Resin wiring board and stretchable device

Abstract

A resin wiring board (10) comprises: a metal foil wiring pattern (21) composed of a metal foil containing copper as a main component; and an elastic resin base material (11) disposed so as to sandwich the metal foil wiring pattern from above and below, wherein an elongation at break of the elastic resin base material (11) is 200% or more.

Description

Resin wiring boards and stretchable devices

[0001] This disclosure relates to resin wiring substrates and stretchable devices. This application claims priority under Japanese Patent Application No. 2025-019304, filed in Japan on February 7, 2025, the contents of which are incorporated herein by reference.

[0002] Wearable devices are attracting attention in a wide range of fields, including sports science and healthcare. Wearable devices are preferably designed for comfortable, stress-free wear. Therefore, it is desirable that they be stretchable to accommodate the object they are worn on. In this specification, devices possessing such characteristics are referred to as stretchable devices, not limited to their use as wearable devices.

[0003] Conventionally, rigid and hard plastics such as polyimide (PI), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polycarbonate (PC), cellulose triacetate (TAC), and cellulose acetate propionate (CAP) have been known as materials used for printed circuit boards. Printed circuit boards made from these materials do not return to their original shape when bent, and the metal wiring may peel off or break due to stress from the board.

[0004] Patent Document 1 describes an epoxy resin sheet that exhibits recovery after stretching, with a hysteresis loss of 40% or less after maintaining a 50% elongation in tensile mode for 2 seconds, as measured according to JIS K 7312:1996. Patent Document 1 also describes stretchable and flexible members equipped with epoxy resin sheets.

[0005] Patent Document 2 describes a bendable wiring substrate comprising a film made of polyurethane that can be synthesized by reacting a long-chain polyol with a polyisocyanate, wherein the temperature at which the storage modulus becomes 1 MPa by dynamic viscoelastic measurement is 155°C or higher, the storage modulus at 25°C is 20 to 200 MPa, the tensile strength is 20 to 80 MPa, and the elongation at break is 500 to 900%, and circuit wiring formed in contact with the surface of the film.

[0006] Patent Document 3 describes a stretchable conductive substrate comprising a sheet-like stretchable base material, a stretchable conductive pattern formed on one side of the stretchable base material, and a substrate that is used by folding it.

[0007] Japanese Patent Publication No. 2023-32668, International Publication No. 2020 / 090634, Japanese Patent Publication No. 2017-22173

[0008] For stretchable devices, it is preferable that the stretchable wiring board has high flexibility, returning to its original shape even after repeated bending. Conventional stretchable wiring boards do not have sufficient flexibility.

[0009] This disclosure has been made in view of the above-mentioned problems, and aims to provide a resin wiring substrate having high flexibility, and a stretchable device equipped therewith.

[0010] To solve the above problems, the following means are provided.

[0011] One aspect of the present disclosure is a resin wiring substrate comprising a metal foil wiring pattern made of a metal foil mainly composed of copper, and a stretchable resin substrate arranged to sandwich the metal foil wiring pattern from above and below, wherein the stretchable resin substrate has a break elongation rate of 200% or more.

[0012] Aspect 2 of the present disclosure is a resin wiring substrate according to aspect 1, wherein the metal foil wiring pattern is located in a range of 5% to 50% of the total thickness of the substrate from the surface facing inward in the bending direction.

[0013] Aspect 3 of this disclosure is a resin wiring board according to aspect 1 or aspect 2, wherein the Young's modulus of the stretchable resin substrate is 30 N / mm². ２ The following applies:

[0014] Aspect 4 of the present disclosure is a resin wiring substrate in any one of aspects 1 to 3, wherein the thickness of the metal foil wiring pattern is 50 μm or less, and the thickness of the stretchable resin substrate is 50 μm or more.

[0015] Embodiment 5 of this disclosure is a stretchable device comprising a resin wiring substrate from any one of Embodiments 1 to 4.

[0016] The resin wiring substrate of this disclosure provides a resin wiring substrate with high flexibility.

[0017] This is a schematic cross-sectional view showing an example of a resin wiring substrate of the present disclosure. This is a schematic plan view showing an example of a stretchable device of the present disclosure. This is a cross-sectional view of the stretchable device shown in Figure 2A, cut along the line B-B'. This is a schematic cross-sectional view showing a resin wiring substrate in a bent state. This is a schematic cross-sectional view of a resin wiring substrate 10 for indicating the position of a metal foil wiring pattern. This is a schematic cross-sectional view showing steps in the manufacturing method of a resin wiring substrate. This is a schematic cross-sectional view showing steps in the manufacturing method of a resin wiring substrate. These are the infrared absorption (IR) spectra of resin substrate 8 and resin substrate 18.

[0018] The resin wiring board and stretchable device of this embodiment will be described in detail below, with appropriate reference to the drawings. The drawings used in the following description may be enlarged for convenience to clearly illustrate the features of this disclosure. Therefore, the dimensional ratios of each component may differ from those of the actual components. The materials, dimensions, etc., exemplified in the following description are examples only, and this disclosure is not limited to them. It is possible to modify and implement these examples as appropriate without altering the essence of the invention.

[0019] [Stretchable Device] Figure 1 is a schematic cross-sectional view illustrating an example of a resin wiring board of this embodiment. Figure 2 shows a stretchable device comprising the resin wiring board of this disclosure shown in Figure 1, where Figure 2(a) is a schematic plan view and Figure 2(b) is a schematic cross-sectional view taken along the line B-B' shown in Figure 2(a). Note that Figure 1 is a schematic cross-sectional view taken along the line A-A' shown in Figure 2(a).

[0020] The stretchable device 100 of this embodiment, shown in Figures 2(a) and 2(b), comprises a stretchable resin wiring board 10. The resin wiring board 10 has a stretchable resin substrate 11 and a metal foil wiring pattern 21 formed on the stretchable resin substrate 11. The resin wiring board 10 and the stretchable resin substrate 11 of this embodiment have a strip shape. As shown in Figures 2(a) and 2(b), two electronic components 41 are arranged on the surface 11Aa of the stretchable resin substrate 11, which is positioned approximately at the center of the length of the resin wiring board 10.

[0021] (Stretchable resin substrate) The stretchable resin substrate 11 has a breaking elongation of 200% or more. The stretchable resin substrate 11 is in sheet form and has a Young's modulus of 30 N / mm². ２ Preferably, the following conditions apply: The Young's modulus of the stretchable resin substrate 11 is 20 N / mm². ２ More preferably, the following is preferred: 10 N / mm ２ The following is even more preferable, as it allows for the formation of a resin wiring substrate 10 that can create a stretchable device with even more comfortable wearability. The Young's modulus of the stretchable resin substrate 11 is 0.2 N / mm². ２ Preferably, the value is 0.4 N / mm². ２ The above is more preferable. This is because it makes it easier to obtain a resin wiring board 10 with good stretch durability, where the stretchability does not deteriorate even when repeatedly stretched and contracted.

[0022] Thickness of the stretchable resin substrate 11 (reference numeral t in Figure 3B) ＴThe thickness of the stretchable resin substrate 11 is preferably 20 μm to 400 μm. The lower limit of the thickness of the stretchable resin substrate 11 may be 30 μm, 40 μm, or 50 μm. The upper limit of the thickness of the stretchable resin substrate 11 may be 350 μm, 300 μm, 250 μm, 200 μm, 150 μm, or 100 μm.

[0023] The stretchable resin substrate 11 comprises a resin component made of a base material resin and a filler as needed. It is preferable that the stretchable resin substrate 11 contains a filler. The Young's modulus is 30 N / mm². ２ The stretchable resin substrate 11 described below tends to lose its elasticity when repeatedly stretched and contracted. However, if the stretchable resin substrate 11 contains a filler, it tends to have good stretch durability, meaning that its elasticity does not deteriorate easily even when repeatedly stretched and contracted.

[0024] "Resin for base material" Examples of resin components for the base material contained in the stretchable resin base material 11 include epoxy resins, urethane resins, urea resins, polyurethane urea resins, (meth)acrylic acid resins, polyacrylic resins, silicone resins, diene resins, polyester resins, polyether resins, polyamide resins, and polystyrene resins.

[0025] In this specification, "(meth)acrylic acid" is a concept that encompasses both "acrylic acid" and "methacrylic acid." Similarly, "(meth)acrylate" is a concept that encompasses both "acrylate" and "methacrylate." The same applies to terms similar to (meth)acrylate; for example, "(meth)acryloyl group" is a concept that encompasses both "acryloyl group" and "methacryloyl group."

[0026] The resin for the substrate preferably has one or more structural units selected from structural units derived from monomers, including a structural unit derived from a compound having a urethane bond and a polymerizable unsaturated bond (hereinafter sometimes referred to as a "urethane-derived structural unit"), a structural unit derived from a compound having a fluorene skeleton (hereinafter sometimes referred to as a "fluorene-derived structural unit"), a structural unit derived from a compound having a siloxane bond and a polymerizable unsaturated bond (hereinafter sometimes referred to as a "siloxane-derived structural unit"), a structural unit derived from a (meth)acrylic acid alkyl ester (hereinafter sometimes referred to as a "(meth)acrylic acid-derived structural unit"), and a structural unit derived from a reversible addition-fragmentation chain transfer agent (Reversible Addition Fragmentation Chain Transfer Polymerization, sometimes abbreviated as "RAFT agent" in this specification) (hereinafter sometimes referred to as a "RAFT agent-derived structural unit").

[0027] The resin for the substrate preferably contains, as structural units derived from monomers, one or both of the urethane-derived structural unit and the fluorene-derived structural unit, one or both of the siloxane-derived structural unit and the (meth)acrylic acid-derived structural unit, and the RAFT agent-derived structural unit. The reason is that it is easy to obtain a stretchable resin substrate 11 with good stretch durability and a Young's modulus of 30 N / mm ２ or less, and the stretchability hardly deteriorates even when repeatedly stretched and contracted.

[0028] Among the structural units derived from monomers of the resin for the substrate, the proportions of the urethane-derived structural unit, the fluorene-derived structural unit, the siloxane-derived structural unit, the (meth)acrylic acid-derived structural unit, and the RAFT agent-derived structural unit are not particularly limited and can be appropriately determined according to the use of the stretchable resin substrate 11, the required strength, elongation at break, stretch durability, and other properties.

[0029] The more urethane bonds there are in the base resin, the lower the Young's modulus and the easier it is to obtain a resin wiring board 10 with excellent flexibility. For this reason, it is preferable that the base resin contains urethane-derived structural units. When the base resin contains urethane-derived structural units as structural units derived from monomers, the proportion of urethane-derived structural units among the monomer-derived structural units in the base resin is preferably 1% to 80% by mass, and more preferably 5% to 50% by mass. This is because if the proportion of urethane-derived structural units is 1% by mass or more, the effects of including urethane-derived structural units can be fully obtained. Furthermore, if the proportion of urethane-derived structural units is 80% by mass or less, it is possible to sufficiently include structural units other than urethane-derived structural units, making it easier to obtain a stretchable resin base material 11 with good stretch durability that does not deteriorate easily even when repeatedly stretched and contracted.

[0030] The greater the number of fluorene-derived structural units in the base resin, the more likely it is to result in a stretchable resin base material 11 with excellent flexibility and good durability. When the base resin contains fluorene-derived structural units as monomer-derived structural units, the proportion of fluorene-derived structural units among the monomer-derived structural units in the base resin is preferably 30% to 99% by mass, and more preferably 35% to 90% by mass. This is because if the proportion of fluorene-derived structural units is 30% by mass or more, the effects of including fluorene-derived structural units can be fully obtained. Furthermore, if the proportion of fluorene-derived structural units is 99% by mass or less, it is possible to sufficiently include structural units other than fluorene-derived structural units, making it easier to obtain a stretchable resin base material 11 with a lower Young's modulus.

[0031] When the resin used as the base material has siloxane-derived structural units, the stretchable resin base material 11 will have appropriate water repellency. As a result, the stretchable resin base material 11 will have excellent durability with suppressed deterioration over time caused by moisture. Furthermore, when the resin used as the base material has siloxane-derived structural units, the stretchable resin base material 11 will have good tackiness (adhesion), and the resin wiring board 10 will be less prone to delamination between the stretchable resin base material 11 and the resin coating layer 31.

[0032] When the resin for the base material contains siloxane-derived structural units as structural units derived from monomers, the ratio of siloxane-derived structural units to 100 parts by mass of the first oligomer, which is obtained by polymerizing one or more monomers selected from urethane-derived structural units, fluorene-derived structural units, and (meth)acrylic acid-derived structural units by a known method, is preferably 0.5 to 10 parts by mass, and more preferably 1% to 5% by mass. When the ratio of siloxane-derived structural units is 0.5 parts by mass or more, the effects of including siloxane-derived structural units are sufficiently obtained. Furthermore, when the ratio of siloxane-derived structural units is 10 parts by mass or less, structural units other than siloxane-derived structural units can be sufficiently included, making it easier to obtain an expandable resin base material 11 with properties appropriate to the application.

[0033] When the base resin contains both urethane-derived structural units and siloxane-derived structural units, it is preferable because the urethane bonds in the stretchable resin base material 11 are less susceptible to hydrolysis, resulting in a stretchable resin base material 11 with suppressed deterioration over time due to hydrolysis. When the base resin contains both urethane-derived structural units and siloxane-derived structural units, the greater the number of siloxane bonds in the stretchable resin base material 11, the less susceptible the urethane bonds in the stretchable resin base material 11 are to hydrolysis, resulting in a resin wiring board 10 with excellent durability. When the base resin contains both urethane-derived structural units and siloxane-derived structural units, the ratio of the number of urethane bonds to the number of siloxane bonds in the base resin is not particularly limited and can be appropriately determined according to the application of the resin wiring board 10, the required stretch durability, and the characteristics such as elongation at break.

[0034] When the base resin contains (meth)acrylic acid-derived structural units, the greater the number of (meth)acrylic acid-derived structural units, the higher the Young's modulus and the more durable the stretchable resin base material 11 becomes, with good stretchability that does not deteriorate easily even after repeated stretching. When the base resin contains (meth)acrylic acid-derived structural units as structural units derived from monomers, the proportion of (meth)acrylic acid-derived structural units among the monomer-derived structural units in the base resin is preferably 21% to 44% by mass. This is because if the proportion of (meth)acrylic acid-derived structural units is 21% by mass or more, the effect of improving stretchability due to the inclusion of (meth)acrylic acid-derived structural units is sufficiently obtained. Furthermore, if the proportion of (meth)acrylic acid-derived structural units is 44% or less, the Young's modulus becomes 30 N / mm² due to the inclusion of structural units other than (meth)acrylic acid-derived structural units. ２ This is because the following stretchable resin base material 11 is easily obtained.

[0035] When the base resin contains structural units derived from the RAFT agent, variations in the degree of polymerization and crosslinking state are suppressed, resulting in a base resin that is easily dispersed or dissolved in a solvent. When the base resin contains structural units derived from the RAFT agent as monomer-derived structural units, it is preferable that the amount is 0.2 to 5 parts by mass per 100 parts by mass of the total monomers contained in the base resin. This is because if the amount of RAFT agent-derived structural units is 0.2 parts by mass or more per 100 parts by mass of the total monomers contained in the base resin, the effects of containing RAFT agent-derived structural units can be fully obtained. Furthermore, if the amount of RAFT agent-derived structural units is 5 parts by mass or less per 100 parts by mass of the total monomers contained in the base resin, it is possible to sufficiently contain structural units other than RAFT agent-derived structural units, making it easier to obtain an expandable resin base material 11 with properties appropriate to the application.

[0036] The base resin can be produced, for example, by the method shown below. First, one or more monomers selected from a compound having urethane bonds and polymerizable unsaturated bonds, a compound having a fluorene skeleton, and alkyl (meth)acrylate esters are polymerized by a known method to produce a first oligomer. Next, a compound having siloxane bonds and polymerizable unsaturated bonds is polymerized by a known method to produce a second oligomer. Subsequently, the first oligomer, the second oligomer, a polymerization initiator, and a RAFT agent are used to produce a base resin by reversible addition-fraction chain transfer polymerization (RAFT polymerization) under known conditions. This production method is preferable because it makes it easy to obtain a base resin having a skeleton made of a polymer of the first oligomer and short-chain branching containing structural units derived from a compound having siloxane bonds and polymerizable unsaturated bonds.

[0037] The resin for the base material may be produced by a method of reversible addition-fraction chain transfer polymerization (RAFT polymerization) under known conditions using a compound having urethane bonds and polymerizable unsaturated bonds, a compound having a fluorene skeleton, an alkyl (meth)acrylate ester, a compound having siloxane bonds and polymerizable unsaturated bonds, a polymerization initiator, and a RAFT agent.

[0038] Examples of compounds having urethane bonds and polymerizable unsaturated bonds that can be used as monomers when manufacturing resins for base materials include known compounds (urethane (meth)acrylates) that have urethane bonds and a (meth)acryloyl group as a polymerizable unsaturated bond group. Only one type of compound having urethane bonds and polymerizable unsaturated bonds may be used, or two or more types may be used.

[0039] The compound having a urethane bond and a polymerizable unsaturated bond used in the manufacture of the base material may be an oligomer having a urethane bond and a polymerizable unsaturated bond. Specific examples of oligomers having a urethane bond and a polymerizable unsaturated bond include acrylic urethane, polyether urethane, carbonate urethane, polyester urethane, and aromatic urethane. As the oligomer having a urethane bond and a polymerizable unsaturated bond, it is preferable to use acrylic urethane because it results in a highly flexible and stretchable resin base material 11. It is even more preferable to use an oligomer having a structural unit having a urethane bond and a (meth)acryloyl group, and a structural unit having a urethane bond but not a (meth)acryloyl group. In particular, it is preferable to use the compound represented by the following formula (1).

[0040]

[0041] As an oligomer having urethane bonds and polymerizable unsaturated bonds, it is also preferable to use an acrylic urethane represented by the following formula (12) because it results in a resin substrate 11 with good flexibility.

[0042] (n in equation (12)) １ R indicates the degree of polymerization, ranging from 1 to 40. １１ R is a methylene chain having 1 to 10 carbon atoms, which may be substituted with alkyl groups having 1 to 4 carbon atoms. １２ (This is a divalent group derived from polyols.)

[0043] In equation (12), n １ R indicates the degree of polymerization, which is 1 to 40, and preferably 10 to 20. In formula (12), R １１ R is a methylene chain having 1 to 10 carbon atoms, and may be substituted with an alkyl group having 1 to 4 carbon atoms. １１ It is preferable that the R is a methylene chain having 1 to 8 carbon atoms, which may be substituted with an alkyl group having 1 to 3 carbon atoms. １１ Specifically, for example, -(CH ２ ) ２ -, - (CH ２ )​３ -, - (CH ２ ) ４ -, - (CH ２ ) ６ -ien-CH ２ CH (CH ２ CH ３ )-(CH ２ ) ４ - are some examples. Multiple R's included in equation (12) １１ They may all be different, or some or all of them may be the same, but it is preferable that they all be the same because it is easier to manufacture. In formula (12), R １２ Examples of divalent groups derived from polyols represented by include -(CH ２ )-,-(CH ２ ) ２ -, - (CH ２ ) ３ -, - (CH ２ ) ４ -ien-CH ２ CH (CH ３ )CH ２ -ien-CH ２ CH (CH ２ CH ３ )-(CH ２ ) ４ - are some examples. R １２ R １１ It may be the same as, or it may be different.

[0044] An oligomer having a urethane bond and a polymerizable unsaturated bond is an acrylic urethane represented by formula (12) with acryloyl groups (CH2) located at both ends. ２ =CH ２ Of the C(=O)- groups, one or both are methacryloyl groups (CH ２ =CH(CH ２ It is also preferable to use one that is C(=O)-).

[0045] When using acrylic urethane as the oligomer having urethane bonds and polymerizable unsaturated bonds, it is preferable to use one with a weight-average molecular weight (Mw) of 5,000 to 180,000, and more preferably one with a weight-average molecular weight (Mw) of 5,000 to 150,000. Furthermore, when using acrylic urethane as the oligomer having urethane bonds and polymerizable unsaturated bonds, it is preferable to use one with a number-average molecular weight (Mn) of 3,000 to 150,000, and more preferably one with a number-average molecular weight (Mn) of 3,000 to 120,000, because it can be easily manufactured. This is because a resin substrate 11 with better flexibility is more easily obtained when the weight-average molecular weight (Mw) of the oligomer having urethane bonds and polymerizable unsaturated bonds is 5,000 or more and / or the number-average molecular weight (Mn) is 3,000 or more. In addition, when the weight-average molecular weight (Mw) is 180,000 or less and / or the number-average molecular weight (Mn) is 150,000 or less, it is possible to prevent the resin component from gelling during polymerization for manufacturing the resin for the substrate.

[0046] As oligomers having urethane bonds and polymerizable unsaturated bonds, for example, a polyether-based urethane represented by the following formula (13) and / or a polyester-based urethane represented by the following formula (14) may be used.

[0047] (n in equation (13)) ２ indicates the degree of polymerization, ranging from 1 to 50. m indicates the degree of polymerization, ranging from 5 to 20. R １３ R is a divalent organic group having 1 to 10 carbon atoms and possessing polymerizable unsaturated bonds. １４ and R １５ R is a monovalent terminal group, and may be the same or different.) (R in formula (14) １６ and R １７ R is a monovalent terminal group, and may be the same or different. １８ It is a divalent organic group having 1 to 10 carbon atoms and possessing polymerizable unsaturated bonds. １９ These are divalent organic groups having 1 to 10 carbon atoms and possessing polymerizable unsaturated bonds; they may be the same or different.

[0048] In equation (13), n ２ represents the degree of polymerization, which is 1 to 50, and preferably 10 to 40. In formula (13), m represents the degree of polymerization, which is 5 to 20, and preferably 10 to 20.

[0049] In equation (13), R １３ R is a divalent organic group having 1 to 10 carbon atoms and possessing polymerizable unsaturated bonds. １３ The group having a polymerizable unsaturated bond preferably has a group containing an ethylenically unsaturated bond, such as an acryloyl group (CH ２ =CH ２ C(=O)-) and / or methacryloyl group (CH ２ =CH(CH ２ It is preferable that it is a divalent organic group having 1 to 10 carbon atoms and containing )C(=O)-). １３ The structure, along with the acryloyl group and / or methacryloyl group, is derived from an epoxy group, and one or more methylene groups (-CH ２ It is preferable that the structure or group includes one of the following: a methylene chain having -), a carbonyl group (>C=O), or a carbonate group (-O-(C=O)-O-).

[0050] In equation (13), R １４ and R １５ R is a monovalent terminal group, and may be the same or different. １４ and R １５ Each of these is preferably a terminal group selected from the group consisting of a hydrogen atom, a hydroxyl group, a carboxyl group, an aldehyde group, and an amide group. １４ It is preferable that R is -OH or -COOH. １５ R １３ R １５ If the structure connected to is not a methylene group, -CH ２ OH or -CH ２ It is preferable that it be COOH.

[0051] In equation (14), R １６ and R １７is a monovalent terminal group, which may be the same or different from each other. R １６ and R １７ are each preferably any terminal group selected from the group consisting of a hydrogen atom, a hydroxyl group, a carboxyl group, an aldehyde group, and an amide group. R １６ and R １７ are each preferably any one selected from -OH, -COOH, -CH ２ OH, -CH ２ COOH, -C(=O)CH ３ .

[0052] In formula (14), R １８ is a divalent organic group having 1 to 10 carbon atoms with a polymerizable unsaturated bond. R １８ is preferably a group having an ethylenically unsaturated bond as a group having a polymerizable unsaturated bond, and an acryloyl group (CH ２ =CH ２ C(=O)-) and / or a methacryloyl group (CH ２ =CH(CH ２ ))C(=O)-) and is preferably a divalent organic group having 1 to 10 carbon atoms. R １８ is preferably one containing a structure derived from an epoxy group, a methylene chain having one or more methylene groups (-CH ２ -), a carbonyl group (>C=O), or a carbonate group (-O-(C=O)-O-) together with an acryloyl group and / or a methacryloyl group.

[0053] The oligomer having a urethane bond and a polymerizable unsaturated bond may be any of a random copolymer, a block copolymer, and an alternating copolymer, and since it can be easily produced, it is preferably a random copolymer.

[0054] Compounds having a fluorene skeleton (9,9-bisphenylfluorene skeleton) used as monomers when manufacturing base resins can include fluorene compounds that have a fluorene skeleton and reactive groups such as hydroxyl groups and amino groups. Specific examples of compounds having a fluorene skeleton include bisphenol fluorene (BPF), biscresol fluorene (BCF), bisaminophenyl fluorene (BAFL), and bisphenoxyethanol fluorene (BPEF). Only one type of compound having a fluorene skeleton may be used, or two or more types may be used.

[0055] Examples of alkyl (meth)acrylate esters used as monomers when manufacturing resins for base materials include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, sec-butyl (meth)acrylate, tert-butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, n-octyl (meth)acrylate, n-nonyl (meth)acrylate, isononyl (meth)acrylate, and decyl (meth)acrylate. Only one type of alkyl (meth)acrylate ester may be used, or two or more types may be used. The alkyl methacrylate is preferably methyl (meth)acrylate because it has good dispersibility with compounds having urethane bonds and polymerizable unsaturated bonds that are used as monomers when manufacturing resins for base materials.

[0056] Examples of compounds having siloxane bonds and polymerizable unsaturated bonds that can be used as monomers when manufacturing resins for base materials include various known silicone resins having a (meth)acryloyl group as the group having a polymerizable unsaturated bond. Only one type of compound having siloxane bonds and polymerizable unsaturated bonds may be used, or two or more types may be used.

[0057] Compounds having siloxane bonds and polymerizable unsaturated bonds may be oligomers obtained by polymerizing compounds having siloxane bonds and polymerizable unsaturated bonds. Examples of such oligomers include those having structural units derived from modified polydialkylsiloxanes in which (meth)acryloyl groups are bonded to one or both ends of a polydialkylsiloxane such as polydimethylsiloxane. Preferably, the above oligomer has structural units derived from modified polydialkylsiloxanes in which (meth)acryloyl groups are bonded to one end of a polydialkylsiloxane. This is because it is possible to produce a resin substrate 11 that consists of a short-chain branched substrate resin containing siloxane-derived structural units, and that fully obtains the effects of containing siloxane-derived structural units. As an oligomer obtained by polymerizing a compound having a siloxane bond and a polymerizable unsaturated bond, it is particularly preferable to use the compound represented by the following formula (2) (Sylabrene® FM-0721; trade name, manufactured by JNC Corporation) which has structural units derived from modified polydimethylsiloxane.

[0058] (In formula (2), n represents the degree of polymerization and ranges from 10 to 150. Me is -CH ３ Therefore, n-Bu is -CH ２ CH ２ CH ２ CH ３ (That is the case.)

[0059] As the RAFT agent, it is preferable to use one or more groups represented by the following general formulas (11), (21), or (31).

[0060] (In formula (11), Z1 is an alkyl group, and one or more hydrogen atoms in the alkyl group may be substituted with a cyano group, a carboxyl group, a methoxycarbonyl group, or an aryl group, and the two or more substituents may be the same or different from each other. In formula (21), Z2 is an alkyl group, and Z3 is an aryl group. In formula (31), R4 is a hydrogen atom or a halogen atom. The asterisk (*) in formulas (11), (21), or (31) indicates a bond that the group represented by formula (11), (21), or (31) is bonded to.)

[0061] When manufacturing resins for base materials, one or more known polymerization initiators can be used, such as persulfates, hydrogen peroxide, azo compounds, and organic peroxides. It is preferable to use an azo compound such as dimethyl-2,2'-azobis(2-methylpropionate).

[0062] In the above method for producing the base resin, the first oligomer and the second oligomer are polymerized using a RAFT agent, so that a cross-linked structure is formed during polymerization, thereby preventing the resin component from gelling. Furthermore, in the above method, since the first oligomer and the second oligomer are polymerized using RAFT, a base resin with the desired degree of polymerization and cross-linked state can be easily produced.

[0063] Furthermore, if the base resin does not have siloxane-derived structural units, the base resin can be produced, for example, by the method shown below. That is, it can be produced by reversible addition-fraction chain transfer polymerization (RAFT polymerization) under known conditions using a polymerization initiator and a RAFT agent, with one or more monomers selected from compounds having urethane bonds and polymerizable unsaturated bonds, compounds having a fluorene skeleton, and alkyl (meth)acrylate esters. In this case, since one or more monomers are polymerized using a RAFT agent, the formation of a crosslinked structure during polymerization can prevent the resin components from gelling. In addition, in the above production method, since one or more monomers are polymerized using a RAFT agent, a base resin with the desired degree of polymerization and crosslinked state can be easily produced.

[0064] "Filler" Fillers that may be included in the stretchable resin substrate 11 as needed include, for example, carbon black, silica, calcium carbonate, talc, clay, etc. Only one type of filler may be used, or two or more types may be used. The type and shape of the filler, such as particle size, are not particularly limited and can be appropriately determined according to the application of the stretchable resin substrate 11 and the required strength, elongation at break, stretch durability, and other characteristics.

[0065] When the stretchable resin base material 11 contains a filler, the filler content in the stretchable resin base material 11 is preferably 5 to 30 parts by mass, and more preferably 10 to 20 parts by mass, per 100 parts by mass of the base material resin. If the filler content in the stretchable resin base material 11 is 5 parts by mass or more per 100 parts by mass of the base material resin, the effect of improving stretchability due to the inclusion of the filler can be sufficiently obtained. Furthermore, if the filler content in the stretchable resin base material 11 is 30 parts by mass or less per 100 parts by mass of the base material resin, it is possible to prevent the filler content from being too high and impairing the flexibility of the stretchable resin base material 11.

[0066] The stretchable resin substrate 11 is preferably obtained by solidifying a resin composition containing a base resin, a filler as needed, and a solvent. The solvent contained in the resin composition can be any solvent that can disperse or dissolve the base resin. Specifically, as the solvent, you can use N,N-dimethylacetamide (DMAc), methyl ethyl ketone (MEK), N,N-dimethylformamide (DMF), diethylene glycol monobutyl ether, diethylene glycol monobutyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol monomethyl ether acetate, butyl carbitol (BC), butyl carbitol acetate (BCA) ethyl cyanoacrylate (ECA), α-terpineol, acetone, ethanol, methanol, ethyl lactate, butyl lactate, toluene, isopropyl alcohol, isobutyl alcohol, ethyl acetate, butyl acetate, etc. As the solvent, you may use only one of the above solvents or two or more. As a solvent, it is preferable to use methyl ethyl ketone (MEK) and / or butyl carbitol acetate (BCA) because the resin for the base material disperses or dissolves easily.

[0067] The stretchable resin substrate 11 has a breaking elongation of 200% or more. Preferably, the stretchable resin substrate 11 has a breaking elongation of 260% or more, and more preferably, 450% or more. When the stretchable resin substrate 11 has a breaking elongation of 200% or more, it becomes a resin wiring board 10 that can be suitably used in various highly flexible stretchable devices such as wearable devices. The breaking elongation of the stretchable resin substrate 11 can be changed by appropriately selecting the material and amount used for the stretchable resin substrate 11. Furthermore, it is preferable that the breaking elongation of the stretchable resin substrate 11 be 3000% or less. This is because it is easier to obtain a stretchable resin substrate 11 with good stretch durability that does not deteriorate easily even when repeatedly stretched and contracted.

[0068] In this specification, "elongation at break" is defined as {(length at break - length before stretching) / length before stretching} × 100 (%). Elongation at break can be measured for each predetermined direction. In this specification, for example, "elongation at break of the stretchable resin substrate 11 is 200% or more" means that the elongation at break in the direction with the maximum elongation at break is 200% or more. If there is no anisotropy in the elongation at break, the elongation at break will be the same in all directions. Also, if the anisotropy of the elongation at break is small, the elongation at break will be close in all directions.

[0069] (Metal foil wiring pattern) The metal foil wiring pattern 21 consists of a copper material with copper as the main component. "Copper material with copper as the main component" means that the copper material contains more than 50 wt% copper. The copper alloy powder with copper as the main component preferably contains 70 wt% or more copper, more preferably 80 wt% or more copper, and even more preferably 90 wt% or more copper.

[0070] The metal foil wiring pattern 21 is linear in shape with a uniform width in plan view. The planar shape of the metal foil wiring pattern 21 is not particularly limited and can be appropriately determined according to the application of the resin wiring substrate 10. Preferably, the planar shape of the metal foil wiring pattern 21 is such that it is difficult for the wires to break and peel off even if the stretchable resin substrate 11 is deformed. For example, it can be a curved shape in which continuous arcs with a predetermined radius of curvature are connected. The number of metal foil wiring patterns 21 can also be appropriately determined according to the application of the resin wiring substrate 10.

[0071] The thickness of the metal foil wiring pattern 21 is preferably 2 μm to 50 μm. The lower limit of the thickness of the metal foil wiring pattern 21 may be 3 μm, 4 μm, or 5 μm. The upper limit of the thickness of the metal foil wiring pattern 21 may be 45 μm, 40 μm, 30 μm, 25 μm, 20 μm, 15 μm, or 10 μm.

[0072] (Position of metal foil wiring pattern) Figure 3A is a schematic cross-sectional view showing the resin wiring substrate in a bent state, and Figure 3B is a schematic cross-sectional view of the resin wiring substrate 10 to indicate the position of the metal foil wiring pattern. In Figure 3B, reference numeral t denotes Ｔ is the thickness of the stretchable resin substrate 11 (substantially the same as the thickness of the resin wiring board 10), and the symbol t d t is the distance from the lower surface of the resin wiring substrate 10 to the position of the metal foil wiring pattern, and is denoted by t. d This is the distance from the top surface of the resin wiring board 10 to the position of the metal foil wiring pattern.

[0073] The metal foil wiring pattern 21 extends from the surface facing inward in the bending direction of the resin wiring substrate 10 to the total substrate thickness t Ｔ It is preferable that the metal foil wiring pattern 21 is located in the range of 5% to 50% of the area. That is, the metal foil wiring pattern 21 is located in the area t indicated by the dotted arrow within the resin wiring substrate 10 shown in Figure 3. Ｐ It is preferable to position the metal foil wiring pattern 21 within the range of the resin wiring substrate 10. Ｔ The range can be 5% to 45%, 5% to 40%, 5% to 30%, 10% to 45%, 10% to 40%, or 10% to 30%.

[0074] The metal foil wiring pattern 21 is affected by the stress of the stretchable resin substrate 11 on its upper and lower surfaces. When the stretchable resin substrate 11 bends, tensile stress is generated outside the center in the thickness direction, and compressive stress is generated inside the center in the thickness direction. When the resin wiring board 10 is bent, the metal foil wiring pattern 21 is subjected to tensile or compressive stress from the stretchable resin substrate 11 depending on its position within the resin wiring board 10. Although the stress from the resin wiring board 10 is smallest when the metal foil wiring pattern 21 is placed at the center in the thickness direction of the resin wiring board 10, there are cases where it is desirable to place the metal foil wiring pattern 21 closer to the inner part of the bend in the thickness direction of the resin wiring board 10 (indicated as Sin in Figure 3A) for reasons other than the stress received from the resin wiring board 10, such as the fact that the outer part of the bend in the thickness direction of the resin wiring board 10 (indicated as Sout in Figure 3A) is expected to be subjected to external forces during use.

[0075] Simulations using the Young's modulus and Poisson's ratio of the material as parameters revealed that the metal foil wiring pattern 21 receives less stress from the stretchable resin substrate 11 when it is placed in the outer part of the thickness direction (indicated as Sin in Figure 3A) than when it is placed in the outer part (indicated as Sout in Figure 3A).

[0076] (Electronic Components) In the stretchable device of this embodiment, two electronic components 41 are arranged on the surface 11Aa of the stretchable resin substrate 11 of the resin wiring board 10. These electronic components 41 are electrically connected to the metal foil wiring patterns 21 shown in Figures 2(a) and 2(b). The number and type of electronic components 41 are not particularly limited and are appropriately determined according to the application of the stretchable device.

[0077] As the electronic component 41, any known electronic component can be used. Examples of electronic components 41 include various sensors, capacitors, inductors, high-frequency filters, transformers, resistors, varistors, diodes, various ICs, various actuators, antennas, and batteries. When the electronic component 41 is a battery, examples include solar cells, lithium-ion batteries, and electric double-layer capacitors. As for solar cells, from the viewpoint of electrode arrangement, double-sided electrode solar cells and back-side electrode solar cells can be mentioned. Furthermore, from the viewpoint of materials, examples include silicon-based solar cells, inorganic material solar cells such as compound semiconductor solar cells, and organic solar cells.

[0078] [Method for Manufacturing a Resin Wiring Board] (Formation of a Stretchable Resin Substrate 11A) First, a resin composition containing the above-mentioned substrate resin, a filler as needed, and a solvent is prepared using a known method. Next, the resin composition is applied to a manufacturing substrate (not shown) with a predetermined planar shape and thickness to form a resin composition layer having a strip-like shape corresponding to the planar shape of the stretchable resin substrate 11 (coating step). In the coating step, a known method can be used to apply the resin composition. Specifically, as a coating method, for example, a method using various coaters or wire bars, or various printing methods including inkjet printing can be used.

[0079] Next, the resin composition layer is dried and solidified (drying and solidification step). This yields a sheet-like stretchable resin substrate 11A as shown in Figure 4(a). In the drying and solidification step, the drying temperature for drying the resin composition layer is preferably 25°C to 150°C, and more preferably 25°C to 120°C. A drying temperature of 25°C or higher allows the resin composition layer to be dried more efficiently, enabling the efficient production of the sheet-like stretchable resin substrate 11A. A drying temperature of 150°C or lower suppresses deterioration of the sheet-like stretchable resin substrate 11A due to excessively high drying temperatures.

[0080] In the drying and solidification process, the completion of solidification can be confirmed, for example, by the fact that no clear change in the mass of the resin composition layer being dried is observed. Next, in this embodiment, the sheet-like stretchable resin substrate 11A is peeled off from the manufacturing substrate.

[0081] (Arrangement of metal foil wiring pattern) Next, as shown in Figure 4(b), the pre-prepared metal foil wiring pattern 21 is placed on one surface 11Aa of the stretchable resin substrate 11A. The metal foil wiring pattern 21 can be manufactured by known methods. For example, a copper sheet formed into a predetermined wiring pattern from copper deposited on the cathode by electrolysis, or a copper sheet formed into a predetermined wiring pattern from a copper sheet obtained by rolling from an ingot by rolling can be used. Alternatively, a commercially available copper foil tape formed into a predetermined wiring pattern can be used.

[0082] The metal foil wiring pattern 21 may be bonded to one surface 11Aa of the stretchable resin substrate 11A using a known stretchable conductive adhesive. The stretchable conductive adhesive comprises a stretchable resin and a conductive filler. The stretchable resin is not particularly limited, and any known stretchable resin can be used. Examples include epoxy resins, urethane resins, urea resins, polyurethane urea resins, methacrylic acid resins, polyacrylic resins, silicone resins, diene resins, polyester resins, polyether resins, polyamide resins, polystyrene resins, and polyimide resins. The conductive filler is not particularly limited, and any known conductive filler can be used. Examples include silver (Ag) powder, carbon (C), copper (Cu) powder, palladium (Pd) powder, gold (Au) powder, and platinum (Pt) powder. Among these, silver powder is preferred because it has low resistance and is less prone to oxidation.

[0083] (Formation of stretchable resin substrate 11B) Next, in the same manner as in the formation of the stretchable resin substrate 11A, the stretchable resin substrate 11B is formed on the first surface 11Aa of the stretchable resin substrate 11A having a metal foil wiring pattern 21 using a resin composition containing the above-described substrate resin and solvent.

[0084] First, the resin composition containing the above-mentioned base material resin and solvent is applied to the first surface 11Aa of the stretchable resin base material 11A having a metal foil wiring pattern 21 in a shape corresponding to the planar shape of the resin composition layer, thereby forming a resin composition layer of a predetermined thickness (coating step). It is preferable to apply the resin composition to the first surface 11a of the stretchable resin base material 11A while heating the stretchable resin base material 11A having a metal foil wiring pattern 21. In the coating step, the method for applying the resin composition can be the same as the method used when forming the stretchable resin base material 11A.

[0085] Next, the resin composition layer is dried and solidified in the same manner as when forming the stretchable resin substrate 11A (drying and solidification step). This forms the stretchable resin substrate 11B that covers the metal foil wiring pattern 21. In the drying and solidification step, the drying temperature for drying the resin composition layer is preferably, for example, 25°C to 150°C, and more preferably 25°C to 120°C, similar to when forming the stretchable resin substrate 11A. If the drying temperature is 25°C or higher, the resin composition layer can be dried more efficiently, and the stretchable resin substrate 11A can be manufactured efficiently. If the drying temperature is 150°C or lower, it is possible to suppress deterioration of the stretchable resin substrate 11 having the metal foil wiring pattern 21 due to an excessively high drying temperature.

[0086] [Manufacturing method for stretchable devices] When forming the resin wiring substrate 10 described above, an exposed surface 11Aa of the stretchable resin substrate 11 is provided for mounting electronic components.

[0087] (Mounting of electronic components) Electronic components 41 are placed at predetermined positions on one surface 11Aa of the stretchable resin substrate 11 of the resin wiring board 10 using a known method such as a surface mount machine (mounter). Then, the electronic components 41 and the metal foil wiring pattern 21 are electrically connected using a known method such as molten solder, conductive adhesive, or anisotropic adhesive. By performing the above steps, the stretchable device of this embodiment is obtained.

[0088] [Other Examples] Although embodiments of the present disclosure have been described in detail above, the configurations and combinations thereof in each embodiment are merely examples, and additions, omissions, substitutions, and other modifications of the configurations are possible without departing from the spirit of the present disclosure.

[0089] The contents of this disclosure will be explained in more detail below with reference to examples and comparative examples. This disclosure is not limited to the following examples. [Resin Compositions 1 to 26] A mixed monomer was prepared by mixing the urethane, fluorene, and methacrylic acid shown in Table 1 in the proportions shown in Table 1. A siloxane shown in Table 1 was then mixed in the proportions shown in Table 1 (parts by mass per 100 parts by mass of the mixed monomer). Dimethyl-2,2'-azobis(2-methylpropionate) (V601; trade name, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was added as a polymerization initiator at a rate of 1.0 part by mass per 100 parts by mass of the total monomers, and a RAFT agent (S,S dibenzyltrithiocarbonate; manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was added at a rate of 1.5 parts by mass per 100 parts by mass of the total monomers. Reversible addition-cleavage chain transfer polymerization (RAFT polymerization) was performed by heating in methyl ethyl ketone (MEK) to obtain a resin.

[0090] The obtained resin was mixed with the fillers shown in Table 1 in the proportions shown in Table 1 (parts by mass per 100 parts by mass of resin), and dispersed in MEK as a solvent to prepare resin compositions 1 to 26 having a resin content of 70% to 100% by mass.

[0091]

[0092] The urethane, fluorene, methacrylic acid, siloxane, and fillers A, B, C, and D shown in Table 1 are as follows: [Urethane (resin compositions 1-9, 11-24)] A random copolymer represented by formula (1) (weight-average molecular weight (Mw) 61000, number-average molecular weight (Mn) 30800). [Urethane (resin compositions 25, 26)] A random copolymer represented by formula (12) (n in formula (12) １ It is 20. １１ is, -(CH ２ ) ６ - is R １２ is, -(CH ２) - The weight-average molecular weight (Mw) is 5200, and the number-average molecular weight (Mn) is 4110.

[0093] [Fluorene] GA-2800 (trade name; manufactured by Osaka Gas Chemical Co., Ltd.). [Methacrylic acid] Methyl methacrylate (manufactured by Kuraray Co., Ltd.). [Siloxane] A compound represented by formula (2) having structural units derived from modified polydimethylsiloxane (Sirabrain® FM-0721; trade name; manufactured by JNC Co., Ltd.). [A] Silica, average particle size 2.1 μm to 2.6 μm (manufactured by Tosoh Silica Co., Ltd.). [B] Silica, average particle size 1.5 μm to 1.9 μm (manufactured by Tosoh Silica Co., Ltd.). [C] Calcium carbonate, average particle size: 0.7 μm (manufactured by Shiraishi Calcium Co., Ltd.). [D] Silica, average particle size: 2.5 μm to 3.5 μm (manufactured by Tosoh Silica Co., Ltd.).

[0094] Using the resin compositions 1 to 26 obtained in this manner, stretchable resin substrates 1 to 26 were formed by the following method. Resin compositions 1 to 26 were each applied to a manufacturing substrate made of PET film using a coater, and dried and solidified at 80°C to obtain sheet-like stretchable resin substrates 1 to 26 with a thickness of 0.05 mm.

[0095] The stretchable resin substrates 1 to 26 obtained in this manner were peeled off the manufacturing substrate, and their Young's modulus, elongation at break, strength, and stretch durability were examined using the method described below. The results are shown in Table 2. In the method described below, the Young's modulus, elongation at break, strength, and stretch durability of the resin substrate were measured at a measurement point with a width of 10 mm and a length of 10 mm. However, the measurement results for the Young's modulus, elongation at break, strength, and stretch durability of the resin substrate were similar regardless of the dimensions of the measurement point. Therefore, the dimensions of the measurement point for the above items on the resin substrate may be, for example, 5 mm wide and 5 mm long, or 3 mm wide and 3 mm long.

[0096] [Measurement of Young's Modulus] Five strip-shaped measurement samples, each 10 mm wide and 35 mm long, were cut from the stretchable resin substrate. A metal substrate was placed between the grips above and below the measuring instrument, and the measurement samples were fixed to the metal substrate with double-sided tape so that the measurement area was 10 mm wide and 10 mm long. Then, the tensile stress and strain of the measurement samples were measured using a tensile testing machine (product name: Autograph AGS-5kNX, manufactured by Shimadzu Corporation). A stress-strain diagram was created using the results, and the Young's modulus of the measurement samples was calculated from the slope of the proportional limit. The average of the Young's moduli of the five measurement samples was then taken as the Young's modulus of each stretchable resin substrate.

[0097] [Strength Measurement] Five strip-shaped measurement samples, each 10 mm wide and 35 mm long, were cut from a stretchable resin substrate. For each measurement sample, the maximum tensile strength was calculated using the method described below, and the average value was taken as the strength. A metal substrate was placed between the grips above and below the measuring instrument, and the measurement sample was fixed to the metal substrate with double-sided tape so that the measurement area was 10 mm wide and 10 mm long. Then, the measurement sample was pulled at a tensile speed of 10 mm / min using a tensile testing machine (product name: Autograph AGS-5kNX, manufactured by Shimadzu Corporation). The maximum tensile strength of the measurement sample was then measured.

[0098] [Measurement of Elongation at Break] Six strip-shaped measurement samples, each 10 mm wide and 30 mm long, were cut from the stretchable resin substrate. For each measurement sample, the elongation at break was calculated using the method described below.

[0099] A metal substrate was clamped between the grips above and below the measuring instrument, and the measurement sample was fixed to the metal substrate with double-sided tape so that the measurement area was 10 mm wide and 10 mm long. Then, the measurement sample was pulled at a tensile speed of 10 mm / min using a tensile testing machine (product name: Autograph AGS-5kNX, manufactured by Shimadzu Corporation). The length of the measurement sample at the time of fracture was measured, and the length before pulling (10 mm) was subtracted from this length to calculate the elongation at fracture (length at fracture - length before pulling) for each measurement sample. The average value was taken as the elongation at fracture, and the fracture elongation rate was calculated using the following formula: Fracture elongation rate (%) = {Elongation at fracture / Length before pulling} × 100

[0100] [Stretch Durability] A strip-shaped measurement sample measuring 10 mm wide and 30 mm long was cut from the stretchable resin substrate in the same manner as the measurement of the elongation at break, and the stretch durability was calculated using the method shown below.

[0101] A metal substrate was placed between the grips above and below the measuring instrument, and the measurement sample was fixed to the metal substrate with double-sided tape so that the measurement area was 10 mm wide and 10 mm long. Then, the measurement sample was pulled at a tensile speed of 10 mm / min using a tensile testing machine (product name: Autograph AGS-5kNX, manufactured by Shimadzu Corporation), and the change in tensile strength when the length was stretched by 2 mm (20% of the length of the measurement area) was measured. Subsequently, the change in tensile strength when the measurement sample was returned to its original length at a tensile speed of 10 mm / min was measured. From these measurement results, the peak strength (maximum value) of the first tensile strength when the measurement sample was stretched and when it was returned to its original length was determined.

[0102] Subsequently, the peak intensity of the stretching strength for the second to 100th stretching tests was determined in the same manner as the peak intensity of the first stretching test. Then, the ratio of the peak intensity of the stretching strength for the first stretching test to the peak intensity of the stretching strength for the 100th stretching test (peak intensity of the stretching strength for the 100th stretching test / peak intensity of the stretching strength for the first stretching test) was calculated to evaluate the stretching durability.

[0103]

[0104] As shown in Tables 1 and 2, by using resin compositions 1-18 and 20-26, a Young's modulus of 30 N / mm² is obtained.２ It was confirmed that the following low-strength stretchable resin substrates 1-18 and 20-26 could be obtained. Furthermore, as shown in stretchable resin substrates 17 and 19, when [urethane] [siloxane] [methacrylic acid] was used as the monomer, it was found that reducing the proportion of [urethane] and increasing the proportion of "methacrylic acid" tended to increase the Young's modulus and improve stretch durability. In addition, as shown in stretchable resin substrates 16 and 20-24, when [urethane] [siloxane] was used as the monomer, it was confirmed that the stretch durability improved by including a filler.

[0105] The stretchable resin substrates 8 and 18 described above were analyzed using high-temperature conversion infrared spectroscopy (O-PTIR) with an infrared spectrometer (product name: mIRage, manufactured by Japan Thermal Consulting Co., Ltd.). The results are shown in Figure 5.

[0106] Figure 5 shows the infrared absorption (IR) spectra of the stretchable resin substrate 8 and the stretchable resin substrate 18. In Figure 5, the dotted line shows the results for the resin substrate 18, and the solid line shows the results for the resin substrate 18.

[0107] The IR spectrum shown in Figure 5 has a wavelength of 1114 cm⁻¹. －１ ±35cm －１ , wavelength 1500cm －１ ±35cm －１ , wavelength 1600cm －１ ±35cm －１ The peak originates from fluorene. Also, the IR spectrum wavelength is 1150 cm. －１ ±35cm －１ The peak originates from methacrylic acid. Also, the IR spectrum wavelength is 1260 cm. －１ ±35cm －１ , wavelength 1741cm －１ ±25cm －１ The peak originates from C=O.

[0108] 10... Resin wiring board, 11... Stretchable resin substrate, 11a... First surface, 21... Metal foil wiring pattern, 100 Stretchable device.

Claims

1. A resin wiring substrate comprising a metal foil wiring pattern made of metal foil mainly composed of copper, and a stretchable resin substrate positioned to sandwich the metal foil wiring pattern from above and below, wherein the stretchable resin substrate has a break elongation rate of 200% or more.

2. The resin wiring substrate according to claim 1, wherein the metal foil wiring pattern is located in a range of 5% to 50% of the total thickness of the substrate from the surface facing inward in the bending direction.

3. The Young's modulus of the stretchable resin substrate is 30 N / mm². ２ The resin wiring board according to claim 1, which is as follows:

4. The resin wiring substrate according to claim 1, wherein the thickness of the metal foil wiring pattern is 50 μm or less, and the thickness of the stretchable resin substrate is 50 μm or more.

5. A stretchable device comprising a resin wiring substrate according to any one of claims 1 to 4.

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