Circuit board manufacturing method

Abstract

The present invention provides a novel method for producing a circuit board that makes it possible, in production of a circuit board in which chemical-mechanical polishing is performed on an insulation layer, to achieve a high polishing speed and produce an insulation layer with little surface roughness. The method for producing a circuit board is characterized by comprising: a step (X) for forming, on a base material to a surface of which is provided a conductor pillar for interlayer connection, a resin composition layer of a resin composition R, such that the conductor pillar is embedded, and curing the resin composition layer to form an insulation layer; a step (Y) for polishing the insulation layer via chemical-mechanical polishing (CMP) so as to expose the conductor pillar; and a step (Z) for forming a plating seed layer on a surface of the insulation layer, wherein step (X) is performed such that the expression 0.5≤Tg1 / Tg2≤0.9 is satisfied, where Tg1 is the glass transition temperature (°C) of a cured product obtained by curing the resin composition R under the curing conditions in step (X), and Tg2 is the glass transition temperature (°C) of a cured product obtained by curing the resin composition R for 120 minutes at 200°C.

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing a circuit board. [Background technology]

[0002] In the manufacture of semiconductor packages such as wafer level packages (WLPs) and panel level packages (PLPs), circuit boards such as rewiring boards are generally formed by applying a curable resin material to a wafer or panel substrate, curing it to form an insulating layer, then forming a conductor layer on the insulating layer, and repeating this process to create multiple layers (e.g., Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-015191 Summary of the Invention [Problem to be solved by the invention]

[0004] As electronic devices become more sophisticated, circuit boards used in semiconductor packages are required to have finer wiring. Chemical-mechanical polishing (CMP), a proven precision polishing technique for forming fine wiring, is expected to be a promising technology for manufacturing circuit boards by polishing an insulating layer and then forming a conductor layer on the resulting polished surface of the insulating layer. The surface of the insulating layer (polished surface) after CMP is flat and smooth, which can contribute to the finer conductor layer formed on it.

[0005] On the other hand, in order to increase the productivity of semiconductor packages, efforts are being made to speed up each production process, and this has led to a demand for faster chemical mechanical polishing of insulating layers. Increasing the polishing speed during chemical mechanical polishing of insulating layers by adjusting the polishing conditions (rotation speed, pressure, type and concentration of abrasive) increases the surface roughness of the resulting insulating layer, thereby negating the benefits of chemical mechanical polishing. Furthermore, insulating layers used in circuit boards often contain inorganic fillers such as silica to achieve properties such as a low thermal expansion coefficient and a low dielectric loss tangent. In such cases, the above-mentioned problems have been found to be more pronounced. Specifically, we have found that increasing the polishing speed during chemical mechanical polishing of insulating layers containing inorganic fillers increases the surface roughness of the resulting insulating layer, due to the inorganic filler being removed from the surface of the insulating layer and causing depressions on the surface.

[0006] The present invention provides a novel method for manufacturing a circuit board, which can achieve a high polishing rate and produce an insulating layer with low surface roughness in the manufacture of a circuit board by chemically mechanically polishing an insulating layer. That is, the present invention provides a novel technique for achieving both high polishing speed and the formation of an insulating layer with low surface roughness, which have been difficult to achieve in the past in the manufacture of a circuit board by chemically mechanically polishing an insulating layer. [Means for solving the problem]

[0007] As a result of extensive research into solving the above problems, the present inventors have found that the above problems can be solved by a method for manufacturing a circuit board having the following configuration, and have thus completed the present invention.

[0008] That is, the present invention includes the following. <1> The following steps (X), (Y) and (Z): (X) forming a resin composition layer from the resin composition R on a substrate having conductive pillars for interlayer connection on its surface so as to embed the conductive pillars, and curing the resin composition layer to form an insulating layer; (Y) polishing the insulating layer by chemical mechanical polishing (CMP) to expose the conductor pillars; and (Z) A process for forming a plating seed layer on the surface of the insulating layer A method for manufacturing a circuit board, comprising: A method for manufacturing a circuit board, wherein step (X) is carried out so that 0.5≦Tg1 / Tg2≦0.9 is satisfied, where Tg1 is the glass transition temperature (°C) of a cured product obtained by curing resin composition R under the curing conditions in step (X), and Tg2 is the glass transition temperature (°C) of a cured product obtained by curing resin composition R at 200°C for 120 minutes. <2> In step (Z), a plating seed layer is formed by a sputtering method. <1> The method described below. <3> The step (X) includes laminating a resin sheet including a support and a resin composition layer provided on the support onto a substrate so that the resin composition layer is bonded to the conductor pillar. <1> or <2> The method described below. <4> The polishing amount (thickness) of the insulating layer in step (Y) is 1 μm or more. <1> ~ <3> A method according to any one of the above. <5> The polishing rate of the insulating layer in step (Y) is 1 μm / min or more. <1> ~ <4> A method according to any one of the above. <6> the arithmetic mean roughness Ra of the polished surface of the insulating layer obtained in step (Y) is 70 nm or less; <1> ~ <5> A method according to any one of the above. <7> The thickness of the plating seed layer formed in step (Z) is 500 nm or less. <1> ~ <6> A method according to any one of the above. <8> forming a conductor layer on the plating seed layer by electroplating; <1> ~ <7> A method according to any one of the above. <9> The resin composition R contains a thermosetting resin. <1> ~ <8> A method according to any one of the above. <10> The content of the inorganic filler in the resin composition R is 40% by mass or more, when the non-volatile components in the resin composition R are 100% by mass. <1> ~ <9> A method according to any one of the above. <11> The resin composition R contains an inorganic filler treated with an alkoxy group-containing surface treatment agent. <1> ~ <10> A method according to any one of the above. <12> The alkoxy group-containing surface treatment agent is at least one selected from the group consisting of an alkoxy group-containing silane coupling agent and an oligomer thereof. <11> The method described below. <13> The amount of carbon per unit surface area of ​​the inorganic filler is 0.05 mg / m 2 That's all. <11> or <12> The method described below. <14> Tg2 is 150°C or higher, <1> ~ <13> A method according to any one of the above. <15> The circuit board is for a semiconductor package. <1> ~ <14> A method according to any one of the above. [Effects of the Invention]

[0009] According to the present invention, a novel method for manufacturing a circuit board can be provided that can achieve a high polishing rate and produce an insulating layer with low surface roughness in the manufacture of a circuit board by chemically mechanically polishing an insulating layer. That is, the present invention can provide a novel technique that can achieve both high polishing speed and the formation of an insulating layer with low surface roughness, which have been difficult to achieve in the past in the manufacture of a circuit board by chemically mechanically polishing an insulating layer. DETAILED DESCRIPTION OF THE INVENTION

[0010] Before describing the method for producing a circuit board of the present invention in detail, the resin composition ("resin composition R") used in the production method of the present invention will be described.

[0011] <Resin composition> In the method for producing a circuit board of the present invention, a resin composition layer is formed from a resin composition R so as to embed conductor pillars for interlayer connection, and the resin composition layer is cured to form an insulating layer. Here, the resin composition R is not particularly limited as long as it can be formed so as to embed the conductor pillars and exhibits sufficient insulating properties after curing. Preferred embodiments will be described below from the perspective of better enjoying the effects of the present invention.

[0012] From the viewpoint of being able to provide a cured product that exhibits good insulating properties and good heat resistance, the resin composition R contains (a) a curable resin, and may further contain, as necessary, one or more selected from the group consisting of (b) a curing agent, (c) an inorganic filler, (d) a thermoplastic resin, and (e) a curing accelerator. Each component that can be contained in the resin composition will be described below.

[0013] -(a) Curing resin- The curable resin may be any known curable resin used in forming an insulating layer of a circuit board. The method for producing a circuit board of the present invention can achieve both high polishing speed and formation of an insulating layer with low surface roughness, regardless of the type of curable resin.

[0014] From the viewpoint of being able to provide a cured product that exhibits both good insulating properties and heat resistance, the curable resin is preferably one or more selected from the group consisting of thermosetting resins and radically polymerizable resins.

[0015] Examples of thermosetting resins include epoxy resins, polyarylene ether resins, benzocyclobutene resins, epoxy acrylate resins, urethane acrylate resins, urethane resins, cyanate resins, melamine resins, and silicone resins. One type of thermosetting resin may be used alone, or two or more types may be used in combination. Among these, the curable resin preferably contains an epoxy resin, from the viewpoint of being able to provide a cured product that exhibits both good insulating properties and good heat resistance.

[0016] The type of epoxy resin is not particularly limited as long as it has one or more (preferably two or more) epoxy groups per molecule. Examples of epoxy resins include bisphenol A epoxy resins, bisphenol F epoxy resins, bisphenol S epoxy resins, bisphenol AF epoxy resins, phenol novolac epoxy resins, tert-butyl-catechol epoxy resins, naphthol epoxy resins, naphthalene epoxy resins, naphthylene ether epoxy resins, glycidylamine epoxy resins, glycidyl ester epoxy resins, cresol novolac epoxy resins, biphenyl epoxy resins, phenol aralkyl epoxy resins, biphenyl aralkyl epoxy resins, fluorene skeleton epoxy resins, dicyclopentadiene epoxy resins, anthracene epoxy resins, linear aliphatic epoxy resins, epoxy resins having a butadiene structure, alicyclic epoxy resins, heterocyclic epoxy resins, spiro ring-containing epoxy resins, cyclohexanedimethanol epoxy resins, trimethylol epoxy resins, and halogenated epoxy resins.

[0017] Epoxy resins can be classified into epoxy resins that are liquid at a temperature of 20°C (hereinafter referred to as "liquid epoxy resins") and epoxy resins that are solid at a temperature of 20°C (hereinafter referred to as "solid epoxy resins"). Resin composition R may contain only liquid epoxy resins as the curable resin, only solid epoxy resins, or a combination of liquid and solid epoxy resins. When a combination of liquid and solid epoxy resins is contained, the blending ratio (liquid:solid) may be in the range of 20:1 to 1:20 (preferably 10:1 to 1:10, more preferably 3:1 to 1:3) by mass.

[0018] The epoxy group equivalent of the epoxy resin is preferably 50 g / eq. to 2000 g / eq., more preferably 60 g / eq. to 1000 g / eq., and even more preferably 80 g / eq. to 500 g / eq. The epoxy group equivalent is the mass of the epoxy resin containing one equivalent of epoxy groups, and can be measured in accordance with JIS K7236.

[0019] The weight average molecular weight (Mw) of the epoxy resin is preferably 100 to 5,000, more preferably 250 to 3,000, and even more preferably 400 to 1,500. The Mw of the epoxy resin can be measured as a polystyrene-equivalent value by gel permeation chromatography (GPC).

[0020] The polyarylene ether resin is not particularly limited in type as long as it has a polyarylene ether skeleton and exhibits crosslinkability through reaction of functional groups such as terminal hydroxyl groups. Examples of polyarylene ether resins include polyphenylene ether resins and polynaphthylene ether resins, which may be homopolymers or copolymers. Examples of homopolymers of polyphenylene ether resins include 2,6-diC 1~3 Examples of the copolymer include those containing alkyl-1,4-phenylene ether units, and examples of the copolymer include 2,6-diC 1~3 Alkyl-1,4-phenylene ether unit with 2,3,6-triC 1~3 Examples of suitable polyarylene ether resins include graft, block, and random copolymers containing a combination of alkyl-1,4-phenylene ether units, etc. Examples of suitable polyarylene ether resins include Noryl (registered trademark) SA90 manufactured by SABIC.

[0021] The number average molecular weight (Mn) of the polyarylene ether resin is preferably from 200 to 5000, more preferably from 400 to 3000, and even more preferably from 600 to 2500. The Mn of the polyarylene ether resin can be measured by the GPC method as a polystyrene-equivalent value.

[0022] The type of radical polymerizable resin is not particularly limited as long as it has one or more (preferably two or more) radical polymerizable unsaturated groups in one molecule. Examples of radical polymerizable resins include resins having one or more radical polymerizable unsaturated groups selected from maleimide groups, vinyl groups, allyl groups, styryl groups, vinylphenyl groups, acryloyl groups, methacryloyl groups, fumaroyl groups, and maleoyl groups. Among these, from the viewpoint of being able to produce a cured product that exhibits both good insulating properties and good heat resistance, it is preferred that the curable resin contain one or more selected from maleimide resins, (meth)acrylic resins, and styryl resins.

[0023] The type of maleimide resin is not particularly limited as long as it has one or more (preferably two or more) maleimide groups (2,5-dihydro-2,5-dioxo-1H-pyrrol-1-yl groups) in one molecule. Examples of maleimide resins include maleimide resins having an aliphatic skeleton (preferably an aliphatic skeleton containing a cyclic structure having 10 or more carbon atoms, more preferably an aliphatic skeleton having 36 carbon atoms derived from dimer diamine), such as "BMI-3000J," "BMI-5000," "BMI-1400," "BMI-1500," "BMI-1700," and "BMI-689" (all manufactured by Designer Molecules Inc.); maleimide resins having an indane skeleton, as described in the Japan Institute of Invention and Innovation Disclosure Technical Bulletin No. 2020-500211; and maleimide resins having an aromatic ring skeleton directly bonded to the nitrogen atom of the maleimide group, such as "MIR-3000-70MT" (manufactured by Nippon Kayaku Co., Ltd.), "BMI-4000," "BMI-1000" (manufactured by Daiwa Kasei Co., Ltd.), and "BMI-80" (manufactured by Keiai Kasei Co., Ltd.).

[0024] The (meth)acrylic resin may be a monomer or an oligomer, and may be any type of (meth)acrylic resin, as long as it has one or more (preferably two or more) (meth)acryloyl groups in one molecule. Here, the term "(meth)acryloyl group" is a general term for acryloyl groups and methacryloyl groups. Examples of methacrylic resins include (meth)acrylate monomers, as well as (meth)acrylic resins such as "A-DOG" (manufactured by Shin-Nakamura Chemical Co., Ltd.), "DCP-A" (manufactured by Kyoeisha Chemical Co., Ltd.), "NPDGA," "FM-400," "R-687," "THE-330," "PET-30," and "DPHA" (all manufactured by Nippon Kayaku Co., Ltd.).

[0025] The styryl resin may be a monomer or an oligomer, and may be any type, as long as it contains one or more (preferably two or more) styryl or vinylphenyl groups per molecule. Examples of the styryl resin include "OPE-2St," "OPE-2St 1200," and "OPE-2St 2200" (all manufactured by Mitsubishi Gas Chemical Company, Inc.). Examples of the styryl resin include, in addition to styrene monomers, homopolymers of aromatic divinyl compounds such as divinylbenzene, 2,4-divinyltoluene, 2,6-divinylnaphthalene, 1,4-divinylnaphthalene, 4,4'-divinylbiphenyl, 1,2-bis(4-vinylphenyl)ethane, 2,2-bis(4-vinylphenyl)propane, and bis(4-vinylphenyl)ether, as well as copolymers of these aromatic divinyl compounds with aromatic monovinyl compounds such as styrene, vinyltoluene, ethylstyrene, and vinylnaphthalene.

[0026] The resin composition R may contain only a thermosetting resin as the curable resin, may contain only a radically polymerizable resin, or may contain a combination of a thermosetting resin and a radically polymerizable resin. In one embodiment, the resin composition R contains a thermosetting resin.

[0027] From the viewpoint of providing a cured product exhibiting both good insulating properties and good heat resistance, and from the viewpoint of being able to enjoy the effects of the present invention more effectively, the content of the curable resin in the resin composition is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 12% by mass or more, 14% by mass or more, or 15% by mass or more, when the resin components in the resin composition are taken as 100% by mass. The upper limit of the content is not particularly limited and may be determined depending on the properties required of the resin composition, and may be 100% by mass, but may also be, for example, 90% by mass or less, 80% by mass or less, 70% by mass or less, or 60% by mass or less.

[0028] In the present invention, the term "resin component" in relation to the resin composition refers to the non-volatile components constituting the resin composition excluding the inorganic filler described below.

[0029] -(b) Hardener- The resin composition R may further contain a curing agent. The curing agent is not particularly limited as long as it has the function of curing the curable resin, and examples thereof include phenol-based curing agents, naphthol-based curing agents, active ester-based curing agents, acid anhydride-based curing agents, benzoxazine-based curing agents, cyanate ester-based curing agents, carbodiimide-based curing agents, and amine-based curing agents. One type of curing agent may be used alone, or two or more types may be used in combination.

[0030] As the phenol-based curing agent and naphthol-based curing agent, from the viewpoint of heat resistance and water resistance, a phenol-based curing agent having a novolac structure or a naphthol-based curing agent having a novolac structure is preferred. Furthermore, from the viewpoint of achieving an insulating layer having good adhesion strength (peel strength) with the conductor layer, a nitrogen-containing phenol-based curing agent or a nitrogen-containing naphthol-based curing agent is preferred, and a triazine skeleton-containing phenol-based curing agent or a triazine skeleton-containing naphthol-based curing agent is more preferred. Among them, from the viewpoint of highly satisfying heat resistance, water resistance, and adhesion strength with the conductor layer, a triazine skeleton-containing phenol novolac resin is preferred.

[0031] Specific examples of phenol-based curing agents and naphthol-based curing agents include "MEH-7700," "MEH-7810," "MEH-7851," and "MEH-8000H" manufactured by Meiwa Chemical Industry Co., Ltd.; "NHN," "CBN," and "GPH" manufactured by Nippon Kayaku Co., Ltd.; and "SN-170," "SN-180," "SN-190," "SN-475," "SN-485," "SN-495," "SN-495V," and "SN-37" manufactured by Nippon Steel Chemical & Material Co., Ltd. 5" and "SN-395" manufactured by DIC Corporation; "TD-2090", "TD-2090-60M", "LA-7052", "LA-7054", "LA-1356", "LA-3018", "LA-3018-50P", "EXB-9500", "HPC-9500", "KA-1160", "KA-1163", and "KA-1165" manufactured by Gun-ei Chemical Co., Ltd.; and "GDP-6115L", "GDP-6115H", and "ELPC75" manufactured by Gun-ei Chemical Co., Ltd.

[0032] As the active ester curing agent, a compound having one or more active ester groups per molecule can be used. Among them, preferred active ester curing agents are compounds 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 curing agent 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 curing agents derived from carboxylic acid compounds are preferred, active ester curing agents obtained from a carboxylic acid compound and a hydroxy compound are more preferred, and active ester curing agents obtained from a carboxylic acid compound and an aromatic hydroxy compound are even more preferred.

[0033] The carboxylic acid compound may be either an aromatic carboxylic acid compound or an aliphatic carboxylic acid, and examples thereof include benzoic acid, acetic acid, succinic acid, maleic acid, itaconic acid, phthalic acid, isophthalic acid, terephthalic acid, and pyromellitic acid.

[0034] Examples of aromatic hydroxy compounds include (i) polyaddition products of unsaturated aliphatic cyclic compounds containing two double bonds per molecule with phenols, (ii) various bisphenol compounds, (iii) aromatic polyols having two or more hydroxy groups bonded to a carbon atom on an aromatic ring, and (iv) aromatic monools having one hydroxy group bonded to a carbon atom on an aromatic ring. Examples of polyaddition products of unsaturated aliphatic cyclic compounds with phenols include polyaddition products of unsaturated aliphatic cyclic compounds such as dicyclopentadiene, tetrahydroindene, norbornadiene, limonene, and vinylcyclohexene with optionally substituted phenols (e.g., phenol, cresol, xylenol, ethylphenol, propylphenol, vinylphenol, allylphenol, phenylphenol, benzylphenol, and halophenols), and specific examples thereof include dicyclopentadiene-phenol polyaddition products. Examples of bisphenol compounds include bisphenol A, bisphenol F, bisphenol AF, bisphenol AP, bisphenol B, bisphenol BP, bisphenol C, and bisphenol M. Examples of aromatic polyols in which two or more hydroxy groups are bonded to carbon atoms on an aromatic ring include hydroquinone, resorcinol, catechol, 1,5-dihydroxynaphthalene, 1,6-dihydroxynaphthalene, 2,6-dihydroxynaphthalene, dihydroxybenzophenone, trihydroxybenzophenone, tetrahydroxybenzophenone, phloroglucinol, benzenetriol, and phenol novolak. Examples of aromatic monools having one hydroxy group bonded to a carbon atom on an aromatic ring include phenol, cresol, xylenol, ethylphenol, propylphenol, vinylphenol, allylphenol, phenylphenol, benzylphenol, halophenols, naphthol, methylnaphthol, dimethylnaphthol, ethylnaphthol, propylnaphthol, vinylnaphthol, allylnaphthol, phenylnaphthol, benzylnaphthol, and halonaphthol.

[0035] Specific examples of suitable active ester curing agents include active ester compounds containing a dicyclopentadiene-type diphenol structure, active ester compounds containing a naphthalene structure, active ester compounds containing an acetylated product of phenol novolac, and active ester compounds containing a benzoylated product of phenol novolac. Among these, active ester compounds containing a naphthalene structure and active ester compounds containing a dicyclopentadiene-type diphenol structure are more preferred. The "dicyclopentadiene-type diphenol structure" refers to a divalent structural unit consisting of phenylene-dicyclopentalene-phenylene.

[0036] Commercially available active ester curing agents include active ester resins containing a dicyclopentadiene-type diphenol structure, such as "EXB-9451," "EXB-9460," "EXB-9460S," "HPC-8000-65T," "HPC-8000H-65TM," and "HPC-8000L-65TM" (manufactured by DIC Corporation); active ester resins containing a naphthalene structure, such as "EXB-8100L-65T," "EXB-8150-60T," "EXB-8150-62T," "EXB-9416-70BK," "HPC-8150-60T," and "HPC-8150-62T"; Examples of such active ester resins include "HP-B-8151-62T" and "HP-C-8151-62T" (manufactured by DIC Corporation); "EXB9401" (manufactured by DIC Corporation) as a phosphorus-containing active ester resin; "DC808" (manufactured by Mitsubishi Chemical Corporation) as an active ester resin which is an acetylated product of phenol novolac; "YLH1026," "YLH1030," and "YLH1048" (manufactured by Mitsubishi Chemical Corporation) as active ester resins which are benzoylated products of phenol novolac; and "PC1300-02-65MA" (manufactured by Air Water Inc.) as an active ester resin containing a styryl group and a naphthalene structure.

[0037] Examples of acid anhydride curing agents include curing agents having one or more acid anhydride groups in one molecule. Specific examples of acid anhydride curing agents 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 acid anhydrides include 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 acid anhydrides such as styrene-maleic acid resins (copolymers of styrene and maleic acid). Commercially available acid anhydride curing agents include "MH-700" manufactured by New Japan Chemical Co., Ltd.

[0038] Specific examples of benzoxazine-based curing agents 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.

[0039] Examples of cyanate ester curing agents 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-cyanatephenylmethane), bis(4-cyanate-3,5-dimethylphenyl)methane, 1,3-bis(4-cyanatephenyl-1-(methylethylidene))benzene, bis(4-cyanatephenyl)thioether, and bis(4-cyanatephenyl)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 curing agents include "PT30" 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 triazine converted to a trimer), all of which are manufactured by Arxada.

[0040] Specific examples of carbodiimide curing agents include Carbodilite (registered trademark) V-03 (carbodiimide group equivalent: 216 g / eq.), V-05 (carbodiimide group equivalent: 262 g / eq.), V-07 (carbodiimide group equivalent: 200 g / eq.), and V-09 (carbodiimide group equivalent: 200 g / eq.), all manufactured by Nisshinbo Chemical Inc.; and Stavaxol (registered trademark) P (carbodiimide group equivalent: 302 g / eq.) manufactured by Lanxess AG.

[0041] Examples of the amine-based curing agent include curing agents having one or more amino groups in one molecule, such as aliphatic amines, polyether amines, alicyclic amines, and aromatic amines. Specific examples of the amine-based curing agent 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 curing agents include 4,4'-bis(4-aminophenoxy)biphenyl, bis(4-(4-aminophenoxy)phenyl)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 curing agents 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.

[0042] When the resin composition R contains a curing agent, the content of the curing agent is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 15% by mass or more, based on 100% by mass of the resin component in the resin composition. The upper limit of the content of the curing agent is preferably 60% by mass or less, more preferably 50% by mass or less, or 40% by mass or less.

[0043] -(c) Inorganic filler- The resin composition R may further contain an inorganic filler. By including an inorganic filler, an insulating layer having a low linear thermal expansion coefficient and a low dielectric loss tangent can be realized.

[0044] Examples of inorganic filler materials include silica, alumina, glass, cordierite, silicon oxide, barium sulfate, barium carbonate, talc, clay, mica powder, zinc oxide, hydrotalcite, boehmite, aluminum silicate, 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, silica is particularly preferred. Examples of silica include amorphous silica, fused silica, crystalline silica, synthetic silica, and hollow silica. Spherical silica is preferred. The inorganic fillers may be used alone or in combination of two or more.

[0045] Commercially available inorganic fillers include, for example, "UFP-30" manufactured by Denka Chemical Industry Co., Ltd.; "SP60-05" and "SP507-05" manufactured by Nippon Steel Chemical & Material Co., Ltd.; "YC100C", "YA050C", "YA050C-MJE", and "YA010C" manufactured by Admatechs Co., Ltd.; "UFP-30" manufactured by Denka Company Limited; "Silfil NSS-3N", "Silfil NSS-4N", and "Silfil NSS-5N" manufactured by Tokuyama Corporation; "SC2500SQ", "SO-C4", "SO-C2", and "SO-C1" manufactured by Admatechs Co., Ltd.; "DAW-03" and "FB-105FD" manufactured by Denka Company Limited; "Cellphears" and "MGH-005" manufactured by Taiheiyo Cement Corporation; and "Sferique" and "BA-1" manufactured by JGC Catalysts and Chemicals Co., Ltd.

[0046] The average particle size of the inorganic filler is not particularly limited, but is preferably 5 μm or less, more preferably 3 μm or less, 2 μm or less, 1 μm or less, or 0.7 μm or less. The lower limit of the average particle size is not particularly limited, but is preferably 0.01 μm or more, more preferably 0.05 μm or more, and even more preferably 0.07 μm or more, 0.1 μm or more, or 0.2 μm or more. The average particle size of the inorganic filler can be measured by a laser diffraction / scattering method based on Mie scattering theory. Specifically, a particle size distribution of the inorganic filler is prepared on a volume basis 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 the inorganic filler and 10 g of methyl ethyl ketone into a vial and ultrasonically dispersing the mixture for 10 minutes. The measurement sample was measured using a laser diffraction particle size distribution analyzer, with blue and red light source wavelengths used, and the particle size distribution of the inorganic filler on a volume basis was measured using a flow cell system, and the average particle size was calculated as the median diameter from the particle size distribution obtained. An example of a laser diffraction particle size distribution analyzer is the "LA-960" manufactured by Horiba, Ltd.

[0047] The specific surface area of ​​the inorganic filler is not particularly limited, but is preferably 0.1 m 2 / g or more, more preferably 0.5m 2 / g or more, more preferably 1m 2 / g or more, 3m 2 / g or more or 5m 2 The upper limit of the specific surface area is not particularly limited, but is preferably 100 m 2 / g or less, more preferably 80m 2 / g or less, more preferably 60m 2 / g or less, 50m 2 / g or less or 40m 2 The specific surface area of ​​the inorganic filler is obtained according to the BET method by adsorbing nitrogen gas onto the surface of the sample using a specific surface area measuring device (Macsorb HM-1210 manufactured by Mountech Co., Ltd.) and calculating the specific surface area using the BET multipoint method.

[0048] The inorganic filler is preferably surface-treated with an appropriate surface treatment agent. Surface treatment can improve the moisture resistance and dispersibility of the inorganic filler. Examples of surface treatment agents include silane coupling agents such as vinyl silane coupling agents, epoxy silane coupling agents, styryl silane coupling agents, (meth)acrylic silane coupling agents, amino silane coupling agents, isocyanurate silane coupling agents, ureido silane coupling agents, mercapto silane coupling agents, isocyanate silane coupling agents, and acid anhydride silane coupling agents; alkoxysilane compounds such as methyltrimethoxysilane and phenyltrimethoxysilane; silazane compounds; and oligomers thereof. One type of surface treatment agent may be used alone, or two or more types may be used in combination.

[0049] In particular, in the production of circuit boards in which the insulating layer is chemically mechanically polished, from the viewpoint of being able to provide an insulating layer with even smaller surface roughness, the surface treatment agent is preferably an alkoxy group-containing surface treatment agent, and more preferably is one or more selected from the group consisting of alkoxy group-containing silane coupling agents and their oligomers (hereinafter also referred to as "alkoxy oligomers").

[0050] As the alkoxy group-containing silane coupling agent, from the viewpoint of being able to enjoy the effects of the present invention more effectively, a silane coupling agent having, in addition to an alkoxy group, one or more functional groups selected from the group consisting of an amino group, an epoxy group, and a mercapto group is preferred. These may be used alone or in combination of two or more. The alkoxy group-containing silane coupling agent may have one or more functional groups.

[0051] Specific examples of such silane coupling agents include aminosilane-based alkoxy group-containing silane coupling agents such as aminopropyl methoxysilane, aminopropyl triethoxysilane, ureidopropyl triethoxysilane, N-phenyl-3-aminopropyl trimethoxysilane, and N-2(aminoethyl)aminopropyl trimethoxysilane; epoxysilane-based alkoxy group-containing silane coupling agents such as glycidoxypropyl trimethoxysilane, glycidoxypropyl triethoxysilane, glycidoxypropyl methyldiethoxysilane, glycidyl butyl trimethoxysilane, and (3,4-epoxycyclohexyl)ethyl trimethoxysilane; and mercaptosilane-based alkoxy group-containing silane coupling agents such as mercaptopropyl trimethoxysilane and mercaptopropyl triethoxysilane. Commercially available examples of such silane coupling agents include "KBM403" (3-glycidoxypropyltrimethoxysilane), "KBM573" (N-phenyl-3-aminopropyltrimethoxysilane), "KBM803" (3-mercaptopropyltrimethoxysilane), and "KBE903" (3-aminopropyltriethoxysilane), all manufactured by Shin-Etsu Chemical Co., Ltd.

[0052] The alkoxy oligomer is not particularly limited as long as it is an oligomer of the above-mentioned alkoxy group-containing silane coupling agent, but from the viewpoint of being able to enjoy the effects of the present invention more effectively, epoxy group-containing alkoxysilyl resin, mercapto group-containing alkoxysilyl resin, and amino group-containing alkoxysilyl resin are preferred. These may be used alone or in combination of two or more. The alkoxy oligomer may have one or more types of functional groups.

[0053] Specific examples of such alkoxy oligomers include glycidoxyalkyl group-containing alkoxysilyl resins, aminoalkyl group-containing alkoxysilyl resins, mercaptoalkyl group-containing alkoxysilyl resins, and ureidoalkyl group-containing alkoxysilyl resins, and preferred are glycidoxyalkyl group-containing alkoxysilyl resins, aminoalkyl group-containing alkoxysilyl resins, and mercaptoalkyl group-containing alkoxysilyl resins.

[0054] The viscosity (25°C) of the alkoxy oligomer is preferably 10 mm from the viewpoint of preventing volatilization and improving handling. 2 / s or more, preferably 20 mm 2 / s or more, more preferably 30 mm 2 / s or more, 40mm 2 / s or more, or 50 mm 2 On the other hand, from the viewpoint of efficiently coating the inorganic filler, it is preferably 2000 mm 2 / s or less, preferably 1800mm 2 / s or less, 1600mm 2 / s or less, or 1500 mm 2 The viscosity (25°C) of the alkoxy oligomer can be measured using an E-type viscometer by measuring out about 0.2 mL of the alkoxy oligomer using a syringe into an apparatus adjusted to 25°C, and setting the rotation speed at 5 to 20 rpm.

[0055] The method for producing the alkoxy oligomer is not particularly limited, and it can be produced by known methods such as those described in Japanese Patent No. 3474007, and can be obtained by partially hydrolyzing the alkoxy group of a silane coupling agent (monomer) and polycondensing it. For example, the silane coupling agent and an organic solvent are placed in a reaction vessel, and the hydrolysis and condensation reaction is carried out at 20 to 80°C for 0.1 to 10 hours. In this case, a hydrochloric acid solution, a fluorine-containing compound, or the like can also be used as a catalyst.

[0056] Commercially available alkoxy oligomers may be used. Examples of commercially available alkoxy oligomers include epoxy group-containing alkoxysilyl resins ("X-41-1053" and "X-41-1059A" manufactured by Shin-Etsu Chemical Co., Ltd.), methyl group- and epoxy group-containing alkoxysilyl resins ("X-41-1056" manufactured by Shin-Etsu Chemical Co., Ltd.), primary amino group-containing alkoxysilyl resins ("X-40-2651" manufactured by Shin-Etsu Chemical Co., Ltd.), and amino groups. Examples thereof include phenyl group-containing alkoxysilyl resin ("X-40-9281" manufactured by Shin-Etsu Chemical Co., Ltd.), mercapto group-containing alkoxysilyl resin ("X-40-1805" and "X-41-1818" manufactured by Shin-Etsu Chemical Co., Ltd.), methyl group- and mercapto group-containing alkoxysilyl resin ("X-41-1810" manufactured by Shin-Etsu Chemical Co., Ltd.), and methyl group- and amino group-containing alkoxysilyl resin ("X-40-2651" manufactured by Shin-Etsu Chemical Co., Ltd.).

[0057] Therefore, in one embodiment, the resin composition R contains an inorganic filler treated with an alkoxy group-containing surface treatment agent. In a preferred embodiment, the alkoxy group-containing surface treatment agent is one or more selected from the group consisting of alkoxy group-containing silane coupling agents and oligomers thereof, and more preferably a silane coupling agent or oligomer thereof having, in addition to an alkoxy group, one or more functional groups selected from the group consisting of an amino group, an epoxy group, and a mercapto group.

[0058] 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 and being able to enjoy the effects of the present invention more effectively. 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.

[0059] 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. The amount of carbon per unit surface area of ​​the inorganic filler is preferably 0.02 mg / m 2 or more, more preferably 0.05 mg / m2 or more, more preferably 0.1 mg / m 2 More than 0.15mg / m 2 or more, or 0.2 mg / m 2 In particular, the carbon content per unit surface area of ​​the inorganic filler is 0.05 mg / m 2 In the method for producing a circuit board of the present invention, the above-mentioned concentration is preferable because it can provide an insulating layer with even smaller surface roughness. 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 preferable to use a concentration of 1 mg / m or more. 2 Less than 0.8 mg / m is preferred 2 Less than 0.5 mg / m is more preferable. 2 The following is even more preferred:

[0060] 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. An "EMIA-320V" manufactured by Horiba, Ltd., or the like can be used as the carbon analyzer. In the present invention, the carbon amount per unit surface area of ​​the inorganic filler is based on a value calculated according to the procedure described in the section "Measurement and calculation of carbon amount per unit surface area of ​​inorganic filler" below.

[0061] When the resin composition R contains an inorganic filler, the content of the inorganic filler in the resin composition (and thus the content of the inorganic filler in the resin composition layer and insulating layer) is, for example, 20% by mass or more, preferably 40% by mass or more, based on 100% by mass of the nonvolatile components in the resin composition, from the viewpoint of easily achieving an insulating layer exhibiting better dielectric properties and a lower thermal expansion coefficient. When the insulating layer contains an inorganic filler, increasing the polishing rate during chemical mechanical polishing of the insulating layer tends to increase the surface roughness of the resulting insulating layer, as the inorganic filler near the surface of the insulating layer falls off, causing depressions on the surface. In contrast, the circuit board manufacturing method of the present invention can achieve a high polishing rate and produce an insulating layer with low surface roughness, even when the inorganic filler content is higher. For example, the content of the inorganic filler in the resin composition may be increased to 50% by mass or more, 55% by mass or more, or 60% by mass or more. The upper limit of the content of the inorganic filler is not particularly limited, but may be, for example, 85% by mass or less, or 80% by mass or less.

[0062] -(d)Thermoplastic resin- The resin composition R may further contain a thermoplastic resin. Examples of the thermoplastic resin include phenoxy resin, polyvinyl acetal resin, polyolefin resin, polystyrene resin, polyimide resin, polyamideimide resin, polyetherimide resin, polysulfone resin, polyethersulfone resin, polyphenylene ether resin, polyetheretherketone resin, and polyester resin. The thermoplastic resin may be used alone or in combination of two or more.

[0063] The polystyrene-equivalent weight average molecular weight of the thermoplastic resin is preferably 8,000 or more, more preferably 10,000 or more, even more preferably 20,000 or more or 30,000 or more. The upper limit is preferably 100,000 or less, more preferably 70,000 or less, even more preferably 60,000 or less. The polystyrene-equivalent Mw of the thermoplastic resin is measured by GPC. Specifically, the polystyrene-equivalent Mw of the thermoplastic resin is measured using a Shimadzu LC-9A / RID-6A measuring apparatus, 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.

[0064] 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 "YL7800BH40," "YL7500BH30," "YX6954BH30," "YX7553," "YX7553BH30," "YL7769BH30," "YL6794," "YL7213," "YL7290," and "YL7482" manufactured by Mitsubishi Chemical Corporation.

[0065] 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 Denka 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.

[0066] The polyimide resin may be a resin having an imide structure (preferably a cyclic imide structure), such as an imide compound of an acid anhydride and a diamine compound or a diisocyanate compound. Specific examples of polyimide resins include "Rikacoat SN20" and "Rikacoat PN20" manufactured by New Japan Chemical Co., Ltd. Specific examples of polyimide resins include linear polyimides obtained by reacting bifunctional hydroxyl-terminated polybutadiene, a diisocyanate compound, and a tetrabasic acid anhydride (polyimides described in JP 2006-37083 A), and modified polyimides such as polysiloxane skeleton-containing polyimides (polyimides described in JP 2002-12667 A and JP 2000-319386 A).

[0067] 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 Resonac Corporation.

[0068] 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.

[0069] Specific examples of polysulfone resins include polysulfones "P1700" and "P3500" manufactured by Solvay Advanced Polymers.

[0070] 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.

[0071] Examples of polystyrene resins include homopolymers of styrene, copolymers of styrene and diene compounds (butadiene, isoprene, etc.), and hydrogenated products thereof.

[0072] 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.

[0073] When the resin composition R contains a thermoplastic resin, the content of the 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 resin components in the resin composition. The upper limit is preferably 20% by mass or less, more preferably 15% by mass or less, and even more preferably 10% by mass or less.

[0074] -(e) Curing accelerator- The resin composition R may further contain a curing accelerator. Examples of the curing accelerator include amine-based curing accelerators, imidazole-based curing accelerators, guanidine-based curing accelerators, metal-based curing accelerators, and peroxide-based curing accelerators. The curing accelerators may be used alone or in combination of two or more.

[0075] When the resin composition R contains a curing accelerator, the content of the curing accelerator in the resin composition may be determined depending on the properties required of the resin composition, but when the resin component in the resin composition is taken as 100% by mass, it is preferably 5% by mass or less, more preferably 4% by mass or less, and even more preferably 3% by mass or less, and the lower limit may be 0.01% by mass or more, 0.05% by mass or more, 0.1% by mass or more, etc.

[0076] The resin composition R may further contain other additives. Examples of such additives include organic fillers such as rubber particles; photocationic polymerization initiators and photoacid generators, such as sulfonium salts, iodonium salts, and nonionic initiators; photosensitizers such as naphthoquinone diazide compounds; radical polymerization initiators, such as peroxide radical polymerization initiators and azo radical polymerization initiators; organometallic compounds, such as organocopper compounds, organozinc compounds, and organocobalt compounds; colorants, such as phthalocyanine blue, phthalocyanine green, iodine green, diazo yellow, crystal violet, titanium oxide, and carbon black; polymerization inhibitors, such as hydroquinone, catechol, pyrogallol, and phenothiazine; leveling agents, such as silicone leveling agents and acrylic polymer leveling agents; thickeners, such as bentone and montmorillonite; antifoaming agents, such as silicone antifoaming agents, acrylic antifoaming agents, fluorine-based antifoaming agents, and vinyl resin antifoaming agents; and ultraviolet absorbers, such as benzotriazole ultraviolet absorbers. adhesion promoters such as triazole-based adhesion promoters, tetrazole-based adhesion promoters, and triazine-based adhesion promoters; antioxidants such as hindered phenol-based antioxidants; fluorescent brighteners such as stilbene derivatives; surfactants such as fluorine-based surfactants and silicone-based surfactants; flame retardants such as phosphorus-based flame retardants (e.g., phosphate ester compounds, phosphazene compounds, phosphinic acid compounds, and red phosphorus), nitrogen-based flame retardants (e.g., melamine sulfate), halogen-based flame retardants, and inorganic flame retardants (e.g., antimony trioxide); dispersants such as phosphate ester-based dispersants, polyoxyalkylene-based dispersants, acetylene-based dispersants, silicone-based dispersants, anionic dispersants, and cationic dispersants; and stabilizers such as borate-based stabilizers, titanate-based stabilizers, aluminate-based stabilizers, zirconate-based stabilizers, isocyanate-based stabilizers, carboxylic acid-based stabilizers, and carboxylic acid anhydride-based stabilizers. The content of such additives may be determined depending on the properties required for the resin composition.

[0077] The method for preparing the resin composition R 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.

[0078] From the viewpoint of being able to provide an insulating layer that exhibits good mechanical properties and heat resistance and is highly reliable, the glass transition temperature of the cured product obtained by curing Resin Composition R at 200°C for 120 minutes, i.e., Tg2 described below, is preferably 140°C or higher, more preferably 145°C or higher or 150°C or higher. There are no particular limitations on the upper limit of Tg2, but it can usually be set to 250°C or lower, 240°C or lower, or the like.

[0079] The present invention will be described in detail below with reference to preferred embodiments thereof. The present invention is not limited to the following description, and each component can be appropriately modified within the scope of the present invention.

[0080] [Circuit board manufacturing method] The method for producing a circuit board of the present invention (hereinafter also simply referred to as the "method of the present invention") includes the following steps (X), (Y) and (Z). (X) A step of forming a resin composition layer from the resin composition R on a substrate having conductive pillars for interlayer connection on its surface so as to embed the conductive pillars, and curing the resin composition layer to form an insulating layer. (Y) A process of polishing the insulating layer by chemical mechanical polishing (CMP) to expose the conductor pillars (Z) A process for forming a plating seed layer on the surface of the insulating layer Furthermore, the method for producing a circuit board of the present invention is characterized in that, when the glass transition temperature (°C) of the cured product obtained by curing resin composition R under the curing conditions in step (X) is Tg1, and the glass transition temperature (°C) of the cured product obtained by curing resin composition R at 200°C for 120 minutes is Tg2, step (X) is carried out so that 0.5≦Tg1 / Tg2≦0.9 is satisfied.

[0081] As mentioned above, as electronic devices become more powerful, circuit boards used in semiconductor packages are required to have finer wiring, and there are high hopes for a technology for manufacturing circuit boards that uses chemical mechanical polishing (CMP) to polish an insulating layer and then form a conductor layer on the resulting polished surface of the insulating layer. This is because the surface of the insulating layer after CMP is flat and smooth, which is thought to contribute to the finer conductor layer formed on it.

[0082] On the other hand, in order to increase the productivity of semiconductor packages, efforts are being made to speed up each production process, and this has led to a demand for faster chemical mechanical polishing of insulating layers. Increasing the polishing speed during chemical mechanical polishing of insulating layers by adjusting the polishing conditions (rotation speed, pressure, type and concentration of abrasive) increases the surface roughness of the resulting insulating layer, thereby negating the benefits of chemical mechanical polishing. Furthermore, insulating layers used in circuit boards often contain inorganic fillers such as silica to achieve properties such as a low thermal expansion coefficient and a low dielectric loss tangent. In such cases, the above-mentioned problems have been found to be more pronounced. Specifically, we have found that increasing the polishing speed during chemical mechanical polishing of insulating layers containing inorganic fillers increases the surface roughness of the resulting insulating layer, due to the inorganic filler being removed from the surface of the insulating layer and causing depressions on the surface.

[0083] In contrast, the method of the present invention, in which step (X) is carried out so that 0.5≦Tg1 / Tg2≦0.9 is satisfied, can achieve a high polishing rate when chemically mechanically polishing an insulating layer and can also produce an insulating layer with small surface roughness. Therefore, the present invention significantly contributes to the finer wiring of circuit boards and to improving the productivity of circuit boards with fine wiring.

[0084] <Process (X)> In step (X), a resin composition layer is formed from resin composition R on a substrate having conductive pillars for interlayer connection on its surface so as to embed the conductive pillars, and the resin composition layer is cured to form an insulating layer.

[0085] - Substrate with conductive pillars on the surface for interlayer connection - As the substrate having conductive pillars for interlayer connection provided on its surface used in step (X), any substrate used in the manufacture of circuit boards may be used as long as conductive pillars for interlayer connection are provided on its surface.

[0086] Examples of the base substrate include substrates that are commonly used as core materials in the manufacture of circuit boards, such as glass epoxy substrates, polyester substrates, polyimide substrates, BT resin substrates, and thermosetting polyphenylene ether substrates. The substrate may have a conductor layer on one or both sides, and this conductor layer may be patterned.

[0087] The base substrate may be any substrate selected from a metal substrate, an inorganic substrate, and an organic substrate, and may be a substrate with a metal layer provided on the surface of such a substrate to function as a plating seed layer when forming conductor pillars.

[0088] For the metal substrate, examples of its constituent material (metal material) include copper, aluminum, and alloys of these with other metals (for example, tin, chromium, silver, magnesium, nickel, zirconium, silicon, titanium, etc.). Examples of inorganic substrates include glass substrates, ceramic substrates, and semiconductor wafers, while examples of organic substrates include substrates made of plastic materials. The material of the glass substrate is not particularly limited, and various glass materials such as borosilicate glass, quartz glass, lead glass, and soda-lime glass may be used. The material of the ceramic substrate is not particularly limited, and various ceramic materials such as alumina and zirconia may be used. Examples of semiconductor wafers include, but are not limited to, silicon (Si)-based wafers. Examples of wafers that may be used include gallium arsenide (GaAs), indium phosphide (InP), gallium phosphide (GaP), gallium nitride (GaN), gallium tellurium (GaTe), zinc selenium (ZnSe), and silicon carbide (SiC) wafers. Examples of plastic materials include polyesters such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), acrylics such as polycarbonate (PC) and polymethyl methacrylate (PMMA), cyclic polyolefins, triacetyl cellulose (TAC), polyether sulfide (PES), polyether ketone, polyimide, etc. Composite materials such as fiber-reinforced plastics may also be used.

[0089] When using a substrate with a metal layer provided on the surface of such a substrate, the metal material constituting the metal layer is not particularly limited as long as it can form a conductor layer on the surface of the metal layer, and examples thereof include copper, palladium, gold, platinum, silver, aluminum, and alloys of these with other metals (e.g., tin, chromium, magnesium, nickel, zirconium, silicon, titanium, etc.) The metal layer can be formed on the substrate by, for example, sputtering, electroless plating, or attaching an ultrathin metal foil.

[0090] As described above, the substrate has conductive pillars for interlayer connection on its surface. The substrate may also have other conductive circuits on its surface in addition to the conductive pillars for interlayer connection.

[0091] The conductor material used for the conductor circuits, including the conductor pillars, is not particularly limited. In a preferred embodiment, the conductor circuit 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 circuit may be made of a single metal or an alloy. Examples of the alloy include 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 conductor circuit formation, cost, and the like, single metals such as chromium, nickel, titanium, aluminum, zinc, gold, palladium, silver, or copper, or alloys such as nickel-chromium alloys, copper-nickel alloys, and copper-titanium alloys are preferred. Single metals such as chromium, nickel, titanium, aluminum, zinc, gold, palladium, silver, or copper, or alloys such as nickel-chromium alloys, copper-nickel alloys, and copper-titanium alloys are more preferred, and single metal copper is even more preferred.

[0092] Conductor circuits, including conductor pillars, may have a single-layer structure or a multi-layer structure in which two or more single-metal or alloy layers made of different types of metals or alloys are stacked. When the conductor circuit has a multi-layer structure, the layer in contact with the insulating layer is preferably a single-metal layer of chromium, zinc, or titanium, or an alloy layer of a nickel-chromium alloy.

[0093] Conductor circuits including these conductor pillars for interlayer connection can be provided on the surface of the substrate using known methods. An example of a method for forming conductor circuits including conductor pillars for interlayer connection on the surface of the substrate will be described below.

[0094] The formation of a conductor circuit on the surface of the substrate may be carried out in accordance with a known circuit formation method such as a semi-additive method or a full-additive method.

[0095] In one embodiment, the circuit formation method comprises: (A-1) forming a plating seed layer on the surface of a substrate, providing a photoresist on the plating seed layer, and exposing and developing the photoresist to expose the plating seed layer in a manner corresponding to the circuit pattern of the conductor circuit to be formed; (A-2) Forming a conductor layer on the exposed plating seed layer to form a conductor circuit Includes.

[0096] In the above (A-1), the plating seed layer may be formed in the same manner as in step (Z) described below. When a substrate with a metal layer is used as the substrate, the metal layer can be used as the plating seed layer, and therefore the above (A-1) can be read as "providing a photoresist on the metal layer of the substrate with a metal layer, exposing and developing the photoresist, and exposing the plating seed layer in accordance with the circuit pattern of the conductor circuit to be formed," and the above (A-2) can be read as "forming a conductor layer on the exposed metal layer, and forming the conductor circuit."

[0097] As the photoresist, a conventionally known photoresist that can be developed into a desired conductor circuit pattern may be used, and either a film-type photoresist (dry film photoresist) or a liquid photoresist may be used.

[0098] In particular, from the viewpoint of being able to form a conductor circuit in a fine pattern, it is preferable to form the conductor circuit in accordance with a semi-additive method. Therefore, in the above (A-2), it is preferable to form the conductor layer on the exposed plating seed layer by an electrolytic plating method.

[0099] The formation of a conductor layer via a photoresist may be carried out multiple times to form a desired circuit pattern or interlayer connection pattern. For example, a conductor circuit is formed by carrying out the above steps (A-1) and (A-2) using a first photoresist. Then, a second photoresist is provided on the substrate on which the conductor circuit is provided, and the photoresist is exposed and developed to expose the conductor layer corresponding to the interlayer connection pattern. Next, a further conductor layer is provided on the exposed conductor circuit, and conductor pillars for interlayer connection can be formed. After the conductor pillars for interlayer connection are formed, the second photoresist can be removed.

[0100] When a substrate that functions as a component of a circuit board, such as a core material, is used as the substrate, a conductor circuit, including conductor pillars for interlayer connection, is formed, and then the plating seed layer in the circuit-unformed portion is removed. This results in a substrate having conductor pillars for interlayer connection provided on its surface. Alternatively, when a dummy substrate that is removed in a later step, such as when a substrate with a metal layer is used as the substrate, removal of the plating seed layer in the circuit-unformed portion is not necessary. When a dummy substrate is used as the substrate, the dummy substrate can be removed in a later step in the manufacture of the circuit board to expose the conductor circuits, including the conductor pillars.

[0101] The dimensions of the conductor circuit, including the conductor pillar for interlayer connection, may be determined according to the intended design of the circuit board. For example, the height of the conductor pillar for interlayer connection (the dimension of the conductor pillar in the thickness direction of the circuit board) may be, for example, 30 μm or less, 25 μm or less, 20 μm or less, 15 μm or less, or 10 μm or less, from the viewpoint of thinning the circuit board. The lower limit is not particularly limited, but may typically be 1 μm or more, 2 μm or more, or 3 μm or more. Furthermore, the minimum line / space ratio (L / S) of the conductor circuit may be, for example, 5 / 5 μm or less, 3 / 3 μm or less, 2 / 2 μm or less, 1.5 / 1.5 μm or less, or 1 / 1 μm or less, from the viewpoint of fine wiring.

[0102] -Resin composition layer- A resin composition layer is formed from the resin composition R so as to embed the conductor pillars. The resin composition R is as explained above in the section <Resin composition>.

[0103] Step (X) may be carried out by applying the above-mentioned resin composition R in a varnish state, or by forming a resin composition layer containing the resin composition R in advance and laminating the resin composition layer.

[0104] In a preferred embodiment, step (X) includes laminating a resin sheet including a support and a resin composition layer provided on the support onto a substrate so that the resin composition layer is bonded to the conductor pillar.

[0105] 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. When a film made of a plastic material is used as the support film, examples of the plastic material include polyesters such as PET and PEN, acrylics such as PC and PMMA, cyclic polyolefins, TAC, PES, polyether ketone, and polyimides. 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. As the copper foil, foil made of a single metal such as copper may be used, or foil made of an alloy of copper and another metal (e.g., tin, chromium, silver, magnesium, nickel, zirconium, silicon, titanium, etc.) may be used. The surface of the support that will be bonded to the resin composition layer may be subjected to a matte treatment, corona treatment, or antistatic treatment. Alternatively, a support with a release layer, which has a release layer on the surface that will be bonded to the resin composition layer, may be used. The release agent used in the release layer of the support with a release layer may be, for example, one or more release agents selected from the group consisting of alkyd resins, olefin resins, urethane resins, and silicone resins. Commercially available release agents include, for example, alkyd resin-based release agents such as "SK-1," "AL-5," and "AL-7" manufactured by Lintec Corporation.

[0106] 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 the support is a support with a release layer, it is preferable that the thickness of the entire support with a release layer is in the above range.

[0107] The resin sheet can be prepared, for example, by preparing a resin varnish by dissolving the above-mentioned resin composition R in an organic solvent, applying the resin varnish to a support film using a die coater or the like, and then drying the applied resin varnish to form a resin composition layer.

[0108] In the resin sheet, the thickness of the resin composition layer is not particularly limited as long as it allows the conductor pillars for interlayer connection to be embedded, and may be appropriately determined depending on the specific design. From the viewpoint of thinning the circuit board and the productivity of the circuit board, the thickness may be, for example, 40 μm or less, 30 μm or less, 25 μm or less, 20 μm or less, 15 μm or less, 10 μm or less, etc. The lower limit is not particularly limited, but it may usually be 1 μm or more, 2 μm or more, 3 μm or more, etc.

[0109] 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 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 to 40 μm. By laminating the protective film, it is possible to prevent adhesion of dust and scratches to the surface of the resin composition layer. When the resin sheet has a protective film, it can be used by peeling off the protective film.

[0110] The lamination of the resin sheet is not particularly limited as long as the resin composition layer can be laminated so as to embed the conductive pillars, and can be performed, for example, by thermocompression bonding the resin sheet to the substrate from the support side. Examples of a member for thermocompression bonding the resin sheet to the substrate (hereinafter also referred to as a "thermocompression bonding member") include a heated metal plate (such as a SUS panel) or a metal roll (SUS roll). Note that rather than pressing the thermocompression bonding member directly onto the resin sheet, it is preferable to press it via an elastic material such as heat-resistant rubber so that the resin sheet can sufficiently conform to the surface irregularities of the substrate based on the conductive circuits, including the conductive pillars.

[0111] Lamination of the resin sheets may be performed 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 performed under reduced pressure conditions of 26.7 hPa or less. The lamination may be performed using a vacuum laminator. Examples of commercially available vacuum laminators include a vacuum pressure laminator manufactured by Meiki Seisakusho Co., Ltd., a vacuum applicator manufactured by Nikko Materials Co., Ltd., and a batch-type vacuum pressure laminator.

[0112] After lamination, the laminated resin sheets may be smoothed under normal pressure (atmospheric pressure), for example, by pressing the support side with a thermocompression member. The pressing conditions for the smoothing treatment may be the same as the thermocompression conditions for lamination. Lamination and smoothing treatment may be performed consecutively using a vacuum laminator.

[0113] -Curing of resin composition layer (forming insulating layer)- The resin composition layer is cured to form an insulating layer, which is formed so as to embed the conductor pillars and other conductor circuits.

[0114] From the viewpoint of achieving a high removal rate and providing an insulating layer with small surface roughness, it is necessary to carry out step (X) so that the relationship 0.5≦Tg1 / Tg2≦0.9 is satisfied, where Tg1 is the glass transition temperature (°C) of the cured product obtained by curing resin composition R under the curing conditions in step (X) and Tg2 is the glass transition temperature (°C) of the cured product obtained by curing resin composition R at 200°C for 120 minutes.

[0115] From the viewpoint of achieving a higher polishing rate and obtaining an insulating layer with smaller surface roughness, it is suitable to carry out step (X) so that the Tg1 / Tg2 ratio is preferably 0.55 or more, more preferably 0.6 or more, even more preferably 0.62 or more or 0.64 or more, and the upper limit thereof is preferably 0.85 or less, more preferably 0.8 or less.

[0116] In the present invention, the glass transition temperatures Tg1 and Tg2 of Resin Composition R are based on the value determined by measuring a cured product of Resin Composition R using a dynamic mechanical analyzer (DMA) at a temperature rise rate of 2°C / min in the range of 25°C to 240°C, as described below in the section <Measurement of Glass Transition Temperature of Resin Composition>, and rounding off the temperature (°C) at which the loss tangent (tanδ), calculated as the ratio of the storage modulus (E') to the loss modulus (E"), reaches its maximum value.

[0117] The curing conditions in step (X) can be determined so that the Tg1 / Tg2 ratio falls within the range of the present invention, and will vary depending on factors such as the composition of resin composition R. For example, the curing temperature may be determined preferably in the range of 100°C to 220°C, more preferably in the range of 120°C to 200°C, and the curing time may be determined preferably in the range of 5 minutes to 240 minutes, more preferably in the range of 10 minutes to 150 minutes.

[0118] The curing of the resin composition layer in step (X) may be carried out in a single heat treatment, or in two or more heat treatments. When two or more heat treatments are used, the temperature in the first heat treatment is preferably lower than the temperatures in the second and subsequent heat treatments.

[0119] When a resin sheet is used to form a resin composition layer (insulating layer), the support may be removed before or after curing the resin composition layer. From the viewpoint of achieving a higher polishing rate and providing an insulating layer with a smaller surface roughness, it is preferable to remove the support after curing the resin composition layer.

[0120] <Process (Y)> In step (Y), the insulating layer is polished by chemical mechanical polishing (CMP) to expose the conductor pillars.

[0121] In chemical mechanical polishing (CMP), an abrasive slurry is used to polish the surface of the insulating layer.

[0122] The abrasive (abrasive grains) contained as dispersoid in the polishing slurry may be any conventionally known abrasive as long as it can polish the insulating layer, which is a cured product of the resin composition R. Examples of abrasive materials include inorganic particles such as silica, alumina, cerium oxide, titanium oxide, and chromium oxide, and organic particles such as diamond and hard resin particles. The abrasive may be used alone or in combination of two or more.

[0123] The average particle size of the abrasive is preferably small from the viewpoint of easily obtaining an insulating layer with small surface roughness, and when the resin composition R contains an inorganic filler, it is preferable to use an abrasive having an average particle size smaller than the average particle size of the inorganic filler. The average particle size of the abrasive can be, for example, 1 μm or less, 0.5 μm or less, 0.4 μm or less, 0.2 μm or less, etc., and the lower limit of the average particle size is not particularly limited, but can usually be 0.005 μm or more, 0.01 μm or more, etc.

[0124] The concentration of the abrasive in the polishing slurry is not particularly limited, and may be determined, for example, in the range of 0.01 to 30% by mass (preferably 0.1 to 25% by mass).

[0125] In view of the dispersibility of the abrasive, the polishing slurry may also contain a dispersant.As the dispersant, any dispersant that is conventionally known and used in the polishing slurry of chemical mechanical polishing may be used.As such a dispersant, for example, various surfactants such as ionic surfactants, nonionic surfactants, and acids such as hydrochloric acid and nitric acid may be listed.In view of achieving good dispersibility of the abrasive, the concentration of the dispersant in the polishing slurry may be appropriately determined in relation to the concentration of the abrasive.

[0126] The polishing slurry may further contain other components as long as they do not inhibit the effect of the present invention, and such other components may include, for example, pH adjuster, thickener, oxidizer, corrosion inhibitor, etc. The concentration of these other components in the polishing slurry may be appropriately determined according to the intended purpose.

[0127] Water may be used as the dispersion medium of the polishing slurry.

[0128] The polishing rate of the insulating layer can be adjusted by selecting and changing the hardness and average particle size of the abrasive and the concentration of the abrasive in the polishing slurry. For example, the higher the hardness of the abrasive, the larger the average particle size of the abrasive, and the higher the concentration of the abrasive in the polishing slurry, the higher the polishing rate of the insulating layer tends to be.

[0129] In chemical mechanical polishing (CMP), the pressure during polishing (pressure between the carrier holding the substrate and the polishing pad) may be appropriately determined to achieve a desired polishing rate depending on the composition of the insulating layer, etc. The rotation speed of the carrier holding the substrate and the rotation speed of the polishing platen holding the polishing pad may also be appropriately determined to achieve a desired polishing rate depending on the composition of the insulating layer, etc. The higher the pressure during polishing and the higher the rotation speed of the carrier and polishing platen, the higher the polishing rate of the insulating layer tends to be.

[0130] As mentioned above, in order to further advance the finer wiring of circuit boards, a technology for manufacturing circuit boards by polishing an insulating layer using chemical mechanical polishing (CMP) and then forming a conductor layer on the resulting polished surface of the insulating layer is expected. This is because the surface of the insulating layer after chemical mechanical polishing is flat and smooth, which is thought to contribute to the finer conductor layer formed on it. However, when chemically mechanically polishing an insulating layer, if the polishing conditions (rotation speed, pressure, type and concentration of abrasive) are adjusted to increase the polishing rate, the surface roughness of the resulting insulating layer increases, thereby negating the advantages of employing chemical mechanical polishing. It has been found that this problem becomes more pronounced, particularly when the insulating layer contains an inorganic filler.

[0131] In contrast, the method of the present invention, in which step (X) is carried out so that 0.5≦Tg1 / Tg2≦0.9 is satisfied, can provide an insulating layer with low surface roughness while achieving a high polishing rate. The polishing rate for the insulating layer in step (Y) can be, for example, 1 μm / min or more, and can even be increased to 1.2 μm / min or more, 1.4 μm / min or more, 1.5 μm / min or more, or 1.6 μm / min or more.

[0132] In step (Y), the polishing amount (thickness) of the insulating layer is determined depending on the difference between the height of the conductive pillar and the thickness of the insulating layer, and is preferably 1 μm or more, more preferably 2 μm or more or 3 μm or more, from the viewpoint of obtaining a flat insulating layer with low surface roughness. The upper limit of the polishing amount varies depending on the polishing thickness required to expose the conductive pillar, but from the viewpoint of shortening the time required for step (Y) and thereby increasing the productivity of the circuit board, it can be preferably 20 μm or less, 15 μm or less, 10 μm or less, etc.

[0133] As described above, according to the method of the present invention, an insulating layer with low surface roughness can be formed by chemical mechanical polishing. In one embodiment, the arithmetic mean roughness Ra of the surface (polished surface) of the insulating layer obtained in step (Y) is preferably 70 nm or less, more preferably 50 nm or less, and even more preferably 40 nm or less, 35 nm or less, or 30 nm or less. The lower limit of the arithmetic mean roughness Ra is not particularly limited and may be, for example, 1 nm or more, 2 nm or more, or 3 nm or more.

[0134] The chemical mechanical polishing of the insulating layer may be carried out using a commercially available chemical mechanical polishing apparatus, such as the polishing apparatus "LaboForce-100" manufactured by Struers.

[0135] <Process (Z)> In the step (Z), a plating seed layer is formed on the surface of the insulating layer.

[0136] The thickness of the plating seed layer may be preferably 500 nm or less, more preferably 400 nm or less, and even more preferably 300 nm or less. After a conductor layer is formed on the plating seed layer in a desired pattern, unnecessary portions of the plating seed layer other than the conductor layer formation portion are removed by etching or the like. In this case, the thinner the plating seed layer is, the easier it is to remove the unnecessary portions of the plating seed layer, and the smaller the thickness of the plating seed layer is, the more easily erosion of the conductor pattern can be minimized when removing the unnecessary portions, which is advantageous for realizing fine wiring.

[0137] In this regard, when a thin plating seed layer is formed on the surface of an insulating layer, the thickness of the conductor layer formed on the plating seed layer by electroplating tends to vary, resulting in a phenomenon known as plating burn. This is thought to be due to the unevenness of the plating seed layer caused by the unevenness of the insulating layer surface. Specifically, the electrical resistance of the thin plating seed layer is higher than that of the thick plating seed layer. When a conductor layer is formed on the thin plating seed layer by electroplating, the plating growth is delayed in the thin plating seed layer and the high electrical resistance compared to other parts, resulting in insufficient formation of the conductor layer, making it difficult to form a uniform conductor layer.

[0138] In contrast, according to the method of the present invention, as described above, an insulating layer with a small surface roughness can be formed by chemical mechanical polishing, and plating burn can be suppressed even if the thickness of the plating seed layer is made thinner. For example, the thickness of the plating seed layer may be reduced to 280 nm or less, 260 nm or less, or 250 nm or less.

[0139] The plating seed layer includes at least a conductive seed layer. The conductive seed layer functions as an electrode in an electrolytic plating method. The conductive material constituting the conductive seed layer is not particularly limited as long as it exhibits sufficient conductivity, and suitable examples include copper, palladium, gold, platinum, silver, aluminum, and alloys thereof. The plating seed layer may also include a diffusion barrier layer. The diffusion barrier layer is a layer that prevents the conductive material constituting the conductive seed layer from diffusing into the insulating layer and causing dielectric breakdown. The material constituting the diffusion barrier layer is not particularly limited as long as it can suppress or prevent the diffusion of the conductive material constituting the conductive seed layer, and suitable examples include titanium, tungsten, tantalum, and alloys thereof. When the plating seed layer includes a diffusion barrier layer, the "thickness of the plating seed layer" in this specification refers to the average thickness of the entire plating seed layer, including not only the conductive seed layer but also the diffusion barrier layer.

[0140] When the plating seed layer includes a diffusion barrier layer, the thickness of the diffusion barrier layer is not particularly limited as long as it can suppress or prevent diffusion of the conductive material constituting the conductive seed layer, but from the viewpoint of contributing to fine wiring, it is preferably 50 nm or less, more preferably 40 nm or less, and even more preferably 30 nm or less. The lower limit of the thickness of the diffusion barrier layer is not particularly limited and may be, for example, 1 nm or more, 3 nm or more, 5 nm or more, etc. In this case, the remainder of the plating seed layer is preferably a conductive seed layer, and the thickness of the conductive seed layer may be determined in relation to the thickness of the diffusion barrier layer so that the thickness of the entire plating seed layer falls within the above-mentioned preferred range.

[0141] The plating seed layer may be formed by dry plating or wet plating. Examples of dry plating include physical vapor deposition (PVD) methods such as sputtering, ion plating, and vacuum deposition, and chemical vapor deposition (CVD) methods such as thermal CVD and plasma CVD. Examples of wet plating include electroless plating. Sputtering and electroless plating are preferred from the viewpoint of easily forming a thin plating seed layer with a more uniform thickness, and sputtering is particularly preferred from the viewpoint of realizing fine wiring with excellent adhesion strength. Therefore, in a preferred embodiment, the plating seed layer is formed by sputtering in step (Z).

[0142] After step (Z), a conductor layer can be formed on the plating seed layer by electroplating. Thus, in one embodiment, the method of the present invention includes the step of forming a conductor layer on the plating seed layer by electroplating.

[0143] The conductive material used for the conductive layer is not particularly limited, and suitable examples are as explained for the conductive circuit including the conductive pillar in relation to the step (X).

[0144] The conductor layer may be formed by a so-called semi-additive method. That is, a photoresist (plating resist) is formed on the plating seed layer formed in step (Z), exposing a portion of the plating seed layer corresponding to the desired wiring pattern. Next, a conductor layer is formed on the exposed plating seed layer by electrolytic plating, and the photoresist is then removed. Here, as described above in relation to step (X), the formation of the conductor layer via the photoresist may be performed multiple times to form a desired circuit pattern or interlayer connection pattern (such as a conductor pillar). Thereafter, unnecessary plating seed layer other than the conductor layer formation portion is removed by etching or the like, thereby forming a conductor layer (conductor circuit) having the desired wiring pattern.

[0145] According to the method of the present invention, it is possible to form a conductor circuit with an L / S of, for example, 5 / 5 μm or less, 4 / 4 μm or less, 3 / 3 μm or less, 2 / 2 μm or less, 1.5 / 1.5 μm or less, or 1 / 1 μm or less while suppressing plating burn.

[0146] A multilayer circuit board may be manufactured by further forming an insulating layer, chemically and mechanically polishing the insulating layer, and forming a conductor circuit. In manufacturing the circuit board, the insulating layer may be subjected to an additional heat treatment (post-curing) after chemically and mechanically polishing. The additional heat treatment may be carried out under conditions that are appropriately determined depending on the composition of the resin composition R, etc., so as to achieve complete curing of the curable resin. The additional heat treatment may be carried out each time a conductor circuit is formed, or may be carried out collectively on multiple insulating layers after multiple layers of conductor circuits have been formed.

[0147] Furthermore, when a dummy substrate such as a substrate with a metal layer is used as the substrate in step (X), depending on the type of metal layer and substrate used, the metal layer and substrate may be removed simultaneously, or the substrate may be removed first and then the metal layer may be removed, thereby exposing the insulating layer formed in step (X) and obtaining a circuit board in which conductor circuits including conductor pillars are exposed.

[0148] As described above, the circuit board manufactured by the method of the present invention can be suitably used as a circuit board for a semiconductor package (circuit board for a semiconductor package). The semiconductor package using the circuit board manufactured by the method of the present invention may be either a fan-in package or a fan-out package. The fan-out package is advantageous because it allows for the formation of a large-area conductor circuit with a fine pattern, in addition to the inherent feature of the fan-out package, namely, the ability to form a large-area rewiring layer. Therefore, in a preferred embodiment, the circuit board manufactured by the method of the present invention is a circuit board for a fan-out package. The circuit board manufactured by the method of the present invention can be widely used as a circuit board for constituting a semiconductor package, and may be, for example, an interposer for a multi-chip package. For example, an interposer may be manufactured alone using a dummy substrate such as a substrate with a metal layer as the substrate, or an interposer / core circuit board configuration may be manufactured using a core circuit board for a semiconductor package as the substrate.

[0149] In manufacturing a semiconductor package, one main surface of a circuit board is electrically connected to a semiconductor chip, and board connection terminals such as bumps may be formed on the other main surface of the circuit board for mounting on a printed wiring board, or the other main surface of the circuit board may be electrically connected to a core circuit board for the semiconductor package, and then board connection terminals such as bumps may be formed on the main surface of the core circuit board on the board connection side for mounting on a printed wiring board. [Example]

[0150] The present invention will be described in more detail below with reference to examples. The present invention is not limited to these examples. In the following, "parts" and "%" representing amounts mean "parts by mass" and "% by mass", respectively, unless otherwise specified. Unless otherwise specified, the temperature and pressure conditions are room temperature (25°C) and atmospheric pressure (1 atm).

[0151] <Inorganic filler used> The inorganic fillers used in the examples and comparative examples will be described below.

[0152] -Inorganic filler 1- 100 parts by mass of spherical silica ("SO-C2" manufactured by Admatechs Co., Ltd., average particle size 0.5 μm) was placed in a Henschel-type mixer, and the spherical silica was stirred for 10 minutes while spraying 0.6 parts by mass of an alkoxy group-containing silane coupling agent ("KBM573" manufactured by Shin-Etsu Chemical Co., Ltd., N-phenyl-3-aminopropyltrimethoxysilane), and then stirred for an additional 1 hour at 75°C. After that, the volatile components were distilled off, and inorganic filler 1 (carbon content per unit surface area 0.24 mg / m) was obtained. 2 ) was produced.

[0153] -Inorganic filler 2- 100 parts by mass of spherical silica ("SO-C2" manufactured by Admatechs Co., Ltd., average particle size 0.5 μm) was placed in a Henschel-type mixer, and the alkoxy groups of an oligomer of an alkoxy group-containing silane coupling agent ("KBM573" (N-phenyl-3-aminopropyltrimethoxysilane) manufactured by Shin-Etsu Chemical Co., Ltd.) were partially hydrolyzed and polycondensed (dehydration condensation) to give an oligomer with a viscosity of 1045 mm. 2 The spherical silica was stirred for 10 minutes while spraying 0.6 parts by mass of 0.6 parts by mass of 0.6% ... 2 ) was produced.

[0154] -Inorganic filler 3- 100 parts by mass of spherical silica ("SO-C2" manufactured by Admatechs Co., Ltd., average particle size 0.5 μm) was placed in a Henschel-type mixer, and the spherical silica was stirred for 10 minutes while spraying 0.6 parts by mass of an alkoxy group-containing silane coupling agent ("KBM403" manufactured by Shin-Etsu Chemical Co., Ltd., 3-glycidoxypropyltrimethoxysilane), and then stirred for an additional 1 hour at 75°C. After that, the volatile components were distilled off, and inorganic filler 3 (carbon content per unit surface area: 0.22 mg / m) was obtained. 2 ) was produced.

[0155] -Inorganic filler 4- 100 parts by mass of spherical silica ("SO-C2" manufactured by Admatechs Co., Ltd., average particle size 0.5 μm) was charged into a Henschel-type mixer, and an oligomer-type alkoxy group-containing silane coupling agent ("X-41-1056" manufactured by Shin-Etsu Chemical Co., Ltd., glycidoxypropyl group-containing methoxysilyl resin, viscosity 40 mm) was mixed. 2 The spherical silica was stirred for 10 minutes while spraying 0.6 parts by mass of 0.6 parts by mass of 0.60 mg / m² / s, and then further stirred at 75°C for 1 hour. After that, the volatile components were distilled off, and inorganic filler 4 (amount of carbon per unit surface area: 0.30 mg / m²) was obtained. 2 ) was produced.

[0156] <Measurement and calculation of carbon amount per unit surface area of ​​inorganic filler> The amount of carbon per unit surface area of ​​the prepared inorganic filler was measured and calculated by the following procedure. That is, 3 g of each prepared inorganic filler was used as a sample. The sample and 30 g of MEK (methyl ethyl ketone) were placed in a centrifuge tube, stirred to suspend the solids, and irradiated with 500 W ultrasonic waves for 5 minutes. Subsequently, solid-liquid separation was performed by centrifugation, and the supernatant was removed. Furthermore, 30 g of MEK was added, stirred to suspend the solids, and irradiated with 500 W ultrasonic waves for 5 minutes. Subsequently, solid-liquid separation was performed by centrifugation, and the supernatant was removed. The solids were dried at 150 °C for 30 minutes. 0.3 g of this dried sample was accurately weighed into a measurement crucible, and combustion improver (3.0 g of tungsten and 0.3 g of tin) was also placed in the measurement crucible. The measurement crucible was set in a carbon analyzer ("EMIA-320V" manufactured by Horiba, Ltd.) to measure the carbon content. The measured carbon amount was divided by the specific surface area of ​​the inorganic filler used to calculate the carbon amount per unit surface area.

[0157] <Preparation Example 1> (Preparation of Resin Composition 1) Eight parts of a naphthalene-type epoxy resin (epoxy equivalent weight 144, DIC Corporation "EXA4032SS"), 11 parts of a bixylenol-type epoxy resin (epoxy equivalent weight 190, Mitsubishi Chemical Corporation "YX4000HK"), and 9 parts of a naphthalene-type epoxy resin (epoxy equivalent weight approximately 330, Nippon Steel Chemical & Material Co., Ltd. "ESN475V") were dissolved in 32 parts of solvent naphtha with stirring, and then cooled to room temperature. 1.5 parts of rubber particles (Aica Kogyo Co., Ltd. "Staphyloid AC3816N") were added to 6 parts of solvent naphtha and allowed to swell at 20°C for 12 hours. 100.6 parts of inorganic filler 1 were then mixed and uniformly dispersed using a three-roll mill. To this was added 45 parts of an active ester curing agent (DIC Corporation's "HPC-8000-65T," a toluene solution with an active group equivalent of approximately 223 and a non-volatile content of 65% by mass), 5 parts of a phenoxy resin (weight average molecular weight 35,000, Mitsubishi Chemical Corporation's "YX7553," a 1:1 solution of MEK and cyclohexanone with a non-volatile content of 30% by mass), 3 parts of a curing accelerator (1-benzyl-2-phenylimidazole, a 10% by mass MEK solution), and 7 parts of methyl ethyl ketone (MEK). The mixture was then uniformly dispersed using a rotary mixer to produce Resin Composition 1.

[0158] <Preparation Example 2> (Preparation of Resin Composition 2) Resin composition 2 was prepared in the same manner as in Preparation Example 1, except that inorganic filler 2 was used instead of inorganic filler 1.

[0159] Preparation Example 3 (Preparation of Resin Composition 3) Resin composition 3 was prepared in the same manner as in Preparation Example 1, except that inorganic filler 3 was used instead of inorganic filler 1.

[0160] Preparation Example 4 (Preparation of Resin Composition 4) Resin composition 4 was prepared in the same manner as in Preparation Example 1, except that inorganic filler 4 was used instead of inorganic filler 1.

[0161] [Example 1] (1) Preparation of resin sheet A PET film (38 μm thick, "release PET") that had been release-treated with an alkyd resin-based release agent was prepared as a support. Resin composition 1 was then uniformly applied onto the release layer of the support using a die coater so that the thickness of the resin composition layer after drying would be 40 μm, and the resulting layer was dried at 80 to 110°C (average 95°C) for 5 minutes (residual solvent content in the resin composition layer: approximately 2% by mass). Next, a polypropylene film (15 μm thick) was laminated as a protective film on the side of the resin composition layer that was not bonded to the support. This resulted in a resin sheet having a layer structure of release PET (support), resin composition layer, and protective film.

[0162] (2) Manufacturing of evaluation circuit boards (2-1) Laminating a resin composition layer onto a substrate and thermally curing it The protective film was peeled off from the resin sheet to expose the resin composition layer. A silicon wafer (8-inch size) was prepared as a substrate. Then, using a batch-type vacuum pressure laminator ("MVLP-500" manufactured by Meiki Seisakusho), the resin sheet was laminated on a portion of the silicon wafer so that the resin composition layer was in contact with the silicon wafer. The lamination was performed by reducing the pressure for 30 seconds to 13 hPa or less, followed by pressure bonding at 100°C and a pressure of 0.74 MPa for 30 seconds. The resin composition layer was then cured under the curing conditions (temperature, time) shown in Table 1 to form an insulating layer. After thermal curing, the release PET was peeled off to expose the insulating layer. This substrate is designated as Substrate A.

[0163] (2-2) Chemical mechanical polishing of insulating layer The abrasive for chemical mechanical polishing was prepared by dispersing 200 g of alumina powder (AP-D powder 0.05 μm, manufactured by Struers) in 1 L of water. The surface of the insulating layer of Substrate A was then polished for 5 minutes at 100 rpm using a chemical mechanical polishing machine (LaboForce-100, manufactured by Struers). This substrate was designated Substrate B.

[0164] (2-3) Formation of plating seed layer by sputtering method A plating seed layer was formed by sputtering on the surface of the insulating layer of Substrate B. Specifically, a sputtering device (Canon Anelva Corporation's "E-400S") was used to form a 30 nm thick diffusion barrier layer (Ti layer) on the surface of the insulating layer of Substrate B, and then a 200 nm thick conductive seed layer (Cu layer) was formed, thereby forming a 230 nm thick plating seed layer.

[0165] (2-4) Formation of conductor circuit A conductor circuit was formed using a semi-additive method. Specifically, a photoresist was applied to a substrate on which a plating seed layer had been formed, and then exposed and developed to expose the metal layer corresponding to a comb-tooth pattern with L / S = 2 / 2 μm (line width 1 mm). Next, copper sulfate electrolytic plating was performed to form a conductor layer (conductor circuit) with a thickness of 3 μm on the exposed metal layer, after which the photoresist was removed. Then, etching (seed etching) of the metal layer was performed in the areas where the first conductor circuit was not formed.

[0166] [Example 2] A resin sheet was prepared in the same manner as in Example 1. Then, a circuit board for evaluation was produced in the same manner as in Example 1, except that the curing conditions were changed to those shown in Table 1.

[0167] [Example 3] A resin sheet was produced in the same manner as in Example 1, except that Resin Composition 2 was used instead of Resin Composition 1. Using the obtained resin sheet, an evaluation circuit board was produced in the same manner as in Example 1.

[0168] [Example 4] A resin sheet was produced in the same manner as in Example 1, except that Resin Composition 3 was used instead of Resin Composition 1. Using the obtained resin sheet, an evaluation circuit board was produced in the same manner as in Example 1.

[0169] [Example 5] A resin sheet was produced in the same manner as in Example 1, except that Resin Composition 4 was used instead of Resin Composition 1. Using the obtained resin sheet, a circuit board for evaluation was produced in the same manner as in Example 1.

[0170] [Comparative Examples 1 and 2] A resin sheet was prepared in the same manner as in Example 1. Then, a circuit board for evaluation was produced in the same manner as in Example 1, except that the curing conditions were changed to those shown in Table 1.

[0171] Various measurement and evaluation methods will be explained.

[0172] <Removal volume and removal rate of chemical mechanical polishing> The amount of polishing (thickness; μm) and polishing rate (μm / min) of chemical mechanical polishing were measured and calculated as follows. First, for Substrate A, the step height H1 (μm) between the silicon wafer surface and the insulating layer surface was measured using a laser microscope (Keyence Corporation, "VK-X3000"). Next, for Substrate B after polishing, the step height H2 (μm) between the silicon wafer surface and the insulating layer surface was measured using the same laser microscope. The amount of polishing (μm) was calculated as the difference between H1 and H2, i.e., H1 - H2. The polishing rate (μm / min) was calculated using the formula: (H1 - H2) / 5.

[0173] <Surface roughness of insulating layer after chemical mechanical polishing> The polished surface of the insulating layer of substrate B was used as the measurement surface, and the arithmetic mean roughness Ra (nm) was measured using a non-contact surface roughness meter (WYKO NT3300 manufactured by Veeco Instruments) in VSI mode with a 50x lens over a measurement range of 121 μm × 92 μm.

[0174] <Measurement of Glass Transition Temperature of Resin Composition> (1) Measurement of glass transition temperature Tg1 Each resin composition was cured under the curing conditions shown in Table 1 to obtain a cured sample. Specifically, the insulating layer of Substrate A was used as the cured sample. The cured sample was measured in tensile mode using a dynamic mechanical analyzer (DMA; Seiko Instruments Inc., DMS-6100). The measurement was carried out in the range of 25°C to 240°C at a temperature rise rate of 2°C / min. The glass transition temperature Tg1 (°C) was determined by rounding the temperature (°C) at which the loss tangent (tanδ), calculated as the ratio of the obtained storage modulus (E') to the loss modulus (E"), reached its maximum value.

[0175] (2) Measurement of glass transition temperature Tg2 The protective film was peeled off from the prepared resin sheet, and the resin was cured at 200°C for 120 minutes, after which the release PET film was peeled off to obtain a cured sample. The obtained cured sample was subjected to dynamic mechanical analysis in the same manner as in (1) above to measure the glass transition temperature Tg2 (°C).

[0176] <Surface observation of insulating layer after chemical mechanical polishing> The surface of the insulating layer of substrate B was observed using a scanning electron microscope (SEM) in a field of view of 10k (N=10), and the number of depressions caused by the loss of inorganic filler was counted. If the average number of depressions per field of view was less than 10, it was marked as "Good", and if the average number was 10 or more, it was marked as "Poor".

[0177] [Table 1]

[0178] In all of Examples 1 to 5, in which step (X) was performed so that 0.5≦Tg1 / Tg2≦0.9 was satisfied, it was confirmed that a polishing rate of 1 μm / min or more was achieved when chemically polishing the insulating layer, and an insulating layer with small surface roughness was obtained. On the other hand, in Comparative Examples 1 and 2, in which step (X) was performed under conditions in which Tg1 / Tg2 did not satisfy the range of the present invention, it was confirmed that the polishing rate was poor when chemically polishing the insulating layer, and an insulating layer with large surface roughness was obtained. In the above examples, the results of examining a resin composition containing an epoxy resin as a thermosetting resin are shown. However, it has been confirmed that even when a resin composition containing other thermosetting resins such as a polyarylene ether resin or a radically polymerizable resin is used, by performing step (X) so that 0.5≦Tg1 / Tg2≦0.9 is satisfied, the object of the present invention can be achieved, i.e., in the production of a circuit board by chemically mechanically polishing an insulating layer, a high polishing rate can be achieved and an insulating layer with small surface roughness can be obtained.

Claims

1. The following steps (X), (Y) and (Z): (X) forming a resin composition layer from the resin composition R on a substrate having conductor pillars for interlayer connection on its surface so as to embed the conductor pillars, and curing the resin composition layer to form an insulating layer; (Y) polishing the insulating layer by chemical mechanical polishing (CMP) to expose the conductor pillars; and (Z) Step of forming a plating seed layer on the surface of the insulating layer A method for manufacturing a circuit board, comprising: The content of the inorganic filler is 40% by mass or more, when the non-volatile components in the resin composition R are 100% by mass, A method for manufacturing a circuit board, wherein step (X) is performed so that 0.5≦Tg1 / Tg2≦0.9 is satisfied, where Tg1 is the glass transition temperature (°C) of a cured product obtained by curing resin composition R under the curing conditions in step (X), and Tg2 is the glass transition temperature (°C) of a cured product obtained by curing resin composition R at 200°C for 120 minutes.

2. The following steps (X), (Y) and (Z): (X) forming a resin composition layer from the resin composition R on a substrate having conductor pillars for interlayer connection on its surface so as to embed the conductor pillars, and curing the resin composition layer to form an insulating layer; (Y) polishing the insulating layer by chemical mechanical polishing (CMP) to expose the conductor pillars; and (Z) Step of forming a plating seed layer on the surface of the insulating layer A method for manufacturing a circuit board, comprising: A method for manufacturing a circuit board, wherein step (X) is performed so that 0.5≦Tg1 / Tg2≦0.8 is satisfied, where Tg1 is the glass transition temperature (°C) of a cured product obtained by curing resin composition R under the curing conditions in step (X), and Tg2 is the glass transition temperature (°C) of a cured product obtained by curing resin composition R at 200°C for 120 minutes.

3. The following steps (X), (Y) and (Z): (X) forming a resin composition layer from the resin composition R on a substrate having conductor pillars for interlayer connection on its surface so as to embed the conductor pillars, and curing the resin composition layer to form an insulating layer; (Y) polishing the insulating layer by chemical mechanical polishing (CMP) at a polishing rate of 1.6 μm / min or more to expose the conductor pillars; and (Z) Step of forming a plating seed layer on the surface of the insulating layer A method for manufacturing a circuit board, comprising: A method for manufacturing a circuit board, wherein step (X) is performed so that 0.5≦Tg1 / Tg2≦0.9 is satisfied, where Tg1 is the glass transition temperature (°C) of a cured product obtained by curing resin composition R under the curing conditions in step (X), and Tg2 is the glass transition temperature (°C) of a cured product obtained by curing resin composition R at 200°C for 120 minutes.

4. 4. The method according to claim 1, wherein in step (Z), the plating seed layer is formed by a sputtering method.

5. The method according to any one of claims 1 to 3, wherein the step (X) comprises laminating a resin sheet comprising a support and a resin composition layer provided on the support onto a substrate so that the resin composition layer is bonded to the conductor pillar.

6. 4. The method according to claim 1, wherein the polishing amount (thickness) of the insulating layer in step (Y) is 1 μm or more.

7. 3. The method according to claim 1, wherein the polishing rate of the insulating layer in step (Y) is 1 μm / min or more.

8. The method described in claim 7, wherein the polishing rate of the insulating layer in step (Y) is 1.6 μm / min or more.

9. 4. The method according to claim 1, wherein the polished surface of the insulating layer obtained in step (Y) has an arithmetic mean roughness Ra of 70 nm or less.

10. 4. The method according to claim 1, wherein the plating seed layer formed in step (Z) has a thickness of 500 nm or less.

11. The method according to any one of claims 1 to 3, further comprising the step of forming a conductor layer on the plating seed layer by electrolytic plating.

12. The method according to any one of claims 1 to 3, wherein the resin composition R comprises a thermosetting resin.

13. The method according to claim 2 or 3, wherein the content of the inorganic filler in the resin composition R is 40% by mass or more, when the non-volatile components in the resin composition R are 100% by mass.

14. The method according to any one of claims 1 to 3, wherein the resin composition R contains an inorganic filler treated with an alkoxy group-containing surface treatment agent.

15. The method according to claim 14, wherein the alkoxy group-containing surface treatment agent is at least one selected from the group consisting of an alkoxy group-containing silane coupling agent and an oligomer thereof.

16. The amount of carbon per unit surface area of ​​the inorganic filler is 0.05 mg / m ２ The method according to claim 14 .

17. The method according to any one of claims 1 to 3, wherein Tg2 is 150°C or higher.

18. A method described in claim 1 or 3, wherein step (X) is carried out so that 0.5≦Tg1 / Tg2≦0.8 is satisfied.

19. The method according to any one of claims 1 to 3, wherein the circuit board is for a semiconductor package.

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