TWI753071B - Wiring board, method for manufacturing the same, and stretchable element - Google Patents

Abstract

The present invention discloses a wiring substrate 100 including: a stretchable resin layer 10 ; a conductor foil 20 disposed on the stretchable resin layer 10 and forming a wiring pattern;

Description

Wiring board, method for manufacturing the same, and stretchable element

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

In recent years, in the fields of wearable devices and health care-related devices, for example, flexibility and elasticity are required that can be used along curved surfaces or joints of the body, and that it is difficult to cause poor connection even when wearing and taking off. . In order to constitute such a device, a member having high elasticity is required.

As a method of realizing a member having high stretchability, there has been reported a method of mounting a wafer, a semiconductor device, etc. on a flexible substrate having a polyimide resin having high folding endurance as a base, and using a stretchable resin The composition is sealed (refer to Patent Document 1). [Prior Art Document] [Patent Document]

[Patent Document 1] International Publication No. 2016/080346

THE PROBLEM TO BE SOLVED BY THE INVENTION As described in Patent Document 1, by making the sealing material stretchable, it is possible to realize a stretchable member which is difficult to realize in the conventional sealing material. On the other hand, since the base material does not have stretchability, it is difficult to have higher stretchability. Therefore, a wiring board having higher stretchability is required. In addition, there is a demand for a wiring board that has higher stretchability and enables interlayer connection during lamination.

Under such circumstances, an object of the present disclosure is to provide a wiring board having high stretchability and enabling interlayer connection during lamination, a manufacturing method thereof, and a stretchable element. [Means of Solving Problems]

The inventors of the present invention have made intensive studies in order to solve the above-mentioned problems, and as a result, they have found that high stretchability is imparted by using a stretchable resin layer in the base substrate, and the stretchable resin layer and the conductor foil are combined and incorporated into the base material. The above-mentioned problems can be solved by providing a via hole in the stretchable resin layer.

That is, an aspect of the present disclosure is to provide the following inventions. [1] A wiring board comprising: a stretchable resin layer, a conductor foil provided on the stretchable resin layer and forming a wiring pattern, and a through hole provided in the stretchable resin layer. [2] The wiring board according to the above [1], wherein the conductor foil is a copper foil. [3] The wiring board according to the above [1] or [2], wherein the through hole is formed by laser or drilling. [4] The wiring board according to any one of the above [1] to [3], wherein the diameter of the through hole is 10 μm to 500 μm. [5] The wiring board according to any one of the above [1] to [4], further comprising a copper plating layer provided on the inner wall surface of the through hole. [6] The wiring board according to the above [5], further comprising a land portion provided around the through hole on the stretchable resin layer and connected to the copper plating layer, the land portion The width of the portion from the end face of the through hole is 10 μm or more. [7] The wiring board according to any one of the above [1] to [6], wherein the stretchable resin layer contains (A) a rubber component containing a rubber component selected from the group consisting of acrylic rubber, isoprene ethylene rubber, butyl rubber, styrene butadiene rubber, butadiene rubber, acrylonitrile butadiene rubber, silicone rubber, urethane rubber, chloroprene rubber, ethylene propylene rubber, fluorine rubber, At least one of the group consisting of vulcanized rubber, epichlorohydrin rubber, and chlorobutyl rubber. [8] The wiring board according to any one of the above [1] to [7], wherein the stretchable resin layer contains a cured product of a resin composition containing the (A) rubber component. [9] The wiring board according to the above [8], wherein the (A) rubber component contains a rubber having a crosslinking group. [10] The wiring board according to the above [9], wherein the crosslinking group is at least one of an acid anhydride group and a carboxyl group. [11] The wiring board according to any one of the above-mentioned [8] to [10], wherein the resin composition further contains (B) a cross-linking component having a component selected from the group consisting of (methyl) ) At least one reactive group in the group consisting of acrylic group, vinyl group, epoxy group, styryl group, amine group, isocyanurate group, urea group, cyanate group, isocyanate group, and mercapto group compound of. [12] The wiring board according to any one of the above [8] to [11], wherein the resin composition further contains (C) at least one of a curing agent and a curing accelerator. [13] The wiring board according to any one of the above [7] to [12], wherein the content of the rubber component is 30% by mass to 100% by mass relative to 100% by mass of the stretchable resin layer . [14] A method for producing the wiring board according to any one of the above [1] to [13], comprising: preparing a resin layer having a stretchable resin layer and being laminated on the stretchable resin layer A step of forming a laminate of conductor foils, a step of forming a via hole in the stretchable resin layer, a step of forming an etching resist on the conductor foil, exposing the etching resist, and exposing the exposed A step of developing the etching resist to form a resist pattern covering a part of the conductor foil, a step of removing the conductor foil of a part not covered by the resist pattern, and the The step of resist pattern removal. [15] The method according to the above [14], which further includes the step of forming a copper plating layer on the inner wall surface of the through hole after the step of forming the through hole in the stretchable resin layer. [16] A stretchable element comprising: the wiring board according to any one of the above [1] to [13], and an electronic device mounted on the wiring board. [Effect of invention]

According to the present disclosure, it is possible to provide a wiring board having high stretchability and enabling interlayer connection during lamination, a manufacturing method thereof, and a stretchable element. In addition, by using the wiring board provided by the present disclosure, a multi-layer wiring board having elasticity and high density can be formed.

Hereinafter, preferred embodiments of the present disclosure will be described in detail with reference to the drawings. In addition, in the following description, the same code|symbol is attached|subjected to the same or equivalent part, and the repeated description is abbreviate|omitted.

In this specification, "(meth)acrylate" means at least one of acrylate and its corresponding methacrylate. The same applies to other similar expressions such as "(meth)acrylic acid". Unless otherwise specified, the materials exemplified below may be used alone or in combination of two or more. The numerical range represented using "-" represents the range including the numerical values described before and after the "-" as the minimum value and the maximum value, respectively. The term "A or B" may include either of A and B, and may include both.

In the numerical ranges described stepwise in this specification, the upper limit or the lower limit of the numerical range in one stage may be replaced with the upper limit or the lower limit of the numerical range in another stage. In addition, in the numerical range described in this specification, the upper limit value or the lower limit value of this numerical range can be replaced with the value shown in an Example (reference example).

A wiring board according to one embodiment includes a stretchable resin layer; a conductor foil provided on the stretchable resin layer and forming a wiring pattern; and a through hole provided in the stretchable resin layer.

FIG. 1 is a cross-sectional view showing an embodiment of a wiring board. The wiring board 100 shown in FIG. 1 includes: a stretchable resin layer 10 as a base material; a conductor foil 20 provided on the stretchable resin layer 10 and forming a wiring pattern; through holes 30 formed in the stretchable resin layer 10; The electroless copper plating layer 40 provided on the inner wall surface of the through hole 30 ;

The wiring board of the present embodiment has superior stretchability compared with the case of using a conventional board by using the base material formed of the stretchable resin layer 10 , and by forming the through holes 30 and performing electroless copper plating, By forming the electroless copper plating layer 40, interlayer connection can be realized, and a wiring design equivalent to that of a conventional wiring board can be realized. Thereby, it is possible to manufacture a multilayer wiring board which has excellent stretchability and can realize high-density wiring.

From the viewpoint of the precipitation of electroless copper plating, the diameter (diameter) D of the opening of the through hole 30 before the electroless copper plating layer 40 is formed is preferably 10 μm or more, more preferably 40 μm or more, The relationship between the through-hole workability and the wiring density 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 μm to 1.5 μm, more preferably 0.3 μm to 1.0 μm, from the viewpoint of the adhesiveness with the stretchable resin layer 10 .

In addition, for the purpose of increasing the thickness of the conductor, 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 from the viewpoint of through-hole connection reliability, it is preferably 1 μm to 100 μm, and more preferably 10 μm to 50 μm.

The width W of the land portion 50 from the end face of the through hole 30 is preferably 10 μm or more, more preferably 100 μm or more, in order to maintain the interlayer connection by the electroless copper plating layer 40 during expansion and contraction of the substrate.

The land portion 50 is a conductor layer provided around the through hole 30 , and is preferably formed on the surface of the stretchable resin layer 10 so as to be concentric with the through hole 30 . The land portion 50 may be formed of the same material as the conductor foil 20 to be 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 is within the aforementioned range.

The conductor foil 20 may form a corrugated wiring pattern meandering in the direction from the front side toward the back side in FIG. 1 . In addition, the shape of the wiring pattern of the conductor foil 20 is not specifically limited, It can determine suitably.

The elastic modulus of the conductor foil 20 may be 40 GPa to 300 GPa. Since the elastic modulus of the conductor foil is 40 GPa to 300 GPa, there is a tendency that breakage of the conductor foil due to elongation of the wiring board is difficult to occur. From the same viewpoint, the elastic modulus of the conductor foil may be 50 GPa or more, or 280 GPa or more, and may be 60 GPa or less, or 250 GPa or less. The elastic modulus of the conductor foil here may be a value measured by a resonance method.

The conductor foil may be a metal foil. Examples of metal foils include: copper foil, titanium foil, stainless steel foil, nickel foil, permalloy foil, 42 alloy (42 alloy) foil, Kovar foil, and Nichrome foil , beryllium copper foil, phosphor bronze foil, brass foil, zinc cupronickel 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, etc. The conductor foil is preferably 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, copper foil is preferably used.

The copper foil is not particularly limited, and for example, electrolytic copper foil and rolled copper foil that are generally used in copper-clad laminates, flexible wiring boards, and the like can be used. As commercially available electrolytic copper foils, for example, F0-WS-18 (manufactured by Furukawa Electric Co., Ltd., trade name), NC-WS-20 (manufactured by Furukawa Electric Co., Ltd., trade name), YGP-12 ( Nippon Electrolyte Co., Ltd., trade name), GTS-18 (Furukawa Electric Co., Ltd., trade name), and F2-WS-12 (Furukawa Electric Co., Ltd. manufacture, trade name). As rolled copper foil, for example, TPC foil (manufactured by JX metal (stock), trade name), HA foil (manufactured by JX metal (stock), trade name), HA-V2 foil (manufactured by JX metal (stock), trade name) name), and C1100R (manufactured by Mitsui Sumitomo Metal Mining Shinco (stock), trade name). From a viewpoint of further improving the adhesiveness with a stretchable resin layer, it is preferable to use the copper foil which performed the roughening process. In addition, from the viewpoint of folding endurance and stretchability, it is preferable to use a rolled copper foil.

The stretchable resin layer 10 may have, for example, stretchability such that the recovery rate after tensile deformation to a strain of 20% is 80% or more. This recovery rate is calculated|required by the tensile test of the measurement sample using a stretchable resin layer. Let the strain (displacement amount) applied in the first tensile test be X, and the difference between the position when the load is started and X when the tensile test is repeated after returning to the initial position is Y, and the formula : R(%)=Y/X×100% The calculated R is defined as the recovery rate. The recovery rate can be determined by setting X to 20%. FIG. 2 is a stress-strain curve showing a measurement example of the recovery rate. If the recovery rate is 80% or more, repeated use can be tolerated, so the recovery rate is more preferably 85% or more, and more preferably 90% or more.

The elastic modulus of the stretchable resin layer is preferably 0.1 MPa or more and 1000 MPa or less. When the elastic modulus is 0.1 MPa or more and 1000 MPa or less, there is a tendency that the handleability and flexibility as a base material are particularly excellent. From this viewpoint, 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 easily obtained. From this viewpoint, the elongation at break is more preferably 150% or more, more preferably 200% or more, particularly preferably 300% or more, and most 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 may contain (A) a rubber component. The stretchability is easily imparted to the stretchable resin layer mainly by the rubber component. The content of the rubber component may be 30% by mass to 100% by mass relative to 100% by mass of the stretchable resin layer.

The rubber component may contain, for example, acrylic rubber, isoprene rubber, butyl rubber, styrene butadiene rubber, butadiene rubber, acrylonitrile butadiene rubber, silicone rubber, urethane rubber, neoprene At least one of diene rubber, ethylene propylene rubber, fluororubber, vulcanized rubber, epichlorohydrin rubber, and chlorobutyl rubber. From the viewpoint of avoiding damage to wiring 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 the group consisting of styrene butadiene rubber, butadiene rubber, and butyl rubber.

Examples of commercially available acrylic rubbers include "Nipol AR series" manufactured by ZEON Co., Ltd., "Kuraray Co., Ltd." manufactured by Kuraray Co., Ltd. series".

As a commercial item of isoprene rubber, "Nipol IR series" by ZEON Co., Ltd. is mentioned, for example.

As a commercial item of butyl rubber, "BUTYL series" by JSR Corporation is mentioned, for example.

Examples of commercial products of styrene butadiene rubber include "Dynaron SEBS series" and "Dynaron HSBR series" manufactured by JSR Corporation, Japan Kraton Polymers ( "Kraton D polymer series" manufactured by Kraton polymers Japan (stock), and "AR series" manufactured by Aronkasei (stock).

As a commercial item of a butadiene rubber, "Nipol BR series" by Japan Zeon Co., Ltd. is mentioned, for example.

As a commercial item of acrylonitrile butadiene rubber, "JSR NBR series" by JSR Corporation is mentioned, for example.

As a commercial item of silicone rubber, "KMP series" by Shin-Etsu Silicone Co., Ltd. is mentioned, for example.

As a commercial item of ethylene propylene rubber, "JSR EP series" by JSR Corporation is mentioned, for example.

As a commercial item of fluororubber, "DAIEL series" by Daikin Co., Ltd. is mentioned, for example.

As a commercial item of epichlorohydrin rubber, "Hydrin series" by Japan Zeon Co., Ltd. is mentioned, for example.

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

The rubber component may also contain a rubber having a crosslinking group. By using the rubber which has a crosslinking group, there exists a tendency for the heat resistance of a stretchable resin layer to be easily improved. The crosslinking group should just be a reactive group which can advance the reaction of crosslinking the molecular chain of the rubber component. Examples thereof include reactive groups, acid anhydride groups, amino groups, hydroxyl groups, epoxy groups, and carboxyl groups which the crosslinking component (B) described later has.

The rubber component may also contain rubber having at least one crosslinking group among acid anhydride groups or carboxyl groups. As an example of the rubber which has an acid anhydride group, the rubber partially modified with maleic anhydride is mentioned. The rubber partially modified with maleic anhydride is a polymer including a structural unit derived from maleic anhydride. As a commercial item of rubber partially modified with maleic anhydride, there is, for example, a styrene-based elastomer "tufprene 912" manufactured by Asahi Kasei Co., Ltd.

The rubber partially modified with maleic anhydride may also be a hydrogenated styrene-based elastomer partially modified with maleic anhydride. Effects such as improvement in weather resistance can also be expected from the hydrogenated styrene-based elastomer. The hydrogenated styrene-based elastomer is an elastomer obtained by adding hydrogen to the unsaturated double bond of the styrene-based elastomer having a soft segment including an unsaturated double bond. Examples of commercially available hydrogenated styrene-based elastomers partially modified with maleic anhydride include "FG1901" and "FG1924" manufactured by Kraton Polymers Japan Co., Ltd., and Asahi Kasei ( "Tuftec M1911", "tuftec M1913", "tuftec M1943" manufactured by the company.

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 coatability. The weight average molecular weight (Mw) here is a standard polystyrene conversion value obtained by gel permeation chromatography (Gel Permeation Chromatography, GPC).

The stretchable resin layer may be a cured product of a resin composition containing the (A) rubber component. In this case, a curable resin composition is used as the resin composition for forming the stretchable resin layer. The curable resin composition may further contain (B) a crosslinking component, for example. That is, the stretchable resin layer may further contain the cross-linked polymer of the (B) cross-linked component. For example, the cross-linking component may be selected from (meth)acrylic group, vinyl group, epoxy group, styryl group, amine group, isocyanurate group, urea group, cyanate group, isocyanate group, mercapto group, A compound of at least one reactive group in the group consisting of a hydroxyl group and a carboxyl group can form a cured product including a cross-linked polymer 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 may be used alone or in combination of two or more.

As a compound which has a (meth)acrylic group, a (meth)acrylate compound is mentioned. The (meth)acrylate compound may be any one of monofunctional, difunctional or polyfunctional, and is not particularly limited, but in order to obtain sufficient curability, difunctional or polyfunctional (meth)acrylic acid is preferred ester.

Examples of monofunctional (meth)acrylates include methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, isobutyl (meth)acrylate, and (meth)acrylate. ) tert-butyl acrylate, butoxyethyl (meth)acrylate, isoamyl (meth)acrylate, hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, (meth)acrylate (meth)heptyl 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, cetyl (meth)acrylate, stearyl (meth)acrylate (meth)acrylic acid behenyl ester, (meth)acrylic acid-2-hydroxyethyl ester, (meth)acrylic acid-2-hydroxypropyl ester, (meth)acrylic acid-3-chloro-2-hydroxyl Propyl ester, 2-hydroxybutyl (meth)acrylate, methoxypolyethylene glycol (meth)acrylate, ethoxypolyethylene glycol (meth)acrylate, methoxypolypropylene glycol (methyl) (methyl) acrylate, ethoxylated polypropylene glycol (meth)acrylate, aliphatic (meth)acrylate such as mono(2-(meth)acrylooxyethyl) succinate; (methyl) Cyclopentyl acrylate, cyclohexyl (meth)acrylate, dicyclopentyl (meth)acrylate, dicyclopentenyl (meth)acrylate, isobornyl (meth)acrylate, tetrahydrophthalic acid Alicyclic (meth)acrylates such as mono(2-(meth)acryloyloxyethyl) ester and mono(2-(meth)acryloyloxyethyl) hexahydrophthalate; Benzyl (meth)acrylate, phenyl (meth)acrylate, o-biphenyl (meth)acrylate, 1-naphthyl (meth)acrylate, 2-naphthalene (meth)acrylate base ester, phenoxyethyl (meth)acrylate, p-cumylphenoxyethyl (meth)acrylate, o-phenylphenoxyethyl (meth)acrylate, (meth)acrylic acid-1- Naphthoxyethyl, (meth)acrylate-2-naphthoxyethyl, phenoxypolyethylene glycol (meth)acrylate, nonylphenoxypolyethylene glycol (meth)acrylate, Phenoxy polypropylene glycol (meth)acrylate, (meth)acrylate-2-hydroxy-3-phenoxypropyl, (meth)acrylate-2-hydroxy-3-(o-phenylphenoxy) Aromatic ( Meth)acrylate; 2-tetrahydrofurfuryl (meth)acrylate, N-(meth)acrylooxyethylhexahydrophthalimide, 2-(meth)acryloyloxy Heterocyclic (meth)acrylates such as ethyl-N-carbazole, and caprolactone modifications of these compounds. Among these, the aliphatic (meth)acrylate and the aromatic (meth)acrylic acid are preferred from the viewpoints of compatibility with styrene-based elastomers, transparency, and heat resistance ester.

As difunctional (meth)acrylate, for example, ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, Ethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylic acid Esters, 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, neopentyl 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, glycerol di(meth)acrylate, tricyclodecane dimethanol (meth)acrylate, ethoxylated-2-methyl-1, Aliphatic (meth)acrylates such as 3-propylene glycol di(meth)acrylate; cyclohexanedimethanol (meth)acrylate, ethoxylated cyclohexanedimethanol (meth)acrylate, propoxy Cyclohexanedimethanol (meth)acrylate, ethoxylated propoxylated cyclohexanedimethanol (meth)acrylate, tricyclodecanedimethanol (meth)acrylate, ethoxy Tricyclodecane dimethanol (meth)acrylate, propoxylated tricyclodecane dimethanol (meth)acrylate, ethoxylated propoxylated tricyclodecane dimethanol (meth)acrylic acid Esters, ethoxylated hydrogenated bisphenol A di(meth)acrylate, propoxylated hydrogenated bisphenol A di(meth)acrylate, ethoxylated propoxylated hydrogenated bisphenol A di(meth)acrylate ) acrylate, ethoxylated hydrogenated bisphenol F di(meth)acrylate, propoxylated hydrogenated bisphenol F di(meth)acrylate, ethoxylated propoxylated hydrogenated bisphenol F di(meth)acrylate Alicyclic (meth)acrylates such as meth)acrylates; 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 Propylene Oxylated bisphenol F di(meth)acrylate, ethoxylated bisphenol AF di(meth)acrylate, propoxylated bisphenol AF di(meth)acrylate, ethoxylated propoxy Alkylated bisphenol AF di(meth)acrylate, ethoxylated pyrene di(meth)acrylate, propoxylated pyrene di(meth)acrylate, ethoxylated propoxylated pyrene Aromatic (meth)acrylates such as type di(meth)acrylate; ethoxylated isocyanurate di(meth)acrylate, propoxylated isocyanurate di(meth)acrylate, Heterocyclic (meth)acrylates such as ethoxylated propoxylated isocyanurate di(meth)acrylate; caprolactone modified forms of these compounds; neopentyl Aliphatic epoxy (meth)acrylates such as alcohol-type epoxy (meth)acrylates; cyclohexanedimethanol-type epoxy (meth)acrylates, hydrogenated bisphenol A-type epoxy (methyl) Alicyclic epoxy (meth)acrylates such as epoxy (meth)acrylates and hydrogenated bisphenol F-type epoxy (meth)acrylates; and resorcinol-type epoxy (meth)acrylates, bis Phenol A-type epoxy (meth)acrylate, Bisphenol F-epoxy (meth)acrylate, Bisphenol AF-type epoxy (meth)acrylate, Phenyl epoxy (meth) Aromatic epoxy (meth)acrylates such as acrylates and the like. Among these, the aliphatic (meth)acrylate and the aromatic (meth)acrylic acid are preferred from the viewpoints of compatibility with styrene-based elastomers, transparency, and heat resistance ester.

As trifunctional or higher polyfunctional (meth)acrylates, for example, trimethylolpropane tri(meth)acrylate, ethoxylated trimethylolpropane tri(meth)acrylate, propoxy Trimethylolpropane tri(meth)acrylate, ethoxylated propoxylated trimethylolpropane 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, ethoxy Pentaerythritol tetra(meth)acrylate, propoxylated pentaerythritol tetra(meth)acrylate, ethoxylated propoxylated pentaerythritol tetra(meth)acrylate, di-trimethylolpropane tetraacrylate , Dipentaerythritol hexa(meth)acrylate and other aliphatic (meth)acrylates; ethoxylated isocyanurate tri(meth)acrylate, propoxylated isocyanurate tri(meth)acrylic acid Heterocyclic (meth)acrylates such as esters, ethoxylated propoxylated isocyanurate tri(meth)acrylate, etc.; caprolactone modified forms of these compounds; and phenol novolac epoxy resins Aromatic epoxy (meth)acrylate such as epoxy (meth)acrylate and cresol novolac epoxy (meth)acrylate. Among these, the aliphatic (meth)acrylate and the aromatic (meth)acrylic acid are preferred from the viewpoints of compatibility with styrene-based elastomers, transparency, and heat resistance ester.

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

The epoxy group-containing compound is not particularly limited as long as it has an epoxy group in the molecule, and may be, for example, a normal epoxy resin. The epoxy resin may be any one of monofunctional, difunctional, or polyfunctional, and is not particularly limited, but in order to obtain sufficient curability, a difunctional or polyfunctional epoxy resin is preferred.

As an epoxy resin, a bisphenol A type, a bisphenol F type, a phenol novolak type, a naphthalene type, a dicyclopentadiene type, a cresol novolak type, etc. are mentioned. An epoxy resin modified in an aliphatic chain is preferable because flexibility can be imparted. Examples of commercially available aliphatic chain-modified epoxy resins include EXA-4816 manufactured by DIC Corporation. From the viewpoint of curability, low viscosity, and heat resistance, a phenol novolak type, a cresol novolak type, a naphthalene type, and a dicyclopentadiene type can be selected. These epoxy resins may be used alone or in combination of two or more.

The content of the cross-linked polymer formed from the cross-linking component is preferably 10% by mass to 50% by mass based on the mass of the stretchable resin layer. When content of the crosslinked polymer which consists of a crosslinked component is the said range, there exists a tendency for the adhesive force with a conductor foil to improve in the state which maintains the characteristic of a stretchable resin layer. From the above viewpoints, the content of the cross-linked polymer formed from the cross-linking component is more preferably 15% by mass 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 for forming the same may further contain an additive as the component (C). (C) The additive may be at least one of a hardener and a hardening accelerator. The hardening agent is a compound that itself participates in the hardening reaction, and the hardening accelerator is a compound that functions as a catalyst for the hardening reaction. Compounds that function as both hardeners and hardening accelerators can also be used. The hardener can also 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 etc., you may add a polymerization initiator. The polymerization initiator is not particularly limited as long as it is a compound that initiates polymerization by heating or irradiation with ultraviolet rays, and for example, a thermal radical polymerization initiator or a photoradical polymerization initiator can be used. A thermal radical initiator is preferable in that the reaction of the resin composition proceeds uniformly. Since it is a photoradical initiator, since it can harden|cure at room temperature, it is preferable in the point which can prevent the deterioration by heat of an element, and the point which can suppress the curvature of a stretchable resin layer.

Examples of thermal radical polymerization initiators include ketone peroxides such as methyl ethyl ketone peroxide, cyclohexanone peroxide, and methyl cyclohexanone peroxide; tributylperoxy)cyclohexane, 1,1-bis(tert-butylperoxy)-2-methylcyclohexane, 1,1-bis(tert-butylperoxy)-3 ,3,5-trimethylcyclohexane, 1,1-bis(third hexylperoxy)cyclohexane, 1,1-bis(third hexylperoxy)-3,3,5-tri Peroxy ketals such as methylcyclohexane; hydroperoxides such as p-menthane hydroperoxide; α,α'-bis(tert-butylperoxy)diisopropylbenzene, dicumyl peroxide Dialkyl peroxides such as tert-butyl cumyl peroxide and di-tert-butyl peroxide; octyl peroxide, lauryl peroxide, stearyl peroxide, benzyl Diacyl peroxides such as acyl peroxide; bis(4-tert-butylcyclohexyl) peroxydicarbonate, di-2-ethoxyethyl peroxydicarbonate, di- peroxydicarbonate Peroxycarbonates such as 2-ethylhexyl, di-3-methoxybutyl peroxycarbonate; tert-butyl peroxytrimethyl acetate, tert-hexyl peroxytrimethyl acetate, peroxy- 2-Ethylhexanoic acid-1,1,3,3-tetramethylbutyl ester, 2,5-dimethyl-2,5-bis(2-ethylhexanoylperoxy)hexane, peroxy Oxy-2-ethylhexanoic acid tertiary hexyl ester, peroxy-2-ethylhexanoic acid tertiary butyl ester, peroxyisobutyric acid tertiary butyl ester, peroxyisopropyl monocarbonate tertiary hexyl ester, peroxyisopropyl monocarbonate Oxy-3,5,5-trimethylhexanoic acid 3-butyl ester, peroxylaurate 3-butyl ester, peroxyisopropyl monocarbonate 3-butyl peroxy-2-ethylhexyl monocarbonate Tributyl, 3-butyl peroxybenzoate, 3-hexyl peroxybenzoate, 2,5-dimethyl-2,5-bis(benzylperoxy)hexane, peroxyacetic acid Peroxyesters such as tert-butyl ester; and 2,2'-azobisisobutyronitrile, 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis (4-methoxy-2'-dimethylvaleronitrile) and other azo compounds. Among these, from the viewpoints of curability, transparency, and heat resistance, the diacyl peroxide, the peroxyester, and the azo compound are preferred.

Examples of photo-radical polymerization initiators include benzoin ketals such as 2,2-dimethoxy-1,2-diphenylethane-1-one; 1-hydroxycyclohexyl phenyl ketone, 2 -Hydroxy-2-methyl-1-phenylpropan-1-one, 1-[4-(2-hydroxyethoxy)phenyl]-2-hydroxy-2-methyl-1-propane-1- Alpha-hydroxy ketones such as ketones; 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butan-1-one, 1,2-methyl-1-[4 -(Methylthio)phenyl]-2-morpholinopropan-1-one and other α-amino ketones; 1-[4-(phenylthio)phenyl]-1,2-octanedione-2 -(benzyl) oxime iso-oxime ester; bis(2,4,6-trimethylbenzyl) phenylphosphine oxide, bis(2,6-dimethoxybenzyl)-2 ,4,4-trimethylpentylphosphine oxide, 2,4,6-trimethylbenzyldiphenylphosphine oxide and other phosphine oxides; 2-(o-chlorophenyl)-4,5-diphenyl Imidazole dimer, 2-(o-chlorophenyl)-4,5-bis(methoxyphenyl)imidazole dimer, 2-(o-fluorophenyl)-4,5-diphenylimidazole Polymer, 2-(o-methoxyphenyl)-4,5-diphenylimidazole dimer, 2-(p-methoxyphenyl)-4,5-diphenylimidazole dimer, etc. 2 ,4,5-Triarylimidazole dimer; Benzophenone, N,N,N',N'-tetramethyl-4,4'-diaminobenzophenone, N,N,N' ,N'-tetraethyl-4,4'-diaminobenzophenone, 4-methoxy-4'-dimethylaminobenzophenone and other benzophenone compounds; 2-ethyl Anthraquinone, phenanthraquinone, 2-tert-butylanthraquinone, octamethylanthraquinone, 1,2-benzoanthraquinone, 2,3-benzoanthraquinone, 2-phenylanthraquinone, 2,3- Diphenylanthraquinone, 1-chloroanthraquinone, 2-methylanthraquinone, 1,4-naphthoquinone, 9,10-phenanthraquinone, 2-methyl-1,4-naphthoquinone, 2,3-diquinone Quinone compounds such as methyl anthraquinone; benzoin ethers such as benzoin methyl ether, benzoin ethyl ether, benzoin phenyl ether; benzoin compounds such as benzoin, methyl benzoin, ethyl benzoin; benzyl compounds such as benzyl dimethyl ketal; Acridine compounds such as acridine, 1,7-bis(9,9'-acridylheptane); N-phenylglycine; and coumarin.

In the 2,4,5-triarylimidazole dimer, the substituents of the aryl groups of the two triarylimidazole moieties may be the same to provide a symmetrical compound, or different to provide an asymmetrical compound. It is also possible to combine a thioxanthone compound with a tertiary amine as in the combination of diethylthioxanthone and dimethylaminobenzoic acid.

Among these, from the viewpoint of curability, transparency, and heat resistance, the α-hydroxy ketone and the phosphine oxide are preferred. These thermal radical polymerization initiators and photoradical polymerization initiators may be used alone or in combination of two or more. Furthermore, it can also be used in combination with an appropriate sensitizer.

When the curable resin composition for forming the stretchable resin layer contains (A) a rubber component, (B) a cross-linking component, and a curing agent as the (C) component, relative to the total of the rubber component and the cross-linking component The content of the hardener (or polymerization initiator) is preferably 0.1 parts by mass to 10 parts by mass. When the content of the curing agent (or polymerization initiator) is 0.1 part by mass or more, sufficient curability tends to be easily obtained. When content of a hardening|curing agent (or a polymerization initiator) is 10 mass parts or less, there exists a tendency for sufficient light transmittance to be easily obtained. From the above viewpoints, the content of the curing agent (or polymerization initiator) is more preferably 0.3 parts by mass to 7 parts by mass, and still more preferably 0.5 parts by mass to 5 parts by mass.

The hardener may also comprise selected from the group consisting of aliphatic polyamines, polyamidoamines, polythiols, aromatic polyamines, acid anhydrides, carboxylic acids, phenol novolac resins, ester resins, and dicyandiamine at least one of them. Among these hardeners, for example, it can be used in combination with a compound (epoxy resin) having an epoxy group.

A hardening accelerator selected from a tertiary amine, an imidazole, an acid anhydride, and a phosphine type can also be added to the resin composition containing an epoxy resin as a (C)component. From the viewpoint of the storage stability and curability of the varnish, imidazole is preferably used. contained in rubber In the case of a rubber partially modified with maleic anhydride, a compatible imidazole may also be selected.

When the resin composition for forming the stretchable resin layer contains (A) a rubber component and (B) a crosslinking component, the imidazole content may be 0.1 per 100 parts by mass of the total amount of the rubber component and the crosslinking component. parts by mass to 10 parts by mass. When the content of imidazole is 0.1 part by mass or more, sufficient curability tends to be easily obtained. When the content of imidazole is 10 parts by mass or less, sufficient heat resistance tends to be easily obtained. From the above viewpoints, the content of imidazole 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) rubber component, (B) crosslinking component and (C) additive, the content of rubber component may be (A) rubber component, (B) crosslinking component. The total amount of the linking component and the (C) additive is 30% by mass to 98% by mass, 50% by mass to 97% by mass, or 60% by mass to 95% by mass on the basis of the total amount. Sufficient stretchability is easily obtained as content of a rubber component is 30 mass % or more. When the content of the rubber component is 98% by mass or less, the stretchable resin layer tends to have particularly excellent properties in terms of adhesion, insulation reliability, and heat resistance.

The stretchable resin layer or the resin composition for forming the same may further contain antioxidants, anti-yellowing agents, ultraviolet absorbers, Visible light absorbers, colorants, plasticizers, stabilizers, fillers, flame retardants, leveling agents, etc.

The stretchable resin layer can be produced, for example, by a method including dissolving or dispersing a coupling agent, a rubber component, and other components as necessary in an organic solvent to obtain a resin varnish, and applying the resin varnish to a resin varnish by a method described later. film on a conductor foil or carrier 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; tetrahydrofuran, 1,4- Cyclic ethers such as dioxane; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, 4-hydroxy-4-methyl-2-pentanone; methyl acetate, ethyl acetate , butyl acetate, methyl lactate, ethyl lactate, γ-butyrolactone and other esters; carbonates such as ethylidene carbonate and propylidene carbonate; and N,N-dimethylformamide, N,N- Dimethylacetamide, N-methylpyrrolidone and other amides. These organic solvents may be used alone or in combination of two or more. From the viewpoint of solubility and boiling point, toluene or N,N-dimethylacetamide can also be used. The concentration of the solid content (components other than the organic solvent) in the resin varnish is usually preferably 20% by mass to 80% by mass.

There is no particular limitation on the material of the carrier film, for example, polyesters such as polyethylene terephthalate (PET), polybutylene terephthalate, and polyethylene naphthalate can be listed; Polyolefins such as polyethylene and polypropylene; polycarbonate, polyamide, polyimide, polyamide imide, polyether imide, polyether sulfide, polyether sulfide, polyether ketone, polyphenylene ethers, polyphenylene sulfide, polyarylate, polysiloxane and liquid crystal polymers. Among these, from the viewpoint of flexibility and toughness, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polypropylene, polycarbonate can also be used , polyamide, polyimide, polyamide imide, polyphenylene ether, polyphenylene sulfide, polyarylate or polyamide film as carrier film.

The thickness of the carrier film is not particularly limited, but is preferably 3 μm 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 can be obtained. From the above viewpoints, the thickness is more preferably 5 μm to 200 μm, and still more preferably 7 μm to 150 μm. From the viewpoint of improving the releasability with the stretchable resin layer, a film in which the base film has been subjected to mold release treatment with a silicone-based compound, a fluorine-containing compound, or the like may be used as necessary.

If necessary, a protective film may be attached to the stretchable resin layer, and it may be used as a laminated film of 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 polyethylene and polypropylene. and other polyolefins. Among these, from the viewpoint of flexibility and toughness, polyesters such as polyethylene terephthalate and polyolefins such as polyethylene and polypropylene are preferred. From the viewpoint of improving the releasability with the stretchable resin layer, mold release treatment can also be performed using a silicone-based compound, a fluorine-containing compound, or the like.

The thickness of the protective film can be appropriately changed according to the target flexibility, and is preferably 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 viewpoints, the thickness is more preferably 15 μm to 200 μm, and still more preferably 20 μm to 150 μm.

Next, the manufacturing method of the wiring board of an embodiment is demonstrated. The wiring board of one embodiment can be produced, for example, by a method including the steps of preparing a laminate having a stretchable resin layer and a conductor foil laminated on the stretchable resin layer, and forming a through hole in the stretchable resin layer the steps of forming a copper plating layer and other plating layers on the inner wall surface of the through holes, the steps of forming an etching resist on the conductor foil, exposing the etching resist and exposing the exposed etching resist A step of developing and forming a resist pattern covering a portion of the conductor foil, a step of removing the conductor foil of a portion not covered by the resist pattern, and a step of removing the resist pattern are performed.

As a method of obtaining a laminate having a stretchable resin layer and a conductor foil, any method can be used. For example, there are a method of applying a varnish of a resin composition for forming a stretchable resin layer on the conductor foil, and a method using a vacuum A method of laminating a conductor foil on a stretchable resin layer formed on a carrier film by a press, a laminator, or the like. When the resin composition for forming a stretchable resin layer contains a crosslinking component, the stretchable resin layer is formed by advancing the crosslinking reaction (hardening reaction) of the crosslinking component by heating or light irradiation.

As a method of laminating the stretchable resin on the carrier film on the conductor foil, any method may be used, and for example, a roll laminator, a vacuum laminator, a vacuum press, or the like can be used. From the viewpoint of production efficiency, lamination is preferably 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 μm to 1000 μm. Within the above range, sufficient strength of the stretchable base material is easily obtained, and since drying is sufficiently performed, the amount of residual solvent in the resin film can be reduced.

The conductor foil may be further laminated on the surface on the opposite side of the conductor foil of the elastic resin layer, thereby producing a laminate in which the conductor foil is formed on both surfaces of the elastic resin layer. By providing conductor foils on both surfaces of the stretchable resin layer, the warpage of the laminate during curing can be suppressed.

The formation of the through hole can be easily formed by drilling processing or laser processing. In the drilling process, a through hole shape can be formed. On the other hand, in addition to the shape of the through via hole, the shape of a blind via (blind via) can also be formed in the laser processing, which can further improve the margin of the wiring design.

Preferably, drilling processing or laser processing is selected according to the shape and diameter of the through hole. When forming a through hole, it is preferable to use a drilling process, and when forming a non-penetrating blind hole shape, it is preferable to use a laser process.

Plating layers, such as a copper plating layer, can be formed by a well-known method. For example, a process of applying a plating catalyst for adhering palladium to the inner wall surface of the through hole is performed, and then immersed in an electroless plating solution to deposit an electroless plating layer having a thickness of 0.3 μm to 1.5 μm on the entire inner wall surface of the through hole. (conductor layer). If necessary, electroplating (electroplating) can be further performed and adjusted to a desired thickness. As the electroless plating liquid used for the electroless plating, a known electroless plating liquid can be used, and is not particularly limited. In addition, a well-known method can also be used for electrolytic plating, and is not particularly limited. As these platings (electroless plating, electrolytic plating), copper plating is preferable from the viewpoint of cost and resistance value.

As a method of forming a wiring pattern on a conductor foil of a laminated board (a laminated board for forming a wiring board), a method using generally etching or the like can be used. For example, when using copper foil as a conductor foil, as an etching liquid, the mixed solution of concentrated sulfuric acid and hydrogen peroxide water, a ferric chloride solution, etc. can be used, for example. Furthermore, the land portion around the through hole may be formed together with the wiring pattern.

As an etching resist used for etching, for example, Photec H-7025 (manufactured by Hitachi Chemical Co., Ltd., trade name), Photec H-7030 (Hitachi Chemical Co., Ltd.) manufacture, trade name), and X-87 (TAIYO HOLDINGS (stock) manufacture, trade name). After the formation of the wiring pattern, the etching resist is usually removed.

A stretchable element can be obtained by mounting various electronic devices on a wiring board. [Example]

The present disclosure will be further specifically described with reference to the following reference examples. However, the present disclosure is not limited to these reference examples.

Study 1 1-1. Preparation of Varnish for Stretch Resin Layer Formation [Resin Varnish A] Hydrogenated styrene butadiene rubber (manufactured by Asahi Kasei Co., Ltd., Tuftec P1500) as the component (A) was used , trade name) 30 g, and 70 g of toluene were mixed with stirring to obtain resin varnish A. [Resin Varnish B] 20 g of hydrogenated styrene butadiene rubber (manufactured by JSR Corporation, Dynaron 2324P, trade name) as component (A), butanediol as component (B) Acrylate (manufactured by Hitachi Chemical Co., Ltd., Fancryl FA-124AS, trade name) 5 g, and bis(2,4,6-trimethylbenzyl)benzene as component (C) 0.4 g of phosphine oxide (manufactured by BASF Co., Ltd., Irgacure 819, trade name) and 15 g of toluene as a solvent were mixed with stirring to obtain resin varnish B. [Resin Varnish C] 20 g of an acrylic polymer (manufactured by Kuraray Co., Ltd., KURARITY LA2140, trade name) as a component (A), an aliphatic chain modified ring as a component (B) Oxygen resin (manufactured by DIC Co., Ltd., EXA4816, trade name) 5 g, and 2-phenylimidazole as component (C) (manufactured by Shikoku Chemical Co., Ltd., 2PZ, trade name) 0.5 g, And 15 g of methyl ethyl ketone as a solvent was mixed, stirring, and resin varnish C was obtained. [Resin Varnish D] 25.0 g of methyl ethyl ketone was mixed with 50 g of biphenyl aralkyl type epoxy resin (manufactured by Nippon Kayaku Co., Ltd., NC-3000H, trade name). To this was added 20 g of a phenol novolak-type phenol resin (manufactured by DIC Co., Ltd., TD2131, trade name), and further added 2-phenylimidazole (manufactured by Shikoku Chemical Industry Co., Ltd.) as a hardening accelerator. 2PZ, trade name) 0.15 g. Then, it diluted with methyl ethyl ketone, and resin varnish D was obtained.

1-2. Reference Example for Production of Laminate with Conductor Layer 1-1 [Laminated Film with Stretchable Resin Layer] Preparation of a release-treated polyethylene terephthalate (PET) film (Teijin DuPont film) "Purex A31" manufactured by Films (stock), thickness 25 μm) was used as the carrier film. The resin varnish A was apply|coated to the mold release process surface of this PET film using a knife coater ("SNC-350" by Yasui Seiki Co., Ltd.). The coating film was dried at 100° C. for 20 minutes in a dryer (“MSO-80TPS” manufactured by Futaba Science Co., Ltd.) to form a stretchable resin layer having a thickness of 100 μm after coating. On the formed stretchable resin layer, a release-treated PET film similar to that of the carrier film was attached as a protective film so that the release-treated surface became the stretchable resin layer side, and a laminated film A was obtained. [Laminated Board with Conductive Layer] The protective film of the laminated film A was peeled off, and the stretchable resin layer of the laminated film A was superimposed on the roughened surface side of copper foil (manufactured by Nippon Electron 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 pressing time of 60 seconds to produce a tape conductor. layered laminate.

Reference Example 1-2 Resin varnish A was changed to resin varnish B, and copper foil was changed to another copper foil (manufactured by JX Metals Co., Ltd., BHY-82F-HA-V2-12 μm, trade name), except that Other than that, it carried out similarly to Reference Example 1-1, and obtained the laminated body which has copper foil and an uncured resin layer. Then, 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.), thereby obtaining a laminate.

Reference example 1-3 Except having changed resin varnish A to resin varnish C, it carried out similarly to Reference example 1-1, and obtained the laminated body which has copper foil and an uncured resin layer. Then, the resin layer was hardened on the conditions of 180 degreeC and 1 hour using a dryer, and the laminated board with a conductor layer was obtained.

Comparative Reference Example 1-1 Except having changed the resin varnish A to the resin varnish D, it carried out similarly to the reference example 1-1, and obtained the laminated body which has a copper foil and an uncured resin layer. Then, the resin layer was hardened on the conditions of 180 degreeC and 1 hour using a dryer, and the laminated board with a conductor layer was obtained.

[Preparation and Evaluation of Wiring Board] As shown in FIG. 3 , a test wiring board having a stretchable resin layer 3 and a conductor foil 5 having a wave pattern formed on the stretchable resin layer 3 as a conductor layer was produced 1. First, an etching resist (manufactured by Hitachi Chemical Co., Ltd., Photec RY-5325, trade name) was attached to the conductor layer of each laminate board with a conductor layer by a roll laminator, and then A photo tool on which a wave pattern is formed in close contact. The etching resist was exposed to an energy of 50 mJ/cm ² using an EXM-1201 exposure machine manufactured by ORC Corporation. Next, spray development was performed for 240 seconds with a 1 mass % sodium carbonate aqueous solution at 30° C. to dissolve the unexposed portion of the etching resist, thereby forming a resist pattern having a wavy shape. Next, the copper foil of the part not covered with the resist pattern is removed with an etchant. After that, the etching resist was removed with a stripping solution to obtain a wiring board 1 having a conductor foil 5 formed on the stretchable resin layer 3 with a wiring pattern having a wiring width of 50 μm and a wavy wiring pattern meandering in the predetermined direction X. The obtained wiring board was stretched and deformed in the X direction until the strain was 10%, and the stretchable resin layer and the corrugated wiring pattern at the time of returning to the original state were observed. Regarding the stretchable resin layer and the wiring pattern, the case where no breakage occurred during extension was referred to as "A", and the case where the breakage occurred was referred to as "C".

[Table 1]

Table 1 shows the evaluation results of Reference Examples 1-1 to 1-3 and Comparative Reference Example 1-1. In the wiring boards having the wavy wiring patterns formed of the laminates with conductor layers of Reference Examples 1-1 to 1-3, it was found that the stretchable resin layer did not break even when stretched by 10%. There is also no problem with the appearance of the wave-shaped wiring pattern. On the other hand, in Comparative Reference Example 1-1, it was found that the resin layer did not have stretchability, so the resin layer was broken before being stretched by 10%, and the wiring was also broken at the same time. By providing through-holes in the wiring boards formed of the laminates with conductor layers of the reference examples 1-1 to 1-3 described above, it is possible to obtain wirings having high elasticity and enabling interlayer connection at the time of lamination substrate.

Study 2 Reference Example 2-1 [Resin Varnish] 10 g of maleic anhydride-modified styrene ethylene butadiene rubber (manufactured by Kraton Co., Ltd., FG1924GT, trade name) as the component (A) was prepared as (B) 2.5 g of dicyclopentadiene-type epoxy resin (manufactured by DIC Co., Ltd., EPICLON HP7200H, trade name), and (C) component (hardening accelerator) 0.38 g of 1-benzyl-2-methylimidazole (manufactured by Shikoku Chemical Co., Ltd., 1B2MZ, trade name) and 50 g of toluene were mixed with stirring to obtain a resin varnish.

[Laminated film] A release-treated polyethylene terephthalate (PET) film (“Purex A31” manufactured by Teijin DuPont Films Co., Ltd., thickness 25 μm) was prepared as carrier film. The said resin varnish was apply|coated to the mold release process surface of this PET film using the knife coater ("SNC-350" by Yasui Seiki Co., Ltd.). The coating film was heated and dried at 100° C. for 20 minutes in a dryer (“MSO-80TPS” manufactured by Futaba Science Co., Ltd.) to form a resin layer with a thickness of 100 μm. On the formed resin layer, the same release-treated PET film as the carrier film was attached as a protective film so that the release-treated surface became the resin layer side to obtain a laminated film.

[Preparation of conductor substrate] The protective film of the laminate film was peeled off, and on the exposed resin layer, an electrolytic copper foil (Furukawa) having a roughened surface with a surface roughness Ra of 1.5 μm was superimposed on the exposed resin layer with the roughened surface facing the resin layer side. Electrical Industry (Stock) Manufacturing, F2-WS-12, trade name). In this state, using a vacuum pressurized laminator (“V130” manufactured by Nikko-Materials Co., Ltd.), the electrolytic copper was laminated under the conditions of a pressure of 0.5 MPa, a temperature of 90°C, and a pressurization time of 60 seconds. The foil is laminated on the resin layer. Then, by heating at 180°C for 60 minutes in a dryer ("MSO-80TPS" manufactured by Futaba Science Co., Ltd.), a stretchable resin layer having a cured product as a resin layer and an electrolytic copper foil were obtained. conductor substrate.

Reference Example 2-2 10 g of maleic anhydride-modified styrene ethylene butadiene rubber (manufactured by Kraton Co., Ltd., FG1924GT, trade name) as component (A), two Cyclopentadiene epoxy resin (manufactured by DIC Co., Ltd., EPICLON HP7200H, trade name) 2.5 g, 1-benzyl-2 as component (C) (hardening accelerator) - Methylimidazole (manufactured by Shikoku Chemical Co., Ltd., 1B2MZ, trade name) 0.38 g, phenolic antioxidant (manufactured by ADEKA, Inc., AO-60, trade name) 0.1 g, and phosphorous acid Antioxidant (made by ADEKA Co., Ltd., 2112, trade name) 0.1 g and 50 g of toluene were mixed with stirring to obtain a resin varnish. Using the obtained resin varnish, it carried out similarly to Reference Example 2-1, and produced the laminated film which has a resin layer, and a conductor substrate.

Evaluation [Heat Resistance Test] The laminate film was heated at 180° C. for 60 minutes to harden the resin layer to form a stretchable resin layer. After removing the carrier film and the protective film, the stretchable resin layer was subjected to heat treatment using a nitrogen reflow system (manufactured by Tamura Co., Ltd., TNV-EN) using the temperature distribution shown in Fig. 4 in accordance with IPC/JEDEC J-STD-020 heat resistance test. The elongation and tensile elastic 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 Elasticity Coefficient and Elongation at Break] A test piece of an elongated stretchable resin layer having a length of 40 mm and a width of 10 mm was prepared. This test piece was subjected to a tensile test using an autograph (“EZ-S” manufactured by Shimadzu Corporation) to obtain a stress-strain curve. From the obtained stress-strain curve, the tensile modulus of elasticity and the elongation at break were determined. The tensile test was performed under the conditions of a distance between the grips 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 stress 0.5 N to 1.0 N. The strain at the time point when the test piece broke was recorded as the elongation at break.

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

[Viscosity] The laminated film was heated at 180° C. for 60 minutes to harden the resin layer to form a stretchable resin layer. The carrier film and the protective film were removed from the cured laminated film, and a test piece of the laminated film with a length of 70 mm and a width of 20 mm was prepared. The viscosity of the surface of the exposed resin layer was measured using the viscosity tester ("TACII" by Rhesca Corporation). The measurement conditions were set to constant load mode, immersion speed of 120 mm/min, test speed of 600 mm/min, load of 100 gf, load holding time of 1 s, and temperature of 30°C.

[Table 2]

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 copper foil even after the heat resistance test. In addition, the viscosity of the resin layer is moderately low, and the handleability of the resin layer is also excellent. By forming wiring patterns and through-holes on the conductor substrates of Reference Example 2-1 to Reference Example 2-2, high elasticity and interlayer connection can be achieved during lamination, and even after the heat resistance test. Excellent stretchability and excellent adhesion between the copper foil and the stretchable resin layer can be maintained, and a wiring board having a moderately low viscosity of the stretchable resin layer can be obtained.

1‧‧‧Wiring board 3‧‧‧Stretchable resin layer 5‧‧‧Conductor foil 10‧‧‧Stretchable resin layer 20‧‧‧Conductor foil 30‧‧‧Through hole 40‧‧‧Electroless copper plating layer 50 ‧‧‧Land 100‧‧‧Wiring Board D‧‧‧Diameter (Aperture) W‧‧‧Width X‧‧‧Direction

FIG. 1 is a cross-sectional view showing an embodiment of a wiring board. FIG. 2 is a stress-strain curve showing a measurement example of the recovery rate. FIG. 3 is a plan view showing an embodiment of a wiring board. FIG. 4 is a graph showing a temperature profile of a heat resistance test.

10‧‧‧Stretchable resin layer

20‧‧‧Conductor foil

30‧‧‧Through hole

40‧‧‧Electroless copper plating

50‧‧‧Connecting plate part

100‧‧‧Wiring board

D‧‧‧diameter (diameter)

W‧‧‧Width

Claims (13)

A wiring board, comprising: a stretchable resin layer; a conductor foil provided on the stretchable resin layer and forming a wiring pattern; and a through hole provided in the stretchable resin layer; the stretchable resin layer comprising a (A) A hardened product of a resin composition of a rubber component and (B) a cross-linking component, wherein the (A) rubber component contains a rubber having a cross-linking group, and the (B) cross-linking component is a cross-linking component having a group selected from (methyl) ) At least one reactive group in the group consisting of acrylic group, vinyl group, epoxy group, styryl group, amine group, isocyanurate group, urea group, cyanate group, isocyanate group, and mercapto group compound of. The wiring board according to claim 1, wherein the conductor foil is a copper foil. The wiring substrate according to claim 1 or claim 2, wherein the through hole is formed by laser or drilling. The wiring board according to claim 1 or claim 2, wherein the diameter of the through hole is 10 μm to 500 μm. The wiring board according to claim 1 or claim 2, further comprising: a copper plating layer provided on the inner wall surface of the through hole. The wiring board according to claim 5, further comprising: a land portion provided around the through hole on the stretchable resin layer, In addition, in connection with the copper plating layer, the width of the land portion from the end face of the through hole is 10 μm or more. The wiring board according to claim 1 or claim 2, wherein the (A) rubber component comprises a rubber component selected from the group consisting of acrylic rubber, isoprene rubber, butyl rubber, styrene butadiene rubber, butadiene rubber Composed of vinyl rubber, acrylonitrile butadiene rubber, silicone rubber, urethane rubber, chloroprene rubber, ethylene propylene rubber, fluorine rubber, vulcanized rubber, epichlorohydrin rubber, and chlorobutyl rubber at least one of the groups. The wiring board according to claim 1 or claim 2, wherein the crosslinking group is at least one of an acid anhydride group and a carboxyl group. The wiring board according to claim 1 or claim 2, wherein the resin composition further contains (C) at least one of a curing agent and a curing accelerator. The wiring board according to claim 1 or claim 2, wherein the content of the (A) rubber component is 30% by mass to 100% by mass relative to 100% by mass of the stretchable resin layer. A manufacturing method of a wiring board for manufacturing the wiring board according to any one of claims 1 to 10 of the scope of application, the manufacturing method of the wiring board comprising: preparing a resin layer having a stretchability and laminating on a the step of forming a laminate of conductor foils on the stretchable resin layer; the step of forming through holes in the stretchable resin layer; the step of forming an etching resist on the conductor foil; the step of exposing the etching resist and developing the exposed etching resist to form a resist pattern covering a part of the conductor foil; a step of removing part of the conductor foil; and a step of removing the resist pattern. The method according to claim 11, further comprising the step of forming a copper plating layer on the inner wall surface of the through hole after the step of forming the through hole in the stretchable resin layer. A stretchable element comprising: the wiring substrate according to any one of the first to tenth claims in the scope of application, and an electronic device mounted on the wiring substrate.

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