printed wiring board

Abstract

To provide a printed wiring board and so forth in which the shape of a via hole has a suppressed step.SOLUTION: A printed wiring board comprises in the following order: a resin layer having a first surface; an insulation layer which is in contact with the first surface of the resin layer, and which includes a cured product of a resin composition; and an inner layer circuit board. The printed wiring board further comprises a via hole which penetrates the resin layer and the insulation layer in the thickness direction. When a top diameter of the via hole is defined as a (μm), and a distance from an end of the first surface inside the via hole to an end of a contact surface between the first surface and the insulation layer is defined as d (μm), then the following relationship is satisfied: [d / {(1 / 2)×a}]×100≤5.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a printed wiring board, a method for producing the same, and a resin composition and a resin sheet used to form an insulating layer of the printed wiring board. [Background technology]

[0002] In recent years, there has been an increasing need for substrates that require high-frequency characteristics by using insulating materials with excellent electrical properties, such as modified polyimides or liquid crystal polymers. Laminating modified polyimides or liquid crystal polymers requires high-temperature processing. Therefore, it is common to use a thermosetting resin as a bonding sheet, forming a two-layer structure consisting of the bonding sheet and an insulating material with excellent electrical properties, such as modified polyimides or liquid crystal polymers. Many such bonding sheets have been developed, including the resin compositions described in Patent Document 1, for example. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-59779 Summary of the Invention [Problem to be solved by the invention]

[0004] In recent years, in order to improve the electrical properties of printed wiring boards, layers of modified polyimides or liquid crystal polymers have been laminated onto inner layer circuit boards. Laminating such layers as a single layer generally requires processing under high temperature conditions. Therefore, lamination is often performed using an insulating layer that functions as a bonding sheet. A bonding sheet is an adhesive sheet that is placed between each layer of a multilayer structure to bond the layers together and also functions as an insulating layer to insulate the layers from each other.

[0005] When manufacturing a printed wiring board, a via hole may be formed in an insulating layer, a layer of modified polyimide, etc. The term "via hole" generally refers to a hole that penetrates the insulating layer, the layer of modified polyimide, etc. A method using a laser can be considered as a method for forming the via hole.

[0006] The present inventors have found that laser irradiation generates heat, which can cause interfacial peeling between the insulating layer and the layer of modified polyimide or the like, or further erosion of the resin surrounding the via hole in the insulating layer, resulting in a step in the cross-sectional shape of the via hole near the interface between the insulating layer and the layer of modified polyimide or the like. Furthermore, while a desmear treatment is typically performed after the formation of a via hole, the inventors have found that the degree of roughening of the surface of each layer varies depending on the components contained in each layer, and therefore, performing the desmear treatment can result in a step in the cross-sectional shape of the via hole near the interface between the insulating layer and the layer of modified polyimide or the like. If this step is large, the reliability of the electrical connection may be reduced.

[0007] An object of the present invention is to provide a printed wiring board in which the step in the shape of a via hole is suppressed; a method for producing the same; and a resin composition and a resin sheet used for forming an insulating layer of the printed wiring board. [Means for solving the problem]

[0008] That is, the present invention includes the following. [1] A printed wiring board comprising, in this order, a resin layer having a first surface, an insulating layer in contact with the first surface of the resin layer and including a cured product of a resin composition, and an inner layer circuit board, a via hole penetrating the resin layer and the insulating layer in the thickness direction; The top diameter of the via hole is a (μm), When the distance from the end of the first surface in the via hole to the end of the contact surface between the first surface and the insulating layer is d (μm), A printed wiring board that satisfies the relationship [d / {(1 / 2)×a}]×100≦5. [2] The printed wiring board according to [1], wherein the top diameter of the via hole is 50 μm or less. [3] The printed wiring board according to [1] or [2], wherein the resin composition contains an inorganic filler. [4] The printed wiring board according to [3], wherein the content of the inorganic filler is 50% by mass or less when the non-volatile components of the resin composition are 100% by mass. [5] The printed wiring board according to any one of [1] to [4], wherein the resin composition has a coefficient of linear thermal expansion of 40 ppm or less after curing. [6] The printed wiring board according to any one of [1] to [5], wherein the resin layer is formed of a thermoplastic resin. [7] The printed wiring board according to any one of [1] to [6], wherein the resin layer contains either a polyimide resin or a liquid crystal polymer. [8] A resin composition containing an inorganic filler, A resin composition for bonding sheets, in which the content of an inorganic filler is 50% by mass or less when the nonvolatile components in the resin composition are taken as 100% by mass. [9] A resin sheet comprising a support and a resin composition layer formed on the support from the resin composition according to [8].

[10] (A) A step of forming a resin layer on the surface of the resin composition layer of the resin sheet according to [9] that is not bonded to the support; (B) a step of laminating a resin sheet having a resin layer formed thereon on an inner layer circuit board and curing the resin composition layer to form an insulating layer; (C) a step of performing a plasma treatment on the surface of the resin layer to form via holes penetrating the resin layer and the insulating layer; (D) a roughening treatment step, and (E) A method for producing a printed wiring board, comprising the step of forming a conductor layer on the surface of a resin layer. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a printed wiring board in which the step in the shape of a via hole is suppressed, a method for producing the same, and a resin composition and a resin sheet used for forming an insulating layer of a printed wiring board. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a cross-sectional view schematically showing a printed wiring board according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0011] The present invention will be described in detail below with reference to embodiments and examples. However, the present invention is not limited to the embodiments and examples described below, and can be implemented with any modifications within the scope of the claims of the present invention and their equivalents.

[0012] Before describing the printed wiring board of the present invention and the method for producing the same, a resin composition used to form the insulating layer of the printed wiring board and a resin sheet used in producing the printed wiring board will be described.

[0013] [Resin composition] The cured product of the resin composition used to form the insulating layer can function as an insulating layer as well as a bonding sheet that bonds an inner layer circuit board and the resin layer. Therefore, the resin composition can be used as a bonding sheet.

[0014] The resin composition may be any composition as long as the cured product has sufficient insulating properties and adhesive properties. Examples of such resin compositions include a composition containing (a) a curable resin. In addition to component (a), the resin composition may further contain, as necessary, (b) an inorganic filler, (c) a curing accelerator, (d) a thermoplastic resin, (e) an elastomer, and (f) other additives. Each component contained in the resin composition will be described in detail below.

[0015] <(a) Curing resin> The resin composition contains (a) a curable resin. Examples of the (a) curable resin include thermosetting resins and photocurable resins, but thermosetting resins that can be used to form insulating layers for printed wiring boards are preferred.

[0016] Examples of thermosetting resins include epoxy resins, phenolic resins, naphthol resins, benzoxazine resins, active ester resins, cyanate ester resins, carbodiimide resins, amine resins, and acid anhydride resins. The component (a) may be used singly or in any combination of two or more types in any ratio. Hereinafter, resins that can react with epoxy resins to cure the resin composition, such as phenolic resins, naphthol resins, benzoxazine resins, active ester resins, cyanate ester resins, carbodiimide resins, amine resins, and acid anhydride resins, may be collectively referred to as "curing agents." From the viewpoint of forming an insulating layer, the resin composition preferably contains an epoxy resin and a curing agent as component (a), more preferably an epoxy resin, active ester resin, cyanate ester resin, or phenolic resin, and even more preferably an epoxy resin, cyanate ester resin, or active ester resin.

[0017] Examples of epoxy resins for component (a) include bixylenol-type epoxy resins, bisphenol A-type epoxy resins, bisphenol F-type epoxy resins, bisphenol S-type epoxy resins, bisphenol AF-type epoxy resins, dicyclopentadiene-type epoxy resins, trisphenol-type epoxy resins, naphthol novolac-type epoxy resins, phenol novolac-type epoxy resins, tert-butyl-catechol-type epoxy resins, naphthalene-type epoxy resins, naphthol-type epoxy resins, anthracene-type epoxy resins, glycidylamine-type epoxy resins, glycidyl ester-type epoxy resins, cresol novolac-type epoxy resins, biphenyl-type epoxy resins, linear aliphatic epoxy resins, epoxy resins having a butadiene structure, alicyclic epoxy resins, heterocyclic epoxy resins, spiro ring-containing epoxy resins, cyclohexane-type epoxy resins, cyclohexanedimethanol-type epoxy resins, naphthylene ether-type epoxy resins, trimethylol-type epoxy resins, and tetraphenylethane-type epoxy resins. The epoxy resins may be used alone or in combination of two or more.

[0018] The resin composition preferably contains, as component (a), an epoxy resin having two or more epoxy groups per molecule. From the viewpoint of significantly achieving the desired effects of the present invention, the proportion of the epoxy resin having two or more epoxy groups per molecule relative to 100% by mass of the non-volatile components of component (a) is preferably 50% by mass or more, more preferably 60% by mass or more, and particularly preferably 70% by mass or more.

[0019] Epoxy resins include epoxy resins that are liquid at a temperature of 20°C (hereinafter sometimes referred to as "liquid epoxy resins") and epoxy resins that are solid at a temperature of 20°C (hereinafter sometimes referred to as "solid epoxy resins"). The resin composition may contain only a liquid epoxy resin or only a solid epoxy resin as component (a), but from the viewpoint of significantly achieving the effects of the present invention, it is preferable to contain a combination of a liquid epoxy resin and a solid epoxy resin.

[0020] The liquid epoxy resin is preferably a liquid epoxy resin having two or more epoxy groups in one molecule.

[0021] Preferred liquid epoxy resins include bisphenol A type epoxy resins, bisphenol F type epoxy resins, bisphenol AF type epoxy resins, naphthalene type epoxy resins, glycidyl ester type epoxy resins, glycidyl amine type epoxy resins, phenol novolac type epoxy resins, alicyclic epoxy resins having an ester skeleton, cyclohexane type epoxy resins, cyclohexane dimethanol type epoxy resins, glycidyl amine type epoxy resins, and epoxy resins having a butadiene structure, with cyclohexane type epoxy resins being more preferred.

[0022] Specific examples of liquid epoxy resins include "HP4032," "HP4032D," and "HP4032SS" (naphthalene-type epoxy resins) manufactured by DIC Corporation; "828US," "jER828EL," "825," and "Epikote 828EL" (bisphenol A-type epoxy resins) manufactured by Mitsubishi Chemical Corporation; "jER807" and "1750" (bisphenol F-type epoxy resins) manufactured by Mitsubishi Chemical Corporation; "jER152" (phenol novolac-type epoxy resin) manufactured by Mitsubishi Chemical Corporation; and "630" and "630LSD" (glycidylamine-type epoxy resins) manufactured by Mitsubishi Chemical Corporation. ); "ZX1059" manufactured by Nippon Steel Chemical & Material Co., Ltd. (a mixture of bisphenol A type epoxy resin and bisphenol F type epoxy resin); "EX-721" manufactured by Nagase ChemteX Corporation (a glycidyl ester type epoxy resin); "Celloxide 2021P" manufactured by Daicel Corporation (an alicyclic epoxy resin having an ester skeleton); "PB-3600" manufactured by Daicel Corporation (an epoxy resin having a butadiene structure); and "ZX1658" and "ZX1658GS" (liquid 1,4-glycidylcyclohexane type epoxy resin) manufactured by Nippon Steel Chemical & Material Co., Ltd. These may be used alone or in combination of two or more.

[0023] As the solid epoxy resin, a solid epoxy resin having three or more epoxy groups in one molecule is preferred, and an aromatic solid epoxy resin having three or more epoxy groups in one molecule is more preferred.

[0024] Preferred solid epoxy resins include bixylenol-type epoxy resins, naphthalene-type epoxy resins, naphthalene-type tetrafunctional epoxy resins, cresol novolac-type epoxy resins, dicyclopentadiene-type epoxy resins, trisphenol-type epoxy resins, naphthol-type epoxy resins, biphenyl-type epoxy resins, naphthylene ether-type epoxy resins, anthracene-type epoxy resins, bisphenol A-type epoxy resins, bisphenol AF-type epoxy resins, and tetraphenylethane-type epoxy resins, and more preferred are bixylenol-type epoxy resins, naphthalene-type epoxy resins, bisphenol AF-type epoxy resins, and naphthylene ether-type epoxy resins.

[0025] Specific examples of solid epoxy resins include "HP4032H" (naphthalene-type epoxy resin), "HP-4700", "HP-4710" (naphthalene-type tetrafunctional epoxy resin), "N-690" (cresol novolac-type epoxy resin), "N-695" (cresol novolac-type epoxy resin), "HP-7200", "HP-7200HH", "HP-7200H" (dicyclopentadiene-type epoxy resin), "EXA-7311", "EXA-7311-G3", "EXA-7311-G4", "EXA-7311-G4S", and "HP6000" (naphthylene ether-type epoxy resin), manufactured by DIC Corporation; and "EPPN-502H" (trisphenol-type epoxy resin), "NC7000L" (naphthol novolac-type epoxy resin), "NC3000H", and "NC30 00, "NC3000L," and "NC3100" (biphenyl-type epoxy resins); "ESN475V" (naphthalene-type epoxy resin) and "ESN485" (naphthol novolac-type epoxy resin) manufactured by Nippon Steel Chemical & Material Co., Ltd.; "YX4000H," "YL6121" (biphenyl-type epoxy resin), "YX4000HK" (bixylenol-type epoxy resin), and "YX8800" (anthracene-type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "PG-100" and "CG-500" manufactured by Osaka Gas Chemicals Co., Ltd.; "YL7760" (bisphenol AF-type epoxy resin), "YL7800" (fluorene-type epoxy resin), "jER1010" (solid bisphenol A-type epoxy resin), and "jER1031S" (tetraphenylethane-type epoxy resin) manufactured by Mitsubishi Chemical Corporation. These may be used alone or in combination of two or more.

[0026] When a liquid epoxy resin and a solid epoxy resin are used in combination as component (a), the ratio by mass between them (liquid epoxy resin:solid epoxy resin) is preferably 1:0.1 to 1:20, more preferably 1:1 to 1:15, and particularly preferably 1:5 to 1:10. When the ratio between the liquid epoxy resin and the solid epoxy resin is within this range, the desired effects of the present invention can be significantly achieved. Furthermore, when used in the form of a resin sheet, appropriate adhesiveness is usually imparted. Furthermore, when used in the form of a resin sheet, sufficient flexibility is usually obtained, improving handleability. Furthermore, a cured product having sufficient breaking strength can usually be obtained.

[0027] The epoxy equivalent of the epoxy resin as component (a) is preferably 50 g / eq. to 5000 g / eq., more preferably 50 g / eq. to 3000 g / eq., even more preferably 80 g / eq. to 2000 g / eq., and even more preferably 110 g / eq. to 1000 g / eq. By keeping it within this range, a cured product of the resin composition can be obtained with sufficient crosslink density. The epoxy equivalent is the mass of the epoxy resin containing one equivalent of epoxy groups. This epoxy equivalent can be measured according to JIS K7236.

[0028] From the viewpoint of significantly achieving the desired effects of the present invention, the weight average molecular weight (Mw) of the epoxy resin as component (a) is preferably 100 to 5000, more preferably 250 to 3000, and even more preferably 400 to 1500. The weight average molecular weight of the epoxy resin is a weight average molecular weight in terms of polystyrene measured by gel permeation chromatography (GPC).

[0029] The content of the epoxy resin as component (a) is preferably 10% by mass or more, more preferably 30% by mass or more, and even more preferably 40% by mass or more, based on 100% by mass of the nonvolatile components in the resin composition, from the viewpoint of obtaining a cured product exhibiting good mechanical strength and insulation reliability. The upper limit of the epoxy resin content is preferably 70% by mass or less, more preferably 60% by mass or less, and even more preferably 50% by mass or less, from the viewpoint of significantly achieving the desired effects of the present invention. In the present invention, the content of each component in the resin composition is the value based on 100% by mass of the nonvolatile components in the resin composition, unless otherwise specified.

[0030] The content of the epoxy resin as component (a) is preferably 10% by mass or more, more preferably 30% by mass or more, and even more preferably 40% by mass or more, based on 100% by mass of the resin component in the resin composition, from the viewpoint of significantly achieving the effects of the present invention. The upper limit of the epoxy resin content is preferably 90% by mass or less, more preferably 80% by mass or less, even more preferably 75% by mass or less, 70% by mass or less, 60% by mass or less, or 50% by mass or less, from the viewpoint of significantly achieving the desired effects of the present invention. Unless otherwise specified, the resin component refers to the non-volatile components in the resin composition excluding (b) the inorganic filler.

[0031] The active ester resin used as component (a) may be a resin having one or more active ester groups per molecule. Among these, preferred active ester resins are those having two or more highly reactive ester groups per molecule, such as phenol esters, thiophenol esters, N-hydroxyamine esters, and esters of heterocyclic hydroxy compounds. The active ester resin is preferably one obtained by a condensation reaction between a carboxylic acid compound and / or a thiocarboxylic acid compound and a hydroxy compound and / or a thiol compound. In particular, from the viewpoint of improving heat resistance, active ester resins obtained from a carboxylic acid compound and a hydroxy compound are preferred, and active ester resins obtained from a carboxylic acid compound and a phenol compound and / or a naphthol compound are more preferred.

[0032] Examples of the carboxylic acid compound include benzoic acid, acetic acid, succinic acid, maleic acid, itaconic acid, phthalic acid, isophthalic acid, terephthalic acid, and pyromellitic acid.

[0033] Examples of phenol compounds or naphthol compounds include hydroquinone, resorcinol, bisphenol A, bisphenol F, bisphenol S, phenolphthalene, methylated bisphenol A, methylated bisphenol F, methylated bisphenol S, phenol, o-cresol, m-cresol, p-cresol, catechol, α-naphthol, β-naphthol, 1,5-dihydroxynaphthalene, 1,6-dihydroxynaphthalene, 2,6-dihydroxynaphthalene, dihydroxybenzophenone, trihydroxybenzophenone, tetrahydroxybenzophenone, phloroglucin, benzenetriol, dicyclopentadiene-type diphenol compounds, and phenol novolak. Here, "dicyclopentadiene-type diphenol compounds" refers to diphenol compounds obtained by condensing one dicyclopentadiene molecule with two phenol molecules.

[0034] Preferred examples of the active ester resin include active ester resins containing a dicyclopentadiene-type diphenol structure, active ester resins containing a naphthalene structure, active ester resins containing an acetylated product of phenol novolac, and active ester resins containing a benzoylated product of phenol novolac. Among these, active ester resins containing a naphthalene structure and active ester resins containing a dicyclopentadiene-type diphenol structure are more preferred. The "dicyclopentadiene-type diphenol structure" refers to a divalent structural unit consisting of phenylene-dicyclopentylene-phenylene.

[0035] Commercially available activated ester resins include "EXB9451," "EXB9460," "EXB9460S," "HPC-8000-65T," "HPC-8000H-65TM," and "EXB-8000L-65TM" (manufactured by DIC Corporation) as activated ester resins containing a dicyclopentadiene-type diphenol structure; and "EXB9416-70BK," "EXB-8100L-65T," "EXB-8150L-65T," "EXB-8150-65T," "HPC-8150-60T," "HPC-8150-62T," "HPB-8151-62T" (manufactured by DIC Corporation) as naphthalene-type activated ester resins containing a naphthalene structure. 65T" (manufactured by Air Water Inc.); an activated ester resin containing acetylated phenol novolac is "DC808" (manufactured by Mitsubishi Chemical Corporation); an activated ester resin containing benzoated phenol novolac is "YLH1026" (manufactured by Mitsubishi Chemical Corporation); an activated ester resin which is an acetylated phenol novolac is "DC808" (manufactured by Mitsubishi Chemical Corporation); activated ester resins which are benzoated phenol novolac are "YLH1026" (manufactured by Mitsubishi Chemical Corporation), "YLH1030" (manufactured by Mitsubishi Chemical Corporation), "YLH1048" (manufactured by Mitsubishi Chemical Corporation); and "EXB-8500-65T" (manufactured by DIC Corporation).

[0036] From the viewpoint of significantly achieving the effects of the present invention, the content of the active ester resin as component (a) is preferably 1% by mass or more, more preferably 2% by mass or more, and even more preferably 4% by mass or more, relative to 100% by mass of the non-volatile components in the resin composition, and is preferably 20% by mass or less, more preferably 15% by mass or less, and even more preferably 10% by mass or less.

[0037] From the viewpoint of significantly achieving the effects of the present invention, the content of the active ester resin as component (a) is preferably 3% by mass or more, more preferably 5% by mass or more, and even more preferably 8% by mass or more, and is preferably 25% by mass or less, more preferably 20% by mass or less, and even more preferably 15% by mass or less, when the resin component in the resin composition is taken as 100% by mass.

[0038] As the phenolic resin and naphtholic resin for component (a), those having a novolac structure are preferred from the viewpoints of heat resistance and water resistance, and nitrogen-containing phenolic resins are preferred, and triazine skeleton-containing phenolic resins are more preferred from the viewpoint of adhesion to the conductor layer.

[0039] Specific examples of phenol-based resins and naphthol-based resins include "MEH-7700," "MEH-7810," and "MEH-7851" manufactured by Meiwa Chemical Industry Co., Ltd.; "NHN," "CBN," and "GPH" manufactured by Nippon Kayaku Co., Ltd.; "SN170," "SN180," "SN190," "SN475," "SN485," "SN495," "SN-495V," "SN375," and "SN395" manufactured by Nippon Steel Chemical & Material Co., Ltd.; and "TD-2090," "LA-7052," "LA-7054," "LA-1356," "LA-3018-50P," and "EXB-9500" manufactured by DIC Corporation.

[0040] From the viewpoint of significantly achieving the effects of the present invention, the content of the phenolic resin and naphtholic resin as component (a) is preferably 0.5% by mass or more, more preferably 1% by mass or more, and even more preferably 2% by mass or more, relative to 100% by mass of the non-volatile components in the resin composition, and is preferably 10% by mass or less, more preferably 8% by mass or less, and even more preferably 5% by mass or less.

[0041] From the viewpoint of significantly achieving the effects of the present invention, the content of the phenolic resin and naphtholic resin as component (a) is preferably 1% by mass or more, more preferably 2% by mass or more, and even more preferably 3% by mass or more, and is preferably 10% by mass or less, more preferably 8% by mass or less, and even more preferably 5% by mass or less, when the resin component in the resin composition is taken as 100% by mass.

[0042] Examples of cyanate ester resins as component (a) include bifunctional cyanate resins such as bisphenol A dicyanate, polyphenol cyanate, oligo(3-methylene-1,5-phenylene cyanate), 4,4'-methylenebis(2,6-dimethylphenyl cyanate), 4,4'-ethylidene diphenyl dicyanate, hexafluorobisphenol A dicyanate, 2,2-bis(4-cyanate)phenylpropane, 1,1-bis(4-cyanate phenylmethane), bis(4-cyanate-3,5-dimethylphenyl)methane, 1,3-bis(4-cyanate phenyl-1-(methylethylidene))benzene, bis(4-cyanate phenyl)thioether, and bis(4-cyanate phenyl)ether; polyfunctional cyanate resins derived from phenol novolac, cresol novolac, etc.; and prepolymers in which these cyanate resins are partially converted to triazine. Specific examples of cyanate ester resins include "PT30," "PT30S," and "PT60" (phenol novolac-type multifunctional cyanate ester resins), "ULL-950S" (multifunctional cyanate ester resin), "BA230," and "BA230S75" (prepolymers in which part or all of bisphenol A dicyanate has been triazinated to form a trimer), all manufactured by Lonza Japan Co., Ltd. Cyanate ester resins are preferably used as curing agents when the resin composition does not contain (b) an inorganic filler.

[0043] Specific examples of benzoxazine-based resins as component (a) include "JBZ-OD100" (benzoxazine ring equivalent: 218), "JBZ-OP100D" (benzoxazine ring equivalent: 218), and "ODA-BOZ" (benzoxazine ring equivalent: 218) manufactured by JFE Chemical Corporation; "Pd" (benzoxazine ring equivalent: 217) and "Fa" (benzoxazine ring equivalent: 217) manufactured by Shikoku Chemicals Corporation; and "HFB2006M" (benzoxazine ring equivalent: 432) manufactured by Showa Polymer Co., Ltd.

[0044] Specific examples of carbodiimide resins as component (a) include Carbodilite (registered trademark) V-03 (carbodiimide group equivalent: 216, V-05 (carbodiimide group equivalent: 216), V-07 (carbodiimide group equivalent: 200) manufactured by Nisshinbo Chemical Inc.; and Stavaxol (registered trademark) P (carbodiimide group equivalent: 302) manufactured by Rhein Chemie.

[0045] The amine resin as component (a) may be a resin having one or more amino groups in one molecule, such as aliphatic amines, polyether amines, alicyclic amines, and aromatic amines. Among these, aromatic amines are preferred from the viewpoint of achieving the desired effects of the present invention. The amine resin is preferably a primary amine or secondary amine, and more preferably a primary amine. Specific examples of amine resins include 4,4'-methylenebis(2,6-dimethylaniline), diphenyldiaminosulfone, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylsulfone, 3,3'-diaminodiphenylsulfone, m-phenylenediamine, m-xylylenediamine, diethyltoluenediamine, 4,4'-diaminodiphenyl ether, 3,3'-dimethyl-4,4'-diaminobiphenyl, 2,2'-dimethyl-4,4'-diaminobiphenyl, 3,3'-dihydroxybenzidine, and 2,2-bis(3-amino-4-hydroxybenzoyl)methylpropional. Examples of suitable amine resins include 4,4'-bis(4-aminophenyl)propane, 3,3-dimethyl-5,5-diethyl-4,4-diphenylmethanediamine, 2,2-bis(4-aminophenyl)propane, 2,2-bis(4-(4-aminophenoxy)phenyl)propane, 1,3-bis(3-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, 1,4-bis(4-aminophenoxy)benzene, 4,4'-bis(4-aminophenoxy)biphenyl, bis(4-(4-aminophenoxy)phenyl)sulfone, and bis(4-(3-aminophenoxy)phenyl)sulfone. Commercially available amine resins may be used, such as "KAYABOND C-200S," "KAYABOND C-100," "KAYAHARD AA," "KAYAHARD AB," and "KAYAHARD AS" manufactured by Nippon Kayaku Co., Ltd., and "Epicure W" manufactured by Mitsubishi Chemical Corporation.

[0046] The acid anhydride resin as component (a) may be a resin having one or more acid anhydride groups in one molecule. Specific examples of the acid anhydride resin include phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, methylnadic anhydride, hydrogenated methylnadic anhydride, trialkyltetrahydrophthalic anhydride, dodecenyl succinic anhydride, 5-(2,5-dioxotetrahydro-3-furanyl)-3-methyl-3-cyclohexene-1,2-dicarboxylic anhydride, trimellitic anhydride, pyromellitic anhydride, and benzophenonetetracarboxylic dianhydride. Examples of suitable anhydrides include anhydrides, biphenyltetracarboxylic dianhydride, naphthalenetetracarboxylic dianhydride, oxydiphthalic dianhydride, 3,3'-4,4'-diphenylsulfonetetracarboxylic dianhydride, 1,3,3a,4,5,9b-hexahydro-5-(tetrahydro-2,5-dioxo-3-furanyl)-naphtho[1,2-C]furan-1,3-dione, ethylene glycol bis(anhydrotrimellitate), and polymeric anhydrides such as styrene-maleic acid resins, which are copolymers of styrene and maleic acid.

[0047] When an epoxy resin and a curing agent are included as component (a), the ratio of the amount of epoxy resin to the total amount of curing agent, expressed as the ratio of [total number of epoxy groups in the epoxy resin] to [total number of reactive groups in the curing agent], is preferably in the range of 1:0.01 to 1:5, more preferably 1:0.05 to 1:3, and even more preferably 1:0.1 to 1:2. Here, the "number of epoxy groups in the epoxy resin" refers to the sum of all values ​​obtained by dividing the mass of the non-volatile components of the epoxy resin present in the resin composition by the epoxy equivalent. Furthermore, the "number of active groups in the curing agent" refers to the sum of all values ​​obtained by dividing the mass of the non-volatile components of the curing agent present in the resin composition by the active group equivalent. By maintaining the ratio of the epoxy resin to the curing agent as component (a) within this range, a cured product with excellent flexibility can be obtained.

[0048] From the viewpoint of significantly obtaining the effects of the present invention, the content of the curing agent as component (a) is preferably 1% by mass or more, more preferably 3% by mass or more, and even more preferably 5% by mass or more, relative to 100% by mass of the non-volatile components in the resin composition, and is preferably 20% by mass or less, more preferably 15% by mass or less, and even more preferably 10% by mass or less.

[0049] From the viewpoint of significantly obtaining the effects of the present invention, the content of the curing agent as component (a) is preferably 1% by mass or more, more preferably 5% by mass or more, even more preferably 10% by mass or more, 20% by mass or more, or 30% by mass or more, and is preferably 50% by mass or less, more preferably 40% by mass or less, even more preferably 30% by mass or less, or 15% by mass or less, when the resin component in the resin composition is taken as 100% by mass.

[0050] <(b) Inorganic filler> The resin composition may contain (b) an inorganic filler. The (b) inorganic filler is an inorganic compound. Examples of inorganic filler materials include silica, alumina, aluminosilicate, glass, cordierite, silicon oxide, barium sulfate, barium carbonate, talc, clay, mica powder, zinc oxide, hydrotalcite, boehmite, aluminum hydroxide, magnesium hydroxide, calcium carbonate, magnesium carbonate, magnesium oxide, boron nitride, aluminum nitride, manganese nitride, aluminum borate, strontium carbonate, strontium titanate, calcium titanate, magnesium titanate, bismuth titanate, titanium oxide, zirconium oxide, barium titanate, barium titanate zirconate, barium zirconate, calcium zirconate, zirconium phosphate, and zirconium tungstate phosphate. Among these, calcium carbonate and silica are preferred, and silica is particularly preferred. Examples of silica include amorphous silica, fused silica, crystalline silica, synthetic silica, and hollow silica. Moreover, as the silica, spherical silica is preferred. (b) The inorganic filler may be used alone or in combination of two or more kinds.

[0051] Examples of commercially available products of component (b) include "UFP-30" manufactured by Denka; "SP60-05," "SP507-05," and "SPH516-05" manufactured by Nippon Steel Chemical & Material Co., Ltd.; "YC100C," "YA050C," "YA050C-MJE," and "YA010C" manufactured by Admatechs; "Silfill NSS-3N," "Silfill NSS-4N," and "Silfill NSS-5N" manufactured by Tokuyama Corporation; and "SC2500SQ" manufactured by Admatechs.

[0052] The specific surface area of ​​component (b) is preferably 1 m 2 / g or more, more preferably 2m 2 / g or more, particularly preferably 3m 2 / g or more. There is no particular upper limit, but it is preferably 60m 2 / g or less, 50m 2 / g or less or 40m 2 The specific surface area is determined by adsorbing nitrogen gas onto the surface of a sample using a specific surface area measuring device (Macsorb HM-1210 manufactured by Mountech Co., Ltd.) according to the BET method, and then calculating the specific surface area using the BET multipoint method.

[0053] From the viewpoint of significantly achieving the desired effects of the present invention, the average particle size of component (b) is preferably 0.01 μm or more, more preferably 0.05 μm or more, and particularly preferably 0.1 μm or more, and is preferably 5 μm or less, more preferably 2 μm or less, and even more preferably 1 μm or less.

[0054] The average particle size of component (b) can be measured by a laser diffraction / scattering method based on Mie scattering theory. Specifically, a volumetric particle size distribution of the inorganic filler is created using a laser diffraction / scattering particle size distribution analyzer, and the median diameter is used as the average particle size. A measurement sample can be prepared by weighing 100 mg of inorganic filler and 10 g of methyl ethyl ketone into a vial and dispersing them ultrasonically for 10 minutes. The measurement sample is then measured using a laser diffraction particle size distribution analyzer with blue and red light source wavelengths using a flow cell system to measure the volumetric particle size distribution of component (C). The median diameter can then be calculated from the particle size distribution obtained. Examples of laser diffraction particle size distribution analyzers include the LA-960 manufactured by Horiba, Ltd.

[0055] From the viewpoint of improving moisture resistance and dispersibility, it is preferable that component (b) be treated with a surface treatment agent. Examples of surface treatment agents include vinylsilane coupling agents, (meth)acrylic coupling agents, fluorine-containing silane coupling agents, aminosilane coupling agents, epoxysilane coupling agents, mercaptosilane coupling agents, silane coupling agents, alkoxysilanes, organosilazane compounds, and titanate coupling agents. Among these, from the viewpoint of significantly achieving the effects of the present invention, vinylsilane coupling agents, (meth)acrylic coupling agents, and aminosilane coupling agents are preferred. Furthermore, the surface treatment agents may be used alone or in any combination of two or more.

[0056] Commercially available surface treatment agents include, for example, Shin-Etsu Chemical Co., Ltd.'s "KBM1003" (vinyltriethoxysilane), Shin-Etsu Chemical Co., Ltd.'s "KBM503" (3-methacryloxypropyltriethoxysilane), Shin-Etsu Chemical Co., Ltd.'s "KBM403" (3-glycidoxypropyltrimethoxysilane), Shin-Etsu Chemical Co., Ltd.'s "KBM803" (3-mercaptopropyltrimethoxysilane), Shin-Etsu Chemical Co., Ltd.'s "KBE903" (3-aminopropyltriethoxysilane), and Shin-Etsu Chemical Co., Ltd.'s "KBM1003" (vinyltriethoxysilane). Examples of suitable silane coupling agents include "KBM573" (N-phenyl-3-aminopropyltrimethoxysilane) manufactured by Shin-Etsu Chemical Co., Ltd., "SZ-31" (hexamethyldisilazane) manufactured by Shin-Etsu Chemical Co., Ltd., "KBM103" (phenyltrimethoxysilane), "KBM-4803" (long-chain epoxy-type silane coupling agent) manufactured by Shin-Etsu Chemical Co., Ltd., and "KBM-7103" (3,3,3-trifluoropropyltrimethoxysilane) manufactured by Shin-Etsu Chemical Co., Ltd.

[0057] The degree of surface treatment with the surface treatment agent is preferably within a predetermined range from the viewpoint of improving the dispersibility of the inorganic filler. Specifically, 100 parts by mass of the inorganic filler is preferably surface-treated with 0.2 to 5 parts by mass of the surface treatment agent, more preferably 0.2 to 3 parts by mass, and even more preferably 0.3 to 2 parts by mass.

[0058] The degree of surface treatment with the surface treatment agent can be evaluated by the amount of carbon per unit surface area of ​​the inorganic filler. From the viewpoint of improving the dispersibility of the inorganic filler, the amount of carbon per unit surface area of ​​the inorganic filler is set to 0.02 mg / m 2 More than 0.1 mg / m is preferable. 2 More preferably, 0.2 mg / m or more 2 On the other hand, from the viewpoint of suppressing an increase in the melt viscosity of the resin varnish and the melt viscosity in the form of a sheet, it is more preferable that the amount of the resin varnish is 1 mg / m 2 Preferably less than 0.8 mg / m 2 Less than 0.5 mg / m is more preferable. 2 The following is even more preferred:

[0059] The carbon amount per unit surface area of ​​the inorganic filler can be measured after the surface-treated inorganic filler is washed with a solvent (e.g., methyl ethyl ketone (MEK)). Specifically, a sufficient amount of MEK as a solvent is added to the inorganic filler that has been surface-treated with a surface treatment agent, and ultrasonic cleaning is performed at 25°C for 5 minutes. After removing the supernatant and drying the solid content, the carbon amount per unit surface area of ​​the inorganic filler can be measured using a carbon analyzer. The carbon analyzer that can be used is the "EMIA-320V" manufactured by Horiba, Ltd.

[0060] From the viewpoint of reducing the linear thermal expansion coefficient and suppressing the cross-sectional step of the via hole, the content of the (b) component is preferably 50% by mass or less, more preferably 48% by mass or less, and even more preferably 45% by mass or less, and is preferably 0% by mass or more, more preferably 10% by mass or more, and even more preferably 20% by mass or more, or 30% by mass or more, assuming that the non-volatile components in the resin composition are 100% by mass.

[0061] Furthermore, when the nonvolatile components in the resin composition are taken as 100% by mass, the amount of the resin components is preferably 50% by mass or more, more preferably 52% by mass or more, even more preferably 55% by mass or more, and is preferably 100% by mass or less, more preferably 90% by mass or less, even more preferably 80% by mass or less, and particularly preferably 70% by mass or less.

[0062] <(c) Curing accelerator> The resin composition may contain (c) a curing accelerator. Examples of the curing accelerator include phosphorus-based curing accelerators, amine-based curing accelerators, imidazole-based curing accelerators, guanidine-based curing accelerators, and metal-based curing accelerators. Amine-based curing accelerators and imidazole-based curing accelerators are preferred, and amine-based curing accelerators are more preferred. One type of curing accelerator may be used alone, or two or more types may be used in combination.

[0063] Examples of phosphorus-based curing accelerators include triphenylphosphine, phosphonium borate compounds, tetraphenylphosphonium tetraphenylborate, n-butylphosphonium tetraphenylborate, tetrabutylphosphonium decanoate, (4-methylphenyl)triphenylphosphonium thiocyanate, tetraphenylphosphonium thiocyanate, and butyltriphenylphosphonium thiocyanate, with triphenylphosphine and tetrabutylphosphonium decanoate being preferred.

[0064] Examples of the amine curing accelerator include trialkylamines such as triethylamine and tributylamine, 4-dimethylaminopyridine, benzyldimethylamine, 2,4,6-tris(dimethylaminomethyl)phenol, and 1,8-diazabicyclo(5,4,0)-undecene, with 4-dimethylaminopyridine and 1,8-diazabicyclo(5,4,0)-undecene being preferred.

[0065] Examples of the imidazole curing accelerator include 2-methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 1,2-dimethylimidazole, 2-ethyl-4-methylimidazole, 1,2-dimethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 1-benzyl-2-methylimidazole, 1-benzyl-2-phenylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-undecylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 1-cyanoethyl-2-phenylimidazole, 1-cyanoethyl-2-undecylimidazole, 1-cyanoethyl-2-phenylimidazolium trimellitate, 1-cyanoethyl-2-phenylimidazolium trimellitate, 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine, 2, 4-Diamino-6-[2'-undecylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-ethyl-4'-methylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine isocyanuric acid adduct, 2-phenylimidazole isocyanuric acid adduct, 2-phenyl-4,5-dihydroxymethylimidazole, 2-phenyl-4,5-dihydroxymethylimidazole, Examples of the imidazole compound include imidazole compounds such as 2-phenyl-4-methyl-5-hydroxymethylimidazole, 2,3-dihydro-1H-pyrrolo[1,2-a]benzimidazole, 1-dodecyl-2-methyl-3-benzylimidazolium chloride, 2-methylimidazoline, and 2-phenylimidazoline, as well as adducts of imidazole compounds with epoxy resins, and 2-ethyl-4-methylimidazole and 1-benzyl-2-phenylimidazole are preferred.

[0066] As the imidazole-based curing accelerator, commercially available products may be used, for example, "P200-H50" manufactured by Mitsubishi Chemical Corporation.

[0067] Examples of guanidine-based curing accelerators include dicyandiamide, 1-methylguanidine, 1-ethylguanidine, 1-cyclohexylguanidine, 1-phenylguanidine, 1-(o-tolyl)guanidine, dimethylguanidine, diphenylguanidine, trimethylguanidine, tetramethylguanidine, pentamethylguanidine, 1,5,7-triazabicyclo[4.4.0]dec-5-ene, and 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene. Examples of suitable biguanide include 1-methylbiguanide, 1-ethylbiguanide, 1-n-butylbiguanide, 1-n-octadecylbiguanide, 1,1-dimethylbiguanide, 1,1-diethylbiguanide, 1-cyclohexylbiguanide, 1-allylbiguanide, 1-phenylbiguanide, and 1-(o-tolyl)biguanide. Of these, dicyandiamide and 1,5,7-triazabicyclo[4.4.0]dec-5-ene are preferred.

[0068] Examples of metal-based curing accelerators include organometallic complexes or organometallic salts of metals such as cobalt, copper, zinc, iron, nickel, manganese, and tin. Specific examples of organometallic complexes include organic cobalt complexes such as cobalt(II) acetylacetonate and cobalt(III) acetylacetonate, organic copper complexes such as copper(II) acetylacetonate, organic zinc complexes such as zinc(II) acetylacetonate, organic iron complexes such as iron(III) acetylacetonate, organic nickel complexes such as nickel(II) acetylacetonate, and organic manganese complexes such as manganese(II) acetylacetonate. Examples of organometallic salts include zinc octoate, tin octoate, zinc naphthenate, cobalt naphthenate, tin stearate, and zinc stearate.

[0069] From the viewpoint of significantly achieving the effects of the present invention, the content of (c) the curing accelerator is preferably 0.01% by mass or more, more preferably 0.02% by mass or more, and particularly preferably 0.03% by mass or more, and is preferably 3% by mass or less, more preferably 1% by mass or less, and particularly preferably 0.5% by mass or less, when the non-volatile components in the resin composition are taken as 100% by mass.

[0070] From the viewpoint of significantly achieving the effects of the present invention, the content of (c) the curing accelerator is preferably 0.01% by mass or more, more preferably 0.02% by mass or more, and particularly preferably 0.03% by mass or more, and is preferably 3% by mass or less, more preferably 1% by mass or less, and particularly preferably 0.5% by mass or less, when the resin component in the resin composition is taken as 100% by mass.

[0071] <(d) Thermoplastic resin> The resin composition may contain (d) a thermoplastic resin. Examples of (d) thermoplastic resins include phenoxy resins, polyvinyl acetal resins, polyolefin resins, polyimide resins, polyamideimide resins, polyetherimide resins, polysulfone resins, polyethersulfone resins, polyphenylene ether resins, polyetheretherketone resins, and polyester resins, with phenoxy resins being preferred. The thermoplastic resins may be used alone or in combination of two or more.

[0072] The polystyrene-equivalent weight-average molecular weight of the (d) thermoplastic resin is preferably 38,000 or more, more preferably 40,000 or more, and even more preferably 42,000 or more. The upper limit is preferably 100,000 or less, more preferably 70,000 or less, and even more preferably 60,000 or less. The polystyrene-equivalent weight-average molecular weight of the (d) thermoplastic resin is measured by gel permeation chromatography (GPC). Specifically, the polystyrene-equivalent weight-average molecular weight of the (d) thermoplastic resin is measured using a Shimadzu LC-9A / RID-6A measuring instrument, a Showa Denko Shodex K-800P / K-804L / K-804L column, and chloroform or the like as the mobile phase at a column temperature of 40°C, and can be calculated using a calibration curve of standard polystyrene.

[0073] Examples of phenoxy resins include phenoxy resins having one or more skeletons selected from the group consisting of bisphenol A, bisphenol F, bisphenol S, bisphenolacetophenone, novolac, biphenyl, fluorene, dicyclopentadiene, norbornene, naphthalene, anthracene, adamantane, terpene, and trimethylcyclohexane. The terminal of the phenoxy resin may be any functional group such as a phenolic hydroxyl group or an epoxy group. One type of phenoxy resin may be used alone, or two or more types may be used in combination. Specific examples of phenoxy resins include "1256" and "4250" (both phenoxy resins containing a bisphenol A skeleton), "YX8100" (phenoxy resin containing a bisphenol S skeleton), and "YX6954" (phenoxy resin containing a bisphenol acetophenone skeleton), all manufactured by Mitsubishi Chemical Corporation. Other examples include "FX280" and "FX293" manufactured by Nippon Steel Chemical & Material Co., Ltd., and "YX7800BH30," "YX8000BH30," "YL7500BH30," "YX6954BH30," "YX7553," "YX7553BH30," "YL7769BH30," "YL6794," "YL7213," "YL7290," and "YL7482" manufactured by Mitsubishi Chemical Corporation.

[0074] Examples of polyvinyl acetal resins include polyvinyl formal resins and polyvinyl butyral resins, with polyvinyl butyral resins being preferred. Specific examples of polyvinyl acetal resins include Denka Butyral 4000-2, Denka Butyral 5000-A, Denka Butyral 6000-C, and Denka Butyral 6000-EP, manufactured by Denki Kagaku Kogyo Co., Ltd., and S-LEC BH series, BX series (e.g., BX-5Z), KS series (e.g., KS-1), BL series, and BM series, manufactured by Sekisui Chemical Co., Ltd.

[0075] Specific examples of polyimide resins include "Rikacoat SN20" and "Rikacoat PN20" manufactured by New Japan Chemical Co., Ltd. Specific examples of polyimide resins also include modified polyimides such as linear polyimides obtained by reacting bifunctional hydroxyl group-terminated polybutadiene, a diisocyanate compound, and a tetrabasic acid anhydride (polyimides described in JP-A No. 2006-37083), and polysiloxane skeleton-containing polyimides (polyimides described in JP-A Nos. 2002-12667 and 2000-319386).

[0076] Specific examples of polyamide-imide resins include "Vylomax HR11NN" and "Vylomax HR16NN" manufactured by Toyobo Co., Ltd. Specific examples of polyamide-imide resins also include modified polyamide-imides such as "KS9100" and "KS9300" (polysiloxane skeleton-containing polyamide-imides) manufactured by Hitachi Chemical Co., Ltd.

[0077] A specific example of polyethersulfone resin is "PES5003P" manufactured by Sumitomo Chemical Co., Ltd. A specific example of polyphenylene ether resin is "OPE-2St 1200" oligophenylene ether styrene resin manufactured by Mitsubishi Gas Chemical Co., Ltd. A specific example of polyetheretherketone resin is "Sumiploy K" manufactured by Sumitomo Chemical Co., Ltd. A specific example of polyetherimide resin is "Ultem" manufactured by GE Corporation.

[0078] Specific examples of polysulfone resins include polysulfones "P1700" and "P3500" manufactured by Solvay Advanced Polymers.

[0079] Examples of polyolefin resins include ethylene copolymer resins such as low-density polyethylene, very low-density polyethylene, high-density polyethylene, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, and ethylene-methyl acrylate copolymer; and polyolefin elastomers such as polypropylene and ethylene-propylene block copolymer.

[0080] Examples of polyester resins include polyethylene terephthalate resin, polyethylene naphthalate resin, polybutylene terephthalate resin, polybutylene naphthalate resin, polytrimethylene terephthalate resin, polytrimethylene naphthalate resin, and polycyclohexane dimethyl terephthalate resin.

[0081] Among these, the (d) thermoplastic resin is preferably a phenoxy resin or a polyvinyl acetal resin. Therefore, in a preferred embodiment, the thermoplastic resin comprises at least one selected from the group consisting of phenoxy resins and polyvinyl acetal resins. Among these, the thermoplastic resin is preferably a phenoxy resin, and a phenoxy resin having a weight-average molecular weight of 40,000 or more is particularly preferred.

[0082] To obtain the effects of the present invention more remarkably, the content of the (d) thermoplastic resin is preferably 0.1% by mass or more, more preferably 0.3% by mass or more, and even more preferably 0.5% by mass or more, based on 100% by mass of the nonvolatile components in the resin composition. The upper limit is preferably 5% by mass or less, more preferably 3% by mass or less, and even more preferably 1% by mass or less.

[0083] From the viewpoint of significantly achieving the effects of the present invention, the content of the (d) thermoplastic resin is preferably 1% by mass or more, more preferably 30.5% by mass or more, and even more preferably 1% by mass or more, and is preferably 20% by mass or less, more preferably 15% by mass or less, and even more preferably 10% by mass or less, when the resin component in the resin composition is taken as 100% by mass.

[0084] <(e) Elastomer> The resin composition may contain (e) an elastomer. The elastomer as component (e) is a flexible resin, preferably a resin having rubber elasticity or a resin that exhibits rubber elasticity by polymerizing with another component. Examples of rubber elasticity include resins that exhibit an elastic modulus of 1 GPa or less when subjected to a tensile test in accordance with Japanese Industrial Standards (JIS K7161) at a temperature of 25°C and a humidity of 40% RH.

[0085] In one embodiment, the (e) elastomer is preferably a resin having, in its molecule, one or more structures selected from a polybutadiene structure, a polysiloxane structure, a poly(meth)acrylate structure, a polyalkylene structure, a polyalkyleneoxy structure, a polyisoprene structure, a polyisobutylene structure, a polycarbonate structure, and a polystyrene structure. "(Meth)acrylate" refers to methacrylate and acrylate.

[0086] In another embodiment, the (e) elastomer is preferably one or more selected from resins having a glass transition temperature (Tg) of 25°C or less and resins that are liquid at 25°C or less. The glass transition temperature of resins having a glass transition temperature (Tg) of 25°C or less is preferably 20°C or less, more preferably 15°C or less. The lower limit of the glass transition temperature is not particularly limited, but is usually -15°C or higher. Furthermore, resins that are liquid at 25°C are preferably resins that are liquid at 20°C or less, more preferably resins that are liquid at 15°C or less. The glass transition temperature can be measured by DSC (differential scanning calorimetry).

[0087] The (e) elastomer is usually an amorphous resin component that can be dissolved in an organic solvent. One type of (e) elastomer may be used alone, or two or more types may be used in combination in any ratio.

[0088] (e) An example of an elastomer is a resin containing a polybutadiene structure. The polybutadiene structure may be contained in the main chain or in a side chain. The polybutadiene structure may be partially or entirely hydrogenated. A resin containing a polybutadiene structure is sometimes called a "polybutadiene resin." Specific examples of polybutadiene resins include "Ricon 130MA8," "Ricon 130MA13," "Ricon 130MA20," "Ricon 131MA5," "Ricon 131MA10," "Ricon 131MA17," "Ricon 131MA20," and "Ricon 184MA6" (polybutadienes containing acid anhydride groups) manufactured by Cray Valley Corporation; "GQ-1000" (polybutadiene having hydroxyl and carboxyl groups introduced therein), "G-1000," "G-2000," and "G-3000" (polybutadienes having hydroxyl groups at both ends), "GI-1000," "GI-2000," and "GI-3000" (hydrogenated polybutadiene having hydroxyl groups at both ends) manufactured by Nippon Soda Co., Ltd.; and "FCA-061L" (an epoxy resin with a hydrogenated polybutadiene backbone) manufactured by Nagase ChemteX Corporation. Specific examples of polybutadiene resins include hydroxyl-terminated polybutadiene, linear polyimides made from diisocyanate compounds and tetrabasic acid anhydrides (polyimides described in JP 2006-37083 A and WO 2008 / 153208 A), and phenolic hydroxyl group-containing butadienes. The content of the butadiene structure in the polyimide resin is preferably 60% by mass to 95% by mass, more preferably 75% by mass to 85% by mass. For details of the polyimide resin, please refer to the descriptions in JP 2006-37083 A and WO 2008 / 153208 A, the contents of which are incorporated herein by reference.

[0089] (e) An example of an elastomer is a resin containing a poly(meth)acrylate structure. A resin containing a poly(meth)acrylate structure is sometimes called a "poly(meth)acrylic resin." Specific examples of poly(meth)acrylic resins include Teisan Resin manufactured by Nagase ChemteX Corporation, and ME-2000, W-116.3, W-197C, KG-25, and KG-3000 manufactured by Negami Chemical Industrial Co., Ltd.

[0090] Examples of (e) elastomers include resins containing a polycarbonate structure. Resins containing a polycarbonate structure are sometimes referred to as "polycarbonate resins." Specific examples of polycarbonate resins include "T6002" and "T6001" (polycarbonate diols) manufactured by Asahi Kasei Chemicals Corporation, and "C-1090," "C-2090," and "C-3090" (polycarbonate diols) manufactured by Kuraray Co., Ltd. Linear polyimides made from hydroxyl-terminated polycarbonates, diisocyanate compounds, and tetrabasic acid anhydrides can also be used. The carbonate structure content of the polyimide resin is preferably 60% to 95% by mass, more preferably 75% to 85% by mass. For details of the polyimide resin, please refer to the description in International Publication No. 2016 / 129541, the contents of which are incorporated herein by reference.

[0091] Examples of (e) elastomers include resins containing a polysiloxane structure. Resins containing a polysiloxane structure are sometimes called "siloxane resins." Specific examples of siloxane resins include "SMP-2006," "SMP-2003PGMEA," and "SMP-5005PGMEA" manufactured by Shin-Etsu Silicones Co., Ltd., and linear polyimides made from amine-terminated polysiloxanes and tetrabasic acid anhydrides (see, for example, International Publication No. 2010 / 053185, JP 2002-12667 A, and JP 2000-319386 A).

[0092] Examples of the (e) elastomer include resins containing a polyalkylene structure or a polyalkyleneoxy structure. A resin containing a polyalkylene structure is sometimes called an "alkylene resin." A resin containing a polyalkyleneoxy structure is sometimes called an "alkyleneoxy resin." The polyalkyleneoxy structure is preferably a polyalkyleneoxy structure having 2 to 15 carbon atoms, more preferably a polyalkyleneoxy structure having 3 to 10 carbon atoms, and particularly preferably a polyalkyleneoxy structure having 5 to 6 carbon atoms. Specific examples of alkylene resins and alkyleneoxy resins include "PTXG-1000" and "PTXG-1800" manufactured by Asahi Kasei Fibers Corporation.

[0093] (e) Examples of elastomers include resins containing a polyisoprene structure. Resins containing a polyisoprene structure are sometimes called "isoprene resins." Specific examples of isoprene resins include "KL-610" and "KL613" manufactured by Kuraray Co., Ltd.

[0094] (e) An example of an elastomer is a resin containing a polyisobutylene structure. A resin containing a polyisobutylene structure is sometimes called an "isobutylene resin." Specific examples of isobutylene resins include "SIBSTAR-073T" (styrene-isobutylene-styrene triblock copolymer) and "SIBSTAR-042D" (styrene-isobutylene diblock copolymer), both manufactured by Kaneka Corporation.

[0095] (e) An example of an elastomer is a resin containing a polystyrene structure. A resin containing a polystyrene structure is sometimes called a "styrene resin." Examples of styrene resins include styrene-butadiene-styrene block copolymers (SBS), styrene-isoprene-styrene block copolymers (SIS), styrene-ethylene-butylene-styrene block copolymers (SEBS), styrene-ethylene-propylene-styrene block copolymers (SEPS), styrene-ethylene-ethylene-propylene-styrene block copolymers (SEEPS), styrene-butadiene-butylene-styrene block copolymers (SBBS), styrene-butadiene diblock copolymers, hydrogenated styrene-butadiene block copolymers, hydrogenated styrene-isoprene block copolymers, and hydrogenated styrene-butadiene random copolymers. Specific examples of styrene resins include hydrogenated styrene-based thermoplastic elastomers "H1041," "Tuftec H1043," "Tuftec P2000," and "Tuftec MP10" (manufactured by Asahi Kasei Corporation); epoxidized styrene-butadiene thermoplastic elastomers "Epofriend AT501" and "CT310" (manufactured by Daicel Corporation); modified styrene-based elastomers having hydroxyl groups "Septon HG252" (manufactured by Kuraray Co., Ltd.); modified styrene-based elastomers having carboxyl groups "Tuftec N503M," modified styrene-based elastomers having amino groups "Tuftec N501," modified styrene-based elastomers having acid anhydride groups "Tuftec M1913" (manufactured by Asahi Kasei Chemicals Corporation); unmodified styrene-based elastomers "Septon S8104" (manufactured by Kuraray Co., Ltd.); and styrene-ethylene / butylene-styrene block copolymer "FG1924" (manufactured by Kraton).

[0096] The number average molecular weight (Mn) of the (e) elastomer is preferably 1,000 or more, more preferably 1,500 or more, even more preferably 3,000 or more, and particularly preferably 5,000 or more, and is preferably 1,000,000 or less, more preferably 900,000 or less. The number average molecular weight (Mn) can be measured in terms of polystyrene using GPC (gel permeation chromatography).

[0097] From the viewpoint of significantly achieving the effects of the present invention, the content of the (e) elastomer is preferably 1% by mass or more, more preferably 2% by mass or more, and even more preferably 5% by mass or more, and is preferably 15% by mass or less, more preferably 10% by mass or less, and even more preferably 8% by mass or less, based on 100% by mass of non-volatile components in the resin composition.

[0098] From the viewpoint of significantly obtaining the effects of the present invention, the content of the (e) elastomer is preferably 1% by mass or more, more preferably 3% by mass or more, and even more preferably 5% by mass or more, and is preferably 20% by mass or less, more preferably 15% by mass or less, and even more preferably 10% by mass or less, when the resin component in the resin composition is taken as 100% by mass.

[0099] <(f) Other additives> In addition to the above-mentioned components, the resin composition may further contain other additives as optional components. Examples of such additives include flame retardants, organic fillers, organometallic compounds such as organocopper compounds, organozinc compounds, and organocobalt compounds, thickeners, antifoaming agents, leveling agents, adhesion promoters, and colorants. These additives may be used alone or in combination of two or more in any ratio. The content of each additive can be determined appropriately by those skilled in the art.

[0100] The method for preparing the resin composition is not particularly limited, and examples thereof include a method in which the ingredients are mixed and dispersed, if necessary, together with a solvent, using a rotary mixer or the like.

[0101] A cured product (insulating layer) obtained by curing the resin composition at 190°C for 1.5 hours usually exhibits the property of a low coefficient of linear thermal expansion (CTE). The coefficient of linear thermal expansion is preferably 55 ppm / °C or less, more preferably 50 ppm / °C or less, and even more preferably 40 ppm / °C or less. The coefficient of linear thermal expansion can be measured using a thermomechanical analyzer (TMA, SS6100) manufactured by Seiko Instruments Inc., and in detail can be measured by the method described in the Examples below.

[0102] [Resin sheet] The resin sheet includes a support and a resin composition layer formed from a resin composition provided on the support. The resin composition is as described above.

[0103] The thickness of the resin composition layer is preferably 100 μm or less, more preferably 50 μm or less, and even more preferably 40 μm or less, 30 μm or less, or 20 μm or less, from the viewpoint of making the printed wiring board thinner and being able to provide a cured product of the resin composition that has excellent insulating properties even when the cured product is thin. The lower limit of the thickness of the resin composition layer is not particularly limited, but can usually be 1 μm or more, 5 μm or more, etc.

[0104] Examples of the support include films made of plastic materials, metal foils, and release papers, with films made of plastic materials and metal foils being preferred.

[0105] When a film made of a plastic material is used as the support, examples of the plastic material include polyesters such as polyethylene terephthalate (hereinafter sometimes abbreviated as "PET") and polyethylene naphthalate (hereinafter sometimes abbreviated as "PEN"), polycarbonate (hereinafter sometimes abbreviated as "PC"), acrylics such as polymethyl methacrylate (PMMA), cyclic polyolefins, triacetyl cellulose (TAC), polyether sulfide (PES), polyether ketone, polyimide, etc. Among these, polyethylene terephthalate and polyethylene naphthalate are preferred, with inexpensive polyethylene terephthalate being particularly preferred.

[0106] When a metal foil is used as the support, examples of the metal foil include copper foil and aluminum foil, with copper foil being preferred. The copper foil may be a foil made of a single metal, copper, or an alloy of copper and another metal (e.g., tin, chromium, silver, magnesium, nickel, zirconium, silicon, titanium, etc.).

[0107] The surface of the support that is to be bonded to the resin composition layer may be subjected to a matte treatment, a corona treatment, or an antistatic treatment.

[0108] The support may also be a support with a release layer, which has a release layer on the surface that bonds with the resin composition layer. Examples of the release agent used in the release layer of the support with a release layer include one or more release agents selected from the group consisting of alkyd resins, polyolefin resins, urethane resins, and silicone resins. Commercially available products may also be used as the support with a release layer, including PET films with a release layer primarily composed of an alkyd resin-based release agent, such as "SK-1," "AL-5," and "AL-7" manufactured by Lintec Corporation, "Lumirror T60" manufactured by Toray Industries, Inc., "Purex" manufactured by Teijin Limited, and "Uni-Peel" manufactured by Unitika Limited; and "U2-NR1" manufactured by DuPont Films.

[0109] The thickness of the support is not particularly limited, but is preferably in the range of 5 μm to 75 μm, more preferably 10 μm to 60 μm. When a support with a release layer is used, it is preferable that the thickness of the entire support with a release layer is in the above range.

[0110] In one embodiment, the resin sheet may further include other layers as necessary. Examples of such other layers include a protective film conforming to the support and provided on the surface of the resin composition layer that is not bonded to the support (i.e., the surface opposite the support). The thickness of the protective film is not particularly limited, but is, for example, 1 μm to 40 μm. By laminating the protective film, adhesion of dust and the like to the surface of the resin composition layer and scratches can be suppressed.

[0111] The resin sheet can be produced, for example, by preparing a resin varnish by dissolving a resin composition in an organic solvent, applying this resin varnish to a support using a die coater or the like, and then drying it to form a resin composition layer.

[0112] Examples of organic solvents include ketones such as acetone, methyl ethyl ketone (MEK), and cyclohexanone; acetate esters such as ethyl acetate, butyl acetate, cellosolve acetate, propylene glycol monomethyl ether acetate, and carbitol acetate; carbitols such as cellosolve and butyl carbitol; aromatic hydrocarbons such as toluene and xylene; and amide solvents such as dimethylformamide, dimethylacetamide (DMAc), and N-methylpyrrolidone. The organic solvents may be used alone or in combination of two or more.

[0113] Drying may be carried out by known methods such as heating or hot air blowing. Drying conditions are not particularly limited, but drying is carried out so that the content of organic solvent in the resin composition layer becomes 10% by mass or less, preferably 5% by mass or less. Although this varies depending on the boiling point of the organic solvent in the resin varnish, for example, when a resin varnish containing 30% by mass to 60% by mass of organic solvent is used, the resin composition layer can be formed by drying at 50°C to 150°C for 3 to 10 minutes.

[0114] The resin sheet can be stored in a rolled state. When the resin sheet has a protective film, it can be used by peeling off the protective film.

[0115] [Printed wiring boards and methods for manufacturing printed wiring boards] As shown in FIG. 1 , a printed wiring board 1 according to one embodiment of the present invention includes, in this order, an inner circuit board 2, an insulating layer 3 containing a cured product of the resin composition described above, and a resin layer 4. The resin layer 4 has a first surface 4a facing the insulating layer 3 and a second surface 4b opposite the first surface 4a. Because the insulating layer 3 is in contact with the first surface 4a of the resin layer 4, there is typically no other layer between the resin layer 4 and the insulating layer 3. As shown in FIG. 1 , a conductor layer 5 may typically be provided on the second surface 4b of the resin layer 4. The insulating layer 3 and the resin layer 4 each have a via hole 6 formed therein, penetrating the insulating layer 3 and the resin layer 4 in the thickness direction. The via hole 6 is typically used for electrical connection between the conductor layer 5 and a metal layer (not shown) such as wiring provided on the inner circuit board 2. For example, a conductor layer 5 (not shown) is formed not only on the second surface 4b of the resin layer 4 but also in the via holes 6, so that electrical continuity between the conductor layer 5 and the metal layer of the inner circuit board 2 is achieved.

[0116] A step may be formed in the via hole 6 at the position of the first surface 4a of the resin layer 4. Such a step may be formed, for example, by the following mechanism. Typically, after the via hole 6 is formed, a desmear treatment is performed to remove smears in the via hole 6. In the desmear treatment, an oxidizer solution is generally brought into contact with the insulating layer 3 and the resin layer 4. In this desmear treatment, contact with the oxidizer solution causes the resin components contained in the insulating layer 3 and the resin layer 4 to fall off and dissolve, thereby roughening the surfaces of each layer. At this time, the degree to which the surface roughening of each layer progresses may differ depending on the components contained in each layer. Therefore, a step may be formed at the position of the first surface 4a of the resin layer 4.

[0117] When such a step is formed, a distance d may be formed between an end 41 of the first surface 4a in the via hole 6 and an end 42 of the contact surface between the first surface 4a and the insulating layer 3. Here, unless otherwise specified, "end 41 of the first surface 4a in the via hole 6" refers to the end of the first surface 4a that is closer to the center of the via hole 6. Also, unless otherwise specified, "end 42 of the contact surface between the first surface 4a and the insulating layer 3" refers to the end of the contact surface between the first surface 4a and the insulating layer 3 that is closer to the center of the via hole 6. Also, hereinafter, the distance d may be referred to as "step distance" d.

[0118] When the via hole 6 is formed by irradiating a laser, heat generated by the laser irradiation can cause interfacial peeling between the resin layer 4 and the insulating layer 3. Furthermore, the heat from the laser irradiation can deteriorate the resin around the via hole 6 in the insulating layer 3. If such interfacial peeling and resin deterioration occur, the insulating layer 3 is significantly eroded during the desmearing process, which can result in an increase in the step distance d. If the step distance d is increased in this way, there will be areas where the conductor layer 5 is not formed when it is formed in the via hole 6, which can result in a decrease in the reliability of the electrical connection.

[0119] In the printed wiring board 1 of the present invention, the step distance d can be reduced by adjusting the components in the resin composition, and more preferably by forming the via holes 6 by plasma treatment. Specifically, the top diameter a (μm) of the via holes 6 and the step distance d (μm) within the via holes 6 are [d / {(1 / 2)×a}]×100≦5 It is possible to satisfy the relationship shown below. Here, unless otherwise specified, the top diameter a of the via hole 6 refers to the diameter of the opening of the via hole 6 on the side opposite to the inner layer circuit board 2. This prevents the occurrence of areas where the conductor layer 5 is not formed when forming the conductor layer 5 inside the via hole 6, thereby improving the reliability of the electrical connection.

[0120] The value of [d / {(1 / 2)×a}]×100 is usually 5 or less, preferably 4.5 or less, and more preferably 4 or less. It may also be preferably 0 or more, and more preferably 0.5 or more. [d / {(1 / 2)×a}]×100 can be measured according to the description in the Examples below.

[0121] The printed wiring board of the present invention can generally reduce unevenness at the bottom and sidewall of the via hole where the inorganic filler is excavated. As a result, it is possible to make the thickness of the conductor layer formed in the via hole uniform, thereby improving the reliability of the electrical connection. When the resin composition of the present invention contains an inorganic filler, the inorganic filler has a small average particle size, and the content thereof is 50% by mass or less when the non-volatile components of the resin composition are 100% by mass, thereby reducing unevenness.

[0122] From the viewpoint of thinning the printed wiring board, the thickness of the insulating layer is preferably 100 μm or less, more preferably 50 μm or less, even more preferably 40 μm or less, 30 μm or less, or 20 μm or less, and is preferably 1 μm or more, more preferably 5 μm or more.

[0123] From the viewpoint of thinning the printed wiring board, the thickness of the resin layer is preferably 100 μm or less, more preferably 50 μm or less, even more preferably 40 μm or less, 30 μm or less, or 20 μm or less, and is preferably 1 μm or more, more preferably 5 μm or more.

[0124] From the viewpoint of thinning the printed wiring board, the total thickness of the insulating layer and the resin layer is preferably 200 μm or less, more preferably 100 μm or less, even more preferably 80 μm or less, 60 μm or less, or 40 μm or less, and is preferably 2 μm or more, more preferably 6 μm or more, and even more preferably 10 μm or more.

[0125] When the thickness of the resin layer is b and the thickness of the insulating layer is c, from the viewpoint of thinning the printed wiring board, b / c is preferably 0.5 or more, more preferably 1 or more, even more preferably 1.5 or more, and is preferably 10 or less, more preferably 5 or less, even more preferably 3 or less.

[0126] The method for producing a printed wiring board of the present invention comprises: (A) forming a resin layer on the surface of the resin composition layer of the resin sheet that is not bonded to the support; (B) a step of laminating a resin sheet having a resin layer formed thereon on an inner layer circuit board and curing the resin composition layer to form an insulating layer; (C) a step of performing plasma treatment on the surface of the resin layer to form via holes; (D) a roughening treatment step, and (E) forming a conductive layer on the surface of the resin layer.

[0127] The insulating layer used in the printed wiring board of the present invention functions as an insulating layer that insulates each layer, and also functions as a bonding sheet that bonds the inner layer circuit board and the resin layer.

[0128] The method for producing a printed wiring board is preferably carried out in the order of step (A), step (B), step (C), step (D) and step (E). Each step of the method for producing a printed wiring board will be described below.

[0129] <Process (A)> In step (A), a resin layer is formed on the surface of the resin composition layer of the resin sheet that is not bonded to the support (i.e., the surface opposite to the support). Specifically, a film-like resin layer is laminated on the surface of the resin composition layer that is not bonded to the support, thereby forming a resin layer on the resin composition layer. The lamination of the resin composition layer and the resin layer may be performed under the same conditions as those for laminating the inner layer circuit board and the resin composition layer, which will be described later. Alternatively, a resin varnish may be prepared by dissolving the material for the resin layer in an organic solvent, and this resin varnish may be applied to the resin composition layer using a die coater or the like, and then dried to form a resin layer. The organic solvent is as described above.

[0130] The resin layer may be formed of a thermoplastic resin. Examples of materials for the resin layer include polyimide, liquid crystal polymer, polyethylene terephthalate, polyethylene naphthalate, polyphenylene sulfide, polyether ether ketone, polybenzimidazole, aramid, polyamideimide, and polyetherimide. Among these, the material for the resin layer is preferably either a polyimide resin or a liquid crystal polymer.

[0131] The surface of the resin layer may be subjected to corona treatment, plasma treatment, or UV treatment. Use of such a resin layer can enhance the adhesion between the resin layer and the insulating layer. The conditions for the corona treatment, plasma treatment, or UV treatment may be determined appropriately depending on the material of the resin layer, etc.

[0132] In step (A), a laminate having a resin layer and a metal foil such as copper foil may be laminated on the resin composition layer so that the resin layer faces the side of the resin composition layer that is not bonded to the support, thereby forming a resin layer on the resin composition layer. In this case, the metal foil is removed by etching after step (A) is completed and before step (B) is started, or after step (B) is completed.

[0133] The resin layer may be a commercially available product, for example, "Vecstar-FCCL:CTF-25" manufactured by Kuraray Co., Ltd., or a polyimide copper-clad laminate (ESPANEX: MC12-25-00HRM, manufactured by Nippon Steel Chemical Co., Ltd.).

[0134] The printed wiring board of the present invention typically exhibits excellent lamination between the resin composition layer and the resin layer. This makes it possible to uniformly form the thickness of the conductor layer formed in the via hole, thereby improving the reliability of the electrical connection. Specifically, the lamination property is determined by forming a resin layer on the surface of the resin sheet where the resin composition layer is not bonded to the support. When the resin sheet on which the resin layer is formed is cut to an appropriate size, no lift is usually observed around the cut edge due to insufficient adhesion between the resin layer and the resin composition layer. The lamination property can be measured by the method described in the examples below.

[0135] <Process (B)> In step (B), a resin sheet having a resin layer formed thereon is laminated on an inner layer circuit board, and the resin composition layer is cured to form an insulating layer. In step (B), an insulating layer is usually formed on a main surface of the inner layer circuit board. The main surface of the inner layer circuit board refers to the surface of the inner layer circuit board on which the insulating layer is provided.

[0136] Step (B) may include a step (B-1) of preparing an inner circuit board. The inner circuit board typically comprises a support substrate and a metal layer provided on the surface of the support substrate. The metal layer is exposed on the main surface of the inner circuit board.

[0137] Examples of materials for the support substrate include a glass epoxy substrate, a metal substrate, a polyester substrate, a polyimide substrate, a BT resin substrate, a thermosetting polyphenylene ether substrate, etc. Examples of materials for the metal layer include copper foil, copper foil with a carrier, and materials for the conductor layer described below, with copper foil being preferred.

[0138] In step (B), for example, a resin composition layer of a resin sheet on which a resin layer has been formed is laminated on the main surface of an inner layer circuit board, and the resin composition layer is thermally cured to form an insulating layer.

[0139] The lamination of the inner layer circuit board and the resin sheet can be carried out, for example, by peeling off the support and then thermocompressing the resin sheet to the inner layer circuit board from the resin layer side. Typically, the lamination is carried out so that the inner layer circuit board and the resin composition layer are bonded together. Examples of the member for thermocompression bonding the resin sheet to the inner layer circuit board (hereinafter also referred to as the "thermocompression bonding member") include a heated metal plate (such as a SUS panel) or a metal roll (SUS roll). It is preferable to press the thermocompression bonding member not directly onto the resin sheet but via an elastic material such as heat-resistant rubber so that the resin sheet can adequately conform to the surface irregularities of the inner layer circuit board.

[0140] The lamination of the inner layer circuit board and the resin sheet may be carried out by a vacuum lamination method. In the vacuum lamination method, the thermocompression temperature is preferably in the range of 60°C to 160°C, more preferably 80°C to 140°C, the thermocompression pressure is preferably in the range of 0.098MPa to 1.77MPa, more preferably 0.29MPa to 1.47MPa, and the thermocompression time is preferably in the range of 20 seconds to 400 seconds, more preferably 30 seconds to 300 seconds. The lamination is preferably carried out under reduced pressure conditions of 26.7hPa or less.

[0141] The lamination can be performed using a commercially available vacuum laminator, such as a vacuum pressure laminator manufactured by Meiki Seisakusho Co., Ltd., a vacuum applicator manufactured by Nikko Materials Co., Ltd., or a batch vacuum pressure laminator.

[0142] After lamination, the laminated resin sheets may be smoothed under normal pressure (atmospheric pressure), for example, by pressing a thermocompression member from the resin layer side. The pressing conditions for the smoothing treatment may be the same as the thermocompression conditions for lamination. The smoothing treatment may be performed using a commercially available laminator. Note that lamination and smoothing treatment may be performed consecutively using the commercially available vacuum laminator.

[0143] After laminating the resin sheet on the inner layer circuit board, the resin composition layer is heat-cured to form an insulating layer. The heat-curing conditions for the resin composition layer are not particularly limited, and conditions typically employed for forming insulating layers for printed wiring boards may be used.

[0144] For example, although the thermal curing conditions for the resin composition layer vary depending on the type of resin composition, the curing temperature is preferably 120° C. to 240° C., more preferably 150° C. to 220° C., and even more preferably 170° C. to 210° C. The curing time is preferably 5 minutes to 120 minutes, more preferably 10 minutes to 100 minutes, and even more preferably 15 minutes to 100 minutes.

[0145] Before thermally curing the resin composition layer, the resin composition layer may be preheated at a temperature lower than the curing temperature. For example, prior to thermally curing the resin composition layer, the resin composition layer may be preheated at a temperature of 50°C or higher but lower than 120°C (preferably 60°C or higher but 115°C or lower, more preferably 70°C or higher but 110°C or lower) for 5 minutes or longer (preferably 5 to 150 minutes, more preferably 15 to 120 minutes, and even more preferably 15 to 100 minutes).

[0146] Instead of forming an insulating layer using a resin sheet, a resin composition may be applied directly to the main surface of the inner layer circuit board, followed by forming a resin layer and thermally curing the resin composition to form the insulating layer. The conditions for forming the insulating layer in this case are the same as those for forming an insulating layer using a resin sheet. The resin composition to be applied is as described above. The resin layer is formed by laminating it on the resin composition, and the resin layer and lamination conditions are as described above.

[0147] After step (B) is completed and before step (C) is performed, a step of forming a mask for plasma treatment on the insulating layer may be performed to effectively form via holes in the insulating layer. The step of forming the mask may include, for example, (B-2) a step of laminating a dry film on the resin layer, and (B-3) a step of exposing and developing the dry film using a photomask to obtain a patterned dry film.

[0148] In step (B-2), a dry film is laminated onto the resin layer formed on the main surface of the inner layer circuit board. The lamination conditions for the resin layer and the dry film may be the same as the lamination conditions for the inner layer circuit board and the resin sheet.

[0149] The dry film used in step (B-2) may be any film that can be patterned by exposure and development, and preferably has resistance to the plasma treatment in step (C). A photosensitive dry film made of a photoresist composition may be used as the dry film. Examples of such dry films include dry films made of resins such as novolac resins and acrylic resins.

[0150] From the viewpoint of improving the processability of via holes, the thickness of the dry film is preferably 10 μm or more, more preferably 15 μm or more, and even more preferably 20 μm or more, and is preferably 100 μm or less, more preferably 70 μm or less, and even more preferably 50 μm or less.

[0151] In step (B-3), exposure is performed by irradiating the dry film with active energy rays through a photomask having a predetermined pattern. The details of exposure are usually to irradiate the surface of the dry film with active energy rays through a photomask to photocure the exposed portion of the dry film. Examples of active energy rays include ultraviolet rays, visible light, electron beams, and X-rays, with ultraviolet rays being preferred. The dose and duration of ultraviolet light irradiation can be appropriately set depending on the dry film. Examples of exposure methods include contact exposure, in which a mask pattern is brought into close contact with the dry film and exposed, and non-contact exposure, in which a mask pattern is not brought into close contact with the dry film and exposed using parallel light.

[0152] After exposure, development is performed to remove either the exposed or unexposed portions of the dry film (usually the unexposed portions) to form a patterned dry film as a mask. Development may be performed by either wet development or dry development. Examples of development methods include dipping, puddling, spraying, brushing, and scraping.

[0153] In the step (C) described below, plasma treatment is carried out using the patterned dry film as a mask to form via holes.

[0154] <Process (C)> Step (C) is a step of performing a plasma treatment on the surface of the resin layer to form via holes in the resin layer and the insulating layer. Because the insulating layer contains a cured product of the resin composition of the present invention, even when via holes are formed by plasma treatment, the step distance d from the edge of the first surface in the via hole to the edge of the laminated surface between the first surface and the insulating layer can be reduced, resulting in improved reliability of electrical connection. Furthermore, unlike sandblasting, plasma treatment can smoothly form via holes even when the resin layer is formed of a flexible material such as a thermoplastic resin.

[0155] In the plasma treatment, the surface of the resin layer is treated with plasma generated by introducing a gas into a plasma generator, thereby forming via holes in the resin layer and the insulating layer. The method for generating plasma is not particularly limited, and examples thereof include microwave plasma in which plasma is generated by microwaves, high-frequency plasma using high frequency waves, atmospheric pressure plasma generated under atmospheric pressure, and atmospheric pressure plasma generated in a vacuum, among which atmospheric pressure plasma generated in a vacuum is preferred.

[0156] The plasma used in step (C) is preferably RF plasma excited by high frequency waves.

[0157] The gas to be converted into plasma can be a gas that etches only the cured resin component in the insulating layer and removes the inorganic filler. Such gases are preferably CF4, Ar, O2, N2, or a gas consisting of a combination thereof, more preferably a mixed gas containing O2 and CF4, Ar, and N2, and even more preferably a mixed gas of CF4 and O2.

[0158] The irradiation time in the plasma treatment is preferably 1 minute or more, more preferably 2 minutes or more, and even more preferably 3 minutes or more, since the insulating layer contains a resin composition that is excellent in plasma processability. The upper limit is not particularly limited, but is preferably 60 minutes or less, more preferably 30 minutes or less, and more preferably 20 minutes or less.

[0159] In the present invention, the via holes are formed by plasma treatment, so the top diameter a of the via holes can be made small. The top diameter a is preferably 50 μm or less, more preferably 40 μm or less, and even more preferably 30 μm or less, or 20 μm or less. The lower limit is not particularly limited, but can be 1 μm or more.

[0160] <Process (D)> Step (D) is a step of roughening the surfaces of the resin layer and the insulating layer. Specifically, it is a step of removing foreign matter, such as resin components and inorganic fillers contained in the insulating layer and resin layer that have fallen off in step (C), from the via holes using a treatment liquid. Foreign matter may be present on the surfaces of the resin layer and the insulating layer after step (C). This foreign matter may include, for example, inorganic fillers excavated by plasma treatment or resin components of the resin layer. This foreign matter may cause a decrease in the adhesive strength of the conductor layer. Therefore, step (D) is performed to remove these foreign matter. Specifically, step (D) is a step of contacting the resin layer surface with a treatment liquid after step (C) is completed to remove the foreign matter. Step (D) may be performed once or multiple times.

[0161] The procedure and conditions for step (D) are not particularly limited, and known procedures and conditions commonly used in forming insulating layers for printed wiring boards can be employed. For example, the insulating layer can be roughened by performing a swelling treatment with a swelling liquid, a roughening treatment with an oxidizing agent, and a neutralization treatment with a neutralizing liquid, in that order. The swelling liquid used for the roughening treatment is not particularly limited, but examples include alkaline solutions and surfactant solutions. Alkaline solutions are preferred, and sodium hydroxide solutions and potassium hydroxide solutions are more preferred. Commercially available swelling liquids include "Swelling Dip Securigans P," "Swelling Dip Securigans SBU," and "Swelling Dip Securigant P" manufactured by Atotech Japan. The swelling treatment with a swelling liquid is not particularly limited, but can be performed, for example, by immersing the insulating layer in a swelling liquid at 30°C to 90°C for 1 to 20 minutes. To minimize swelling of the resin in the insulating layer, the insulating layer is preferably immersed in a swelling solution at 40°C to 80°C for 5 to 15 minutes. The oxidizing agent used in the roughening treatment is not particularly limited, but examples include alkaline permanganate solutions prepared by dissolving potassium permanganate or sodium permanganate in an aqueous solution of sodium hydroxide. Roughening treatment using an oxidizing agent such as an alkaline permanganate solution is preferably performed by immersing the insulating layer in an oxidizing agent solution heated to 60°C to 100°C for 10 to 30 minutes. The concentration of permanganate in the alkaline permanganate solution is preferably 5% by mass to 10% by mass. Commercially available oxidizing agents include alkaline permanganate solutions such as "Concentrate Compact CP" and "Dosing Solution Securigance P" manufactured by Atotech Japan. The neutralizing solution used in the roughening treatment is preferably an acidic aqueous solution, and a commercially available product such as "Reduction Solution Securigant P" manufactured by Atotech Japan can be cited. Treatment with a neutralizing solution can be carried out by immersing the surface that has been roughened with an oxidizing agent in a neutralizing solution at 30°C to 80°C for 1 to 30 minutes. From the standpoint of workability, a preferred method is to immerse the object that has been roughened with an oxidizing agent in a neutralizing solution at 40°C to 70°C for 5 to 20 minutes.

[0162] <Process (E)> Step (E) is a step of forming a conductor layer on the surface of the resin layer. In this step, a conductor layer is also typically formed in the via holes. Therefore, a conductor layer may also be formed on the surface of the insulating layer exposed in the via holes. The conductor material used for the conductor layer is not particularly limited. In a preferred embodiment, the conductor layer contains one or more metals selected from the group consisting of gold, platinum, palladium, silver, copper, aluminum, cobalt, chromium, zinc, nickel, titanium, tungsten, iron, tin, and indium. The conductor layer may be a single metal layer or an alloy layer. Examples of alloy layers include layers formed from alloys of two or more metals selected from the above group (e.g., nickel-chromium alloys, copper-nickel alloys, and copper-titanium alloys). Among these, from the viewpoints of versatility in forming the conductor layer, cost, ease of patterning, etc., a single metal layer of chromium, nickel, titanium, aluminum, zinc, gold, palladium, silver, or copper, or an alloy layer of a nickel-chromium alloy, a copper-nickel alloy, or a copper-titanium alloy is preferred, a single metal layer of chromium, nickel, titanium, aluminum, zinc, gold, palladium, silver, or copper, or an alloy layer of a nickel-chromium alloy is more preferred, and a single metal layer of copper is even more preferred.

[0163] The conductor layer may be a single layer structure or a multi-layer structure in which two or more single metal layers or alloy layers made of different types of metals or alloys are laminated. When the conductor layer has a multi-layer structure, the layer in contact with the cured body is preferably a single metal layer of chromium, zinc, or titanium, or an alloy layer of a nickel-chromium alloy.

[0164] The thickness of the conductor layer depends on the desired design of the printed wiring board, but is generally 3 μm to 35 μm, preferably 5 μm to 30 μm.

[0165] In a preferred embodiment of step (E), the conductor layer is formed by sputtering. When forming a conductor layer by sputtering, typically, a conductor seed layer is first formed on the surface of the resin layer by sputtering, and then a conductor sputtered layer is formed on the conductor seed layer by sputtering. Before forming the conductor seed layer by sputtering, the surface of the resin layer may be cleaned by reverse sputtering. Various gases can be used for the reverse sputtering, with Ar, O2, and N2 being preferred. When the seed layer is made of Cu or a Cu alloy, Ar or O2 or an Ar / O2 mixed gas is preferred. When the seed layer is made of Ti, Ar or N2 or an Ar / N2 mixed gas is preferred. When the seed layer is made of Cr or a Cr alloy (such as nichrome), Ar or O2 or an Ar / O2 mixed gas is preferred. Sputtering can be performed using various sputtering devices, such as magnetron sputtering and mirror tron ​​sputtering. Metals that form the conductor seed layer include Cr, Ni, Ti, and nichrome. Cr and Ti are particularly preferred. The thickness of the conductive seed layer is usually preferably 5 nm or more, more preferably 10 nm or more, and is preferably 1000 nm or less, more preferably 500 nm or less. Examples of metals that form the conductive sputtered layer include Cu, Pt, Au, and Pd. Cu is particularly preferred. The thickness of the conductive sputtered layer is usually preferably 50 nm or more, more preferably 100 nm or more, and is preferably 3000 nm or less, more preferably 1000 nm or less.

[0166] After forming a conductor layer by sputtering, a copper plating layer may be further formed on the conductor layer by electrolytic copper plating. The thickness of the copper plating layer is usually preferably 5 μm or more, more preferably 8 μm or more, and is preferably formed to be 75 μm or less, more preferably 35 μm or less. Known methods such as subtractive and semi-additive methods can be used to form the circuit.

[0167] [Semiconductor Devices] The semiconductor device of the present invention includes a printed wiring board, and can be manufactured using a printed wiring board obtained by the manufacturing method of the present invention.

[0168] Examples of semiconductor devices include various semiconductor devices used in electrical appliances (for example, computers, mobile phones, digital cameras, and televisions) and vehicles (for example, motorcycles, automobiles, trains, ships, and aircraft).

[0169] The semiconductor device of the present invention can be manufactured by mounting a component (semiconductor chip) on a conductive portion of a printed wiring board. The "conductive portion" refers to a portion of the printed wiring board that transmits an electrical signal, and the portion may be either on the surface or embedded. The semiconductor chip is not particularly limited as long as it is an electrical circuit element made of a semiconductor material.

[0170] The method of mounting a semiconductor chip when manufacturing a semiconductor device is not particularly limited as long as the semiconductor chip functions effectively, but specific examples include wire bonding mounting, flip chip mounting, bumpless buildup layer (BBUL) mounting, anisotropic conductive film (ACF) mounting, non-conductive film (NCF) mounting, etc. Here, the "bumpless buildup layer (BBUL) mounting method" refers to "a mounting method in which a semiconductor chip is directly embedded in a recess in a printed wiring board and the semiconductor chip is connected to the wiring on the printed wiring board." [Example]

[0171] The present invention will be specifically described below with reference to examples. However, the present invention is not limited to the following examples. In the following description, "parts" and "%" representing amounts mean "parts by mass" and "% by mass", respectively, unless otherwise specified. Furthermore, the operations described below were carried out in an environment of normal temperature and pressure, unless otherwise specified.

[0172] <Inorganic filler used> Inorganic filler 1: Spherical silica (Denka "UFP-30", average particle size 0.078 μm, specific surface area 30.7 m 2The surface was treated with 2 parts of N-phenyl-3-aminopropyltrimethoxysilane (KBM573, manufactured by Shin-Etsu Chemical Co., Ltd.) per 100 parts of the silica gel (100 parts per 100g). Inorganic filler 2: Spherical silica (Admatechs "SC2500SQ", average particle size 0.63 μm, specific surface area 11.2 m) 2 The surface was treated with 1 part of N-phenyl-3-aminopropyltrimethoxysilane (KBM573, manufactured by Shin-Etsu Chemical Co., Ltd.) per 100 parts of the silica gel (100 parts per 100g).

[0173] <Preparation of Resin Composition 1> 6 parts bixylenol type epoxy resin (Mitsubishi Chemical Corporation "YX4000HK", epoxy equivalent weight: approx. 185), 5 parts naphthalene type epoxy resin (Nippon Steel & Sumikin Chemical Co., Ltd. "ESN475V", epoxy equivalent weight: approx. 332), 15 parts bisphenol AF type epoxy resin (Mitsubishi Chemical Corporation "YL7760", epoxy equivalent weight: approx. 238), 2 parts naphthylene ether type epoxy resin (DIC Corporation "HP6000L", epoxy equivalent weight: approx. 213), cyclohexane type epoxy resin (Mitsubishi Chemical Corporation "ZX1 Two parts of phenoxy resin ("YL7500BH30" manufactured by Mitsubishi Chemical Corporation, a 1:1 solution of cyclohexanone and methyl ethyl ketone (MEK) with a solids content of 30% by mass, Mw=44,000), and five parts of hydrogenated styrene-based thermoplastic elastomer ("P2000" manufactured by Asahi Kasei Corporation, styrene / ethylene-butylene-butadiene ratio=67 / 33) were dissolved in a mixed solvent of 20 parts solvent naphtha, 10 parts cyclohexanone, and 10 parts toluene under heating with stirring. After cooling to room temperature, 4 parts of a triazine skeleton-containing cresol novolac curing agent (DIC Corporation's "LA-3018-50P," hydroxyl group equivalent weight approximately 151, 50% solids solution in 2-methoxypropanol), 6 parts of an active ester curing agent (DIC Corporation's "HP-B-8151-62T," active group equivalent weight 238, 62% solids solution in toluene), 30 parts of inorganic filler 1, and 0.05 parts of an amine curing accelerator (4-dimethylaminopyridine (DMAP)) were mixed and dispersed uniformly using a high-speed rotating mixer. The mixture was then filtered through a cartridge filter (ROKITECHNO Corporation's "SHP020") to prepare Resin Composition 1.

[0174] <Preparation of Resin Composition 2> In the preparation of resin composition 1, the amount of inorganic filler 1 was changed from 30 parts to 60 parts. Resin composition 2 was prepared in the same manner as in the preparation of resin composition 1 except for the above.

[0175] <Preparation of Resin Composition 3> In the preparation of resin composition 1, 30 parts of inorganic filler 1 was changed to 60 parts of inorganic filler 2. Resin composition 3 was prepared in the same manner as in the preparation of resin composition 1 except for the above-mentioned changes.

[0176] The following table shows the components and their blending amounts used in preparing Resin Compositions 1 to 3. The abbreviations in the table are as follows: YX4000HK: Bixylenol-type epoxy resin, manufactured by Mitsubishi Chemical Corporation, epoxy equivalent weight approximately 185g / eq. ESN475V: Naphthalene-type epoxy resin, manufactured by Nippon Steel & Sumikin Chemical Co., Ltd., epoxy equivalent weight approximately 332g / eq. YL7760: Bisphenol AF epoxy resin, manufactured by Mitsubishi Chemical Corporation, epoxy equivalent weight approximately 238g / eq. HP6000L: Naphthylene ether epoxy resin, manufactured by DIC Corporation, epoxy equivalent weight approximately 213g / eq. ZX1658GS: Cyclohexane-type epoxy resin, manufactured by Mitsubishi Chemical Corporation, epoxy equivalent weight approximately 135g / eq. BS230S: Cyanate-based curing agent, manufactured by Lonza Japan, cyanate equivalent 232g / eq. LA-3018-50P: Triazine skeleton-containing cresol novolac curing agent, manufactured by DIC Corporation, hydroxyl equivalent weight approximately 151g / eq., 50% solids solution in 2-methoxypropanol HPB-8151-62T: DIC Corporation, active group equivalent weight 238g / eq., toluene solution with 62% solids YX7500BH30: Phenoxy resin, manufactured by Mitsubishi Chemical Corporation, 1:1 solution of cyclohexanone and methyl ethyl ketone (MEK) with a solid content of 30% by mass, Mw=44,000 P2000: Asahi Kasei Corporation, hydrogenated styrene-based thermoplastic elastomer (styrene / ethylene-butylene-butadiene ratio = 67 / 33) DMAP: Amine curing accelerator, 4-dimethylaminopyridine Hardener content: The hardener content when the resin component in the resin composition is 100% by mass. Active ester curing agent content: The active ester curing agent content when the resin component in the resin composition is 100% by mass. Inorganic filler content: The inorganic filler content when the non-volatile components in the resin composition are taken as 100% by mass.

[0177] [Table 1]

[0178] <Preparation of resin sheet> A PET film ("Lumirror R80" manufactured by Toray Industries, Inc., thickness 38 μm, softening point 130°C, "release PET") that had been release-treated with an alkyd resin-based release agent ("AL-5" manufactured by Lintec Corporation) was prepared as a support. Resin compositions 1 to 4 were each uniformly applied to the release agent on the support using a die coater so that the thickness of the resin composition layer after drying would be 15 μm. The film was then dried at 70°C to 95°C for 2 minutes to obtain a resin composition layer on the release PET. Next, a roughened surface of a polypropylene film ("Alphan MA-411" manufactured by Oji F-Tex Co., Ltd., thickness 15 μm) was laminated as a protective film on the side of the resin sheet not bonded to the support so as to bond to the resin composition layer. This resulted in a resin sheet consisting, in this order, of the release PET (support), the resin composition layer, and the protective film.

[0179] <Measurement of thickness of resin composition layer, etc.> The thickness was measured using a contact type film thickness meter (MCD-25MJ, manufactured by Mitutoyo Corporation).

[0180] <Preparation of evaluation board> (1) Preparation of silicon wafer A silicon wafer (copper thickness 1 μm, substrate thickness 0.8 mm, 8-inch size) with a copper layer laminated on one side was prepared as a substrate, and placed in an oven at 130° C. and dried for 30 minutes.

[0181] (2) Laminating the resin layer The protective film was peeled off from each resin sheet, and a liquid crystal polymer film (Vecstar-FCCL:CTF-25, manufactured by Kuraray Co., Ltd., 25 μm thick) was laminated onto the resin composition layer using a batch-type vacuum pressure laminator (Nikko Materials Co., Ltd., single-stage build-up laminator, V160). The pressure was reduced for 20 seconds to 13 hPa or less, and the upper and lower plates were heated to 80°C and 60°C, respectively, and then the sheets were compressed at atmospheric pressure for 20 seconds. This is referred to as resin sheet A with a laminated resin layer.

[0182] In Example 3, the liquid crystal polymer film (Vecstar-FCCL:CTF-25, manufactured by Kuraray Co., Ltd.) was replaced with a flexible polyimide copper-clad laminate (ESPANEX:MC12-25-00HRM, manufactured by Nippon Steel Chemical Co., Ltd.), and the polyimide film was laminated so as to be in contact with the resin composition layer.

[0183] (3) Laminating a resin sheet laminated with a resin layer and a silicon wafer The support was peeled off from each resin sheet A with the resin layer laminated thereon, and the resin composition layer was laminated onto one side of the wafer using a batch-type vacuum pressure laminator (Nikko Materials Co., Ltd., two-stage build-up laminator, CVP700) so that the resin composition layer was in contact with the silicon wafer. Lamination was performed by reducing the pressure to 13 hPa or less for 30 seconds, and then pressing the wafer at 130°C and a pressure of 0.74 MPa for 45 seconds. The wafer was then heat-pressed at 120°C and a pressure of 0.5 MPa for 75 seconds.

[0184] (4) Thermal curing of the resin composition layer The silicon wafer laminated with the resin sheet was placed in a 100°C oven for 30 minutes, then transferred to a 180°C oven for 30 minutes to heat cure the resin sheet and form an insulating layer. This resulted in Substrate A, with a total thickness of 40 μm for the insulating layer and resin layer. At this time, the copper in the flexible copper-clad laminate was etched out using iron (III) chloride.

[0185] (5) Dry film pattern formation A 20 μm thick dry film (Nikko Materials Co., Ltd., "ALPHO 20A263") was laminated onto the surface of the resin layer of Substrate A. The dry film was laminated using a batch-type vacuum pressure laminator (Meiki Seisakusho Co., Ltd., "MVLP-500"), which was depressurized for 30 seconds to a pressure of 13 hPa or less, and then pressurized at a pressure of 0.1 MPa and a temperature of 70°C for 20 seconds. A glass mask with a via pattern was then placed on the polyethylene terephthalate film, which was the protective layer for the dry film, and a UV lamp was used to irradiate the film at an irradiation intensity of 150 mJ / cm. 2 After UV irradiation, the substrate was sprayed with a 1% sodium carbonate aqueous solution at 30°C at a spray pressure of 0.15 MPa for 30 seconds.

[0186] (6) Plasma processing In Examples 1 to 3, a vacuum plasma etching device (M120W manufactured by Nissin Co., Ltd.) was used to perform processing for 40 minutes under conditions of a CF4 / O2 mixture ratio of 1:7 (sccm) and a pressure of 120 Pa, forming via holes with a top diameter of approximately 40 μm in the resin layer of the via-processed substrate, and then the dry film was peeled off to obtain a via evaluation substrate.

[0187] (7) UV-YAG laser via processing In Comparative Example 3, a UV-YAG laser processing machine ("LU-2L212 / M50L" manufactured by Via Mechanics) was used to irradiate the resin layer of Substrate A with laser light to form multiple via holes with a top diameter of approximately 40 μm. The laser light irradiation conditions were a power of 0.8 W and 50 shots. This substrate was used as a laser evaluation substrate.

[0188] The laser evaluation substrate was immersed in a swelling solution (Atotech Japan's "Swelling Dip Securigant P," an aqueous solution of diethylene glycol monobutyl ether and sodium hydroxide) at 60°C for 5 minutes. It was then immersed in a roughening solution (Atotech Japan's Concentrate Compact P (aqueous solution of KMnO4: 60 g / L, NaOH: 40 g / L)) at 80°C for 15 minutes. Finally, it was immersed in a neutralizing solution (Atotech Japan's Reduction Showreusin Securigant P (aqueous solution of sulfuric acid)) at 40°C for 5 minutes. It was then dried at 80°C for 30 minutes.

[0189] <Observation of via hole cross section> The via evaluation board and laser evaluation board were heated at 150°C for 30 minutes, and then a copper layer (200 nm thick) was formed on the resin layer using a sputtering device (Canon Anelva "E-400S"). The cross section was then observed using a FIB-SEM hybrid device (SII Nano Technology "SMI3050SE") to determine [d / {(1 / 2) × a}] × 100. Evaluation was also based on the following criteria. Good: [d / {(1 / 2)×a}]×100 is less than 5%. ×: [d / {(1 / 2)×a}]×100 exceeds 5%.

[0190] <Observation of via hole walls> The via evaluation substrate and laser evaluation substrate were heated at 150°C for 30 minutes, and then a copper layer (200 nm thick) was formed on the insulating layer using a sputtering device (Canon Anelva's "E-400S"). Cross-sections were then observed using a FIB-SEM hybrid device (SII Nano Technology's "SMI3050SE") and evaluated according to the following criteria. ◯: A copper layer is formed uniformly and without interruption on the wall surfaces of the via holes formed in the insulating layer and the resin layer. ×: The copper layer was not formed uniformly due to irregularities.

[0191] <Evaluation of lamination> Resin sheet A with a resin layer was cut to a size appropriate for laminating onto a silicon wafer, and evaluated according to the following criteria. ◯: No lifting is observed around the cut due to insufficient adhesion between the resin layer and the resin composition layer from the cut portion. ×: Lifting was observed around the cut area due to insufficient adhesion between the resin layer and the resin composition layer.

[0192] <Measurement of coefficient of linear thermal expansion (CTE)> (Preparation of cured product for evaluation) A glass cloth-based epoxy resin double-sided copper-clad laminate (Matsushita Electric Works, Ltd., "R5715ES," thickness 0.7 mm, 255 mm square) was placed on the release agent-untreated side of a release agent-treated PET film ("501010," manufactured by Lintec Corporation, thickness 38 μm, 240 mm square), and the four sides were fixed with polyimide adhesive tape (width 10 mm) (hereinafter referred to as "fixed PET film").

[0193] Resin compositions 1 to 3 were applied to a PET film (Toray Industries, Inc., "Lumirror R80," 38 μm thick, softening point 130°C, hereafter referred to as "release PET") that had been treated with an alkyd resin release agent ("AL-5," manufactured by Lintec Corporation) using a die coater to a thickness of 40 μm after drying. The film was then dried at 80°C to 120°C (average 100°C) for 10 minutes to obtain resin sheets. Each resin sheet (40 μm thick, 200 mm square) was centrally laminated to the release-treated surface of the fixed PET film using a batch-type vacuum pressure laminator (Nikko Materials Co., Ltd., two-stage build-up laminator, CVP700) to obtain resin sheets. The lamination was performed by reducing the pressure to 13 hPa or less for 30 seconds, followed by pressure bonding at 100°C and a pressure of 0.74 MPa for 30 seconds.

[0194] Next, the release PET was peeled off from the resin sheet with the support, and the sheet was placed in an oven at 190° C. and thermally cured for 1.5 hours.

[0195] After thermal curing, the polyimide adhesive tape was peeled off, and the cured product was removed from the glass cloth-based epoxy resin double-sided copper-clad laminate. The PET film ("501010" manufactured by Lintec Corporation) was also peeled off, yielding a sheet-like cured product, which is referred to as the "cured product for evaluation."

[0196] The cured product for evaluation was cut into test pieces measuring 5 mm in width and 15 mm in length, and thermomechanical analysis was performed using a thermomechanical analyzer (TMA, SS6100) manufactured by Seiko Instruments Inc. using the tensile load method. Specifically, the test pieces were mounted in the thermomechanical analyzer, and measurements were performed twice consecutively under the measurement conditions of a load of 1 g and a heating rate of 5°C / min. The linear thermal expansion coefficient (ppm / °C) in the planar direction over the temperature range from 25°C to 150°C was calculated from the two measurements.

[0197] [Table 2]

[0198] In Comparative Examples 1 and 2, the resin composition layer and the resin layer of the resin sheet could not be laminated, and therefore the top diameter of the via holes and the like could not be observed or measured. [Explanation of symbols]

[0199] 1. Printed wiring board 2. Inner layer circuit board 3. Insulation layer 4 Resin layer 4a 1st page 4b Side 2 41 Edge of the first surface inside the via hole 42 Edge of contact surface between first surface and insulating layer 5 Conductor layer 6. Beer Hall a Top diameter d Step distance

Claims

1. A printed wiring board comprising, in this order, a resin layer having a first surface, an insulating layer in contact with the first surface of the resin layer and including a cured product of a resin composition, and an inner layer circuit board, the resin layer is formed of a thermoplastic resin, The resin composition includes a thermosetting resin, a via hole penetrating the resin layer and the insulating layer in a thickness direction; The top diameter of the via hole is a (μm), When the distance from the end of the first surface in the via hole to the end of the contact surface between the first surface and the insulating layer is d (μm), A printed wiring board that satisfies the relationship: 0.5≦[d / {(1 / 2)×a}]×100≦5.

2. A printed wiring board comprising, in this order, a resin layer having a first surface, an insulating layer in contact with the first surface of the resin layer and including a cured product of a resin composition, and an inner layer circuit board, the resin layer is formed of a thermoplastic resin, The resin composition includes a thermosetting resin, a via hole penetrating the resin layer and the insulating layer in a thickness direction; The top diameter of the via hole is a (μm), When the distance from the end of the first surface in the via hole to the end of the contact surface between the first surface and the insulating layer is d (μm), The relationship 0.5≦[d / {(½)×a}]×100≦5 is satisfied, a printed wiring board, wherein, when cut along a plane parallel to the inner layer circuit board, the diameter of the via hole penetrating the insulating layer on the first surface side and the diameter of the via hole on the inner layer circuit board side are larger than the diameter of the via hole penetrating the resin layer on the second surface side and the diameter of the via hole on the first surface side, respectively.

3. 3. The printed wiring board according to claim 1, wherein the top diameter of the via hole is 50 [mu]m or less.

4. The printed wiring board according to any one of claims 1 to 3, wherein the resin composition contains an inorganic filler.

5. 5. The printed wiring board according to claim 4, wherein the content of the inorganic filler is 50% by mass or less when the nonvolatile components of the resin composition are taken as 100% by mass.

6. The printed wiring board according to any one of claims 1 to 5, wherein the linear thermal expansion coefficient of the cured product of the resin composition is 40 ppm or less.

7. 7. The printed wiring board according to claim 1, wherein the resin layer contains either a polyimide resin or a liquid crystal polymer.

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