WO2018123732A1

WO2018123732A1 - Wiring board, method for producing same and stretchable device

Info

Publication number: WO2018123732A1
Application number: PCT/JP2017/045535
Authority: WO
Inventors: 剛史正木; 崇司川守; 薫平山田; タンイーシム; 禎宏小川
Original assignee: 日立化成株式会社
Priority date: 2016-12-26
Filing date: 2017-12-19
Publication date: 2018-07-05
Also published as: JPWO2018123732A1; JP7124711B2; TW201828374A; TWI753071B

Abstract

Disclosed is a wiring board 100 which comprises a stretchable resin layer 10, a conductor foil 20 that is arranged on the stretchable resin layer 10 and forms a wiring pattern; and a via hole 30 that is formed in the stretchable resin layer 10.

Description

WIRING BOARD, MANUFACTURING METHOD THEREOF, AND STRETCHABLE DEVICE

The present disclosure relates to a wiring board, a manufacturing method thereof, and a stretchable device.

In recent years, in the fields of wearable devices, healthcare-related devices, etc., there are demands for flexibility and stretchability that can be used along, for example, the curved surface or joints of the body, and that connection failure does not easily occur even when detached. In order to configure such a device, a member having high stretchability is required.

As a method of realizing a member having high stretchability, a chip or a semiconductor element is mounted on a flexible substrate based on polyimide resin having high folding resistance, and sealed with a stretchable resin composition. A method of stopping is reported (see Patent Document 1).

International Publication No. 2016/080346

As described in Patent Document 1, by providing the sealing material with elasticity, it became possible to realize a member having elasticity that was difficult with a conventional sealing material. On the other hand, since the base substrate does not have stretchability, it has been difficult to provide higher stretchability. Therefore, a wiring board having higher stretchability is required. Further, there is a demand for a wiring board that has higher stretchability and can be interlayer-connected at the time of lamination.

In such a situation, an object of the present disclosure is to provide a wiring board having high stretchability and capable of interlayer connection during lamination, a manufacturing method thereof, and a stretchable device.

As a result of diligent research to solve the above problems, the inventors of the present invention provide high stretchability by using a stretchable resin layer for the base substrate, and combines the stretchable resin layer and the conductive foil, It has been found that the above problem can be solved by providing a via hole in the stretchable resin layer.

That is, one aspect of the present disclosure provides the following invention.
[1] A wiring board having a stretchable resin layer, a conductor foil provided on the stretchable resin layer and forming a wiring pattern, and a via hole provided in the stretchable resin layer.
[2] The wiring board according to [1], wherein the conductor foil is a copper foil.
[3] The wiring board according to [1] or [2], wherein the via hole is formed by a laser or a drill.
[4] The wiring board according to any one of [1] to [3], wherein the via hole has a diameter of 10 to 500 μm.
[5] The wiring board according to any one of [1] to [4], further including a copper plating layer provided on an inner wall surface of the via hole.
[6] The land having a land portion provided around the via hole on the stretchable resin layer and connected to the copper plating layer, and a width of the land portion from an end surface of the via hole is 10 μm or more. The wiring board according to [5].
[7] The stretchable resin layer contains (A) a rubber component, and the rubber component is acrylic rubber, isoprene rubber, butyl rubber, styrene butadiene rubber, butadiene rubber, acrylonitrile butadiene rubber, silicone rubber, urethane rubber, chloroprene. The wiring board according to any one of the above [1] to [6], comprising at least one selected from the group consisting of rubber, ethylene propylene rubber, fluoro rubber, sulfurized rubber, epichlorohydrin rubber, and chlorinated butyl rubber.
[8] The wiring board according to any one of [1] to [7], wherein the stretchable resin layer includes (A) a cured product of a resin composition containing a rubber component.
[9] The wiring board according to [8], wherein the rubber component (A) includes a rubber having a crosslinking group.
[10] The wiring board according to [9], wherein the crosslinking group is at least one of an acid anhydride group or a carboxyl group.
[11] The resin composition further contains (B) a crosslinking component, and the crosslinking component is a (meth) acryl group, vinyl group, epoxy group, styryl group, amino group, isocyanurate group, ureido group, cyanate. The wiring board according to any one of the above [8] to [10], which is a compound having at least one reactive group selected from the group consisting of a group, an isocyanate group, and a mercapto group.
[12] The wiring board according to any one of [8] to [11], wherein the resin composition further contains at least one of (C) a curing agent or a curing accelerator.
[13] The wiring board according to any one of [7] to [12], wherein the rubber component content is 30 to 100% by mass with respect to 100% by mass of the stretchable resin layer.
[14] A step of preparing a laminate having a stretchable resin layer and a conductor foil laminated on the stretchable resin layer, a step of forming a via hole in the stretchable resin layer, and etching on the conductor foil Forming a resist; exposing the etching resist; developing the exposed etching resist to form a resist pattern covering a portion of the conductor foil; and a portion not covered by the resist pattern A method for producing a wiring board according to any one of the above [1] to [13], comprising the step of removing the conductive foil and the step of removing the resist pattern.
[15] The method according to [14], further comprising a step of forming a copper plating layer on the inner wall surface of the via hole after the step of forming a via hole in the stretchable resin layer.
[16] A stretchable device comprising the wiring board according to any one of [1] to [13] and an electronic element mounted on the wiring board.

According to the present disclosure, it is possible to provide a wiring board that has high stretchability and enables interlayer connection at the time of lamination, a manufacturing method thereof, and a stretchable device. Further, by using the wiring board provided by the present disclosure, it is possible to form a multilayer wiring board having elasticity and high density.

It is sectional drawing which shows one Embodiment of a wiring board. 6 is a stress-strain curve showing an example of measurement of recovery rate. It is a top view which shows one Embodiment of a wiring board. It is a graph which shows the temperature profile of a heat resistance test.

Hereinafter, preferred embodiments of the present disclosure will be described in detail with reference to the drawings. In the following description, the same or corresponding parts are denoted by the same reference numerals, and redundant description is omitted.

In the present specification, “(meth) acrylate” means at least one of acrylate and methacrylate corresponding thereto. The same applies to other similar expressions such as “(meth) acryl”. The materials exemplified below may be used alone or in combination of two or more unless otherwise specified. The numerical range indicated by using “to” indicates a range including the numerical values described before and after “to” as the minimum value and the maximum value, respectively. “A or B” only needs to include either A or B, and may include both.

In the numerical ranges described step by step in this specification, the upper limit value or lower limit value of a numerical range of a certain step may be replaced with the upper limit value or lower limit value of the numerical range of another step. Further, in the numerical ranges described in the present specification, the upper limit value or the lower limit value of the numerical range may be replaced with the values shown in the examples (reference examples).

A wiring board according to an embodiment includes a stretchable resin layer, a conductor foil provided on the stretchable resin layer and forming a wiring pattern, and a via hole provided in the stretchable resin layer.

FIG. 1 is a cross-sectional view showing an embodiment of a wiring board. A wiring board 100 shown in FIG. 1 is formed on a stretchable resin layer 10 as a base material, a conductive foil 20 provided on the stretchable resin layer 10 and forming a wiring pattern, and the stretchable resin layer 10. Via hole 30, electroless copper plating layer 40 provided on the inner wall surface of via hole 30, and land portion 50 provided around via hole 30 on stretchable resin layer 10 and connected to electroless copper plating layer 40. And having.

The wiring board according to the present embodiment uses a base material formed from the stretchable resin layer 10, and thus has excellent stretchability compared to the case where a conventional substrate is used, and does not form the via hole 30. By forming the electroless copper plating layer 40 by performing electrolytic copper plating, interlayer connection is possible, and a wiring design equivalent to a conventional wiring board is possible. Thereby, it is possible to manufacture a multilayer wiring board having excellent stretchability and capable of high-density wiring.

The diameter (hole diameter) D of the opening before forming the electroless copper plating layer 40 of the via hole 30 is preferably 10 μm or more, and more preferably 40 μm or more from the viewpoint of the depositability of the electroless copper plating. From the relationship between via processability and wiring density, it is preferably 500 μm or less, and more preferably 250 μm or less.

The thickness of the electroless copper plating layer 40 is not particularly limited, but is preferably 0.1 to 1.5 μm, and preferably 0.3 to 1.0 μm from the viewpoint of adhesion with the stretchable resin layer 10. It is more preferable.

Further, for the purpose of increasing the conductor thickness, electrolytic copper plating may be further performed on the electroless copper plating layer 40 to form an electrolytic copper plating layer. The thickness of the electrolytic copper plating layer is not particularly limited, but is preferably 1 to 100 μm, more preferably 10 to 50 μm from the viewpoint of via hole connection reliability.

The width W from the end face of the via hole 30 of the land part 50 is preferably 10 μm or more, and more preferably 100 μm or more in order to maintain the interlayer connection by the electroless copper plating layer 40 when the substrate is stretched.

The land portion 50 is a conductor layer provided around the via hole 30 and is preferably formed concentrically with the via hole 30 on the surface of the stretchable resin layer 10. The land portion 50 may be made of the same material as that of the conductor foil 20 described later. The diameter of the land portion 50 on the surface of the stretchable resin layer 10 is adjusted so that the width W of the land portion 50 falls within the above range.

The conductor foil 20 may form a corrugated wiring pattern that meanders along the direction from the near side to the far side in FIG. In addition, there is no restriction | limiting in particular in the shape of the wiring pattern of the conductor foil 20, and it can determine suitably.

The elastic modulus of the conductor foil 20 may be 40 to 300 GPa. When the elastic modulus of the conductor foil is 40 to 300 GPa, the conductor foil tends not to break due to the elongation of the wiring board. From the same viewpoint, the elastic modulus of the conductor foil may be 50 GPa or more or 280 GPa or more, or 60 GPa or less, or 250 GPa or less. The elastic modulus of the conductor foil here can be a value measured by a resonance method.

The conductor foil can be a metal foil. As metal foil, 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, white 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, hastelloy foil and the like. From the viewpoint of an appropriate elastic modulus and the like, the conductor foil is preferably selected from copper foil, gold foil, nickel foil, and iron foil. From the viewpoint of wiring formability, it is preferable to use a copper foil.

There is no restriction | limiting in particular as copper foil, For example, the electrolytic copper foil and rolled copper foil generally used for a copper clad laminated board, a flexible wiring board, etc. can be used. Commercially available electrolytic copper foils include, for example, F0-WS-18 (trade name, manufactured by Furukawa Electric Co., Ltd.), NC-WS-20 (trade name, manufactured by Furukawa Electric Co., Ltd.), YGP-12 (Japan Electrolytic ( (Trade name), GTS-18 (trade name, manufactured by Furukawa Electric Co., Ltd.), and F2-WS-12 (trade name, manufactured by Furukawa Electric Co., Ltd.). Examples of rolled copper foil include TPC foil (manufactured by JX Metals Co., Ltd., trade name), HA foil (manufactured by JX Metals Co., Ltd., trade name), and HA-V2 foil (manufactured by JX Metals Co., Ltd., trade name). , And C1100R (trade name, manufactured by Sumitomo Mitsui Metal Mining Co., Ltd.). From the viewpoint of further improving the adhesiveness with the stretchable resin layer, it is preferable to use a copper foil that has been subjected to a roughening treatment. Moreover, it is preferable to use a rolled copper foil from the viewpoint of folding resistance and stretchability.

The stretchable resin layer 10 can have stretchability such that the recovery rate after tensile deformation to 20% strain is 80% or more. This recovery rate is calculated | required in the tension test using the measurement sample of an elastic resin layer. The strain (displacement amount) applied in the first tensile test is X, and then the difference between X and the position at which the load starts when the tensile test is performed again after returning to the initial position is defined as Y: %) = R calculated as Y / X × 100 is defined as the recovery rate. The recovery rate can be measured with X as 20%. FIG. 2 is a stress-strain curve showing an example of measuring the recovery rate. If the recovery rate is 80% or more, it can withstand repeated use, so the recovery rate is more preferably 85% or more, and still more preferably 90% or more.

The elastic modulus of the stretchable resin layer is preferably from 0.1 MPa to 1000 MPa. 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. In this respect, the elastic modulus is more preferably 0.3 MPa or more and 100 MPa or less, and further preferably 0.5 MPa or more and 50 MPa or less.

The elongation at break of the stretchable resin layer is preferably 100% or more. When the elongation at break is 100% or more, sufficient stretchability tends to be obtained. In this respect, the elongation at break is more preferably 150% or more, further preferably 200% or more, particularly preferably 300% or more, and extremely preferably 500% or more. The upper limit of the elongation at break is not particularly limited, but is usually about 1000% or less.

The stretchable resin layer can contain (A) a rubber component. Mainly, the rubber component easily imparts stretchability to the stretchable resin layer. The rubber component content may be 30 to 100% by mass with respect to 100% by mass of the stretchable resin layer.

Rubber components include, 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, fluorine rubber, sulfurized rubber, epichlorohydrin rubber, and chlorinated rubber. At least one of butyl rubber can be included. From the viewpoint of protecting the wiring from damage due to moisture absorption or the like, it is preferable that the gas permeability of the rubber component is low. From this viewpoint, the rubber component may be at least one selected from styrene butadiene rubber, butadiene rubber, and butyl rubber.

Examples of commercially available acrylic rubber include “Nipol AR Series” manufactured by Nippon Zeon Co., Ltd. and “Clarity Series” manufactured by Kuraray Co., Ltd.

Examples of commercially available isoprene rubber include “Nipol IR series” manufactured by Nippon Zeon Co., Ltd.

Examples of commercially available butyl rubber include “BUTYL Series” manufactured by JSR Corporation.

Examples of commercially available styrene butadiene rubber include “Dynalon SEBS Series”, “Dynalon HSBR Series” manufactured by JSR Corporation, “Clayton D Polymer Series” manufactured by Kraton Polymer Japan Co., Ltd., and Aron Kasei Co., Ltd. "AR series".

Examples of commercially available butadiene rubber include “Nipol BR series” manufactured by Nippon Zeon Co., Ltd.

Examples of commercially available acrylonitrile butadiene rubber include “JSR NBR series” manufactured by JSR Corporation.

Examples of commercially available silicone rubber include “KMP series” manufactured by Shin-Etsu Silicone Co., Ltd.

Examples of commercially available ethylene propylene rubber include “JSR EP Series” manufactured by JSR Corporation.

Examples of commercially available fluoro rubber products include “DAIEL Series” manufactured by Daikin Corporation.

As a commercial product of epichlorohydrin rubber, for example, “Hydrin series” manufactured by Nippon Zeon Co., Ltd. may be mentioned.

The rubber component can also be produced by synthesis. For example, acrylic rubber can be obtained by reacting (meth) acrylic acid, (meth) acrylic acid ester, aromatic vinyl compound, vinyl cyanide compound and the like.

The rubber component may contain a rubber having a crosslinking group. By using the rubber having a crosslinking group, the heat resistance of the stretchable resin layer tends to be improved. The cross-linking group may be a reactive group capable of causing a reaction to cross-link the molecular chain of the rubber component. Examples thereof include a reactive group, an acid anhydride group, an amino group, a hydroxyl group, an epoxy group, and a carboxyl group that the (B) crosslinking component described later has.

The rubber component may contain a rubber having at least one crosslinking group out of an acid anhydride group or a carboxyl group. Examples of rubbers having acid anhydride groups include rubbers that are partially modified with maleic anhydride. Rubber partially modified with maleic anhydride is a polymer containing structural units derived from maleic anhydride. As a commercial product of rubber partially modified with maleic anhydride, for example, there is a styrene elastomer “Tufprene 912” manufactured by Asahi Kasei Corporation.

The rubber partially modified with maleic anhydride may be a hydrogenated styrene elastomer partially modified with maleic anhydride. The hydrogenated styrene-based elastomer can be expected to have an effect of improving weather resistance. The hydrogenated styrene-based elastomer is an elastomer obtained by adding hydrogen to an unsaturated double bond of a styrene-based elastomer having a soft segment including an unsaturated double bond. Examples of commercially available hydrogenated styrene elastomers partially modified with maleic anhydride include “FG1901” and “FG1924” manufactured by Kraton Polymer Japan Co., Ltd., and “Tuftec M1911” manufactured by Asahi Kasei Corporation. , “Tuff Tech M1913” and “Tuff Tech M1943”.

The weight average molecular weight of the 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 means a standard polystyrene conversion value determined by gel permeation chromatography (GPC).

The stretchable resin layer may be a cured product of a resin composition containing (A) a rubber component. In this case, a curable resin composition is used as the resin composition for forming the stretchable resin layer. This curable resin composition may further contain, for example, (B) a crosslinking component. That is, the stretchable resin layer may further contain (B) a crosslinked polymer of a crosslinking component. The crosslinking component is, for example, selected from the group consisting of (meth) acrylic group, vinyl group, epoxy group, styryl group, amino group, isocyanurate group, ureido group, cyanate group, isocyanate group, mercapto group, hydroxyl group, and carboxyl group. It may be a compound having at least one kind of reactive group, and a cured product containing a crosslinked polymer can be formed by the reaction of these reactive groups. From the viewpoint of improving the heat resistance of the stretchable resin layer, the crosslinking component may be a compound having a reactive group selected from an epoxy group, an amino group, a hydroxyl group, and a carboxyl group. These compounds can be used alone or in combination of two or more.

(A) (meth) acrylate compound is mentioned as a compound which has a (meth) acryl group. The (meth) acrylate compound may be monofunctional, bifunctional or polyfunctional, and is not particularly limited, but bifunctional or polyfunctional (meth) acrylate is preferred in order to obtain sufficient curability.

Examples of the monofunctional (meth) acrylate include methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, tert-butyl (meth) acrylate, butoxyethyl (meth) acrylate, Isoamyl (meth) acrylate, hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, heptyl (meth) acrylate, octylheptyl (meth) acrylate, nonyl (meth) acrylate, decyl (meth) acrylate, undecyl (meth) acrylate , Lauryl (meth) acrylate, tridecyl (meth) acrylate, tetradecyl (meth) acrylate, pentadecyl (meth) acrylate, hexadecyl (meth) acrylate, stearyl (Meth) acrylate, behenyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-chloro-2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate , Methoxypolyethyleneglycol (meth) acrylate, ethoxypolyethyleneglycol (meth) acrylate, methoxypolypropyleneglycol (meth) acrylate, ethoxypolypropyleneglycol (meth) acrylate, mono (2- (meth) acryloyloxyethyl) succinate, etc. (Meth) acrylate; cyclopentyl (meth) acrylate, cyclohexyl (meth) acrylate, cyclopentyl (meth) acrylate, dicyclopentanyl (me ) Acrylate, dicyclopentenyl (meth) acrylate, isobornyl (meth) acrylate, mono (2- (meth) acryloyloxyethyl) tetrahydrophthalate, mono (2- (meth) acryloyloxyethyl) hexahydrophthalate, etc. Cyclic (meth) acrylate; benzyl (meth) acrylate, phenyl (meth) acrylate, o-biphenyl (meth) acrylate, 1-naphthyl (meth) acrylate, 2-naphthyl (meth) acrylate, phenoxyethyl (meth) acrylate, p-cumylphenoxyethyl (meth) acrylate, o-phenylphenoxyethyl (meth) acrylate, 1-naphthoxyethyl (meth) acrylate, 2-naphthoxyethyl (meth) acrylate, phenoxypolyethyleneglycol (Meth) acrylate, nonylphenoxypolyethylene glycol (meth) acrylate, phenoxypolypropylene glycol (meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, 2-hydroxy-3- (o-phenylphenoxy) propyl ( Aromatic (meth) acrylates such as (meth) acrylate, 2-hydroxy-3- (1-naphthoxy) propyl (meth) acrylate, 2-hydroxy-3- (2-naphthoxy) propyl (meth) acrylate; Heterocyclic (meth) acrylates such as furyl (meth) acrylate, N- (meth) acryloyloxyethyl hexahydrophthalimide, 2- (meth) acryloyloxyethyl-N-carbazole, and their caprolactone modified And the like. Among these, the aliphatic (meth) acrylate and the aromatic (meth) acrylate are preferable from the viewpoint of compatibility with the styrene-based elastomer, transparency, and heat resistance.

Examples of the bifunctional (meth) acrylate include ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, and polyethylene glycol di (meth) acrylate. , Propylene glycol di (meth) acrylate, dipropylene glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, tetrapropylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, ethoxylated polypropylene glycol di ( (Meth) acrylate, 1,3-butanediol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, neopent Glycol di (meth) acrylate, 3-methyl-1,5-pentanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, 2-butyl-2-ethyl-1,3-propanediol di (Meth) acrylate, 1,9-nonanediol di (meth) acrylate, 1,10-decanediol di (meth) acrylate, glycerin di (meth) acrylate, tricyclodecane dimethanol (meth) acrylate, ethoxylated 2- Aliphatic (meth) acrylates such as methyl-1,3-propanediol di (meth) acrylate; cyclohexanedimethanol (meth) acrylate, ethoxylated cyclohexanedimethanol (meth) acrylate, propoxylated cyclohexanedimethanol (meth) acrylate, Etoki Propoxylated cyclohexanedimethanol (meth) acrylate, tricyclodecane dimethanol (meth) acrylate, ethoxylated tricyclodecane dimethanol (meth) acrylate, propoxylated tricyclodecane dimethanol (meth) acrylate, ethoxylated propoxylated tri Cyclodecane dimethanol (meth) acrylate, ethoxylated hydrogenated bisphenol A di (meth) acrylate, propoxylated hydrogenated bisphenol A di (meth) acrylate, ethoxylated propoxylated hydrogenated bisphenol A di (meth) acrylate, ethoxylated water Alicyclic such as bisphenol F di (meth) acrylate, propoxylated hydrogenated bisphenol F di (meth) acrylate, ethoxylated propoxy hydrogenated bisphenol F di (meth) acrylate (Meth) acrylate; ethoxylated bisphenol A di (meth) acrylate, propoxylated bisphenol A di (meth) acrylate, ethoxylated propoxylated bisphenol A di (meth) acrylate, ethoxylated bisphenol F di (meth) acrylate, propoxylated bisphenol F di (meth) acrylate, ethoxylated propoxylated bisphenol F di (meth) acrylate, ethoxylated bisphenol AF di (meth) acrylate, propoxylated bisphenol AF di (meth) acrylate, ethoxylated propoxylated bisphenol AF di (meth) acrylate , Ethoxylated fluorene-type di (meth) acrylate, propoxylated fluorene-type di (meth) acrylate, ethoxylated propoxylated fluorene-type di (meth) acrylate Aromatic (meth) acrylates such as ethoxylated isocyanuric acid di (meth) acrylate, propoxylated isocyanuric acid di (meth) acrylate, ethoxylated propoxylated isocyanuric acid di (meth) acrylate, etc. These modified caprolactones; aliphatic epoxy (meth) acrylates such as neopentyl glycol type epoxy (meth) acrylate; cyclohexanedimethanol type epoxy (meth) acrylate, hydrogenated bisphenol A type epoxy (meth) acrylate, hydrogenated bisphenol Cycloaliphatic epoxy (meth) acrylates such as F type epoxy (meth) acrylate; and resorcinol type epoxy (meth) acrylate, bisphenol A type epoxy (meth) acrylate, bisphenol F type e Carboxymethyl (meth) acrylate, bisphenol AF type epoxy (meth) acrylates, and aromatic epoxy (meth) acrylates such as fluorene epoxy (meth) acrylate. Among these, the aliphatic (meth) acrylate and the aromatic (meth) acrylate are preferable from the viewpoint of compatibility with the styrene-based elastomer, transparency, and heat resistance.

Examples of the trifunctional or higher polyfunctional (meth) acrylate include trimethylolpropane tri (meth) acrylate, ethoxylated trimethylolpropane tri (meth) acrylate, propoxylated trimethylolpropane tri (meth) acrylate, and ethoxylated propoxylated tri Methylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, ethoxylated pentaerythritol tri (meth) acrylate, propoxylated pentaerythritol tri (meth) acrylate, ethoxylated propoxylated pentaerythritol tri (meth) acrylate, pentaerythritol Tetra (meth) acrylate, ethoxylated pentaerythritol tetra (meth) acrylate, propoxylated pentaerythritol tetra ( ) Aliphatic (meth) acrylates such as acrylate, ethoxylated propoxylated pentaerythritol tetra (meth) acrylate, ditrimethylolpropane tetraacrylate, dipentaerythritol hexa (meth) acrylate; ethoxylated isocyanuric acid tri (meth) acrylate, propoxy Heterocyclic (meth) acrylates such as triisocyanuric acid tri (meth) acrylate and ethoxylated propoxylated isocyanuric acid tri (meth) acrylate; modified caprolactone thereof; and phenol novolac type epoxy (meth) acrylate and cresol novolac type epoxy Aromatic epoxy (meth) acrylates such as (meth) acrylates may be mentioned. Among these, the aliphatic (meth) acrylate and the aromatic (meth) acrylate are preferable from the viewpoint of compatibility with the styrene-based elastomer, transparency, and heat resistance.

By combining a rubber having a maleic anhydride group or a carboxyl group and a compound having an epoxy group (epoxy resin), heat resistance and low moisture permeability of the stretchable resin layer, adhesion between the stretchable resin layer and the conductive layer, And the especially outstanding effect is acquired at the point of the low tack of the resin layer after hardening. When the heat resistance of the stretchable resin layer is improved, deterioration of the stretchable resin layer in a heating process such as nitrogen reflow can be suppressed. When the cured resin layer has a low tack, the conductor substrate or the wiring substrate can be handled with good workability.

The compound containing 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 is preferable in order to obtain sufficient curability.

Examples of the epoxy resin include bisphenol A type, bisphenol F type, phenol novolac type, naphthalene type, dicyclopentadiene type, and cresol novolac type. An epoxy resin modified with a fatty chain is preferred because flexibility can be imparted. Examples of commercially available fatty chain-modified epoxy resins include EXA-4816 manufactured by DIC Corporation. From the viewpoints of curability, low tack, and heat resistance, a phenol novolac type, a cresol novolac type, a naphthalene type, and a dicyclopentadiene type may be selected. These epoxy resins can be used alone or in combination of two or more.

The content of the crosslinked polymer formed from the crosslinking component is preferably 10 to 50% by mass based on the mass of the stretchable resin layer. If the content of the cross-linked polymer formed from the cross-linking component is in the above range, the adhesion with the conductor foil tends to be improved while maintaining the properties of the stretchable resin layer. From the above viewpoint, the content of the crosslinked polymer formed from the crosslinking component is more preferably 15 to 40% by mass. The content of the crosslinking component in the resin composition for forming the stretchable resin layer may be within these ranges.

The stretchable resin layer or the resin composition used to form it can further contain an additive as the component (C). (C) The additive may be at least one of a curing agent or a curing accelerator. The curing agent is a compound that itself participates in the curing reaction, and the curing accelerator is a compound that functions as a catalyst for the curing reaction. A compound having both functions of a curing agent and a curing accelerator can also be used. The curing agent may be a polymerization initiator. These can be appropriately selected according to other components contained in the resin composition. For example, if it is a resin composition containing a (meth) acrylate compound, a polymerization initiator may be added. The polymerization initiator is not particularly limited as long as it initiates polymerization by heating or irradiation with ultraviolet rays or the like. For example, a thermal radical polymerization initiator or a photo radical polymerization initiator can be used. If it is a thermal radical initiator, it is preferable at the point that reaction of a resin composition advances uniformly. If it is a photo radical initiator, since normal temperature hardening is possible, it is preferable at the point which prevents the deterioration by the heat | fever of a device, and the point which can suppress the curvature of a stretchable resin layer.

Examples of the thermal radical polymerization initiator include ketone peroxides such as methyl ethyl ketone peroxide, cyclohexanone peroxide, and methylcyclohexanone peroxide; 1,1-bis (t-butylperoxy) cyclohexane, 1,1-bis (t- Butylperoxy) -2-methylcyclohexane, 1,1-bis (t-butylperoxy) -3,3,5-trimethylcyclohexane, 1,1-bis (t-hexylperoxy) cyclohexane, 1,1- Peroxyketals such as bis (t-hexylperoxy) -3,3,5-trimethylcyclohexane; hydroperoxides such as p-menthane hydroperoxide; α, α′-bis (t-butylperoxy) diisopropylbenzene , Dicumyl peroxide, t-butyl cumyl peroxy Dialkyl peroxides such as sid and di-t-butyl peroxide; diacyl peroxides such as octanoyl peroxide, lauroyl peroxide, stearyl peroxide and benzoyl peroxide; bis (4-t-butylcyclohexyl) peroxydicarbonate Peroxycarbonates such as di-2-ethoxyethyl peroxydicarbonate, di-2-ethylhexyl peroxydicarbonate, di-3-methoxybutyl peroxycarbonate; t-butyl peroxypivalate, t-hexyl peroxy Pivalate, 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate, 2,5-dimethyl-2,5-bis (2-ethylhexanoylperoxy) hexane, t-hexylper Oxy-2-ethylhexa Ate, t-butylperoxy-2-ethylhexanoate, t-butylperoxyisobutyrate, t-hexylperoxyisopropyl monocarbonate, t-butylperoxy-3,5,5-trimethylhexanoate, t-butyl peroxylaurate, t-butyl peroxyisopropyl monocarbonate, t-butyl peroxy-2-ethylhexyl monocarbonate, t-butyl peroxybenzoate, t-hexyl peroxybenzoate, 2,5-dimethyl-2 , 5-bis (benzoylperoxy) hexane, peroxyesters such as t-butylperoxyacetate; and 2,2′-azobisisobutyronitrile, 2,2′-azobis (2,4-dimethylvaleronitrile) ), 2,2′-azobis (4-methoxy- '- dimethyl valeronitrile) azo compounds, and the like. Among these, the diacyl peroxide, the peroxyester, and the azo compound are preferable from the viewpoints of curability, transparency, and heat resistance.

Examples of radical photopolymerization initiators include benzoin ketals such as 2,2-dimethoxy-1,2-diphenylethane-1-one; 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenylpropane- Α-hydroxy ketones such as 1-one, 1- [4- (2-hydroxyethoxy) phenyl] -2-hydroxy-2-methyl-1-propan-1-one; 2-benzyl-2-dimethylamino-1 Α-amino ketones such as-(4-morpholinophenyl) -butan-1-one, 1,2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropan-1-one; Oxime esters such as 4- (phenylthio) phenyl] -1,2-octadion-2- (benzoyl) oxime; bis (2,4,6-tri Phosphine oxides such as methylbenzoyl) phenylphosphine oxide, bis (2,6-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide, 2,4,6-trimethylbenzoyldiphenylphosphine oxide; 2- (o-chlorophenyl) ) -4,5-diphenylimidazole dimer, 2- (o-chlorophenyl) -4,5-di (methoxyphenyl) imidazole dimer, 2- (o-fluorophenyl) -4,5-diphenylimidazole dimer 2,4,5-triaryl such as 2-mer, 2- (o-methoxyphenyl) -4,5-diphenylimidazole dimer, 2- (p-methoxyphenyl) -4,5-diphenylimidazole dimer Imidazole dimer; benzophenone, N, N, N ′, N′-tetramethyl-4, Benzophenone compounds such as '-diaminobenzophenone, N, N, N', N'-tetraethyl-4,4'-diaminobenzophenone, 4-methoxy-4'-dimethylaminobenzophenone; 2-ethylanthraquinone, phenanthrenequinone, 2- tert-butylanthraquinone, octamethylanthraquinone, 1,2-benzanthraquinone, 2,3-benzanthraquinone, 2-phenylanthraquinone, 2,3-diphenylanthraquinone, 1-chloroanthraquinone, 2-methylanthraquinone, 1,4-naphthoquinone Quinone compounds such as 9,10-phenanthraquinone, 2-methyl-1,4-naphthoquinone, 2,3-dimethylanthraquinone; benzoin methyl ether, benzoin ethyl ether, benzoin phenyl ether Benzoin ethers such as benzoin; benzoin compounds such as benzoin, methylbenzoin and ethylbenzoin; benzyl compounds such as benzyldimethyl ketal; acridines such as 9-phenylacridine and 1,7-bis (9,9'-acridinylheptane) Compounds; N-phenylglycine; and coumarin.

In the 2,4,5-triarylimidazole dimer, the substituents of the aryl groups at the two triarylimidazole sites may give the same and symmetrical compounds, or differently give asymmetrical compounds. . Like a combination of diethylthioxanthone and dimethylaminobenzoic acid, a thioxanthone compound and a tertiary amine may be combined.

Of these, the α-hydroxy ketone and the phosphine oxide are preferable from the viewpoints of curability, transparency, and heat resistance. These thermal and photo radical polymerization initiators can be used alone or in combination of two or more. Furthermore, it can also be used in combination with a suitable sensitizer.

When the curable resin composition for forming the stretchable resin layer contains (A) a rubber component, (B) a crosslinking component, and a curing agent as the (C) component, it contains a curing agent (or a polymerization initiator). The amount is preferably 0.1 to 10 parts by mass with respect to 100 parts by mass of the total amount of the rubber component and the crosslinking component. When the content of the curing agent (or polymerization initiator) is 0.1 parts by mass or more, sufficient curing tends to be easily obtained. When the content of the curing agent (or polymerization initiator) is 10 parts by mass or less, sufficient light transmittance tends to be easily obtained. From the above viewpoint, the content of the curing agent (or polymerization initiator) is more preferably 0.3 to 7 parts by mass, and further preferably 0.5 to 5 parts by mass.

The curing agent may contain at least one selected from the group consisting of aliphatic polyamines, polyaminoamides, polymercaptans, aromatic polyamines, acid anhydrides, carboxylic acids, phenol novolac resins, ester resins, and dicyandiamide. These curing agents can be used in combination with, for example, a compound having an epoxy group (epoxy resin).

A curing accelerator selected from tertiary amine, imidazole, acid anhydride, and phosphine may be added as a component (C) to the resin composition containing an epoxy resin. From the viewpoint of storage stability and curability of the varnish, it is preferable to use imidazole. When the rubber component includes a rubber partially modified with maleic anhydride, an imidazole compatible with the rubber may be selected.

When the resin composition for forming the stretchable resin layer contains (A) a rubber component and (B) a crosslinking component, the content of imidazole is 100 parts by mass with respect to the total amount of the rubber component and the crosslinking component. It may be 0.1 to 10 parts by mass. When the content of imidazole is 0.1 parts by mass or more, sufficient curing tends to be easily obtained. When the content of imidazole is 10 parts by mass or less, sufficient heat resistance tends to be obtained. From the above viewpoint, the imidazole content may be 0.3 to 7 parts by mass, or 0.5 to 5 parts by mass.

When the resin composition for forming the stretchable resin layer contains (A) a rubber component, (B) a crosslinking component, and (C) an additive, the content of the rubber component is (A) the rubber component, (B It may be 30-98% by weight, 50-97% by weight, or 60-95% by weight, based on the total amount of)) crosslinking component and (C) additive. When the content of the rubber component is 30% by mass or more, sufficient stretchability is easily obtained. When the content of the rubber component is 98% by mass or less, the stretchable resin layer tends to have particularly excellent characteristics in terms of adhesion, insulation reliability, and heat resistance.

In addition to the above components, the stretchable resin layer or the resin composition for forming the resin layer may contain an antioxidant, a yellowing inhibitor, an ultraviolet absorber, a visible light absorber, a colorant, a plasticizer, if necessary. An agent, a stabilizer, a filler, a flame retardant, a leveling agent, and the like may be further included as long as the effects of the present disclosure are not significantly impaired.

The stretchable resin layer is obtained by, for example, dissolving or dispersing a coupling agent, a rubber component and, if necessary, other components in an organic solvent to obtain a resin varnish, and the resin varnish on a conductor foil or carrier film by a method described later. It can manufacture by the method including forming into a film.

The organic solvent used here 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; acetone, methyl ethyl ketone, Ketones such as methyl isobutyl ketone, cyclohexanone, 4-hydroxy-4-methyl-2-pentanone; esters such as methyl acetate, ethyl acetate, butyl acetate, methyl lactate, ethyl lactate, γ-butyrolactone; ethylene carbonate, propylene carbonate, etc. And carbonates; and amides such as N, N-dimethylformamide, N, N-dimethylacetamide, N-methylpyrrolidone and the like. These organic solvents can be used alone or in combination of two or more. From the viewpoint of solubility and boiling point, toluene or N, N-dimethylacetamide may be used. The concentration of solids (components other than organic solvents) in the resin varnish is usually preferably 20 to 80% by mass.

The material of the carrier film is not particularly limited, but for example, polyesters such as polyethylene terephthalate (PET), polybutylene terephthalate, polyethylene naphthalate; polyolefins such as polyethylene and polypropylene; polycarbonates, polyamides, polyimides, polyamideimides, polyetherimides , Polyether sulfide, polyether sulfone, polyether ketone, polyphenylene ether, polyphenylene sulfide, polyarylate, polysulfone and liquid crystal polymer. Among these, from the viewpoint of flexibility and toughness, a polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polypropylene, polycarbonate, polyamide, polyimide, polyamideimide, polyphenylene ether, polyphenylene sulfide, polyarylate, or polysulfone film is a carrier. It may be used as a film.

The thickness of the carrier film is not particularly limited, but is preferably 3 to 250 μm. When it is 3 μm or more, the film strength is sufficient, and when it is 250 μm or less, sufficient flexibility is obtained. From the above viewpoint, the thickness is more preferably 5 to 200 μm, and further preferably 7 to 150 μm. From the viewpoint of improving releasability from the stretchable resin layer, a film obtained by subjecting the base film to a release treatment with a silicone compound, a fluorine-containing compound, or the like may be used as necessary.

If necessary, a protective film may be attached on the stretchable resin layer to form a laminated film having a three-layer structure including a conductor foil or a carrier film, a stretchable resin layer, and a protective film.

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

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

Next, a method for manufacturing a wiring board according to an embodiment will be described. The wiring board according to one embodiment includes, for example, a step of preparing a laminate having a stretchable resin layer and a conductive foil laminated on the stretchable resin layer, a step of forming a via hole in the stretchable resin layer, A step of forming a plating layer such as a copper plating layer on the inner wall surface of the via hole; a step of forming an etching resist on the conductive foil; and exposing the etching resist; developing the etched resist after the exposure; It can be manufactured by a method including a step of forming a resist pattern covering a part, a step of removing a portion of the conductor film not covered with the resist pattern, and a step of removing the resist pattern.

As a method for obtaining a laminate having a stretchable resin layer and a conductor foil, any method may be used. For example, a varnish of a resin composition for forming a stretchable resin layer is applied to a conductor foil. And a method of laminating a conductive foil on a stretchable resin layer formed on a carrier film by a vacuum press or a laminator. When the resin composition for forming the stretchable resin layer contains a crosslinking component, the stretchable resin layer is formed by advancing a crosslinking reaction (curing reaction) of the crosslinking component by heating or light irradiation.

Any method may be used for laminating the stretchable resin layer on the carrier film on the conductor foil. For example, a roll laminator, a vacuum laminator, a vacuum press, or the like is used. From the viewpoint of production efficiency, it is preferable to laminate 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 μm. Within the above range, sufficient strength of the stretchable base material can be easily obtained, and since the drying can be sufficiently performed, the amount of residual solvent in the resin film can be reduced.

A laminate having conductor foils formed on both sides of the stretchable resin layer may be produced by further laminating a conductor foil on the surface of the stretchable resin layer opposite to the conductor foil. By providing the conductive foil on both surfaces of the stretchable resin layer, it is possible to suppress the warp of the laminated board during curing.

The via hole can be easily formed by drilling or laser processing. In drilling, a through-hole shape can be formed. On the other hand, in laser processing, a blind via shape can be formed in addition to a through-through hole shape, and the tolerance of wiring design can be further increased.

It is preferable to select drilling or laser processing depending on the shape and diameter of the via hole. It is preferable to use drilling when forming through vias and laser processing when forming non-penetrating blind via shapes.

A plating layer such as a copper plating layer can be formed by a known method. For example, after applying a plating catalyst for depositing palladium on the inner wall surface of a via hole, the electroless plating layer (conductor) having a thickness of 0.3 to 1.5 μm is immersed on the entire inner wall surface of the via hole by immersion in an electroless plating solution. Layer). If necessary, electrolytic plating (electroplating) can be further performed to adjust to a required thickness. As an electroless plating solution used for electroless plating, a known electroless plating solution can be used, and there is no particular limitation. Moreover, a well-known method can be used also about electrolytic plating, and there is no restriction | limiting in particular. As these plating (electroless plating, electrolytic plating), copper plating is preferable from the viewpoint of cost and resistance.

As a technique for forming a wiring pattern on a conductive foil of a laminated board (wiring board forming laminated board), a technique using etching or the like is generally used. For example, when copper foil is used as the conductor foil, a mixed solution of concentrated sulfuric acid and hydrogen peroxide, a ferric chloride solution, or the like can be used as the etching solution. A land portion around the via hole can be formed together with the wiring pattern.

Etching resists used for etching include, for example, Fotec H-7005 (trade name, manufactured by Hitachi Chemical Co., Ltd.), Fotech H-7030 (trade name, manufactured by Hitachi Chemical Co., Ltd.), and X-87 (Taiyo Holdings Co., Ltd.). ), Product name). The etching resist is usually removed after the wiring pattern is formed.

A stretchable device can be obtained by mounting various electronic elements on a wiring board.

This disclosure will be described more specifically with reference to the following reference example. However, the present disclosure is not limited to these reference examples.

Study 1
1-1. Preparation of varnish for forming elastic resin layer [Resin varnish A]
As component (A), 30 g of hydrogenated styrene butadiene rubber (Asahi Kasei Co., Ltd., Tuftec P1500, trade name) and 70 g of toluene were mixed with stirring to obtain resin varnish A.
[Resin varnish B]
As component (A), hydrogenated styrene-butadiene rubber (manufactured by JSR Corporation, Dynalon 2324P, trade name) 20 g, as component (B), butanediol acrylate (manufactured by Hitachi Chemical Co., Ltd., FANCL FA-124AS, trade name) ) 5 g, and 0.4 g of bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide (manufactured by BASF Corp., Irgacure 819, trade name) as component (C) and 15 g of toluene as a solvent while stirring. The resin varnish B was obtained by mixing.
[Resin varnish C]
(A) Acrylic polymer (manufactured by Kuraray Co., Ltd., Clarity LA2140, trade name) 20 g as component (A), aliphatic chain modified epoxy resin (DIC Corporation, EXA4816, trade name) 5 g as component (B), and (C) Resin varnish C was obtained by mixing 0.5 g of 2-phenylimidazole (manufactured by Shikoku Kasei Co., Ltd., 2PZ, trade name) as a component and 15 g of methyl ethyl ketone as a solvent while stirring.
[Resin varnish D]
25.0 g of methyl ethyl ketone was mixed with 50 g of a biphenyl aralkyl type epoxy resin (manufactured by Nippon Kayaku Co., Ltd., NC-3000H, trade name). Thereto was added 20 g of a phenol novolac-type phenolic resin (manufactured by DIC Corporation, TD2131, trade name), and 0.15 g of 2-phenylimidazole (manufactured by Shikoku Kasei Kogyo Co., Ltd., 2PZ, trade name) as a curing accelerator. Added. Then, the resin varnish D was obtained by diluting with methyl ethyl ketone.

1-2. Reference Example 1-1 for Producing Laminate with Conductive Layer 1-1
[Laminated film having stretchable resin layer]
A release-treated polyethylene terephthalate (PET) film (“Purex A31” manufactured by Teijin DuPont Films Ltd., thickness 25 μm) was prepared as a carrier film. Resin varnish A was applied onto the release-treated surface of this PET film using a knife coater ("SNC-350" manufactured by Yasui Seiki Co., Ltd.) The coating film was dried ("MSO-80TPS" manufactured by Futaba Kagaku Co., Ltd.). ]) Was dried at 100 ° C. for 20 minutes to form a stretchable resin layer having a thickness of 100 μm after coating. On the formed stretchable resin layer, the same release treatment PET film as the carrier film was formed. The laminated film A was obtained by pasting as a protective film in such a direction that the release treatment surface was on the stretchable resin layer side.
[Laminated board with conductor layer]
The protective film of the laminated film A was peeled off, and the stretchable resin layer of the laminated film A was laminated on the roughened surface side of a copper foil (manufactured by Nippon Electrolytic Co., Ltd., YGP-12, trade name). Using a vacuum pressure laminator (“V130” manufactured by Nichigo-Morton Co., Ltd.), pressure-bonding was performed under the conditions of a pressure of 0.5 MPa, a temperature of 90 ° C., and a pressurization time of 60 seconds to produce a laminate with a conductor layer.

Reference Example 1-2
Except for changing resin varnish A to resin varnish B and copper foil to another copper foil (BHY-82F-HA-V2-12 μm, trade name, manufactured by JX Metals Co., Ltd.), the same as Reference Example 1-1 Thus, a laminate having a copper foil and an uncured resin layer was obtained. Thereafter, the resin layer was cured by irradiating 2000 mJ / cm ^{2 of} ultraviolet rays (wavelength 365 nm) with an ultraviolet exposure machine (“ML-320FSAT” manufactured by Mikasa Co., Ltd.) to obtain a laminate with a conductor layer.

Reference Example 1-3
A laminate having a copper foil and an uncured resin layer was obtained in the same manner as in Reference Example 1-1 except that the resin varnish A was changed to the resin varnish C. Then, the resin layer was hardened on 180 degreeC 1 hour conditions using the dryer, and the laminated board with a conductor layer was obtained.

Comparative Reference Example 1-1
A laminate having a copper foil and an uncured resin layer was obtained in the same manner as in Reference Example 1-1 except that the resin varnish A was changed to the resin varnish D. Then, the resin layer was hardened on 180 degreeC 1 hour conditions using the dryer, and the laminated board with a conductor layer was obtained.

[Production and evaluation of wiring board]
As shown in FIG. 3, a test wiring board 1 having a stretchable resin layer 3 and a conductive foil 5 having a corrugated pattern formed on the stretchable resin layer 3 as a conductor layer was produced. First, an etching resist (manufactured by Hitachi Chemical Co., Ltd., Photoc RY-5325, product name) is attached to the conductor layer of each laminated board with a conductor layer with a roll laminator, and a photo tool having a corrugated pattern formed thereon is provided. Adhered. The etching resist was exposed with an energy amount of 50 mJ / cm ² using an EXM-1201 type exposure machine manufactured by Oak Manufacturing Co., Ltd. Next, spray development was performed for 240 seconds with a 1% by mass aqueous sodium carbonate solution at 30 ° C. to dissolve the unexposed portions of the etching resist, thereby forming a resist pattern having a wave shape. Subsequently, the copper foil of the part which is not covered with the resist pattern was removed with the etching liquid. Thereafter, the etching resist is removed by a peeling solution, and the wiring board 1 having the conductive foil 5 on the stretchable resin layer 3 having a wiring width of 50 μm and forming a wavy wiring pattern meandering along a predetermined direction X. Got.
When the obtained wiring board was pulled and deformed in the X direction to a strain of 10% and returned to its original state, the stretchable resin layer and the corrugated wiring pattern were observed. With respect to the stretchable resin layer and the wiring pattern, “A” indicates that no breakage occurred during extension, and “C” indicates that the breakage occurred.

Table 1 shows the evaluation results of Reference Examples 1-1 to 1-3 and Comparative Reference Example 1-1. In the wiring board having the corrugated wiring pattern formed by the laminated plates with the conductor layers of Reference Examples 1-1 to 1-3, the stretchable resin layer does not break even when stretched by 10%, and the corrugated wiring pattern It turned out that there was no problem with the appearance. On the other hand, in Comparative Reference Example 1-1, since the resin layer did not have elasticity, it was found that the resin layer was broken before stretching by 10%, and the wiring was also broken at the same time. By providing a via hole in the wiring board formed of the laminated board with the conductor layer of Reference Examples 1-1 to 1-3, it is possible to obtain a wiring board having high stretchability and capable of interlayer connection during lamination. .

Study 2
Reference Example 2-1
[Resin varnish]
(A) Maleic anhydride-modified styrene ethylene butadiene rubber (manufactured by KRATON Co., Ltd., FG1924GT, trade name) 10 g, (B) component as dicyclopentadiene type epoxy resin (DIC Corporation, EPICLON HP7200H, trade name) ) 2.5 g and 0.38 g of 1-benzyl-2-methylimidazole (manufactured by Shikoku Kasei Co., Ltd., 1B2MZ, trade name) as component (C) (curing accelerator) and 50 g of toluene are mixed with stirring. Thus, a resin varnish was obtained.

[Laminated film]
A release-treated polyethylene terephthalate (PET) film (“Purex A31” manufactured by Teijin DuPont Films Ltd., thickness 25 μm) was prepared as a carrier film. The resin varnish was applied onto the release-treated surface of this PET film using a knife coater ("SNC-350" manufactured by Yasui Seiki Co., Ltd.) The coating film was dried ("MSO-80TPS" manufactured by Futaba Kagaku Co., Ltd.). )) Was dried by heating at 100 ° C. for 20 minutes to form a resin layer having a thickness of 100 μm. On the formed resin layer, the same release treatment PET film as that of the carrier film was formed. A laminated film was obtained by pasting as a protective film in the direction toward the resin layer side.

[Preparation of conductor substrate]
An electrolytic copper foil having a roughened surface with a surface roughness Ra of 1.5 μm on the exposed resin layer after peeling off the protective film of the laminated film (F2-WS-12, trade name, manufactured by Furukawa Electric Co., Ltd.) Were stacked in such a direction that the roughened surface was on the resin layer side. In that state, an electrolytic copper foil is laminated to the resin layer under the conditions of a pressure of 0.5 MPa, a temperature of 90 ° C. and a pressurization time of 60 seconds using a vacuum pressure laminator (“V130” manufactured by Nikko Materials Co., Ltd.). did. Thereafter, a conductive substrate having a stretchable resin layer, which is a cured product of the resin layer, and an electrolytic copper foil is heated by heating at 180 ° C. for 60 minutes in a dryer (“MSO-80TPS” manufactured by Futaba Kagaku Co., Ltd.). Obtained.

Reference Example 2-2
(A) Maleic anhydride-modified styrene ethylene butadiene rubber (manufactured by KRATON Co., Ltd., FG1924GT, trade name) 10 g, (B) component as dicyclopentadiene type epoxy resin (DIC Corporation, EPICLON HP7200H, trade name) 2.5 g, 1-benzyl-2-methylimidazole (manufactured by Shikoku Kasei Co., Ltd., 1B2MZ, trade name) 0.38 g as component (C) (curing accelerator), phenolic antioxidant (ADEKA Corporation) Made of AO-60, trade name) 0.1 g, and phosphite antioxidant (produced by ADEKA, 2112, trade name) 0.1 g and toluene 50 g were mixed with stirring to obtain a resin varnish. Obtained. Using the obtained resin varnish, a laminated film having a resin layer and a conductor substrate were produced in the same manner as in Reference Example 2-1.

Evaluation [heat resistance test]
The laminated film was heated at 180 ° C. for 60 minutes to cure the resin layer, thereby forming a stretchable resin layer. After removing the carrier film and the protective film, the temperature of FIG. 4 conforming to IPC / JEDEC J-STD-020 is applied to the stretchable resin layer using a nitrogen reflow system (Tamura Seisakusho Co., Ltd., TNV-EN). A heat resistance test in which heat treatment was performed with a profile was performed. The elongation and tensile modulus of the stretchable resin layer before and after the heat resistance test were measured. The conductor substrate was also subjected to the same heat resistance test, and the 90 degree peel strength before and after the heat resistance test was measured.

[Tensile modulus and elongation at break]
A test piece of a strip-shaped stretchable resin layer having a length of 40 mm and a width of 10 mm was prepared. A tensile test of this test piece was performed using an autograph (“EZ-S” manufactured by Shimadzu Corporation) to obtain a stress-strain curve. From the obtained stress-strain curve, the tensile modulus and elongation at break were determined. The tensile test was performed under the conditions of a distance between chucks of 20 mm and a tensile speed of 50 mm / min. The tensile elastic modulus was obtained from the slope of the stress-strain curve in the range of 0.5 to 1.0 N stress. The strain at the time when the test piece broke was recorded as the elongation at break.

[Adhesion (90 degree peel strength)]
The 90 degree peel strength between the copper foil and the stretchable resin layer was measured by a peel test in which the copper foil was peeled from the conductor substrate at a peel angle of 90 degrees.

[tack]
The laminated film was heated at 180 ° C. for 60 minutes to cure the resin layer and form a stretchable resin layer. The carrier film and the protective film were removed from the laminated film after curing, and a test piece of a laminated film having a length of 70 mm and a width of 20 mm was prepared. The tack of the surface of the exposed resin layer was measured using a tacking tester (“TACII” manufactured by Resuka Co., Ltd.). The measurement conditions were set to a constant load mode, an immersion speed of 120 mm / min, a test speed of 600 mm / min, a load of 100 gf, a load holding time of 1 s, and a temperature of 30 ° C.

As shown in Table 2, the stretchable resin layers of Reference Example 2-1 and Reference Example 2-2 maintained excellent stretchability and high adhesion to the copper foil even after the heat resistance test. Further, the tackiness of the resin layer was moderately low, and the handleability of the resin layer was excellent. By forming wiring patterns and via holes in the conductor substrates of Reference Examples 2-1 and 2-2 above, it has high stretchability and can be connected between layers at the time of lamination, and excellent stretchability even after a heat resistance test. And excellent adhesion between the copper foil and the stretchable resin layer can be maintained, and a wiring board having a reasonably low tack of the stretchable resin layer can be obtained.

DESCRIPTION OF SYMBOLS 10 ... Stretchable resin layer, 20 ... Conductive foil, 30 ... Via hole, 40 ... Electroless copper plating layer, 50 ... Land part, 100 ... Wiring board.

Claims

An elastic resin layer;
Conductor foil provided on the stretchable resin layer and forming a wiring pattern;
Via holes provided in the stretchable resin layer;
Having a wiring board.
The wiring board according to claim 1, wherein the conductive foil is a copper foil.
The wiring board according to claim 1 or 2, wherein the via hole is formed by a laser or a drill.
4. The wiring board according to claim 1, wherein the via hole has a diameter of 10 to 500 μm.
The wiring board according to any one of claims 1 to 4, further comprising a copper plating layer provided on an inner wall surface of the via hole.
Provided around the via hole on the stretchable resin layer, and has a land portion connected to the copper plating layer,
The wiring board according to claim 5, wherein a width of the land portion from an end face of the via hole is 10 μm or more.
The stretchable resin layer contains (A) a rubber component,
The rubber component is acrylic rubber, isoprene rubber, butyl rubber, styrene butadiene rubber, butadiene rubber, acrylonitrile butadiene rubber, silicone rubber, urethane rubber, chloroprene rubber, ethylene propylene rubber, fluorine rubber, sulfurized rubber, epichlorohydrin rubber, and chlorinated butyl rubber. The wiring board according to any one of claims 1 to 6, comprising at least one selected from the group consisting of:
The wiring board according to any one of claims 1 to 7, wherein the stretchable resin layer comprises (A) a cured product of a resin composition containing a rubber component.
The wiring board according to claim 8, wherein the rubber component (A) includes a rubber having a crosslinking group.
The wiring board according to claim 9, wherein the cross-linking group is at least one of an acid anhydride group or a carboxyl group.
The resin composition further contains (B) a crosslinking component,
The crosslinking component is at least one reaction selected from the group consisting of (meth) acrylic groups, vinyl groups, epoxy groups, styryl groups, amino groups, isocyanurate groups, ureido groups, cyanate groups, isocyanate groups, and mercapto groups. The wiring board according to any one of claims 8 to 10, which is a compound having a functional group.
The wiring board according to any one of claims 8 to 11, wherein the resin composition further contains at least one of (C) a curing agent or a curing accelerator.
The wiring board according to any one of claims 7 to 12, wherein a content of the rubber component is 30 to 100% by mass with respect to 100% by mass of the stretchable resin layer.
Preparing a laminate having a stretchable resin layer and a conductive foil laminated on the stretchable resin layer;
Forming via holes in the stretchable resin layer;
Forming an etching resist on the conductor foil;
Exposing the etching resist, developing the exposed etching resist to form a resist pattern covering a part of the conductor foil;
Removing the portion of the conductor foil not covered by the resist pattern;
Removing the resist pattern;
The method for manufacturing a wiring board according to any one of claims 1 to 13, comprising:
The method according to claim 14, further comprising a step of forming a copper plating layer on an inner wall surface of the via hole after the step of forming a via hole in the stretchable resin layer.
A stretchable device comprising the wiring board according to any one of claims 1 to 13 and an electronic element mounted on the wiring board.