CN112088089A

CN112088089A - Conductor substrate, wiring substrate, stretchable element, and method for manufacturing wiring substrate

Info

Publication number: CN112088089A
Application number: CN201980030870.4A
Authority: CN
Inventors: 小川祯宏; 正木刚史; 川守崇司; 沈唐伊
Original assignee: Showa Denko KK
Current assignee: Resonac Holdings Corp
Priority date: 2018-05-11
Filing date: 2019-05-10
Publication date: 2020-12-15
Also published as: JP7468611B2; JP7468609B2; TW201946777A; JPWO2019216425A1; JP2023029400A; JP7468610B2; JP2023029399A; KR20210007956A; JP2023029398A; WO2019216425A1; JP7338621B2

Abstract

A conductor substrate has a stretchable resin layer; and a conductor foil provided on the stretchable resin layer. The stretchable resin layer contains a cured product of a resin composition containing (A) a rubber component, (B) a crosslinking component having an epoxy group, and (C) an ester-based curing agent.

Description

Conductor substrate, wiring substrate, stretchable element, and method for manufacturing wiring substrate

Technical Field

An aspect of the present invention relates to a wiring substrate that can have high stretchability and a method of manufacturing the same. Another aspect of the present invention relates to a conductor substrate that can be used to form the wiring substrate. Still another aspect of the present invention relates to a stretchable component using the wiring substrate.

Background

In recent years, in the fields of wearable devices, health care (health care) related devices, and the like, for example, there is a need for flexibility and stretchability that can be used along curved surfaces or joints of the body and that are less likely to cause poor connection even when worn or removed. To constitute such a device, a wiring board or a base material having high flexibility is required.

Patent document 1 describes a method for sealing a semiconductor device such as a memory chip (memory chip) with a stretchable resin composition. Patent document 1 mainly studies the use of a stretchable resin composition for sealing.

Documents of the prior art

Patent document

Patent document 1: international publication No. 2016/080346

Disclosure of Invention

Problems to be solved by the invention

As described in patent document 1, by providing the sealing material with stretchability, a stretchable member that is difficult to be realized by a conventional sealing material can be realized. On the other hand, the base substrate does not have stretchability, and therefore it is difficult to have higher stretchability. Therefore, a wiring board having higher flexibility is required.

In addition, in view of improvement in heat resistance, use of a crosslinking component having a reactive functional group as a material for a base substrate for manufacturing a wiring board has been studied. However, when a crosslinking component having a reactive functional group is used, there are problems as follows: the dielectric loss tangent (dielectric loss 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.

Under such circumstances, an object of an aspect of the present invention is to provide a conductor substrate having high stretchability and a low dielectric loss tangent, a wiring board using the conductor substrate, a stretchable element, and a method for manufacturing the wiring board.

Means for solving the problems

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

Another aspect of the present invention provides a conductor substrate having: a stretchable resin layer; and a conductor plating film provided on the stretchable resin layer. The stretchable resin layer contains a cured product of a resin composition containing (A) a rubber component, (B) a crosslinking component having an epoxy group, and (C) an ester-based curing agent.

According to the conductor substrate, by using the stretchable resin layer containing the rubber component (a) as its base substrate, high stretchability can be obtained. In addition, it is considered that the reason why the dielectric loss tangent is increased in the case of using a crosslinking component having a reactive functional group as a material for producing the stretchable resin layer has been: the crosslinking component generates hydroxyl groups at the time of hardening reaction. Hydroxyl groups are functional groups that are small in size and highly polarizable, and thus a material having hydroxyl groups will increase the dielectric loss tangent as a whole. On the other hand, the present inventors have found that the generation of hydroxyl groups upon the curing reaction of the crosslinking component can be greatly suppressed by using (B) a crosslinking component having an epoxy group as the crosslinking component in combination with (C) an ester-based curing agent as the curing agent. The reason for this is that: the curing reaction between the epoxy group of the crosslinking component and the ester-based curing agent does not involve the generation of a hydroxyl group, and a hydroxyl group is hardly generated even after curing. Further, these cured products do not adversely affect the stretchability. Therefore, according to the conductor substrate having the above-described structure, a low dielectric loss tangent is achieved by using a crosslinking component which can maintain high stretchability and can improve heat resistance.

Another aspect of the present invention provides a wiring board comprising the conductor substrate of the present invention, wherein the conductor foil or the conductor plating film forms a wiring pattern. The wiring board is a board on which a wiring pattern is formed by the conductor foil or the conductor plating film in the conductor board of the present invention, and the wiring board includes the stretchable resin layer having the specific structure, and therefore has high stretchability, and has high heat resistance by using the crosslinking component, and can have a low dielectric loss tangent, and the transmission loss of the wiring pattern can be sufficiently reduced.

Another aspect of the present invention provides a telescopic element comprising: the wiring board of the present invention; and an electronic device mounted on the wiring board. The stretchable element includes the wiring board of the present invention and the stretchable resin layer having the specific structure, and thus has high stretchability, and has high heat resistance and a low dielectric loss tangent by using the crosslinking component, and the transmission loss of the wiring pattern can be sufficiently reduced.

Another aspect of the present invention provides a conductor substrate of the present invention, which is used to form a wiring substrate. The wiring board includes a conductor substrate having a stretchable resin layer and a conductor foil or a conductor plating film provided on the stretchable resin layer, the conductor foil or the conductor plating film forming a wiring pattern.

Another aspect of the present invention provides a method of manufacturing the wiring substrate of the present invention, comprising: preparing a laminate sheet having a stretchable resin layer and a conductor foil laminated on the stretchable resin layer; a step of forming an etching resist on the conductor foil; exposing the etching resist to light and developing the exposed etching resist to form a resist pattern covering a part of the conductor foil; a step of removing the conductor foil of a portion not covered with the resist pattern; and a step of removing the resist pattern.

Another aspect of the present invention provides a method of manufacturing the wiring substrate of the present invention, comprising: a step of forming a plating resist on the stretchable resin layer; exposing the plating resist to light and developing the exposed plating resist to form a resist pattern covering a part of the stretchable resin layer; a step of forming a conductor plating film by electroless plating on a surface of a portion of the stretchable resin layer not covered with the resist pattern; and a step of removing the resist pattern.

Another aspect of the present invention provides a method of manufacturing the wiring substrate of the present invention, comprising: a step of forming a conductor plating film on the stretchable resin layer by electroless plating; a step of forming a plating resist on the conductor plating film; exposing the plating resist to light and developing the exposed plating resist to form a resist pattern covering a part of the stretchable resin layer; a step of further forming a conductor plating film by electroplating on the conductor plating film of a portion not covered with the resist pattern; a step of removing the resist pattern; and a step of removing a portion of the conductor plating film formed by electroless plating that is not covered by the conductor plating film formed by electroplating.

Another aspect of the present invention provides a method of manufacturing the wiring substrate of the present invention, comprising: a step of forming an etching resist on the conductor plating film formed on the stretchable resin layer; exposing the etching resist to light and developing the exposed etching resist to form a resist pattern covering a part of the stretchable resin layer; a step of removing the conductor plating film of a portion not covered with the resist pattern; and a step of removing the resist pattern.

The wiring board of the present invention in which the wiring pattern is formed by the conductor foil or the conductor plating film can be efficiently manufactured by the manufacturing method.

ADVANTAGEOUS EFFECTS OF INVENTION

According to an aspect of the present invention, a conductor substrate having high stretchability and a low dielectric loss tangent, a wiring substrate using the conductor substrate, a stretchable element, and a method for manufacturing the wiring substrate can be provided.

Drawings

FIG. 1 is a stress-strain curve showing an example of measurement of the recovery rate.

FIG. 2 is a plan view showing an embodiment of a wiring board.

FIG. 3 is a graph showing a temperature distribution (profile) of a heat resistance test.

FIG. 4 is a graph showing the infrared absorption spectrum of the stretchable resin layer before and after curing in comparative example 1.

FIG. 5 is a graph showing the infrared absorption spectra of the cured stretchable resin layers of examples 1 and 3 and comparative example 1.

Detailed Description

Hereinafter, several embodiments of the present invention will be described in detail. However, the present invention is not limited to the following embodiments.

A conductor substrate of one embodiment, which has a stretchable resin layer; and a conductor layer provided on one surface or both surfaces of the stretchable resin layer. The stretchable resin layer contains a cured product of a resin composition containing (A) a rubber component, (B) a crosslinking component having an epoxy group, and (C) an ester-based curing agent. The wiring board of one embodiment comprises a stretchable resin layer containing a cured product of the resin composition, and a conductor layer provided on one surface or both surfaces of the stretchable resin layer and having a wiring pattern formed thereon. The conductor layer can be a conductor foil or a conductor plating film.

< conductor substrate >

[ conductor foil ]

The elastic modulus of the conductor foil may be 40GPa to 300 GPa. When the elastic modulus of the conductor foil is 40GPa to 300GPa, the conductor foil tends to be less likely to break due to the elongation of the wiring board. From the same viewpoint, the elastic modulus of the conductor foil may be 50GPa or more, or 60GPa or more, or 280GPa or less, or 250GPa or less. The elastic modulus of the conductor foil 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 (permalloy) foil, 42alloy (42alloy) foil, Kovar (Kovar) foil, nickel-chromium (Nichrome) foil, beryllium copper foil, phosphor bronze foil, brass foil, zinc white copper 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 (Monel) foil, english high nickel alloy (Inconel) foil, hastelloy (hastelloy) foil, and the like. The conductor foil may be selected from copper foil, gold foil, nickel foil, and iron foil from the viewpoint of an appropriate elastic modulus and the like. From the viewpoint of wiring formability, the conductor foil may be a copper foil. The copper foil can be easily formed with a wiring pattern by photolithography without impairing the characteristics of the stretchable resin layer.

The copper foil is not particularly limited, and for example, an electrolytic copper foil and a rolled copper foil used for a copper-clad laminate, a flexible wiring board, and the like can be used. Examples of commercially available electrolytic copper foil include: F0-WS-18 (trade name, manufactured by Guhe electric industries, Ltd.), NC-WS-20 (trade name, manufactured by Guhe electric industries, Ltd.), YGP-12 (trade name, manufactured by Nippon electrolysis, Ltd.), GTS-18 (trade name, manufactured by Guhe electric industries, Ltd.), and F2-WS-12 (trade name, manufactured by Guhe electric industries, Ltd.). Examples of the rolled copper foil include: TPC foil (trade name, manufactured by JX Metal Ltd.), HA-V2 foil (trade name, manufactured by JX Metal Ltd.), and C1100R (trade name, manufactured by Mitsui Sumitomo Metal mine bronze Ltd.). From the viewpoint of adhesion to the stretchable resin layer, a roughened copper foil can be used. From the viewpoint of folding resistance, a rolled copper foil can be used.

The metal foil may have a roughened surface formed by roughening treatment. In this case, the metal foil is usually provided on the stretchable resin layer in an orientation in which the roughened surface is in contact with 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. The surface roughness Ra of the roughened surface may be 0.3 to 1.5 μm for easy formation of fine wiring.

The surface roughness Ra can be measured using, for example, a surface shape measuring apparatus Wyko NT9100 (manufactured by Veeco) under the following conditions.

Measurement conditions

Inner lens: 1 times of

An outer lens: 50 times of

Measurement range: 0.120X 0.095mm

And (3) measuring the depth: 10 μm

The measurement method comprises the following steps: vertical Scanning Interference (VSI) method

The thickness of the conductor foil is not particularly limited, and may be 1 μm 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 processing are particularly easy.

The conductor foil is provided on one or both surfaces of the stretchable resin layer. By providing the conductor foil on both surfaces of the stretchable resin layer, warpage due to heating for curing or the like can be suppressed.

The method of providing the conductor foil is not particularly limited, and there are, for example: a method of directly coating the metal foil with a resin composition for forming a stretchable resin layer; and a method in which a resin composition for forming a stretchable resin layer is applied to a carrier film (carrier film) to form a resin layer (stretchable resin layer before curing), and the formed resin layer is laminated on a conductor foil.

[ conductor coating film ]

The conductive plating film can be formed by a common plating method used in an additive method or a semi-additive method. For example, after a plating catalyst application treatment for adhesion of palladium is performed, the stretchable 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 layer (primer). Further electroplating (electro-plating) may be performed as necessary to adjust the thickness to a desired thickness. As the electroless plating solution used in the electroless plating, any electroless plating solution can be used, and is not particularly limited. The plating may be performed by a general method, and is not particularly limited. The conductor plating film (electroless plating film, plating film) may be a copper plating film in terms of cost and resistance value.

Further, the circuit layer can be formed by etching away unnecessary portions. The etching solution used for etching may be appropriately selected depending on the type of the plating layer. For example, when the conductor is copper-plated, a mixed solution of concentrated sulfuric acid and hydrogen peroxide water, an iron chloride solution, or the like can be used as an etching solution used for etching.

In order to improve the adhesion to the conductor plating film, irregularities may be formed in advance on the stretchable resin layer. As a method of forming the unevenness, for example, a method of transferring a roughened surface of a copper foil is cited. As the copper foil, YGP-12 (trade name, manufactured by Nippon electrolytic Co., Ltd.), GTS-18 (trade name, manufactured by Kogaku electric industries Co., Ltd.), or F2-WS-12 (trade name, manufactured by Kogaku electric industries Co., Ltd.) can be used, for example.

Examples of a method for transferring the roughened surface of the copper foil include: a method of directly coating the roughened surface of the copper foil with a resin composition for forming a stretchable resin layer; and a method of forming a resin layer (a stretchable resin layer before curing) on a copper foil after applying a resin composition for forming a stretchable resin layer to a carrier film. By forming the conductor plating films on both surfaces of the stretchable resin layer, warping due to heating for curing or the like can be suppressed.

The surface treatment of the stretchable resin layer can be performed for the purpose of high adhesion of the conductor plating film. Examples of the surface treatment include roughening treatment (desmear treatment), Ultraviolet (UV) treatment, and plasma treatment used in a general wiring board manufacturing process.

As the desmear treatment, a method used in a general wiring board manufacturing process, for example, a sodium permanganate aqueous solution can be used.

[ stretchable resin layer ]

The stretchable resin layer may have, for example, a stretchability such that the recovery rate after being subjected to tensile deformation to a strain of 20% is 80% or more. The recovery rate was determined in a tensile test using a measurement sample of a stretchable resin layer. Let X be the strain (displacement) applied in the first tensile test, and then Y be the difference between the position at which the load starts to be applied when returning to the initial position and performing the tensile test again, and by the formula: r (%) is calculated as (Y/X) × 100%, and is defined as the recovery rate. The recovery rate can be measured by setting X to 20%. Fig. 1 is a stress-strain curve showing a measurement example of the recovery rate. The recovery rate may be 80% or more, 85% or more, or 90% or more from the viewpoint of resistance to repeated use. The upper limit of the recovery rate is defined as 100%.

The elastic coefficient (tensile elastic coefficient) of the stretchable resin layer may be 0.1MPa or more and 1000MPa or less. When the modulus of elasticity is 0.1MPa or more and 1000MPa or less, the workability and flexibility as a base material tend to be particularly excellent. From the above viewpoint, the modulus of elasticity may be 0.3MPa or more and 100MPa or less, or 0.5MPa or more and 50MPa or less.

The elongation at break of the stretchable resin layer may be 100% or more. When the elongation at break is 100% or more, sufficient stretchability tends to be easily obtained. From the viewpoint described above, the elongation at break may be 150% or more, 200% or more, 300% or more, or 500% or more. The upper limit of the elongation at break is not particularly limited, and is usually about 1000% or less.

The dielectric loss tangent (Df) of the stretchable resin layer may be 0.004 or less. When the dielectric loss tangent is 0.004 or less, the transmission loss of the wiring pattern provided on the stretchable resin layer tends to be sufficiently reduced. From the above 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, and is usually about 0.0005 or more.

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

The stretchable resin layer may be a layer having no absorption peak of stretching vibration attributed to a hydroxyl group in its infrared absorption spectrum. This sufficiently reduces the dielectric loss tangent of the stretchable resin layer, and tends to sufficiently reduce the transmission loss of the wiring pattern provided on the stretchable resin layer.

The stretchable resin layer contains a cured product of a resin composition (curable resin composition) containing (A) a rubber component, (B) a crosslinking component having an epoxy group, and (C) an ester-based curing agent. That is, the stretchable resin layer contains (B) a crosslinked polymer having a crosslinking component of an epoxy group. The rubber component (A) can easily impart stretchability to the stretchable resin layer.

(A) The rubber component may include, for example, at least one rubber selected from the group consisting of acrylic rubber, isoprene rubber, butyl rubber, styrene butadiene rubber, acrylonitrile butadiene rubber, silicone rubber, urethane rubber, chloroprene rubber, ethylene propylene rubber, fluorine rubber, vulcanized rubber, epichlorohydrin rubber, and chlorinated butyl rubber. From the viewpoint of protecting the wiring from damage due to moisture absorption or the like, a rubber component having low air permeability may be used. From this viewpoint, (a) the rubber component may contain at least one selected from styrene butadiene rubber, and butyl rubber. By using the styrene butadiene rubber, the resistance of the stretchable resin layer to various chemical solutions used in the plating step can be improved, and the wiring board can be manufactured with high yield.

Examples of commercially available products of acrylic rubber include: "Nippon (Nipol) AR series" by Nippon (ZEON) Co., Ltd., and "Kramert (KURARITY) series" by Kramer (Kuraray) Co., Ltd., Japan.

Examples of commercially available products of isoprene rubber include: nippon (Nipol) IR series from Nippon Raynaud (ZEON) Inc.

Commercially available butyl rubber products include, for example: "Butai (BUTYL) series" by JSR corporation, and the like.

Commercially available products of styrene butadiene rubber include, for example: "Dynalone (Dynalon) SEBS series", "Dynalon (Dynalon) HSBR series" by JSR corporation, "Krotan (Kraton) D polymer series" by Komatam polymers (Kraton polymers Japan) corporation, and "AR series" by Akolon Kasei (Aronkasei) corporation.

Commercially available butadiene rubbers include, for example: "Niper (Nipol) BR series" of Nippon (ZEON) corporation, and the like.

Commercially available acrylonitrile butadiene rubber products include, for example: "JSR NBR series" from JSR corporation.

Commercially available products of silicone rubber include, for example: "KMP series" by Beacon Silicone corporation.

Examples of commercially available products of ethylene propylene rubber include: "JSR EP series" by JSR corporation, and the like.

Commercially available fluororubbers include, for example: daikin (Daikin) Inc. "Daidu (DAIEL) series" and the like.

Examples of commercially available epichlorohydrin rubbers include: "Black Delrin (Hydrin) series" from Rapulo (ZEON) of Japan.

(A) The rubber component may be produced by synthesis. For example, the acrylic rubber can be obtained by: (meth) acrylic acid, (meth) acrylic acid esters, aromatic vinyl compounds, vinyl cyanide compounds, and the like are reacted.

(A) The rubber component may also comprise a rubber having a crosslinking group. By using a rubber having a crosslinking group, the heat resistance of the stretchable resin layer tends to be easily improved. The crosslinking group may be a reactive group capable of causing a reaction of crosslinking the molecular chain of the rubber component (a). Examples thereof include: reactive groups, acid anhydride groups, amino groups, hydroxyl groups, epoxy groups and carboxyl groups of the crosslinking component (B) described later.

(A) The rubber component may also contain a rubber having at least one crosslinking group of an acid anhydride group and a carboxyl group. Examples of the rubber having an acid anhydride group include rubbers partially modified with maleic anhydride. The rubber partially modified with maleic anhydride is a polymer comprising structural units derived from maleic anhydride. As a commercially available product of a rubber partially modified with maleic anhydride, for example, there is a styrene-based elastomer "tafflorene (tuffrene) 912" manufactured by asahi chemical corporation.

The rubber partially modified with maleic anhydride may also be a hydrogenated styrene-based elastomer partially modified with maleic anhydride. The hydrogenated styrene elastomer is expected to have an effect of improving weather resistance and the like. The hydrogenated styrene elastomer is an elastomer obtained by addition reaction of hydrogen to an unsaturated double bond of a styrene elastomer having a soft segment containing an unsaturated double bond. Examples of commercially available products of hydrogenated styrene-based elastomers partially modified with maleic anhydride include "FG 1901" and "FG 1924" from Kraton polymers Japan, ltd, "tafutokai (TufTech) M1911", "tafutokai (TufTech) M1913" and "tafutokai (TufTech) M1943" from asahi chemicals.

The weight average molecular weight of the rubber component (A) may be 20000 to 200000, 30000 to 150000, or 50000 to 125000 from the viewpoint of film coatability. The weight average molecular weight (Mw) herein is a standard polystyrene conversion value obtained by Gel Permeation Chromatography (GPC).

The content of the rubber component (a) in the resin composition is preferably 60 to 95% by mass, more preferably 65 to 90% by mass, and still 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, the following tendency is exhibited: more sufficient stretchability is easily obtained, and the rubber component and the crosslinking component are sufficiently mixed. When the content of the rubber component (a) is 95% by mass or less, the following tendency is exhibited: the stretchable resin layer has particularly excellent properties in terms of adhesion, insulation reliability, and heat resistance. The content of the rubber component (a) in the stretchable resin layer may be within the above range based on the mass of the stretchable resin layer.

(B) The crosslinking component having an epoxy group is a component which crosslinks to form a crosslinked polymer at the time of curing reaction. (B) The crosslinking component having an epoxy group is not particularly limited as long as it has an epoxy group in a molecule, and may be, for example, a general epoxy resin. The epoxy resin may be any of monofunctional, difunctional and polyfunctional, and is not particularly limited, but a difunctional or polyfunctional epoxy resin may be used in order to obtain sufficient hardenability.

As the epoxy resin, there can be mentioned: bisphenol A type, bisphenol F type, phenol novolak type, naphthalene type, dicyclopentadiene type, cresol novolak type, and the like. The aliphatic chain-modified epoxy resin can impart flexibility. Examples of commercially available aliphatic chain-modified epoxy resins include: EXA-4816 manufactured by Diegon (DIC) GmbH. From the viewpoints of curability, low tackiness, and heat resistance, a phenol novolac type, a cresol novolac type, a naphthalene type, or a dicyclopentadiene type epoxy resin can be selected. The epoxy resins may be used alone or in combination of two or more.

By combining the rubber having a maleic anhydride group or a carboxyl group and the compound having an epoxy group (epoxy resin), particularly excellent effects can be obtained in terms of heat resistance and low moisture permeability of the stretchable resin layer, adhesiveness between the stretchable resin layer and the conductive layer, and low viscosity of the stretchable resin layer. If the heat resistance of the stretchable resin layer is improved, for example, deterioration of the stretchable resin layer in a heating step such as nitrogen reflow can be suppressed. If the stretchable resin layer has a low viscosity, the conductor substrate or the wiring substrate can be handled with good workability.

The resin composition may contain (B) a crosslinking component other than the crosslinking component having an epoxy group within a range not significantly impairing the effects of the present invention. From the viewpoint of more sufficiently reducing the dielectric loss tangent of the stretchable resin layer, the content of the other crosslinking component is preferably less than 10 parts by mass with respect to 100 parts by mass of the crosslinking component having an epoxy group (B).

(C) The ester-based curing agent is a compound which participates in the curing reaction itself, and can improve the heat resistance of the stretchable resin layer and reduce the dielectric loss tangent.

The ester-based curing agent is not particularly limited, but a compound having one or two or more highly reactive ester groups in one molecule, such as phenol esters, thiophenol esters, N-hydroxylamine esters, and esters of heterocyclic hydroxy compounds, can be preferably used from the viewpoint of more sufficiently obtaining the heat resistance-improving effect and the dielectric loss tangent-reducing effect. More specifically, examples of the ester-based hardener include "Aibitron (EPICLON) HPC 8000-65T", "Aibitron (EPICLON) HPC8000-L-65 MT", "Aibitron (EPICLON) HPC 8150-60T" (trade names manufactured by Diesen (DIC) Co., Ltd.). These may be used alone or in combination of two or more.

The ester-based curing agent is considered to react with the crosslinking component (B) as shown in the following formula (I) at the time of curing reaction. It is considered that no hydroxyl group is formed in the reaction between the ester-based curing agent (C) and the crosslinking component (B), and even if a side reaction occurs, a hydroxyl group is hardly formed, and as a result, a low dielectric loss tangent can be achieved.

[ solution 1]

In the formula, R¹、R²And R³Each independently represents a monovalent organic group, and may be a monovalent organic group having an aromatic ring in order to more fully obtain the effects of the present invention.

The resin composition may contain (C) a curing agent other than the ester-based curing agent within a range not significantly impairing the effects of the present invention. From the viewpoint of more sufficiently reducing the dielectric loss tangent of the stretchable resin layer, the content of the other curing agent is preferably less than 10 parts by mass with respect to 100 parts by mass of the ester-based curing agent (C).

The total content of the crosslinking component (B) and the ester-based curing agent (C) in the resin composition is preferably 5 to 40% by mass, more preferably 10 to 35% by mass, and still more preferably 15 to 30% 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 total content of the crosslinking component (B) and the ester-based curing agent (C) is 5% by mass or more, the following tendency is exhibited: more sufficient curing is easily obtained and the stretchable resin layer has particularly excellent properties in terms of adhesion, insulation reliability and heat resistance. When the total content of the crosslinking component (B) and the ester-based curing agent (C) is 40% by mass or less, the following tendency is exhibited: more sufficient stretchability is easily obtained, and the rubber component and the crosslinking component are sufficiently mixed.

In the resin composition, the content ratio of the (B) crosslinking component to the (C) ester-based curing agent is preferably 4: 5-5: 4, in the above range. When the content ratio is within the above range, the following tendency is exhibited: more sufficient curing is easily obtained and the stretchable resin layer has particularly excellent properties in terms of adhesion, insulation reliability and heat resistance.

The resin composition may further contain (D) a hardening accelerator. (D) The hardening accelerator is a compound that functions as a catalyst for the hardening reaction. (D) The hardening accelerator may be one selected from tertiary amines, imidazoles, organic acid metal salts, phosphorus compounds, Lewis acids, amine complex salts, and phosphines. Among them, imidazole is used from the viewpoint of storage stability and curability of the varnish of the resin composition. When the rubber component (a) contains a rubber partially modified with maleic anhydride, imidazole compatible with the rubber component (a) 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, (B) crosslinking component and (C) ester-based curing agent. When the content of the (D) hardening accelerator is 0.1 part by mass or more, more sufficient hardening tends to be easily obtained. When the content of the (D) hardening accelerator is 10 parts by mass or less, more sufficient heat resistance tends to be easily obtained. From the above viewpoint, the content of the (D) hardening accelerator may be 0.3 to 7 parts by mass, or 0.5 to 5 parts by mass.

The resin composition may further contain, in addition to the above components, an antioxidant, a yellowing inhibitor, an ultraviolet absorber, a visible light absorber, a colorant, a plasticizer, a stabilizer, a filler, a flame retardant, a leveling agent, and the like as necessary within a range not significantly impairing the effects of the present invention.

In particular, the resin composition may contain at least one anti-deterioration agent selected from the group consisting of an antioxidant, a heat stabilizer, a light stabilizer, and an anti-hydrolysis agent. The antioxidant suppresses deterioration caused by oxidation. In addition, the antioxidant imparts sufficient heat resistance to the stretchable resin layer at high temperatures. The heat stabilizer imparts stability at high temperature to the stretchable resin layer. Examples of light stabilizers include: an ultraviolet absorber for preventing deterioration due to ultraviolet rays, a light blocking agent for blocking light, and a matting agent having a matting function for stabilizing an organic material by receiving light energy absorbed by the organic material. The hydrolysis resistant agent suppresses deterioration caused by moisture. The deterioration resistant agent may be at least one selected from the group consisting of an antioxidant, a heat stabilizer, and an ultraviolet absorber. The deterioration inhibitor may be used alone or in combination of two or more kinds from the above-exemplified components. In order to obtain more excellent effects, two or more deterioration preventing agents may be used in combination.

The antioxidant may be, for example, one or more selected from the group consisting of a phenol-based antioxidant, an amine-based antioxidant, a sulfur-based antioxidant, and a phosphite-based antioxidant. In order to obtain more excellent effects, two or more antioxidants may be used in combination. Phenol-based antioxidants and sulfur-based antioxidants may also be used in combination.

The phenolic antioxidant may be a compound having a substituent having a large steric hindrance, such as a tert-butyl (t-butyl) group or a trimethylsilyl group, in an ortho position to the phenolic hydroxyl group. The phenol-based antioxidant is also called a hindered phenol-based antioxidant.

The phenol-based antioxidant may be selected from the group consisting of 2-tert-butyl-4-methoxyphenol, 3-tert-butyl-4-methoxyphenol, 2, 6-di-tert-butyl-4-ethylphenol, 2 '-methylene-bis (4-methyl-6-tert-butylphenol), 4' -thiobis- (3-methyl-6-tert-butylphenol), 4 '-butylidenebis (3-methyl-6-tert-butylphenol), 1, 3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, 1,3, 5-trimethyl-2, 4, 6-tris (3, 5-di-tert-butyl-4-hydroxybenzyl) benzene and tetrakis- [ methylene-3- (3' 5 '-di-tert-butyl-4' -hydroxyphenyl) propionate methane. The phenolic antioxidant may be a high-molecular phenolic antioxidant represented by 1,3, 5-trimethyl-2, 4, 6-tris (3, 5-di-tert-butyl-4-hydroxybenzyl) benzene and tetrakis- [ methylene-3- (3',5' -di-tert-butyl-4 ' -hydroxyphenyl) propionate ] methane.

The phosphite-based antioxidant may be selected from the group consisting of triphenyl phosphite, diphenylisodecyl phosphite, phenyldiisodecyl phosphite, 4' -butylidene-bis (3-methyl-6-tert-butylphenyl) -ditridecyl phosphite, neopentanetetraylbis (nonylphenyl) phosphite, neopentanetetraylbis (dinonylphenyl) phosphite, neopentanetetrayltris (nonylphenyl) phosphite, neopentanetetrayltris (dinonylphenyl) phosphite, 10- (2, 5-dihydroxyphenyl) -10H-9-oxa-10-phosphaphenanthrene-10-oxide, 2-methylenebis (4, 6-di-tert-butylphenyl) -2-ethylhexyl phosphite, and mixtures thereof, The one or more compounds selected from the group consisting of diisodecyl pentaerythritol diphosphite and tris (2, 4-di-tert-butylphenyl) phosphite may be tris (2, 4-di-tert-butylphenyl) phosphite.

Examples of the other antioxidants include hydroxylamine-based antioxidants represented by N-methyl-2-dimethylaminoacetiloximate (N-methyl-2-dimethyl amino acetic acid) and sulfur-based antioxidants represented by 3,3' -dilauryl 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. When the content of the antioxidant is 0.1% by mass or more, sufficient heat resistance of the stretchable resin layer can be easily obtained. If the content of the antioxidant is 20% by mass or less, bleeding and blooming (bloom) 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 in heating. In the case where two or more antioxidants are contained, the average value of the molecular weights of these may be in the above range.

Examples of the heat stabilizer (thermal deterioration inhibitor) include: metal soaps or inorganic acid salts such as combinations of zinc salts and barium salts of higher fatty acids, organotin compounds such as organotin maleate and organotin thiolate, and fullerenes (e.g., hydroxylated fullerenes).

Examples of the ultraviolet absorber include: benzophenone-based ultraviolet absorbers typified by 2, 4-dihydroxybenzophenone, benzotriazole-based ultraviolet absorbers typified by 2- (2' -hydroxy-5 ' -methylphenyl) benzotriazole, and cyanoacrylate-based ultraviolet absorbers typified by 2-ethylhexyl-2-cyano-3, 3' -diphenylacrylate.

Examples of the hydrolysis-resistant agent include: carbodiimide derivatives, epoxy compounds, isocyanate compounds, acid anhydrides, oxazoline compounds, and melamine compounds.

Other antidegradants include: hindered amine light stabilizer, ascorbic acid, propyl gallate, catechin, oxalic acid, malonic acid, and phosphite.

The stretchable resin layer can be produced, for example, by a method comprising: a resin varnish obtained by dissolving or dispersing (a) a rubber component, (B) a crosslinking component, and (C) an ester-based curing agent, and optionally other components in an organic solvent; and forming a resin varnish on the conductor foil or the carrier film by a method described later.

The organic solvent used herein is not particularly limited, and 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, γ -butyrolactone, and the like; carbonates such as ethylene carbonate and propylene carbonate; amides such as N, N-dimethylformamide, N-dimethylacetamide and N-methylpyrrolidone. Toluene or N, N-dimethylacetamide may also be used from the viewpoint of solubility and boiling point. These organic solvents may be used alone or in combination of two or more. The concentration of the solid content (other than the organic solvent) in the resin varnish may be 20 to 80% by mass.

The carrier film is not particularly limited, and examples thereof include: polyesters such as polyethylene terephthalate (PET), polybutylene terephthalate, and polyethylene naphthalate; polyolefins such as polyethylene and polypropylene; films such as polycarbonate, polyamide, polyimide, polyamideimide, polyetherimide, polyether sulfide, polyether sulfone, polyether ketone, polyphenylene ether, polyphenylene sulfide, polyarylate, polysulfone, and liquid crystal polymer. Among them, from the viewpoint of flexibility and toughness, a film 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, and may be 3 μm to 250 μm. When the thickness of the carrier film is 3 μm or more, the film strength is sufficient, and when the thickness of the carrier film is 250 μm or less, sufficient flexibility can be obtained. From the above viewpoint, the thickness may be 5 μm to 200 μm, or 7 μm to 150 μm. From the viewpoint of improving the releasability from the stretchable resin layer, a film obtained by subjecting a carrier film to a release treatment with a silicone compound, a fluorine-containing compound, or the like may be used as necessary.

If necessary, the protective film may be bonded to the stretchable resin layer, and may be a 3-layer laminated film including a conductor foil or a carrier film, the stretchable resin layer, and the protective film.

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

The thickness of the protective film may be suitably changed depending on the flexibility to be aimed at, and may be 10 μm to 250 μm. When the thickness is 10 μm or more, the film strength tends to be sufficient, and when the thickness is 250 μm or less, sufficient flexibility tends to be obtained. From the above viewpoint, the thickness may be 15 μm to 200 μm, or 20 μm to 150 μm.

[ method for manufacturing Wiring Board ]

The wiring board having a conductor foil according to one embodiment can be manufactured, for example, by a method including: a step of preparing a laminated sheet (conductor substrate) having a stretchable resin layer and a conductor foil laminated on the stretchable resin layer; a step of forming an etching resist on the conductor foil; a step of forming a resist pattern covering a part of the conductor foil by exposing an etching resist and developing the exposed etching resist; a step of removing the conductor foil of a portion not covered with the resist pattern; and a step of removing the resist pattern.

As a method for obtaining a laminated sheet (conductor substrate) having a stretchable resin layer and a conductor foil, any method can be used, and there are a method in which a varnish of a resin composition for forming a stretchable resin layer is applied to a conductor foil; and a method of laminating a conductor foil on a stretchable resin layer formed on a carrier film by a vacuum press, a laminator, or the like. The stretchable resin layer can be formed by heating the resin composition and performing a crosslinking reaction (curing reaction) of the crosslinking component.

The method of laminating the stretchable resin layer on the carrier film on the conductor foil may be any method, and a roll laminator, a vacuum press or the like may be used. From the viewpoint of production efficiency, the molding may be performed using a roll laminator or a vacuum laminator.

The thickness of the stretchable resin layer after drying is not particularly limited, but is usually 5 to 1000. mu.m. When the amount is within the above range, sufficient strength of the stretchable resin layer can be easily obtained, and the amount of residual solvent in the stretchable resin layer can be reduced because sufficient drying can be performed.

A laminated plate having conductor foils formed on both surfaces of the stretchable resin layer may be produced by laminating a conductor foil on the surface of the stretchable resin layer opposite to the conductor foil. By providing the conductor layers on both surfaces of the stretchable resin layer, warpage of the laminate during curing can be suppressed.

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

Examples of the etching resist used for etching include: futaike (photo) H-7025 (trade name, manufactured by Hitachi chemical Co., Ltd.), Futaike (photo) H-7030 (trade name, manufactured by Hitachi chemical Co., Ltd.), and X-87 (trade name, manufactured by solar control stock (TAIYO HOLDINGS) Co., Ltd.). After the formation of the wiring pattern, the etching resist is generally removed.

One embodiment of a method for manufacturing a wiring board having a conductor plating film includes: a step of forming a conductor plating film on the stretchable resin layer by electroless plating; a step of forming a plating resist on the conductor plating film; exposing the plating resist to light and developing the exposed plating resist to form a resist pattern covering a part of the stretchable resin layer; a step of further forming a conductor plating film by electroplating on the conductor plating film of the portion not covered with the resist pattern; a step of removing the resist pattern; and a step of removing a portion of the conductor plating film formed by electroless plating that is not covered by the conductor plating film formed by electroplating.

Another embodiment of the method for manufacturing a wiring board includes: a step of forming an etching resist on the conductor plating film formed on the stretchable resin layer; exposing the etching resist to light and developing the exposed etching resist to form a resist pattern covering a part of the stretchable resin layer; a step of removing the conductor plating film of a portion not covered with the resist pattern; and a step of removing the resist pattern.

Examples of the plating resist used as a mask for plating include: futache (photo) RY3325 (trade name, manufactured by Hitachi chemical Co., Ltd.), Futache (photo) RY-5319 (trade name, manufactured by Hitachi chemical Co., Ltd.), MA-830 (trade name, manufactured by Sun control Ltd.). Further, details regarding electroless plating and electroplating are as described above.

The stretchable element can be obtained by mounting various electronic devices on a wiring board.

[ examples ]

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 stretchable resin layer >

80 parts by mass (blending amount of nonvolatile component) of maleic anhydride-modified styrene-ethylene-butadiene rubber (trade name "FG 1924 GT" manufactured by Kanton (KRATON) Co., Ltd.) diluted with toluene and adjusted to 25% by mass of nonvolatile component as component (A), 11.1 parts by mass (blending amount of nonvolatile component) of dicyclopentadiene-type epoxy resin (trade name "Ailbaron (EPICLON) HP 7200H" manufactured by Di-Eden (DIC) Co., Ltd.) diluted with toluene and adjusted to 25% by mass of nonvolatile component as component (B), 8.9 parts by mass (blending amount of nonvolatile component) of dicyclopentadiene-type diphenol compound (trade name "HPC 8000-65T" manufactured by Di-Eden (DIC) Co., Ltd.) diluted with toluene and adjusted to 25% by mass of nonvolatile component as component (C), and, And 3 parts by mass of 1-benzyl-2-methylimidazole (trade name "1B 2 MZ" manufactured by four kingdom chemical company limited) as component (D) were mixed with stirring to obtain a resin varnish.

< production of laminated film >

A release-treated polyethylene terephthalate (PET) Film (trade name "Purex a 31" manufactured by Teijin DuPont Film gmbh) having a thickness of 25 μm) was prepared as a carrier Film. On the release-treated side of the PET film, the resin varnish was coated using a blade coater (trade name "SNC-350" manufactured by corning instruments incorporated). The coating film was dried by heating at 100 ℃ for 20 minutes in a dryer (trade name "MSO-80 TPS" manufactured by Bileaf science Co., Ltd.) to form a resin layer (stretchable resin layer before curing) having a thickness of 100 μm. A release-treated PET film, which was the same as the carrier film, was attached as a protective film to the formed resin layer in the direction in which the release-treated surface was on the resin layer side, to obtain a laminated film.

< production of conductor substrate >

The protective film of the laminated film was peeled off, and an electrolytic copper foil (trade name "F2-WS-12" manufactured by Kogawa electric industries, Ltd.) having a roughened surface with a surface roughness Ra of 1.5 μm was laminated on the exposed resin layer in such a direction that the roughened surface was the resin layer side. In this state, an electrolytic copper foil was laminated on the resin layer using a vacuum pressure type laminator (trade name "V130" manufactured by nikko-materials) corporation) under conditions of a pressure of 0.5MPa, a temperature of 90 ℃ and a pressing time of 60 seconds. Thereafter, the resultant was heated at 180 ℃ for 60 minutes in a dryer (trade name "MSO-80 TPS" manufactured by bicuspid science corporation), thereby obtaining a conductor substrate having a stretchable resin layer as a cured product of the resin layer and an electrolytic copper foil as a conductor layer.

(examples 2 to 6 and comparative examples 1 to 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, "HP 5000" is a novolac type epoxy resin (trade name "Ebilon (EPICLON) HP 5000" manufactured by Dieson (DIC) gmbh), "HPC 8000-L-65 MT" is an ester type hardener (low molecular weight grade of "Ebilon (EPICLON) HPC8000-L-65 MT" manufactured by Dieson (DIC) gmbh, HPC 8000-65T), and "HPC 8150-60T" is an ester type hardener (trade name "Ebilon (EPICLON) HPC 8150-60T" manufactured by Dieson (DIC) gmbh, a compound having a naphthalene skeleton).

[ measurement of tensile modulus of elasticity and elongation at Break ]

The laminated films obtained in examples and comparative examples were heated at 180 ℃ for 60 minutes to cure the resin layer, thereby forming a stretchable resin layer. The carrier film and the protective film were removed, and the stretchable resin layer was cut into a long piece having a length of 40mm and a width of 10mm to obtain a test piece. The tensile test of the test piece was performed using an autograph (autograph) (trade name "EZ-S" manufactured by shimadzu corporation) to obtain a stress-strain curve. The tensile modulus and elongation at break were determined from the obtained stress-strain curve. The tensile test was conducted under the conditions of an inter-chuck distance of 20mm and a tensile speed of 50 mm/min. The tensile modulus is determined from the slope of a stress-strain curve in the range of 0.5N to 1.0N. The strain at the point of time when the test piece broke was recorded as the elongation at break. The results are shown in table 1.

[ measurement of recovery Rate ]

In the same manner as the measurement of the tensile modulus of elasticity and the elongation at break, a test piece of a long stretchable resin layer having a length of 40mm and a width of 10mm was prepared. The test piece was elongated at a tensile rate of 100 mm/min until the strain became 20% using an automatic plotter (trade name "EZ-S" manufactured by Shimadzu corporation), and then the tensile test was performed again after releasing the stress and returning to the initial position. The recovery rate R is obtained by the following equation, where X represents the strain (displacement) applied in the first tensile test, and Y represents the difference between X and the position at which the load starts to be applied when the tensile test is performed again. 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 the measurement of the tensile modulus of elasticity and the elongation at break, a test piece of a stretchable resin layer having a size of 80mm × 80mm was prepared. Dk and Df were calculated by a cavity resonator method using the test piece. The measurement was performed under the conditions of an ambient temperature of 25 ℃ and a frequency of 10kHz using a vector type network analyzer E8364B (manufactured by Dekkit Technologies), CP531 (manufactured by Kanto electronic applications 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 to 2 were heated at 180 ℃ for 60 minutes to cure the resin layer and form a stretchable resin layer. After removing the carrier film and the protective film, the stretchable resin layer was subjected to a heat resistance test using a nitrogen reflow system ("TNV-EN" product name manufactured by ltd, manufactured by wamura ltd., ltd.) in which the step of heat-treating the stretchable resin layer using a temperature profile shown in fig. 3 according to the association of electronics industries and engineering/joint electronics industries joint center (IPC/JEDEC) J-STD-020 was repeated 10 times. After the heat resistance test, the tensile modulus, elongation at break and recovery of the stretchable resin layer were measured in the same manner as described above. The results are shown in tables 2 and 3 together with the measurement results before the heat resistance test.

[ measurement of Infrared Spectrum (IR) ]

The resin layer (the stretchable resin layer before curing) of the laminated film of comparative example 1, the stretchable resin layer after curing by heating at 180 ℃ for 60 minutes, and the stretchable resin layer after curing by heating at 180 ℃ for 60 minutes of the resin layers of the laminated films of examples 1 and 3 were subjected to a transmission method measurement of an infrared absorption spectrum using a fourier transform infrared spectrophotometer ("FTS 3000 MX" manufactured by Bio-Rad) after removing the carrier film and the protective film. Fig. 4 shows the infrared absorption spectra of the stretchable resin layer before and after curing in comparative example 1, and fig. 5 shows the infrared absorption spectra of the stretchable resin layers after curing in examples 1,3 and comparative example 1.

As shown in FIG. 4, 3400cm of the stretchable resin layer of comparative example 1 was observed to have stretching vibration attributed to hydroxyl groups which did not exist before curing after curing^-1The absorption peak in the vicinity generates hydroxyl groups by the curing reaction. As shown in fig. 5, it was confirmed that in the stretchable resin layers of examples 1 and 3, the absorption peak of stretching vibration attributed to the hydroxyl group was almost absent, and the generation of the hydroxyl group was suppressed.

[ production of Wiring Board and evaluation thereof ]

A wiring board 1 for testing was produced as shown in fig. 2, the wiring board 1 for testing having a stretchable resin layer 3 and a conductor foil (electrolytic copper foil) as a conductor layer 5 formed on the stretchable resin layer 3 and having a wave pattern. First, an etching resist (trade name "futokay (photo) RY-5325" manufactured by hitachi chemical corporation) was bonded to the conductor layer of the conductor substrate obtained in the example and the comparative example, in which the irregularities were formed on the surface of the stretchable resin layer, by using a roll laminator, and an optical tool (photo tool) having a wave pattern formed thereon was closely attached thereto. An EXM-1201 exposure machine manufactured by Onck (ORC) was used at 50mJ/cm²Is used to expose the etch resist. Then, the resist was subjected to spray development with a 1 mass% aqueous solution of sodium carbonate at 30 ℃ for 240 seconds to thereby remove the resistThe exposed portion is dissolved to form a resist pattern having a wave-shaped opening. Then, the copper foil is removed from the portion not covered with the resist pattern by an etching solution. Thereafter, the etching resist was removed by a stripping solution, and a wiring substrate 1 having a conductor layer 5 on the stretchable resin layer 3, in which a wiring pattern having a waveform with a wiring width of 50 μm and meandering in a predetermined direction X was formed, was obtained.

The obtained wiring board was subjected to tensile deformation in the X direction until the strain reached 10%, and the stretchable resin layer and the corrugated wiring pattern were observed when the board was returned to its original state. As a result, the wiring substrate of any of the examples and comparative examples did not break the stretchable resin layer and the wiring pattern even when stretched.

[ Table 1]

[ Table 2]

[ Table 3]

As can be seen from the results shown in table 1, the conductor substrates of examples 1 to 6 were confirmed to have excellent stretchability and a low dielectric loss tangent as compared with the conductor substrates of comparative examples 1 to 2. As can be seen from the results shown in tables 2 and 3, the conductor substrates of examples 1 to 6 were confirmed to maintain good stretchability and elastic modulus even after the heat resistance test.

[ industrial applicability ]

The conductor substrate and the wiring board obtained therefrom according to the present invention are expected to be used as, for example, a substrate for a wearable device.

[ description of symbols ]

1: wiring board

3: stretchable resin layer

5: conductor layer (conductor foil or conductor coating)

Claims

1. A conductor substrate is provided with:

a stretchable resin layer; and

a conductor foil provided on the stretchable resin layer,

the stretchable resin layer contains a cured product of a resin composition containing (A) a rubber component, (B) a crosslinking component having an epoxy group, and (C) an ester-based curing agent.

2. The conductor substrate according to claim 1, wherein the conductor foil has a coefficient of elasticity of 40GPa to 300 GPa.

3. A conductor substrate is provided with:

a stretchable resin layer; and

a conductor plating film provided on the stretchable resin layer,

4. The conductor substrate according to any one of claims 1 to 3, wherein a recovery rate after the stretchable resin layer is subjected to tensile deformation until the strain becomes 20% is 80% or more.

5. The conductor substrate according to any one of claims 1 to 4, wherein the (A) rubber component comprises at least one rubber selected from the group consisting of acrylic rubber, isoprene rubber, butyl rubber, styrene butadiene rubber, acrylonitrile butadiene rubber, silicone rubber, urethane rubber, chloroprene rubber, ethylene propylene rubber, fluorine rubber, vulcanized rubber, epichlorohydrin rubber, and chlorinated butyl rubber.

6. The conductor substrate according to any one of claims 1 to 5, wherein the (A) rubber component contains a rubber having a crosslinking group.

7. The conductor substrate according to claim 6, wherein the crosslinking group is at least one of an acid anhydride group or a carboxyl group.

8. The conductor substrate according to any one of claims 1 to 7, wherein the resin composition further contains (D) a hardening accelerator.

9. The conductor substrate according to any one of claims 1 to 8, wherein the content of the rubber component (A) is 60 to 95% by mass based on the total amount of the rubber component (A), the crosslinking component (B), and the ester-based curing agent (C).

10. The conductor substrate according to any one of claims 1 to 9, wherein the resin composition further contains an antioxidant.

11. A wiring substrate comprising the conductor substrate according to claim 1 or 2, the conductor foil forming a wiring pattern.

12. A wiring substrate comprising the conductor substrate according to claim 3, the conductor plating film forming a wiring pattern.

13. A telescopic element, comprising: the wiring substrate according to claim 11 or 12; and an electronic device mounted on the wiring board.

14. The conductor substrate according to claim 1 or 2, which is used to form a wiring substrate comprising a conductor substrate having a stretchable resin layer and a conductor foil provided on the stretchable resin layer, the conductor foil forming a wiring pattern.

15. The conductor substrate according to claim 3, which is used to form a wiring substrate comprising 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.

16. A method of manufacturing a wiring substrate, which manufactures the wiring substrate according to claim 11, the method comprising:

preparing a laminate sheet having a stretchable resin layer and a conductor foil laminated on the stretchable resin layer;

a step of forming an etching resist on the conductor foil;

exposing the etching resist to light and developing the exposed etching resist to form a resist pattern covering a part of the conductor foil;

a step of removing the conductor foil of a portion not covered with the resist pattern; and

and removing the resist pattern.

17. A method of manufacturing a wiring substrate, which manufactures the wiring substrate according to claim 12, the method comprising:

a step of forming a plating resist on the stretchable resin layer;

exposing the plating resist to light and developing the exposed plating resist to form a resist pattern covering a part of the stretchable resin layer;

a step of forming a conductor plating film by electroless plating on a surface of a portion of the stretchable resin layer not covered with the resist pattern; and

and removing the resist pattern.

18. A method of manufacturing a wiring substrate, which manufactures the wiring substrate according to claim 12, the method comprising:

a step of forming a conductor plating film on the stretchable resin layer by electroless plating;

a step of forming a plating resist on the conductor plating film;

a step of further forming a conductor plating film by electroplating on the conductor plating film of a portion not covered with the resist pattern;

a step of removing the resist pattern; and

a step of removing a portion of the conductor plating film formed by electroless plating that is not covered with the conductor plating film formed by electroplating.

19. A method of manufacturing a wiring substrate, which manufactures the wiring substrate according to claim 12, the method comprising:

a step of forming an etching resist on the conductor plating film formed on the stretchable resin layer;

exposing the etching resist to light and developing the exposed etching resist to form a resist pattern covering a part of the stretchable resin layer;

a step of removing the conductor plating film of a portion not covered with the resist pattern; and

and removing the resist pattern.