment of the present disclosure. FIG. 9 is a partial cross-sectional view of a stretchable device according to a seventh embodiment of the present disclosure.

[0010] 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.

[0011] [First Embodiment] The structure of a stretchable device 100 according to a first embodiment will be described with reference to FIGS. 1, 2, and 3. FIG. 1 is a partial top view of the stretchable device 100. FIG. 2 is an exploded plan view of the stretchable device 100. FIG. 3 is a cross-sectional view of the stretchable device 100 taken along the line III-III in FIG. 1. Note that cross-sectional views in this specification are cross-sectional views parallel to the first direction, which is the thickness direction of the first substrate, including overlapping regions (i.e., wiring connection portions) where the first wiring 2 and the second wiring 4 overlap each other. The first direction is indicated by a double-arrow X. The thickness direction of the first substrate 1, the thickness direction of the second substrate 3, and the first direction X coincide with each other. Furthermore, in FIG. 1, for convenience, the first protective layer 6 is indicated by a two-dot chain line, and the first protective layer 6 is depicted as being transparent, but the first protective layer 6 does not have to be transparent.

[0012] The stretchable device 100 includes a first substrate 1, a second substrate 3, a first wiring 2, a second wiring 4, and a first protective layer 6. The first substrate 1 and the second substrate 3 are connected to each other. The first wiring 2 provided on the first main surface 1a of the first substrate 1 and the second wiring 4 provided on the first main surface 3a of the second substrate 3 are electrically connected to each other in an overlapping region Z1 where they overlap when viewed from the first direction X. The first protective layer 6 is provided continuously on the first main surface 1a of the first substrate 1 and on the second main surface 3b of the second substrate 3 so as to cover at least a portion of the first wiring 2 and at least a portion of the second substrate 3.

[0013] The shape of the stretchable device 100 is not particularly limited. In this specification, a structure in which two substrates are connected is described as an example, but three or more substrates may be connected. Furthermore, the arrangement of the first wiring 2 is not limited to that shown in FIG. 1 , and the extension direction is also not limited. Specifically, the longitudinal direction of the first substrate 1 and the extension direction of the first wiring 2 do not have to coincide, and the first wiring 2 does not have to extend in one direction. Furthermore, the number of first wirings 2 is not particularly limited, and may be one or more. When there are multiple first wirings 2, they may include wirings that are not electrically connected to the second wirings 4. The same applies to the arrangement and number of second wirings 4.

[0014] Furthermore, "above" in this specification does not have to coincide with the up and down when the stretchable device 100 is in use. More specifically, "on the main surface of the first substrate 1" does not refer to an absolute direction such as vertically upward as defined by the direction of gravity, but rather refers to a direction toward the outside of the outside and inside with the main surface of the first substrate 1 as a boundary. The same applies to "on the main surface of the second substrate 3." Furthermore, "above" with respect to an element includes not only an above position separated from the element, i.e., an above position via another object on the element or an above position spaced apart, but also a position directly above the element (on).

[0015] These components and their arrangement will be described below. As shown in Figures 1, 2, and 3, the first substrate 1 and the second substrate 3 face each other in the first direction X and partially overlap each other when viewed from the first direction X. Similarly, the first wiring 2 and the second wiring 4 face each other in the first direction X.

[0016] The first substrate 1 has stretchability. When the first substrate 1 has stretchability, the stretching of the first wiring 2 is not inhibited, and the risk of breakage due to stretching during use of the stretchable device 100 can be reduced.

[0017] Examples of stretchable substrates include sheet- or film-shaped substrates made of stretchable resin materials. The resin material preferably contains at least one resin selected from the group consisting of acrylic resins, styrene resins, and urethane resins. Examples of urethane resins include thermoplastic polyurethanes. The thickness of the first substrate 1 is not particularly limited, but from the viewpoint of not inhibiting the stretching of the surface of the living body when attached to the living body, it is preferably 1 mm or less, more preferably 100 μm or less, and even more preferably 50 μm or less. Furthermore, the thickness of the first substrate 1 is more preferably 1 μm or more. The first substrate 1 has a first main surface 1a and a second main surface 1b located on opposite sides of each other.

[0018] The first wiring 2 is provided on the first main surface 1a of the first substrate 1. The first wiring 2 is preferably stretchable. Examples of materials for the first wiring 2 include a mixture of conductive particles, such as metal powders of Ag, Cu, or Ni, and an elastomer resin, such as a silicone resin. The average particle size of the conductive particles is not particularly limited, but is preferably 0.01 μm or more and 10 μm or less. The conductive particles are preferably spherical, but may also be flat or have protrusions to improve stretchability. The elastomer resin preferably includes at least one resin (elastomer resin) selected from the group consisting of epoxy resins, urethane resins, acrylic resins, and silicone resins, which is preferable for ensuring stretchability.

[0019] The first wiring 2 has a first end 21 and a second end 22. The first end 21 is the end on the overlap region Z1 side of both ends in the extension direction. In other words, the first end 21 is the end that overlaps with the second wiring 4 when viewed from the first direction X. The second end 22 is the end on the opposite side of the first end 21 with respect to the center of the first wiring 2 in the extension direction.

[0020] The thickness of the first wiring 2 is preferably 100 μm or less, more preferably 50 μm or less. The thickness of the stretchable wiring is more preferably 1 μm or more. The thickness, width, and length of the first wiring 2 are not particularly limited. The first wiring 2 does not have to be stretchable.

[0021] A method for forming the first wiring 2 on the first substrate 1 will now be described. When the material of the first wiring 2 is, for example, a conductive paste containing a mixture of Ag and resin, the conductive paste is applied to the first substrate 1. The application method may be screen printing, gravure printing, or inkjet printing. The conductive paste is then thermally cured to obtain a predetermined resistance value, thereby forming the first wiring 2 on the first substrate 1.

[0022] The second substrate 3 is preferably elastic. The second substrate 3 preferably has a larger Young's modulus than the first wiring 2. Specific examples include substrates such as FPCs (Flexible Printed Circuits), FFCs (Flexible Flat Cables), and PCBs (Printed Circuit Boards). By making the Young's modulus larger than that of the first wiring 2, pressure can be more easily applied to the joint during crimping, enabling bonding with low pressure. In other words, lowering the pressure can reduce damage to the substrates during bonding. Furthermore, the second substrate 3 preferably has a larger Young's modulus than the first substrate 1. This increases resistance to impacts during connection, thereby further improving connection reliability. The second substrate 3 has a first main surface 3a and a second main surface 3b located on opposite sides of each other.

[0023] The second substrate 3 is connected to the first substrate 1. That is, the first main surface 1a of the first substrate 1 and the first main surface 3a of the second substrate 3 are directly connected by welding or the like. Specifically, the first main surface 1a of the first substrate 1 and the first main surface 3a of the second substrate 3 are thermocompression bonded. Note that the first substrate 1 and the second substrate 3 may be connected via an adhesive member such as a thermoplastic adhesive, for example.

[0024] The second substrate 3 does not have to be stretchable. Examples of the second substrate 3 include sheet- or film-shaped substrates such as polyethylene terephthalate (PET) and polyimide, and substrates such as FPC, FFC, and PCB. The second substrate 3 may also be the same as the first substrate 1.

[0025] The second wiring 4 is provided on the first main surface 3a of the second substrate 3. The second wiring 4 is preferably stretchable. The second wiring 4 is preferably a wiring having a larger Young's modulus than the first wiring 2. For example, a metal wiring such as copper foil can be used. The thickness of the second wiring 4 is preferably 1 μm or more and 100 μm or less, more preferably 50 μm or less. In this embodiment, the first wiring 2 and the second wiring 4 are in direct contact and electrically connected in the overlapping region Z1. The overlapping region Z1 is a region where the first wiring 2 and the second wiring 4 overlap each other when viewed from the first direction X, and is a region where the first wiring 2 and the second wiring 4 can be electrically connected. The first wiring 2 and the second wiring 4 are in direct contact throughout the entire overlapping region Z1, but this is not limited thereto; they may be in direct contact only in a portion of the overlapping region Z1. The second wiring 4 does not have to be stretchable. The second wiring 4 may also be the same as the first wiring 2.

[0026] The second wiring 4 has a first end 41 and a second end 42. The first end 41 is the end on the overlap region Z1 side of both ends in the extension direction. In other words, the first end 41 is the end that overlaps with the first wiring 2 when viewed from the first direction X. The second end 42 is the end on the opposite side of the overlap region Z1 (first end 41) with respect to the center of the extension direction of the second wiring 4.

[0027] The second wiring 4 is electrically connected to the first wiring 2. Specifically, the first wiring 2 and the second wiring 4 are in contact with each other and electrically connected. Note that the first wiring 2 and the second wiring 4 may be electrically connected via a conductive connecting member.

[0028] The first protective layer 6 is provided continuously on the first main surface 1 a of the first substrate 1 and the second main surface 3 b of the second substrate 3 so as to cover at least a portion of the first wiring 2 and at least a portion of the second substrate 3. The first protective layer 6 overlaps the entire overlap region Z1 when viewed from the first direction X. In other words, the first protective layer 6 covers the entire overlap region Z1. Because the first protective layer 6 covers at least a portion of the first wiring 2, even if water droplets or foreign matter adhere across the gap between adjacent first wirings 2, it is possible to suppress short-circuiting between adjacent first wirings 2, and also to reduce exposure of the first wiring 2 to air and moisture, thereby suppressing oxidation and corrosion of the first wiring 2.

[0029] Specifically, the first protective layer 6 covers the entire outer surface of the first wiring 2 except for the overlap region Z1. More specifically, the first protective layer 6 is in contact with the entire outer surface of the first wiring 2 except for the overlap region Z1 (hereinafter, the portion of the first protective layer 6 in contact with the entire outer surface will be referred to as the "first portion"). In other words, the first protective layer 6 is in contact with the entire outer surface of the first wiring 2 that is exposed from the first substrate 1, the second substrate 3, and the second wiring 4. Note that the first protective layer 6 may cover only a portion of the outer surface of the first wiring 2 except for the overlap region Z1. For example, the first protective layer 6 may cover the first wiring 2 so that the second end 22 of the first wiring 2 is exposed.

[0030] Furthermore, the first protective layer 6 covers at least the end portion of the second main surface 3b of the second substrate 3 on the overlapping region Z1 side. More specifically, the first protective layer 6 is in contact with at least the end portion of the second main surface 3b of the second substrate 3 on the overlapping region Z1 side (hereinafter, the portion of the first protective layer 6 in contact with the end portion on the overlapping region Z1 side will be referred to as the "second portion"). This end portion overlaps the entire overlapping region Z1 when viewed from the first direction X. As a result, the first protective layer 6 overlaps the entire overlapping region Z1 when viewed from the first direction X.

[0031] The first protective layer 6 also covers the side surface of the second substrate 3 on the overlapping region Z1 side and the side surface (first end 41) of the second wiring 4 on the overlapping region Z1 side (hereinafter, this covering portion of the first protective layer 6 will be referred to as the "third portion"). More specifically, the first protective layer 6 is in contact with the side surface of the second substrate 3 on the overlapping region Z1 side, and has a gap between it and the side surface (first end 41) of the second wiring 4 on the overlapping region Z1 side. The first protective layer 6 may also be in contact with the first end 41 of the second wiring 4.

[0032] The first portion, the third portion, and the second portion are continuous in this order. In other words, the first protective layer 6 covers the entire first wiring 2 including the overlapping region Z1, and also covers at least a portion of the second wiring 4. As a result, the first protective layer 6 covers not only the portions of the outer surface of the first wiring 2 that are exposed from the first substrate 1, the second substrate 3, and the second wiring 4, but also the entire overlapping region Z1.

[0033] Specific examples of the first protective layer 6 include a resin material or a mixture of a resin material and an inorganic material. Examples of resin materials include urethane-based, styrene-based, olefin-based, silicone-based, fluorine-based, nitrile rubber, latex rubber, vinyl chloride, ester-based, amide-based, and other elastomer-based resins, as well as epoxy, phenolic, acrylic, polyester, imide-based, rosin, cellulose, polyethylene terephthalate-based, polyethylene naphthalate-based, and polycarbonate-based resins. The first protective layer 6 is preferably insulating. Having insulating properties in the first protective layer 6 can more reliably suppress ion migration of the first wiring 2. The first protective layer 6 is formed, for example, by applying an insulating material or attaching a laminate material.

[0034] The thickness of the first protective layer 6 is preferably 1 μm or more and 100 μm or less, and more preferably 50 μm or less. By making the thickness of the first protective layer 6 1 μm or more, the durability of the first protective layer 6 can be ensured. Furthermore, by making the thickness of the first protective layer 6 100 μm or less, the overall height can be reduced. Note that when the thickness of the first protective layer 6 is not constant, the maximum dimension of the first protective layer 6 in the first direction X is taken as the thickness.

[0035] The first protective layer 6 also has a first protective layer end 61. The first protective layer end 61 is an end that overlaps with the second substrate 3 when viewed from the first direction X. Specifically, it is an end that overlaps with the second substrate 3 among both ends in the up-down direction in Fig. 1 , and an end that overlaps with the second substrate 3 among both ends in the left-right direction in Fig. 3 .

[0036] According to the stretchable device 100, the first protective layer 6 overlaps the entire overlap region Z1 when viewed from the first direction X. Therefore, the stretchability of the first substrate 1 can be reduced in the overlap region Z1 compared to conventional techniques in which a protective layer is not provided, thereby increasing the rigidity of the stretchable device 100. As a result, even when an external force acts on a portion of the first substrate 1 away from the overlap region Z1 (i.e., the wiring connection portion) as a fulcrum when viewed from a direction perpendicular to the first main surface 1 a of the first substrate 1 (first direction X), for example, in a direction perpendicular to the extension direction of the first wiring 2 and parallel to the first main surface 1 a of the first substrate 1 (the left-right direction in FIG. 1 ), or in a direction perpendicular to the first main surface 1 a of the first substrate 1, peeling between the first wiring 2 and the second wiring 4 can be suppressed, and the strength of the overlap region Z1 can be ensured.

[0037] In contrast, in the conventional technology in which the first protective layer covers only the exposed portion of the first wiring and does not cover the overlapping region between the first wiring and the second wiring, when an external force acts in the above direction on a portion of the first substrate 1 that is spaced from the overlapping region as a fulcrum, there is a risk of peeling between the first wiring and the second wiring. Furthermore, when the first protective layer 6 covers only a portion of the overlapping region Z1 as viewed from the first direction X, when an external force acts in the above direction on a portion of the first substrate 1 that is spaced from the overlapping region Z1 as a fulcrum, there is a risk of peeling between the first wiring 2 and the second wiring 4, and the strength of the overlapping region Z1 may be insufficient.

[0038] Furthermore, according to the stretchable device 100, the rigidity of the stretchable device 100 can be increased in the overlap region Z1, so that even if the second substrate 3 is pulled in the extension direction of the second wiring 4, for example, cracking of the second substrate 3 can be suppressed.

[0039] 1 , the first protective layer 6 preferably covers the entire first wiring 2. In other words, the first protective layer 6 overlaps the entire first wiring 2 when viewed from the first direction X. With this configuration, even if water droplets or foreign matter adhere across the gap between adjacent first wirings 2, it is possible to more reliably prevent short circuits between the adjacent first wirings 2, and it is also possible to more reliably reduce exposure of the first wirings 2 to air and moisture, thereby more reliably preventing oxidation and corrosion of the first wirings 2.

[0040] Preferably, as shown in FIG. 3 , the second wiring 4 has a first non-overlapping region Z2 that does not overlap with the first wiring 2 when viewed from the first direction X. The first protective layer 6 overlaps the entire first non-overlapping region Z2 when viewed from the first direction X. When viewed from the first direction X, a portion P1 of the first protective layer 6 that overlaps the first non-overlapping region Z2 and a portion P2 of the first protective layer 6 that overlaps the overlapping region Z1 are continuous. With this configuration, the first protective layer 6 overlaps the entire first non-overlapping region Z2 as well as the entire overlapping region Z1 when viewed from the first direction X. This ensures a more sufficient strength for the overlapping region Z1 than when the first protective layer 6 does not overlap the first non-overlapping region Z2. The first non-overlapping region Z2 corresponds to an example of a "non-overlapping region" as defined in the claims.

[0041] Next, the connection of the stretchable device 100 will be described. When connecting the first substrate 1 and the second substrate 3, the first substrate 1 and the second substrate 3 are thermocompression-bonded by applying heat and pressure. This connects the first substrate 1 and the second substrate 3. Note that there are no particular limitations on the method for compressing the first substrate 1 and the second substrate 3. Furthermore, the first wiring 2 and the second wiring 4 come into contact with each other and are electrically connected.

[0042] Second Embodiment Next, a second embodiment will be described with reference to Fig. 4. Fig. 4 is a partial cross-sectional view of a stretchable device 101 according to the second embodiment. The stretchable device 101 according to the second embodiment differs from the stretchable device 100 according to the first embodiment in that the size of the first protective layer 6 is different.

[0043] 4 , in the stretchable device 101 of the second embodiment, the second wiring 4 has a first non-overlapping region Z2 that does not overlap with the first wiring 2 when viewed from the first direction X. The first protective layer 6 overlaps a part of the first non-overlapping region Z2 when viewed from the first direction X. When viewed from the first direction X, a portion P1 of the first protective layer 6 that overlaps with the first non-overlapping region Z2 and a portion P2 of the first protective layer 6 that overlaps with the overlapping region Z1 are continuous.

[0044] Specifically, unlike the first embodiment, the first protective layer 6 does not cover the entire second wiring 4, but rather covers a portion of the second wiring 4 including the overlap region Z1. In other words, the first protective layer end 61 is located between the first end 21 of the first wiring 2 and the second end 42 of the second wiring 4 when viewed from the first direction X. In other words, the second base 3 has a region covered by the first protective layer 6 and a region exposed from the first protective layer 6.

[0045] According to the above configuration, a gradation of hardness can be formed in the stretchable device 101. Specifically, as shown in FIG. 4 , at a position corresponding to the above-mentioned portion P2 of the first protective layer 6, i.e., between the first end 41 of the second wiring 4 and the first end 21 of the first wiring 2, the stretchable device 101 has five layers stacked: a first substrate 1, a first wiring 2, a second wiring 4, a second substrate 3, and a first protective layer 6. At a position corresponding to the above-mentioned portion P1 of the first protective layer 6, i.e., between the first end 21 of the first wiring 2 and the first protective layer end 61, the stretchable device 101 has three layers stacked: a second wiring 4, a second substrate 3, and a first protective layer 6. Furthermore, between the first protective layer end 61 and the second end 42 of the second wiring 4, the stretchable device 101 has two layers stacked: a second wiring 4 and a second substrate 3. That is, from the first end 41 to the second end 42 of the second wiring 4, the number of laminated members decreases, and the hardness of the stretchable device 101 can be reduced in stages. This makes it possible to disperse stress that may occur in the second substrate 3 even when an external force is applied to the stretchable device 101. As a result, damage to the second substrate 3 can be suppressed.

[0046] Preferably, the length L1 of the portion P1 of the first protective layer 6 in the extension direction of the second wiring 4 is 50% or more, more preferably 100% or more of the length L2 of the portion P2 of the first protective layer 6 in the extension direction of the second wiring 4. According to this configuration, a gradation of hardness can be easily formed in the stretchable device 101, and damage to the second substrate 3 can be more reliably suppressed.

[0047] Preferably, the length L1 of the portion P1 of the first protective layer 6 in the extension direction of the second wiring 4 is 70% or less, more preferably 30% or less, of the value obtained by subtracting the length L2 from the length L3 in the extension direction of the second wiring 4. According to this configuration, a gradation of hardness can be easily formed in the stretchable device 101, and damage to the second substrate 3 can be more reliably suppressed.

[0048] [Third Embodiment] Next, a third embodiment will be described with reference to Fig. 5. Fig. 5 is a partial cross-sectional view of a stretchable device 102 according to the third embodiment. The stretchable device 102 according to the third embodiment differs from the stretchable device 100 according to the first embodiment in that a second protective layer is provided.

[0049] 5 , the stretchable device 102 of the third embodiment further includes a second protective layer 7. The material and thickness of the second protective layer 7 are preferably the same as the material and thickness of the first protective layer 6.

[0050] The second protective layer 7 is provided continuously on the first main surface 3a of the second substrate 3 and the second main surface 1b of the first substrate 1 so as to cover at least a portion of the second wiring 4 and at least a portion of the first substrate 1.

[0051] Specifically, the second protective layer 7 covers the entire outer surface of the second wiring 4 except for the overlap region Z1. More specifically, the second protective layer 7 is in contact with the entire outer surface of the second wiring 4 except for the overlap region Z1 (hereinafter, the portion of the second protective layer 7 in contact with the entire outer surface is referred to as the "fourth portion"). In other words, the second protective layer 7 is in contact with the entire outer surface of the second wiring 4 that is exposed from the first substrate 1, the second substrate 3, and the first wiring 2. Note that the second protective layer 7 may cover a portion of the outer surface of the second wiring 4 except for the overlap region Z1. For example, the second protective layer 7 may cover the second wiring 4 so that the second end 42 of the second wiring 4 is exposed.

[0052] Furthermore, the second protective layer 7 covers at least the end portion of the second main surface 1b of the first substrate 1 on the overlapping region Z1 side. More specifically, the second protective layer 7 is in contact with at least the end portion of the second main surface 1b of the first substrate 1 on the overlapping region Z1 side (hereinafter, the portion of the second protective layer 7 in contact with the end portion on the overlapping region Z1 side is referred to as the "fifth portion"). In this embodiment, this end portion overlaps the entire overlapping region Z1 when viewed from the first direction X. As a result, the second protective layer 7 overlaps the entire overlapping region Z1 when viewed from the first direction X. Note that the second protective layer 7 may overlap a portion of the overlapping region Z1 when viewed from the first direction X.

[0053] The second protective layer 7 also covers the side surface of the first substrate 1 on the overlapping region Z1 side and the side surface (first end 21) of the first wiring 2 on the overlapping region Z1 side (hereinafter, this covering portion of the second protective layer 7 will be referred to as the "sixth portion"). More specifically, the second protective layer 7 is in contact with the side surface of the first substrate 1 on the overlapping region Z1 side, and has a gap between it and the side surface (first end 21) of the first wiring 2 on the overlapping region Z1 side. The second protective layer 7 may also be in contact with the first end 21 of the first wiring 2.

[0054] The fourth portion, the sixth portion, and the fifth portion are continuous in this order. In other words, the second protective layer 7 covers the entire second wiring 4 including the overlapping region Z1, and also covers at least a part of the first wiring 2. As a result, the second protective layer 7 covers not only the portion of the outer surface of the second wiring 4 that is exposed from the first substrate 1, the second substrate 3, and the first wiring 2, but also the entire overlapping region Z1.

[0055] The second protective layer 7 also has a second protective layer end portion 71. The second protective layer end portion 71 is an end portion that overlaps with the first substrate 1 when viewed from the first direction X. Specifically, it is an end portion that overlaps with the first substrate 1, of both end portions in the left-right direction in FIG.

[0056] According to the above configuration, the second protective layer 7 covers at least a portion of the second wiring 4, so that even if water droplets or foreign matter adhere across the gap between adjacent second wirings 4, short circuits between adjacent second wirings 4 can be suppressed, and exposure of the second wiring 4 to air and moisture can be reduced, thereby suppressing the occurrence of oxidation and corrosion of the second wiring 4.

[0057] 5 , the first wiring 2 preferably has a second non-overlapping region Z3 that does not overlap with the second wiring 4 when viewed from the first direction X. The second protective layer 7 overlaps a portion of the second non-overlapping region Z3 when viewed from the first direction X. When viewed from the first direction X, a portion P3 of the second protective layer 7 that overlaps with the second non-overlapping region Z3 and a portion P4 of the second protective layer 7 that overlaps with the overlapping region Z1 are continuous.

[0058] Specifically, the second protective layer 7 covers a part of the first wiring 2, including the overlap region Z1. In other words, the second protective layer end 71 is located between the second end 22 of the first wiring 2 and the first end 41 of the second wiring 4, as viewed from the first direction X.

[0059] According to the above configuration, similar to the second embodiment, a gradation in hardness of the stretchable device 102 can be formed even on the side where the first wiring 2 is provided. That is, the number of laminated members decreases from the first end 21 to the second end 22 of the first wiring 2, and the hardness of the stretchable device 102 can be reduced in stages. This makes it possible to disperse stress that may occur in the first substrate 1 even when an external force is applied to the stretchable device 102. As a result, damage to the first substrate 1 can be suppressed.

[0060] The second protective layer 7 may cover the entire second main surface 1b of the first base material 1. This makes it possible to more reliably prevent moisture from entering from the second main surface 1b side of the first base material 1.

[0061] [Fourth embodiment] Next, a fourth embodiment will be described with reference to Fig. 6. Fig. 6 is a partial cross-sectional view of a stretchable device 103 according to the fourth embodiment. The stretchable device 103 according to the fourth embodiment differs from the stretchable device 100 according to the first embodiment in that a first insulating layer and a second insulating layer are provided.

[0062] 6 , the stretchable device 103 of the fourth embodiment further includes a first insulating layer 31 and a second insulating layer 32. The materials of the first insulating layer 31 and the second insulating layer 32 are different from the material of the first protective layer 6.

[0063] The first insulating layer 31 and the second insulating layer 32 preferably have a lower water absorption rate than the first substrate 1. Examples of materials for the first insulating layer 31 and the second insulating layer 32 include silicone-based resins, acrylic-based resins, olefin-based resins, modified urethane-based resins, vinyl chloride-based resins, polyester-based, polyamide-based, polyolefin-based, polyethylene-based, and polypropylene-based resin materials. The first insulating layer 31 and the second insulating layer 32 are formed, for example, by printing.

[0064] The first insulating layer 31 covers at least a portion of the exposed surface of the first wiring 2. The exposed surface of the first wiring 2 is the surface of the outer surface of the first wiring 2 that is exposed from the first substrate 1 and the second wiring 4. Specifically, the exposed surface of the first wiring 2 is the surface of the first wiring 2 that is not covered by the first substrate 1 and the second wiring 4. The first insulating layer 31 preferably covers the entire exposed surface of the first wiring 2, but may cover a portion of the exposed surface of the first wiring 2. The first insulating layer 31 is preferably present between the first wiring 2 and the first protective layer 6. The first insulating layer 31 does not overlap the second wiring 4 in the first direction X, but a portion of the first insulating layer 31 may overlap the second wiring 4 in the first direction X. According to the above configuration, the first insulating layer 31 prevents short-circuiting between adjacent first wirings 2 due to water droplets or foreign matter, improving reliability.

[0065] Here, the method of forming the first insulating layer 31 will be described. An insulating paste, which is the material of the first insulating layer 31, is printed on the first wiring 2 by screen printing or the like. At this time, in a cross section perpendicular to the extension direction of the first wiring 2, the insulating paste is preferably printed to a size larger than the width of the first wiring 2 by 1 μm to 10 mm, more preferably by 20 μm to 1000 μm.

[0066] The second insulating layer 32 covers at least a portion of the exposed surface of the second wiring 4. The exposed surface of the second wiring 4 is the surface of the outer surface of the second wiring 4 that is exposed from the second substrate 3 and the first wiring 2. Specifically, the exposed surface of the second wiring 4 is the surface of the second wiring 4 that is not covered by the second substrate 3 and the first wiring 2. The second insulating layer 32 preferably covers the entire exposed surface of the second wiring 4, but may cover a portion of the exposed surface of the second wiring 4. Furthermore, the second insulating layer 32 does not overlap the first wiring 2 in the first direction X, but a portion of the second insulating layer 32 may overlap the first wiring 2 in the first direction X. According to the above configuration, the second insulating layer 32 prevents short-circuiting between adjacent second wirings 4 due to water droplets or foreign matter, thereby improving reliability.

[0067] It is also possible to provide only one of the first insulating layer 31 and the second insulating layer 32. Furthermore, at least one of the first insulating layer 31 and the second insulating layer 32 may be provided for the stretchable devices 101 and 102 according to the second and third embodiments.

[0068] Fifth Embodiment Next, a fifth embodiment will be described with reference to Fig. 7. Fig. 7 is a partial cross-sectional view of a stretchable device 104 according to the fifth embodiment. The stretchable device 104 according to the fifth embodiment differs from the stretchable device 103 according to the fourth embodiment in that a third insulating layer is provided.

[0069] 7 , the stretchable device 104 of the fifth embodiment further includes a third insulating layer 33. The material of the third insulating layer 33 is preferably the same as the material of the first insulating layer 31 and the second insulating layer 32.

[0070] The third insulating layer 33 is disposed between the first wiring 2 and the first substrate 1 in the first direction X. In other words, the third insulating layer 33 is provided on the first main surface 1 a of the first substrate 1 and is in contact with the lower surface of the first wiring 2.

[0071] If the first substrate 1 is moisture permeable, moisture may penetrate from the first substrate 1 to the first wiring 2, causing ion migration. By providing the third insulating layer 33, it is possible to suppress the penetration of moisture from the first substrate 1 to the first wiring 2. In other words, a stretchable device 104 is provided in which short-circuiting of the first wiring 2 is suppressed.

[0072] It should be noted that a third insulating layer 33 may be provided to the stretchable devices 100, 101, and 102 according to the first, second, and third embodiments.

[0073] Furthermore, the third insulating layer 33 may be disposed, for example, so as to cover only the lower surface of the first wiring 2, or may be disposed in a portion of the first substrate 1 where there is no first wiring 2. The third insulating layer 33 may be disposed so as to cover the entire first substrate 1. As long as the third insulating layer 33 is in contact with the first wiring 2, a different layer may be disposed between the first substrate 1 and the third insulating layer 33.

[0074] Sixth Embodiment Next, a sixth embodiment will be described with reference to Fig. 8. Fig. 8 is a partial cross-sectional view of a stretchable device 105 according to the sixth embodiment. The stretchable device 105 according to the sixth embodiment differs from the stretchable device 103 according to the fourth embodiment in that a first covering layer and a second covering layer are provided.

[0075] 8 , the stretchable device 105 of the sixth embodiment further includes a first covering layer 51 and a second covering layer 52. The materials of the first covering layer 51 and the second covering layer 52 are different from the material of the first protective layer 6.

[0076] The first covering layer 51 covers at least the end of the second substrate 3 on the first substrate side. With the above-described structure, the second substrate 3 can be protected from external forces. More preferably, the first covering layer 51 covers the first main surface 1a side of the first substrate 1. Specifically, the first covering layer 51 covers at least a portion of the second main surface 3b of the second substrate 3, at least a portion of the first insulating layer 31, at least a portion of the first protective layer 6, and at least a portion of the second main surface 3b of the second substrate 3. With the above-described structure, the first wiring 2 and the first protective layer 6 can be protected from external forces.

[0077] An example of the first covering layer 51 is a resin material. For example, the first covering layer 51 is preferably a flexible resin. Specifically, the first covering layer 51 is formed of an ionomer resin, a polyester resin, a styrene resin, an olefin resin, an epoxy resin, a urethane resin, an acrylic resin, or a silicone resin, and is preferably formed of a silicone resin. The first covering layer 51 may be a thermoplastic resin. The first covering layer 51 may be composed of multiple components. Using a resin for the first covering layer 51 can better protect the connection portion from external forces.

[0078] The second covering layer 52 covers at least the end of the second substrate 3 on the first substrate side. With the above-described structure, the second substrate 3 can be protected from external forces. More preferably, the second covering layer 52 covers the first main surface 3a side of the second substrate 3. Specifically, the second covering layer 52 covers at least a portion of the second main surface 1b of the first substrate 1, at least a portion of the second insulating layer 32, and at least a portion of the first main surface 3a of the second substrate 3. With the above-described structure, the second wiring 4 and the first protective layer 6 can be protected from external forces.

[0079] An example of the second coating layer 52 is a resin material. For example, the second coating layer 52 is preferably a flexible resin. Specifically, the second coating layer 52 is formed of an ionomer resin, a polyester resin, a styrene resin, an olefin resin, an epoxy resin, a urethane resin, an acrylic resin, or a silicone resin, and is preferably formed of a silicone resin. The second coating layer 52 may be a thermoplastic resin. The second coating layer 52 may be composed of multiple components. The first coating layer 51 and the second coating layer 52 may be the same component or different components.

[0080] Resin-containing members such as the first protective layer 6, the first insulating layer 31, and the second insulating layer 32 may be cytotoxic. By providing the first covering layer 51, it is possible to suppress leakage of cytotoxic components. The same effect can be achieved with the second covering layer 52. Furthermore, by providing the first covering layer 51 and the second covering layer 52, it is possible to further suppress leakage of cytotoxic components.

[0081] It is also possible to provide only one of the first covering layer 51 and the second covering layer 52. Furthermore, at least one of the first covering layer 51 and the second covering layer 52 may be provided on the stretchable devices 100, 101, 102, and 104 according to the first, second, third, and fifth embodiments.

[0082] Seventh Embodiment Next, a seventh embodiment will be described with reference to Fig. 9. Fig. 9 is a partial cross-sectional view of a stretchable device 106 according to the seventh embodiment. The stretchable device 106 according to the seventh embodiment differs from the stretchable device 100 according to the first embodiment in that a connecting member is provided.

[0083] As shown in Fig. 9 , the stretchable device 106 of the seventh embodiment further includes a connection member 5. For convenience, the connection member 5 is indicated by hatching with dots in Fig. 9 . The connection member 5 electrically connects the first wiring 2 and the second wiring 4.

[0084] A portion of the connection member 5 is located between the first wiring 2 and the second wiring 4. A portion of the connection member 5 is located outside the first end 21 of the first wiring 2 so as to cover the first end 21 of the first wiring 2. A portion of the connection member 5 is located between the first end 41 of the second wiring 4 and the first protective layer 6 so as to cover the first end 41 of the second wiring 4. Examples of the connection member 5 include anisotropic conductive film (ACF), conductive paste, and solder. The connection member 5 preferably contains resin and conductive particles. The conductive particles contained in the connection member 5 come into contact with the first wiring 2 and the second wiring 4, thereby electrically connecting the first wiring 2 and the second wiring 4.

[0085] Furthermore, the connection member 5 connects the first wiring 2 and the second wiring 4. The connection member 5 also contacts the first main surface 1 a of the first substrate 1 and the first main surface 3 a of the second substrate 3, connecting the first substrate 1 and the second substrate 3.

[0086] Next, the connection of the stretchable device 106 will be described. When connecting the first substrate 1 and the second substrate 3, the first substrate 1 and the second substrate 3 may be pressure-bonded, such as by applying pressure. By performing such a process, the connection member 5 deforms and the overall thickness changes. In other words, a low profile of the stretchable device 106 can be achieved. Furthermore, as described above, when the connection member 5 contains conductive particles and is provided between the first wiring 2 and the second wiring 4, electrical continuity cannot be achieved if the distance between the first wiring 2 and the second wiring 4 in the first direction X is greater than the maximum diameter of the conductive particles. In such a case, pressure-bonding as described above reduces the distance between the first wiring 2 and the second wiring 4 in the first direction X. Therefore, electrical connection between the first wiring 2 and the second wiring 4 can be more reliably achieved.

[0087] Note that if the first wiring 2 and the second wiring 4 are electrically connected before the pressure-bonding, the pressure-bonding does not have to be performed. Also, if the connection member 5 has adhesive properties, the pressure-bonding does not have to be performed. Also, the pressure-bonding method is not particularly limited.

[0088] The present disclosure is not limited to the above-described embodiments, and design modifications are possible within the scope of the present disclosure. For example, the features of the first to seventh embodiments may be combined in various ways.

[0089] The present disclosure includes the following aspects: <1> A stretchable device comprising: a first substrate having stretchability; a first wiring provided on a first main surface of the first substrate; a second substrate facing the first substrate in a first direction that is a thickness direction of the first substrate and connected to the first substrate; a second wiring provided on the first main surface of the second substrate and facing the first wiring in the first direction; and a first protective layer provided continuously on the first main surface of the first substrate and on the second main surface of the second substrate so as to cover at least a portion of the first wiring and at least a portion of the second substrate, wherein the first wiring and the second wiring are electrically connected to each other in an overlapping region where they overlap when viewed from the first direction, and the first protective layer overlaps the entire overlapping region when viewed from the first direction. <2> The stretchable device according to <1>, wherein the first protective layer covers the entire first wiring. <3> The stretchable device according to <1> or <2>, wherein the second wiring has a non-overlapping region that does not overlap with the first wiring, when viewed from the first direction, the first protective layer overlaps with the entire non-overlapping region, when viewed from the first direction, and a portion of the first protective layer that overlaps with the non-overlapping region and a portion of the first protective layer that overlaps with the overlapping region are continuous, <4> The stretchable device according to <1> or <2>, wherein the second wiring has a non-overlapping region that does not overlap with the first wiring, when viewed from the first direction, the first protective layer overlaps with a part of the non-overlapping region, when viewed from the first direction, and a portion of the first protective layer that overlaps with the non-overlapping region and a portion of the first protective layer that overlaps with the overlapping region are continuous, when viewed from the first direction. <5> The stretchable device according to <4>, wherein, when viewed from the first direction, a first protective layer end of the first protective layer is located between a first end on the overlapping region side in an extension direction of the first wiring and a second end on the opposite side to the overlapping region in an extension direction of the second wiring. <6> The stretchable device according to any one of <1> to <5>, further comprising a second protective layer provided continuously on the first main surface of the second substrate and on the second main surface of the first substrate so as to cover at least a part of the second wiring and at least a part of the first substrate.<7> The stretchable device according to any one of <1> to <6>, further comprising a first insulating layer covering at least a part of the exposed surface of the first wiring. <8> The stretchable device according to any one of <1> to <7>, further comprising a second insulating layer covering at least a part of the exposed surface of the second wiring. <9> The stretchable device according to any one of <1> to <8>, further comprising a third insulating layer between the first wiring and the first base material. <10> The stretchable device according to any one of <1> to <9>, further comprising a first covering layer covering a first main surface side of the first base material. <11> The stretchable device according to any one of <1> to <10>, further comprising a second covering layer covering a first main surface side of the second base material.

[0090] This application claims priority based on Japanese Patent Application No. 2022-155142, filed on September 28, 2022, the entire contents of which are incorporated herein by reference.

[0091] 100, 101, 102, 103, 104, 105, 106 Stretchable device 1 First substrate 1a First main surface 1b Second main surface 2 First wiring 21 First end 22 Second end 3 Second substrate 3a First main surface 3b Second main surface 4 Second wiring 41 First end 42 Second end 5 Connecting member 6 First protective layer 61 First protective layer end 7 Second protective layer 71 Second protective layer end 31 First insulating layer 32 Second insulating layer 33 Third insulating layer 51 First covering layer 52 Second covering layer L1, L2, L3 Length P1 Portion of first protective layer overlapping with first non-overlapping region P2 Portion of first protective layer overlapping with overlapping region P3 Portion of second protective layer overlapping with second non-overlapping region P4 Portion of second protective layer overlapping with overlapping region X First direction Z1 Overlapping area Z2 First non-overlapping area Z3 Second non-overlapping area

Claims

1. A first base material having elasticity; A first wiring provided on a first main surface of the first base material; a second base material that faces the first base material in a first direction that is a thickness direction of the first base material and is connected to the first base material; a second wiring provided on a first main surface of the second base material and facing the first wiring in the first direction; a first protective layer provided continuously on the first main surface of the first base material and on the second main surface of the second base material so as to cover at least a portion of the first wiring and at least a portion of the second base material; Equipped with the first wiring and the second wiring are electrically connected to each other in an overlapping region where the first wiring and the second wiring overlap each other when viewed from the first direction; the first protective layer overlaps with the entire overlap region when viewed from the first direction, The first base material and the second base material have a base material non-overlapping region in which they do not overlap when viewed from the first direction, The first protective layer does not overlap at least a portion of the base material non-overlapping region when viewed from the first direction. Stretchable devices.

2. The stretchable device according to claim 1 , wherein the first protective layer covers the entire first wiring.

3. the second wiring has a non-overlapping region that does not overlap with the first wiring when viewed from the first direction, the first protective layer overlaps with the entire non-overlapping region when viewed from the first direction; The stretchable device according to claim 1 or 2, wherein a portion of the first protective layer overlapping the non-overlapping region and a portion of the first protective layer overlapping the overlapping region are continuous when viewed from the first direction.

4. the second wiring has a non-overlapping region that does not overlap with the first wiring when viewed from the first direction, the first protective layer overlaps a portion of the non-overlapping region when viewed from the first direction; The stretchable device according to claim 1 or 2, wherein a portion of the first protective layer overlapping the non-overlapping region and a portion of the first protective layer overlapping the overlapping region are continuous when viewed from the first direction.

5. When viewed from the first direction, a first protective layer end of the first protective layer is located between a first end on the overlapping region side in the extension direction of the first wiring and a second end on the opposite side to the overlapping region in the extension direction of the second wiring. The stretchable device according to claim 4.

6. 3. The stretchable device according to claim 1 or 2, further comprising a second protective layer provided continuously on the first main surface of the second substrate and on the second main surface of the first substrate so as to cover at least a portion of the second wiring and at least a portion of the first substrate.

7. The stretchable device according to claim 1 or 2, further comprising a first insulating layer covering at least a portion of the exposed surface of the first wiring.

8. The stretchable device according to claim 1 or 2, further comprising a second insulating layer covering at least a portion of the exposed surface of the second wiring.

9. The stretchable device according to claim 1 or 2, further comprising a third insulating layer between the first wiring and the first substrate.

10. The stretchable device according to claim 1 or 2, further comprising a first covering layer covering a first main surface side of the first substrate.

11. The stretchable device according to claim 1 or 2, further comprising a second covering layer covering the first main surface side of the second substrate.