JP7560398B2 - Resin composition - Google Patents

Description

The present invention relates to a resin composition containing an epoxy resin. It also relates to a resin sheet, a printed wiring board, and a semiconductor device obtained by using the resin composition.

A known manufacturing technique for printed wiring boards is the build-up method, in which insulating layers and conductor layers are alternately stacked. In build-up manufacturing methods, the insulating layers are generally formed by curing a resin composition. In recent years, there has been a demand to keep the dielectric tangent of the insulating layer lower.

JP 2018-197282 A International Publication No. 2020/129724

It has been known that the dielectric tangent of an insulating layer can be reduced by using an epoxy resin composition containing an active ester compound as a resin composition for forming the insulating layer (Patent Document 1). However, when an epoxy resin composition containing an active ester compound is used, problems such as reduced smear removal and reduced elongation at break have been encountered.

Note that 2,6-xylenol-dicyclopentadiene type epoxy resins have been known to date (Patent Document 2).

The object of the present invention is to provide a resin composition (for forming an interlayer insulating layer of a printed wiring board) that can produce a cured product having a low dielectric tangent and excellent smear removal properties and elongation at break.

In order to achieve the object of the present invention, the inventors conducted extensive research and unexpectedly discovered that by using a resin composition containing (A) an epoxy resin, (B) an active ester compound, and (C) an inorganic filler, in which component (A) contains a specific epoxy resin described below, it is possible to obtain a cured product that has a low dielectric tangent and excellent smear removal properties and elongation at break, and thus completed the present invention.

That is, the present invention includes the following.
[1] A resin composition comprising (A) an epoxy resin, (B) an active ester compound, and (C) an inorganic filler,
The component (A) is represented by formula (A-1) (1):

[Wherein,
R ¹ is each independently a hydrogen atom, a group represented by formula (1a), or a group represented by formula (1b), and at least one R ¹ is a group represented by formula (1a) or a group represented by formula (1b):

(In formulas (1a) and (1b), * indicates a binding site.)
R ² and R ³ each independently represent a hydrocarbon group having 1 to 8 carbon atoms;
n is an integer of 0 or more and indicates the number of repeating units.
A resin composition for forming an interlayer insulating layer of a printed wiring board, comprising an epoxy resin represented by the formula:
[2] The resin composition for forming an interlayer insulating layer of a printed wiring board according to the above [1], wherein the average value of n is within the range of 0 to 5.
[3] The resin composition for forming an interlayer insulating layer of a printed wiring board according to the above [1] or [2], wherein the component (A) further comprises an epoxy resin that is liquid at a temperature of 20° C.
[4] The resin composition for forming an interlayer insulating layer of a printed wiring board according to any one of the above [1] to [3], wherein the content of the component (A) is 1 to 30 mass % when the total amount of non-volatile components in the resin composition is 100 mass %.
[5] The resin composition for forming an interlayer insulating layer of a printed wiring board according to any one of [1] to [4] above, wherein the content of the component (B) is 5% by mass or more, based on 100% by mass of non-volatile components in the resin composition.
[6] The resin composition for forming an interlayer insulating layer of a printed wiring board according to any one of the above [1] to [5], wherein the component (C) is silica.
[7] The resin composition for forming an interlayer insulating layer of a printed wiring board according to any one of [1] to [6] above, wherein the content of the component (C) is 40 mass% or more, when the non-volatile components in the resin composition are 100 mass%.
[8] The resin composition for forming an interlayer insulating layer of a printed wiring board according to any one of the above [1] to [7], further comprising a phenoxy resin.
[9] The resin composition for forming an interlayer insulating layer of a printed wiring board according to any one of the above [1] to [8], further comprising a phenol-based curing agent.
[10] The resin composition for forming an interlayer insulating layer of a printed wiring board according to any one of [1] to [9] above, wherein the elongation at break of a cured product of the resin composition is 1.0% or more when measured at 23°C in accordance with JIS K7127.
[11] The resin composition for forming an interlayer insulating layer of a printed wiring board according to any one of [1] to [10] above, wherein the dielectric loss tangent (Df) of a cured product of the resin composition is 0.0040 or less when measured at 5.8 GHz and 23°C.
[12] The resin composition for forming an interlayer insulating layer of a printed wiring board according to any one of [1] to [11] above, wherein the dielectric constant (Dk) of a cured product of the resin composition is 3.5 or less when measured at 5.8 GHz and 23°C.
[13] A resin sheet having a support and a resin composition layer provided on the support,
the resin composition layer contains (A) an epoxy resin, (B) an active ester compound, and (C) an inorganic filler;
The component (A) is represented by formula (A-1) (1):

[Wherein,
R ¹ is each independently a hydrogen atom, a group represented by formula (1a), or a group represented by formula (1b), and at least one R ¹ is a group represented by formula (1a) or a group represented by formula (1b):

(In formulas (1a) and (1b), * indicates a binding site.)
R ² and R ³ each independently represent a hydrocarbon group having 1 to 8 carbon atoms;
n is an integer of 0 or more and indicates the number of repeating units.
The resin sheet for forming an interlayer insulating layer of a printed wiring board is a resin composition layer formed from a resin composition containing an epoxy resin represented by the formula:
[14] A resin composition comprising (A) an epoxy resin, (B) an active ester compound, and (C) an inorganic filler,
The component (A) is represented by formula (A-1) (1):

[Wherein,
R ¹ is each independently a hydrogen atom, a group represented by formula (1a), or a group represented by formula (1b), and at least one R ¹ is a group represented by formula (1a) or a group represented by formula (1b):

(In formulas (1a) and (1b), * indicates a binding site.)
R ² and R ³ each independently represent a hydrocarbon group having 1 to 8 carbon atoms;
n is an integer of 0 or more and indicates the number of repeating units.
A printed wiring board having an insulating layer made of a cured product of a resin composition containing an epoxy resin represented by the formula:
[15] A semiconductor device comprising the printed wiring board according to [14] above.

The resin composition of the present invention can produce a cured product that has a low dielectric tangent and excellent smear removal properties and elongation at break.

The present invention will be described in detail below based on its preferred embodiments. However, the present invention is not limited to the following embodiments and examples, and can be modified as desired without departing from the scope of the claims of the present invention and their equivalents.

<Resin Composition>
The resin composition of the present invention is a resin composition for forming an interlayer insulating layer of a printed wiring board (a resin composition for forming an interlayer insulating layer of a printed wiring board). In the present invention, the interlayer insulating layer of a printed wiring board also includes a rewiring formation layer of a semiconductor package.

The resin composition of the present invention contains (A) an epoxy resin, (B) an active ester compound, and (C) an inorganic filler, and the component (A) contains the specific epoxy resin (A-1) described below. By using such a resin composition, it is possible to obtain a cured product having a low dielectric tangent and excellent smear removal properties and elongation at break.

The resin composition of the present invention may further contain optional components in addition to (A) the epoxy resin, (B) the active ester compound, and (C) the inorganic filler. Examples of optional components include (B') other curing agents, (D) thermoplastic resins, (E) curing accelerators, (F) other additives, and (G) organic solvents. Each component contained in the resin composition will be described in detail below.

<(A) Epoxy Resin>
The resin composition of the present invention contains an epoxy resin (A). The epoxy resin (A) is a curable resin having an epoxy group and an epoxy equivalent of 5,000 g/eq. or less.

<(A-1) Specific Epoxy Resin>
In the resin composition of the present invention, the epoxy resin (A) is represented by formula (A-1) (1):

[Wherein,
R ¹ is each independently a hydrogen atom, a group represented by formula (1a), or a group represented by formula (1b), and at least one R ¹ is a group represented by formula (1a) or a group represented by formula (1b):

(In formulas (1a) and (1b), * indicates a binding site.)
R ² and R ³ each independently represent a hydrocarbon group having 1 to 8 carbon atoms;
n is an integer of 0 or more and indicates the number of repeating units.
The epoxy resin (hereinafter may be referred to as a "specific epoxy resin") represented by the formula: The units represented by n may be the same or different for each unit.

R ¹ 's each independently represent a hydrogen atom, a group represented by formula (1a), or a group represented by formula (1b), and at least one R ¹ is a group represented by formula (1a) or a group represented by formula (1b).

^R2 and ^R3 each independently represent a hydrocarbon group having 1 to 8 carbon atoms. ^R2 and ^R3 each independently represent preferably an alkyl group having 1 to 6 carbon atoms or a phenyl group, more preferably a methyl group, an ethyl group, a propyl group, or an isopropyl group, and even more preferably a methyl group.

A hydrocarbon group is a monovalent group whose skeletal atoms are only carbon atoms, and may have a straight-chain structure, a branched-chain structure, and/or a cyclic structure, and may be a group that does not contain an aromatic ring or a group that contains an aromatic ring. Examples of hydrocarbon groups having 1 to 8 carbon atoms include alkyl groups having 1 to 8 carbon atoms, alkenyl groups having 2 to 8 carbon atoms, aralkyl groups having 7 or 8 carbon atoms, alkylaryl groups having 7 or 8 carbon atoms, and phenyl groups.

The term "alkyl group" refers to a linear, branched and/or cyclic monovalent aliphatic saturated hydrocarbon group. The alkyl group having 1 to 8 carbon atoms is preferably an alkyl group having 1 to 6 carbon atoms, and more preferably an alkyl group having 1 to 3 carbon atoms. Examples of the alkyl group having 1 to 8 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a cyclopentyl group, a cyclohexyl group, a 4-methylcyclohexyl group, a 2,4-dimethylcyclohexyl group, a cyclopentylmethyl group, and a cyclohexylmethyl group.

The term "alkenyl group" refers to a linear, branched, and/or cyclic monovalent aliphatic unsaturated hydrocarbon group having at least one carbon-carbon double bond. The alkenyl group having 2 to 8 carbon atoms is preferably an alkenyl group having 2 to 6 carbon atoms, and more preferably an alkenyl group having 2 or 3 carbon atoms. Examples of the alkenyl group having 2 to 8 carbon atoms include a vinyl group, a propenyl group (allyl group, 1-propenyl group, isopropenyl group), a butenyl group (1-butenyl group, crotyl group, methallyl group, isocrotyl group, etc.), a pentenyl group (1-pentenyl group, etc.), a hexenyl group (1-hexenyl group, etc.), a heptenyl group (1-heptenyl group, etc.), an octenyl group (1-octenyl group, etc.), a cyclopentenyl group (2-cyclopentenyl group, etc.), a cyclohexenyl group (3-cyclohexenyl group, etc.), etc.

An aralkyl group refers to a monovalent aliphatic saturated hydrocarbon group substituted with a monovalent aromatic hydrocarbon group composed of an aromatic carbon ring. Examples of aralkyl groups having 7 or 8 carbon atoms include a benzyl group, a phenethyl group, and an α-methylbenzyl group.

The term "alkylaryl group" refers to a monovalent aromatic hydrocarbon group composed of an aromatic carbon ring substituted with a monovalent aliphatic saturated hydrocarbon group. Examples of alkylaryl groups having 7 or 8 carbon atoms include 4-methylphenyl, 3-methylphenyl, 2-methylphenyl, 2,4-dimethylphenyl, 3,4-dimethylphenyl, 4-ethylphenyl, 3-ethylphenyl, and 2-ethylphenyl groups.

n is an integer of 0 or more, and indicates the number of repeating units. The average value of n is preferably 0 or more, more preferably 0.01 or more, even more preferably 0.1 or more, even more preferably 0.3 or more, even more preferably 0.5 or more, and particularly preferably 0.6 or more, and the upper limit is preferably 5 or less, more preferably 2 or less, even more preferably 1.5 or less, and particularly preferably 1 or less.

The epoxy equivalent of the specific epoxy resin (A-1) is preferably 3,700 g/eq. or less, more preferably 2,000 g/eq. or less, and particularly preferably 700 g/eq. or less. The lower limit is not particularly limited, but is preferably 244 g/eq. or more, more preferably 260 g/eq. or more, and particularly preferably 270 g/eq. or more. The epoxy equivalent is the mass of the resin per equivalent of epoxy groups. This epoxy equivalent can be measured according to JIS K7236.

(A-1) The specific epoxy resin can be produced, for example, using the method described in WO 2020/129724 or a method equivalent thereto.

The content of the specific epoxy resin (A-1) relative to the total non-volatile components in the resin composition is not particularly limited, but is preferably 50% by mass or less, more preferably 40% by mass or less, even more preferably 30% by mass or less, even more preferably 20% by mass or less, and particularly preferably 15% by mass or less, when the non-volatile components in the resin composition are taken as 100% by mass. The lower limit of the content of the specific epoxy resin (A-1) relative to the total non-volatile components is not particularly limited, but is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, even more preferably 1% by mass or more, even more preferably 3% by mass or more, and particularly preferably 5% by mass or more, when the non-volatile components in the resin composition are taken as 100% by mass, from the viewpoint of obtaining the effects of the present invention more significantly.

The content of the specific epoxy resin (A-1) relative to the total epoxy resin (A) in the resin composition is not particularly limited, but is preferably 90% by mass or less, more preferably 80% by mass or less, and particularly preferably 70% by mass or less, when the total epoxy resin (A) in the resin composition is taken as 100% by mass. The lower limit of the content of the specific epoxy resin (A-1) relative to the total epoxy resin (A) is not particularly limited, but is preferably 10% by mass or more, more preferably 30% by mass or more, and particularly preferably 50% by mass or more, from the viewpoint of obtaining the effects of the present invention more significantly, when the total epoxy resin (A) in the resin composition is taken as 100% by mass.

<(A-2) Other Epoxy Resins>
In the resin composition of the present invention, the epoxy resin (A) may contain other epoxy resins (A-2) as optional components. The other epoxy resins (A-2) are components that do not fall under the category of component (A-1).

(A-2) Other epoxy resins include, for example, bixylenol type epoxy resins, bisphenol A type epoxy resins, bisphenol F type epoxy resins, bisphenol S type epoxy resins, bisphenol AF type epoxy resins, dicyclopentadiene type epoxy resins, trisphenol type epoxy resins, naphthol novolac type epoxy resins, phenol novolac type epoxy resins, tert-butyl-catechol type epoxy resins, naphthalene type epoxy resins, naphthol type epoxy resins, anthracene type epoxy resins, glycidylamine ... Examples of the epoxy resins include diethyl ester type epoxy resins, cresol novolac type epoxy resins, phenol aralkyl type epoxy resins, biphenyl type epoxy resins, linear aliphatic epoxy resins, epoxy resins having a butadiene structure, alicyclic epoxy resins, heterocyclic epoxy resins, spiro ring-containing epoxy resins, cyclohexane type epoxy resins, cyclohexane dimethanol type epoxy resins, naphthylene ether type epoxy resins, trimethylol type epoxy resins, tetraphenylethane type epoxy resins, isocyanurate type epoxy resins, phenolphthalimidine type epoxy resins, etc. (A-2) Other epoxy resins may be used alone or in combination of two or more.

The resin composition preferably contains, as the other epoxy resin (A-2), an epoxy resin having two or more epoxy groups in one molecule. The proportion of the epoxy resin having two or more epoxy groups in one molecule relative to 100% by mass of the non-volatile components of the other epoxy resin (A-2) is preferably 50% by mass or more, more preferably 60% by mass or more, and particularly preferably 70% by mass or more.

Epoxy resins include epoxy resins that are liquid at a temperature of 20°C (hereinafter sometimes referred to as "liquid epoxy resins") and epoxy resins that are solid at a temperature of 20°C (hereinafter sometimes referred to as "solid epoxy resins"). (A) Epoxy resin may contain only liquid epoxy resins as (A-2) other epoxy resins, or may contain only solid epoxy resins, or may contain a combination of liquid epoxy resins and solid epoxy resins. (A) Epoxy resin preferably contains liquid epoxy resins as (A-2) other epoxy resins.

Preferably, the liquid epoxy resin has two or more epoxy groups in one molecule.

As liquid epoxy resins, glycirol type epoxy resins, bisphenol A type epoxy resins, bisphenol F type epoxy resins, bisphenol AF type epoxy resins, naphthalene type epoxy resins, glycidyl ester type epoxy resins, glycidyl amine type epoxy resins, phenol novolac type epoxy resins, alicyclic epoxy resins having an ester skeleton, cyclohexane dimethanol type epoxy resins, cyclic aliphatic glycidyl ethers, and epoxy resins having a butadiene structure are preferred, and glycirol type epoxy resins, cyclic aliphatic glycidyl ethers, bisphenol A type epoxy resins, and bisphenol F type epoxy resins are more preferred.

Specific examples of liquid epoxy resins include Nagase ChemteX's "EX-992L," Mitsubishi Chemical's "YX7400," DIC's "HP4032," "HP4032D," and "HP4032SS" (naphthalene-type epoxy resins); Mitsubishi Chemical's "828US," "828EL," "jER828EL," "825," and "Epicoat 828EL" (bisphenol A-type epoxy resins); Mitsubishi Chemical's "jER807" and "1750" (bisphenol A-type epoxy resins). phenol F type epoxy resin); Mitsubishi Chemical Corporation's "jER152" (phenol novolac type epoxy resin); Mitsubishi Chemical Corporation's "630", "630LSD", and "604" (glycidylamine type epoxy resin); ADEKA Corporation's "ED-523T" (glycilol type epoxy resin); ADEKA Corporation's "EP-3950L" and "EP-3980S" (glycidylamine type epoxy resin); ADEKA Corporation's "EP-4088S" (dicyclopentasiloxane type epoxy resin); bisphenol A type epoxy resin); "ZX1059" manufactured by Nippon Steel Chemical & Material Co., Ltd. (mixture of bisphenol A type epoxy resin and bisphenol F type epoxy resin); "EX-721" manufactured by Nagase ChemteX Corporation (glycidyl ester type epoxy resin); "EX-991L" manufactured by Nagase ChemteX Corporation (alkyleneoxy skeleton and butadiene skeleton-containing epoxy resin); "Celloxide 2021P" manufactured by Daicel Corporation (alicyclic epoxy resin having an ester skeleton) Examples include Daicel's "PB-3600", Nippon Soda's "JP-100" and "JP-200" (epoxy resins with butadiene structure); Nippon Steel Chemical & Material's "ZX1658" and "ZX1658GS" (liquid 1,4-glycidylcyclohexane type epoxy resin); Osaka Gas Chemical's "EG-280" (fluorene structure-containing epoxy resin); and Nagase ChemteX's "EX-201" (cyclic aliphatic glycidyl ether).

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

Preferred solid epoxy resins are bixylenol type epoxy resins, naphthalene type epoxy resins, naphthalene type tetrafunctional epoxy resins, naphthol novolac type epoxy resins, cresol novolac type epoxy resins, dicyclopentadiene type epoxy resins, trisphenol type epoxy resins, naphthol type epoxy resins, biphenyl type epoxy resins, naphthylene ether type epoxy resins, anthracene type epoxy resins, bisphenol A type epoxy resins, bisphenol AF type epoxy resins, phenol aralkyl type epoxy resins, tetraphenylethane type epoxy resins, and phenolphthalimidine type epoxy resins.

Specific examples of solid epoxy resins include DIC's "HP4032H" (naphthalene type epoxy resin); DIC's "HP-4700" and "HP-4710" (naphthalene type tetrafunctional epoxy resin); DIC's "N-690" (cresol novolac type epoxy resin); DIC's "N-695" (cresol novolac type epoxy resin); DIC's "HP-7200", "HP-7200HH", "HP-7200H", and "HP-7200L" (dicyclopentadiene type epoxy resin); and DIC's "EXA-7311". , "EXA-7311-G3", "EXA-7311-G4", "EXA-7311-G4S", "HP6000" (naphthylene ether type epoxy resin); "EPPN-502H" (trisphenol type epoxy resin) manufactured by Nippon Kayaku Co., Ltd.; "NC7000L" (naphthol novolac type epoxy resin) manufactured by Nippon Kayaku Co., Ltd.; "NC3000H", "NC3000", "NC3000L", "NC3000FH", "NC3100" (biphenyl type epoxy resin) manufactured by Nippon Steel Chemical & Material Co., Ltd.; "ESN475V", "ESN4 100V (naphthalene type epoxy resin); "ESN485" (naphthol type epoxy resin) manufactured by Nippon Steel Chemical & Material Co., Ltd.; "ESN375" (dihydroxynaphthalene type epoxy resin) manufactured by Nippon Steel Chemical & Material Co., Ltd.; "YX4000H", "YX4000", "YX4000HK", and "YL7890" (bixylenol type epoxy resin) manufactured by Mitsubishi Chemical Co., Ltd.; "YL6121" (biphenyl type epoxy resin) manufactured by Mitsubishi Chemical Co., Ltd.; "YX8800" (anthracene type epoxy resin) manufactured by Mitsubishi Chemical Co., Ltd.; "Y Examples of such epoxy resins include "X7700" (phenol aralkyl type epoxy resin); "PG-100" and "CG-500" manufactured by Osaka Gas Chemicals; "YL7760" (bisphenol AF type epoxy resin) manufactured by Mitsubishi Chemical; "YL7800" (fluorene type epoxy resin) manufactured by Mitsubishi Chemical; "jER1010" (bisphenol A type epoxy resin) manufactured by Mitsubishi Chemical; "jER1031S" (tetraphenylethane type epoxy resin) manufactured by Mitsubishi Chemical; and "WHR991S" (phenolphthalimidine type epoxy resin) manufactured by Nippon Kayaku Co., Ltd. These may be used alone or in combination of two or more types.

(A-2) When a liquid epoxy resin and a solid epoxy resin are used in combination as the other epoxy resin, the mass ratio thereof (liquid epoxy resin:solid epoxy resin) is preferably 10:1 to 1:50, more preferably 2:1 to 1:20, and particularly preferably 1:1 to 1:10.

The epoxy equivalent of (A-2) other epoxy resins is preferably 50 g/eq. to 5,000 g/eq., more preferably 60 g/eq. to 2,000 g/eq., even more preferably 70 g/eq. to 1,000 g/eq., and even more preferably 80 g/eq. to 500 g/eq. The epoxy equivalent is the mass of the resin per equivalent of epoxy groups. This epoxy equivalent can be measured according to JIS K7236.

The weight average molecular weight (Mw) of the other epoxy resins (A-2) is preferably 100 to 5,000, more preferably 250 to 3,000, and even more preferably 400 to 1,500. The weight average molecular weight of the resin can be measured as a polystyrene-equivalent value by gel permeation chromatography (GPC).

The content of the (A-2) other epoxy resin relative to the total non-volatile components in the resin composition is not particularly limited, but is preferably 30% by mass or less, more preferably 10% by mass or less, and particularly preferably 5% by mass or less, when the non-volatile components in the resin composition are taken as 100% by mass. The lower limit of the content of the (A-2) other epoxy resin relative to the total non-volatile components is not particularly limited, but is, for example, 0% by mass or more, 0.01% by mass or more, preferably 0.1% by mass or more, more preferably 1% by mass or more, and particularly preferably 3% by mass or more, when the non-volatile components in the resin composition are taken as 100% by mass.

The content of the epoxy resin (A) relative to the total non-volatile components in the resin composition is not particularly limited, but is preferably 70% by mass or less, more preferably 50% by mass or less, even more preferably 30% by mass or less, even more preferably 20% by mass or less, and particularly preferably 15% by mass or less, when the non-volatile components in the resin composition are taken as 100% by mass. The lower limit of the content of the epoxy resin (A) relative to the total non-volatile components is not particularly limited, but is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, even more preferably 1% by mass or more, even more preferably 5% by mass or more, and particularly preferably 10% by mass or more, when the non-volatile components in the resin composition are taken as 100% by mass.

<(B) Active Ester Compound>
The resin composition of the present invention contains an active ester compound (B). The active ester compound (B) may be used alone or in combination of two or more at any ratio. The active ester compound (B) may function as an epoxy resin curing agent that reacts with the epoxy resin (A) to cure the epoxy resin.

(B) As the active ester compound, generally, compounds having two or more highly reactive ester groups in one molecule, such as phenol esters, thiophenol esters, N-hydroxyamine esters, and esters of heterocyclic hydroxy compounds, are preferably used. The active ester compound 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, an active ester compound obtained from a carboxylic acid compound and a hydroxy compound is preferred, and an active ester compound obtained from a carboxylic acid compound and a phenol compound and/or a naphthol compound is more preferred. Examples of the carboxylic acid compound include benzoic acid, acetic acid, succinic acid, maleic acid, itaconic acid, phthalic acid, isophthalic acid, terephthalic acid, and pyromellitic acid. Examples of phenol compounds or naphthol compounds include hydroquinone, resorcin, bisphenol A, bisphenol F, bisphenol S, phenolphthaline, methylated bisphenol A, methylated bisphenol F, methylated bisphenol S, phenol, o-cresol, m-cresol, p-cresol, catechol, α-naphthol, β-naphthol, 1,5-dihydroxynaphthalene, 1,6-dihydroxynaphthalene, 2,6-dihydroxynaphthalene, dihydroxybenzophenone, trihydroxybenzophenone, tetrahydroxybenzophenone, phloroglucin, benzenetriol, dicyclopentadiene-type diphenol compounds, and phenol novolak. Here, "dicyclopentadiene-type diphenol compounds" refer to diphenol compounds obtained by condensing one molecule of dicyclopentadiene with two molecules of phenol.

Specifically, the active ester compound (B) is preferably a dicyclopentadiene-type active ester compound, a naphthalene-type active ester compound containing a naphthalene structure, an active ester compound containing an acetylated product of phenol novolac, or an active ester compound containing a benzoylated product of phenol novolac, and among these, at least one selected from a dicyclopentadiene-type active ester compound and a naphthalene-type active ester compound is more preferable, and a dicyclopentadiene-type active ester compound is even more preferable. As the dicyclopentadiene-type active ester compound, an active ester compound containing a dicyclopentadiene-type diphenol structure is preferable.

(B) Commercially available active ester compounds include, as active ester compounds containing a dicyclopentadiene-type diphenol structure, "EXB9451", "EXB9460", "EXB9460S", "EXB-8000L", "EXB-8000L-65M", "EXB-8000L-65TM", "HPC-8000L-65TM", "HPC-8000", "HPC-8000-65T", "HPC-8000H", and "HPC-8000H-65TM" (manufactured by DIC Corporation); as active ester compounds containing a naphthalene structure, "HP-B-8151-62T", "EXB-8100L-65T", "EXB-8150-60T", and "EXB-8150 -62T", "EXB-9416-70BK", "HPC-8150-60T", "HPC-8150-62T", and "EXB-8" (manufactured by DIC Corporation); as a phosphorus-containing active ester compound, "EXB9401" (manufactured by DIC Corporation); as an active ester compound which is an acetylated product of phenol novolac, "DC808" (manufactured by Mitsubishi Chemical Corporation); as an active ester compound which is a benzoylated product of phenol novolac, "YLH1026", "YLH1030", and "YLH1048" (manufactured by Mitsubishi Chemical Corporation); as an active ester compound containing a styryl group and a naphthalene structure, "PC1300-02-65MA" (manufactured by Air Water Inc.) and the like can be mentioned.

The active ester group equivalent of the (B) active ester compound is preferably 50 g/eq. to 500 g/eq., more preferably 50 g/eq. to 400 g/eq., and even more preferably 100 g/eq. to 300 g/eq. The active ester group equivalent is the mass of the active ester compound per equivalent of the active ester group.

The content of the (B) active ester compound relative to the total non-volatile components in the resin composition is preferably 0.1% by mass or more, more preferably 1% by mass or more, even more preferably 5% by mass or more, and particularly preferably 8% by mass or more, when the non-volatile components in the resin composition are taken as 100% by mass. The upper limit of the content of the (B) active ester compound relative to the total non-volatile components is not particularly limited, but is preferably 50% by mass or less, more preferably 40% by mass or less, even more preferably 30% by mass or less, even more preferably 25% by mass or less, and particularly preferably 20% by mass or less, when the non-volatile components in the resin composition are taken as 100% by mass.

The mass ratio of the active ester compound (B) to the epoxy resin (A) in the resin composition (component (B)/component (A)) is preferably 0.05 or more, more preferably 0.1 or more, and particularly preferably 0.5 or more. The upper limit of the mass ratio of the active ester compound (B) to the epoxy resin (A) in the resin composition (component (B)/component (A)) is preferably 5 or less, more preferably 3 or less, and particularly preferably 1 or less.

<(B') Other Curing Agents>
The resin composition of the present invention may further contain a (B') curing agent other than the (B) component as an optional component. The (B') other curing agent may be used alone or in any combination of two or more. The (B') other curing agent may function as an epoxy resin curing agent that reacts with the (A) epoxy resin to cure it, similar to the (B) active ester compound.

(B') Other curing agents are not particularly limited, but examples thereof include phenol-based curing agents, carbodiimide-based curing agents, acid anhydride-based curing agents, amine-based curing agents, benzoxazine-based curing agents, cyanate ester-based curing agents, and thiol-based curing agents. It is particularly preferable that the resin composition of the present invention contains a phenol-based curing agent from the viewpoint of further improving the curability of the resin composition.

As the phenol-based hardener, a phenol-based hardener having a novolac structure is preferred from the viewpoint of heat resistance and water resistance. Also, from the viewpoint of adhesion to the adherend, a nitrogen-containing phenol-based hardener is preferred, and a triazine skeleton-containing phenol-based hardener is more preferred. Among them, a triazine skeleton-containing phenol novolac resin is preferred from the viewpoint of highly satisfying heat resistance, water resistance, and adhesion. Specific examples of phenol-based curing agents include "MEH-7700", "MEH-7810", and "MEH-7851" manufactured by Meiwa Kasei Co., Ltd., "NHN", "CBN", and "GPH" manufactured by Nippon Kayaku Co., Ltd., "SN-170", "SN-180", "SN-190", "SN-475", "SN-485", "SN-495", "SN-375", and "SN-395" manufactured by Nippon Steel Chemical & Material Co., Ltd., and "LA-7052", "LA-7054", "LA-3018", "LA-3018-50P", "LA-1356", "TD2090", and "TD-2090-60M" manufactured by DIC Corporation.

Carbodiimide-based curing agents include curing agents having one or more, preferably two or more, carbodiimide structures in one molecule, such as aliphatic biscarbodiimides such as tetramethylene-bis(t-butylcarbodiimide) and cyclohexane-bis(methylene-t-butylcarbodiimide); aromatic biscarbodiimides such as phenylene-bis(xylylcarbodiimide); and aliphatic polycarbodiimides such as polyhexamethylenecarbodiimide, polytrimethylhexamethylenecarbodiimide, polycyclohexylenecarbodiimide, poly(methylenebiscyclohexylenecarbodiimide), and poly(isophoronecarbodiimide). ; polycarbodiimides such as aromatic polycarbodiimides such as poly(phenylenecarbodiimide), poly(naphthylenecarbodiimide), poly(tolylenecarbodiimide), poly(methyldiisopropylphenylenecarbodiimide), poly(triethylphenylenecarbodiimide), poly(diethylphenylenecarbodiimide), poly(triisopropylphenylenecarbodiimide), poly(diisopropylphenylenecarbodiimide), poly(xylylenecarbodiimide), poly(tetramethylxylylenecarbodiimide), poly(methylenediphenylenecarbodiimide), and poly[methylenebis(methylphenylene)carbodiimide].

Commercially available carbodiimide curing agents include, for example, "Carbodilite V-02B," "Carbodilite V-03," "Carbodilite V-04K," "Carbodilite V-07," and "Carbodilite V-09" manufactured by Nisshinbo Chemical Co., Ltd.; and "Stavaxol P," "Stavaxol P400," and "Hi-Kasil 510" manufactured by Rhein Chemie.

Examples of acid anhydride curing agents include curing agents having one or more acid anhydride groups in one molecule, and curing agents having two or more acid anhydride groups in one molecule are preferred. 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. anhydride, 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 resin in which styrene and maleic acid are copolymerized. Commercially available acid anhydride curing agents include "HNA-100", "MH-700", "MTA-15", "DDSA", and "OSA" manufactured by New Japan Chemical Co., Ltd., "YH-306" and "YH-307" manufactured by Mitsubishi Chemical Corporation, "HN-2200" and "HN-5500" manufactured by Hitachi Chemical Co., Ltd., and "EF-30", "EF-40", "EF-60", and "EF-80" manufactured by Clay Valley.

Examples of amine-based curing agents include curing agents having one or more, preferably two or more, amino groups in one molecule, such as aliphatic amines, polyether amines, alicyclic amines, and aromatic amines. Among these, aromatic amines are preferred from the viewpoint of achieving the desired effects of the present invention. The amine-based curing agent is preferably a primary amine or secondary amine, and more preferably a primary amine. Specific examples of amine-based curing agents include 4,4'-methylenebis(2,6-dimethylaniline), 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylsulfone, 3,3'-diaminodiphenylsulfone, m-phenylenediamine, m-xylylenediamine, diethyltoluenediamine, 4,4'-diaminodiphenylether, 3,3'-dimethyl-4,4'-diaminobiphenyl, 2,2'-dimethyl-4,4'-diaminobiphenyl, 3,3'-dihydroxybenzidine, and 2,2-bis(3-amino-4-hydroxyphenyl)propane. 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, bis(4-(3-aminophenoxy)phenyl)sulfone, and the like. Commercially available amine-based curing agents may be used, such as "SEIKACURE-S" manufactured by Seika Corporation, "KAYABOND C-200S", "KAYABOND C-100", "KAYAHARD A-A", "KAYAHARD A-B", and "KAYAHARD A-S" manufactured by Nippon Kayaku Co., Ltd., and "Epicure W" manufactured by Mitsubishi Chemical Corporation.

Specific examples of benzoxazine-based curing agents include "JBZ-OP100D" and "ODA-BOZ" manufactured by JFE Chemical Corporation; "HFB2006M" manufactured by Showa Polymer Co., Ltd.; and "P-d" and "F-a" manufactured by Shikoku Chemical Industry Co., Ltd.

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-cyanate phenylmethane), bis(4-cyanate-3,5-dimethylphenyl)methane, 1,3-bis(4-cyanate phenyl-1-(methylethylidene))benzene, bis(4-cyanate phenyl)thioether, and bis(4-cyanate phenyl)ether; polyfunctional cyanate resins derived from phenol novolac and cresol novolac; and prepolymers in which these cyanate resins have been partially converted to triazine. Specific examples of cyanate ester-based hardeners include Lonza Japan's "PT30" and "PT60" (both of which are phenol novolac-type multifunctional cyanate ester resins), "BA230" and "BA230S75" (prepolymers in which part or all of bisphenol A dicyanate has been converted to triazine and turned into a trimer).

Examples of thiol-based curing agents include trimethylolpropane tris(3-mercaptopropionate), pentaerythritol tetrakis(3-mercaptobutyrate), and tris(3-mercaptopropyl)isocyanurate.

(B') The reactive group equivalent of the other curing agent is preferably 50 g/eq. to 3000 g/eq., more preferably 100 g/eq. to 1000 g/eq., even more preferably 100 g/eq. to 500 g/eq., and particularly preferably 100 g/eq. to 300 g/eq. The reactive group equivalent is the mass of the curing agent per equivalent of reactive group.

The content of the (B') other curing agent relative to the total non-volatile components in the resin composition is not particularly limited, but is preferably 20% by mass or less, more preferably 10% by mass or less, even more preferably 5% by mass or less, and particularly preferably 3% by mass or less, when the non-volatile components in the resin composition are taken as 100% by mass. The lower limit of the content of the (B') other curing agent relative to the total non-volatile components is not particularly limited, but may be, for example, 0% by mass or more, 0.01% by mass or more, 0.1% by mass or more, 1% by mass or more, etc., when the non-volatile components in the resin composition are taken as 100% by mass.

The content of the (B) active ester compound relative to the total hardeners in the resin composition is preferably 10% by mass or more, more preferably 30% by mass or more, even more preferably 40% by mass or more, and particularly preferably 50% by mass or more, assuming that the total hardeners in the resin composition (i.e., the sum of the (B) active ester compound and the (B') other hardeners) is 100% by mass.

<(C) Inorganic filler>
The resin composition of the present invention contains an inorganic filler (C). The inorganic filler (C) is contained in the resin composition in the form of particles.

(C) An inorganic compound is used as the material for the inorganic filler. (C) Examples of the material for the inorganic filler include silica, alumina, glass, cordierite, silicon oxide, barium sulfate, barium carbonate, talc, clay, mica powder, zinc oxide, hydrotalcite, boehmite, aluminum hydroxide, magnesium hydroxide, calcium carbonate, magnesium carbonate, magnesium oxide, boron nitride, aluminum nitride, manganese nitride, aluminum borate, strontium carbonate, strontium titanate, calcium titanate, magnesium titanate, bismuth titanate, titanium oxide, zirconium oxide, barium titanate, barium zirconate titanate, barium zirconate, calcium zirconate, zirconium phosphate, and zirconium tungstate phosphate. Among these, silica is particularly suitable. Examples of silica include amorphous silica, fused silica, crystalline silica, synthetic silica, and hollow silica. In addition, spherical silica is preferable as the silica. (C) The inorganic filler may be used alone or in any combination of two or more kinds in any ratio.

(C) 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 & Sumitomo Metal Materials Co., Ltd.; "YC100C", "YA050C", "YA050C-MJE", and "YA010C" manufactured by Admatechs Co., Ltd.; "UFP-30" manufactured by Denka Company; "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.; and "DAW-03" and "FB-105FD" manufactured by Denka Company, Ltd.

(C) The average particle size of the inorganic filler is not particularly limited, but is preferably 10 μm or less, more preferably 5 μm or less, even more preferably 2 μm or less, even more preferably 1 μm or less, and particularly preferably 0.7 μm or less. (C) The lower limit of the average particle size of the inorganic filler is not particularly limited, but is preferably 0.01 μm or more, more preferably 0.05 μm or more, even more preferably 0.1 μm or more, and particularly preferably 0.2 μm or more. (C) The average particle size of the inorganic filler can be measured by a laser diffraction/scattering method based on the Mie scattering theory. Specifically, the particle size distribution of the inorganic filler is created on a volume basis using a laser diffraction/scattering particle size distribution measuring device, and the median diameter is used as the average particle size. The measurement sample can be prepared by weighing 100 mg of the inorganic filler and 10 g of methyl ethyl ketone into a vial and dispersing it by ultrasonic waves for 10 minutes. The measurement sample was measured using a laser diffraction type particle size distribution measuring device with blue and red light source wavelengths and a flow cell method to measure the volumetric particle size distribution of the inorganic filler, and the average particle size was calculated as the median diameter from the obtained particle size distribution. An example of a laser diffraction type particle size distribution measuring device is the "LA-960" manufactured by Horiba, Ltd.

The specific surface area of the inorganic filler (C) is not particularly limited, but is preferably 0.1 m ² /g or more, more preferably 0.5 m ² /g or more, even more preferably 1 m ² /g or more, and particularly preferably 3 m ² /g or more. The upper limit of the specific surface area of the inorganic filler (C) is not particularly limited, but is preferably 100 m ² /g or less, more preferably 70 m ² /g or less, even more preferably 50 m ² /g or less, and particularly preferably 40 m ² /g or less. The specific surface area of the inorganic filler is obtained by adsorbing nitrogen gas to the sample surface using a specific surface area measuring device (Macsorb HM-1210 manufactured by Mountech Co., Ltd.) according to the BET method, and calculating the specific surface area using the BET multipoint method.

(C) From the viewpoint of improving moisture resistance and dispersibility, it is preferable that the inorganic filler is treated with a surface treatment agent. Examples of the surface treatment agent include a fluorine-containing silane coupling agent, an aminosilane coupling agent, an epoxysilane coupling agent, a mercaptosilane coupling agent, a silane coupling agent, an alkoxysilane, an organosilazane compound, and a titanate coupling agent. In addition, the surface treatment agent may be used alone or in any combination of two or more types.

Examples of commercially available surface treatment agents include Shin-Etsu Chemical's "KBM403" (3-glycidoxypropyltrimethoxysilane), Shin-Etsu Chemical's "KBM803" (3-mercaptopropyltrimethoxysilane), Shin-Etsu Chemical's "KBE903" (3-aminopropyltriethoxysilane), Shin-Etsu Chemical's "KBM573" (N-phenyl-3-aminopropyltrimethoxysilane), Shin-Etsu Chemical's "SZ-31" (hexamethyldisilazane), Shin-Etsu Chemical's "KBM103" (phenyltrimethoxysilane), Shin-Etsu Chemical's "KBM-4803" (long-chain epoxy-type silane coupling agent), Shin-Etsu Chemical's "KBM-7103" (3,3,3-trifluoropropyltrimethoxysilane), and Shin-Etsu Chemical's N-phenyl-8-aminooctyltrimethoxysilane.

From the viewpoint of improving the dispersibility of the inorganic filler, it is preferable that the degree of surface treatment with the surface treatment agent falls within a specified range. Specifically, it is preferable that 100% by mass of the inorganic filler is surface-treated with 0.2% to 5% by mass of the surface treatment agent, more preferably 0.2% to 3% by mass, and even more preferably 0.3% to 2% by mass.

The degree of surface treatment by the surface treatment agent can be evaluated by the amount of carbon per unit surface area of the inorganic filler. From the viewpoint of improving the dispersibility of the inorganic filler, the amount of carbon per unit surface area of the inorganic filler is preferably 0.02 mg/m ² or more, more preferably 0.1 mg/m ² or more, and even more preferably 0.2 mg/m ² or more. On the other hand, from the viewpoint of preventing an increase in the melt viscosity of the resin composition or the melt viscosity in the sheet form, it is preferably 1.0 mg/m ² or less, more preferably 0.8 mg/m ² or less, and even more preferably 0.5 mg/m ² or less.

(C) The amount of carbon 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 solids, the amount of carbon per unit surface area of the inorganic filler can be measured using a carbon analyzer. An example of a carbon analyzer that can be used is the "EMIA-320V" manufactured by Horiba, Ltd.

The content of the inorganic filler (C) relative to the total non-volatile components in the resin composition is not particularly limited, but is preferably 90% by mass or less, more preferably 85% by mass or less, even more preferably 80% by mass or less, and particularly preferably 75% by mass or less, when the non-volatile components in the resin composition are taken as 100% by mass. The lower limit of the content of the inorganic filler (C) relative to the total non-volatile components is not particularly limited, but is preferably 40% by mass or more, more preferably 50% by mass or more, even more preferably 60% by mass or more, even more preferably 65% by mass or more, and particularly preferably 70% by mass or more, when the non-volatile components in the resin composition are taken as 100% by mass.

The mass ratio of the inorganic filler (C) to the epoxy resin (A) in the resin composition (component (C)/component (A)) is preferably 0.5 or more, more preferably 1 or more, and particularly preferably 3 or more. The upper limit of the mass ratio of the inorganic filler (C) to the epoxy resin (A) in the resin composition (component (C)/component (A)) is preferably 50 or less, more preferably 30 or less, and particularly preferably 10 or less.

<(D) Thermoplastic resin>
The resin composition of the present invention may further contain a thermoplastic resin (D) as an optional component. The thermoplastic resin (D) described here is a component that does not fall under the category of the epoxy resin (A).

(D) Examples of thermoplastic resins include polyimide resins, phenoxy resins, polyvinyl acetal resins, polyolefin resins, polybutadiene resins, polyamideimide resins, polyetherimide resins, polysulfone resins, polyethersulfone resins, polyphenylene ether resins, polycarbonate resins, polyetheretherketone resins, and polyester resins. In one embodiment, the resin composition of the present invention preferably contains a thermoplastic resin selected from the group consisting of polyimide resins and phenoxy resins, and more preferably contains a phenoxy resin. In addition, the thermoplastic resins may be used alone or in combination of two or more types.

Specific examples of polyimide resins include "SLK-6100" manufactured by Shin-Etsu Chemical Co., Ltd., and "Rikacoat SN20" and "Rikacoat PN20" manufactured by New Japan Chemical Co., Ltd.

Examples of phenoxy resins include phenoxy resins having one or more skeletons selected from the group consisting of bisphenol A skeleton, bisphenol F skeleton, bisphenol S skeleton, bisphenolacetophenone skeleton, novolac skeleton, biphenyl skeleton, fluorene skeleton, dicyclopentadiene skeleton, norbornene skeleton, naphthalene skeleton, anthracene skeleton, adamantane skeleton, terpene skeleton, and trimethylcyclohexane skeleton. The terminal of the phenoxy resin may be any functional group such as a phenolic hydroxyl group or an epoxy group.

Specific examples of phenoxy resins include "1256" and "4250" manufactured by Mitsubishi Chemical Corporation (both phenoxy resins containing a bisphenol A skeleton); "YX8100" manufactured by Mitsubishi Chemical Corporation (phenoxy resin containing a bisphenol S skeleton); "YX6954" manufactured by Mitsubishi Chemical Corporation (phenoxy resin containing a bisphenol acetophenone skeleton); "FX280" and "FX293" manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.; "YL7500BH30", "YX6954BH30", "YX7553", "YX7553BH30", "YL7769BH30", "YL6794", "YL7213", "YL7290", "YL7482", and "YL7891BH30" manufactured by Mitsubishi Chemical Corporation; and the like.

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

Examples of polyolefin resins include ethylene-based 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; polyolefin-based polymers such as polypropylene and ethylene-propylene block copolymer.

Examples of polybutadiene resins include hydrogenated polybutadiene skeleton-containing resins, hydroxyl group-containing polybutadiene resins, phenolic hydroxyl group-containing polybutadiene resins, carboxyl group-containing polybutadiene resins, acid anhydride group-containing polybutadiene resins, epoxy group-containing polybutadiene resins, isocyanate group-containing polybutadiene resins, urethane group-containing polybutadiene resins, polyphenylene ether-polybutadiene resins, etc.

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

An example of a polyethersulfone resin is "PES5003P" manufactured by Sumitomo Chemical Co., Ltd.

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

A specific example of a polyphenylene ether resin is NORYL SA90 manufactured by SABIC. A specific example of a polyetherimide resin is ULTEM manufactured by GE.

Examples of polycarbonate resins include hydroxyl group-containing carbonate resins, phenolic hydroxyl group-containing carbonate resins, carboxyl group-containing carbonate resins, acid anhydride group-containing carbonate resins, isocyanate group-containing carbonate resins, and urethane group-containing carbonate resins. Specific examples of polycarbonate resins include "FPC0220" manufactured by Mitsubishi Gas Chemical Co., Ltd., "T6002" and "T6001" (polycarbonate diols) manufactured by Asahi Kasei Chemicals Corporation, and "C-1090", "C-2090", and "C-3090" (polycarbonate diols) manufactured by Kuraray Co., Ltd. Specific examples of polyether ether ketone resins include "Sumiploy K" manufactured by Sumitomo Chemical Co., Ltd.

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.

The weight average molecular weight (Mw) of the (D) thermoplastic resin is preferably 5,000 or more, more preferably 8,000 or more, even more preferably 10,000 or more, and particularly preferably 20,000 or more, from the viewpoint of obtaining a significant effect of the present invention, and is preferably 100,000 or less, more preferably 70,000 or less, even more preferably 60,000 or less, and particularly preferably 50,000 or less.

The content of the (D) thermoplastic resin relative to the total non-volatile components in the resin composition is not particularly limited, but when the non-volatile components in the resin composition are taken as 100% by mass, it may be preferably 20% by mass or less, more preferably 15% by mass or less, even more preferably 10% by mass or less, even more preferably 5% by mass or less, and particularly preferably 3% by mass or less. The lower limit of the content of the (D) thermoplastic resin relative to the total non-volatile components is not particularly limited, but when the non-volatile components in the resin composition are taken as 100% by mass, it may be, for example, 0% by mass or more, 0.01% by mass or more, 0.1% by mass or more, 1% by mass or more, etc.

<(E) Curing Accelerator>
The resin composition of the present invention may contain a curing accelerator (E) as an optional component. The curing accelerator (E) functions as a curing catalyst that accelerates the curing of the epoxy resin (A).

(E) Examples of the curing accelerator include phosphorus-based curing accelerators, urea-based curing accelerators, guanidine-based curing accelerators, imidazole-based curing accelerators, metal-based curing accelerators, and amine-based curing accelerators. (E) The curing accelerator preferably contains a curing accelerator selected from imidazole-based curing accelerators and amine-based curing accelerators, and more preferably contains an amine-based curing accelerator. (E) The curing accelerator may be used alone or in combination of two or more types.

Examples of phosphorus-based curing accelerators include aliphatic phosphonium salts such as tetrabutylphosphonium bromide, tetrabutylphosphonium chloride, tetrabutylphosphonium acetate, tetrabutylphosphonium decanoate, tetrabutylphosphonium laurate, bis(tetrabutylphosphonium)pyromellitate, tetrabutylphosphonium hydrogenhexahydrophthalate, tetrabutylphosphonium 2,6-bis[(2-hydroxy-5-methylphenyl)methyl]-4-methylphenolate, and di-tert-butylmethylphosphonium tetraphenylborate; methyltriphenylphosphonium bromide, ethyltriphenylphosphonium bromide, propyltriphenylphosphonium bromide, butyltriphenylphosphonium bromide, benzyltriphenylphosphonium chloride, and tetraphenylphosphine. aromatic phosphonium salts such as sulfonium bromide, p-tolyltriphenylphosphonium tetra-p-tolylborate, tetraphenylphosphonium tetraphenylborate, tetraphenylphosphonium tetra-p-tolylborate, triphenylethylphosphonium tetraphenylborate, tris(3-methylphenyl)ethylphosphonium tetraphenylborate, tris(2-methoxyphenyl)ethylphosphonium tetraphenylborate, (4-methylphenyl)triphenylphosphonium thiocyanate, tetraphenylphosphonium thiocyanate, and butyltriphenylphosphonium thiocyanate; aromatic phosphine-borane complexes such as triphenylphosphine-triphenylborane; aromatic phosphine-quinone addition products such as triphenylphosphine-p-benzoquinone addition products; tributylphosphine, tri-t Aliphatic phosphines such as tert-butylphosphine, trioctylphosphine, di-tert-butyl(2-butenyl)phosphine, di-tert-butyl(3-methyl-2-butenyl)phosphine, and tricyclohexylphosphine; dibutylphenylphosphine, di-tert-butylphenylphosphine, methyldiphenylphosphine, ethyldiphenylphosphine, butyldiphenylphosphine, diphenylcyclohexylphosphine, triphenylphosphine, tri-o-tolylphosphine, tri-m-tolylphosphine, tri-p-tolylphosphine, tris(4-ethylphenyl)phosphine, tris(4-propylphenyl)phosphine, tris(4-isopropylphenyl)phosphine, tris(4-butylphenyl)phosphine, tris(4-tert-butylphenyl)phosphine, tris(2,4-dimethylphenyl)phosphine, ) phosphine, tris(2,5-dimethylphenyl)phosphine, tris(2,6-dimethylphenyl)phosphine, tris(3,5-dimethylphenyl)phosphine, tris(2,4,6-trimethylphenyl)phosphine, tris(2,6-dimethyl-4-ethoxyphenyl)phosphine, tris(2-methoxyphenyl)phosphine, tris(4-methoxyphenyl)phosphine, tris(4-ethoxyphenyl)phosphine, tris(4-tert-butoxyphenyl)phosphine, diphenyl-2-pyridylphosphine, 1,2-bis(diphenylphosphino)ethane, 1,3-bis(diphenylphosphino)propane, 1,4-bis(diphenylphosphino)butane, 1,2-bis(diphenylphosphino)acetylene, 2,2'-bis(diphenylphosphino)diphenyl ether and other aromatic phosphines.

Examples of urea-based hardening accelerators include aliphatic dimethylureas such as 1,1-dimethylurea, 1,1,3-trimethylurea, 3-ethyl-1,1-dimethylurea, 3-cyclohexyl-1,1-dimethylurea, and 3-cyclooctyl-1,1-dimethylurea; 3-phenyl-1,1-dimethylurea, 3-(4-chlorophenyl)-1,1-dimethylurea, 3-(3,4-dichlorophenyl)-1,1-dimethylurea, 3-(3-chloro-4-methylphenyl)-1,1-dimethylurea, 3-(2-methylphenyl)-1,1-dimethylurea, 3-(4-methylphenyl)-1,1-dimethylurea, and 3-(3,4-dimethylphenyl)-1,1-dimethylurea. aromatic dimethylureas such as 3-(4-isopropylphenyl)-1,1-dimethylurea, 3-(4-methoxyphenyl)-1,1-dimethylurea, 3-(4-nitrophenyl)-1,1-dimethylurea, 3-[4-(4-methoxyphenoxy)phenyl]-1,1-dimethylurea, 3-[4-(4-chlorophenoxy)phenyl]-1,1-dimethylurea, 3-[3-(trifluoromethyl)phenyl]-1,1-dimethylurea, N,N-(1,4-phenylene)bis(N',N'-dimethylurea), and N,N-(4-methyl-1,3-phenylene)bis(N',N'-dimethylurea) [toluene bisdimethylurea].

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

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

Commercially available imidazole curing accelerators may be used, such as "1B2PZ", "2MZA-PW", and "2PHZ-PW" manufactured by Shikoku Chemical Industry Co., Ltd., and "P200-H50" manufactured by Mitsubishi Chemical Corporation.

Metal-based curing accelerators include, for example, organometallic complexes or organometallic salts of metals such as cobalt, copper, zinc, iron, nickel, manganese, and tin. Specific examples of organometallic complexes include organocobalt complexes such as cobalt (II) acetylacetonate and cobalt (III) acetylacetonate, organocopper complexes such as copper (II) acetylacetonate, organozinc complexes such as zinc (II) acetylacetonate, organoiron complexes such as iron (III) acetylacetonate, organonickel complexes such as nickel (II) acetylacetonate, and organomanganese complexes such as manganese (II) acetylacetonate. Organometallic salts include, for example, zinc octoate, tin octoate, zinc naphthenate, cobalt naphthenate, tin stearate, and zinc stearate.

Examples of amine-based curing accelerators include trialkylamines such as triethylamine and tributylamine, 4-dimethylaminopyridine, benzyldimethylamine, 2,4,6-tris(dimethylaminomethyl)phenol, and 1,8-diazabicyclo(5,4,0)-undecene.

Commercially available amine-based curing accelerators may be used, such as "MY-25" manufactured by Ajinomoto Fine-Techno Co., Ltd.

The content of the (E) curing accelerator in the resin composition is not particularly limited, but is preferably 5% by mass or less, more preferably 1% by mass or less, even more preferably 0.5% by mass or less, and particularly preferably 0.1% by mass or less, when the non-volatile components in the resin composition are taken as 100% by mass. The lower limit of the content of the (E) curing accelerator in the resin composition is not particularly limited, but may be, for example, 0% by mass or more, 0.001% by mass or more, 0.01% by mass or more, etc., when the non-volatile components in the resin composition are taken as 100% by mass.

<(F) Other Additives>
The resin composition of the present invention may further contain any additive as a non-volatile component. Examples of such additives include thermosetting resins such as epoxy acrylate resins, urethane acrylate resins, urethane resins, cyanate resins, benzoxazine resins, unsaturated polyester resins, phenol resins, melamine resins, silicone resins, and epoxy resins; radical polymerizable compounds having 4-vinylphenyl, acryloyl groups, methacryloyl groups, maleimide groups (2,5-dihydro-2,5-dioxo-1H-pyrrol-1-yl groups), and the like; radical polymerization initiators such as peroxide-based radical polymerization initiators and azo-based radical polymerization initiators; organic fillers such as rubber particles; 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-based leveling agents and acrylic polymer-based leveling agents; thickeners such as bentone and montmorillonite; defoaming agents such as ricone-based defoaming agents, acrylic-based defoaming agents, fluorine-based defoaming agents, and vinyl resin-based defoaming agents; ultraviolet absorbers such as benzotriazole-based ultraviolet absorbers; adhesion improvers such as urea silane; adhesion imparting agents such as triazole-based adhesion imparting agents, tetrazole-based adhesion imparting agents, and triazine-based adhesion imparting agents; antioxidants such as hindered phenol-based antioxidants; fluorescent brightening agents such as stilbene derivatives; surfactants such as fluorine-based surfactants and silicone-based surfactants; phosphorus-based flame retardants (e.g., phosphate ester compounds, phosphazene compounds, Examples of the flame retardants include flame retardants 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 anhydride-based stabilizers. (F) Other additives may be used alone or in combination of two or more at any ratio. The content of (F) other additives can be appropriately set by a person skilled in the art.

<(G) Organic Solvent>
The resin composition of the present invention may further contain an arbitrary organic solvent as a volatile component in addition to the non-volatile components described above. As the (G) organic solvent, any known organic solvent may be appropriately used, and the type is not particularly limited. As the (G) organic solvent, for example, ketone-based solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, etc.; ester-based solvents such as methyl acetate, ethyl acetate, butyl acetate, isobutyl acetate, isoamyl acetate, methyl propionate, ethyl propionate, γ-butyrolactone, etc.; ether-based solvents such as tetrahydropyran, tetrahydrofuran, 1,4-dioxane, diethyl ether, diisopropyl ether, dibutyl ether, diphenyl ether, anisole, etc.; alcohol-based solvents such as methanol, ethanol, propanol, butanol, ethylene glycol, etc.; 2-ethoxyethyl acetate, propylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, ethyl diglycol acetate, γ-butyrolactone, methoxypropionic acid, etc. Examples of the organic solvent include ether ester solvents such as methyl lactate, ethyl lactate, methyl 2-hydroxyisobutyrate, and the like; ester alcohol solvents such as 2-methoxypropanol, 2-methoxyethanol, 2-ethoxyethanol, propylene glycol monomethyl ether, diethylene glycol monobutyl ether (butylcarbitol), and the like; amide solvents such as N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, and the like; sulfoxide solvents such as dimethyl sulfoxide, and the like; nitrile solvents such as acetonitrile, propionitrile, and the like; aliphatic hydrocarbon solvents such as hexane, cyclopentane, cyclohexane, and methylcyclohexane, and the like; aromatic hydrocarbon solvents such as benzene, toluene, xylene, ethylbenzene, and trimethylbenzene, and the like. The organic solvent (G) may be used alone or in any combination of two or more kinds at any ratio.

The content of (G) organic solvent in the varnish-like resin composition before drying is not particularly limited, but is, for example, 40% by mass or less, 30% by mass or less, preferably 20% by mass or less, more preferably 10% by mass or less, even more preferably 8% by mass or less, and particularly preferably 6% by mass or less, when the total components in the resin composition are taken as 100% by mass. The content of (G) organic solvent in the resin composition that forms the resin composition layer after drying in the resin sheet is not particularly limited, but is preferably 5% by mass or less, more preferably 3% by mass or less, even more preferably 2% by mass or less, and particularly preferably 1% by mass or less, when the total components in the resin composition are taken as 100% by mass.

<Method of producing resin composition>
The resin composition of the present invention can be produced, for example, by adding (A) epoxy resin, (B) active ester compound, (C) inorganic filler, if necessary (D) thermoplastic resin, if necessary (E) curing accelerator, if necessary (F) other additives, and if necessary (G) organic solvent to an arbitrary preparation vessel in any order and/or simultaneously in part or in whole, and mixing. In addition, the temperature can be appropriately set in the process of adding and mixing each component, and heating and/or cooling may be performed temporarily or throughout. In addition, during or after the process of adding and mixing, the resin composition may be stirred or shaken using a stirring device or shaking device such as a mixer to disperse uniformly. In addition, degassing may be performed under low pressure conditions such as under vacuum at the same time as stirring or shaking.

<Characteristics of Resin Composition>
The resin composition of the present invention comprises (A) an epoxy resin, (B) an active ester compound, and (C) an inorganic filler, and the component (A) comprises the specific epoxy resin (A-1) described above. By using such a resin composition, it is possible to obtain a cured product having a low dielectric tangent and excellent smear removal properties and elongation at break.

The cured product of the resin composition of the present invention may be characterized by excellent elongation at break. Thus, in one embodiment, the elongation at break of the cured product of the resin composition of the present invention, when measured at 23°C in accordance with JIS K7127 as in Test Example 3 below, may be preferably 0.5% or more, more preferably 0.8% or more, even more preferably 1.0% or more, even more preferably 1.2% or more, and particularly preferably 1.4% or more. The upper limit of the elongation at break may usually be 10% or less, 5% or less, etc.

The cured product of the resin composition of the present invention may be characterized by excellent smear removal properties. Thus, in one embodiment, as in Test Example 2 below, when a via hole is formed with a top diameter of 50 μm on the surface of the cured product and a diameter of 40 μm at the bottom of the via hole, and the maximum smear length from the wall surface of the bottom of the via hole is measured after roughening treatment, the maximum smear length may be less than 5 μm.

The cured product of the resin composition of the present invention may be characterized by a low dielectric loss tangent (Df). Thus, in one embodiment, the dielectric loss tangent (Df) of the cured product of the resin composition when measured at 5.8 GHz and 23°C as in Test Example 1 below may be preferably 0.0100 or less, 0.0080 or less, more preferably 0.0070 or less, 0.0060 or less, even more preferably 0.0050 or less, 0.0045 or less, and particularly preferably 0.0040 or less, 0.0035 or less.

In one embodiment, the cured product of the resin composition of the present invention may be characterized by a low dielectric constant (Dk). Thus, in one embodiment, the dielectric constant (Dk) of the cured product of the resin composition when measured at 5.8 GHz and 23°C as in Test Example 1 below may be preferably 5.0 or less, more preferably 4.5 or less, even more preferably 4.0 or less, even more preferably 3.7 or less, and particularly preferably 3.5 or less, 3.4 or less.

<Resin sheet>
The resin composition of the present invention can be used by coating in the form of a varnish, but from an industrial perspective, it is generally preferred to use the resin composition in the form of a resin sheet containing the resin composition.

The resin sheet of the present invention is a resin sheet for forming an interlayer insulating layer of a printed wiring board (a resin sheet for forming an interlayer insulating layer of a printed wiring board).

In one embodiment, the resin sheet has a support and a resin composition layer provided on the support, and the resin composition layer is formed from the resin composition described above.

The thickness of the resin composition layer is preferably 50 μm or less, more preferably 40 μm or less, from the viewpoint of making the printed wiring board thinner and being able to provide a cured product with excellent insulating properties even if the cured product of the resin composition is a thin film. The lower limit of the thickness of the resin composition layer is not particularly limited, but can usually be 5 μm or more, 10 μm or more, etc.

Examples of the support include films made of plastic materials, metal foils, and release paper, with films made of plastic materials and metal foils being preferred.

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

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, a foil made of a single metal, copper, or an alloy of copper and another metal (e.g., tin, chromium, silver, magnesium, nickel, zirconium, silicon, titanium, etc.) may be used.

The support may be subjected to a matte treatment, corona treatment, or antistatic treatment on the surface that is to be bonded to the resin composition layer.

As the support, a support with a release layer having a release layer on the surface to be bonded to the resin composition layer may be used. Examples of the release agent used in the release layer of the support with a release layer include one or more release agents selected from the group consisting of alkyd resins, polyolefin resins, urethane resins, and silicone resins. The support with a release layer may be a commercially available product, such as "SK-1", "AL-5", and "AL-7" manufactured by Lintec Corporation, "Lumirror T60" manufactured by Toray Industries, "Purex" manufactured by Teijin Limited, and "Unipeel" manufactured by Unitika Limited, which are PET films having a release layer mainly composed of an alkyd resin-based release agent.

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

In one embodiment, the resin sheet may further include an optional layer as necessary. Examples of such optional layers include a protective film similar to the support provided on the surface of the resin composition layer that is not bonded to the support (i.e., the surface opposite the support). The thickness of the protective film is not particularly limited, but is, for example, 1 μm to 40 μm. By laminating the protective film, it is possible to suppress adhesion of dirt and the like and scratches on the surface of the resin composition layer.

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

The organic solvent may be the same as the organic solvent described as a component of the resin composition. The organic solvent may be used alone or in combination of two or more kinds.

Drying may be performed by known methods such as heating or blowing hot air. There are no particular limitations on the drying conditions, but drying is performed so that the content of organic solvent in the resin composition layer is 10% by mass or less, preferably 5% by mass or less. Although it varies depending on the boiling point of the organic solvent in the resin composition or resin varnish, for example, when using a resin composition or resin varnish containing 30% by mass to 60% by mass of organic solvent, the resin composition layer can be formed by drying at 50°C to 150°C for 3 to 10 minutes.

The resin sheet can be stored in a roll. If the resin sheet has a protective film, it can be used by peeling off the protective film.

<Printed Wiring Board>
The printed wiring board of the present invention includes an insulating layer made of a cured product obtained by curing the resin composition of the present invention.

The printed wiring board can be produced, for example, by using the above-mentioned resin sheet by a method including the following steps (I) and (II).
(I) a step of laminating a resin sheet on an inner layer substrate so that a resin composition layer of the resin sheet is bonded to the inner layer substrate; and (II) a step of curing (e.g., thermally curing) the resin composition layer to form an insulating layer.

The "inner layer substrate" used in step (I) is a member that will be the substrate of the printed wiring board, and examples thereof include glass epoxy substrates, metal 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 the conductor layer may be patterned. An inner layer substrate having a conductor layer (circuit) formed on one or both sides of the substrate may be called an "inner layer circuit substrate." In addition, intermediate products on which an insulating layer and/or a conductor layer is to be formed during the manufacture of a printed wiring board are also included in the "inner layer substrate" of the present invention. When the printed wiring board is a component-embedded circuit board, an inner layer substrate with a component embedded may be used.

The inner layer substrate and the resin sheet can be laminated, for example, by heat-pressing the resin sheet to the inner layer substrate from the support side. Examples of the member for heat-pressing the resin sheet to the inner layer substrate (hereinafter also referred to as the "heat-pressing member") include a heated metal plate (such as a SUS panel) or a metal roll (SUS roll). Note that rather than pressing the heat-pressing 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 follow the surface irregularities of the inner layer substrate.

The lamination of the inner layer substrate and the resin sheet may be performed by a vacuum lamination method. In the vacuum lamination method, the heat-pressure bonding temperature is preferably in the range of 60°C to 160°C, more preferably in the range of 80°C to 140°C, the heat-pressure bonding pressure is preferably in the range of 0.098MPa to 1.77MPa, more preferably in the range of 0.29MPa to 1.47MPa, and the heat-pressure bonding time is preferably in the range of 20 seconds to 400 seconds, more preferably in the range of 30 seconds to 300 seconds. The lamination may be performed under reduced pressure conditions, preferably at a pressure of 26.7hPa or less.

Lamination can be performed using a commercially available 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.

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

The support may be removed between steps (I) and (II), or after step (II).

In step (II), the resin composition layer is cured (e.g., thermally cured) to form an insulating layer made of a cured product of the resin composition. The curing conditions for the resin composition layer are not particularly limited, and conditions that are typically used when forming an insulating layer for a printed wiring board may be used.

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

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

When manufacturing a printed wiring board, the steps of (III) drilling holes in the insulating layer, (IV) roughening the insulating layer, and (V) forming a conductor layer may be further carried out. These steps (III) to (V) may be carried out according to various methods known to those skilled in the art that are used in the manufacture of printed wiring boards. When the support is removed after step (II), the removal of the support may be carried out between steps (II) and (III), between steps (III) and (IV), or between steps (IV) and (V). Furthermore, the formation of the insulating layer and the conductor layer in steps (II) to (V) may be repeated as necessary to form a multilayer wiring board.

In another embodiment, the printed wiring board of the present invention can be manufactured using the above-mentioned prepreg. The manufacturing method is basically the same as when a resin sheet is used.

Step (III) is a step of drilling holes in the insulating layer, which allows holes such as via holes and through holes to be formed in the insulating layer. Step (III) may be performed using, for example, a drill, a laser, plasma, etc., depending on the composition of the resin composition used to form the insulating layer. The dimensions and shape of the holes may be appropriately determined depending on the design of the printed wiring board.

Step (IV) is a step of roughening the insulating layer. Usually, smears are also removed in this step (IV). The procedure and conditions of the roughening treatment are not particularly limited, and known procedures and conditions that are usually used when forming an insulating layer of a printed wiring board can be adopted. For example, the insulating layer can be roughened by carrying out a swelling treatment with a swelling liquid, a roughening treatment with an oxidizing agent, and a neutralization treatment with a neutralizing liquid in this order.

The swelling liquid used in the roughening treatment is not particularly limited, but includes an alkaline solution, a surfactant solution, etc., and is preferably an alkaline solution, and more preferably a sodium hydroxide solution or a potassium hydroxide solution. Examples of commercially available swelling liquids include "Swelling Dip Securigans P" and "Swelling Dip Securigans SBU" manufactured by Atotech Japan. The swelling treatment using the swelling liquid is not particularly limited, but can be performed by immersing the insulating layer in a swelling liquid at 30°C to 90°C for 1 to 20 minutes, for example. From the viewpoint of suppressing the swelling of the resin of the insulating layer to an appropriate level, it is preferable to immerse the insulating layer in a swelling liquid at 40°C to 80°C for 5 to 15 minutes.

The oxidizing agent used in the roughening treatment is not particularly limited, but examples thereof include an alkaline permanganate solution in which potassium permanganate or sodium permanganate is dissolved in an aqueous solution of sodium hydroxide. The roughening treatment using an oxidizing agent such as an alkaline permanganate solution is preferably performed by immersing the insulating layer in an oxidizing agent solution heated to 60°C to 100°C for 10 to 30 minutes. The concentration of permanganate in the alkaline permanganate solution is preferably 5% by mass to 10% by mass. Examples of commercially available oxidizing agents include alkaline permanganate solutions such as "Concentrate Compact CP" and "Dosing Solution Securigans P" manufactured by Atotech Japan.

The neutralizing solution used in the roughening treatment is preferably an acidic aqueous solution, and a commercially available product such as "Reduction Solution Securigant P" manufactured by Atotech Japan is an example.

Treatment with a neutralizing solution can be carried out by immersing the surface that has been roughened with an oxidizing agent in a neutralizing solution at 30°C to 80°C for 5 to 30 minutes. From the standpoint of workability, etc., it is preferable to immerse the object that has been roughened with an oxidizing agent in a neutralizing solution at 40°C to 70°C for 5 to 20 minutes.

In one embodiment, the arithmetic mean roughness (Ra) of the insulating layer surface after the roughening treatment is not particularly limited, but is preferably 500 nm or less, more preferably 400 nm or less, and even more preferably 300 nm or less. The lower limit is not particularly limited, and may be, for example, 1 nm or more, 2 nm or more, etc. The root mean square roughness (Rq) of the insulating layer surface after the roughening treatment is preferably 500 nm or less, more preferably 400 nm or less, and even more preferably 300 nm or less. The lower limit is not particularly limited, and may be, for example, 1 nm or more, 2 nm or more, etc. The arithmetic mean roughness (Ra) and root mean square roughness (Rq) of the insulating layer surface can be measured using a non-contact surface roughness meter.

Step (V) is a step of forming a conductor layer, and the conductor layer is formed on the insulating layer. The conductor material used for the conductor layer is not particularly limited. In a preferred embodiment, the conductor layer contains one or more metals selected from the group consisting of gold, platinum, palladium, silver, copper, aluminum, cobalt, chromium, zinc, nickel, titanium, tungsten, iron, tin and indium. The conductor layer may be a single metal layer or an alloy layer, and examples of the alloy layer include layers formed from alloys of two or more metals selected from the above group (e.g., nickel-chromium alloy, copper-nickel alloy and copper-titanium alloy). Among these, from the viewpoints of versatility in forming the conductor layer, cost, ease of patterning, etc., a single metal layer of chromium, nickel, titanium, aluminum, zinc, gold, palladium, silver, or copper, or an alloy layer of a nickel-chromium alloy, a copper-nickel alloy, or a copper-titanium alloy is preferred, a single metal layer of chromium, nickel, titanium, aluminum, zinc, gold, palladium, silver, or copper, or an alloy layer of a nickel-chromium alloy is more preferred, and a single metal layer of copper is even more preferred.

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

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

In one embodiment, the conductor layer may be formed by plating. For example, a conductor layer having a desired wiring pattern can be formed by plating the surface of the insulating layer using a conventionally known technique such as a semi-additive method or a full-additive method, and from the viewpoint of ease of manufacture, it is preferable to form the conductor layer by a semi-additive method. An example of forming a conductor layer by a semi-additive method is shown below.

First, a plating seed layer is formed on the surface of the insulating layer by electroless plating. Next, a mask pattern is formed on the formed plating seed layer to expose a portion of the plating seed layer corresponding to the desired wiring pattern. A metal layer is formed on the exposed plating seed layer by electrolytic plating, and the mask pattern is then removed. Thereafter, unnecessary plating seed layer is removed by etching or the like, and a conductor layer having the desired wiring pattern can be formed.

In another embodiment, the conductor layer may be formed using a metal foil. When the conductor layer is formed using a metal foil, it is preferable to perform step (V) between steps (I) and (II). For example, after step (I), the support is removed, and a metal foil is laminated on the exposed surface of the resin composition layer. The lamination of the resin composition layer and the metal foil may be performed by a vacuum lamination method. The lamination conditions may be the same as those described for step (I). Next, step (II) is performed to form an insulating layer. Thereafter, a conductor layer having a desired wiring pattern can be formed by a conventionally known technique such as a subtractive method or a modified semi-additive method using the metal foil on the insulating layer.

Metal foils can be manufactured by known methods such as electrolysis and rolling. Commercially available metal foils include HLP foil and JXUT-III foil manufactured by JX Nippon Mining & Metals Corporation, and 3EC-III foil and TP-III foil manufactured by Mitsui Mining & Smelting Co., Ltd.

<Semiconductor Device>
The semiconductor device of the present invention includes the printed wiring board of the present invention. The semiconductor device of the present invention can be manufactured using the printed wiring board of the present invention.

Semiconductor devices include various semiconductor devices used in electrical appliances (e.g., computers, mobile phones, digital cameras, and televisions) and vehicles (e.g., motorcycles, automobiles, trains, ships, and aircraft).

The present invention will be specifically described 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. In the following description, the temperature conditions are normal temperature (25°C) unless otherwise specified, and the pressure conditions are normal pressure (1 atm) unless otherwise specified.

Synthesis Example 1: Synthesis of epoxy resin A
95 parts of 2,6-xylenol and 6.3 parts of 47% _BF3 ether complex were charged into a reaction apparatus consisting of a glass separable flask equipped with a stirrer, a thermometer, a nitrogen blowing tube, a dropping funnel, and a cooling tube, and heated to 70°C while stirring. While maintaining the temperature, 58.8 parts of dicyclopentadiene (0.56 times the moles relative to 2,6-xylenol) were added dropwise over 1 hour. After reacting for 3 hours at a temperature of 115 to 125°C, 69.2 parts of dicyclopentadiene (0.67 times the moles relative to 2,6-xylenol) were added dropwise over 1 hour at the same temperature, and reacted for 2 hours at a temperature of 115 to 125°C. 1.0 part of calcium hydroxide was added, and 2.0 parts of a 10% aqueous oxalic acid solution were further added. Thereafter, the mixture was heated to 160°C for dehydration, and heated to 200°C under a reduced pressure of 5 mmHg to remove unreacted raw materials by evaporation. 520 parts of MIBK was added thereto to dissolve the product, and 150 parts of 80°C hot water was added for washing, and the lower aqueous layer was separated and removed. Thereafter, the mixture was heated to 160°C under a reduced pressure of 5 mmHg to evaporate and remove the MIBK, yielding 221 parts of reddish brown phenolic resin A. The hydroxyl equivalent was 377, the softening point was 102°C, and the absorption ratio ( _A3040 / _A1210 ) was 0.18.

180 parts of phenolic resin A, 221 parts of epichlorohydrin, and 33 parts of diethylene glycol dimethyl ether were added to a reaction apparatus equipped with a stirrer, a thermometer, a nitrogen blowing tube, a dropping funnel, and a cooling tube, and the mixture was heated to 65°C. 39 parts of 49% aqueous sodium hydroxide solution were added dropwise over 4 hours while maintaining the temperature at 63-67°C under a reduced pressure of 125 mmHg. During this time, epichlorohydrin was azeotroped with water, and the water that flowed out was sequentially removed from the system. After the reaction was completed, epichlorohydrin was recovered under conditions of 5 mmHg and 180°C, and 482 parts of MIBK were added to dissolve the product. Then, 146 parts of water were added to dissolve the by-product salt, and the mixture was left to stand, and the salt water in the lower layer was separated and removed. After neutralization with an aqueous phosphoric acid solution, the resin solution was washed with water until the washings became neutral, and then filtered. The mixture was heated to 180°C under a reduced pressure of 5 mmHg to remove the MIBK, yielding 200 parts of a reddish-brown transparent 2,6-xylenol-dicyclopentadiene type epoxy resin (epoxy resin A). The resin had an epoxy equivalent of 446 g/eq., a total chlorine content of 431 ppm, and a softening point of 91°C.

<Example 1: Preparation of resin composition 1>
20 parts of the epoxy resin A (epoxy equivalent: 446 g/eq.) synthesized in Synthesis Example 1, 5 parts of a bisphenol-based epoxy resin ("ZX-1059" manufactured by Nippon Steel Chemical & Material Co., Ltd., epoxy equivalent: about 165 g/eq.), and 5 parts of a biphenylaralkyl-type epoxy resin ("YX4000HK" manufactured by Mitsubishi Chemical Corporation, epoxy equivalent: 194 g/eq.) were heated and dissolved with stirring in 30 parts of solvent naphtha and 10 parts of cyclohexanone. This produced an epoxy resin solution.

After cooling to room temperature, 150 parts of an inorganic filler (spherical silica "SO-C2" manufactured by Admatechs and surface-treated with N-phenyl-8-aminooctyltrimethoxysilane manufactured by Shin-Etsu Chemical Co., Ltd., specific surface area: 5.8 m ² /g, average particle size: 0.5 μm), 32 parts of an active ester-based curing agent ("HPC-8150-62T" manufactured by DIC Corporation, active group equivalent of about 229 g/eq., toluene solution with solid content of 62% by mass), 5 parts of a phenol-based curing agent ("LA-3018-50P" manufactured by DIC Corporation, active group equivalent of about 151 g/eq., 2-methoxypropanol solution with solid content of 50%), and a thermoplastic resin ("YX7553B A varnish-like resin composition 1 was prepared by mixing 17 parts of a curing accelerator (4-dimethylaminopyridine (DMAP), a 1:1 solution of MEK and cyclohexanone with a solid content of 30% by mass, manufactured by Mitsubishi Chemical Corporation, and 0.6 parts of a curing accelerator (4-dimethylaminopyridine (DMAP), a MEK solution with a solid content of 5% by mass). The mixture was uniformly dispersed using a high-speed rotary mixer, and then filtered using a cartridge filter ("SHP020", manufactured by ROKITECHNO CORPORATION).

<Example 2: Preparation of resin composition 2>
In Example 1, 32 parts of an active ester curing agent (DIC Corporation's "HPC-8150-62T", active group equivalent of about 229 g/eq., toluene solution with solid content of 62% by mass) was replaced with 31 parts of an active ester curing agent (DIC Corporation's "HPC-8000-65T", active group equivalent of about 223 g/eq., toluene solution with solid content of 65% by mass). A varnish-like resin composition 2 was prepared in the same manner as in Example 1, except for the above points.

<Comparative Example 1: Preparation of Resin Composition 3>
In Example 1, 20 parts of bisphenol AF type epoxy resin ("NC-3000", manufactured by Nippon Kayaku Co., Ltd., epoxy equivalent: about 275 g/eq.) was used in place of 20 parts of epoxy resin A (epoxy equivalent: 446 g/eq.). A varnish-like resin composition 3 was prepared in the same manner as in Example 1 except for the above.

<Comparative Example 2: Preparation of Resin Composition 4>
In Example 1, 20 parts of a naphthol aralkyl type epoxy resin ("ESN-475V" manufactured by Nippon Steel Chemical & Material Co., Ltd., epoxy equivalent: about 330 g/eq.) was used in place of 20 parts of the epoxy resin A (epoxy equivalent: 446 g/eq.). A varnish-like resin composition 4 was prepared in the same manner as in Example 1 except for the above.

Comparative Example 3: Preparation of Resin Composition 5
In Comparative Example 2, 31 parts of an active ester curing agent ("HPC-8000-65T" manufactured by DIC Corporation, active group equivalent of about 223 g/eq., toluene solution with solid content of 65% by mass) was used instead of 32 parts of an active ester curing agent ("HPC-8150-62T" manufactured by DIC Corporation, active group equivalent of about 229 g/eq., toluene solution with solid content of 62% by mass). A varnish-like resin composition 5 was prepared in the same manner as in Comparative Example 2 except for the above points.

<Preparation Example 1: Preparation of resin sheet>
As a support, a PET film ("Lumirror R80" manufactured by Toray Industries, Inc., thickness 38 μm, softening point 130° C., hereinafter sometimes referred to as "release PET") that had been release-treated with an alkyd resin-based release agent ("AL-5" manufactured by Lintec Corporation) was prepared.

The resin compositions prepared in the examples and comparative examples were uniformly applied to a release PET sheet using a die coater so that the thickness of the resin composition layer after drying was 25 μm, and the sheet was dried at 80°C for 1 minute to form a resin composition layer on the release PET sheet. Next, a rough surface of a polypropylene film (Oji F-Tex Co., Ltd. "Alphan MA-411", thickness 15 μm) was laminated as a protective film on the surface of the resin composition layer not bonded to the support, so as to be bonded to the resin composition layer. This produced a resin sheet consisting of the release PET (support), the resin composition layer, and the protective film in that order.

<Test Example 1: Measurement and Evaluation of Dielectric Constant and Dielectric Tangent>
The protective film was peeled off from the resin sheet prepared in Preparation Example 1, and the resin composition layer was thermally cured by heating at 200°C for 90 minutes, and then the support was peeled off. The obtained cured product was cut into a test piece having a width of 2 mm and a length of 80 mm. The relative dielectric constant (Dk) and dielectric loss tangent (Df) of the test piece were measured at a measurement frequency of 5.8 GHz and a measurement temperature of 23°C by a cavity resonance perturbation method using an "HP8362B" manufactured by Agilent Technologies. Measurements were performed on three test pieces, the average value was calculated, and the average value was evaluated according to the following evaluation criteria.

Evaluation criteria: "Good": When the relative dielectric constant (Dk) is 3.5 or less and the dielectric dissipation factor (Df) is 0.0040 or less; "Poor": When the relative dielectric constant (Dk) is more than 3.5 or the dielectric dissipation factor (Df) is more than 0.0040.

<Test Example 2: Evaluation of smear removal ability>
(1) Surface treatment of the interior substrate A glass cloth-based epoxy resin double-sided copper-clad laminate (copper foil thickness 18 μm, substrate thickness 0.8 mm, Panasonic "R1515A") having copper foil on the surface was prepared as the inner layer substrate. The copper foil on the surface of this inner layer substrate was etched with a microetching agent (Mech "CZ8101") with a copper etching amount of 1 μm to perform a roughening treatment. Then, it was dried at 190° C. for 30 minutes.

(2) Lamination and curing of resin sheet The resin sheet prepared in Preparation Example 1 was laminated on both sides of the inner layer substrate using a batch type vacuum pressure laminator (two-stage build-up laminator "CVP700" manufactured by Nikko Materials Co., Ltd.) so that the resin composition layer was bonded to the inner layer substrate. This lamination was performed by reducing the pressure for 30 seconds to 13 hPa or less, and then pressing at a temperature of 100 ° C and a pressure of 0.74 MPa for 30 seconds. Next, the laminated resin sheet was heat pressed at atmospheric pressure, 100 ° C, and a pressure of 0.5 MPa for 60 seconds to be smoothed. Further, this was placed in an oven at 100 ° C and heated for 30 minutes, and then transferred to an oven at 170 ° C and heated for 30 minutes. This formed an insulating layer formed of a cured product of the resin composition.

(3) Via hole formation:
Using a _CO2 laser processing machine (LK-2K212/2C) manufactured by Via Mechanics, the insulating layer on one side of the inner layer substrate was processed under the conditions of a frequency of 2000 Hz, a pulse width of 3 μs, an output of 0.95 W, and a shot number of 3, to form a via hole with a top diameter (diameter) of 50 μm on the insulating layer surface and a diameter of 50 μm on the insulating layer bottom surface. After that, the support was peeled off to obtain a circuit substrate.

(4) Roughening Treatment The insulating layer surface of the circuit board was immersed in a swelling liquid, Swelling Dip Securigant P, manufactured by Atotech Japan, for 10 minutes at 60° C. Next, the insulating layer surface of the circuit board was immersed in a roughening liquid, Concentrate Compact P (aqueous solution of KMnO ₄ : 60 g/L, NaOH: 40 g/L), manufactured by Atotech Japan, for 25 minutes at 80° C. Finally, the insulating layer surface of the circuit board was immersed in a neutralizing liquid, Reduction Solution Securigant P, manufactured by Atotech Japan, for 5 minutes at 40° C.

(5) Evaluation of Residue at Bottom of Via Hole The periphery of the bottom of three via holes was observed with a scanning electron microscope (SEM), and the maximum smear length from the wall surface of the bottom of the via hole was measured from the obtained image and evaluated according to the following evaluation criteria.

Evaluation criteria: "◯": Maximum smear length is less than 5 μm (i.e., none of the three via holes has a smear length of 5 μm or more, and smear removal is good).
"X": The maximum smear length is 5 μm or more (i.e., at least one of the three via holes has a smear length of 5 μm or more, and the smear removal performance is poor)

<Test Example 3: Measurement and Evaluation of Elongation at Break>
Brittleness was evaluated by measuring the elongation at break according to the following procedure: A tensile test was carried out on the cured product A for evaluation in accordance with Japanese Industrial Standard JIS K7127 using a Tensilon universal testing machine ("RTC-1250A" manufactured by Orientec Co., Ltd.) to measure the elongation at break (%) and evaluate it according to the following evaluation criteria.

Evaluation criteria: "◯": Elongation at break is 1.0% or more; "×": Elongation at break is less than 1.0%

The non-volatile component contents of the resin compositions of the examples and comparative examples, as well as the measurement results and evaluation results of the test examples, are shown in Table 1 below.

As shown in Table 1, by using a resin composition containing (A) an epoxy resin, (B) an active ester compound, and (C) an inorganic filler, in which component (A) contains the specific epoxy resin (A-1) described above, it is possible to obtain a cured product with a low dielectric tangent and excellent smear removal properties and elongation at break.

Claims (16)

A resin composition comprising (A) an epoxy resin, (B) an active ester compound, and (C) an inorganic filler,
The component (A) is represented by formula (A-1) (1):

[Wherein,
R ¹ is each independently a hydrogen atom, a group represented by formula (1a), or a group represented by formula (1b), and at least one R ¹ is a group represented by formula (1a) or a group represented by formula (1b):

(In formulas (1a) and (1b), * indicates a binding site.)
R ² and R ³ each independently represent a hydrocarbon group having 1 to 8 carbon atoms;
n is an integer of 0 or more and indicates the number of repeating units.
The epoxy resin is represented by the formula:
the content of the component (A-1) relative to the component (A) is 30% by mass or more and 80% by mass or less, and the mass ratio of the component (B) to the component (A) (component (B)/component (A)) is 0.1 or more and 3 or less,
A resin composition for forming an interlayer insulating layer of a printed wiring board, the resin composition having a cured product with an elongation at break of 1.0% or more when measured at 23°C in accordance with JIS K7127. The resin composition for forming an interlayer insulating layer of a printed wiring board according to claim 1, wherein the average value of n is within the range of 0 to 5. The resin composition for forming an interlayer insulating layer of a printed wiring board according to claim 1 or 2, wherein component (A) further contains an epoxy resin that is liquid at a temperature of 20°C. The resin composition for forming an interlayer insulating layer of a printed wiring board according to any one of claims 1 to 3, wherein the content of component (A) is 1% by mass to 30% by mass, assuming that the non-volatile components in the resin composition are 100% by mass. The resin composition for forming an interlayer insulating layer of a printed wiring board according to any one of claims 1 to 4, wherein the content of component (B) is 5% by mass or more, assuming that the non-volatile components in the resin composition are 100% by mass. The resin composition for forming an interlayer insulating layer of a printed wiring board according to any one of claims 1 to 5, wherein component (C) is silica. The resin composition for forming an interlayer insulating layer of a printed wiring board according to any one of claims 1 to 6, wherein the content of component (C) is 40% by mass or more, assuming that the non-volatile components in the resin composition are 100% by mass. The resin composition for forming an interlayer insulating layer of a printed wiring board according to any one of claims 1 to 7, further comprising a phenoxy resin. The resin composition for forming an interlayer insulating layer of a printed wiring board according to any one of claims 1 to 8, further comprising a phenol-based curing agent. The resin composition for forming an interlayer insulating layer of a printed wiring board according to any one of claims 1 to 9, wherein the dielectric loss tangent (Df) of the cured product of the resin composition is 0.0040 or less when measured at 5.8 GHz and 23°C. The resin composition for forming an interlayer insulating layer of a printed wiring board according to any one of claims 1 to 10, wherein the relative dielectric constant (Dk) of the cured product of the resin composition is 3.5 or less when measured at 5.8 GHz and 23°C. A resin sheet having a support and a resin composition layer provided on the support,
the resin composition layer contains (A) an epoxy resin, (B) an active ester compound, and (C) an inorganic filler;
The component (A) is represented by formula (A-1) (1):

[Wherein,
R ¹ is each independently a hydrogen atom, a group represented by formula (1a), or a group represented by formula (1b), and at least one R ¹ is a group represented by formula (1a) or a group represented by formula (1b):

(In formulas (1a) and (1b), * indicates a binding site.)
R ² and R ³ each independently represent a hydrocarbon group having 1 to 8 carbon atoms;
n is an integer of 0 or more and indicates the number of repeating units.
A resin composition layer formed of a resin composition containing an epoxy resin represented by the formula:
A resin sheet (excluding prepregs) for forming an interlayer insulating layer of a printed wiring board, wherein a resin composition layer which is a cured product of the resin composition has an elongation at break of 1.0% or more when measured at 23°C in accordance with JIS K7127 . The resin composition has a content of the component (A-1) relative to the component (A) of 30% by mass or more and 80% by mass or less, and a mass ratio of the component (B) to the component (A) (component (B)/component (A)) is 0.1 to 3. The resin sheet for forming an interlayer insulating layer of a printed wiring board according to claim 12 . A resin composition comprising (A) an epoxy resin, (B) an active ester compound, and (C) an inorganic filler,
The component (A) is represented by formula (A-1) (1):

[Wherein,
R ¹ is each independently a hydrogen atom, a group represented by formula (1a), or a group represented by formula (1b), and at least one R ¹ is a group represented by formula (1a) or a group represented by formula (1b):

(In formulas (1a) and (1b), * indicates a binding site.)
R ² and R ³ each independently represent a hydrocarbon group having 1 to 8 carbon atoms;
n is an integer of 0 or more and indicates the number of repeating units.
The present invention provides an insulating layer made of a cured product of a resin composition (excluding prepregs) containing an epoxy resin represented by the formula:
The printed wiring board has a breaking elongation of 1.0% or more when the cured product of the resin composition is measured at 23°C in accordance with JIS K7127. The resin composition has a content of the (A-1) component relative to the (A) component of 30% by mass or more and 80% by mass or less, and a mass ratio of the (B) component to the (A) component ((B) component/(A) component) is 0.1 to 3. The printed wiring board according to claim 14 . A semiconductor device comprising the printed wiring board according to claim 14 or 15 .