JP7119406B2 - Stretchable wiring board and manufacturing method thereof - Google Patents

Description

TECHNICAL FIELD The present disclosure relates to a stretchable wiring board having a stretchable base material and wiring.

In recent years, stretchable electronics (also referred to as stretchable electronics) have attracted attention, and stretchable wiring substrates have been actively developed. As one method for obtaining a stretchable wiring board, Patent Document 1 discloses stretching a stretchable base material in advance, placing a metal thin film on the stretched base material, and then relaxing the base material. A method has been proposed to do so.

Japanese Patent Application Laid-Open No. 2007-281406

In the method for producing a stretchable wiring board described above, when the base material is contracted by relaxing the base material, the thin metal film deforms into a bellows shape, and the peaks and valleys are formed along the in-plane direction of the base material. It has a bellows shape that appears repeatedly. When the base material is stretched, the metal thin film having the accordion-shaped part can follow the elongation of the base material by expanding the accordion-shaped part in the in-plane direction. Therefore, in such an elastic wiring board, it is possible to suppress the change in the resistance value of the metal thin film due to the expansion and contraction of the base material.

On the other hand, in the method for manufacturing an elastic wiring board described above, when the metal thin film deforms into a bellows-like shape, it may be caused by variations in elongation of the base material during elongation, differences in the distribution density of the metal thin film on the base material, and the like. , the degree of deformation varies depending on the position. If there is variation in the degree of deformation of the metal thin film, the degree of bending or bending occurring in the metal thin film may locally increase. At locations where the metal thin film is bent or bent locally to a large extent, stress is concentrated and damage such as breakage occurs, and resistance increases when the elastic wiring board is repeatedly stretched and contracted. .

The present disclosure has been made in view of the above problems, and an object of the present disclosure is to provide an elastic wiring board capable of suppressing damage such as bending of wiring and an increase in the resistance value of wiring.

In order to achieve the above object, the present disclosure has a first wiring, an interlayer insulating layer, and a second wiring in this order on a first surface of a base material having stretchability, and the first wiring and At least one of the second wirings has a bellows-shaped portion in which peaks and valleys in the normal direction of the first surface of the base material repeatedly appear along the in-plane direction of the first surface of the base material. and the elastic wiring board, wherein the Young's modulus of the interlayer insulation layer is smaller than the Young's modulus of the first wiring and the second wiring.

Further, the present disclosure includes a preparation step of preparing a laminate having a first wiring, an interlayer insulating layer, and a second wiring in this order, and applying a tensile stress to a stretchable base material to extend the base material. a wiring arrangement step of arranging the first wiring side surface of the laminate on the first surface side of the base material in an extended state; and the first surface side of the base material, the base material It is difficult to arrange the hard-to-stretch part on the second surface side opposite to the first surface, or inside the base material and in the connection area where the connection part of the first wiring or the second wiring is arranged. and a relaxing step of removing the tensile stress from the base material. The peaks and valleys in the normal direction of the base material have bellows-shaped portions repeatedly appearing along the in-plane direction of the first surface of the base material, and the Young's modulus of the interlayer insulating layer is higher than the Young's modulus of the wiring. and the Young's modulus of the difficult-to-stretch portion is greater than that of the substrate and equal to or higher than that of the interlayer insulating layer.

Advantageous Effects of Invention According to the present disclosure, it is possible to suppress damage such as bending of wiring and an increase in resistance of wiring.

1A and 1B are a schematic plan view and a cross-sectional view showing an example of an elastic wiring board of the present disclosure; 3A and 3B are a schematic plan view and a cross-sectional view showing another example of the stretchable wiring board of the present disclosure; FIG. It is process drawing which shows an example of the manufacturing method of the elastic wiring board of this indication. 3A and 3B are a schematic plan view and a cross-sectional view showing another example of the stretchable wiring board of the present disclosure; FIG. FIG. 4 is a schematic cross-sectional view showing another example of the stretchable wiring board of the present disclosure; 3A and 3B are a schematic plan view and a cross-sectional view showing another example of the stretchable wiring board of the present disclosure; FIG. 3A and 3B are a schematic plan view and a cross-sectional view showing another example of the stretchable wiring board of the present disclosure; FIG. 3A and 3B are a schematic plan view and a cross-sectional view showing another example of the stretchable wiring board of the present disclosure; FIG. FIG. 4 is a schematic cross-sectional view showing another example of the stretchable wiring board of the present disclosure; FIG. 4 is a schematic cross-sectional view showing another example of the stretchable wiring board of the present disclosure; FIG. 4 is a schematic cross-sectional view showing another example of the stretchable wiring board of the present disclosure; 3A and 3B are a schematic plan view and a cross-sectional view showing another example of the stretchable wiring board of the present disclosure; FIG. 3A and 3B are a schematic plan view and a cross-sectional view showing another example of the stretchable wiring board of the present disclosure; FIG. 3A and 3B are a schematic plan view and a cross-sectional view showing another example of the stretchable wiring board of the present disclosure; FIG. 3A and 3B are a schematic plan view and a cross-sectional view showing another example of the stretchable wiring board of the present disclosure; FIG. FIG. 4 is a schematic cross-sectional view showing another example of the stretchable wiring board of the present disclosure; FIG. 4 is a schematic cross-sectional view showing another example of the stretchable wiring board of the present disclosure; FIG. 4 is a schematic cross-sectional view showing another example of the stretchable wiring board of the present disclosure; FIG. 4 is a schematic cross-sectional view showing another example of the stretchable wiring board of the present disclosure; FIG. 4 is a schematic cross-sectional view showing another example of the stretchable wiring board of the present disclosure; FIG. 4 is a schematic plan view showing another example of the stretchable wiring board of the present disclosure; FIG. 4 is a schematic cross-sectional view showing another example of the stretchable wiring board of the present disclosure; FIG. 4 is a schematic cross-sectional view showing another example of the stretchable wiring board of the present disclosure; FIG. 4 is a schematic cross-sectional view showing another example of the stretchable wiring board of the present disclosure; FIG. 4 is a schematic plan view showing another example of the stretchable wiring board of the present disclosure; 4A to 4C are process diagrams showing another example of the method for manufacturing the stretchable wiring board of the present disclosure; 4A to 4C are process diagrams showing another example of the method for manufacturing the stretchable wiring board of the present disclosure; 4A to 4C are process diagrams showing another example of the method for manufacturing the stretchable wiring board of the present disclosure; 4A to 4C are process diagrams showing another example of the method for manufacturing the stretchable wiring board of the present disclosure;

Hereinafter, the stretchable wiring board of the present disclosure and the method for manufacturing the same will be described in detail.

A. Stretchable Wiring Board The stretchable wiring board of the present disclosure has a first wiring, an interlayer insulating layer, and a second wiring in this order on a first surface of a base material having stretchability, and the first wiring and at least one of the second wiring has a bellows-shaped portion in which peaks and valleys in the normal direction of the first surface of the base material repeatedly appear along the in-plane direction of the first surface of the base material. and the Young's modulus of the interlayer insulating layer is smaller than the Young's moduli of the first wiring and the second wiring.

Here, the term “stretchability” refers to the property of being able to stretch and contract, that is, the property of being able to stretch from a normal non-stretched state and recovering when released from this stretched state. The non-stretched state is the state when no tensile stress is applied. Elasticity is also called stretchable.

A stretchable wiring board of the present disclosure will be described with reference to the drawings. In the drawings referred to in the present disclosure, the same parts or parts having similar functions are denoted by the same reference numerals or similar reference numerals, and repeated description thereof may be omitted.

1(a) and 1(b) are a schematic plan view and a cross-sectional view showing an example of an elastic wiring board of the present disclosure, and FIG. 1(b) is a cross-sectional view taken along the line AA in FIG. 1(a). be. An elastic wiring board 1 illustrated in FIGS. 1A and 1B has a first wiring 3, an interlayer insulating layer 4, and a second wiring 5 on a first surface 2a of a base material 2 having elasticity. , in this order. The Young's modulus of interlayer insulating layer 4 is smaller than the Young's modulus of first wiring 3 and second wiring 5 . In this example, the first wiring 3 and the second wiring 5 extend in directions parallel to each other, and the interlayer insulating layer 4 is located on the entire surface of the substrate 2 on the side of the first surface 2a. In addition, the elastic wiring board 1 can have a supporting base material 7 between the base material 2 and the first wirings 3 and can have an adhesive layer 8 between the base material 2 and the supporting base material 7 .

In the elastic wiring board 1 shown in FIGS. 1(a) and 1(b) , the first wiring 3, the interlayer insulating layer 4 and the second wiring 5 are arranged on the ridges 31 in the normal direction of the first surface 2a of the substrate 2. , 33 , 35 , 37 and troughs 32 , 34 , 36 , 38 repeatedly appear along the in-plane direction of the first surface 2 a of the base material 2 . In FIGS. 1A and 1B, a peak portion 31 is a peak portion appearing on the surface of the second wiring 5 opposite to the surface facing the interlayer insulating layer 4 , and a peak portion 33 is a peak portion appearing on the surface of the second wiring 5 . , and a peak appearing on the surface of the interlayer insulating layer 4 on the second wiring 5 side. and a peak appearing on the surface of the first wiring 3 facing the interlayer insulating layer 4 . A peak 37 appears on the surface of the first wiring 3 facing the substrate 2 . The valley portion 32 appears on the surface of the second wiring 5 opposite to the interlayer insulating layer 4 side, and the valley portion 34 appears on the surface of the second wiring 5 on the interlayer insulating layer 4 side. The valley portion appears on the surface of the interlayer insulating layer 4 facing the second wiring 5, and the valley portion 36 appears on the surface of the interlayer insulating layer 4 facing the first wiring 3, and the first wiring. The valley portion 38 is a valley portion appearing on the surface of the first wiring 3 on the base material 2 side.

2(a) to (c) are schematic plan views and cross-sectional views showing other examples of the stretchable wiring board of the present disclosure, and FIG. 2(b) is a cross-sectional view taken along line AA in FIG. 2(a). FIG. 2(c) is a cross-sectional view taken along line BB of FIG. 2(a). The stretchable wiring board 1 illustrated in FIGS. 2A to 2C has a first wiring 3, an interlayer insulating layer 4, and a second wiring 5 on a first surface 2a of a base material 2 having stretchability. , in this order. The Young's modulus of interlayer insulating layer 4 is smaller than the Young's modulus of first wiring 3 and second wiring 5 . In this example, the first wiring 3 and the second wiring 5 extend in directions perpendicular to each other, and the interlayer insulating layer 4 is located at least in the intersection region 20 where the first wiring 3 and the second wiring 5 intersect. there is

In the stretchable wiring board 1 shown in FIGS. 2A and 2B , the first wiring 3 has peaks and valleys in the normal direction of the first surface 2 a of the base material 2 . It has a bellows-shaped portion repeatedly appearing along the in-plane direction of 2a.

3(a) to 3(e) are process diagrams showing an example of the method for manufacturing the stretchable wiring board of the present disclosure. First, as shown in FIG. 3(a), the first wiring 3, the interlayer insulating layer 4 and the second wiring 5 are arranged in order on one surface of the supporting substrate 7 to fabricate a laminate. Further, as shown in FIGS. 3(b) to 3(c), the stretchable base material 2 is stretched. Next, as shown in FIG. 3D, in a state where the base material 2 is stretched, a surface of the support base material 7 side of the laminate is applied to the first surface 2a of the base material 2 via the adhesive layer 8. are pasted together. Subsequently, as shown in FIG. 3(e), the tensile stress of the substrate 2 is removed. At this time, as the elastic base material 2 shrinks, the first surface 2a of the base material 2, the first wiring 3, the interlayer insulating layer 4, and the second wiring 5 are deformed into a bellows-shaped portion. will have Similarly, the supporting substrate 7 and the adhesive layer 8 also have a bellows-shaped portion.

In addition, hereinafter, the direction in which peaks and valleys of the bellows-shaped portion appear repeatedly may be referred to as a first direction. In FIGS. 1A and 1B, the first wiring 3 and the second wiring 5 extend parallel to the first direction D1. In addition, in FIGS. 2A and 2B, the first wiring 3 extends parallel to the first direction D1.

In the present disclosure, at least one of the first wiring and the second wiring has a bellows-shaped portion, and the stretchable wiring board usually has the bellows-shaped portion on the first surface side of the substrate. Since the base material has stretchability, when the stretchable wiring board is stretched, the base material can be stretched by elastic deformation. Here, if the wiring is similarly stretched by elastic deformation, the total length of the wiring increases and the cross-sectional area of the wiring decreases, so the resistance value of the wiring increases. Also, it is conceivable that damage such as cracks may occur in the wiring due to elastic deformation of the wiring. In contrast, in the present disclosure, at least one of the first wiring and the second wiring has a bellows-shaped portion, and the stretchable wiring board usually has the bellows-shaped portion on the first surface side of the base material. Therefore, when the substrate expands, the first wiring and the second wiring follow the expansion of the substrate by deforming to reduce the undulations of the accordion-shaped portion, that is, by eliminating the accordion-shaped portion. can be done. Therefore, it is possible to suppress an increase in the total length of the first wiring and the second wiring and a decrease in the cross-sectional areas of the first wiring and the second wiring due to the extension of the base material. Thereby, it is possible to suppress an increase in the resistance values of the first wiring and the second wiring due to the extension of the stretchable wiring board. Moreover, it is possible to suppress the occurrence of damage such as cracks in the first wiring and the second wiring.

By the way, in the method of manufacturing a stretchable wiring board, when the wiring is deformed into a bellows shape, the degree of deformation is caused by variations in elongation of the base material during elongation, differences in distribution density of the wiring on the base material, and the like. , and it varies depending on the position. If there is variation in the degree of deformation of the wiring, the degree of bending or bending occurring in the wiring may locally increase. In particular, when the first wiring, the interlayer insulating layer and the second wiring are laminated on the first surface of the base material, the thickness of the entire stretchable wiring board increases. As compared with , the wiring is less likely to deform into a bellows shape, so the bellows-shaped portion is more likely to be distorted, and the degree of bending or bending occurring in the wiring tends to increase locally. In particular, the farther away the wiring is from the stretchable base material, the less likely the second wiring is to deform into a bellows shape. The second wiring tends to be easily distorted, and the degree of bending or bending that occurs in the second wiring tends to increase locally. Stress concentrates at locations where the wiring is locally bent or curved to a large extent. Also, in general, an elastomer is used for the base material, and a metal, an alloy, or the like is used for the wiring, so that the Young's modulus of the wiring is much larger than that of the base material. That is, the wiring is harder than the base material and is less deformable. Therefore, stress is likely to concentrate at locations where the degree of bending or bending that occurs in the wiring is locally large. At a portion of the wiring where stress is concentrated, damage such as folding may occur, and the resistance value may increase when the stretchable wiring board is repeatedly stretched and stretched.

In contrast, according to the present disclosure, between the first wiring and the second wiring, the Young's modulus is smaller than that of the first wiring and the second wiring, that is, it is softer and more easily deformed than the first wiring and the second wiring. The presence of the interlayer insulating layer can disperse the stress. Therefore, even if the degree of bending or bending that occurs in the first wiring and the second wiring is locally increased, stress concentration can be reduced at locations where the degree of bending or bending is locally large. . As a result, it is possible to prevent the first wiring and the second wiring from being damaged and the resistance values of the first wiring and the second wiring from increasing when the stretchable wiring board is repeatedly stretched and contracted.

In addition, when the first wiring, the interlayer insulating layer and the second wiring are laminated on the first surface of the base material, the thickness of the entire elastic wiring board increases. Compared to , the wiring is less likely to deform into a bellows shape. In particular, the farther away the wiring is from the stretchable base material, the less likely the second wiring is to deform into a bellows shape. Therefore, since the bellows-shaped portion is less likely to occur, the stretchable wiring board is less likely to restore after being stretched, and the stretchability of the stretchable wiring board is reduced.

In contrast, according to the present disclosure, between the first wiring and the second wiring, the Young's modulus is smaller than that of the first wiring and the second wiring, that is, it is softer and more easily deformed than the first wiring and the second wiring. Due to the presence of the interlayer insulating layer, the bellows-shaped portion can be easily generated in the second wiring. Therefore, a stretchable wiring board having good stretchability can be obtained.

The stretchable wiring board of the present disclosure has at least a stretchable base material, first wiring, an interlayer insulating layer, and second wiring. Hereinafter, each configuration of the stretchable wiring board of the present disclosure will be described.

1. Interlayer insulating layer The interlayer insulating layer in the present disclosure is a member positioned between the first wiring and the second wiring to insulate the first wiring and the second wiring.

The Young's modulus of the interlayer insulating layer is smaller than the Young's moduli of the first wiring and the second wiring. Moreover, the Young's modulus of the interlayer insulating layer is preferably higher than that of the stretchable substrate. That is, the interlayer insulating layer preferably has a Young's modulus intermediate between that of the first wiring and second wiring and that of the substrate. Between the first wiring and the second wiring, it has an intermediate Young's modulus between the first wiring and the second wiring and the base material, that is, it is softer and more deformable than the first wiring and the second wiring, and more flexible than the base material. This is because stress concentration can be reduced by locating the hard and hard-to-deform interlayer insulating layer. In addition, the Young's modulus of the interlayer insulating layer is larger than the Young's modulus of the stretchable base material, that is, the interlayer insulating layer is harder than the base material and is less deformable, so that the insulating properties of the interlayer insulating layer are maintained. can do.

In addition, as will be described later, when the stretchable wiring board of the present disclosure has a supporting base material between the base material and the first wiring, the Young's modulus of the interlayer insulating layer is higher than that of the supporting base material. It may be smaller, may be the same as the Young's modulus of the supporting substrate, or may be larger than the Young's modulus of the supporting substrate. Among them, the Young's modulus of the interlayer insulating layer is preferably smaller than that of the supporting substrate. Interlayer insulation between the first wiring and the second wiring, which has a Young's modulus smaller than that of the first wiring, the second wiring and the supporting substrate, that is, is softer and deformable than the first wiring, the second wiring and the supporting substrate. This is because the stress concentration can be reduced by locating the layers.

Specifically, the Young's modulus of the interlayer insulating layer can be less than 1 times the Young's modulus of the first wiring and/or the second wiring, preferably 0.1 times or less, and more preferably 0.1 times. 05 times or less. The Young's modulus of the interlayer insulating layer can be 0.001 times or more, preferably 0.01 times or more, that of the first wiring and/or the second wiring.
In addition, the Young's modulus of the interlayer insulating layer can be more than 1 times, preferably 1.1 times or more, more preferably 2 times or more the Young's modulus of the stretchable base material. The Young's modulus of the interlayer insulating layer can be 100 times or less, preferably 10 times or less, that of the stretchable base material.
This is because if the Young's modulus of the interlayer insulating layer is too small or too large, it may become difficult to reduce the stress concentration. Further, if the Young's modulus of the interlayer insulating layer is too small, the insulating properties of the interlayer insulating layer may be impaired when the stretchable wiring board is repeatedly stretched.

Also, the Young's modulus of the interlayer insulating layer can be, for example, 1 GPa or less, preferably 100 MPa or less, and more preferably 10 MPa or less. Also, the Young's modulus of the interlayer insulating layer can be, for example, 10 kPa or more, preferably 1 MPa or more. This is because if the Young's modulus of the interlayer insulating layer is too small or too large, it may become difficult to reduce the stress concentration. Further, if the Young's modulus of the interlayer insulating layer is too small, the insulating properties of the interlayer insulating layer may be impaired when the stretchable wiring board is repeatedly stretched.

The Young's modulus of each member is the Young's modulus at room temperature.
As a method for measuring the Young's modulus of the interlayer insulating layer, a measuring method by a nanoindition method in compliance with ISO14577 can be adopted. Specifically, the Young's modulus of the interlayer insulating layer can be measured using a nanoindenter. Moreover, as a method of obtaining the Young's modulus of the interlayer insulating layer, a method of carrying out a tensile test using a sample of the interlayer insulating layer can also be adopted. As a method of preparing a sample of the interlayer insulation layer, there is a method of taking out a part of the interlayer insulation layer from the elastic wiring board as a sample, and a method of taking out a part of the interlayer insulation layer as a sample before forming the elastic wiring board. is mentioned. In addition, as a method of obtaining the Young's modulus of the interlayer insulating layer, it is also possible to adopt a method of analyzing the material constituting the interlayer insulating layer and obtaining the Young's modulus of the interlayer insulating layer based on an existing material database. .
The method for obtaining the Young's modulus of the first wiring, the second wiring, the elastic base material, and the supporting base material is the same as the method for obtaining the Young's modulus of the interlayer insulating layer.

The interlayer insulating layer can have a bellows-shaped portion. The bellows-shaped portion of the interlayer insulating layer can be the same as the bellows-shaped portion of the first wiring and the second wiring, which will be described later.

The material of the interlayer insulating layer may be any material as long as it has insulating properties and the above Young's modulus. For example, it may or may not have elasticity.

Examples of non-stretchable materials used for the interlayer insulating layer include resins. As the resin, a resin that is generally used for an interlayer insulating layer can be used, and for example, any of thermoplastic resin, thermosetting resin, photo-setting resin, and the like can be used. Specific examples include polyimide resins, acrylic resins, urethane resins, and silicone resins. Also, the Young's modulus of the interlayer insulating layer can be adjusted by adjusting the molecular weight, structure, cross-linking density, glass transition temperature, etc. of the resin, for example. Moreover, when an interlayer insulation layer contains resin, a resin base material can also be used as an interlayer insulation layer.

The stretchability of the material having stretchability used for the interlayer insulating layer can be the same as the stretchability of the base material having stretchability described later.
Examples of stretchable materials used for the interlayer insulating layer include elastomers. As the elastomer, general thermoplastic elastomers and thermosetting elastomers can be used, and specific examples include styrene elastomers, olefin elastomers, silicone elastomers, urethane elastomers, amide elastomers, silicone rubbers, urethane elastomers. rubber, fluororubber, polybutadiene, polyisobutylene, polystyrene butadiene, polychloroprene, and the like. Moreover, silicone resin and urethane resin can also be used as the material.

The interlayer insulating layer may be positioned at least in the intersection region where the first wiring and the second wiring intersect. It may be partially located on one side. For example, in FIGS. 1A and 1B, the interlayer insulating layer 4 is located on the entire surface of the substrate 2 on the side of the first surface 2a. Further, for example, in FIGS. 2A and 2B, the interlayer insulating layer 4 is partially located on the first surface 2a side of the base material 2 so as to be located at least in the intersection region 20 .

Further, the interlayer insulating layer may be located in the first wiring region where the first wiring is located and the second wiring region where the second wiring is located. Since the interlayer insulating layer is positioned in the first wiring region and the second wiring region, it is possible to suppress the first wiring and the second wiring from being damaged such as bending.

In addition, when the stretchable wiring board of the present disclosure has a functional member region adjacent to the first wiring region and/or the second wiring region and on which a functional member is mounted, the interlayer insulating layer and/or may be positioned continuously with the second wiring region and the functional member region adjacent to the first wiring region and/or the second wiring region. For example, in FIGS. 4A and 4B, the interlayer insulating layer 4 is continuous with the second wiring region 22 and the functional member region 23 adjacent to the second wiring region 22 and on which the functional member 6 is mounted. It is located.
Here, in the stretchable wiring board, the height of the ridges of the bellows-shaped portion is caused by variations in the thickness of the base material, differences in the distribution density of the first wiring and the second wiring provided on the base material, and the like. can be locally large. For example, when a functional member is connected to the second wiring, a large ridge may occur in the second wiring near the boundary between the second wiring and the functional member. In this case, a large stress is applied to the connecting portion between the second wiring and the functional member, and the connecting portion may be broken.
On the other hand, since the interlayer insulating layer is continuously positioned in the second wiring region and the functional member region, the second wiring has a large peak in the vicinity of the boundary between the second wiring and the functional member. can be prevented from occurring. Thereby, it is possible to suppress breakage of the connecting portion between the second wiring and the functional member.
Further, when the functional member is connected to the first wiring, the inter-layer insulating layer is continuously positioned between the first wiring region and the functional member region, thereby connecting the first wiring and the functional member. , it is possible to suppress the occurrence of large ridges on the first wiring in the vicinity of the boundary between the . Thereby, it is possible to suppress breakage of the connecting portion between the first wiring and the functional member.

When the interlayer insulation layer is continuously positioned between the first wiring region and/or the second wiring region and the functional member region adjacent to the first wiring region and/or the second wiring region, the interlayer insulation The layer may be positioned continuously with at least the first wiring region and/or the second wiring region and the functional member region adjacent to the first wiring region and/or the second wiring region. , may be located in the entire functional member region, or may be partially located in the functional member region.

The thickness of the interlayer insulating layer may be any thickness that has insulating properties and can withstand expansion and contraction, and is appropriately selected according to the material of the interlayer insulating layer. The thickness of the interlayer insulating layer can be, for example, 0.1 μm or more, preferably 1 μm or more, and more preferably 10 μm or more. Also, the thickness of the interlayer insulating layer can be, for example, 1 mm or less, preferably 500 μm or less, and more preferably 100 μm or less. If the thickness of the interlayer insulating layer is too thin, the insulating properties may be poor, and the effect of reducing stress concentration may not be sufficiently obtained. Also, if the interlayer insulating layer is too thick, even if the Young's modulus satisfies the above relationship, the bending rigidity of the interlayer insulating layer increases, which may make it difficult to reduce stress concentration. The bending rigidity is represented by the product of the area moment of inertia of the target member and the Young's modulus of the material of the target member.

As a method for forming the interlayer insulating layer, a general method for forming an interlayer insulating layer used for wiring substrates can be applied. Moreover, when forming an interlayer insulation layer partially, the photolithography method, the printing method, etc. can be used, for example.

2. First Wiring and Second Wiring The first wiring in the present disclosure is a member positioned between the base material and the interlayer insulating layer and having conductivity. Further, the second wiring in the present disclosure is a member that is located on the surface of the interlayer insulating layer opposite to the surface on the side of the first wiring and has conductivity. At least one of the first wiring and the second wiring has a bellows-shaped portion in which peaks and valleys in the normal direction of the first surface of the base material repeatedly appear along the in-plane direction of the first surface of the base material.

In this specification, for the sake of convenience, the wiring located on the substrate side surface of the interlayer insulating layer is referred to as the first wiring, and the wiring located on the surface opposite to the substrate side surface of the interlayer insulating layer is referred to as the second wiring. called wiring.
In addition, the second wiring is a wiring located on the surface of the interlayer insulating layer opposite to the base material side surface, but if it is insulated from the first wiring, the second wiring is located on the surface of the interlayer insulating layer on the base material side. may be located on the same plane as the first wiring as well as on the opposite side. For example, as shown in FIGS. 1A and 1B, when the interlayer insulating layer 4 is located on the entire surface of the substrate 2 on the side of the first surface 2a, the second wiring 5 is formed on the interlayer insulating layer 4. It is positioned on the surface opposite to the surface on the substrate 2 side. On the other hand, as shown in FIGS. 2A to 2C, when the interlayer insulating layer 4 is partially located on the first surface 2a side of the base material 2, the second wiring 5 is formed on the interlayer insulating layer 4 may be located on the same plane as the first wiring 3, that is, on the support substrate 7, not only on the surface opposite to the surface on the substrate 2 side.

The stretchable wiring board of the present disclosure may have a plurality of first wirings. Also, the stretchable wiring board may have first wiring extending in the first direction, or may have first wiring extending in a direction different from the first direction. In the example shown in FIGS. 1(a) and 1(b), the first wiring 3 has peaks 31, 33, 35, and 37 and valleys 32, 34, 36, and 38 of the bellows-shaped portion 30 appearing repeatedly in a first direction. It extends parallel to D1.

Similarly, the stretchable wiring board of the present disclosure may have a plurality of second wirings. The stretchable wiring board may have second wiring extending in the first direction, or may have second wiring extending in a direction different from the first direction. In the example shown in FIGS. 1(a) and 1(b), the second wiring 5 is configured such that the peaks 31, 33, 35, 37 and the valleys 32, 34, 36, 38 of the bellows-shaped portion 30 appear repeatedly in a first direction. It extends parallel to D1. In addition, in the examples shown in FIGS. 2A and 2B, the second wiring 5 extends in a direction perpendicular to the first direction D1.

Also, in plan view, the first wiring and the second wiring may be parallel to each other or may cross each other.

At least one of the first wiring and the second wiring may have a bellows-shaped portion. For example, the first wiring may have a bellows-shaped portion, and the second wiring may have a bellows-shaped portion. Alternatively, the first wiring and the second wiring may have a bellows-shaped portion. Further, when the first wiring has the bellows-shaped portion, the entire first wiring may have the bellows-shaped portion, or a part of the first wiring may have the bellows-shaped portion. Similarly, when the second wiring has a bellows-shaped portion, all of the second wiring may have the bellows-shaped portion, or a part of the second wiring may have the bellows-shaped portion.

The amplitude of the bellows-shaped portion can be, for example, 1 μm or more, preferably 10 μm or more, more preferably 50 μm or more, and still more preferably 100 μm or more. Further, the amplitude of the accordion-shaped portion can be, for example, 500 μm or less, preferably 400 μm or less, and more preferably 300 μm or less. By setting the amplitude of the accordion-shaped portion within the above range, the first wiring and the second wiring are easily deformed following the extension of the base material.

Note that the amplitude of the bellows-shaped portion is between adjacent peaks and valleys, as indicated by symbols S1, S2, S3, and S4 shown in FIG. Distance. The amplitude S1 is the amplitude in the normal direction of the substrate of the bellows-shaped portion of the surface of the first wiring 3 on the substrate 2 side. The amplitude S2 is the amplitude of the accordion-shaped portion of the surface of the first wiring 3 on the side of the interlayer insulating layer 4 in the normal direction of the substrate. The amplitude S3 is the amplitude of the accordion-shaped portion of the surface of the second wiring 5 on the side of the interlayer insulating layer 4 in the normal direction of the substrate. The amplitude S4 is the amplitude in the normal direction of the substrate of the bellows-shaped portion of the surface of the second wiring 5 opposite to the surface facing the interlayer insulating layer 4 .

The amplitude of the bellows-shaped portion is obtained, for example, by measuring the distance between adjacent peaks and troughs in the normal direction of the first surface of the substrate over a certain range in the first direction, and averaging them. It is calculated by asking. The certain range in the first direction can be 10 mm, for example. As a measuring instrument for measuring the distance between adjacent peaks and valleys, a non-contact measuring instrument using a laser microscope or the like may be used, or a contact measuring instrument may be used. Alternatively, the distance between adjacent peaks and valleys may be measured based on an image such as a cross-sectional photograph.

The period of the bellows-shaped portion can be, for example, 10 μm or more, preferably 50 μm or more, and more preferably 100 μm or more. Also, the period of the accordion-shaped portion can be, for example, 1000 μm or less, preferably 750 μm or less, and more preferably 500 μm or less. By setting the period of the accordion-shaped portion within the above range, the first wiring and the second wiring are easily deformed following the extension of the base material.

The period of the bellows-shaped portion is the interval between adjacent peaks in the first direction D1, as indicated by symbol F in FIG.

The period of the bellows-shaped portion is calculated, for example, by measuring the interval between adjacent peaks in the first direction over a certain range in the first direction and averaging the intervals. The certain range in the first direction can be 10 mm, for example. A non-contact type measuring device using a laser microscope or the like may be used as a measuring device for measuring the interval between adjacent peak portions, or a contact type measuring device may be used. Alternatively, the interval between adjacent peaks may be measured based on an image such as a cross-sectional photograph.

The Young's modulus of the first wiring and the second wiring is higher than the Young's modulus of the interlayer insulating layer, and can be, for example, 100 MPa or more, preferably 200 MPa or more. Also, the Young's modulus of the first wiring and the second wiring can be, for example, 300 GPa or less, preferably 200 GPa or less, and more preferably 100 GPa or less. When the Young's moduli of the first wiring and the second wiring are within the above range, stress concentration is likely to occur. is arranged, it is possible to reduce the stress concentration.
The method of determining the Young's modulus of the first wiring and the second wiring is the same as the method of determining the Young's modulus of the interlayer insulating layer.

Any material can be used for the first wiring and the second wiring as long as it can follow the expansion and contraction of the base material by utilizing the formation and elimination of the bellows-shaped portion. The materials of the first wiring and the second wiring may or may not themselves have elasticity.

Non-stretchable materials used for the first wiring and the second wiring include, for example, metals such as gold, silver, copper, aluminum, platinum, and chromium, and alloys containing these metals. When the material of the first wiring and the second wiring does not have elasticity, a metal film can be used as the first wiring and the second wiring.

The stretchability of the stretchable material used for the first wiring and the second wiring can be the same as the stretchability of the later-described stretchable base material.
Examples of stretchable materials used for the first wiring and the second wiring include a conductive composition containing conductive particles and an elastomer. That is, the wiring can include conductive particles and an elastomer. The conductive particles may be those that can be used for wiring, and examples thereof include particles of gold, silver, copper, nickel, palladium, platinum, carbon, and the like. Among them, silver particles are preferably used. As the elastomer, general thermoplastic elastomers and thermosetting elastomers can be used. Examples include styrene elastomer, acrylic elastomer, olefin elastomer, urethane elastomer, silicone rubber, urethane rubber, fluorine rubber, Examples include nitrile rubber, polybutadiene, and polychloroprene.

Among them, the first wiring is preferably a metal film.
Here, the “metal film” refers to a film made of metal or alloy. Metallic films do not include films containing, for example, conductive particles and elastomers.
If the first wiring contains conductive particles, the conductive particles may penetrate the interlayer insulating layer depending on the particle size, shape, etc. of the conductive particles, and the insulating properties of the interlayer insulating layer may be impaired. Since the first wiring is a metal film, the insulating property of the interlayer insulating layer can be maintained.

Also, the second wiring preferably contains conductive particles and an elastomer. As described above, since the second wiring is located farther from the base than the first wiring, it is difficult to deform into a bellows shape. This is because the second wiring can be easily deformed in accordance with . In addition, since the second wiring contains the conductive particles and the elastomer, resistance to deformation can be enhanced.

In addition, in the wiring containing the conductive particles and the elastomer, the distribution and shape of the conductive particles are adjusted so that the contact between the plurality of conductive particles is maintained even when deformation occurs. Thereby, the conductivity of the wiring can be maintained.

In addition, when the second wiring is located not only on the surface of the interlayer insulating layer opposite to the base material side but also on the same plane as the first wiring, the second wiring may be positioned on the interlayer insulating layer. and the portion located on the same plane as the first wiring may be configured integrally or may be configured separately. Note that "integrally" means that there is no interface between the portion of the second wiring located on the interlayer insulating layer and the portion of the second wiring located on the same plane as the first wiring.
For example, in FIGS. 2A to 2C, in the second wiring 5, the portion located on the interlayer insulating layer 4 and the portion located on the same plane as the first wiring 3 are integrated. It is In this case, the portion of second wiring 5 located on interlayer insulating layer 4 and the portion of second wiring 5 located on the same plane as first wiring 3 contain the same material.
6A to 6C, in the second wiring 5, the portion 5a located on the interlayer insulating layer 4 and the portion 5b located on the same plane as the first wiring 3 are separated. It is configured. In this case, in the second wiring 5, the portion 5a located on the interlayer insulating layer 4 and the portion 5b located on the same plane as the first wiring 3 may contain the same material, or may contain different materials. It may contain materials. 6(b) is a cross-sectional view taken along line AA of FIG. 6(a), and FIG. 6(c) is a cross-sectional view taken along line BB of FIG. 6(a).

When the portion of the second wiring located on the interlayer insulating layer and the portion of the second wiring located on the same plane as the first wiring contain different materials, the portion located on the interlayer insulating layer may preferably contains conductive particles and an elastomer. As described above, the portion of the second wiring located on the interlayer insulating layer is located farther from the substrate than the first wiring, and thus is less likely to deform into a bellows shape. This is because, by containing the conductive particles and the elastomer in the portion where the second wiring is located on the interlayer insulating layer, the portion located on the interlayer insulating layer of the second wiring can be easily deformed according to the expansion and contraction of the base material. Also, by containing the conductive particles and the elastomer in the portion of the second wiring located on the interlayer insulating layer, resistance to deformation can be enhanced.

In the above case, the portion of the second wiring located on the same plane as the first wiring may contain, for example, conductive particles and an elastomer, or may be a metal film. When the portion of the second wiring located on the same plane as the first wiring is a metal film, the first wiring and the portion of the second wiring located on the same plane as the first wiring are formed on the same plane. , can be formed simultaneously.

Further, the shape of the first wiring and the second wiring in a plan view is not particularly limited, but it is preferable that they are linear as illustrated in FIGS. 1(a) and 2(a). This is because the design of the stretchable wiring board is facilitated.

The thickness of the first wiring and the second wiring may be any thickness that can withstand expansion and contraction, and is appropriately selected according to the materials of the first wiring and the second wiring.
For example, when the material of the first wiring and the second wiring does not have stretchability, the thickness of the first wiring and the second wiring can be 25 nm or more, preferably 50 nm or more, and 100 nm or more. It is more preferable to have In this case, the thickness of the first wiring and the second wiring can be 10 μm or less, preferably 5 μm or less, and more preferably 1 μm or less.
Further, when the material of the first wiring and the second wiring has stretchability, the thickness of the first wiring and the second wiring can be 5 μm or more, preferably 10 μm or more, and preferably 20 μm or more. is more preferred. In this case, the thickness of the first wiring and the second wiring can be 60 μm or less, preferably 50 μm or less, and more preferably 40 μm or less.

The width of the first wiring and the second wiring can be, for example, 50 μm or more and can be 10 mm or less.

A method for forming the first wiring and the second wiring is appropriately selected according to the material and the like. When the material of the first wiring and the second wiring does not have stretchability, for example, a method of forming a metal film on a supporting substrate by a vapor deposition method, a sputtering method, or the like and then patterning the metal film by a photolithography method can be used. be done. Further, when the material of the first wiring and the second wiring has stretchability, for example, the conductive composition containing the above-described conductive particles and elastomer is printed in a pattern on the support substrate by a general printing method. method.

The stretchable wiring board of the present disclosure can have a connecting portion for the first wiring or the second wiring. The connection portion includes a connection portion between the first wiring and another member and a connection portion between the second wiring and another member. Examples of the connecting portion include a connecting portion between the first wiring and the second wiring, a connecting portion between the first wiring and the functional member, and a connecting portion between the second wiring and the functional member.

The connection portion between the first wiring and the second wiring can be, for example, similar to vias and through holes in a general wiring board.
A connecting portion between the first wiring and the second wiring can be positioned in a through hole provided in the interlayer insulating layer.
As the material for the connection portion between the first wiring and the second wiring, a material for vias in a general wiring substrate can be used, and for example, the material for the above-described first wiring and second wiring can be used. can.
The size of the connecting portion between the first wiring and the second wiring can be the same as the size of vias in a general wiring substrate.
Examples of the method for forming the connecting portion between the first wiring and the second wiring include a method of filling with a metal paste and a plating method.

The connecting portion between the first wiring and the functional member and the connecting portion between the second wiring and the functional member can be, for example, similar to the connection by surface mounting on a general circuit board.
Materials used for surface mounting on a general circuit board can be used as materials for the connecting portion between the first wiring and the functional member and the connecting portion between the second wiring and the functional member.

3. Base Material Having Elasticity The base material in the present disclosure is a plate-like member having elasticity. The substrate includes a first surface located on the side of the first wiring and the second wiring, and a second surface located on the opposite side of the first surface.

The base material has elasticity. An example of a parameter representing the stretchability of the base material is the recovery rate. The recovery rate of the substrate is 80% or more when released from the stretched state after being stretched to 50% (1.5 times the initial length) based on the normal state (non-stretched state). is preferred, 85% or more is more preferred, and 90% or more is even more preferred. Note that the upper limit of the restoration rate is 100%.
In addition, the recovery rate is obtained by preparing a test piece with a width of 25 mm, stretching the test piece by 50% and holding it for 1 hour, releasing the stretch and leaving it for 1 hour to restore it, and using the following calculation formula. can.
Restoration rate (%) = (Length immediately after stretching - Length after restoration) / (Length immediately after stretching - Length before stretching) x 100
It should be noted that the length immediately after stretching refers to the length in a state of being stretched by 50%.

Further, another example of the parameter representing the stretchability of the base material is the elongation rate. Preferably, the substrate can be stretched by 1% or more, more preferably by 20% or more, and even more preferably by 75% or more from an unstretched state without breaking. By using such a stretchable base material, the stretchable wiring board can have stretchability as a whole. Furthermore, the stretchable wiring board can be used in products and applications that require high stretchability, such as attachment to a part of the body such as a human arm. Generally, it is said that a product to be attached to a person's armpit should have a stretchability of 72% in the vertical direction and 27% in the horizontal direction. In addition, it is said that products that are attached to human knees, elbows, buttocks, ankles, and armpits must have elasticity of 26% or more and 42% or less in the vertical direction. In addition, it is said that less than 20% stretchability is required for products to be attached to other parts of the human body.

Moreover, it is preferable that the difference between the shape of the substrate in the non-stretched state and the shape of the substrate when it returns to the non-stretched state after being stretched from the non-stretched state is small. In addition, hereinafter, this difference may be referred to as shape change. The shape change of the base material can be, for example, 20% or less, more preferably 10% or less, and still more preferably 5% or less in terms of area ratio. By using a base material with small change in shape, the formation of the bellows-shaped portion is facilitated.

The Young's modulus of the substrate can be, for example, 10 MPa or less, preferably 1 MPa or less. Also, the Young's modulus of the substrate can be 1 kPa or more. By using a base material having such a Young's modulus, it is possible to impart stretchability to the entire stretchable wiring board.
The method for determining the Young's modulus of the substrate is the same as the method for determining the Young's modulus of the interlayer insulating layer.

The material of the base material may be any material as long as it has stretchability, and examples thereof include elastomers, which are appropriately selected according to the application of the stretchable wiring board. As the elastomer, general thermoplastic elastomers and thermosetting elastomers can be used. Specifically, styrene-based elastomers, olefin-based elastomers, urethane-based elastomers, amide-based elastomers, nitrile-based elastomers, and vinyl chloride-based elastomers can be used. , ester elastomer, 1,2-polybutadiene elastomer, fluorine elastomer, silicone rubber, urethane rubber, fluorine rubber, polybutadiene, polyisobutylene, polystyrene butadiene, polychloroprene, and the like. Considering mechanical strength and abrasion resistance, it is preferable to use a urethane-based elastomer. Also, the substrate may contain silicone. Silicone is excellent in heat resistance, chemical resistance, and flame retardancy, and is preferable as a material for the base material.

The thickness of the substrate is not particularly limited, but is appropriately selected according to the material of the substrate. It can also be 10 mm or less, preferably 3 mm or less, and more preferably 1 mm or less. By setting the thickness of the base material to the above value or more, the durability of the base material can be ensured. In addition, by setting the thickness of the base material to the above value or less, it is possible to secure wearing comfort of the stretchable wiring board. In addition, if the thickness of the base material is too thin, the stretchability of the base material may be impaired.

4. Difficult-to-stretch portion The stretchable wiring board of the present disclosure is located on the first surface side of the base material, the second surface side of the base material, or inside the base material, and the connection part of the first wiring or the second wiring is It is preferable to have a difficult-to-stretch portion positioned in the connecting region and having a Young's modulus greater than that of the base material and equal to or higher than that of the interlayer insulating layer.

Here, the "hardly stretchable part located on the first surface side of the base material" means that the difficultly stretchable part may be directly positioned on the first surface of the base material, and the difficultly stretchable part may be located on the first surface of the base material. may be located indirectly through other members.
In addition, the "hardly stretchable part located on the second surface side of the base material" can be the same as the difficultly stretchable part located on the first surface side of the base material.

7(a) and (b) are a schematic plan view and a cross-sectional view showing another example of the stretchable wiring board of the present disclosure, and FIG. 7(b) is a cross-sectional view taken along line CC of FIG. 7(a). is. As shown in FIGS. 7(a) and 7(b), the stretchable wiring board 1 has a difficult-to-stretch portion 11 located in the connection region 24 where the connection portions 9 of the first wirings 3 and the second wirings 5 are located. can be done. The Young's modulus of the hard-to-stretch portion 11 is greater than that of the base material 2 and equal to or higher than that of the interlayer insulating layer 4 . In FIGS. 7A and 7B , the difficult-to-stretch portion 11 is located in the connection region 24 and the region around the connection region 24 . In addition, the hard-to-stretch portion 11 is located on the first surface 2a side of the base material 2 and is located on the surface of the second wiring 5 opposite to the surface facing the interlayer insulating layer 4 and the first wiring of the interlayer insulating layer 4. It is located on the surface opposite to the surface on the 3 side. In addition, in FIG. 7A, part of the first wiring and the second wiring are indicated by broken lines.

8(a) to (d) are schematic plan views and cross-sectional views showing other examples of the stretchable wiring board of the present disclosure, and FIG. 8(b) omits the hard-to-stretch portion in FIG. 8(a). 8(c) is a sectional view taken along the line CC of FIG. 8(a), and FIG. 8(d) is a sectional view taken along the line DD of FIG. 8(a). As shown in FIGS. 8(a) to 8(d), the elastic wiring board 1 includes a connection area 24a where the connection portion 9a of the first wiring 3 and the second wiring 5 is located, and the first wiring 3 and the second wiring. 5, connection regions 24c and 24d where connection portions 9c and 9d of the first wiring 3 and functional member 6 are positioned, second wiring 5 and functional member 6; The hard-to-stretch portion 11 can be located in the connection region 24e where the connection portion 9e of the second wiring 5 and the connection portion 9f of the functional member 6 are located (not shown). The Young's modulus of the hard-to-stretch portion 11 is greater than that of the base material 2 and equal to or higher than that of the interlayer insulating layer 4 . 8(a) to (d), the difficult-to-stretch portion 11 is located over a plurality of connection regions 24a to 24e, and is also located in the entire functional member region 23 where the functional member 6 is located. . In addition, the hard-to-stretch portion 11 is located on the first surface 2a side of the base material 2 and is located on the surface of the second wiring 5 opposite to the surface facing the interlayer insulating layer 4 and the first wiring of the interlayer insulating layer 4. It is located on the surface opposite to the surface on the 3 side. In FIG. 8A, part of the first wiring and the second wiring are indicated by broken lines, and functional members are indicated by two-dot chain lines. In addition, in FIG. 8B, part of the first wiring and the second wiring is indicated by broken lines, and the hard-to-stretch portions are indicated by thick lines.

The connection region has a Young's modulus greater than that of the base material and equal to or higher than the Young's modulus of the interlayer insulating layer, that is, it is harder and less deformable than the base material and is comparable to that of the interlayer insulating layer. By providing the hard-to-stretch portion that is harder and less likely to deform, it is possible to suppress the expansion and contraction of the connection region. Thereby, it can suppress that a connection part is damaged.

The Young's modulus of the hard-to-stretch portion is greater than that of the substrate, and equal to or higher than that of the interlayer insulating layer.

The Young's modulus of the hard-to-stretch portion can be, for example, 1.1 times or more, preferably 10 times or more, that of the base material. The Young's modulus of the hard-to-stretch portion can be, for example, 5000 times or less, preferably 3000 times or less, that of the base material. By providing such a difficult-to-stretch portion in the connection region, it is possible to suppress expansion and contraction of the portion of the base material that overlaps the difficult-to-stretch portion in a plan view. Thereby, it can suppress that a connection part is damaged.

Moreover, the Young's modulus of the hard-to-stretch portion can be, for example, one or more times the Young's modulus of the interlayer insulating layer, preferably ten times or more. The Young's modulus of the hard-to-stretch portion can be, for example, 10000 times or less, preferably 250 times or less, that of the interlayer insulating layer.

Moreover, the Young's modulus of the hard-to-stretch portion can be, for example, 10 GPa or more, preferably 1 GPa or more. The Young's modulus of the hard-to-stretch portion can be, for example, 500 GPa or less, preferably 300 GPa or less. If the Young's modulus of the hard-to-stretch portion is too small, the effect of suppressing the stretching of the connection region may not be obtained. Further, if the Young's modulus of the difficult-to-stretch portion is too large, structural destruction such as cracks or cracks may occur in the difficult-to-stretch portion when the base material expands or contracts.

The method for determining the Young's modulus of the hard-to-stretch portion is the same as in the case of the interlayer insulating layer.

A metal material, for example, can be used as the material forming the hard-to-stretch portion. Examples of metal materials include copper, aluminum, stainless steel, and the like. In addition, as a material constituting the difficult-to-stretch portion, a general thermoplastic elastomer, polyimide, polyethylene naphthalate, or acrylic, urethane, epoxy, polyester, vinyl ether, polyene/thiol, or silicone You may use oligomers, polymers, etc., such as.

The thickness of the hard-to-stretch portion can be, for example, 1 μm or more and 100 μm or less.

Also, the properties of the hard-to-stretch portion may be represented by bending rigidity instead of Young's modulus. That is, the flexural rigidity of the hard-to-stretch portion may be greater than the flexural rigidity of the base material, and may be equal to or greater than the flexural rigidity of the interlayer insulating layer.
The geometrical moment of inertia of the difficult-to-stretch portion is calculated based on a cross section obtained by cutting the difficult-to-stretch portion along a plane orthogonal to the stretching direction of the stretchable wiring board.

The flexural rigidity of the difficult-to-stretch portion can be, for example, 1.1 times or more, preferably 2 times or more, and more preferably 10 times or more, that of the substrate.

The hard-to-stretch portion may have uniform deformability, or may be configured to exhibit different deformability depending on the position. For example, when the difficult-to-stretch portion has a uniform thickness, it can have uniform deformability. Further, the difficult-to-stretch portion may include a first portion and a second portion having higher deformability than the first portion. In this case, the hard-to-stretch portion exhibits different deformability depending on the position. can be configured as For example, in the example shown in FIGS. 9A and 9B, the difficult-to-stretch portion 11 includes a first portion 11a and a second portion 11b having higher deformability than the first portion 11a, and a second The portion 11b is positioned closer to the outer edge of the difficult-to-stretch portion 11 than the first portion 11a. 9(a) is a cross-sectional view showing the elastic wiring board in a stretched state, and FIG. 9(b) is a cross-sectional view showing the elastic wiring board shown in FIG. 9(a) in a relaxed state. be.

The thickness of the second portion of the hard-to-stretch portion can be made thinner than the thickness of the first portion. Also, the thickness of the second portion may at least partially decrease toward the outer edge side of the difficult-to-stretch portion. In the example shown in FIG. 9( a ), the thickness of the second portion 11 b of the difficult-to-stretch portion 11 monotonously decreases from the first portion 11 a toward the outer edge of the difficult-to-stretch portion 11 . In this case, the deformability of the base material 2 increases toward the outer edge of the hard-to-stretch part 11 in the portion of the base material 2 that overlaps the difficult-to-stretch part 11 in plan view. Therefore, it is possible to suppress a sudden change in the deformability of the base material 2 at or near the outer edge of the hard-to-stretch portion 11 . For this reason, when the stretchable wiring board 1 is relaxed, as shown in FIG. Deformation suitable for the accordion-shaped portions appearing in the first wiring 3 and the second wiring 5 can be generated. Accordingly, it is possible to prevent the first wiring and/or the second wiring from being damaged at or near the outer edge of the hard-to-stretch portion.

The hard-to-stretch portion 11 may have a hemispherical shape in cross section, as shown in FIGS. 8(c), 8(d), and 10(a), for example. In this case, the second portion 11b of the hard-to-stretch portion 11 located closer to the outer edge of the hard-to-stretch portion 11 than the first portion 11a has a thickness that decreases toward the outer edge of the hard-to-stretch portion 11 . Therefore, in the portion of the base material 2 that overlaps the hard-to-stretch portion 11 in plan view, the deformability of the base material 2 increases toward the outer edge of the hard-to-stretch portion 11 . Therefore, it is possible to suppress a sudden change in the deformability of the base material 2 at or near the outer edge of the hard-to-stretch portion 11 . Thereby, it is possible to suppress the first wiring and/or the second wiring from being damaged at or near the outer edge of the hard-to-stretch portion.

In the difficult-to-stretch portion, the density distribution of the second portion 11b of the difficult-to-stretch portion 11 may be smaller than the density distribution of the first portion 11a of the difficult-to-stretch portion 11, as shown in FIG. 10(b), for example. . The second portion 11b includes a plurality of members arranged with gaps therebetween, as shown in FIG. 10(b). The density distribution of the second portion 11b may decrease toward the outer edge side of the difficult-to-stretch portion 11 . For example, the width of the plurality of members forming the second member may decrease toward the outer edge of the difficult-to-stretch portion, and the gaps between the plural members forming the second member may be the width of the difficult-to-stretch portion. It may be larger toward the outer edge side. Each member of the second portion is made of, for example, the same material as that of the first portion.
In this case, the deformability of the base material 2 increases toward the outer edge of the hard-to-stretch part 11 in the portion of the base material 2 that overlaps the difficult-to-stretch part 11 in plan view. Therefore, it is possible to suppress a sudden change in the deformability of the base material 2 at or near the outer edge of the hard-to-stretch portion 11 . Thereby, it is possible to suppress the first wiring and/or the second wiring from being damaged at or near the outer edge of the hard-to-stretch portion.
Note that the first portion of the difficult-to-stretch portion may also include a plurality of members arranged with a gap therebetween.

Further, when the stretchable wiring board of the present disclosure has a support base material between the base material and the first wiring, for example, as shown in FIG. It may be configured as a gap between the base material 7 and the base material 2 . In this case, the first portion 11 a of the hard-to-stretch portion 11 can be configured by an adhesive layer that bonds the supporting substrate 7 and the substrate 2 together. Since there is no member in the second portion 11b of the difficult-to-stretch portion 11, the deformability of the second portion 11b is higher than that of the first portion 11a. Therefore, in the portion of the base material 2 that overlaps the hard-to-stretch portion 11 in plan view, the deformability of the base material 2 increases toward the outer edge of the hard-to-stretch portion 11 . Therefore, it is possible to suppress a sudden change in the deformability of the base material 2 at or near the outer edge of the hard-to-stretch portion 11 . Thereby, it is possible to suppress the first wiring and/or the second wiring from being damaged at or near the outer edge of the hard-to-stretch portion.

In the difficult-to-stretch portion, the Young's modulus of the second portion of the difficult-to-stretch portion may be smaller than the Young's modulus of the first portion of the difficult-to-stretch portion. In this case, the deformability of the substrate increases toward the outer edge of the difficult-to-stretch portion in the portion of the substrate that overlaps the hard-to-stretch portion in plan view. Therefore, it is possible to suppress a sudden change in the deformability of the substrate at or near the outer edge of the hard-to-stretch portion. Thereby, it is possible to suppress the first wiring and/or the second wiring from being damaged at or near the outer edge of the hard-to-stretch portion.

In addition, when the stretchable wiring board of the present disclosure has a supporting base material between the base material and the first wiring, and the hard-to-stretch part is located between the supporting base material and the base material, the hard-to-stretch The hard-to-stretch portion may be configured such that the Young's modulus of the second portion of the portion is smaller than the Young's modulus of the first portion. In this case, the difficult-to-stretch portion can be configured by an adhesive layer that bonds the supporting substrate and the substrate.

The hard-to-stretch portion 11 may lean against the functional member 6 as shown in FIG. 10(d). In this case, when the ridges of the bellows-shaped portion provided with the difficult-to-stretch portion 11 are further displaced toward the connection region 24, the difficult-to-stretch portion 11 leaning against the functional member 6 is compressed, and a repulsive force is generated. . Therefore, it is possible to suppress an increase in the height of the ridges of the bellows-shaped portion provided with the difficult-to-stretch portion. Thereby, it can suppress that a connection part is damaged. In addition, as shown in FIG. 10(d), the difficult-to-stretch portion 11 may indirectly lean on the functional member 6 via other difficult-to-stretch portions. You may lean against the functional member.

The hard-to-stretch portion may be located on the first surface side of the substrate, may be located on the second surface side of the substrate, or may be located inside the substrate.

When the difficult-to-stretch portion is located on the first surface side of the base material, the difficult-to-stretch portion 11 is, for example, shown in FIGS. , as shown in FIGS. 10A, 10B, and 10D, the second wiring 5 may be positioned on the surface opposite to the surface facing the interlayer insulating layer 4, and FIG. may be positioned between the substrate 2 and the first wiring 3 as shown in FIG. When the hard-to-stretch part is positioned between the base material and the first wiring, the hard-to-stretch part may be positioned on the first surface of the base material, and may be provided on the first surface of the base material. It may be located in a recess. Further, when the stretchable wiring board of the present disclosure has a supporting base material between the base material and the first wiring, the difficult-to-stretch part is located on the surface of the second wiring opposite to the surface facing the interlayer insulating layer. It may be located between the supporting substrate and the first wiring, or may be located between the substrate and the supporting substrate.

When the difficult-to-stretch part is located inside the base material, the difficult-to-stretch part 11 is embedded inside the base material 2, as shown in FIG. 11(b), for example. Such a base material and a hard-to-stretch part are, for example, when the base material is produced by a so-called cast molding method in which an elastomer is injected into a mold and molded, the hard-to-stretch part is put into the mold at an appropriate timing. obtained by

When the hard-to-stretch part is positioned on the second surface side of the base material, the hard-to-stretch part 11 can be positioned on the second surface 2b of the base material 2, as shown in FIG. 11(c), for example. .

The difficult-to-stretch portion may be located at least in the connection region where the connection portion of the first wiring or the second wiring is located. For example, as shown in FIGS. 7A and 7B , the difficult-to-stretch portion 11 may be positioned over the connection region 24 and the region around the connection region 24 . Further, as shown in FIGS. 8(a) to 8(d), the difficult-to-stretch portion 11 may be positioned over connection regions 24a to 24e where the plurality of connection portions 9a to 9f are respectively positioned. Further, when the connection region is a region where the connection portion between the first wiring and/or the second wiring and the functional member is located, for example, as shown in FIGS. may be located over the connection region 24 and the entire functional member region 23 . In this case, for example, as shown in FIGS. 12(a) and 12(b), the hard-to-stretch portion 11 has a frame-like shape extending along the outer edge of the functional member region 23 in plan view. good too.
Note that FIG. 12(b) is a sectional view taken along line CC of FIG. 12(a).

Above all, it is preferable that the difficult-to-stretch portion is located over the connection region and the region surrounding the connection region. That is, the area of the region where the difficult-to-stretch portion is located is preferably larger than the area of the connection region. This is because damage to the connecting portion can be effectively suppressed.

Further, as shown in FIGS. 8A to 8D, for example, when a plurality of connection regions are close to each other, it is preferable that the hard-to-stretch portion is located over the plurality of connection regions. This is because the difficult-to-stretch portion can be easily formed.

In addition, the hard-to-stretch portion includes a first connection region where the connection portion between the first wiring and the second wiring is located, and a second connection region where the connection portion between the first wiring or the second wiring and the functional member is located. It is preferably located across the By providing the connecting portion of the first wiring and the second wiring in the vicinity of the electronic component which is the functional member, the difficult-to-stretch portion can be arranged over the first connecting region and the second connecting region. In the examples shown in FIGS. 8A to 8D , the difficult-to-stretch portion 11 includes a first connection region where the connection portions 9a and 9b between the first wiring 3 and the second wiring 5 are located, and the first wiring 3 Alternatively, it is located over the second connection region where the connection portions 9c to 9f between the second wiring 5 and the functional member 6 are located.

In this case, the shortest distance between the end of the functional member region and the end of the connecting portion of the first wiring and the second wiring can be, for example, 5 μm or more and 5 mm or less, or 100 μm or more and 1 mm or less. is preferably If the shortest distance is within the above range, the hard-to-stretch portion can be easily arranged over the first connection region and the second connection region.

Moreover, the hard-to-stretch portion may have different shapes depending on the position in a plan view. For example, as shown in FIGS. 13A and 13B, the hard-to-stretch portion 11 located in the functional member region 23 has a rectangular shape in plan view, and is located in the region surrounding the functional member region 23. The hard-to-stretch portion 11 may have a circular shape.

The connection area is an area where the connection portion of the first wiring or the second wiring is located. The connection region includes a region where a connection portion between the first wiring and another member is located and a region where a connection portion between the second wiring and another member is located. Examples of the connection area include an area where the connection portion between the first wiring and the second wiring is located, an area where the connection portion between the first wiring and the functional member is located, and a connection portion between the second wiring and the functional member. is located.

When the hard-to-stretch part is also located in the area around the connection area, the dimensions of the area where the hard-to-stretch part is provided in the area around the connection area should be adjusted so that the stress concentrates on the outer edge of the connection area. can be determined so as to suppress

Of the areas around the connection area, the area where the difficult-to-stretch portion is provided may be defined as an area within a certain distance from the end of the connection area. The region can be, for example, a region within 5 mm from the end of the connection region, and may be a region within 2 mm.

Further, the difficult-to-stretch portion may be located in an intersection region where the first wiring and the second wiring intersect. To prevent the first wiring and the second wiring from being damaged or the insulation failure to occur between the first wiring and the second wiring in the intersection region by positioning the hard-to-stretch portion in the intersection region. can be done.

A method for forming the hard-to-stretch portion is appropriately selected according to the material and the like. For example, there is a method of forming a metal film on a base material or a supporting base material by a vapor deposition method, a sputtering method, or the like, and then patterning the metal film by a photolithography method. Further, a method of forming a resin film such as an organic layer on the entire surface of the base material or the supporting base material by a coating method such as a spin coating method and then patterning the resin film by a photolithography method can be used. Further, for example, there is a method of printing the material of the hard-to-stretch portion in a pattern on the base material or the supporting base material by a general printing method. In addition, a method of embedding a difficult-to-stretch part in a base material, specifically, as described above, when producing a base material by cast molding, the difficult-to-stretch part is put into the mold at an appropriate timing. method. Another example is a method of laminating a hard-to-stretch portion onto a base material or a supporting base material via an adhesive layer. The adhesive layer is not particularly limited, and general adhesives and adhesives used for wiring substrates can be used. Among these methods, the printing method is preferably used because of its high material efficiency and low manufacturing cost.

5. Functional Member The stretchable wiring board of the present disclosure is a functional member located on the first surface side of the base material, adjacent to the first wiring region and/or the second wiring region, and on which the functional member is mounted. It can have a functional member located in the region.

The functional member is appropriately selected according to the application of the elastic wiring board, and may be an active element or a passive element. Examples of active elements include transistors, ICs, LSIs (Large-Scale Integration), MEMS (Micro Electro Mechanical Systems), relays, light-emitting elements such as LEDs and OLEDs, and sensors. Examples of passive elements include resistors, capacitors, inductors, piezoelectric elements, and batteries.

Among them, a sensor is preferably used. Examples of sensors include temperature sensors, pressure sensors, optical sensors, photoelectric sensors, proximity sensors, shear force sensors, and magnetic sensors. In particular, the sensor is preferably a biosensor capable of measuring biometric information such as heartbeat, pulse, electrocardiogram, blood pressure, body temperature, blood oxygen concentration, myoelectricity, and electroencephalogram.

The functional member is connected to the first wiring and/or the second wiring. A general structure can be applied to the connection structure between the functional member and the first wiring and/or the second wiring.

The functional member may have a bellows-shaped portion if it can withstand expansion and contraction. For example, if the functional member is a TFT, OLED, or the like, it can have a bellows-shaped portion.

6. Support Base Material The stretchable wiring board of the present disclosure may have a support base material between the base material and the first wiring. The support base material is a member that supports the first wiring, the interlayer insulating layer, the second wiring and the functional member. For example, FIG. 1(b) and FIG. 2(b) are examples in which the elastic wiring board 1 has a supporting base material 7 between the base material 2 and the first wiring 3. FIG.

When the supporting base material is positioned between the base material and the first wiring, in the method for manufacturing a stretchable wiring board of the present disclosure, the tensile stress is removed from the base material bonded to the supporting base material to remove the base material. When shrinks, a bellows-shaped portion is formed in the supporting substrate, the first wiring, the interlayer insulating layer and the second wiring. The properties and dimensions of the supporting substrate are set so as to facilitate the formation of such a bellows-shaped portion.

The supporting substrate, for example, has a Young's modulus greater than that of the substrate. The Young's modulus of the supporting substrate can be, for example, 100 MPa or higher, preferably 1 GPa or higher. The Young's modulus of the supporting substrate can be, for example, 100 times or more and 50000 times or less, preferably 1000 times or more and 10000 times or less, that of the substrate. By setting the Young's modulus of the supporting base material in this way, it is possible to prevent the period of the accordion-shaped portion from becoming too small. Moreover, it is possible to suppress the occurrence of local bending in the bellows-shaped portion. On the other hand, if the Young's modulus of the supporting base material is too high, it becomes difficult to restore the base material when relaxed, and the base material is likely to crack or break. In addition, as will be described later, when the elastic wiring board of the present disclosure has a plurality of expansion/contraction control portions located in the wiring area and arranged along the first direction in which peaks and valleys of the bellows-shaped portion repeatedly appear, If the Young's modulus of the supporting base material is too small, the supporting base material is likely to deform during the step of forming the expansion/contraction control part, resulting in difficulty in positioning the expansion/contraction control part with respect to the first wiring, the second wiring, and the functional member. becomes difficult.
Also, the Young's modulus of the supporting substrate may be 100 times or less the Young's modulus of the substrate.
The method for obtaining the Young's modulus of the support substrate is the same as the method for obtaining the Young's modulus of the interlayer insulating layer.

The support base usually has a bellows-shaped portion. The bellows-shaped portion may be the same as the bellows-shaped portions of the first wiring and the second wiring.

As the support base material, any material can be used as long as it can withstand expansion and contraction, and examples thereof include a resin base material. Specific examples of materials constituting the resin substrate include polyesters such as polyethylene naphthalate and polyethylene terephthalate, polyimides, polyamides, polycarbonates, polyolefins, cycloolefin polymers, and acrylic resins. Among them, polyethylene naphthalate or polyimide is preferably used because of its good durability and heat resistance.

The thickness of the support substrate may be any thickness that can be stretched by having the bellows-shaped portion, and can be, for example, 500 nm or more, preferably 1 μm or more, and preferably 10 μm or less. is 5 μm or less. If the thickness of the supporting base material is too thin, it becomes difficult to handle the supporting base material in the manufacturing process of the supporting base material and the process of forming members on the supporting base material. Also, if the thickness of the supporting base material is too thick, it becomes difficult to restore the base material when relaxed, and the target expansion and contraction of the base material may not be obtained.

An adhesive layer may be arranged between the supporting substrate and the substrate.
The adhesive layer is not particularly limited, and general adhesives and adhesives used for wiring substrates can be used.

The adhesive layer can have a bellows shape. The bellows-shaped portion may be the same as the bellows-shaped portions of the first wiring and the second wiring.

The thickness of the adhesive layer may be any thickness as long as it is stretchable and allows the supporting substrate to be attached to the first surface side of the substrate. is in the range of 10 μm or more and 100 μm or less.

Alternatively, the adhesive layer may be a molecular adhesive layer. The term "molecular adhesion" refers to the application of a molecular adhesive compound between two adherends to bond the two adherends by chemical bonding. In the present disclosure, the substrate and supporting substrate can be adhesively bonded by chemical bonding with a molecular adhesive.

A known molecular adhesive can be used as the molecular adhesive used in the molecular adhesive layer, and the molecular adhesive is appropriately selected according to the application of the stretchable wiring board. Examples include silane coupling agents and thiol compounds.

The thickness of the molecular adhesion layer is, for example, about several nanometers.
Examples of the method of arranging the molecular adhesive layer include a method of surface-modifying the first surface of the substrate and the surface of the supporting substrate opposite to the first wiring side surface with a molecular adhesive.

7. Adjustment Layer The stretchable wiring board of the present disclosure is positioned on the surface of the second wiring opposite to the surface facing the interlayer insulating layer, or between the substrate and the first wiring, and the first wiring is located on the first wiring. The adjustment layer may be located in the second wiring region where the first wiring region and the second wiring are located, have a bellows-shaped portion, and have a Young's modulus smaller than that of the first wiring and the second wiring.

14(a) and (b) are a schematic plan view and a cross-sectional view showing another example of the stretchable wiring board of the present disclosure, and FIG. 14(b) is a cross-sectional view taken along line AA of FIG. 14(a). It is a diagram. As shown in FIGS. 14A and 14B, the elastic wiring board 1 has the first wiring 3 and the second wiring 5 on the surface opposite to the surface of the second wiring 5 facing the interlayer insulating layer 4 . The tuning layer 12 can have a Young's modulus less than . 14A and 14B, the adjustment layer 12 is located on the entire surface of the substrate 2 on the side of the first surface 2a. Note that the adjustment layer 12 may be positioned at least in the first wiring region 21 and the second wiring region 22 .

In the example shown in FIGS. 14A and 14B, the adjustment layer 12 is positioned on the surface of the second wiring 5 opposite to the surface facing the interlayer insulating layer 4, but this is not the only option. Although not shown, it may be positioned between the base material 2 and the first wiring 3 .

Between the surface of the second wiring on the side opposite to the interlayer insulating layer side, or between the substrate and the first wiring, in the first wiring region and the second wiring region, more than the first wiring and the second wiring The presence of the adjustment layer, which has a small Young's modulus, ie is softer and more deformable than the first and second wirings, allows the stress to be distributed. Therefore, even if the degree of bending or bending that occurs in the first wiring and the second wiring is locally increased, stress concentration can be reduced at locations where the degree of bending or bending is locally large. . As a result, it is possible to prevent the first wiring and the second wiring from being damaged and the resistance values of the first wiring and the second wiring from increasing when the stretchable wiring board is repeatedly stretched and contracted.

The Young's modulus of the adjustment layer is smaller than the Young's moduli of the first wiring and the second wiring. Moreover, the Young's modulus of the adjustment layer is preferably higher than that of the stretchable substrate. That is, the adjustment layer preferably has a Young's modulus intermediate between that of the first wiring and second wiring and that of the substrate. In the first wiring region and the second wiring region on the surface opposite to the surface of the second wiring on the interlayer insulating layer side or between the base material and the first wiring, the first wiring and the second wiring and the base are formed. The adjustment layer has a Young's modulus intermediate to that of the material, that is, it is softer and more deformable than the first wiring and the second wiring, and harder and less deformable than the base material, thereby reducing stress concentration. Because you can.

Moreover, the Young's modulus of the adjustment layer may be smaller than that of the supporting substrate, may be the same as that of the supporting substrate, or may be larger than that of the supporting substrate. Among others, the Young's modulus of the adjustment layer is preferably smaller than that of the supporting substrate. The first wiring, the second wiring, and the support are provided in the first wiring region and the second wiring region between the surface of the second wiring opposite to the interlayer insulating layer side, or between the base material and the first wiring. This is because stress concentration can be reduced by locating the adjustment layer which has a Young's modulus smaller than that of the substrate, that is, is softer and more deformable than the first wiring, the second wiring, and the supporting substrate.

Specifically, the Young's modulus of the adjustment layer can be less than 1 times the Young's modulus of the first wiring and the second wiring, preferably 1/10 or less, more preferably 1/20 or less. . The Young's modulus of the adjustment layer can be 1/1000 or more, preferably 1/100 or more, of the Young's moduli of the first wiring and the second wiring.
In addition, the Young's modulus of the adjustment layer can be more than 1 times, preferably 1.1 times or more, more preferably 2 times or more that of the stretchable substrate. The Young's modulus of the adjustment layer can be 100 times or less, preferably 10 times or less, that of the stretchable substrate.
This is because if the Young's modulus of the adjustment layer is too small or too large, it may become difficult to reduce the stress concentration.

Also, the Young's modulus of the adjustment layer can be, for example, 1 GPa or less, preferably 100 MPa or less, and more preferably 10 MPa or less. Also, the Young's modulus of the adjustment layer can be, for example, 10 kPa or more, preferably 1 MPa or more. This is because if the Young's modulus of the adjustment layer is too small or too large, it may become difficult to reduce the stress concentration.

The method for determining the Young's modulus of the adjustment layer is the same as the method for determining the Young's modulus of the interlayer insulating layer.

The adjustment layer has a bellows-shaped portion. The bellows-shaped portion of the adjustment layer can be the same as the bellows-shaped portion of at least one of the first wiring and the second wiring.

The material of the adjustment layer may have the above-described Young's modulus, and may or may not have elasticity. Above all, it is preferable that the material of the adjustment layer has stretchability. This is because if the adjustment layer contains a stretchable material, it can have resistance to deformation.

Examples of non-stretchable materials used for the adjustment layer include resins. As the resin, a general resin can be used, and for example, any of thermoplastic resin, thermosetting resin, photo-setting resin and the like can be used. Moreover, when the adjustment layer contains a resin, a resin base material can also be used as the adjustment layer.

The stretchability of the stretchable material used for the adjustment layer can be the same as the stretchability of the stretchable base material described later.
Examples of stretchable materials used for the adjustment layer include elastomers. As the elastomer, general thermoplastic elastomers and thermosetting elastomers can be used. Specifically, styrene-based elastomers, olefin-based elastomers, urethane-based elastomers, amide-based elastomers, silicone rubbers, urethane rubbers, and fluororubbers can be used. , polybutadiene, polyisobutylene, polystyrene butadiene, polychloroprene, and the like.

Moreover, it is preferable that the adjustment layer has insulating properties when it is in contact with at least one of the first wiring and the second wiring. A resin or elastomer can be used as an adjustment layer having insulating properties.

The adjustment layer may be positioned at least in the first wiring region and the second wiring region. may be located

Above all, it is preferable that the adjustment layer is positioned continuously with the first wiring region, the second wiring, and the functional member region adjacent to the first wiring region and/or the second wiring region. For example, in FIG. 14( b ), the adjustment layer 12 is positioned continuously with the first wiring region 21 , the second wiring 22 , and the functional member region 22 adjacent to the second wiring region 22 .
Here, in the elastic wiring board, the height of the ridges of the bellows-shaped portion is locally large due to variations in the thickness of the base material, differences in the distribution density of the wiring provided on the base material, and the like. can be. For example, the wiring may have a large ridge in the vicinity of the boundary between the wiring and the functional member. In this case, a large stress is applied to the connecting portion between the wiring and the functional member, which may break the connecting portion.
On the other hand, since the adjustment layer is positioned continuously with the first wiring region and/or the second wiring region and the functional member region, the first wiring and/or the second wiring and the functional member In the vicinity of the boundary between the first wiring and/or the second wiring, it is possible to suppress the occurrence of large ridges. Thereby, it is possible to suppress breakage of the connecting portion between the first wiring and/or the second wiring and the functional member.

When the adjustment layer is positioned continuously with the first wiring region and/or the second wiring region and the functional member region, the adjustment layer functions at least with the first wiring region and/or the second wiring region. For example, it may be positioned all over the functional member region, or may be positioned partially in the functional member region. When the adjustment layer is partially located in the functional member region, for example, the adjustment layer may have a shape having an opening that partially exposes the functional member in plan view. .

Also, the adjustment layer may not be positioned in the functional member region, that is, may not be positioned continuously between the first wiring region and/or the second wiring region and the functional member region. In this case, as will be described later, the stretchable wiring board of the present disclosure is positioned on the first surface side of the base material, the second surface side of the base material, or inside the base material, and the functional member region It is preferable to have a second expansion/contraction control portion located in the functional member peripheral region located around the perimeter of the functional member and extending to the boundary between the functional member peripheral region and the functional member region. A second expansion/contraction control section is provided in the functional member peripheral region, and the second expansion/contraction control section extends to the boundary between the functional member peripheral region and the functional member region, This is because it is possible to suppress the occurrence of large ridges in the wiring in the vicinity of the functional member. Thereby, it is possible to suppress damage to the connecting portion between the first wiring or the second wiring and the functional member.

Further, the adjustment layer may be positioned on the surface of the second wiring opposite to the surface facing the interlayer insulating layer, or may be positioned between the base material and the first wiring.
When the adjustment layer is positioned between the substrate and the first wiring, and when the support substrate is positioned between the substrate and the first wiring, the adjustment layer is positioned between the support substrate and the first wiring. It may be located between the wires, or it may be located between the substrate and the supporting substrate.

The conditioning layer is generally non-tacky. This is because post-processing becomes difficult if the adjustment layer has adhesiveness. In addition, as described later, the stretchable wiring board of the present disclosure may have an adhesive layer for attachment to an object, but the adjustment layer is distinguished from such an adhesive layer.
Here, "not having adhesiveness" means that the adhesive strength of the adjustment layer is 0.01 N/25 mm or less, preferably 0.005 N/25 mm or less, and more preferably 0.001 N/25 mm or less. .

As a method for measuring the adhesive strength of the adjustment layer, a method of conducting a 180° peel test using a sample of the adjustment layer can be adopted. Examples of the method of preparing a sample of the adjustment layer include a method of taking out a part of the adjustment layer from the elastic wiring board as a sample, and a method of taking out a part of the adjustment layer as a sample before forming the elastic wiring board. . In addition, as a method for measuring the adhesive strength of the adjustment layer, a method of analyzing the materials forming the adjustment layer and determining the adhesive strength of the adjustment layer based on an existing database of materials can also be adopted. In the 180° peeling test, first, a test piece with a width of 25 mm is obtained, and a glass plate with a width of 25 mm is attached to the adjustment layer side of the test piece. Next, using a tensile tester, the adhesive strength (N/25 mm) to the glass plate is measured under the conditions of tensile speed: 1200 mm/min, peel angle: 180°, temperature: 20°C, humidity: 50%.

The thickness of the adjustment layer may be any thickness that can withstand expansion and contraction, and is appropriately selected according to the material of the adjustment layer. The thickness of the adjustment layer can be, for example, 0.1 μm or more, preferably 1 μm or more, and more preferably 10 μm or more. Also, the thickness of the adjustment layer can be, for example, 1 mm or less, preferably 500 μm or less, and more preferably 100 μm or less. If the adjustment layer is too thin, the effect of reducing stress concentration may not be sufficiently obtained. Moreover, if the adjustment layer is too thick, even if the Young's modulus satisfies the above relationship, the bending rigidity of the adjustment layer increases, and it may become difficult to reduce the stress concentration. The bending rigidity is represented by the product of the area moment of inertia of the target member and the Young's modulus of the material of the target member.

The method of arranging the adjustment layer on the side opposite to the side of the supporting substrate of the wiring or between the supporting substrate and the wiring depends on the material of the adjustment layer, the layer structure of the elastic wiring substrate, and the like. Selected as appropriate. Examples include a method of applying a resin composition for the adjustment layer, a method of laminating the adjustment layer via an adhesive layer, a method of heat laminating the base material and the adjustment layer, and a method of simultaneously molding the base material and the adjustment layer. be done.

The adhesive layer is not particularly limited, and general adhesives and adhesives used for wiring substrates can be used.

The adhesive layer usually has a bellows-shaped portion. The bellows-shaped portion of the adhesive layer can be the same as the bellows-shaped portion of at least one of the first wiring and the second wiring.

The thickness of the adhesive layer may be any thickness that allows expansion and contraction and allows bonding of the adjustment layer via the adhesive layer.

8. First Stretch Control Unit The stretchable wiring board of the present disclosure is positioned on the first surface side of the base material, the second surface side of the base material, or inside the base material, and has the first wiring region and/or the first wiring region. It is possible to have a plurality of expansion/contraction control portions located in the two wiring regions and arranged along the first direction in which peaks and valleys of the bellows-shaped portion appear repeatedly. In addition, hereinafter, this expansion/contraction control unit may be referred to as a first expansion/contraction control unit.
The first expansion/contraction control part is a member provided to control the expansion/contraction of the base material.

15(a) and (b) are a schematic plan view and a cross-sectional view showing another example of the stretchable wiring board of the present disclosure, and FIG. 15(b) is a cross-sectional view taken along line EE of FIG. 15(a). is. As shown in FIGS. 15(a) and 15(b), the elastic wiring board 1 is positioned in the second wiring region 22, and arranged along the first direction D1 in which the peaks and valleys of the accordion-shaped portion appear repeatedly. A plurality of first expansion/contraction control units 41 can be provided. In FIGS. 15A and 15B, the first expansion/contraction control part 41 is located on the first surface 2a side of the base material 2 and is opposite to the surface of the second wiring 5 on the interlayer insulating layer 4 side. side surface and the surface of the interlayer insulating layer 4 on the side of the second wiring 5 . In addition, in FIG. 15A, the first wiring is indicated by a broken line.

By providing the first expansion/contraction control section in the first wiring area and/or the second wiring area, the period, amplitude, etc. of the bellows-shaped portion can be controlled. Therefore, it is possible to prevent the first wiring and/or the second wiring from being greatly curved or bent locally. As a result, damage to the first wiring and the second wiring can be suppressed.

FIG. 16 is an enlarged view of the wiring area in FIG. 15(b). As shown in FIG. 16 , in the second wiring region, a plurality of first stretches along the first direction D1 in which the peaks 31 and the valleys 32 repeatedly appear in the in-plane direction of the first surface 2a of the base material 2 The control units 41 are arranged with a cycle of F2. As a result, the base material 2 has a portion that easily expands and contracts and a portion that does not easily expand and contract repeatedly at a period F2 along the direction in which the second wiring 5 extends. In this case, when the base material 2 is relaxed, a bellows-shaped portion having a period F1 corresponding to the period F2 of the first expansion/contraction control portion 41 is likely to occur in the second wiring 5 . That is, the period F1 of the bellows-shaped portion can be controlled by the first expansion/contraction control section 41 .

Advantages of controlling the period of the bellows portion will be described below. By arranging a plurality of first expansion/contraction control units with a period F2 along the first direction in which the accordion-shaped portions appear, the period F1 of the accordion-shaped portions appearing in the first wiring and/or the second wiring can be controlled. . As a result, it is possible to prevent the period F1 of the bellows-shaped portion from being disturbed and the height of the ridges of the bellows-shaped portion to be locally increased. As a result, it is possible to prevent the first wiring and the second wiring from being damaged due to the application of a large stress to the first wiring and the second wiring.

Note that the period of the accordion-shaped portion is the average value of the intervals between the peak portions of the accordion-shaped portion in the first direction. Also, the period of the first expansion/contraction control units is the average value of the intervals of the plurality of first expansion/contraction control units in the first direction. Hereinafter, the period of the bellows-shaped portion may be referred to as the first period, and the period of the first expansion/contraction control portion may be referred to as the second period.

When the first cycle control of the bellows-shaped portion by the first expansion/contraction control section is appropriately realized, the first expansion/contraction control portions are arranged in a second cycle corresponding to the first cycle of the bellows-shaped portion. Become. In the example shown in FIG. 14, the second period F2 of the first expansion/contraction control section 41 is the same as the first period F1 of the accordion-shaped portion. In this case, the first expansion/contraction control portion 41 is positioned at a specific phase portion of the accordion-shaped portion, for example, at the trough portion 32 of the accordion-shaped portion.

Note that depending on the Young's modulus and thickness of the base material, the first period of the bellows-shaped portion appearing in the first wiring and/or the second wiring provided on the base material and the second period of the plurality of first expansion/contraction control portions may vary. may not match. For example, the second period of the first expansion/contraction control part may be longer than the first period of the bellows shaped part, or may be shorter than the first period of the bellows shaped part. In either case, the portion of the first wiring region and/or the second wiring region where the first expansion/contraction control portion is provided tends to be the portion of the bellows-shaped portion with a specific phase. For example, the portion of the base material provided with the first expansion/contraction control portion can be the ridges or troughs of the bellows-shaped portion. Therefore, it is possible to suppress the first period of the bellows-shaped portion from being disturbed, so that it is possible to suppress a local increase in the height of the ridges of the bellows-shaped portion.

In this way, the plurality of first expansion/contraction control units can play the role of controlling the first period of the bellows-shaped portion generated in the first wiring and/or the second wiring.
The second period of the first expansion/contraction control part can be, for example, m times or 1/n the first period of the bellows-shaped part. where m and n are positive integers. Preferably, m is 3 or less and n is 4 or less. The second period of the first expansion/contraction control section can be, for example, 5 μm or more and 10 mm or less.

The Young's modulus of the first expansion/contraction control part may be greater than the Young's modulus of the substrate, or may be less than or equal to the Young's modulus of the substrate.

When the Young's modulus of the first stretch control part is larger than the Young's modulus of the substrate, the Young's modulus of the first stretch control part can be, for example, 10 GPa or more and 500 GPa or less, preferably 1 GPa or more and 300 GPa or less. is. If the Young's modulus of the first expansion/contraction control section is too small, it may be difficult to control the expansion/contraction. Further, if the Young's modulus of the first expansion/contraction control part is too large, the first expansion/contraction control part may suffer structural destruction such as cracks or fractures when the base material expands or contracts.
In this case, the Young's modulus of the first expansion/contraction control part can be, for example, 1.1 times or more and 5000 times or less, and preferably 10 times or more and 3000 times or less, that of the base material. By providing such a first expansion/contraction control section in the base material, it is possible to suppress the expansion and contraction of the portion of the base material that overlaps with the first expansion/contraction control section in a plan view. For this reason, the base material can be divided into a portion that easily expands and contracts and a portion that does not easily expand and contract. This makes it possible to control the period, amplitude, etc. of the accordion-shaped portion appearing on the substrate.
The method for obtaining the Young's modulus of the first expansion/contraction control part is the same as in the case of the interlayer insulating layer.

When the Young's modulus of the first expansion/contraction control part is larger than the Young's modulus of the base material, a metal material can be used as the material constituting the first expansion/contraction control part. Examples of metal materials include copper, aluminum, stainless steel, and the like. In addition, as a material constituting the first expansion/contraction control part, general thermoplastic elastomers, oligomers and polymers such as acrylic, urethane, epoxy, polyester, vinyl ether, polyene/thiol or silicone may be used. may be used.
The thickness of the first expansion/contraction control part can be, for example, 1 μm or more and 100 μm or less.

Further, when the Young's modulus of the first expansion control part is equal to or less than the Young's modulus of the base material, the Young's modulus of the first expansion control part can be, for example, 10 MPa or less, and may be 1 MPa or less. In addition, the Young's modulus of the first expansion/contraction control part can be, for example, 1 or less times the Young's modulus of the substrate, and may be 0.8 times or less. In this case, compared to the case where the Young's modulus of the first expansion/contraction control part is larger than the Young's modulus of the base material, the amplitude of the bellows-shaped part appearing in the base material increases, so the stretchability of the elastic wiring board also increases. . Further, even if the Young's modulus of the first expansion/contraction control part is equal to or lower than the Young's modulus of the base material, the portion of the base material that overlaps the first expansion/contraction control part in plan view and the first expansion/contraction control part A difference in stretchability occurs between portions that do not visually overlap. That is, the base material can be divided into a portion that easily expands and contracts and a portion that does not easily expand and contract. This makes it possible to control the period, amplitude, etc. of the accordion-shaped portion appearing on the substrate.

When the Young's modulus of the first expansion control part is equal to or lower than the Young's modulus of the base material, general thermoplastic elastomers and thermosetting elastomers can be used as the material constituting the first expansion control part. Examples include styrene elastomers, acrylic elastomers, olefin elastomers, urethane elastomers, silicone rubbers, urethane rubbers, fluororubbers, nitrile rubbers, polybutadiene, and polychloroprene.
The thickness of the first expansion/contraction control part can be, for example, 1 μm or more and 100 μm or less.

Also, the characteristic of the first expansion/contraction control section may be represented by bending rigidity instead of Young's modulus. That is, the flexural rigidity of the first expansion/contraction control part may be greater than the flexural rigidity of the substrate, or may be less than or equal to the flexural rigidity of the substrate.
The geometrical moment of inertia of the first expansion/contraction control part is calculated based on the cross section of the first expansion/contraction control part cut by a plane orthogonal to the expansion/contraction direction of the elastic wiring board.

When the bending rigidity of the first expansion/contraction control part is greater than the bending rigidity of the base material, the bending rigidity of the first expansion/contraction control part can be, for example, 1.1 times or more the bending rigidity of the base material, which is preferable. is 2 times or more, more preferably 10 times or more.
Further, when the bending rigidity of the first expansion/contraction control part is equal to or less than the bending rigidity of the base material, the bending rigidity of the first expansion/contraction control part can be set to, for example, one time or less of the bending rigidity of the base material. 0.8 times or less.

The first expansion/contraction control part may have uniform deformability, or may be configured to exhibit different deformability depending on the position. For example, when the first expansion/contraction control part has a uniform thickness, it can have uniform deformability. Also, the first expansion/contraction control section may include a first portion and a second portion having higher deformability than the first portion. can be configured to exhibit different deformability depending on the

In the first expansion/contraction control section 41, for example, as shown in FIGS. 17(a) and 17(b), the first portion 41a constitutes the central portion of the first expansion/contraction control section 41 in the first direction D1, The two portions 41b may constitute both ends of the first expansion/contraction control section 41 in the first direction D1. That is, the first expansion/contraction control section 41 may include a first portion 41a and a pair of second portions 41b sandwiching the first portion 41a. 17(a) is a cross-sectional view showing the elastic wiring board in a stretched state, and FIG. 17(b) is a cross-sectional view showing the elastic wiring board shown in FIG. 17(a) in a relaxed state. be.
Although not shown, in the first expansion/contraction control section, the second portion constitutes the central portion of the first expansion/contraction control portion, and the first portion constitutes both end portions of the first expansion/contraction control portion. good too.

The thickness of the second portion of the first expansion/contraction control portion can be made thinner than the thickness of the first portion. Also, the thickness of the second portion may at least partially decrease away from the first portion. In the example shown in FIG. 17(a), the thickness of the second portion 41b monotonously decreases with increasing distance from the first portion 41a. In this case, the deformability of the second wiring region of the substrate increases toward the end of the first expansion/contraction control portion. As a result, as shown in FIG. 17(b), the central portion of the first expansion/contraction control portion 41, here the first portion 41a, tends to be a specific phase portion of the bellows-shaped portion such as a trough. In addition, the first portion is easily deformed along the shape of the peaks or valleys of the bellows-shaped portion. Therefore, the deformability and stretchability of the first wiring region and/or the second wiring region of the substrate can be maintained while ensuring the stability of the period of the bellows-shaped portion by the central portion of the first expansion/contraction control portion. can be done.

For example, as shown in FIG. 18A, the first expansion/contraction control section 41 may have a hemispherical shape in cross section. In this case, in the vicinity of the ends of the first expansion/contraction control portion, the thickness decreases toward the ends. Therefore, the above-described first portion and second portion can be configured in the first expansion/contraction control section.
Also in this case, the first portion of the first expansion/contraction control portion is likely to be the portion of the specific phase of the bellows-shaped portion. Also, the second portion of the first expansion/contraction control portion is easily deformed along the shape of the peaks or valleys of the bellows-shaped portion. Therefore, it is possible to maintain the deformability and stretchability of the first wiring region and/or the second wiring region of the substrate while ensuring the stability of the period of the accordion-shaped portion.

For example, as shown in FIG. It may be smaller than the distribution. In the example shown in FIG. 18(b), the second portion 41b includes a plurality of members spaced apart. Also, the density distribution of the second portion may decrease with distance from the first portion. For example, the widths of the plurality of members that make up the second member may decrease as they move away from the first portion, and the gaps between the plurality of members that make up the second member are spaced apart from the first portion. It may be larger as it grows. Each member of the second portion is made of, for example, the same material as that of the first portion.
Also in this case, the deformability of the first wiring region and/or the second wiring region of the substrate is higher in the second portion than in the first portion of the first expansion/contraction control portion. Therefore, the first portion tends to be a portion of the bellows-shaped portion with a specific phase. In addition, the second portion is easily deformed along the shape of the ridges or troughs of the bellows-shaped portion. Therefore, it is possible to maintain the deformability and stretchability of the first wiring region and/or the second wiring region of the substrate while ensuring the stability of the period of the accordion-shaped portion.

In addition, when the stretchable wiring board of the present disclosure has a support base material between the base material and the first wiring, the first stretch control unit may be configured to extend the first stretch as shown in FIG. 18C, for example. The second portion 41 b of the control section 41 may be configured as a gap between the support base material 7 and the base material 2 . In this case, the first portion 41a of the first expansion/contraction control portion 41 can be configured by a member that can function as an adhesive that joins the support base material 7 and the base material 2 together. Since there is no member in the second portion 41b, the deformability of the second portion 41b is higher than that of the first portion 41a. Therefore, the first portion 41a is likely to be a portion of a specific phase of the bellows-shaped portion. Moreover, the second portion 41b does not hinder the generation or deformation of the bellows-shaped portion. Therefore, it is possible to maintain the deformability and stretchability of the first wiring region and/or the second wiring region of the substrate while ensuring the stability of the period of the accordion-shaped portion.

In the first expansion/contraction control section, the Young's modulus of the second portion may be smaller than the Young's modulus of the first portion. In this case, the deformability of the first wiring region and/or the second wiring region of the substrate is higher in the second portion than in the first portion of the first expansion/contraction control portion. Therefore, the first portion tends to be a portion of the bellows-shaped portion with a specific phase. In addition, the second portion is easily deformed along the shape of the ridges or troughs of the bellows-shaped portion. Therefore, it is possible to maintain the deformability and stretchability of the first wiring region and/or the second wiring region of the substrate while ensuring the stability of the period of the accordion-shaped portion.

Further, when the stretchable wiring board of the present disclosure has a supporting base material between the base material and the first wiring, and when the first expansion/contraction control part is positioned between the supporting base material and the base material Alternatively, the first expansion/contraction control part may be configured such that the Young's modulus of the second part of the first expansion/contraction control part is smaller than the Young's modulus of the first part. In this case, the first expansion/contraction control part can be composed of a member that can function as an adhesive that joins the supporting base material and the base material.

For example, as shown in FIG. 18(d), the first expansion/contraction control units 41 are arranged such that at least two first expansion/contraction control units 41 are positioned within one period of the bellows-shaped portion and are in contact with each other. good too. In this case, when the peaks of the bellows-shaped portion try to increase in height, the first expansion/contraction control portions that are in contact with each other are compressed, and a repulsive force is generated. Therefore, it is possible to suppress an increase in the height of the ridges of the bellows-shaped portions provided with the first expansion/contraction control portions that are in contact with each other.

The first expansion/contraction control part may be positioned on the first surface side of the base material, may be positioned on the second surface side of the base material, or may be positioned inside the base material.

When the first expansion/contraction control part is located on the first surface side of the base material, the first expansion/contraction control part 41 is connected to the second wiring as shown in FIGS. 5 may be located on the surface opposite to the surface facing the interlayer insulating layer 4, and as shown in FIG. may When the first expansion/contraction control part is positioned between the base material and the first wiring, the first expansion/contraction control part may be positioned on the first surface of the base material. It may be positioned in a recess provided on one surface. Further, when the stretchable wiring board of the present disclosure has a supporting base material between the base material and the first wiring, the first expansion/contraction control part is provided on the side opposite to the interlayer insulating layer side of the second wiring. It may be positioned on the plane, may be positioned between the supporting substrate and the first wiring, or may be positioned between the substrate and the supporting substrate.

When the first expansion/contraction control section is positioned inside the base material, the first expansion/contraction control section 41 is embedded inside the base material 2, as shown in FIG. 19(b), for example. Such a base material and the first expansion/contraction control part are used, for example, when the base material is produced by a so-called cast molding method in which an elastomer is injected into a mold and molded, and the first expansion/contraction control part is placed in the mold. Obtained by throwing in at the right time.

When the first expansion/contraction control part is positioned on the second surface side of the base material, the first expansion/contraction control part 41 is configured separately from the base material 2 as shown in FIG. Alternatively, it may be configured integrally with the substrate 2 as shown in FIGS. 19(d) and (e). Further, when the first expansion/contraction control part is configured integrally with the base material, the first expansion/contraction control part 41 is, for example, a protrusion provided on the base material 2 as shown in FIG. 19(d). Alternatively, it may be a recess provided in the substrate 2 as shown in FIG. 19(e). The term "integral" means that there is no interface between the base material and the first expansion/contraction control part.
Even in the case where the first expansion/contraction control portion composed of the concave portion is provided in the base material, the wiring area of the base material is divided into a portion where expansion/contraction easily occurs and a portion where expansion/contraction does not easily occur. 2 repeats along the direction in which the wiring extends. For this reason, it is possible to prevent the period of the accordion-shaped portion from being disturbed and the height of the crest portion of the accordion-shaped portion from being locally increased. As a result, it is possible to prevent the first wiring and the second wiring from being damaged due to the application of a large stress to the first wiring and the second wiring.

The first expansion/contraction control part 41 may be provided on both the first surface 2a side and the second surface 2b side of the substrate 2, as shown in FIGS. 20(a) and 20(b), for example. In this case, as shown in FIG. 20( a ), the first portion 41 a of the first expansion/contraction control section 41 located on the first surface 2 a side of the base material 2 and the first portion 41 a located on the second surface 2 b side of the base material 2 The first expansion/contraction control section 41 may be arranged so that the first expansion/contraction control section 41 does not overlap the first portion 41a of the first expansion/contraction control section 41 in plan view. 20(a) is a cross-sectional view showing the elastic wiring board in a stretched state, and FIG. 20(b) is a cross-sectional view showing a state in which the elastic wiring board shown in FIG. 20(a) is relaxed. be. In the example shown in FIG. 20B, the first expansion/contraction control part 41 located on the side of the first surface 2a of the base material 2 corresponds to the troughs of the bellows-shaped part, and is located on the side of the second surface 2b of the base material 2. The first expansion/contraction control portion 41 located at corresponds to the crest portion of the bellows-shaped portion.

The first expansion/contraction control part may be positioned so as to overlap the first wiring and/or the second wiring when viewed in plan, or positioned so as not to overlap the first wiring and/or the second wiring when viewed in plan. good too. For example, in FIG. 15(a), the first expansion/contraction control unit 41 is positioned so as to overlap the second wiring 5 in plan view, and in FIG. 21(a), the first expansion/contraction control unit 41 It is positioned so as not to overlap with the second wiring 5 in plan view.
When the first expansion/contraction control section does not overlap the first wiring and/or the second wiring in plan view, the first expansion/contraction control section and the first wiring or the second wiring can be positioned on the same plane. Arranging a plurality of first expansion/contraction control parts along a first direction in which accordion-shaped parts appear even when the first expansion/contraction control parts do not overlap the first wiring and/or the second wiring in a plan view. Therefore, it is possible to prevent the period of the bellows-shaped portion from being disturbed and the height of the ridges of the bellows-shaped portion from being locally increased. As a result, it is possible to prevent the first wiring and the second wiring from being damaged due to the application of a large stress to the first wiring and the second wiring. In addition, when the first expansion/contraction control part and the first wiring or the second wiring are positioned on the same plane, the first expansion/contraction control part and the first wiring or the second wiring are formed simultaneously in the same process. can be done.

The shape of the first expansion/contraction control portion in plan view is not particularly limited. For example, as shown in FIG. 15A, the first expansion/contraction control section 41 may extend in a direction that intersects, for example, a direction perpendicular to the first direction D1 in which the bellows-shaped portion appears. As shown in b), the first expansion control part 41 may have a circular shape, and as shown in FIG. 21(c), the first expansion control part 41 has a honeycomb shape. may be When the first expansion/contraction control section has a circular shape, the circular shape may be a perfect circle or an ellipse.

A circular shape and a honeycomb shape are isotropic shapes compared to a rectangular shape. Therefore, when a force such as tensile stress is applied to the base material, isotropic elongation can be generated in the portion of the base material that overlaps the first expansion/contraction control section in a plan view and in the vicinity thereof.

A method for forming the first expansion/contraction control portion is appropriately selected according to the material and the like. For example, there is a method of forming a metal film on a base material or a supporting base material by a vapor deposition method, a sputtering method, or the like, and then patterning the metal film by a photolithography method. Further, a method of forming a resin film such as an organic layer on the entire surface of the base material or the supporting base material by a coating method such as a spin coating method and then patterning the resin film by a photolithography method can be used. Further, for example, there is a method of printing the material of the first expansion/contraction control part in a pattern on the base material or the support base material by a general printing method. Among these methods, the printing method is preferably used because of its high material efficiency and low manufacturing cost.

9. Second expansion/contraction control unit The elastic wiring board of the present disclosure is positioned on the first surface side of the base material, on the second surface side of the base material, or inside the base material, and is positioned around the functional member region. It can have a second expansion/contraction control portion located in the functional member peripheral region where the functional member peripheral region is located and extending to the boundary between the functional member peripheral region and the functional member region.

As shown in FIGS. 15(a) and 15(b), the elastic wiring board 1 is positioned in the functional member peripheral region 25 positioned around the functional member region 23, and is functionally connected to the functional member peripheral region 25. It can have a second stretch control 42 that extends to the boundary between it and the member region 23 . In FIGS. 15(a) and (b), the second expansion/contraction control part 42 extends beyond the boundary between the functional member peripheral region 25 and the functional member region 23 to reach the functional member region 23, thereby increasing the functionality. They are located throughout the member area 23 . In addition, the second expansion/contraction control part 42 is located on the first surface 2a side of the base material 2 and is located on the surface of the functional member 6 opposite to the surface of the interlayer insulating layer 4 side and on the interlayer insulating layer 4 side. It is located on the surface on the functional member 6 side.

A second expansion/contraction control section is provided in the functional member peripheral region, and the second expansion/contraction control section extends to the boundary between the functional member peripheral region and the functional member region, It is possible to suppress the occurrence of large ridges on the first wiring and/or the second wiring in the vicinity of the functional member. Thereby, it is possible to suppress damage to the connecting portion between the functional member and the first wiring and/or the second wiring.

The Young's modulus, flexural rigidity, material, thickness, etc. of the second expansion/contraction control section can be the same as those of the first expansion/contraction control section.

The Young's modulus of the first expansion/contraction control section and the Young's modulus of the second expansion/contraction control section may be the same. In this case, the first expansion/contraction control section and the second expansion/contraction control section can be simultaneously formed in the same process, so the process of forming the first expansion/contraction control section is simplified.
Also, the Young's modulus of the first expansion/contraction control section and the Young's modulus of the second expansion/contraction control section may be different. In this case, it is preferable that the Young's modulus of the second expansion/contraction control section is larger than the Young's modulus of the first expansion/contraction control section.

When the Young's modulus of the base material is called E1, the Young's modulus of the second expansion control part is called E21, and the Young's modulus of the first expansion control part is called E22, examples of combinations are given below.
Example 1: E1<E21=E22
Example 2: E1<E22<E21
Example 3: E22≤E1<E21
Example 4: E21=E22≤E1

The material and thickness of the first expansion/contraction control section and the material and thickness of the second expansion/contraction control section may be the same. In this case, the step of forming the first expansion/contraction control portion is simplified.
Also, the material and thickness of the first expansion/contraction control section and the material and thickness of the second expansion/contraction control section may be different. In this case, it is preferable that the thickness of the second expansion/contraction control section is thinner than the thickness of the first expansion/contraction control section. This is because the functional member is generally thicker than the first wiring and the second wiring. By making the thickness of the second expansion/contraction control part thinner than the thickness of the first expansion/contraction control part, unevenness and steps between the first wiring area and/or the second wiring area and the functional member area are reduced. be able to. As a result, it is possible to suppress the occurrence of element peeling due to catching. In addition, it is possible to reduce discomfort when a user wears an electronic device having an elastic wiring board.

The second expansion/contraction control part may have uniform deformability, or may be configured to exhibit different deformability depending on the position. For example, when the second expansion/contraction control part has a uniform thickness, it can have uniform deformability. Also, the second expansion/contraction control section may include a first portion and a second portion having higher deformability than the first portion. can be configured to exhibit different deformability depending on the For example, in the example shown in FIGS. 22A and 22B, the functional member region 23 is adjacent to the second wiring region 22, and the second expansion/contraction control section 42 includes the first portion 42a and the first and a second portion 42b having higher deformability than the portion 42a, and the second portion 42b is located closer to the second wiring region 22 than the first portion 42a. 22(a) is a cross-sectional view showing the elastic wiring board in a stretched state, and FIG. 22(b) is a cross-sectional view showing the elastic wiring board shown in FIG. 22(a) in a relaxed state. be.

The thickness of the second portion of the second expansion/contraction control portion can be made thinner than the thickness of the first portion. Also, the thickness of the second portion may at least partially decrease toward the first wiring region side and/or the second wiring region side. In the example shown in FIG. 22( a ), the functional member region 23 is adjacent to the second wiring region 22 , and the thickness of the second portion 42 b of the second expansion/contraction control section 42 increases from the side of the first portion 42 a to the second portion 42 a. It monotonically decreases toward the two-wiring region 22 side. In this case, the deformability of the functional member peripheral region 25 of the substrate 2 increases toward the second wiring region 22 . Therefore, it is possible to suppress a rapid change in deformability of the base material 2 at or near the boundary between the functional member region 23 and the second wiring region 22 . Therefore, when the stretchable wiring board 1 is relaxed, as shown in FIG. A deformation that conforms to the bellows can be produced. This can prevent the second wiring from being damaged at or near the boundary between the functional member region and the second wiring region. Further, although not shown, when the functional member region is adjacent to the first wiring region, the second expansion/contraction control unit causes the boundary between the functional member region and the first wiring region or the vicinity thereof. Damage to the first wiring can be suppressed.

For example, as shown in FIGS. 23A and 23B, the second expansion/contraction control part 42 may have a hemispherical shape covering the entire functional member 6 located in the functional member region 23. good. 23A and 23B, the functional member region 23 is adjacent to the second wiring region 22, and the second wiring region 22 side of the second expansion/contraction control portion 42 is closer to the second wiring region 22 than the first portion 42a. , the thickness of the second portion 42b decreases toward the second wiring region 22 side. Therefore, the deformability of the region around the functional member of the substrate increases toward the second wiring region. Therefore, it is possible to suppress a rapid change in deformability of the base material at or near the boundary between the functional member region and the second wiring region. This can prevent the second wiring from being damaged at or near the boundary between the functional member region and the second wiring region. Further, although not shown, when the functional member region is adjacent to the first wiring region, the second expansion/contraction control unit causes the boundary between the functional member region and the first wiring region or the vicinity thereof. Damage to the first wiring can be suppressed.

For example, as shown in FIG. It may be smaller than the distribution. The second portion 42b includes a plurality of members arranged with gaps therebetween, as shown in FIG. 23(b). FIG. 23(b) is an example where the functional member region 23 is adjacent to the second wiring region 22, and the density distribution of the second portion 42b may decrease toward the second wiring region 22. FIG. For example, the widths of the plurality of members that make up the second member may decrease toward the first wiring region and/or the second wiring region, and the gaps between the plurality of members that make up the second member may be , the first wiring area and/or the second wiring area. Each member of the second portion is made of, for example, the same material as that of the first portion.
In FIG. 23(b), the deformability of the functional member peripheral region 25 of the substrate 2 increases toward the second wiring region 22. In FIG. Therefore, it is possible to suppress a rapid change in deformability of the base material at or near the boundary between the functional member region and the second wiring region. This can prevent the second wiring from being damaged at or near the boundary between the functional member region and the second wiring region. Further, although not shown, when the functional member region is adjacent to the first wiring region, the second expansion/contraction control unit causes the boundary between the functional member region and the first wiring region or the vicinity thereof. Damage to the first wiring can be suppressed.
Note that the first portion of the second expansion/contraction control section may also include a plurality of members arranged with a gap therebetween.

In addition, when the stretchable wiring board of the present disclosure has a supporting base material between the base material and the first wiring, the second part of the second expansion/contraction control part is the gap between the supporting base material and the base material. It may be configured as a part. In this case, the first portion of the second expansion/contraction control portion is composed of a member that can function as an adhesive that joins the supporting base material and the base material. Since there is no member in the second portion, the deformability of the second portion is higher than the deformability of the first portion. Therefore, the deformability of the region around the functional member of the substrate increases toward the first wiring region and/or the second wiring region. Therefore, it is possible to suppress a rapid change in deformability of the base material at or near the boundary between the functional member region and the first wiring region and/or the second wiring region. This can prevent the first wiring and/or the second wiring from being damaged at or near the boundary between the functional member region and the first wiring region and/or the second wiring region.

In the second expansion/contraction control section, the Young's modulus of the second portion of the second expansion/contraction control section may be smaller than the Young's modulus of the first section of the second expansion/contraction control section. In this case, the deformability of the functional member peripheral region of the substrate increases toward the first wiring region and/or the second wiring region. Therefore, it is possible to suppress a rapid change in deformability of the base material at or near the boundary between the functional member region and the first wiring region and/or the second wiring region. This can prevent the first wiring and/or the second wiring from being damaged at or near the boundary between the functional member region and the first wiring region and/or the second wiring region.

Further, in the case where the stretchable wiring board of the present disclosure has a supporting base material between the base material and the first wiring, and the second expansion/contraction control part is positioned between the supporting base material and the base material. Alternatively, the second expansion/contraction control part may be configured such that the Young's modulus of the second part of the second expansion/contraction control part is smaller than the Young's modulus of the first part. In this case, the second expansion/contraction control section can be composed of a member that can function as an adhesive that joins the supporting base material and the base material.

The second expansion/contraction control part 42 may lean against the functional member 6 as shown in FIG. 23(c). In this case, when the peak portion of the bellows-shaped portion provided with the second expansion/contraction control portion 42 is further displaced toward the functional member region 23, the second expansion/contraction control portion 42 leaning against the functional member 6 is compressed and a repulsive force is generated. Therefore, it is possible to suppress an increase in the height of the ridges of the bellows-shaped portion provided with the second expansion/contraction control portion. Thereby, it is possible to suppress damage to the connecting portion between the functional member and the first wiring and/or the second wiring. In addition, as shown in FIG. 23(c), the second expansion/contraction control section 42 may indirectly lean on the functional member 6 via other second expansion/contraction control sections or the like. No, but you may lean directly on the functional member.

The second expansion/contraction control part may be positioned on the first surface side of the base material, may be positioned on the second surface side of the base material, or may be positioned inside the base material.

When the second expansion/contraction control portion is located on the first surface side of the base material, the second expansion/contraction control portion 42 is provided for the interlayer insulating layer 4 of the second wiring 5 as shown in FIG. 15(b), for example. It may be located on the surface opposite to the side surface, or may be located between the base material 2 and the first wiring (not shown) as shown in FIG. 24(a). When the second expansion/contraction control part is positioned between the base material and the first wiring, the second expansion/contraction control part may be positioned on the first surface of the base material. It may be positioned in a recess provided on one surface. Further, when the stretchable wiring board of the present disclosure has a supporting base material between the base material and the first wiring, the second expansion/contraction control part is provided on the side opposite to the interlayer insulating layer side of the second wiring. It may be positioned on the plane, may be positioned between the supporting substrate and the first wiring, or may be positioned between the substrate and the supporting substrate.

When the second expansion/contraction control section is located inside the base material, the second expansion/contraction control section 42 is embedded inside the base material 2, as shown in FIG. 24(b), for example. Such a base material and the second expansion/contraction control part are used, for example, when the base material is produced by a so-called cast molding method in which an elastomer is injected into a mold and molded, and the second expansion/contraction control part is placed in the mold. Obtained by throwing in at the right time.

When the second expansion/contraction control section is located on the second surface side of the base material, the second expansion/contraction control section 42 may be configured separately from the base material, for example, as shown in FIG. Alternatively, they may be configured integrally as shown in FIGS. 24(d) and (e). When the second expansion/contraction control part is integrally formed with the base material, the second expansion/contraction control part 42 protrudes from the second surface 2b of the base material 2, as shown in FIG. 24(e), for example. It may be a convex portion, which appears in the functional member peripheral region 25 by forming a concave portion in the second wiring region 22 around the functional member peripheral region 25 as shown in FIG. may The term "integral" means that there is no interface between the base material and the second expansion/contraction control section.

The position of the second expansion/contraction control part in the normal direction of the first surface of the base material may be the same as the position of the first expansion/contraction control part in the normal direction of the first surface of the base material. can be different.

The second expansion/contraction control part may be positioned at least in the functional member peripheral region and should extend to the boundary between the functional member peripheral region and the functional member region. For example, as shown in FIG. 15(b), the second expansion/contraction control part 42 extends to the functional member region 23 beyond the boundary between the functional member peripheral region 25 and the functional member region 23. , and may extend over the entire functional member region 23 . For example, as shown in FIG. 25( a ), the second expansion/contraction control part 42 has a frame shape extending along the boundary between the functional member peripheral region 25 and the functional member region 23 in plan view. It may have a shape.

Also, the second expansion/contraction control part may have different shapes depending on the position. For example, as shown in FIG. 25(b), the second expansion/contraction control part 42 positioned in the functional member region 23 has a rectangular shape, and the second expansion/contraction control part 42 positioned in the functional member peripheral region 25 is It may have a circular shape.

The functional member surrounding area is an area located around the functional member area. The region around the functional member is a region where the second expansion/contraction control section is provided in order to suppress concentration of stress on the boundary between the functional member and the first wiring and/or the second wiring. . The dimensions of the functional member peripheral region are determined so as to be able to suppress concentration of stress on the boundary between the functional member and the first wiring and/or the second wiring.

The area of the functional member peripheral region may be, for example, 1/4 or more of the area of the functional member region, or may be 1/2 or more of the area of the functional member region. Also, the area of the functional member peripheral region can be, for example, equal to or less than the area of the functional member region, and may be 3/4 or less of the area of the functional member region.

The functional member peripheral region may be defined as a region within a certain distance from the end of the functional member. The functional member peripheral region can be, for example, a region within 5 mm from the end of the functional member, and may be a region within 2 mm.

Note that the functional member region may be provided with a member for suppressing deformation of the functional member region, which is different from the second expansion/contraction control section.

10. Adhesive layer The elastic wiring board of the present disclosure may have an adhesive layer on the surface opposite to the surface of the second wiring and the functional member on the interlayer insulating layer side, or on the second surface of the base material. good. The adhesive layer is provided for attaching the stretchable wiring board of the present disclosure to an object such as a human body.

The adhesive layer does not have a bellows-shaped portion because it is usually disposed after forming wiring having a bellows-shaped portion.

The adhesive layer is not particularly limited, and a general adhesive can be used, and is appropriately selected according to the application of the stretchable wiring board. For example, acrylic adhesives, silicone adhesives, urethane adhesives, rubber adhesives, and the like can be used.

The thickness of the adhesive layer may be any thickness that is stretchable and that allows the stretchable wiring board to be attached to an object, and is appropriately selected according to the application of the stretchable wiring board. The thickness of the adhesive layer can be, for example, within the range of 10 μm or more and 100 μm or less.

Also, a release layer may be positioned on the surface of the adhesive layer opposite to the surface facing the substrate. A common release layer can be used.

Examples of the method of arranging the adhesive layer include a method of applying an adhesive, and a method of preparing an adhesive film having an adhesive layer on one side of the release layer and laminating the adhesive layer side surface of the adhesive film. be done.

11. Applications Since the stretchable wiring board of the present disclosure has stretchability, it can be applied to a curved surface and can follow deformation. Due to such advantages, the stretchable wiring substrate of the present disclosure can be used for wearable devices, medical equipment, robots, and the like, for example.
The stretchable wiring board of the present disclosure may be used, for example, by attaching it to human skin, or may be used by attaching it to a wearable device or a robot.

12. Other Embodiments In another embodiment of the stretchable wiring board of the present disclosure, even if a difficult-to-stretch portion having a Young's modulus larger than that of the substrate is located between the first wiring and the second wiring. good. In this case, the interlayer insulating layer can be an arbitrary member. Due to the hard-to-stretch portion being positioned between the first wiring and the second wiring, the first wiring and the second wiring are damaged or the first wiring is damaged in the intersection region where the first wiring and the second wiring intersect. It is possible to suppress the occurrence of insulation failure between the first wiring and the second wiring.

B. Method for manufacturing stretchable wiring board The method for manufacturing a stretchable wiring board according to the present disclosure comprises a preparatory step of preparing a laminate having a first wiring, an interlayer insulating layer and a second wiring in this order; an elongation step of applying a tensile stress to elongate the base material; a wiring arrangement step of arranging the first wiring side surface of the laminate on the first surface side of the base material in the elongated state; A connection portion of the first wiring or the second wiring is arranged on the first surface side of the base material, on the second surface side opposite to the first surface of the base material, or inside the base material. a difficult-to-stretch portion arranging step of arranging a difficult-to-stretch portion in the connecting region where the first wiring and the second wiring are connected; and a relaxing step of removing the tensile stress from the base material. has a bellows-shaped portion in which peaks and valleys in the normal direction of the first surface of the base material repeatedly appear along the in-plane direction of the first surface of the base material, and the interlayer Young's modulus of the insulating layer is smaller than Young's modulus of the first wiring and the second wiring, Young's modulus of the hard-to-stretch portion is larger than Young's modulus of the base material, and Young's modulus of the interlayer insulating layer is larger than that of the base material. rate or higher.

FIGS. 26A to 26E are process diagrams showing an example of the method for manufacturing the stretchable wiring board of the present disclosure. First, as shown in FIG. 26( a ), the first wiring 3 , the interlayer insulating layer 4 and the second wiring 5 are arranged in order on one surface of the supporting substrate 7 to fabricate a laminate. Further, as shown in FIG. 26(b), on the first surface 2a of the elastic base material 2, the connecting portion 9 of the first wiring 3 and the second wiring 5 shown in FIG. 26(a) is The hard-to-stretch portion 11 is arranged in a region corresponding to the connecting region 24 located. Next, as shown in FIGS. 26(b) to 26(c), the stretchable base material 2 is stretched. This step is also referred to as pre-stretching the stretchable base material. Next, as shown in FIG. 26(d), the adhesive layer 8 is applied to the first surface 2a of the base material 2 so that the hard-to-stretch portion 11 is located in the connection region 24 while the base material 2 is stretched. The surface of the laminate on the side of the supporting base material 7 is bonded together. Subsequently, as shown in FIG. 26(e), the tensile stress of the substrate 2 is removed. At this time, as the elastic base material 2 shrinks, the supporting base material 7, the first wiring 3, the interlayer insulating layer 4 and the second wiring 5 are deformed to have a bellows-shaped portion. Thereby, the stretchable wiring board 1 is obtained. In the example shown in FIGS. 26(a) to (e), the elongation step, the hard-to-stretch portion placement step, and the wiring placement step are performed in this order.

27(a) to (f) are process diagrams showing another example of the method for manufacturing the stretchable wiring board of the present disclosure. First, as shown in FIG. 27( a ), the first wiring 3 , the interlayer insulating layer 4 and the second wiring 5 are arranged in this order on one surface of the supporting base material 7 . Subsequently, as shown in FIG. 27B, the hard-to-stretch portion 11 is arranged on the second wiring 5 in the connection region 24 where the connection portion 9 of the first wiring 3 and the second wiring 5 is located. to produce a laminate. Further, as shown in FIGS. 27(c) to (d), the stretchable base material 2 is stretched. Next, as shown in FIG. 27( e ), in a state where the base material 2 is stretched, a surface of the support base material 7 side of the laminate is applied to the first surface 2 a of the base material 2 via the adhesive layer 8 . are pasted together. Subsequently, as shown in FIG. 27(f), the tensile stress of the substrate 2 is removed. At this time, as the elastic base material 2 shrinks, the supporting base material 7, the first wiring 3, the interlayer insulating layer 4 and the second wiring 5 are deformed to have a bellows-shaped portion. Thereby, the stretchable wiring board 1 is obtained. In the example shown in FIGS. 27(a) to (f), the elongation process, the wiring arrangement process, and the hard-to-stretch portion arrangement process are performed simultaneously.

Each step in the method for manufacturing a stretchable wiring board according to the present disclosure will be described below.

1. Preparing Step A preparing step in the present disclosure is a step of preparing a laminate having a first wiring, an interlayer insulating layer and a second wiring in this order. The Young's modulus of the interlayer insulating layer is smaller than the Young's moduli of the first wiring and the second wiring.

The laminate can have a supporting substrate, and in this case, has a first wiring, an interlayer insulating layer and a second wiring in this order on one surface of the supporting substrate.
The method for forming the first wiring, the interlayer insulating layer, and the second wiring is described in the above section "A. Stretchable wiring board", so the description is omitted here.

Moreover, the laminate can have a functional member on one surface of the supporting substrate. The method of arranging the functional members can be, for example, the same as a general mounting method on a circuit board.

Moreover, the laminated body has a connecting portion for the first wiring or the second wiring, and may have a difficult-to-stretch portion located in the connecting region.
Since the method for forming the difficult-to-stretch portion was described in the above section "A. Stretchable wiring board", description thereof will be omitted here.

2. Elongation Step The elongation step in the present disclosure is a step of applying tensile stress to a stretchable base material to elongate the base material.

When stretching the substrate, it may be stretched uniaxially or biaxially, for example.

In the elongation step, the base material is preferably elongated by 20% (1.2 times the initial length) or more based on the normal state (non-elongated state), and 30% (1.3 times the initial length). times) or more, and more preferably 50% (1.5 times the initial length) or more. In addition, the upper limit of the elongation rate of the substrate is about 200%. Stretchable first wiring and second wiring can be obtained by stretching the base material within the above range.

3. Wiring Arranging Step The wiring arranging step in the present disclosure is a step of arranging the first wiring side surface of the laminate on the first surface side of the base material in an extended state.

In the wiring arrangement step, for example, the first wiring side surface of the laminate can be arranged on the first surface side of the stretched base material via an adhesive layer.
Since the adhesive layer was described in the above section "A. Elastic wiring board 2. First wiring and second wiring", description thereof will be omitted here.

4. Hard-to-stretch portion arranging step In the hard-to-stretch portion arranging step in the present disclosure, on the first surface side of the base material, the second surface side opposite to the first surface of the base material, or inside the base material, Also, it is a step of arranging a hard-to-stretch portion in a connection region where a connection portion of the first wiring or the second wiring is arranged. The Young's modulus of the hard-to-stretch portion is greater than the Young's modulus of the substrate and equal to or higher than the Young's modulus of the interlayer insulating layer.

The hard-to-stretch portion arranging step and the wiring arranging step can be performed in random order. Moreover, the hard-to-stretch portion arranging step and the stretching step can be performed in random order.

When the hard-to-stretch part is arranged on the first surface side of the base material, the difficult-to-stretch part may be arranged on the surface opposite to the surface of the second wiring on the interlayer insulating layer side. You may arrange|position between wiring and may arrange|position between a base material and a support base material.

When the difficult-to-stretch part is arranged on the surface of the second wiring opposite to the surface facing the interlayer insulating layer, the difficult-to-stretch part may be arranged on the second wiring in the preparation step, and after the wiring arrangement step , You may arrange|position a hard-to-stretch part on a 2nd wiring in the state which extended|stretched the said base material. In the preparatory step, when the difficult-to-stretch portion is arranged on the second wiring, the wiring placement step and the difficult-to-stretch portion placement step can be performed at the same time. Further, when the hard-to-stretch portion is arranged on the second wiring while the base material is stretched after the wiring-arranging step, the wiring-arranging step and the hard-to-stretch portion arranging step can be performed in this order.

Moreover, when the difficult-to-stretch part is arranged between the supporting base material and the first wiring, the difficult-to-stretch part can be arranged on the supporting base material in the above preparation step. In this case, the wiring placement step and the hard-to-stretch portion placement step can be performed simultaneously.

Further, when the difficult-to-stretch portion is arranged between the substrate and the supporting substrate, the difficult-to-stretch portion may be arranged on the first surface of the substrate before the elongation step, and after the elongation step, the The hard-to-stretch part may be arranged on the first surface of the base material in a state where the base material is stretched. Usually, the hard-to-stretch portion is arranged on the first surface of the substrate before the elongation step. In this case, the difficult-to-stretch portion arranging step and the wiring arranging step can be performed in this order.

Further, when the hard-to-stretch part is arranged on the first surface of the base material before the elongation step, the hard-to-stretch part may be arranged on the first surface of the base material after preparing the base material in advance, Alternatively, when the method for manufacturing the base material is cast molding, a base material having a difficult-to-stretch portion on the first surface may be manufactured in the manufacturing process of the base material. In this case, the manufacturing process of the base material becomes the hard-to-stretch portion arranging process.

In addition, when the method for manufacturing the substrate is a cast molding method and a substrate having a difficult-to-stretch portion on the first surface is produced in the manufacturing process of the substrate, for example, the difficult-to-stretch portion is formed on the bottom surface of the mold. After arranging, a method of injecting elastomer into a mold and molding can be used. In this case, the first surface side of the substrate can be a flat surface. Therefore, it is possible to eliminate the step due to the hard-to-stretch portion, and prevent disconnection of the first wiring and the second wiring due to the step.

In the above case, before arranging the hard-to-stretch part on the bottom surface of the mold, by placing the release layer and the adhesive layer in this order on the bottom surface of the mold, the hard-to-stretch part and the adhesion A second laminate may be made having a layer and a release layer in that order.
FIGS. 28(a) to (f) and FIGS. 29(a) to (c) are process diagrams showing another example of the method for manufacturing the stretchable wiring board of the present disclosure. First, as shown in FIG. 28A, the release layer 52 and the adhesive layer 8 are arranged in this order on the bottom surface of the mold 51 . Next, as shown in FIG. 28(b), the difficult-to-stretch portion 11 is arranged on the adhesive layer 8 in a region corresponding to the connection region where the connection portions of the first wiring and the second wiring are located. Next, as shown in FIG. 28(c), the elastomer is poured into a mold 51 and solidified, and then removed from the mold 51 as shown in FIG. 28(d). As a result, a second laminate having the hard-to-stretch portion 11, the adhesive layer 8 and the release layer 52 in this order on the first surface 2a of the substrate 2 is obtained. Next, the release layer 52 is peeled off from the second laminate, and the stretchable substrate 2 is stretched as shown in FIGS. 28(e) to (f). Further, as shown in FIG. 29A, separately, the first wiring 3, the interlayer insulating layer 4 and the second wiring 5 are arranged in order on one surface of the supporting substrate 7 to fabricate a laminate. Next, as shown in FIG. 29( b ), with the base material 2 stretched, the surface of the adhesive layer 8 of the second laminate is placed so that the hard-to-stretch portion 11 is positioned in the connection region 24 . , the surface of the laminate on the side of the supporting substrate 7 is laminated. Subsequently, as shown in FIG. 29(c), the tensile stress of the substrate 2 is removed. At this time, as the elastic base material 2 shrinks, the supporting base material 7, the first wiring 3, the interlayer insulating layer 4 and the second wiring 5 are deformed to have a bellows-shaped portion. Thereby, the stretchable wiring board 1 is obtained. In the examples shown in FIGS. 28(a) to (f) and FIGS. 29(a) to (c), the hard-to-stretch portion arranging step, the stretching step, and the wiring arranging step are performed in this order.

When the difficult-to-stretch part is arranged on the second surface side of the base material, the difficult-to-stretch part may be arranged on the second surface of the base material before the elongation step, and the base material is elongated after the elongation step. In this state, the difficult-to-stretch portion may be arranged on the second surface of the base material. Usually, the difficult-to-stretch portion is arranged on the second surface of the substrate before the elongation step. In this case, the difficult-to-stretch portion arranging step and the wiring arranging step can be performed in this order.

Further, when the hard-to-stretch portion is arranged on the second surface of the substrate before the elongation step, the hard-to-stretch portion may be arranged on the second surface of the substrate after preparing the substrate in advance, Alternatively, when the manufacturing method of the base material is the cast molding method, the base material having the hard-to-stretch portion on the second surface may be manufactured in the manufacturing process of the base material. In this case, the manufacturing process of the base material becomes the hard-to-stretch portion arranging process.

When the hard-to-stretch part is arranged inside the base material, the hard-to-stretch part can be embedded inside the base material in the manufacturing process of the base material before the elongation process. In this case, the difficult-to-stretch portion arranging step and the wiring arranging step can be performed in this order.

The method for forming the difficult-to-stretch portion is described in the above section "A. Stretchable wiring board", so the description is omitted here.

5. Relaxation Step The relaxation step in the present disclosure is the step of removing the tensile stress from the substrate. By performing this step, the base material shrinks, deformation occurs in the first wiring, the interlayer insulating layer and the second wiring, and at least one of the first wiring and the second wiring comes to have a bellows-shaped portion. At this time, the connection region is provided with a difficult-to-stretch portion having a Young's modulus greater than that of the base material and equal to or higher than that of the interlayer insulating layer, thereby suppressing damage to the connection. be able to.

6. Other Steps In the method for manufacturing a stretchable wiring board according to the present disclosure, after the elongation step and before the relaxation step, the first surface of the base material is placed on the first surface side of the base material or the second surface side of the base material while the base material is stretched. can have a first expansion/contraction control portion arrangement step of arranging the expansion/contraction control portion. In this case, the wiring arrangement process, the hard-to-stretch portion arrangement process, and the first expansion/contraction control section arrangement process can be performed in any order.
Further, in the elastic wiring board of the present disclosure, when the first expansion/contraction control part is embedded inside the base material, as described above, the base material containing the first expansion/contraction control part is obtained in advance. be able to.

Further, the method for manufacturing a stretchable wiring board according to the present disclosure may have an adhesive layer placement step of placing an adhesive layer after the relaxation step.

The present disclosure is not limited to the above embodiments. The above embodiment is an example, and any device that has substantially the same configuration as the technical idea described in the claims of the present disclosure and produces similar effects is the present invention. It is included in the technical scope of the disclosure.

Examples and comparative examples are shown below to describe the present disclosure in more detail.

[Example 1]
(Preparation of stretchable base material)
An adhesive sheet (manufactured by 3M, model number 8146) is used as an adhesive layer, and two-liquid addition-condensation polydimethylsiloxane (PDMS) is applied to the adhesive sheet to a thickness of 900 μm, and the PDMS is cured to form an adhesive layer. and a first laminate of the stretchable substrate.

(Formation of first wiring)
A polyethylene naphthalate (PEN) film with a thickness of 2.5 μm was used as a support substrate, and Cu with a thickness of 1 μm was sputtered on the PEN film, and a first wiring with a width of 200 μm and a length of 40 mm was provided by photolithography. rice field.

(Formation of interlayer insulating layer)
Urethane paste is screen-printed on the first wiring so as to be located in the intersection region where the first wiring and the second wiring intersect, forming an interlayer insulating layer of urethane resin with a thickness of 10 μm, a width of 1 mm, and a length of 1 mm. did.

(Formation of second wiring)
Ag paste containing Ag particles and elastomer was screen-printed to cross the first wiring and located on the interlayer insulating layer to form a second wiring having a thickness of 20 μm, a width of 200 μm, and a length of 40 mm. established. As a result, a second laminate of the supporting substrate, the first wiring, the interlayer insulating layer and the second wiring was obtained.

Here, the Young's modulus of the elastic base material of PDMS, the supporting base material of PEN, the interlayer insulating layer of urethane resin, the first wiring of Cu, and the second wiring containing Ag particles and elastomer is as follows. Met.
Stretchable substrate <interlayer insulating layer <second wiring <supporting substrate <first wiring

(Production of stretchable wiring board)
In a state in which the first laminate is stretched uniaxially by 50%, the adhesive layer side surface of the first laminate is arranged so that the stretching direction of the elastic base material and the extending direction of the first wiring are parallel. Then, the surface of the second laminate on the side of the supporting substrate was laminated. At this time, the resistance of the first wiring was 5Ω, and the resistance of the second wiring was 43Ω.
The stretchable substrate was then contracted by releasing the stretch. As a result, the surface of the supporting base material became uneven and shrunk. At this time, the resistance of the first wiring was 5.2Ω, and the resistance of the second wiring was 55Ω. Also, at this time, no short circuit or disconnection was observed in the first wiring and the second wiring.
Further, when the stretchable wiring board was subjected to a 30% stretch test, disconnection occurred after 3100 cycles.

[Example 2]
In the production of the second laminate, after the formation of the second wiring, a striped expansion control part of urethane resin having a thickness of 30 μm and L/S=200 μm/200 μm is screened so as to intersect with the extending direction of the first wiring. A first laminate and a second laminate were produced in the same manner as in Example 1, except that they were formed by printing.

In a state in which the first laminate is stretched uniaxially by 50%, the adhesive layer side surface of the first laminate is arranged so that the stretching direction of the elastic substrate and the extending direction of the first wiring are parallel. Then, the support substrate side surface of the second laminate was laminated. At this time, the resistance of the first wiring was 5Ω, and the resistance of the second wiring was 44Ω.

The stretchable substrate was then contracted by releasing the stretch. As a result, the surface of the supporting base material became uneven and shrunk. At this time, the resistance of the first wiring was 5.1Ω, and the resistance of the second wiring was 52Ω. Also, at this time, no short circuit or disconnection was observed in the first wiring and the second wiring.
Further, when the elastic wiring board was subjected to a 30% repeated expansion/contraction test, disconnection occurred at 7200 times.

[Example 3]
In the production of the second laminate, the same procedure as in Example 1 was performed except that after forming the second wiring, a urethane resin adjustment layer having a thickness of 10 μm was formed so as to cover the first wiring and the second wiring. , a first laminate and a second laminate were produced.
Here, the magnitude relationship between the Young's moduli of the first wiring, the second wiring, and the adjustment layer was as follows.
Adjustment layer < second wiring < first wiring

In a state in which the first laminate is stretched uniaxially by 50%, the adhesive layer side surface of the first laminate is arranged so that the stretching direction of the elastic substrate and the extending direction of the first wiring are parallel. Then, the support substrate side surface of the second laminate was laminated. At this time, the resistance of the first wiring was 5Ω, and the resistance of the second wiring was 41Ω.

The stretchable substrate was then contracted by releasing the stretch. As a result, the surface of the supporting base material became uneven and shrunk. At this time, the resistance of the first wiring was 5.1Ω, and the resistance of the second wiring was 50Ω. Also, at this time, no short circuit or disconnection was observed in the first wiring and the second wiring.
Further, when the elastic wiring board was subjected to a 30% repeated expansion/contraction test, disconnection was not observed even after expansion/contraction 10,000 times.

[Comparative example]
A first laminate and a second laminate were produced in the same manner as in Example 1, except that an acrylic resin interlayer insulating layer was formed by photolithography using an acrylic paste in the formation of the interlayer insulating layer. .

In this case, the Young's modulus of the elastic base material of PDMS, the supporting base material of PEN, the interlayer insulating layer of acrylic resin, the first wiring of Cu, and the second wiring containing Ag particles and elastomer is as follows. Met.
Stretchable substrate <second wiring <interlayer insulating layer <supporting substrate <first wiring

While the first laminate was stretched uniaxially by 50%, the supporting substrate side surface of the second laminate was laminated to the adhesive layer side surface of the first laminate. At this time, the resistance of the first wiring was 4.8Ω, and the resistance of the second wiring was 47Ω.
The stretchable substrate was then contracted by releasing the stretch. As a result, the surface of the supporting base material became uneven and shrunk. At this time, cracks were observed in the interlayer insulating layer, and disconnection of the first wiring was observed.

DESCRIPTION OF SYMBOLS 1... Elastic wiring board 2... Elastic base material 2a... First surface of elastic base material 2b... Second surface of elastic base material 3... First wiring 4... Interlayer insulating layer 5... 2nd wiring 7 ... support base material 8 ... adhesive layer 9 ... connection part 11 ... difficult-to-stretch part 12 ... adjustment layer 20 ... intersection region 21 ... first wiring region 22 ... second wiring region 23 ... functional member region 24 ... connection Area 25... Functional member surrounding area 30... Accordion-shaped portion 31, 33, 35, 37... Mountain portion 32, 34, 36, 38... Valley portion 41... First expansion/contraction control section 42... Second expansion/contraction control section

Claims (19)

Having a first wiring, an interlayer insulating layer, and a second wiring in this order on a first surface of a base material having elasticity,
The substrate has peaks and valleys in the normal direction of the first surface, and the peaks and valleys appear repeatedly along the in-plane direction of the first surface of the substrate. has a bellows-shaped portion of
at least one of the first wiring and the second wiring has a bellows-shaped portion of the wiring that appears along the bellows-shaped portion of the substrate;
Young's modulus of the interlayer insulating layer is smaller than Young's modulus of the first wiring and the second wiring,
An elastic wiring board , wherein the Young's modulus of the interlayer insulating layer is higher than the Young's modulus of the base material . 2. The stretchable wiring board according to claim 1 , wherein said first wiring is a metal film. 3. The stretchable wiring board according to claim 1 , wherein said second wiring contains conductive particles and an elastomer. The second wiring has a portion located on the interlayer insulating layer and a portion located on the same plane as the first wiring, and the portion of the second wiring located on the interlayer insulating layer comprises: 4. The stretchable wiring board according to claim 3 , containing conductive particles and an elastomer. Located on the first surface side of the base material, on the second surface side opposite to the first surface of the base material, or inside the base material, and connecting the first wiring or the second wiring further having a difficult-to-stretch part located in the connection area where the part is located,
The stretchable wiring board according to any one of claims 1 to 4 , wherein a Young's modulus of the hard-to-stretch portion is larger than that of the base material and equal to or higher than that of the interlayer insulating layer. . The hard-to-stretch portions are located in a first connection region where the connection portion between the first wiring and the second wiring is located, and the connection portion between the first wiring or the second wiring and the functional member are located. 6. The stretchable wiring board according to claim 5 , which is located over the second connection area. Having a first wiring, an interlayer insulating layer, and a second wiring in this order on a first surface of a base material having elasticity,
The substrate has peaks and valleys in the normal direction of the first surface, and the peaks and valleys appear repeatedly along the in-plane direction of the first surface of the substrate. has a bellows-shaped portion of
at least one of the first wiring and the second wiring has a bellows-shaped portion of the wiring that appears along the bellows-shaped portion of the substrate;
Young's modulus of the interlayer insulating layer is smaller than Young's modulus of the first wiring and the second wiring,
Located on the first surface side of the base material, on the second surface side opposite to the first surface of the base material, or inside the base material, and connecting the first wiring or the second wiring further having a difficult-to-stretch part located in the connection area where the part is located,
The Young's modulus of the hard-to-stretch portion is greater than the Young's modulus of the base material and equal to or higher than the Young's modulus of the interlayer insulating layer,
The stretchable wiring board, wherein the hard-to-stretch portion includes a first portion and a second portion having higher deformability than the first portion. The hard-to-stretch portions are located in a first connection region where the connection portion between the first wiring and the second wiring is located, and the connection portion between the first wiring or the second wiring and the functional member are located. 8. The stretchable wiring board according to claim 7 , which is located over the second connection area. 9. The stretchable wiring board according to claim 7 , wherein the thickness of said second portion of said difficult-to-stretch portion is at least partially reduced with increasing distance from said first portion. The elastic wiring according to any one of claims 7 to 9 , wherein the Young's modulus of the second portion of the hard-to-stretch portion is smaller than the Young's modulus of the first portion of the hard-to-stretch portion. substrate. The stretchable wiring board according to any one of claims 7 to 10, wherein the density distribution of said second portion of said hard-to-stretch portion is smaller than the density distribution of said first portion of said hard-to-stretch portion. The elastic wiring according to any one of claims 1 to 11, further comprising a functional member located on the first surface side of the base material and connected to the first wiring or the second wiring. substrate. The stretchable wiring board according to any one of claims 1 to 12, further comprising a supporting base material between the base material and the first wiring. A first wiring region located between the surface of the second wiring opposite to the surface of the interlayer insulating layer, or between the base material and the first wiring and where the first wiring is located, and the first wiring. further comprising an adjustment layer located in a second wiring region where two wirings are located and having the bellows-shaped portion;
14. The stretchable wiring board according to any one of claims 1 to 13, wherein the Young's modulus of the adjustment layer is smaller than the Young's modulus of the first wiring and the second wiring. Having a first wiring, an interlayer insulating layer, and a second wiring in this order on a first surface of a base material having elasticity,
The substrate has peaks and valleys in the normal direction of the first surface, and the peaks and valleys appear repeatedly along the in-plane direction of the first surface of the substrate. has a bellows-shaped portion of
at least one of the first wiring and the second wiring has a bellows-shaped portion of the wiring that appears along the bellows-shaped portion of the base;
Young's modulus of the interlayer insulating layer is smaller than Young's modulus of the first wiring and the second wiring,
A first wiring region located between the surface of the second wiring opposite to the surface of the interlayer insulating layer, or between the base material and the first wiring and where the first wiring is located, and the first wiring. further comprising an adjustment layer located in a second wiring region where two wirings are located and having the bellows-shaped portion;
Young's modulus of the adjustment layer is smaller than Young's modulus of the first wiring and the second wiring,
An elastic wiring board, wherein the Young's modulus of the adjustment layer is higher than that of the base material. a preparation step of preparing a laminate having a first wiring, an interlayer insulating layer and a second wiring in this order;
An elongation step of applying a tensile stress to a stretchable base material to elongate the base material;
a wiring arrangement step of arranging the surface of the laminate on the side of the first wiring on the first surface side of the base material in a stretched state;
A connection portion of the first wiring or the second wiring is provided on the first surface side of the base material, on the second surface side opposite to the first surface of the base material, or inside the base material. a difficult-to-stretch portion arranging step of arranging a difficult-to-stretch portion in the connection region to be arranged;
a relaxing step to remove the tensile stress from the substrate;
After the relaxation step, at least one of the first wiring and the second wiring has peaks and valleys in the normal direction of the first surface of the base material, and is in the in-plane direction of the first surface of the base material. has a bellows-shaped portion that repeatedly appears along the
Young's modulus of the interlayer insulating layer is smaller than Young's modulus of the first wiring and the second wiring,
A method for producing a stretchable wiring board, wherein the Young's modulus of the difficult-to-stretch portion is greater than that of the base material and equal to or higher than that of the interlayer insulating layer. Before the elongation step, the difficult-to-stretch portion arranging step is performed,
The method for forming the base material is a cast molding method,
In the difficult-to-stretch portion arranging step, after placing the difficult-to-stretch portion on the bottom surface of the mold, the hard-to-stretch portion is formed on the first surface or the second surface by injecting an elastomer into the mold and molding. 17. The method for manufacturing an elastic wiring board according to claim 16, wherein the base material having In the difficult-to-stretch portion arranging step, before arranging the difficult-to-stretch portion on the bottom surface of the mold, a release layer and an adhesive layer are arranged in this order on the bottom surface of the mold, so that the first surface of the base material , producing a second laminate having the difficult-to-stretch portion, the adhesive layer and the release layer in this order,
After peeling the release layer of the second laminate, performing the elongation step,
18. The method for manufacturing an elastic wiring board according to claim 17, wherein in the wiring arrangement step, the surface of the laminate on the side of the first wiring is bonded to the surface of the adhesive layer of the second laminate. In the preparing step, preparing the laminate having the first wiring, the interlayer insulating layer and the second wiring in this order on one surface of a supporting base;
19. The expansion and contraction according to any one of claims 16 to 18, wherein in the wiring arrangement step, the surface of the laminate on the side of the support substrate is arranged on the first surface side of the substrate in an extended state. A method for manufacturing a flexible wiring board.

Images