Stretchable wiring board

Abstract

A stretchable wiring board 1A is provided with: a stretchable substrate 10A having a first principal surface 10Aa and a second principal surface 10Ab facing one another in a thickness direction T; a wiring member 20A that is provided to at least the first principal surface 10Aa side of the stretchable substrate 10A, and comprises at least one stretchable wiring that extends in planar directions that include a length direction L orthogonal to the thickness direction T as well as a width direction W orthogonal to the thickness direction T and to the length direction L; a protective member 40A for covering the first principal surface 10Aa and / or the second principal surface 10Ab of the stretchable substrate 10A; and a film member 50A provided to the protective member 40A on a stretchable substrate 10A side and / or an opposite side from the stretchable substrate 10A. When stretched in the length direction L, the film member 50A experiences an irreversible change in appearance.

Description

[Technical field]

[0001] The present invention relates to a stretchable wiring board. [Background technology]

[0002] Patent Document 1 discloses a cord-like thermal fuse having a linear fuse disposed within an insulating sheathed tube, characterized in that the linear fuse is bent into a shape that is elastic in the longitudinal direction. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 10-188756 Summary of the Invention [Problem to be solved by the invention]

[0004] In recent years, the condition of the human body has been managed by acquiring and analyzing biological information (vital signs) using a stretchable wiring board. When a stretchable wiring board is used in a state where it is attached to the human body, for example, the wiring used in the stretchable wiring board is required to have stretchability that allows it to follow the movement of the human body. In other words, the wiring used in the stretchable wiring board is required to be a stretchable wiring having stretchability.

[0005] However, even if the wiring used in the elastic wiring board is elastic wiring, if the elastic wiring board is stretched more than expected, the resistance of the elastic wiring board is likely to increase with the stretching of the elastic wiring board. If the resistance of the elastic wiring increases in this way, the elastic wiring may heat up and become easily disconnected when an excessive current flows through the elastic wiring. Furthermore, if the elastic wiring board is used while the resistance of the elastic wiring is still high, there is a risk that errors will occur in the acquired biometric information, or that the elastic wiring may heat up when an excessive current flows through it, causing adverse effects such as burns to the human body.

[0006] In response to this, it is conceivable to incorporate an expandable fuse such as the cord-shaped thermal fuse described in Patent Document 1 into the expandable wiring board, so that when an overcurrent flows through the expandable wiring in a state where the expandable wiring board is stretched more than expected, the fuse will blow, electrically destroying the expandable wiring board. However, it is technically difficult to incorporate the cord-shaped thermal fuse having a hollow structure described in FIG. 1 of Patent Document 1 into the expandable wiring board. Even if it were possible to incorporate the cord-shaped thermal fuse described in Patent Document 1 into the expandable wiring board, the expandable wiring board would reach a high temperature when the cord-shaped thermal fuse blows, which could have an adverse effect on the human body.

[0007] For these reasons, when a stretchable wiring board is used in a state where it is attached to the human body, a mechanism is required that can safely detect an excessively stretched state of the stretchable wiring board.

[0008] The present invention has been made to solve the above problems, and has an object to provide a stretchable wiring board that can safely detect an excessively stretched state. [Means for solving the problem]

[0009] The stretchable wiring board of the present invention comprises a stretchable substrate having a first main surface and a second main surface opposed to each other in a thickness direction, a wiring member provided on at least the first main surface side of the stretchable substrate and consisting of at least one stretchable wiring extending in a plane direction including a length direction perpendicular to the thickness direction and a width direction perpendicular to the thickness direction and the length direction, a protective member covering at least one of the first main surface and the second main surface of the stretchable substrate, and a film member provided on at least one of the stretchable substrate side and the side opposite to the stretchable substrate with respect to the protective member, wherein the appearance of the film member changes irreversibly when stretched in the length direction. Effect of the Invention

[0010] According to the present invention, it is possible to provide a stretchable wiring board capable of safely detecting an excessively stretched state. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a schematic perspective view showing an example of the stretchable wiring board according to the first embodiment of the present invention. [Diagram 2] FIG. 2 is a schematic plan view showing the film member in FIG. 1 in a state before being stretched in the length direction. [Diagram 3] FIG. 3 is a schematic plan view showing the film member in FIG. 1 in a state after being stretched in the length direction. [Figure 4] FIG. 4 is a schematic perspective view showing an example of the stretchable wiring board according to the second embodiment of the present invention. [Diagram 5] FIG. 5 is a schematic plan view showing the film member in FIG. 4 in a state before being stretched in the length direction. [Figure 6] FIG. 6 is a schematic plan view showing the film member in FIG. 4 in a state after it has been stretched in the length direction. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] The stretchable wiring board of the present invention will be described below. Note that the present invention is not limited to the following configurations, and may be appropriately modified within the scope of the present invention. In addition, a combination of multiple individual preferred configurations described below also constitutes the present invention.

[0013] The following embodiments are merely examples, and it goes without saying that partial replacement or combination of the configurations shown in different embodiments is possible. In the second and subsequent embodiments, the description of the matters common to the first embodiment will be omitted, and the differences will be mainly described. In particular, the same effects and advantages due to the same configuration will not be mentioned one by one for each embodiment.

[0014] The drawings shown below are schematic diagrams, and the dimensions, aspect ratio, and scale may differ from those of the actual product.

[0015] The stretchable wiring board of the present invention comprises a stretchable substrate having a first main surface and a second main surface opposed to each other in a thickness direction, a wiring member provided on at least the first main surface side of the stretchable substrate and consisting of at least one stretchable wiring extending in a plane direction including a length direction perpendicular to the thickness direction and a width direction perpendicular to the thickness direction and the length direction, a protective member covering at least one of the first main surface and the second main surface of the stretchable substrate, and a film member provided on at least one of the stretchable substrate side and the side opposite to the stretchable substrate with respect to the protective member, wherein the appearance of the film member changes irreversibly when stretched in the length direction.

[0016] [Embodiment 1] In the stretchable wiring board of the first embodiment of the present invention, the film member changes from a transparent state to an opaque state when stretched in the length direction.

[0017] FIG. 1 is a schematic perspective view showing an example of the stretchable wiring board according to the first embodiment of the present invention.

[0018] The stretchable wiring board 1A shown in FIG. 1 has a stretchable base material 10A, a wiring member 20A, a protective member 40A, and a film member 50A.

[0019] In this specification, the length direction, thickness direction, and width direction are respectively defined as directions L, T, and W as shown in Fig. 1 etc. The length direction L, thickness direction T, and width direction W are mutually orthogonal. Moreover, a direction orthogonal to the thickness direction T and including the length direction L and width direction W is defined as a surface direction.

[0020] In this specification, various dimensions in the length direction, thickness direction, and width direction are shown for the stretchable wiring board in an unstretched state unless otherwise specified. Various dimensions in the length direction, thickness direction, and width direction are measured by viewing the stretchable wiring board in a plan view or cross section with an optical microscope.

[0021] The elastic substrate 10A has a first main surface 10Aa and a second main surface 10Ab that face each other in the thickness direction T.

[0022] The stretchable substrate 10A has a narrow portion 11A whose cross-sectional area when viewed in a cross section perpendicular to the length direction L is the smallest.

[0023] In the example shown in Fig. 1, the dimension of the stretchable substrate 10A in the thickness direction T is constant regardless of the position along the length direction L. That is, in the example shown in Fig. 1, the narrow portion 11A corresponds to the portion of the stretchable substrate 10A whose dimension in the width direction W is the smallest. Note that when the dimension of the stretchable substrate 10A in the width direction W is constant regardless of the position along the length direction L, the narrow portion 11A corresponds to, for example, the portion of the stretchable substrate 10A whose dimension in the thickness direction T is the smallest.

[0024] The stretchable substrate 10A preferably contains at least one resin selected from the group consisting of styrene-based resins, olefin-based resins, and silicone-based resins. Examples of styrene-based resins include styrene-butadiene-styrene copolymer resins (SBS).

[0025] The dimension of the stretchable substrate 10A in the thickness direction T is preferably 100 μm or less, and more preferably 50 μm or less. When the dimension of the stretchable substrate 10A in the thickness direction T is within the above range, the stretchable wiring board 1A can easily follow the movement of the human body when used in a state where the stretchable wiring board 1A is attached to the human body.

[0026] The dimension of the stretchable substrate 10A in the thickness direction T is preferably 10 μm or more.

[0027] The breaking elongation rate of the stretchable substrate 10A in the length direction L is preferably 50% or more. When the breaking elongation rate of the stretchable substrate 10A in the length direction L is within the above range, the stretchable wiring board 1A can easily follow the movement of the human body when used in a state where the stretchable wiring board 1A is attached to the human body.

[0028] From the viewpoint of making it easier for the stretchable wiring board 1A to follow the movements of the human body, the higher the breaking elongation rate in the length direction L of the stretchable base material 10A is, within a range of 50% or more, the more preferable it is.

[0029] The Young's modulus of the stretchable substrate 10A is preferably 100 MPa or less, and more preferably 30 MPa or less. When the Young's modulus of the stretchable substrate 10A is within the above range, when the stretchable wiring board 1A is used in a state where it is attached to the human body, the stretchable wiring board 1A is less likely to hinder the stretching of the surface of the human body, and therefore the stretchable wiring board 1A is less likely to cause discomfort.

[0030] The Young's modulus of the stretchable substrate 10A is preferably 3 MPa or more.

[0031] In the example shown in FIG. 1, the shape of the stretchable substrate 10A when viewed in the thickness direction T is such that the dimension in the width direction W is larger at one end than at the other portion.

[0032] The shape of the stretchable substrate 10A when viewed in the thickness direction T may be a shape in which the dimension in the width direction W is constant regardless of the position along the length direction L.

[0033] Furthermore, the shape of the stretchable substrate 10A when viewed from the thickness direction T may be a shape in which one end is looped, for example, a shape in which a straight portion and a loop portion are connected in the length direction L. In this case, the stretchable substrate 10A may have a narrow portion at the position where the straight portion and the loop portion are connected.

[0034] The wiring member 20A is provided on at least the first main surface 10Aa side of the stretchable substrate 10A.

[0035] In the example shown in FIG. 1, the wiring member 20A is provided on the first main surface 10Aa side of the stretchable substrate 10A.

[0036] The wiring member 20A may be provided on the second main surface 10Ab side of the stretchable substrate 10A, in addition to the first main surface 10Aa side of the stretchable substrate 10A.

[0037] In the example shown in Fig. 1, the wiring member 20A is provided on a first main surface 10Aa of the stretchable base material 10A. That is, in the example shown in Fig. 1, the stretchable base material 10A and the wiring member 20A are in contact with each other.

[0038] It should be noted that another member may be interposed between the stretchable base material 10A and the wiring member 20A.

[0039] The wiring member 20A is composed of at least one elastic wire extending in a planar direction including the length direction L and the width direction W.

[0040] In the example shown in FIG. 1, the wiring member 20A is composed of two elastic wires, an elastic wire 21Aa and an elastic wire 21Ab, which extend in the planar direction.

[0041] The wiring member 20A may be made up of only one elastic wire, or may be made up of three or more elastic wires.

[0042] The dimension of the elastic wiring in the thickness direction T, and the dimension of the elastic wiring 21Aa and the elastic wiring 21Ab in the thickness direction T in the example shown in Fig. 1, is preferably 100 µm or less, more preferably 50 µm or less. By having the dimension of the elastic wiring in the thickness direction T within the above range, when the elastic wiring board 1A is used in a state where it is attached to the human body, the elastic wiring board 1A can easily follow the movement of the human body.

[0043] The dimension of the elastic wire in the thickness direction T, that of the elastic wire 21Aa and the elastic wire 21Ab in the example shown in FIG. 1, is preferably 1 μm or more, and more preferably 10 μm or more.

[0044] The elastic wires, the elastic wires 21Aa and 21Ab in the example shown in FIG. 1, contain, for example, conductive particles and a resin.

[0045] Examples of materials constituting the conductive particles contained in the elastic wiring include metals such as silver, copper, nickel, etc. Among these, silver is preferred from the viewpoint of realizing low resistance of the elastic wiring.

[0046] The average particle size of the conductive particles contained in the elastic wiring is preferably 0.01 μm or more and 10 μm or less.

[0047] The average particle size of the conductive particles contained in the elastic wiring is determined as follows. First, the elastic wiring substrate is polished or the like so that a cross section in which the target elastic wiring is exposed appears. Next, an image of the cross section is taken with a scanning electron microscope (SEM) or the like. Then, the equivalent circle diameter of the conductive particles contained in the elastic wiring is measured by performing image analysis of the taken cross section image, and the obtained equivalent circle diameter is taken as the particle size of the conductive particles. Thereafter, a cumulative particle size distribution based on the number is calculated from the particle size of the conductive particles obtained, and the particle size (median diameter D) at which the cumulative probability in the cumulative particle size distribution based on the number is 50% is determined. 50 ) is defined as the average particle size of the conductive particles.

[0048] The conductive particles contained in the elastic wire are preferably spherical in shape. The conductive particles contained in the elastic wire may be flat, irregularly shaped with protrusions, or the like, in addition to the spherical shape, from the viewpoint of reducing the resistance change of the elastic wire due to stretching.

[0049] When the wiring member 20A is composed of multiple elastic wires, it is preferable that the conductive particles contained in each elastic wire are the same as each other at least in terms of the type of constituent material, but they may be different from each other or may differ in part.

[0050] The resin contained in the elastic wiring is preferably at least one elastomer resin selected from the group consisting of epoxy resins, urethane resins, acrylic resins, and silicone resins. In this case, the elasticity of the elastic wiring is easily ensured. The resin contained in the elastic wiring may be a resin other than the above as long as it can impart the elasticity function.

[0051] When the wiring member 20A is composed of multiple elastic wires, it is preferable that the resin contained in each elastic wire is the same as each other at least in terms of type, but the resins may be different from each other or may be partially different.

[0052] The stretchable wires, the stretchable wires 21Aa and 21Ab in the example shown in FIG. 1, are formed, for example, as follows. First, a conductive paste containing conductive particles and a resin is applied to at least the first main surface 10Aa of the stretchable substrate 10A. Examples of the method for applying the conductive paste include a screen printing method, an inkjet method, and a dispense method. Then, the applied conductive paste is heat-treated to form the stretchable wires.

[0053] 1, each of the elastic wires 21Aa and 21Ab is electrically connected to the electronic component 30. That is, the elastic wires 21Aa and 21Ab constitute an electrical path to the outside, and in the example shown in FIG. 1, an electrical path to the external electronic component 30.

[0054] The electronic component 30 is mounted on each of the elastic wire 21Aa and the elastic wire 21Ab via a bonding member such as solder.

[0055] Examples of the electronic components 30 include diodes, integrated circuits (ICs), capacitors, resistors, inductors, amplifiers (op-amps, transistors, etc.), and the like.

[0056] The protective member 40A covers at least one of the first main surface 10Aa and the second main surface 10Ab of the stretchable substrate 10A.

[0057] In the example shown in FIG. 1, the protective member 40A covers both the first main surface 10Aa and the second main surface 10Ab of the stretchable substrate 10A.

[0058] The protective member 40A may cover only the first main surface 10Aa of the stretchable substrate 10A, or may cover only the second main surface 10Ab of the stretchable substrate 10A.

[0059] In the example shown in Fig. 1, the protective member 40A is composed of a first protective part 40Aa and a second protective part 40Ab. In the example shown in Fig. 1, the first protective part 40Aa covers the first main surface 10Aa of the stretchable substrate 10A, and the second protective part 40Ab covers the second main surface 10Ab of the stretchable substrate 10A.

[0060] 1, the protective member 40A, more specifically, the first protective portion 40Aa, covers the first main surface 10Aa of the stretchable base material 10A, and also covers the wiring member 20A and the electronic component 30. Covering the wiring member 20A and the electronic component 30 with the protective member 40A provides the following effects. The wiring member 20A and the electronic component 30 are protected from the outside. The moisture resistance of the wiring member 20A and the electronic component 30 is improved. Chemical substances used in the wiring member 20A and the electronic components 30 are prevented from coming into contact with the human body. Electric leakage from the wiring member 20A and the electronic component 30 to the human body is prevented.

[0061] Examples of materials for the protective member 40A, and for the first protective portion 40Aa and the second protective portion 40Ab in the example shown in FIG. 1, include elastomer resins such as polyvinyl chloride, polyethylene, polystyrene, polycarbonate, polyvinylidene fluoride, polyimide, liquid crystal polymer, polytetrafluoroethylene, phenolic resin, epoxy resin, urethane resin, acrylic resin, silicone resin, and styrene-butadiene resin.

[0062] The protective member 40A is formed, for example, by pressing a film containing the above-mentioned material onto at least one of the first main surface 10Aa and the second main surface 10Ab of the stretchable substrate 10A. Alternatively, the protective member 40A is formed, for example, by applying a slurry containing the above-mentioned material onto at least one of the first main surface 10Aa and the second main surface 10Ab of the stretchable substrate 10A, and then subjecting the applied slurry to a heat treatment or UV treatment. Examples of the method for applying the slurry include a screen printing method, an inkjet method, and a dispense method.

[0063] The film member 50A is provided on at least one of the side of the stretchable substrate 10A and the side opposite to the stretchable substrate 10A with respect to the protective member 40A.

[0064] In the example shown in FIG. 1, the film member 50A is provided on the opposite side of the protective member 40A to the stretchable substrate 10A.

[0065] In the example shown in Fig. 1, the film member 50A is provided on the side of the first protective part 40Aa opposite the stretchable substrate 10A. In the example shown in Fig. 1, by providing the film member 50A on the side of the first protective part 40Aa opposite the stretchable substrate 10A, the area where the film member 50A is provided, that is, the area where the first protective part 40Aa and the film member 50A overlap, is mechanically reinforced.

[0066] The film member 50A may be provided on the opposite side of the second protective portion 40Ab to the stretchable substrate 10A.

[0067] Furthermore, the film member 50A may be provided on both the side of the first protective portion 40Aa opposite the stretchable substrate 10A and the side of the second protective portion 40Ab opposite the stretchable substrate 10A.

[0068] 1, the film member 50A is provided on the main surface of the first protective part 40Aa opposite to the stretchable substrate 10A. That is, in the example shown in FIG 1, the protective member 40A and the film member 50A are in contact with each other.

[0069] It should be noted that another member may be interposed between the protection member 40A and the film member 50A.

[0070] The film member 50A may be provided on the stretchable substrate 10A side of the protective member 40A. More specifically, the film member 50A may be provided only on the stretchable substrate 10A side of the first protective portion 40Aa, only on the stretchable substrate 10A side of the second protective portion 40Ab, or on both the stretchable substrate 10A side of the first protective portion 40Aa and the stretchable substrate 10A side of the second protective portion 40Ab.

[0071] The film member 50A may be provided on both the side of the protective member 40A facing the stretchable substrate 10A and the side of the protective member 40A opposite to the stretchable substrate 10A.

[0072] As described above, in the example shown in FIG. 1, each of the elastic wire 21Aa and the elastic wire 21Ab is electrically connected to the electronic component 30.

[0073] For example, when a light-emitting diode, which is a type of diode, is used as the electronic component 30, the stretchable wiring 21Aa and the stretchable wiring 21Ab function as drive wiring through which a large current flows for driving the light-emitting diode. In this case, if the stretchable wiring board 1A is excessively stretched in the length direction L, the resistance of the stretchable wiring 21Aa and the stretchable wiring 21Ab becomes too high as the stretchable wiring 21Aa and the stretchable wiring 21Ab stretch, and this may make it difficult for a large current for driving the light-emitting diode to flow to the light-emitting diode via the stretchable wiring 21Aa and the stretchable wiring 21Ab, or the stretchable wiring 21Aa and the stretchable wiring 21Ab may become more likely to break when a large current flows, or the stretchable wiring 21Aa and the stretchable wiring 21Ab may become more likely to generate heat when a large current flows. In this way, if the stretchable wiring board 1A is excessively stretched in the length direction L, the light-emitting diode serving as the electronic component 30 may not light up, or the stretchable wiring 21Aa and the stretchable wiring 21Ab may generate excessive heat.

[0074] In contrast, in the stretchable wiring board 1A, the appearance of the film member 50A changes irreversibly when it is stretched in the length direction L. In the stretchable wiring board 1A, by utilizing the fact that the appearance of the film member 50A changes irreversibly when it is stretched in the length direction L, it is possible to detect an excessively stretched state of the stretchable wiring board 1A, such as the stretchable wiring board 1A being excessively stretched in the length direction L, before a defect occurs, such as the stretchable wiring 21Aa and the stretchable wiring 21Ab being broken due to the stretchable wiring 21Aa and the stretchable wiring 21Ab being excessively stretched in the length direction L.

[0075] In the stretchable wiring board 1A, by determining in advance the elongation rate of the film member 50A and the timing at which the appearance of the film member 50A changes, and then providing the film member 50A as described above, it is possible to adjust the timing at which the appearance of the film member 50A changes when the stretchable wiring board 1A is stretched in the longitudinal direction L, i.e., the timing at which an excessively elongated state of the stretchable wiring board 1A is detected.

[0076] In the stretchable wiring board 1A, the appearance of the film member 50A changes irreversibly when it is stretched in the length direction L, and this makes it possible to leave a trace that the stretchable wiring board 1A has been excessively stretched in the length direction L. In other words, from the stretchable wiring board 1A in which the appearance of the film member 50A has changed, it is possible to confirm a past history of the stretchable wiring board 1A having been excessively stretched in the length direction L.

[0077] Furthermore, when the stretchable wiring board 1A is used, the user can be prompted to stop using the stretchable wiring board 1A at the time when the appearance of the film member 50A changes, that is, before the stretchable wiring 21Aa and the stretchable wiring 21Ab are excessively stretched in the length direction L. In other words, when the stretchable wiring board 1A is used, the user can be prompted to stop using the stretchable wiring board 1A before the stretchable wiring 21Aa and the stretchable wiring 21Ab generate excessive heat due to the stretchable wiring 21Aa and the stretchable wiring 21Ab being excessively stretched in the length direction L. Therefore, when the stretchable wiring board 1A is used, not only the stretchable wiring 21Aa and the stretchable wiring 21Ab do not generate excessive heat, but the excessive heat generated by the stretchable wiring 21Aa and the stretchable wiring 21Ab is prevented from being exposed to the user's body, and as a result, safety is improved.

[0078] As described above, according to the stretchable wiring board 1A, it is possible to realize a stretchable wiring board capable of safely detecting an excessively stretched state.

[0079] In this specification, the appearance of the film member changes irreversibly when it is stretched in the longitudinal direction means that the appearance of the film member changes when it is stretched in the longitudinal direction, and the appearance does not return to the original state even if the film member is contracted to the state before being stretched after being stretched in the longitudinal direction. The appearance of the film member includes the color, shape, etc. of the film member.

[0080] Fig. 2 is a schematic plan view showing the film member in Fig. 1 before it is stretched in the length direction, and Fig. 3 is a schematic plan view showing the film member in Fig. 1 after it has been stretched in the length direction.

[0081] The film member 50A shown in Fig. 2, which is in a state before being stretched in the length direction L, is in a transparent state. In contrast, the film member 50A shown in Fig. 3, which is in a state after being stretched in the length direction L, is in an opaque state. In this way, the film member 50A changes from a transparent state to an opaque state when stretched in the length direction L. On the other hand, even if the film member 50A is shrunk to the state before being stretched in the length direction L after being stretched in the length direction L and changing from a transparent state to an opaque state, it does not change from the opaque state to a transparent state.

[0082] In this specification, the change of a film member from a transparent state to an opaque state means that when white light having a wavelength of 450 nm or more and 780 nm or less is transmitted through the film member, the transmittance defined by the following formula (1) changes from a state of 95% or more to a state of 90% or less. Transmittance (%) = 100 x transmitted light intensity / light source intensity...(1)

[0083] An example of a mode in which the film member 50A changes from a transparent state to an opaque state when it is stretched in the length direction L will be described below.

[0084] The film member 50A may be made of a resin that changes from an amorphous state to a crystalline state when the film member 50A is stretched in the length direction L. In this case, the molecular structure of the resin constituting the film member 50A is in an amorphous state (also called amorphous plastic) before the film member 50A is stretched in the length direction L, so that the film member 50A is in a transparent state that transmits light before being stretched in the length direction L. In contrast, the molecular structure of the resin constituting the film member 50A changes to a crystalline state (also called crystalline plastic) when the film member 50A is stretched in the length direction L, so that the film member 50A is in an opaque state that diffuses light after being stretched in the length direction L.

[0085] In this specification, the change of a resin from an amorphous state to a crystalline state means that in the solidified state of the resin, the string-like polymers change from a state in which they are irregularly entangled to a state in which they are regularly arranged, and preferably the degree of orientation of the resin changes from a state in which it is 1% or less to a state in which it is 20% or more. The degree of orientation of the resin is calculated, for example, from the crystalline peak of the resin measured by X-ray diffraction or the like.

[0086] When the film member 50A is made of a resin that changes from an amorphous state to a crystalline state when the film member 50A is stretched in the length direction L, the material of the film member 50A is preferably polyethylene.

[0087] The film member 50A may contain microcapsules encapsulating a pigment that can be broken when the film member 50A is stretched in the length direction L. In this case, when the film member 50A is stretched in the length direction L, the microcapsules contained in the film member 50A are broken and the pigment seeps out, causing the color of the film member 50A to change overall and become opaque.

[0088] As described above, when the film member 50A is stretched in the length direction L, it changes from a transparent state to an opaque state, and thereby the color, as an example of the appearance, changes irreversibly.

[0089] As described above, the narrow portion 11A corresponds to the portion of the stretchable substrate 10A that has the smallest cross-sectional area when viewed in a cross section perpendicular to the longitudinal direction L. Therefore, when the stretchable wiring board 1A is stretched in the longitudinal direction L, stress tends to concentrate in the narrow portion 11A in the stretchable substrate 10A, and as a result, the narrow portion 11A stretches more easily than other portions.

[0090] In contrast, in the stretchable wiring board 1A, the film member 50A is provided at a position overlapping the narrow portion 11A when viewed from the thickness direction T. That is, in the stretchable wiring board 1A, the film member 50A, whose appearance changes irreversibly when stretched in the length direction L, is provided in the narrow portion 11A, which stretches the most when the stretchable base material 10A is stretched in the length direction L. Therefore, according to the stretchable wiring board 1A in which the film member 50A is provided in the narrow portion 11A, the appearance of the film member 50A is more likely to change earlier when stretched in the length direction L, compared to a stretchable wiring board in which the film member 50A is not provided in the narrow portion 11A, and therefore an excessively stretched state can be detected earlier.

[0091] In the example shown in FIG. 1, the film member 50A is provided only at a position overlapping the narrow portion 11A when viewed in the thickness direction T.

[0092] The film member 50A may be provided at a position that does not overlap the narrow portion 11A when viewed from the thickness direction T, in addition to being provided at a position that overlaps the narrow portion 11A when viewed from the thickness direction T.

[0093] The tensile strength of the film member 50A in the length direction L is preferably lower than the tensile strength of the wiring member 20A in the length direction L. In this case, when the stretchable wiring board 1A is stretched in the length direction L, the film member 50A will break before the wiring member 20A breaks due to excessive stretching of the wiring member 20A in the length direction L. As a result, when the film member 50A is stretched in the length direction L, not only the color, but also the shape, as an example of the appearance, will change irreversibly, making it easier to detect an excessively stretched state of the stretchable wiring board 1A.

[0094] The tensile strength in the length direction L of the protective member 40A, and the tensile strength in the length direction L of each of the first protective portion 40Aa and the second protective portion 40Ab in the example shown in Fig. 1, is preferably higher than the tensile strength in the length direction L of the wiring member 20A. In this case, when the stretchable wiring board 1A is stretched in the length direction L, the protective member 40A does not break before the wiring member 20A. In other words, when the stretchable wiring board 1A is stretched in the length direction L, at the time when the wiring member 20A breaks due to the wiring member 20A being excessively stretched in the length direction L, the protective member 40A does not break. Therefore, when the stretchable wiring board 1A is used, the user can be prompted to stop using the stretchable wiring board 1A at the point in time when the film member 50A detects that the wiring member 20A has been excessively stretched in the length direction L, that is, before a problem occurs such as chemical substances used in the wiring member 20A and the electronic component 30 coming into contact with the human body or electric leakage from the wiring member 20A and the electronic component 30 to the human body due to the protective member 40A breaking. As a result, safety is improved when using the stretchable wiring board 1A having the protective member 40A.

[0095] The breaking elongation rate in the length direction L of the protective member 40A, and the breaking elongation rate in the length direction L of each of the first protective portion 40Aa and the second protective portion 40Ab in the example shown in FIG. 1, is preferably 200% or more.

[0096] The breaking elongation rate in the length direction L of the protective member 40A, and the breaking elongation rate in the length direction L of each of the first protective portion 40Aa and the second protective portion 40Ab in the example shown in FIG. 1, is preferably 800% or less.

[0097] The stretchable wiring board 1A may further have an electrode connected to at least one of the stretchable wiring 21Aa and the stretchable wiring 21Ab. The stretchable wiring board 1A can function as a sensor by being attached to the human body via such an electrode. In this case, the stretchable wiring board 1A can detect that at least one of the stretchable wiring 21Aa and the stretchable wiring 21Ab connected to the electrode is in an excessively stretched state before being broken due to excessive stretching in the length direction L, that is, before an abnormality occurs in the sensor. This makes it possible to prompt the user to stop using the stretchable wiring board 1A before an abnormality occurs in the sensor, thereby preventing problems such as obtaining erroneous bioinformation or being diagnosed based on erroneous bioinformation.

[0098] The electrode is preferably a gel electrode. The use of a gel electrode makes it easier to attach the elastic wiring board 1A to the human body. The gel electrode is made of a conductive gel material that contains, for example, water, alcohol, a moisturizer, an electrolyte, and the like. Examples of such gel materials include hydrogels.

[0099] [Embodiment 2] In the stretchable wiring board of the second embodiment of the present invention, the film member is provided with a notch that can be broken when stretched in the length direction. The stretchable wiring board of the second embodiment of the present invention is otherwise similar to the stretchable wiring board of the first embodiment of the present invention.

[0100] FIG. 4 is a schematic perspective view showing an example of the stretchable wiring board according to the second embodiment of the present invention.

[0101] The stretchable wiring board 1B shown in Fig. 4 has a stretchable base material 10A, a wiring member 20A, a protective member 40A, and a film member 50B. In other words, the stretchable wiring board 1B differs from the stretchable wiring board 1A in that it has a film member 50B instead of the film member 50A.

[0102] Fig. 5 is a plan view schematic diagram showing the state of the film member in Fig. 4 before it is stretched in the length direction. Fig. 6 is a plan view schematic diagram showing the state of the film member in Fig. 4 after it has been stretched in the length direction.

[0103] The film member 50B has a slit 51 that can be broken when stretched in the length direction L. In the film member 50B shown in FIG. 5 , which shows the state before being stretched in the length direction L, the slit 51 is not broken. In contrast, in the film member 50B shown in FIG. 6 , which shows the state after being stretched in the length direction L, the slit 51 is broken at the breaking point 52. In this manner, the shape of the film member 50B changes when it is stretched in the length direction L. On the other hand, even if the film member 50B is shrunk to the state before being stretched in the length direction L after its shape is changed by being stretched in the length direction L, the slit 51 remains broken at the breaking point 52, and the shape does not return to its original state.

[0104] As described above, when the film member 50B is stretched in the length direction L, the shape, which is an example of its appearance, changes irreversibly.

[0105] Therefore, according to the stretchable wiring board 1B, by utilizing the fact that the appearance of the film member 50B changes irreversibly when stretched in the length direction L, it is possible to realize a stretchable wiring board that can safely detect an excessively stretched state, similar to the stretchable wiring board 1A.

[0106] In the following, an example of a state in which the shape of the film member 50B is likely to change when it is stretched in the length direction L will be described.

[0107] In the film member 50B, the cuts 51 are preferably provided along the width direction W.

[0108] In the stretchable wiring board 1B, by determining in advance the relationship between the dimension D2 of the notch 51 in the width direction W and the breaking elongation rate in the length direction L of the film member 50B until the notch 51 breaks, and then providing the notch 51 along the width direction W as described above, it is possible to adjust the timing at which the appearance of the film member 50B changes (the notch 51 breaks) when the stretchable wiring board 1B is stretched in the length direction L, i.e., the timing at which the excessive stretched state of the stretchable wiring board 1B is detected.

[0109] In the stretchable wiring board 1B, the breaking elongation rate in the length direction L of the film member 50B until the incisions 51 break can be adjusted not only by the dimension D2 of the incisions 51 in the width direction W, but also by the distance D1 between the incisions 51 in the length direction L and the distance D3 between the incisions 51 in the width direction W. For example, by shortening the distance D1 between the incisions 51 in the length direction L and lengthening the dimension D2 of the incisions 51 in the width direction W, the breaking elongation rate in the length direction L of the film member 50B until the incisions 51 break can be increased.

[0110] In the film member 50B, the cuts 51 may be provided along a surface direction other than the width direction W (for example, the length direction L).

[0111] It is preferable that the film member 50B has a plurality of cuts 51. In this case, the plurality of cuts 51 are preferably arranged in the same straight line along the width direction W. It is also preferable that the plurality of cuts 51 are arranged in the same straight line along the width direction W such that the rows of cuts 51 are spaced apart in the length direction L.

[0112] In the stretchable wiring board 1B, by determining in advance the relationship between the number, arrangement, etc. of the notches 51 and the breaking elongation rate in the length direction L of the film member 50B until the notches 51 break, and then setting the number, arrangement, etc. of the notches 51 as described above, it is possible to adjust the timing at which the appearance of the film member 50B changes (the notches 51 break) when the stretchable wiring board 1B is stretched in the length direction L, i.e., the timing at which the excessive stretched state of the stretchable wiring board 1B is detected.

[0113] In addition, only one cut 51 may be provided in the film member 50B.

[0114] The film member 50B is preferably made of a non-elastic resin. In this case, when the film member 50B is stretched in the length direction L, the incisions 51 are more likely to break sooner, and therefore the appearance of the film member 50B is more likely to change sooner.

[0115] In this specification, a resin being inelastic means that when the resin in question is molded into a resin film having a length of 18 mm, a width of 5 mm and a thickness of 38 μm, the tensile modulus of elasticity in the longitudinal direction of the resin film is 1 GPa or more.

[0116] When the film member 50B is made of a non-elastic resin, the material of the film member 50B is preferably at least one of polyethylene terephthalate and polyimide. That is, the material of the film member 50B is preferably polyethylene terephthalate, or preferably polyimide, or more preferably a mixture of polyethylene terephthalate and polyimide.

[0117] In each of the above embodiments, the stretchable wiring board is stretched in the length direction when the stretchable wiring board is used. However, the stretchable wiring board may be stretched in a surface direction other than the length direction (e.g., the width direction) in addition to the length direction.

[0118] The present specification discloses the following:

[0119] <1> An elastic substrate having a first main surface and a second main surface opposed to each other in a thickness direction; A wiring member consisting of at least one elastic wiring provided on at least the first main surface side of the elastic base material and extending in a surface direction including a length direction perpendicular to the thickness direction and a width direction perpendicular to the thickness direction and the length direction; A protective member covering at least one of the first main surface and the second main surface of the elastic substrate; A film member provided on at least one of the elastic substrate side and the side opposite to the elastic substrate with respect to the protective member, The film member has an appearance that irreversibly changes when stretched in the length direction.

[0120] <2> the film member changes from a transparent state to an opaque state when stretched in the longitudinal direction; <1> The stretchable wiring board according to claim 1.

[0121] <3> The film member is made of a resin that changes from an amorphous state to a crystalline state when the film member is stretched in the length direction. <2> The stretchable wiring board according to claim 1.

[0122] <4> The constituent material of the film member is polyethylene. <3> The stretchable wiring board according to claim 1.

[0123] <5> The film member is provided with a cut that can be broken when stretched in the length direction. <1> ~ <4> The stretchable wiring board according to any one of the preceding claims.

[0124] <6> The cut is provided along the width direction. <5> The stretchable wiring board according to claim 1.

[0125] <7> The film member is made of a non-elastic resin. <5> or <6> The stretchable wiring board according to claim 1.

[0126] <8> The constituent material of the film member is at least one of polyethylene terephthalate and polyimide. <7> The stretchable wiring board according to claim 1.

[0127] <9> The stretchable substrate has a narrow portion having a minimum cross-sectional area when viewed in a cross section perpendicular to the longitudinal direction, The film member is provided at a position overlapping the narrow portion when viewed from the thickness direction. <1> ~ <8> The stretchable wiring board according to any one of the preceding claims.

[0128] <10> The film member is provided on the opposite side of the protective member to the stretchable substrate. <1> ~ <9> The stretchable wiring board according to any one of the preceding claims. [Explanation of symbols]

[0129] 1A, 1B Stretchable wiring board 10A elastic base material 10Aa First main surface 10Ab Second main surface 11A Narrow part 20A Wiring material 21Aa, 21Ab stretchable wiring 30 Electronic Components 40A Protective material 40Aa 1st protection part 40Ab 2nd Protection Department 50A, 50B Film material 51 Cut 52 Break point D1 Distance between notches in the length direction D2 Dimension of the notch in the width direction D3 Distance between notches in width direction L Length direction T thickness direction W Width direction

Claims

1. An elastic substrate having a first main surface and a second main surface opposed to each other in a thickness direction; A wiring member comprising at least one elastic wiring provided on at least the first main surface side of the elastic base material and extending in a surface direction including a length direction perpendicular to the thickness direction and a width direction perpendicular to the thickness direction and the length direction; A protective member covering at least one of the first main surface and the second main surface of the stretchable substrate; A film member provided on at least one of the elastic substrate side and the opposite side to the elastic substrate with respect to the protective member, The film member is provided with a notch that can be broken when stretched in the length direction, The film member has an appearance that irreversibly changes when stretched in the length direction.

2. An elastic substrate having a first principal surface and a second principal surface opposed to each other in a thickness direction; A wiring member comprising at least one elastic wiring provided on at least the first main surface side of the elastic base material and extending in a surface direction including a length direction perpendicular to the thickness direction and a width direction perpendicular to the thickness direction and the length direction; A protective member covering at least one of the first main surface and the second main surface of the stretchable substrate; A film member provided on at least one of the elastic substrate side and the opposite side to the elastic substrate with respect to the protective member, The stretchable substrate has a narrow portion having a minimum cross-sectional area when viewed in a cross section perpendicular to the longitudinal direction, the film member is provided at a position overlapping the narrow portion when viewed from the thickness direction, The film member has an appearance that irreversibly changes when stretched in the length direction.

3. The stretchable wiring board according to claim 1 or 2, wherein the film member changes from a transparent state to an opaque state when stretched in the length direction.

4. The stretchable wiring board according to claim 3 , wherein the film member is made of a resin that changes from an amorphous state to a crystalline state when the film member is stretched in the length direction.

5. The stretchable wiring board according to claim 4 , wherein a constituent material of the film member is polyethylene.

6. The stretchable wiring board according to claim 1 , wherein the cuts are provided along the width direction.

7. The stretchable wiring board according to claim 1 or 6, wherein the film member is made of a non-stretchable resin.

8. The stretchable wiring board according to claim 7 , wherein a constituent material of the film member is at least one of polyethylene terephthalate and polyimide.

9. The stretchable substrate has a narrow portion having a minimum cross-sectional area when viewed in a cross section perpendicular to the longitudinal direction, The stretchable wiring board according to claim 1 , wherein the film member is provided at a position overlapping the narrow portion when viewed in the thickness direction.

10. The stretchable wiring board according to claim 1 or 2, wherein the film member is provided on the protective member opposite to the stretchable base material.

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