JP7468610B2 - Conductor substrate, wiring substrate, stretchable device, and method for manufacturing wiring substrate - Google Patents

Description

One aspect of the present invention relates to a wiring board that can have high stretchability, and a manufacturing method thereof. Another aspect of the present invention relates to a conductor substrate that can be used to form the wiring board. Yet another aspect of the present invention relates to a stretchable device that uses the wiring board.

In recent years, in fields such as wearable devices and healthcare-related devices, there is a demand for flexibility and stretchability so that devices can be used, for example, along curved surfaces or joints of the body, and are less likely to cause connection problems when put on or taken off. To construct such devices, wiring boards or substrates with high stretchability are required.

Patent Document 1 describes a method for encapsulating semiconductor elements such as memory chips using an elastic resin composition. Patent Document 1 primarily examines the application of the elastic resin composition to encapsulation purposes.

International Publication No. 2016/080346

As described in Patent Document 1, by imparting elasticity to the sealing material, it is possible to realize a member with elasticity that was difficult to achieve with conventional sealing materials. On the other hand, since the base material does not have elasticity, it is difficult to impart higher elasticity to it. Therefore, there is a demand for a wiring board with higher elasticity.

In addition, from the viewpoint of improving heat resistance, the use of crosslinking components having reactive functional groups as materials for producing the base substrate of the wiring board has been considered. However, when crosslinking components having reactive functional groups are used, there is a problem in that the dielectric tangent of the obtained base substrate is likely to increase, and the transmission loss of the wiring provided on the base substrate is likely to increase.

In this situation, one aspect of the present invention aims to provide a conductor substrate having high elasticity and a low dielectric tangent, a wiring substrate using the same, a stretchable device, and a method for manufacturing the wiring substrate.

In order to achieve the above object, one aspect of the present invention provides a conductive substrate having an elastic resin layer and a conductive foil provided on the elastic resin layer, the elastic resin layer including a cured product of a resin composition containing (A) a rubber component, (B) a cross-linking component having an epoxy group, and (C) an ester-based curing agent.

Another aspect of the present invention provides a conductive substrate having an elastic resin layer and a conductive plating film provided on the elastic resin layer, the elastic resin layer including a cured product of a resin composition containing (A) a rubber component, (B) a cross-linking component having an epoxy group, and (C) an ester-based curing agent.

According to the above-mentioned conductor substrate, high elasticity can be obtained by using an elastic resin layer containing a rubber component (A) as the base substrate. In addition, it is considered that the dielectric loss tangent increases when a crosslinking component having a reactive functional group is used as a material for producing an elastic resin layer in the past because the crosslinking component generates hydroxyl groups during the curing reaction. Since hydroxyl groups are functional groups with small volumes and high polarizability, the dielectric loss tangent of the material containing hydroxyl groups increases as a whole. In contrast, the present inventors have found that the generation of hydroxyl groups during the curing reaction of the crosslinking component can be greatly suppressed by using a crosslinking component having an epoxy group (B) as the crosslinking component in combination with an ester-based curing agent (C) as the curing agent. This is because the curing reaction between the epoxy group of the crosslinking component and the ester-based curing agent does not generate hydroxyl groups, and hydroxyl groups are unlikely to be generated even after curing. Furthermore, the cured product does not adversely affect the elasticity. Therefore, according to the conductor substrate having the above configuration, it is possible to achieve a low dielectric loss tangent while maintaining high elasticity and using a crosslinking component that can improve heat resistance.

Another aspect of the present invention provides a wiring board including the conductor substrate of the present invention, in which the conductor foil or conductor plating film forms a wiring pattern. The wiring board is a wiring board in which the conductor foil or conductor plating film in the conductor substrate of the present invention forms a wiring pattern, and is provided with an elastic resin layer having the specific configuration described above. Therefore, the wiring board has high elasticity, and by using a crosslinking component, it has high heat resistance and a low dielectric tangent, and the transmission loss of the wiring pattern is sufficiently reduced.

Another aspect of the present invention provides a stretchable device comprising the wiring board of the present invention and an electronic element mounted on the wiring board. The stretchable device comprises the wiring board of the present invention and an elastic resin layer having the specific configuration described above, and therefore has high elasticity, and by using a crosslinking component, has high heat resistance and a low dielectric tangent, and the transmission loss of the wiring pattern is sufficiently reduced.

Another aspect of the present invention provides the conductor substrate of the present invention, which includes a conductor substrate having an elastic resin layer and a conductor foil or conductor plating film provided on the elastic resin layer, and is used to form a wiring substrate in which the conductor foil or conductor plating film forms a wiring pattern.

Another aspect of the present invention provides a method for producing the wiring board of the present invention, comprising the steps of preparing a laminate having an elastic resin layer and a conductor foil laminated on the elastic resin layer, forming an etching resist on the conductor foil, exposing the etching resist and developing the exposed etching resist to form a resist pattern that covers a portion of the conductor foil, removing the conductor foil from a portion not covered by the resist pattern, and removing the resist pattern.

Another aspect of the present invention provides a method for producing the wiring board of the present invention, comprising the steps of forming a plating resist on an elastic resin layer, exposing the plating resist and developing the exposed plating resist to form a resist pattern that covers a portion of the elastic resin layer, forming a conductor plating film by electroless plating on the surface of the portion of the elastic resin layer that is not covered by the resist pattern, and removing the resist pattern.

Another aspect of the present invention provides a method for producing the wiring board of the present invention, comprising the steps of forming a conductor plating film on an elastic resin layer by electroless plating, forming a plating resist on the conductor plating film, exposing the plating resist and developing the exposed plating resist to form a resist pattern that covers a portion of the elastic resin layer, forming a further conductor plating film by electrolytic plating on the conductor plating film in the portion not covered by the resist pattern, removing the resist pattern, and removing the portion of the conductor plating film formed by electroless plating that is not covered by the conductor plating film formed by electrolytic plating.

Another aspect of the present invention provides a method for producing the wiring board of the present invention, comprising the steps of forming an etching resist on a conductor plating film formed on an elastic resin layer, exposing the etching resist and developing the exposed etching resist to form a resist pattern that covers a portion of the elastic resin layer, removing the conductor plating film from a portion not covered by the resist pattern, and removing the resist pattern.

The above manufacturing method makes it possible to efficiently manufacture the wiring board of the present invention in which the conductor foil or conductor plating film forms the wiring pattern.

According to one aspect of the present invention, it is possible to provide a conductor substrate having high elasticity and a low dielectric tangent, a wiring substrate using the same, a stretchable device, and a method for manufacturing a wiring substrate.

1 is a stress-strain curve showing an example of measuring the recovery rate. FIG. 1 is a plan view showing an embodiment of a wiring board. 1 is a graph showing a temperature profile in a heat resistance test. FIG. 2 is a diagram showing infrared absorption spectra of the stretchable resin layer before and after curing in Comparative Example 1. FIG. 2 is a diagram showing infrared absorption spectra of the stretchable resin layers after curing in Examples 1 and 3 and Comparative Example 1.

Several embodiments of the present invention are described in detail below. However, the present invention is not limited to the following embodiments.

The conductive substrate according to one embodiment has an elastic resin layer and a conductive layer provided on one or both sides of the elastic resin layer, and the elastic resin layer contains a cured product of a resin composition containing (A) a rubber component, (B) a cross-linking component having an epoxy group, and (C) an ester-based curing agent. The wiring substrate according to one embodiment has an elastic resin layer containing a cured product of the resin composition, and a conductive layer provided on one or both sides of the elastic resin layer and forming a wiring pattern. The conductive layer can be a conductive foil or a conductive plating film.

<Conductor substrate>
[Conductor foil]
The elastic modulus of the conductor foil may be 40 to 300 GPa. When the elastic modulus of the conductor foil is 40 to 300 GPa, the conductor foil is less likely to break due to elongation of the wiring board. From the same viewpoint, the elastic modulus of the conductor foil may be 50 GPa or more or 60 GPa or more, and may be 280 GPa or less or 250 GPa or less. The elastic modulus of the conductor foil here may be a value measured by a resonance method.

The conductor foil may be a metal foil. Examples of the metal foil include copper foil, titanium foil, stainless steel foil, nickel foil, permalloy foil, 42 alloy foil, kovar foil, nichrome foil, beryllium copper foil, phosphor bronze foil, brass foil, nickel silver foil, aluminum foil, tin foil, lead foil, zinc foil, solder foil, iron foil, tantalum foil, niobium foil, molybdenum foil, zirconium foil, gold foil, silver foil, palladium foil, Monel foil, Inconel foil, and Hastelloy foil. From the viewpoint of appropriate elastic modulus, the conductor foil may be selected from copper foil, gold foil, nickel foil, and iron foil. From the viewpoint of wiring formability, the conductor foil may be copper foil. Copper foil can be easily formed into a wiring pattern by photolithography without impairing the properties of the elastic resin layer.

The copper foil is not particularly limited, and for example, electrolytic copper foil and rolled copper foil used for copper-clad laminates and flexible wiring boards can be used. Commercially available electrolytic copper foils include, for example, F0-WS-18 (manufactured by Furukawa Electric Co., Ltd., product name), NC-WS-20 (manufactured by Furukawa Electric Co., Ltd., product name), YGP-12 (manufactured by Nippon Denkai Co., Ltd., product name), GTS-18 (manufactured by Furukawa Electric Co., Ltd., product name), and F2-WS-12 (manufactured by Furukawa Electric Co., Ltd., product name). Rolled copper foils include, for example, TPC foil (manufactured by JX Metals Corporation, product name), HA foil (manufactured by JX Metals Corporation, product name), HA-V2 foil (manufactured by JX Metals Corporation, product name), and C1100R (manufactured by Mitsui Sumitomo Metal Mining Co., Ltd., product name). Copper foil that has been subjected to a roughening treatment may be used from the viewpoint of adhesion with the elastic resin layer. Rolled copper foil may be used from the viewpoint of folding resistance.

The metal foil may have a roughened surface formed by a roughening treatment. In this case, the metal foil is usually provided on the stretchable resin layer with the roughened surface facing the stretchable resin layer. From the viewpoint of adhesion between the stretchable resin layer and the metal foil, the surface roughness Ra of the roughened surface may be 0.1 to 3 μm, or 0.2 to 2.0 μm. To easily form fine wiring, the surface roughness Ra of the roughened surface may be 0.3 to 1.5 μm.

The surface roughness Ra can be measured, for example, using a surface profiler Wyko NT9100 (manufactured by Veeco) under the following conditions.
Measurement conditions: Internal lens: 1x External lens: 50x Measurement range: 0.120 x 0.095 mm
Measurement depth: 10 μm
Measurement method: Vertical scanning interferometry (VSI)

The thickness of the conductor foil is not particularly limited, but may be 1 to 50 μm. When the thickness of the conductor foil is 1 μm or more, the wiring pattern can be formed more easily. When the thickness of the conductor foil is 50 μm or less, etching and handling are particularly easy.

The conductor foil is provided on one or both sides of the elastic resin layer. By providing the conductor foil on both sides of the elastic resin layer, warping due to heating for curing, etc. can be suppressed.

The method for providing the conductor foil is not particularly limited, but examples include a method in which the resin composition for forming the elastic resin layer is directly applied to the metal foil, and a method in which the resin composition for forming the elastic resin layer is applied to a carrier film to form a resin layer (elastic resin layer before curing), and the formed resin layer is laminated on the conductor foil.

[Conductor plating film]
The conductor plating film can be formed by a normal plating method used in the additive method or the semi-additive method. For example, after performing a plating catalyst imparting treatment to adhere palladium, the elastic resin layer is immersed in an electroless plating solution to deposit an electroless plating layer (conductor layer) having a thickness of 0.3 to 1.5 μm on the entire surface of the primer. If necessary, electrolytic plating (electrical plating) can be further performed to adjust the required thickness. As the electroless plating solution used for electroless plating, any electroless plating solution can be used, and there is no particular restriction. For electrolytic plating, a normal method can also be adopted, and there is no particular restriction. The conductor plating film (electroless plating film, electrolytic plating film) may be a copper plating film from the viewpoint of cost and resistance value.

The circuit layer can then be formed by etching away unnecessary areas. The etching solution used for etching can be selected appropriately depending on the type of plating. For example, if the conductor is copper plating, the etching solution used for etching can be, for example, a mixed solution of concentrated sulfuric acid and hydrogen peroxide, or a ferric chloride solution.

In order to improve the adhesive strength with the conductor plating film, unevenness may be formed beforehand on the elastic resin layer. One method for forming unevenness is, for example, a method of transferring the roughened surface of copper foil. As the copper foil, for example, YGP-12 (product name, manufactured by Nippon Denkai Co., Ltd.), GTS-18 (product name, manufactured by Furukawa Electric Co., Ltd.), or F2-WS-12 (product name, manufactured by Furukawa Electric Co., Ltd.) can be used.

Methods for transferring the roughened surface of copper foil include, for example, a method in which a resin composition for forming an elastic resin layer is directly applied to the roughened surface of the copper foil, and a method in which the resin composition for forming the elastic resin layer is applied to a carrier film, and then a resin layer (elastic resin layer before curing) is molded onto the copper foil. By forming a conductive plating film on both sides of the elastic resin layer, warping due to heating for curing, etc. can be suppressed.

The elastic resin layer may be subjected to a surface treatment in order to improve adhesion with the conductor plating film. Examples of surface treatments include roughening treatment (desmear treatment), UV treatment, and plasma treatment, which are commonly used in the manufacturing process of wiring boards.

For the desmear process, a method used in the general manufacturing process of wiring boards may be used, for example, an aqueous solution of sodium permanganate may be used.

[Elastic resin layer]
The elastic resin layer can have elasticity such that the recovery rate after tensile deformation to a strain of 20% is 80% or more. This recovery rate is determined in a tensile test using a measurement sample of the elastic resin layer. The strain (displacement) applied in the first tensile test is X, and the difference between the position at which the load begins to be applied when the sample is returned to the initial position and a tensile test is performed again is Y, and R calculated by the formula: R (%) = (Y / X) x 100 is defined as the recovery rate. The recovery rate can be measured with X being 20%. Figure 1 is a stress-strain curve showing an example of the measurement of the recovery rate. From the viewpoint of resistance to repeated use, the recovery rate may be 80% or more, 85% or more, or 90% or more. The upper limit of the recovery rate by definition is 100%.

The elastic modulus (tensile modulus) of the elastic resin layer may be 0.1 MPa or more and 1000 MPa or less. When the elastic modulus is 0.1 MPa or more and 1000 MPa or less, the handleability and flexibility as a substrate tend to be particularly excellent. From this viewpoint, the elastic modulus may be 0.3 MPa or more and 100 MPa or less, or 0.5 MPa or more and 50 MPa or less.

The breaking elongation of the elastic resin layer may be 100% or more. If the breaking elongation is 100% or more, sufficient elasticity tends to be easily obtained. From this viewpoint, the breaking elongation may be 150% or more, 200% or more, 300% or more, or 500% or more. The upper limit of the breaking elongation is not particularly limited, but is usually about 1000% or less.

The dielectric loss tangent (Df) of the elastic resin layer may be 0.004 or less. If the dielectric loss tangent is 0.004 or less, the transmission loss of the wiring pattern provided on the elastic resin layer tends to be sufficiently reduced. From this viewpoint, the dielectric loss tangent may be 0.0035 or less, 0.003 or less, or 0.0025 or less. The lower limit of the dielectric loss tangent is not particularly limited, but is usually about 0.0005 or more.

The dielectric constant (Dk) of the elastic resin layer may be 4.0 or less. If the dielectric constant is 4.0 or less, the transmission loss of the wiring pattern provided on the elastic resin layer tends to be sufficiently reduced. From this viewpoint, the dielectric constant may be 3.5 or less, 3.0 or less, or 2.5 or less.

The elastic resin layer may have no absorption peaks attributable to the stretching vibration of hydroxyl groups in its infrared absorption spectrum. This tends to sufficiently reduce the dielectric tangent of the elastic resin layer, and to sufficiently reduce the transmission loss of the wiring pattern provided on the elastic resin layer.

The elastic resin layer contains a cured product of a resin composition (curable resin composition) containing (A) a rubber component, (B) a cross-linking component having an epoxy group, and (C) an ester-based curing agent. In other words, the elastic resin layer contains a cross-linked polymer of (B) a cross-linking component having an epoxy group. The elastic resin layer is easily given elasticity mainly by the rubber component (A).

The rubber component (A) may contain at least one rubber selected from the group consisting of, for example, acrylic rubber, isoprene rubber, butyl rubber, styrene butadiene rubber, butadiene rubber, acrylonitrile butadiene rubber, silicone rubber, urethane rubber, chloroprene rubber, ethylene propylene rubber, fluororubber, vulcanized rubber, epichlorohydrin rubber, and chlorinated butyl rubber. From the viewpoint of protecting the wiring from damage caused by moisture absorption, etc., a rubber component with low gas permeability may be used. From this viewpoint, the rubber component (A) may contain at least one rubber selected from styrene butadiene rubber, butadiene rubber, and butyl rubber. By using styrene butadiene rubber, the resistance of the elastic resin layer to various chemicals used in the plating process is improved, and wiring boards can be manufactured with a good yield.

Commercially available acrylic rubber products include, for example, Zeon Corporation's "Nipol AR Series" and Kuraray Co., Ltd.'s "Clarity Series."

Commercially available isoprene rubber products include, for example, the "Nipol IR series" from Nippon Zeon Co., Ltd.

Commercially available butyl rubber products include, for example, the "BUTYL series" from JSR Corporation.

Commercially available styrene butadiene rubber products include, for example, JSR Corporation's "Dynaron SEBS series" and "Dynaron HSBR series," Kraton Polymer Japan Ltd.'s "Kraton D Polymer series," and Aronkasei Corporation's "AR series."

Commercially available butadiene rubber products include, for example, the "Nipol BR series" from Nippon Zeon Co., Ltd.

Commercially available acrylonitrile butadiene rubber products include, for example, JSR Corporation's "JSR NBR series."

An example of a commercially available silicone rubber product is the "KMP series" from Shin-Etsu Silicone Co., Ltd.

Commercially available ethylene propylene rubber products include, for example, JSR Corporation's "JSR EP Series."

Commercially available fluororubber products include, for example, Daikin Ltd.'s "Dai-El Series."

Commercially available epichlorohydrin rubber products include, for example, the "Hydrin series" from Zeon Corporation.

The (A) rubber component can also be produced by synthesis. For example, acrylic rubber can be obtained by reacting (meth)acrylic acid, (meth)acrylic acid esters, aromatic vinyl compounds, vinyl cyanide compounds, etc.

The (A) rubber component may contain a rubber having a crosslinking group. The use of a rubber having a crosslinking group tends to improve the heat resistance of the elastic resin layer. The crosslinking group may be a reactive group that can proceed with a reaction that crosslinks the molecular chains of the (A) rubber component. Examples of such a group include the reactive groups of the (B) crosslinking component described below, acid anhydride groups, amino groups, hydroxyl groups, epoxy groups, and carboxyl groups.

The (A) rubber component may contain a rubber having at least one crosslinking group of an acid anhydride group or a carboxyl group. An example of a rubber having an acid anhydride group is a rubber partially modified with maleic anhydride. The rubber partially modified with maleic anhydride is a polymer containing structural units derived from maleic anhydride. An example of a commercially available product of rubber partially modified with maleic anhydride is the styrene-based elastomer "Tufprene 912" manufactured by Asahi Kasei Corporation.

The rubber partially modified with maleic anhydride may be a hydrogenated styrene-based elastomer partially modified with maleic anhydride. Hydrogenated styrene-based elastomers are also expected to have effects such as improved weather resistance. Hydrogenated styrene-based elastomers are elastomers obtained by adding hydrogen to the unsaturated double bonds of a styrene-based elastomer having a soft segment containing an unsaturated double bond. Examples of commercially available hydrogenated styrene-based elastomers partially modified with maleic anhydride include "FG1901" and "FG1924" from Kraton Polymer Japan Co., Ltd., and "Tuftec M1911", "Tuftec M1913", and "Tuftec M1943" from Asahi Kasei Corporation.

The weight average molecular weight of the (A) rubber component may be 20,000 to 200,000, 30,000 to 150,000, or 50,000 to 125,000 from the viewpoint of coating properties. The weight average molecular weight (Mw) here refers to the standard polystyrene equivalent value determined by gel permeation chromatography (GPC).

In the resin composition, the content of the rubber component (A) is preferably 60 to 95% by mass, more preferably 65 to 90% by mass, and even more preferably 70 to 85% by mass, based on the total amount of the rubber component (A), the crosslinking component (B), and the ester-based curing agent (C). When the content of the rubber component (A) is 60% by mass or more, more sufficient elasticity is easily obtained, and the rubber component and the crosslinking component tend to mix well. When the content of the rubber component (A) is 95% by mass or less, the elastic resin layer tends to have particularly excellent properties in terms of adhesion, insulation reliability, and heat resistance. The content of the rubber component (A) in the elastic resin layer may be within the above range based on the mass of the elastic resin layer.

(B) The cross-linking component having an epoxy group is a component that cross-links during a curing reaction to form a cross-linked polymer. (B) The cross-linking component having an epoxy group is not particularly limited as long as it has an epoxy group in the molecule, and can be, for example, a general epoxy resin. The epoxy resin may be monofunctional, bifunctional, or polyfunctional, and is not particularly limited, but a bifunctional or polyfunctional epoxy resin may be used to obtain sufficient curability.

Epoxy resins include bisphenol A type, bisphenol F type, phenol novolac type, naphthalene type, dicyclopentadiene type, cresol novolac type, etc. Epoxy resins modified with aliphatic chains can impart flexibility. An example of a commercially available aliphatic chain modified epoxy resin is EXA-4816 manufactured by DIC Corporation. From the viewpoints of curability, low tackiness, and heat resistance, phenol novolac type, cresol novolac type, naphthalene type, or dicyclopentadiene type epoxy resins may be selected. These epoxy resins can be used alone or in combination of two or more types.

The combination of a rubber having a maleic anhydride group or a carboxyl group with a compound having an epoxy group (epoxy resin) provides particularly excellent effects in terms of the heat resistance and low moisture permeability of the elastic resin layer, adhesion between the elastic resin layer and the conductive layer, and low tack of the elastic resin layer. Improved heat resistance of the elastic resin layer can suppress deterioration of the elastic resin layer during a heating process such as nitrogen reflow. Low tack of the elastic resin layer allows for easy handling of the conductor board or wiring board.

The resin composition may contain other crosslinking components other than the crosslinking component having an epoxy group (B) to the extent that the effect of the present invention is not significantly impaired. From the viewpoint of more sufficiently reducing the dielectric tangent of the elastic resin layer, the content of the other crosslinking components is preferably less than 10 parts by mass per 100 parts by mass of the crosslinking component having an epoxy group (B).

(C) The ester-based curing agent is a compound that itself participates in the curing reaction, and can reduce the dielectric tangent while improving the heat resistance of the elastic resin layer.

The ester-based hardener is not particularly limited, but from the viewpoint of more fully obtaining the effect of improving heat resistance and the effect of reducing dielectric tangent, compounds having one or more highly reactive ester groups in one molecule, such as phenol esters, thiophenol esters, N-hydroxyamine esters, and esters of heterocyclic hydroxy compounds, are preferably used. More specific examples of ester-based hardeners include "EPICLON HPC8000-65T", "EPICLON HPC8000-L-65MT", and "EPICLON HPC8150-60T" (all trade names manufactured by DIC Corporation). These can be used alone or in combination of two or more.

During the curing reaction, the ester-based curing agent is thought to react with the crosslinking component (B) as shown in the following formula (I). In the reaction between the ester-based curing agent (C) and the crosslinking component (B), no hydroxyl groups are produced, and even if a side reaction occurs, hydroxyl groups are unlikely to be produced. As a result, it is thought that a low dielectric tangent can be achieved.

式中、Ｒ^１、Ｒ^２及びＲ^３はそれぞれ独立に、１価の有機基を示すが、本発明の効果がより十分に得られることから、芳香環を有する１価の有機基であってもよい。

In the formula, R ¹ , R ² and R ³ each independently represent a monovalent organic group, but may be a monovalent organic group having an aromatic ring, since this allows the effects of the present invention to be more fully obtained.

The resin composition may contain other curing agents besides the ester-based curing agent (C) to the extent that the effect of the present invention is not significantly impaired. From the viewpoint of more sufficiently reducing the dielectric tangent of the elastic resin layer, the content of the other curing agent is preferably less than 10 parts by mass per 100 parts by mass of the ester-based curing agent (C).

In the resin composition, the total content of the (B) crosslinking component and the (C) ester-based hardener is preferably 5 to 40% by mass, more preferably 10 to 35% by mass, and even more preferably 15 to 30% by mass, based on the total amount of the (A) rubber component, the (B) crosslinking component, and the (C) ester-based hardener. When the total content of the (B) crosslinking component and the (C) ester-based hardener is 5% by mass or more, more sufficient hardening is easily obtained, and the elastic resin layer tends to have particularly excellent properties in terms of adhesion, insulation reliability, and heat resistance. When the total content of the (B) crosslinking component and the (C) ester-based hardener is 40% by mass or less, more sufficient elasticity is easily obtained, and the rubber component and the crosslinking component tend to mix well.

In the resin composition, the content ratio of the (B) crosslinking component to the (C) ester-based hardener is preferably in the range of 4:5 to 5:4, in terms of the equivalent ratio of the epoxy groups in the (B) epoxy resin to the ester bonds in the (C) ester-based hardener. By having the content ratio within the above range, more sufficient hardening is easily achieved, and the elastic resin layer tends to have particularly excellent properties in terms of adhesion, insulation reliability, and heat resistance.

The resin composition may further contain (D) a curing accelerator. (D) The curing accelerator is a compound that functions as a catalyst for the curing reaction. (D) The curing accelerator may be selected from tertiary amines, imidazoles, organic acid metal salts, phosphorus compounds, Lewis acids, amine complex salts, and phosphines. Among these, imidazole may be used from the viewpoint of storage stability and curing properties of the varnish of the resin composition. (A) When the rubber component contains rubber partially modified with maleic anhydride, an imidazole compatible with this may be selected.

In the resin composition, the content of the (D) curing accelerator may be 0.1 to 10 parts by mass relative to 100 parts by mass of the total amount of the (A) rubber component, the (B) crosslinking component, and the (C) ester-based curing agent. If the content of the (D) curing accelerator is 0.1 parts by mass or more, there is a tendency that more sufficient curing is easily obtained. If the content of the (D) curing accelerator is 10 parts by mass or less, there is a tendency that more sufficient heat resistance is easily obtained. From the above viewpoints, the content of the (D) curing accelerator may be 0.3 to 7 parts by mass, or 0.5 to 5 parts by mass.

In addition to the above components, the resin composition may further contain antioxidants, anti-yellowing agents, ultraviolet absorbers, visible light absorbers, colorants, plasticizers, stabilizers, fillers, flame retardants, leveling agents, etc., as necessary, to the extent that the effects of the present invention are not significantly impaired.

In particular, the resin composition may contain at least one deterioration inhibitor selected from the group consisting of antioxidants, heat stabilizers, light stabilizers, and hydrolysis inhibitors. The antioxidant suppresses deterioration due to oxidation. The antioxidant also imparts sufficient heat resistance at high temperatures to the elastic resin layer. The heat stabilizer imparts stability at high temperatures to the elastic resin layer. Examples of light stabilizers include ultraviolet absorbers that prevent deterioration due to ultraviolet rays, light blocking agents that block light, and quenchers that have a quenching function that receives light energy absorbed by an organic material and stabilizes the organic material. The hydrolysis inhibitor suppresses deterioration due to moisture. The deterioration inhibitor may be at least one selected from the group consisting of antioxidants, heat stabilizers, and ultraviolet absorbers. As the deterioration inhibitor, only one of the components exemplified above may be used, or two or more may be used in combination. In order to obtain a better effect, two or more deterioration inhibitors may be used in combination.

The antioxidant may be, for example, one or more selected from the group consisting of phenol-based antioxidants, amine-based antioxidants, sulfur-based antioxidants, and phosphite-based antioxidants. To obtain a more excellent effect, two or more antioxidants may be used in combination. A phenol-based antioxidant and a sulfur-based antioxidant may be used in combination.

The phenolic antioxidant may be a compound having a substituent with large steric hindrance, such as a tertiary butyl group or a trimethylsilyl group, at the ortho position of the phenolic hydroxyl group. The phenolic antioxidant is also called a hindered phenolic antioxidant.

The phenolic antioxidant may be, for example, one or more compounds selected from the group consisting of 2-t-butyl-4-methoxyphenol, 3-t-butyl-4-methoxyphenol, 2,6-di-t-butyl-4-ethylphenol, 2,2'-methylene-bis(4-methyl-6-t-butylphenol), 4,4'-thiobis-(3-methyl-6-t-butylphenol), 4,4'-butylidenebis(3-methyl-6-t-butylphenol), 1,1,3-tris(2-methyl-4-hydroxy-5-t-butylphenyl)butane, 1,3,5-trimethyl-2,4,6-tris(3,5-di-t-butyl-4-hydroxybenzyl)benzene, and tetrakis-[methylene-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate]methane. The phenolic antioxidant may be a polymeric phenolic antioxidant such as 1,3,5-trimethyl-2,4,6-tris(3,5-di-t-butyl-4-hydroxybenzyl)benzene and tetrakis-[methylene-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate]methane.

Examples of phosphite antioxidants include triphenyl phosphite, diphenyl isodecyl phosphite, phenyl diisodecyl phosphite, 4,4'-butylidene-bis(3-methyl-6-t-butylphenyl ditridecyl) phosphite, cyclic neopentane tetrayl bis(nonylphenyl) phosphite, cyclic neopentane tetrayl bis(dinonylphenyl) phosphite, cyclic neopentane tetrayl tris(nonylphenyl) phosphite, and cyclic neopentane tetrayl tris(nonylphenyl) phosphite. It may be one or more compounds selected from the group consisting of 10-(2,5-dihydroxyphenyl)-10H-9-oxa-10-phosphaphenanthrene-10-oxide, 2,2-methylenebis(4,6-di-t-butylphenyl)-2-ethylhexyl phosphite, diisodecyl pentaerythritol diphosphite, and tris(2,4-di-t-butylphenyl)phosphite, or it may be tris(2,4-di-t-butylphenyl)phosphite.

Other examples of antioxidants include hydroxylamine-based antioxidants such as N-methyl-2-dimethylaminoacetohydroxamic acid, and sulfur-based antioxidants such as dilauryl 3,3'-thiodipropionate.

The content of the antioxidant may be 0.1 to 20% by mass based on the mass (total solid content) of the resin composition. If the content of the antioxidant is 0.1% by mass or more, sufficient heat resistance of the elastic resin layer is likely to be obtained. If the content of the antioxidant is 20% by mass or less, bleeding and blooming can be suppressed.

The molecular weight of the antioxidant may be 400 or more, 600 or more, or 750 or more from the viewpoint of preventing sublimation during heating. When two or more types of antioxidants are included, the average of their molecular weights may be within the above range.

Heat stabilizers (thermal deterioration inhibitors) include metal soaps or inorganic acid salts such as a combination of zinc and barium salts of higher fatty acids, organotin compounds such as organotin maleates and organotin mercaptides, and fullerenes (e.g., fullerene hydroxide).

Examples of ultraviolet absorbers include benzophenone-based ultraviolet absorbers such as 2,4-dihydroxybenzophenone, benzotriazole-based ultraviolet absorbers such as 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, and cyanoacrylate-based ultraviolet absorbers such as 2-ethylhexyl-2-cyano-3,3'-diphenylacrylate.

Examples of hydrolysis inhibitors include carbodiimide derivatives, epoxy compounds, isocyanate compounds, acid anhydrides, oxazoline compounds, and melamine compounds.

Other examples of anti-degradants include hindered amine light stabilizers, ascorbic acid, propyl gallate, catechin, oxalic acid, malonic acid, and phosphites.

The elastic resin layer can be produced, for example, by a method including dissolving or dispersing (A) a rubber component, (B) a crosslinking component, and (C) an ester-based curing agent, as well as other components as necessary, in an organic solvent to obtain a resin varnish, and forming the resin varnish onto a conductor foil or a carrier film by a method described below.

The organic solvent used here is not particularly limited, but examples thereof include aromatic hydrocarbons such as toluene, xylene, mesitylene, cumene, and p-cymene; cyclic ethers such as tetrahydrofuran and 1,4-dioxane; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, and 4-hydroxy-4-methyl-2-pentanone; esters such as methyl acetate, ethyl acetate, butyl acetate, methyl lactate, ethyl lactate, and γ-butyrolactone; carbonates such as ethylene carbonate and propylene carbonate; and amides such as N,N-dimethylformamide, N,N-dimethylacetamide, and N-methylpyrrolidone. From the viewpoint of solubility and boiling point, toluene or N,N-dimethylacetamide may be used. These organic solvents may be used alone or in combination of two or more kinds. The solid content (components other than the organic solvent) concentration in the resin varnish may be 20 to 80% by mass.

The carrier film is not particularly limited, but examples thereof include polyesters such as polyethylene terephthalate (PET), polybutylene terephthalate, and polyethylene naphthalate; polyolefins such as polyethylene and polypropylene; and films of polycarbonate, polyamide, polyimide, polyamideimide, polyetherimide, polyethersulfide, polyethersulfone, polyetherketone, polyphenylene ether, polyphenylene sulfide, polyarylate, polysulfone, and liquid crystal polymers. Among these, from the viewpoint of flexibility and toughness, films of polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polypropylene, polycarbonate, polyamide, polyimide, polyamideimide, polyphenylene ether, polyphenylene sulfide, polyarylate, or polysulfone may be used as the carrier film.

The thickness of the carrier film is not particularly limited, but may be 3 to 250 μm. If the thickness of the carrier film is 3 μm or more, the film strength is sufficient, and if the thickness of the carrier film is 250 μm or less, sufficient flexibility is obtained. From the above viewpoints, the thickness may be 5 to 200 μm, or 7 to 150 μm. From the viewpoint of improving the peelability from the elastic resin layer, a film in which the carrier film has been subjected to a release treatment using a silicone-based compound, a fluorine-containing compound, or the like may be used as necessary.

If necessary, a protective film may be attached onto the elastic resin layer to form a three-layer laminate film consisting of a conductor foil or carrier film, an elastic resin layer, and a protective film.

The protective film is not particularly limited, and examples thereof include films of polyesters such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate; and polyolefins such as polyethylene and polypropylene. Among these, from the viewpoint of flexibility and toughness, films of polyesters such as polyethylene terephthalate, and polyolefins such as polyethylene and polypropylene may be used as the protective film. From the viewpoint of improving peelability from the elastic resin layer, the protective film may be subjected to a release treatment using a silicone-based compound, a fluorine-containing compound, or the like.

The thickness of the protective film may vary depending on the desired flexibility, but may be 10 to 250 μm. A thickness of 10 μm or more tends to provide sufficient film strength, while a thickness of 250 μm or less tends to provide sufficient flexibility. From the above perspective, the thickness may be 15 to 200 μm, or 20 to 150 μm.

[Method of Manufacturing Wiring Board]
A wiring board having a conductor foil according to one embodiment can be manufactured by a method including, for example, a step of preparing a laminate (conductor board) having an elastic resin layer and a conductor foil laminated on the elastic resin layer, a step of forming an etching resist on the conductor foil, a step of exposing the etching resist and developing the exposed etching resist to form a resist pattern that covers a portion of the conductor foil, a step of removing a portion of the conductor foil that is not covered by the resist pattern, and a step of removing the resist pattern.

Any method may be used to obtain a laminate (conductor substrate) having an elastic resin layer and a conductor foil, including a method of applying a varnish of a resin composition for forming an elastic resin layer to a conductor foil, and a method of laminating a conductor foil to an elastic resin layer formed on a carrier film using a vacuum press, a laminator, or the like. The elastic resin layer can be formed by heating the resin composition to promote a crosslinking reaction (curing reaction) of the crosslinking component.

The elastic resin layer on the carrier film may be laminated onto the conductor foil by any method, including a roll laminator, a vacuum laminator, a vacuum press, etc. From the viewpoint of production efficiency, molding may be performed using a roll laminator or a vacuum laminator.

The thickness of the elastic resin layer after drying is not particularly limited, but is usually 5 to 1000 μm. Within this range, the elastic resin layer is likely to have sufficient strength, and drying can be performed sufficiently, reducing the amount of residual solvent in the elastic resin layer.

A laminate having conductor foil formed on both sides of the elastic resin layer may be produced by further laminating a conductor foil on the side of the elastic resin layer opposite the conductor foil. By providing conductor layers on both sides of the elastic resin layer, warping of the laminate during curing can be suppressed.

A method for forming a wiring pattern on the conductor foil of a laminate (a laminate for forming a wiring board) generally involves a method using etching or the like. For example, when copper foil is used as the conductor foil, the etching solution can be, for example, a mixture of concentrated sulfuric acid and hydrogen peroxide, or a ferric chloride solution.

Examples of etching resists used in etching include Photec H-7025 (trade name, manufactured by Hitachi Chemical Co., Ltd.), Photec H-7030 (trade name, manufactured by Hitachi Chemical Co., Ltd.), and X-87 (trade name, manufactured by Taiyo Holdings Co., Ltd.). The etching resist is usually removed after the wiring pattern is formed.

One embodiment of a method for manufacturing a wiring board having a conductor plating film includes the steps of forming a conductor plating film on a stretchable resin layer by electroless plating, forming a plating resist on the conductor plating film, exposing the plating resist and developing the exposed plating resist to form a resist pattern that covers a portion of the stretchable resin layer, forming a further conductor plating film by electrolytic plating on the portion of the conductor plating film that is not covered by the resist pattern, removing the resist pattern, and removing the portion of the conductor plating film formed by electroless plating that is not covered by the conductor plating film formed by electrolytic plating.

Yet another embodiment of the method for manufacturing a wiring board includes a step of forming an etching resist on a conductive plating film formed on an elastic resin layer, a step of exposing the etching resist and developing the exposed etching resist to form a resist pattern that covers a portion of the elastic resin layer, a step of removing the conductive plating film from a portion not covered by the resist pattern, and a step of removing the resist pattern.

Examples of plating resists used as masks for plating include Photec RY3325 (product name, manufactured by Hitachi Chemical Co., Ltd.), Photec RY-5319 (product name, manufactured by Hitachi Chemical Co., Ltd.), and MA-830 (product name, manufactured by Taiyo Holdings Co., Ltd.). Other details of electroless plating and electrolytic plating are as described above.

By mounting various electronic elements on the wiring board, a stretchable device can be obtained.

The present invention will be described in more detail with reference to the following examples. However, the present invention is not limited to these examples.

Example 1
<Preparation of Resin Varnish for Forming Elastic Resin Layer>
As the (A) component, 80 parts by mass (amount of non-volatile content) of maleic anhydride-modified styrene-ethylene-butadiene rubber (manufactured by KRATON Corporation, trade name "FG1924GT") diluted with toluene to a non-volatile content of 25% by mass, as the (B) component, 11.1 parts by mass (amount of non-volatile content) of dicyclopentadiene-type epoxy resin (manufactured by DIC Corporation, trade name "EPICLON HP7200H") diluted with toluene to a non-volatile content of 25% by mass, as the (C) component, 8.9 parts by mass (amount of non-volatile content) of an ester-based curing agent (manufactured by DIC Corporation, trade name "HPC8000-65T", dicyclopentadiene-type diphenol compound) diluted with toluene to a non-volatile content of 25% by mass, and as the (D) component, 3 parts by mass of 1-benzyl-2-methylimidazole (manufactured by Shikoku Kasei Corporation, trade name "1B2MZ") were mixed with stirring to obtain a resin varnish.

<Preparation of Laminated Film>
A release-treated polyethylene terephthalate (PET) film (manufactured by Teijin DuPont Films Co., Ltd., product name "Purex A31", thickness 25 μm) was prepared as a carrier film. The above-mentioned resin varnish was applied to the release-treated surface of this PET film using a knife coater (manufactured by Yasui Seiki Co., Ltd., product name "SNC-350"). The coating film was dried by heating at 100 ° C. for 20 minutes in a dryer (manufactured by Futaba Scientific Co., Ltd., product name "MSO-80TPS") to form a resin layer (elastic resin layer before curing) having a thickness of 100 μm. A release-treated PET film identical to the carrier film was attached to the formed resin layer as a protective film with the release-treated surface facing the resin layer side, to obtain a laminated film.

<Preparation of Conductive Substrate>
The protective film of the laminated film was peeled off, and an electrolytic copper foil (manufactured by Furukawa Electric Co., Ltd., product name "F2-WS-12") having a roughened surface with a surface roughness Ra of 1.5 μm was laminated on the exposed resin layer with the roughened surface facing the resin layer. In this state, the electrolytic copper foil was laminated to the resin layer using a vacuum pressure laminator (manufactured by Nikko Materials Co., Ltd., product name "V130") under conditions of a pressure of 0.5 MPa, a temperature of 90°C, and a pressure time of 60 seconds. Thereafter, the resin layer was heated at 180°C for 60 minutes in a dryer (manufactured by Futaba Scientific Co., Ltd., product name "MSO-80TPS") to obtain a conductor substrate having an elastic resin layer, which is a cured product of the resin layer, and an electrolytic copper foil as a conductor layer.

(Examples 2 to 6 and Comparative Examples 1 and 2)
A resin varnish, a laminated film, and a conductor substrate were produced in the same manner as in Example 1, except that the composition of the resin varnish was changed to the composition shown in Table 1. In Table 1, "HP5000" is a novolac type epoxy resin (manufactured by DIC Corporation, product name "EPICLON HP5000"), "HPC8000-L-65MT" is an ester-based curing agent (manufactured by DIC Corporation, product name "EPICLON HPC8000-L-65MT", a low molecular weight grade of HPC8000-65T), and "HPC8150-60T" is an ester-based curing agent (manufactured by DIC Corporation, product name "EPICLON HPC8150-60T", a compound having a naphthalene skeleton). The amount of each component in Table 1 is the amount of non-volatile matter, and the unit is "parts by mass".

[Measurement of tensile modulus and elongation at break]
The laminated films obtained in the examples and comparative examples were heated at 180°C for 60 minutes to harden the resin layer, forming an elastic resin layer. The carrier film and protective film were removed, and the elastic resin layer was cut into strips of 40 mm length and 10 mm width to obtain a test piece. A tensile test of this test piece was performed using an autograph (manufactured by Shimadzu Corporation, product name "EZ-S") to obtain a stress-strain curve. The tensile modulus and breaking elongation were obtained from the obtained stress-strain curve. The tensile test was performed under conditions of a chuck distance of 20 mm and a tensile speed of 50 mm/min. The tensile modulus was obtained from the slope of the stress-strain curve in the stress range of 0.5 to 1.0 N. The strain at the time when the test piece broke was recorded as the breaking elongation. The results are shown in Table 1.

[Measurement of recovery rate]
In the same manner as in the measurement of the tensile modulus and elongation at break, a strip-shaped elastic resin layer test piece having a length of 40 mm and a width of 10 mm was prepared. This test piece was stretched to a strain of 20% at a tensile speed of 100 mm/min using an autograph (manufactured by Shimadzu Corporation, product name "EZ-S"), and then the stress was released and returned to the initial position, and a tensile test was performed again. The recovery rate R was calculated by the following formula, where X is the strain (displacement) applied in the first tensile test, and Y is the difference between the position at which the load begins to be applied when the tensile test is performed again and X. In this test, X is 20%. The results are shown in Table 1.
R(%)=Y/X×100

[Measurement of dielectric constant (Dk) and dielectric loss tangent (Df)]
In the same manner as in the measurement of the tensile modulus and elongation at break, a test piece of the elastic resin layer having a size of 80 mm x 80 mm was prepared. Using this test piece, Dk and Df were calculated by the cavity resonator method. Measurements were performed under conditions of an ambient temperature of 25°C and a frequency of 10 kHz using vector network analyzers E8364B (manufactured by Keysight Technologies), CP531 (manufactured by Kanto Electronics Application Development Co., Ltd.), and CPMA-V2 (program), respectively. The results are shown in Table 1.

[Evaluation of heat resistance]
The laminated films obtained in Examples 1 to 6 and Comparative Examples 1 and 2 were heated at 180°C for 60 minutes to harden the resin layer, forming an elastic resin layer. After removing the carrier film and protective film, a heat resistance test was performed in which the elastic resin layer was heat-treated 10 times using a nitrogen reflow system (manufactured by Tamura Manufacturing Co., Ltd., product name "TNV-EN") with the temperature profile of Figure 3 conforming to IPC/JEDEC J-STD-020. After the heat resistance test, the tensile modulus, breaking elongation and recovery rate of the elastic resin layer were measured in the same manner as above. The results are shown in Tables 2 and 3 together with the measurement results before the heat resistance test.

[Measurement of infrared absorption spectrum (IR)]
The resin layer (elastic resin layer before curing) of the laminated film of Comparative Example 1 and the elastic resin layer after heating it at 180 ° C. for 60 minutes and curing it, and the resin layer of the laminated film of Examples 1 and 3 after heating it at 180 ° C. for 60 minutes and curing it, the carrier film and the protective film were removed, and then the infrared absorption spectrum was measured by a transmission method using a Fourier transform infrared spectrophotometer (manufactured by Bio-Rad, product name "FTS3000MX"). Figure 4 shows the infrared absorption spectrum of the elastic resin layer before and after curing of Comparative Example 1, and Figure 5 shows the infrared absorption spectrum of the elastic resin layer after curing of Examples 1, 3 and Comparative Example 1, respectively.

As shown in Figure 4, in the elastic resin layer of Comparative Example 1, after curing, an absorption peak at about 3400 cm ^-1 attributed to the stretching vibration of the hydroxyl group that was not present before curing appeared, confirming that hydroxyl groups were generated by the curing reaction. Also, as shown in Figure 5, in the elastic resin layers of Examples 1 and 3, there was almost no absorption peak attributable to the stretching vibration of the hydroxyl group, confirming that the generation of hydroxyl groups was suppressed.

[Fabrication and evaluation of wiring board]
As shown in FIG. 2, a test wiring board 1 having an elastic resin layer 3 and a conductor foil (electrolytic copper foil) having a wave pattern formed on the elastic resin layer 3 as a conductor layer 5 was prepared. First, an etching resist (manufactured by Hitachi Chemical Co., Ltd., product name "Photec RY-5325") was attached to the conductor layer of the conductor board obtained in the examples and comparative examples in which the elastic resin layer surface was unevenly formed, using a roll laminator, and a phototool having a wave pattern formed thereon was adhered to it. The etching resist was exposed to an energy amount of 50 mJ/cm ² using an EXM-1201 exposure machine manufactured by Oak Seisakusho Co., Ltd. Next, spray development was performed for 240 seconds with a 1% by mass sodium carbonate aqueous solution at 30 ° C., dissolving the unexposed parts of the etching resist, and a resist pattern having wave-shaped openings was formed. Next, the copper foil in the parts not covered by the resist pattern was removed by an etching solution. Thereafter, the etching resist was removed with a stripping solution to obtain a wiring board 1 having, on the elastic resin layer 3, a conductor layer 5 forming a wavy wiring pattern meandering along a predetermined direction X with a wiring width of 50 μm.

The obtained wiring board was tensile deformed in the X direction to a strain of 10%, and then returned to its original state, and the elastic resin layer and the wavy wiring pattern were observed. As a result, in both the example and comparative example wiring boards, no breakage occurred in the elastic resin layer or the wiring pattern when stretched.

As is clear from the results shown in Table 1, it was confirmed that the conductor substrates of Examples 1 to 6 have excellent elasticity and a low dielectric tangent compared to the conductor substrates of Comparative Examples 1 and 2. In addition, as is clear from the results shown in Tables 2 and 3, it was confirmed that the conductor substrates of Examples 1 to 6 can maintain good elasticity and elastic modulus even after the heat resistance test.

The conductor substrate of the present invention and the wiring substrate obtained from it are expected to be used, for example, as substrates for wearable devices.

1...wiring board, 3...elastic resin layer, 5...conductor layer (conductor foil or conductor plating film).

Claims (13)

An elastic resin layer;
A conductive substrate having a conductive plating film provided on the elastic resin layer,
the elastic resin layer comprises a cured product of a resin composition containing (A) a rubber component, (B) a cross-linking component having an epoxy group, and (C) an ester-based curing agent;
A conductive substrate, wherein the elastic resin layer has a recovery rate of 80% or more after being tensile-deformed to a strain of 20%. The conductive substrate according to claim 1, wherein the (A) rubber component contains at least one rubber selected from the group consisting of acrylic rubber, isoprene rubber, butyl rubber, styrene butadiene rubber, butadiene rubber, acrylonitrile butadiene rubber, silicone rubber, urethane rubber, chloroprene rubber, ethylene propylene rubber, fluororubber, vulcanized rubber, epichlorohydrin rubber, and chlorinated butyl rubber. The conductive substrate according to claim 1 or 2, wherein the rubber component (A) includes a rubber having a crosslinking group. The conductive substrate according to claim 3, wherein the crosslinking group is at least one of an acid anhydride group and a carboxyl group. The conductive substrate according to any one of claims 1 to 4, wherein the resin composition further contains (D) a curing accelerator. The conductive substrate according to any one of claims 1 to 5, wherein the content of the rubber component (A) in the resin composition is 60 to 95 mass% based on the total amount of the rubber component (A), the cross-linking component (B), and the ester-based hardener (C). The conductive substrate according to any one of claims 1 to 6, wherein the resin composition further contains an antioxidant. A wiring board comprising the conductor substrate according to any one of claims 1 to 7, in which the conductor plating film forms a wiring pattern. A stretchable device comprising the wiring board according to claim 8 and an electronic element mounted on the wiring board. The conductor substrate according to any one of claims 1 to 7, which is used to form a wiring substrate, includes a conductor substrate having a stretchable resin layer and a conductor plating film provided on the stretchable resin layer, the conductor plating film forming a wiring pattern. forming a plating resist on the elastic resin layer;
A step of exposing the plating resist and developing the exposed plating resist to form a resist pattern that covers a part of the elastic resin layer;
forming a conductive plating film by electroless plating on a surface of the elastic resin layer in a portion not covered by the resist pattern;
The method for manufacturing a wiring board according to claim 8 , further comprising the step of: removing the resist pattern. forming a conductive plating film on the elastic resin layer by electroless plating;
forming a plating resist on the conductor plating film;
A step of exposing the plating resist and developing the exposed plating resist to form a resist pattern that covers a part of the elastic resin layer;
forming a further conductive plating film by electrolytic plating on the conductive plating film in the portion not covered by the resist pattern;
removing the resist pattern;
9. The method for producing a wiring board according to claim 8, further comprising the step of removing a portion of the conductive plating film formed by electroless plating that is not covered by the conductive plating film formed by electrolytic plating. forming an etching resist on the conductor plating film formed on the elastic resin layer;
A step of exposing the etching resist and developing the exposed etching resist to form a resist pattern that covers a part of the elastic resin layer;
removing the conductor plating film from the portion not covered by the resist pattern;
removing the resist pattern;
The method for manufacturing the wiring substrate according to claim 8 , comprising:

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