Resin composition

Abstract

To provide a resin composition capable of obtaining an insulating layer capable of reducing a dielectric loss tangent and suppressing warpage.SOLUTION: A resin composition contains (A) an epoxy resin, (B) a curing agent, (C) a low-elasticity polymer, and (D) an inorganic filler, in which (B) the curing agent contains (B-1) an active ester resin containing one or more skeletons selected from the group consisting of an aliphatic hydrocarbon skeleton having 4 or more carbon atoms, a polyalkyleneoxy skeleton, a polysiloxane skeleton, and a polycarbonate skeleton.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a resin composition, a cured product thereof, a resin sheet, a circuit board, and a semiconductor device. [Background technology]

[0002] Circuit boards such as printed wiring boards are widely used in various electronic devices. A known method for manufacturing circuit boards is a build-up method in which insulating layers and conductor layers are alternately stacked on an inner layer substrate. The insulating layer is formed, for example, from a cured product of a resin composition. Specifically, a resin composition layer containing a resin composition is formed, and then cured to form an insulating layer containing a cured product of the resin composition. Known examples of such resin compositions include resin compositions containing an epoxy resin, a curing agent, and an inorganic filler (Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2022-100697 [Patent Document 2] Japanese Patent Publication No. 2023-037522 Summary of the Invention [Problem to be solved by the invention]

[0004] Insulating layers of circuit boards are required to have a low dielectric loss tangent to suppress transmission loss. To achieve this, active ester resins are sometimes used as curing agents. However, when conventional resin compositions using curing agents containing active ester resins are used, the warping of the circuit board tends to increase.

[0005] The present invention has been made in view of the above-mentioned problems, and aims to provide a resin composition capable of obtaining an insulating layer that can reduce the dielectric tangent and suppress warpage; a resin sheet containing the resin composition; a cured product of the resin composition; a circuit board containing the cured product of the resin composition; and a semiconductor device including the circuit board. [Means for solving the problem]

[0006] The present inventors have conducted extensive research to solve the above-mentioned problems. Generally, to enable an epoxy resin and an activated ester resin to react, the ester bond of the activated ester resin is required to be bonded to an aromatic ring. The present inventors have found that one of the causes of warpage in conventional activated ester resins is that they have a rigid molecular structure with an aromatic ring skeleton. Based on this finding, the present inventors have conducted further research and found that a resin composition containing an epoxy resin, a curing agent including an activated ester resin having a specific skeleton, a low-elasticity polymer, and an inorganic filler can solve the above-mentioned problems, thereby completing the present invention. That is, the present invention includes the following:

[0007] <1> (A) an epoxy resin, (B) a curing agent, (C) a low modulus polymer, and (D) an inorganic filler; (B) A resin composition, wherein the curing agent comprises (B-1) an active ester resin containing one or more skeletons selected from the group consisting of an aliphatic hydrocarbon skeleton having 4 or more carbon atoms, a polyalkyleneoxy skeleton, a polysiloxane skeleton, and a polycarbonate skeleton. <2> The component (B-1) contains an aryloxycarbonyl group which may have a methyl group or a hydroxy group. <1> The resin composition according to claim 1. <3> (C) the low elastic polymer comprises one or more selected from the group consisting of a polybutadiene structure, a polycarbonate structure, a polyalkylene structure, a polyalkyleneoxy structure, a polysiloxane structure, a poly(meth)acrylate structure, a polyisoprene structure, a polyisobutylene structure, and a polystyrene structure; <1> or <2> The resin composition according to claim 1. <4> (D) The amount of the inorganic filler is 50% by mass or more relative to 100% by mass of the nonvolatile components of the resin composition. <1> ~ <3> The resin composition according to any one of claims 1 to 10. <5> (D) the low modulus polymer has a weight average molecular weight greater than 5,000; <1> ~ <4> The resin composition according to any one of claims 1 to 10. <6> For forming an insulating layer, <1> ~ <5> The resin composition according to any one of claims 1 to 10. <7> A support and a resin composition layer provided on the support, The resin composition layer is <1> ~ <6> A resin sheet comprising the resin composition according to any one of claims 1 to 4. <8> <1> ~ <6> A cured product of the resin composition according to any one of claims 1 to 4. <9> <1> ~ <6> A circuit board comprising a cured product of the resin composition according to any one of claims 1 to 4. <10> <9> A semiconductor device comprising the circuit board according to claim 1. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a resin composition capable of obtaining an insulating layer that can reduce the dielectric tangent and suppress warpage; a resin sheet containing the resin composition; a cured product of the resin composition; a circuit board containing the cured product of the resin composition; and a semiconductor device including the circuit board. DETAILED DESCRIPTION OF THE INVENTION

[0009] The present invention will be described below with reference to embodiments and examples. However, the present invention is not limited to the embodiments and examples shown below, and may be modified and implemented within the scope of the claims and their equivalents.

[0010] As used herein, the term "optionally substituted" in reference to a compound or group means both a case where the hydrogen atoms of the compound or group are not substituted with substituents, and a case where some or all of the hydrogen atoms of the compound or group are substituted with substituents.

[0011] <Outline of Resin Composition> A resin composition according to one embodiment of the present invention includes (A) an epoxy resin, (B) a curing agent, (C) a low-elasticity polymer, and (D) an inorganic filler. The (B) curing agent includes (B-1) an activated ester resin containing one or more skeletons selected from the group consisting of an aliphatic hydrocarbon skeleton having 4 or more carbon atoms, a polyalkyleneoxy skeleton, a polysiloxane skeleton, and a polycarbonate skeleton. The "one or more skeletons selected from the group consisting of an aliphatic hydrocarbon skeleton having 4 or more carbon atoms, a polyalkyleneoxy skeleton, a polysiloxane skeleton, and a polycarbonate skeleton" are typically flexible molecular skeletons, and are therefore sometimes referred to as "flexible skeletons" below. Furthermore, the "(B-1) activated ester resin containing one or more skeletons selected from the group consisting of an aliphatic hydrocarbon skeleton having 4 or more carbon atoms, a polyalkyleneoxy skeleton, a polysiloxane skeleton, and a polycarbonate skeleton" containing the flexible skeleton is sometimes referred to as "(B-1) flexible activated ester resin."

[0012] The resin composition according to the present embodiment can provide an insulating layer that can reduce the dielectric loss tangent and suppress warpage. In addition, the insulating layer obtained from the resin composition according to the present embodiment can usually have excellent chemical resistance. The inventors of the present invention speculate that the mechanism by which such excellent effects are obtained is as follows: However, the technical scope of the present invention is not limited to the mechanism below.

[0013] The resin composition according to this embodiment contains (A) an epoxy resin and (B) a curing agent containing (B-1) a flexible active ester resin. Therefore, the resin composition is cured by the reaction between (A) the epoxy resin and (B-1) the flexible active ester resin, resulting in a cured product. Generally, the reaction between the epoxy groups contained in (A) the epoxy resin and the active ester groups contained in (B-1) the flexible active ester resin does not produce polar groups such as hydroxyl groups. Therefore, the resulting cured product has low polarity. Therefore, by forming an insulating layer using this cured product, an insulating layer with a low dielectric loss tangent can be obtained.

[0014] The resin composition according to this embodiment also contains an inorganic filler (D). Generally, inorganic fillers (D) have a lower coefficient of linear thermal expansion than organic materials. Therefore, the cured product of the resin composition containing the inorganic filler (D) also has a low coefficient of linear thermal expansion. Furthermore, the resin composition according to this embodiment contains a flexible active ester resin (B-1) and a low-elasticity polymer (C) with flexible molecular skeletons. These flexible active ester resin (B-1) and low-elasticity polymer (C) can absorb stress when stress occurs in the cured product. Therefore, the cured product of the resin composition according to this embodiment can suppress deformation due to stress. Thus, the cured product of the resin composition according to this embodiment has a low coefficient of linear thermal expansion, so heat-induced stress generation is small. Even if stress does occur, deformation can be suppressed by the action of the flexible active ester resin (B-1) and the low-elasticity polymer (C). Therefore, by forming an insulating layer using the cured product, an insulating layer capable of suppressing warpage can be obtained.

[0015] Generally, when an epoxy group reacts with an activated ester group, an ester bond is formed. However, this ester bond is usually prone to decomposition in alkaline aqueous solutions. Therefore, conventional resin compositions combining an epoxy resin and an activated ester resin have difficulty obtaining cured products with high resistance to chemicals such as alkaline aqueous solutions. In contrast, the flexible activated ester resin (B-1) used in this embodiment contains a flexible backbone, which results in a longer molecular chain per activated ester group than conventional activated ester resins. Therefore, the density of ester bonds formed by the reaction between the epoxy resin and the activated ester resin is lower in the cured product. This reduces the density of bonds that are easily decomposed in alkaline aqueous solutions, allowing the cured product to have high resistance to alkaline aqueous solutions. Furthermore, the flexible backbone, particularly the "aliphatic hydrocarbon backbone having 4 or more carbon atoms," can enhance the hydrophobicity of the flexible activated ester resin (B-1), thereby enhancing the hydrophobicity of the cured product, thereby significantly improving resistance to alkaline aqueous solutions.

[0016] <(A) Epoxy resin> The resin composition according to the present embodiment includes an epoxy resin (A) as component (A). The epoxy resin (A) may be a curable resin having an epoxy group. The epoxy resin (A) may be used alone or in combination of two or more types.

[0017] Examples of (A) epoxy resins include bisphenol A type epoxy resins, bisphenol F type epoxy resins, bisphenol S type epoxy resins, bisphenol AF type epoxy resins, dicyclopentadiene type epoxy resins, trisphenol type epoxy resins, naphthol novolac type epoxy resins, phenol novolac type epoxy resins, tert-butyl-catechol type epoxy resins, naphthalene type epoxy resins, naphthol type epoxy resins, anthracene type epoxy resins, glycidylamine type epoxy resins, glycidyl ester type epoxy resins, cresol novolac type epoxy resins, 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, and phenolphthalimidine type epoxy resins. Biphenyl-type epoxy resin refers to an epoxy resin having a biphenyl structure, where the biphenyl structure may have a substituent such as an alkyl group, an alkoxy group, an aryl group, etc. Therefore, bixylenol-type epoxy resins and biphenylaralkyl-type epoxy resins may also be included in the biphenyl-type epoxy resins.

[0018] From the viewpoint of obtaining a cured product having excellent heat resistance, the (A) epoxy resin preferably contains an epoxy resin having an aromatic structure. The aromatic structure is a chemical structure generally defined as aromatic, and also includes polycyclic aromatic rings and aromatic heterocycles. Examples of epoxy resins containing an aromatic structure include 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, bisxyleneol type epoxy resins, glycidylamine type epoxy resins having an aromatic structure, glycidyl ester type epoxy resins having an aromatic structure, cresol novolac type epoxy resins, biphenyl type epoxy resins, linear aliphatic epoxy resins having an aromatic structure, epoxy resins having a butadiene structure having an aromatic structure, alicyclic epoxy resins having an aromatic structure, heterocyclic epoxy resins, spiro ring-containing epoxy resins having an aromatic structure, cyclohexanedimethanol type epoxy resins having an aromatic structure, naphthylene ether type epoxy resins, trimethylol type epoxy resins having an aromatic structure, and tetraphenylethane type epoxy resins having an aromatic structure.

[0019] Among these, bisphenol A type epoxy resins, bisphenol F type epoxy resins, naphthalene type epoxy resins, and biphenyl type epoxy resins are preferred; bisphenol A type epoxy resins, bisphenol F type epoxy resins, naphthalene type epoxy resins, bixylenol type epoxy resins, and biphenyl aralkyl type epoxy resins are more preferred.

[0020] The (A) epoxy resin preferably contains an epoxy resin having two or more epoxy groups per molecule, and the proportion of the epoxy resin having two or more epoxy groups per molecule relative to 100% by mass of the non-volatile components of the (A) epoxy resin is preferably 50% by mass or more, more preferably 60% by mass or more, and even more preferably 70% by mass or more.

[0021] (A) 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 resins may contain only liquid epoxy resins, only solid epoxy resins, or a combination of liquid epoxy resins and solid epoxy resins.

[0022] The liquid epoxy resin is preferably a liquid epoxy resin having two or more epoxy groups in one molecule, such as bisphenol A epoxy resin, bisphenol F epoxy resin, bisphenol AF epoxy resin, naphthalene epoxy resin, glycidyl ester epoxy resin, glycidyl amine epoxy resin, phenol novolac epoxy resin, alicyclic epoxy resin having an ester skeleton, cyclohexane epoxy resin, cyclohexanedimethanol epoxy resin, and epoxy resin having a butadiene structure; more preferably bisphenol A epoxy resin, bisphenol F epoxy resin, and naphthalene epoxy resin.

[0023] Specific examples of liquid epoxy resins include "HP-4032," "HP-4032-D," and "HP-4032-SS" (naphthalene-type epoxy resins) manufactured by DIC Corporation; "828US," "828EL," "jER828EL," "825," and "Epikote 828EL" (bisphenol A-type epoxy resins) manufactured by Mitsubishi Chemical Corporation; "jER807" and "1750" (bisphenol F-type epoxy resins) manufactured by Mitsubishi Chemical Corporation; "jER152" (phenol novolac-type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "630," "630LSD," and "604" (glycidylamine-type epoxy resins) manufactured by Mitsubishi Chemical Corporation; "ED-523T" (glycirol-type epoxy resin) manufactured by ADEKA Corporation; and "EP-3950L" and "EP-398" manufactured by ADEKA Corporation. 0S" (glycidylamine type epoxy resin); ADEKA's "EP-4088S" (dicyclopentadiene type epoxy resin); Nippon Steel Chemical & Material's "ZX1059" (a mixture of bisphenol A type epoxy resin and bisphenol F type epoxy resin); Nagase ChemteX's "EX-721" (glycidyl ester type epoxy resin); Daicel's "Celloxide 2021P" (alicyclic epoxy resin with an ester skeleton); Daicel's "PB-3600," Nippon Soda's "JP-100" and "JP-200" (epoxy resins with a butadiene structure); and Nippon Steel Chemical & Material's "ZX1658" and "ZX1658GS" (liquid 1,4-glycidylcyclohexane type epoxy resin).

[0024] The solid epoxy resin is preferably a solid epoxy resin having three or more epoxy groups per molecule, more preferably an aromatic solid epoxy resin having three or more epoxy groups per molecule. Examples of the solid epoxy resin include 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; biphenyl-type epoxy resins are more preferred; bixylenol-type epoxy resins and biphenyl aralkyl-type epoxy resins are even more preferred.

[0025] Specific examples of solid epoxy resins include DIC Corporation's "HP4032H" (naphthalene-type epoxy resin); DIC Corporation's "HP-4700" and "HP-4710" (naphthalene-type tetrafunctional epoxy resins); DIC Corporation's "N-690" (cresol novolac-type epoxy resin); DIC Corporation's "N-695" (cresol novolac-type epoxy resin); DIC Corporation's "HP-7200," "HP-7200HH," "HP-7200H," and "HP-7200L" (dicyclopentadiene-type epoxy resins); and DIC Corporation'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 Kayaku Co., Ltd.; "ESN475V", "ESN4" manufactured by Nippon Steel Chemical & Material Co., Ltd. 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 Corporation; "YL6121" (biphenyl-type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "YX8800" (anthracene-type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "Y" manufactured by Mitsubishi Chemical Corporation Examples include "X7700" (phenol aralkyl type epoxy resin); "PG-100" and "CG-500" manufactured by Osaka Gas Chemicals Co., Ltd.; "YX7760" (bisphenol AF type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "YL7800" (fluorene type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "jER1010" (bisphenol A type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "jER1031S" (tetraphenylethane type epoxy resin) manufactured by Mitsubishi Chemical Corporation; and "WHR991S" (phenolphthalimidine type epoxy resin) manufactured by Nippon Kayaku Co., Ltd.

[0026] When the (A) epoxy resin contains a combination of a liquid epoxy resin and a solid epoxy resin, the mass ratio thereof (liquid epoxy resin:solid epoxy resin) is preferably 20:1 to 1:20, more preferably 10:1 to 1:10, and particularly preferably 7:1 to 1:7.

[0027] The epoxy equivalent of the (A) epoxy resin is preferably in the range of 50 g / eq to 5,000 g / eq, more preferably 60 g / eq to 3,000 g / eq, even more preferably 80 g / eq to 2,000 g / eq, and particularly preferably 110 g / eq to 1,000 g / eq. The epoxy equivalent represents the mass of the resin per equivalent of epoxy groups. This epoxy equivalent can be measured according to JIS K7236.

[0028] The weight average molecular weight (Mw) of the (A) epoxy resin is preferably in the range of 100 to 5,000, more preferably 250 to 3,000, and even more preferably 400 to 1,500. The weight average molecular weight can be measured by gel permeation chromatography (GPC) as a polystyrene-equivalent value.

[0029] The amount of (A) epoxy resin is preferably 0.1% by mass or more, more preferably 1% by mass or more, and even more preferably 2% by mass or more, relative to 100% by mass of the nonvolatile components in the resin composition. The nonvolatile components in the resin composition refer to all components in the resin composition excluding the solvent, unless otherwise specified. When the amount of (A) epoxy resin is within the above range, the dielectric loss tangent and warpage can be effectively reduced, and typically, chemical resistance can be effectively improved.

[0030] The amount of (A) epoxy resin is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 20% by mass or more, relative to 100% by mass of the resin components in the resin composition. It is preferably 60% by mass or less, more preferably 50% by mass or less, and particularly preferably 40% by mass or less. Unless otherwise specified, the resin components in the resin composition refer to all nonvolatile components in the resin composition excluding the (D) inorganic filler. When the amount of (A) epoxy resin is within the above range, the dielectric loss tangent and warpage can be effectively reduced, and typically, chemical resistance can be effectively improved.

[0031] <(B) Hardener> The resin composition according to this embodiment includes a (B) curing agent as component (B). The (B) curing agent reacts with the (A) epoxy resin to form a bond, thereby curing the resin composition. The (B) curing agent does not include those corresponding to the above-mentioned component (A). One type of (B) curing agent may be used alone, or two or more types may be used in combination.

[0032] The (B) curing agent contains a (B-1) flexible active ester resin as the component (B-1). The (B-1) flexible active ester resin refers to an active ester resin containing one or more flexible skeletons selected from the group consisting of an aliphatic hydrocarbon skeleton having 4 or more carbon atoms, a polyalkyleneoxy skeleton, a polysiloxane skeleton, and a polycarbonate skeleton. Therefore, the (B-1) flexible active ester resin can be a curable resin containing a combination of an active ester group and the flexible skeleton. One type of (B-1) flexible active ester resin may be used alone, or two or more types may be used in combination.

[0033] The activated ester group refers to a group formed by an ester bond directly bonded to an aromatic ring. This activated ester group encompasses not only ester bonds contained in an aromatic carbon-C(═O)-O-aromatic carbon structure, but also ester bonds contained in an aliphatic carbon-C(═O)-O-aromatic carbon structure, as long as they can react with an epoxy group to form a bond. The term "aromatic ring" refers to a ring conforming to Hückel's rule, in which the number of electrons contained in the π electron system of the ring is 4p+2 (p is a natural number), and includes monocyclic aromatic rings and fused polycyclic aromatic rings in which two or more monocyclic aromatic rings are fused. The aromatic ring may be an aromatic carbocycle containing only carbon atoms as ring-constituting atoms, or an aromatic heterocycle containing heteroatoms such as oxygen, nitrogen, or sulfur atoms as ring-constituting atoms in addition to carbon atoms. Aromatic rings are preferred, with benzene, naphthalene, and anthracene rings being more preferred, and benzene and naphthalene rings being even more preferred. The term "aromatic carbon" refers to the carbon atoms constituting an aromatic ring.

[0034] The number of active ester groups contained in one molecule of the (B-1) flexible active ester resin is usually 1 or more, preferably 2 or more, and may be 2. When the (B-1) flexible active ester resin contains two or more active ester groups in one molecule, it is preferable that a flexible skeleton is contained in part or all of the structure linking the active ester groups.

[0035] The flexible skeleton is selected from the group consisting of an aliphatic hydrocarbon skeleton having 4 or more carbon atoms, a polyalkyleneoxy skeleton, a polysiloxane skeleton, and a polycarbonate skeleton. The (B-1) flexible active ester resin may contain one flexible skeleton alone or a combination of two or more flexible skeletons.

[0036] The number of carbon atoms in an "aliphatic hydrocarbon skeleton having 4 or more carbon atoms" is usually 4 or more, preferably 6 or more, and may be 8 or more or 10 or more. The upper limit may be, for example, 20 or less, 18 or less, or 16 or less. The aliphatic hydrocarbon skeleton refers to the carbon skeleton of an aliphatic hydrocarbon group. The aliphatic hydrocarbon skeleton may be a saturated aliphatic hydrocarbon skeleton containing only saturated carbon-carbon bonds, or an unsaturated aliphatic hydrocarbon skeleton containing unsaturated carbon-carbon bonds such as carbon-carbon double bonds and carbon-carbon triple bonds. Such aliphatic hydrocarbon skeletons are more flexible than aromatic hydrocarbon skeletons, and can exhibit high flexibility, particularly when the number of carbon atoms is large as described above. The carbon atoms contained in the aliphatic hydrocarbon skeleton may be bonded to a hydrogen atom or a substituent. Examples of substituents that may be bonded to carbon atoms of the aliphatic hydrocarbon skeleton include: halogen atoms; aromatic hydrocarbon groups such as aryl groups; hydrocarbonoxy groups such as alkoxy groups, cycloalkyloxy groups, and aryloxy groups; hydrocarbonoxycarbonyl groups such as alkyloxycarbonyl groups, cycloalkyloxycarbonyl groups, and aryloxycarbonyl groups; and the like.

[0037] A "polyalkyleneoxy skeleton" refers to a skeleton containing two or more alkyleneoxy groups. The number of carbon atoms in the alkyleneoxy group is usually one or more, preferably two or more, and may be four or more, six or more, etc. The upper limit may be, for example, 20 or less, 18 or less, or 16 or less, etc. Since the polyalkyleneoxy skeleton contains two or more alkyleneoxy groups, it can be a flexible skeleton.

[0038] The term "polysiloxane skeleton" refers to a skeleton containing two or more siloxane bonds (-O-Si-). Generally, siloxane bonds are flexible bonds, and therefore a polysiloxane skeleton containing a plurality of such siloxane bonds can be flexible. The silicon atoms contained in the polysiloxane skeleton may be bonded to hydrogen atoms or organic groups such as hydrocarbon groups.

[0039] A "polycarbonate skeleton" refers to a skeleton containing two or more carbonate bonds (-O-C(=O)-O-). A polycarbonate skeleton may contain a hydrocarbon skeleton between the two or more carbonate bonds. Since the ether bonds (-O-) contained in the carbonate bonds are flexible, a polycarbonate skeleton containing a plurality of carbonate bonds can be flexible.

[0040] Among the flexible skeletons, an "aliphatic hydrocarbon skeleton having 4 or more carbon atoms" is preferred from the viewpoint of effectively reducing the dielectric loss tangent and warpage, and effectively improving chemical resistance. This aliphatic hydrocarbon skeleton may be contained in a hydrocarbon group which may have a substituent. For example, the (B-1) flexible active ester resin may contain a monovalent or divalent or higher hydrocarbon group which may have a substituent, and the hydrocarbon group may contain an aliphatic hydrocarbon skeleton.

[0041] Examples of hydrocarbon groups containing an "aliphatic hydrocarbon skeleton having 4 or more carbon atoms" include divalent aliphatic hydrocarbon groups having 4 or more carbon atoms, which may have a substituent. The number of carbon atoms in this aliphatic hydrocarbon group is usually 4 or more, preferably 6 or more, and may be 8 or more or 10 or more. The upper limit may be, for example, 20 or less, 18 or less, or 16 or less. This divalent aliphatic hydrocarbon group may be a saturated aliphatic hydrocarbon group or an unsaturated aliphatic hydrocarbon group. Furthermore, this divalent aliphatic hydrocarbon group may be linear, branched, or cyclic, with linear or branched being preferred. Examples of the substituent include the same examples as those of the substituents that may be bonded to carbon atoms in the aliphatic hydrocarbon skeleton.

[0042] Specific examples of the optionally substituted divalent aliphatic hydrocarbon group having 4 or more carbon atoms include divalent groups represented by any of the following formulas (b1-1) to (b1-4).

[0043] [ka]

[0044] (In formulas (b1-1) to (b1-4), R 1 , R 2 , R 3 and R 4 each independently represents a hydrogen atom, a halogen atom, or an alkyl group having 1 to 6 carbon atoms, preferably a hydrogen atom or an alkyl group, more preferably a hydrogen atom or a methyl group; R 5 represents a monovalent hydrocarbon group, preferably an alkyl group or an aryl group; n1 usually represents an integer of 1 or more, preferably 2 or more, and preferably 10 or less, more preferably 9 or less, and even more preferably 8 or less; n2 usually represents an integer of 1 or more, preferably 2 or more, and preferably 10 or less, more preferably 9 or less, and even more preferably 8 or less; n3 usually represents an integer of 4 or more, preferably 6 or more, more preferably 8 or more, and also preferably 20 or less, more preferably 18 or less, and even more preferably 16 or less; n4 usually represents an integer of 2 or more, preferably 3 or more, more preferably 4 or more, and also preferably 10 or less, more preferably 9 or less, and even more preferably 8 or less; * represents a bonding site.

[0045] The (B-1) flexible activated ester resin may contain an aryloxycarbonyl group which may have a substituent. The (B-1) flexible activated ester resin may have this aryloxycarbonyl group at the end of the molecule of the (B-1) flexible activated ester resin. From the viewpoint of effectively reducing the dielectric tangent and warpage and effectively improving chemical resistance, the substituent which the aryloxycarbonyl group may have is preferably an alkyl group or a hydroxy group, more preferably a methyl group or a hydroxy group. Therefore, the (B-1) flexible activated ester resin more preferably contains an aryloxycarbonyl group which may have a methyl group or a hydroxy group. The oxycarbonyl group contained in these aryloxycarbonyl groups may form an active ester group of the (B-1) flexible activated ester resin. Specific examples of the aryloxycarbonyl group which may have a substituent include groups of the following formulas (b2-1) to (b2-10). In formulas (b2-1) to (b2-10), * represents a bonding site.

[0046] [ka]

[0047] A preferred example of the (B-1) soft active ester resin is an active ester resin represented by the following formula (B-1).

[0048] [ka]

[0049] (In formula (B-1), B 1 each independently represents an aromatic ring; B 2 each independently represents an aromatic ring which may have a substituent; R 6 each independently represents a divalent group containing the flexible skeleton described above; R 7 each independently represents a substituent; each n5 independently represents 0 or an integer of 1 or more; and n6 represents a number of 1 or more.

[0050] In formula (B-1), B 1 each independently represents an aromatic ring. 1 is preferably an aromatic carbon ring, more preferably a benzene ring or a naphthalene ring, and even more preferably a benzene ring.

[0051] In formula (B-1), B 2 B each independently represents an aromatic ring which may have a substituent. 2 is preferably an aromatic carbocyclic ring which may have a substituent, more preferably an aromatic carbocyclic ring which has no substituent, and further preferably an unsubstituted benzene ring or naphthalene ring.

[0052] In formula (B-1), R 6 R each independently represents a divalent group containing a flexible skeleton. 6 R is preferably a divalent group containing the above-mentioned divalent aliphatic hydrocarbon group having 4 or more carbon atoms which may have a substituent; R may also be a divalent aliphatic hydrocarbon group having 4 or more carbon atoms which may have a substituent. 6 is preferably a divalent hydrocarbon group containing a divalent group represented by any one of the above formulas (b1-1) to (b1-3).

[0053] In formula (B-1), R 7 each independently represents a substituent. Examples of the substituent include alkyl groups such as methyl, ethyl, propyl, and butyl; and hydroxy groups. Of these, methyl and hydroxy groups are preferred.

[0054] In formula (B-1), n5 each independently represents an integer of 0 or greater than 1. n5 is preferably an integer of 0 to 5, more preferably an integer of 0 to 4, and even more preferably 0 or 1.

[0055] In formula (B-1), n6 represents the average number of repetitions and is a number equal to or greater than 1. n6 is usually equal to or greater than 1, preferably equal to or greater than 2, and is preferably equal to or less than 20, more preferably equal to or less than 10.

[0056] Specific examples of the (B-1) soft activated ester resin include activated ester resins represented by the following formulas (b-1) to (b-6).

[0057] [ka]

[0058] (In formulas (b-1) to (b-6), n7 to n 11 and n 13 represents the same meaning as n6 in formula (B-1). 12 represents a number greater than 0, preferably a number greater than or equal to 1.)

[0059] The (B-1) flexible active ester resin may be produced, for example, by the method described in JP 2022-100697 A or JP 2023-037522 A. A commercially available product may also be used as the (B-1) flexible active ester resin. For example, the resin of formula (b-6) is available as "EXB-LE-P01" manufactured by DIC Corporation.

[0060] The active ester group equivalent range of the (B-1) flexible active ester resin is preferably 200 g / eq or more, more preferably 250 g / eq or more, particularly preferably 300 g / eq or more, and is preferably 3,000 g / eq or less, more preferably 2,000 g / eq or less, and even more preferably 1,500 g / eq or less. The active ester group equivalent represents the mass of the resin per equivalent of the active ester group.

[0061] The weight average molecular weight (Mw) of the (B-1) soft active ester resin is preferably in the range of 500 or more, more preferably 1,000 or more, and preferably 10,000 or less, more preferably 5,000 or less, and even more preferably 3,000 or less.

[0062] The number of active ester groups in the (B-1) flexible active ester resin is preferably 0.01 or more, more preferably 0.02 or more, even more preferably 0.05 or more, and preferably 1 or less, more preferably 0.5 or less, even more preferably 0.3 or less, relative to the number of epoxy groups in the (A) epoxy resin, where 1 is the number of epoxy groups in the (A) epoxy resin. The "number of epoxy groups in the (A) epoxy resin" in a resin composition refers to the sum of all values ​​obtained by dividing the mass of the non-volatile components of the (A) epoxy resin present in the resin composition by its epoxy equivalent. Furthermore, the "number of active ester groups in the (B-1) flexible active ester resin" in a resin composition refers to the sum of all values ​​obtained by dividing the mass of the non-volatile components of the (B-1) flexible active ester resin present in the resin composition by its active ester group equivalent. When the number of active ester groups in the (B-1) flexible active ester resin is within the above range, the dielectric loss tangent and warpage can be effectively reduced, and typically, chemical resistance can be effectively improved.

[0063] The amount of the (B-1) flexible active ester resin is preferably 0.1% by mass or more, more preferably 1% by mass or more, even more preferably 1.5% by mass or more, and 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, relative to 100% by mass of the nonvolatile components in the resin composition. When the amount of the (B-1) flexible active ester resin is within the above range, the dielectric loss tangent and warpage can be effectively reduced, and usually chemical resistance can also be effectively improved.

[0064] The amount of the (B-1) flexible active ester resin is preferably 1% by mass or more, more preferably 3% by mass or more, and even more preferably 5% by mass or more, relative to 100% by mass of the resin components in the resin composition, and is preferably 30% by mass or less, more preferably 20% by mass or less, and particularly preferably 12% by mass or less. When the amount of the (B-1) flexible active ester resin is within the above range, the dielectric loss tangent and warpage can be effectively reduced, and usually chemical resistance can also be effectively improved.

[0065] The amount of the (B-1) flexible active ester resin is preferably 10% by mass or more, more preferably 20% by mass or more, particularly preferably 30% by mass or more, and is preferably 80% by mass or less, more preferably 60% by mass or less, and even more preferably 50% by mass or less, relative to 100% by mass of the total amount of the (B) curing agent in the resin composition. When the amount of the (B-1) flexible active ester resin is within the above range, the dielectric loss tangent and warpage can be effectively reduced, and usually chemical resistance can also be effectively improved.

[0066] The mass ratio of the (B-1) flexible active ester resin to the (C) low-elasticity polymer ((B-1) flexible active ester / (C) low-elasticity polymer) is preferably 0.10 or more, more preferably 0.15 or more, even more preferably 0.20 or more, and is preferably 2.0 or less, more preferably 1.5 or less, and particularly preferably 1.0 or less. When the amount of the (B-1) flexible active ester resin is within the above range, the dielectric loss tangent and warpage can be effectively reduced, and usually, chemical resistance can also be effectively improved.

[0067] The (B) curing agent may contain (B-2) an optional curing agent other than the (B-1) flexible active ester resin. Examples of the (B-2) optional curing agent include any active ester resin other than the (B-1) flexible active ester resin, a phenolic resin, a carbodiimide resin, a cyanate resin, a benzoxazine resin, an acid anhydride resin, an amine resin, and a thiol resin. The (B-2) optional curing agent may be used alone or in combination of two or more. Among these, any active ester resin, a phenolic resin, a carbodiimide resin, and a cyanate resin are preferred.

[0068] The optional active ester resin may be a resin having one or more, preferably two or more, active ester groups in one molecule. Among them, the optional active ester resin is preferably a resin having two or more highly reactive ester groups in one molecule, such as phenol esters, thiophenol esters, N-hydroxyamine esters, or esters of heterocyclic hydroxy compounds.

[0069] The optional active ester resin is preferably one obtained by a condensation reaction between a carboxylic acid compound and / or a thiocarboxylic acid compound and a hydroxy compound and / or a thiol compound. From the viewpoint of improving heat resistance in particular, an active ester resin obtained from a carboxylic acid compound and a hydroxy compound is preferred, and an active ester resin 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, resorcinol, bisphenol A, bisphenol F, bisphenol S, phenolphthalene, methylated bisphenol A, methylated bisphenol F, methylated bisphenol S, phenol, o-cresol, m-cresol, p-cresol, catechol, α-naphthol, β-naphthol, 1,5-dihydroxynaphthalene, 1,6-dihydroxynaphthalene, 2,6-dihydroxynaphthalene, dihydroxybenzophenone, trihydroxybenzophenone, tetrahydroxybenzophenone, phloroglucin, benzenetriol, dicyclopentadiene-type diphenol compounds, and phenol novolak. Here, "dicyclopentadiene-type diphenol compounds" refers to diphenol compounds obtained by condensing one dicyclopentadiene molecule with two phenol molecules.

[0070] Specifically, the optional active ester resin is preferably a dicyclopentadiene-type active ester resin, a naphthalene-type active ester resin containing a naphthalene structure, an active ester resin containing an acetylated product of phenol novolac, or an active ester resin containing a benzoylated product of phenol novolac, and among these, a naphthalene-type active ester resin is more preferred. As the dicyclopentadiene-type active ester resin, an active ester resin containing a dicyclopentadiene-type diphenol structure is preferred.

[0071] Commercially available active ester resins include, for example, active ester resins containing a dicyclopentadiene-type diphenol structure such as "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); and active ester resins containing a naphthalene structure such as "HP-B-8151-62T", "EXB-8100L-65T", "EXB-8150-60T", and "EXB-8150- 62T," "EXB-9416-70BK," "HPC-8150-60T," "HPC-8150-62T," and "HPC-8151-62T" (manufactured by DIC Corporation); a phosphorus-containing activated ester resin such as "EXB9401" (manufactured by DIC Corporation); an activated ester resin which is an acetylated product of phenol novolac such as "DC808" (manufactured by Mitsubishi Chemical Corporation); activated ester resins which are benzoylated products of phenol novolac such as "YLH1026," "YLH1030," and "YLH1048" (manufactured by Mitsubishi Chemical Corporation); and an activated ester resin containing a styryl group and a naphthalene structure such as "PC1300-02-65MA" (manufactured by Air Water Inc.).

[0072] As the phenolic resin, a resin having one or more, preferably two or more, hydroxyl groups (phenolic hydroxyl groups) bonded to an aromatic ring such as a benzene ring or a naphthalene ring per molecule can be used. From the viewpoint of heat resistance and water resistance, a phenolic resin having a novolac structure is preferred. From the viewpoint of adhesion, a nitrogen-containing phenolic resin is preferred, and a triazine skeleton-containing phenolic resin is more preferred. Among these, a triazine skeleton-containing phenolic novolac resin is preferred from the viewpoint of highly satisfying heat resistance, water resistance, and adhesion.

[0073] Specific examples of phenolic resins include "MEH-7700", "MEH-7810", "MEH-7851", and "MEH-8000H" manufactured by Meiwa Kasei Co., Ltd.; "NHN", "CBN", and "GPH" manufactured by Nippon Kayaku Co., Ltd.; and "SN-170", "SN-180", "SN-190", "SN-475", "SN-485", "SN-495", "SN-495V", and "SN- 375" and "SN-395" manufactured by DIC Corporation; "TD-2090", "TD-2090-60M", "LA-7052", "LA-7054", "LA-1356", "LA-3018", "LA-3018-50P", "LA-1356", "TD2090", and "TD-2090-60M" manufactured by DIC Corporation; and "GDP-6115L", "GDP-6115H", and "ELPC75" manufactured by Gun-ei Chemical Co., Ltd.

[0074] As the carbodiimide resin, a resin having one or more, preferably two or more, carbodiimide structures in one molecule can be used. Specific examples of the carbodiimide resin include aliphatic biscarbodiimides such as tetramethylene-bis(t-butylcarbodiimide) and cyclohexanebis(methylene-t-butylcarbodiimide); aromatic biscarbodiimides such as phenylene-bis(xylylcarbodiimide); aliphatic polycarbodiimides such as polyhexamethylenecarbodiimide, polytrimethylhexamethylenecarbodiimide, polycyclohexylenecarbodiimide, poly(methylenebiscyclohexylenecarbodiimide), and poly(isophoronecarbodiimide); poly(phenylenecarbodiimide), poly(naphthalenecarbodiimide); Examples of polycarbodiimides include aromatic polycarbodiimides such as poly(methylenediphenylenecarbodiimide), 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 resins include, for example, "Carbodilite V-02B," "Carbodilite V-03," "Carbodilite V-04K," "Carbodilite V-05," "Carbodilite V-07," and "Carbodilite V-09" manufactured by Nisshinbo Chemical Inc.; and "Stavaxol P," "Stavaxol P400," and "Hykasil 510" manufactured by Lanxess AG.

[0075] As the cyanate-based resin, a resin having one or more, preferably two or more, cyanate groups in one molecule can be used. Examples of cyanate resins include bifunctional cyanate resins such as bisphenol A dicyanate, polyphenol cyanate, oligo(3-methylene-1,5-phenylene cyanate), 4,4'-methylenebis(2,6-dimethylphenyl cyanate), 4,4'-ethylidene diphenyl dicyanate, hexafluorobisphenol A dicyanate, 2,2-bis(4-cyanate)phenylpropane, 1,1-bis(4-cyanatephenylmethane), bis(4-cyanate-3,5-dimethylphenyl)methane, 1,3-bis(4-cyanatephenyl-1-(methylethylidene))benzene, bis(4-cyanatephenyl)thioether, and bis(4-cyanatephenyl)ether; multifunctional cyanate resins derived from phenol novolac, cresol novolac, and the like; and prepolymers in which these cyanate resins are partially triazine converted. Specific examples of cyanate-based resins include "PT30" and "PT60" (phenol novolac-type multifunctional cyanate-based resins) manufactured by Lonza, "BA230" and "BA230S75" (prepolymers in which part or all of bisphenol A dicyanate has been triazine-converted to form a trimer).

[0076] The benzoxazine resin may be a resin having one or more, preferably two or more, benzoxazine rings in one molecule. Specific examples of the benzoxazine resin include "JBZ-OP100D" and "ODA-BOZ" manufactured by JFE Chemical Corporation, "HFB2006M" manufactured by Showa Polymer Co., Ltd., and "Pd", "Fa", and "ALP-d" manufactured by Shikoku Chemicals Corporation.

[0077] As the acid anhydride resin, a resin having one or more, preferably two or more, acid anhydride groups in one molecule can be used. Specific examples of the acid anhydride resin include phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, methylnadic anhydride, hydrogenated methylnadic anhydride, trialkyltetrahydrophthalic anhydride, dodecenyl succinic anhydride, 5-(2,5-dioxotetrahydro-3-furanyl)-3-methyl-3-cyclohexene-1,2-dicarboxylic anhydride, trimellitic anhydride, pyromellitic anhydride, and benzophenonetetracarboxylic dianhydride. Examples of suitable anhydrides include anhydrides, biphenyltetracarboxylic dianhydride, naphthalenetetracarboxylic dianhydride, oxydiphthalic dianhydride, 3,3'-4,4'-diphenylsulfonetetracarboxylic dianhydride, 1,3,3a,4,5,9b-hexahydro-5-(tetrahydro-2,5-dioxo-3-furanyl)-naphtho[1,2-C]furan-1,3-dione, ethylene glycol bis(anhydrotrimellitate), and polymeric anhydrides such as styrene-maleic acid resins, which are copolymers of styrene and maleic acid. Commercially available acid anhydride resins include, for example, "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" manufactured by Resonac Corporation; and "EF-30," "EF-40," "EF-60," and "EF-80" manufactured by Cray Valley Chemical Industries, Ltd.

[0078] The amine resin may be a resin having one or more, preferably two or more, amino groups in one molecule. Examples of the amine resin include aliphatic amines, polyether amines, alicyclic amines, and aromatic amines, with aromatic amines being preferred. The amine resin is preferably a primary amine or secondary amine, with primary amines being more preferred. Specific examples of the amine resin include 4,4'-methylenebis(2,6-dimethylaniline), 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenyl sulfone, 3,3'-diaminodiphenyl sulfone, m-phenylenediamine, m-xylylenediamine, diethyltoluenediamine, 4,4'-diaminodiphenyl ether, 3,3'-dimethyl-4,4'-diaminobiphenyl, 2,2'-dimethyl-4,4'-diaminobiphenyl, 3,3'-dihydroxybenzidine, and 2,2-bis(3-amino-4-hydroxyphenyl)propanol. Examples of suitable bis(4-aminophenoxy)benzene include bis(4-aminophenyl)propane, 3,3-dimethyl-5,5-diethyl-4,4-diphenylmethanediamine, 2,2-bis(4-aminophenyl)propane, 2,2-bis(4-(4-aminophenoxy)phenyl)propane, 1,3-bis(3-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, 1,4-bis(4-aminophenoxy)benzene, 4,4'-bis(4-aminophenoxy)biphenyl, bis(4-(4-aminophenoxy)phenyl)sulfone, and bis(4-(3-aminophenoxy)phenyl)sulfone. Commercially available amine-based resins include, for example, "SEIKACURE-S" manufactured by Seika Corporation; "KAYABOND C-200S," "KAYABOND C-100," "KAYAHARD AA," "KAYAHARD AB," and "KAYAHARD AS" manufactured by Nippon Kayaku Co., Ltd.; "Epicure W" manufactured by Mitsubishi Chemical Corporation; and "DTDA" manufactured by Sumitomo Seika Chemicals Co., Ltd.

[0079] Examples of thiol-based resins include trimethylolpropane tris(3-mercaptopropionate), pentaerythritol tetrakis(3-mercaptobutyrate), and tris(3-mercaptopropyl)isocyanurate.

[0080] The active group equivalent of the optional curing agent (B-2) is preferably 50 g / eq to 3,000 g / eq, more preferably 100 g / eq to 1,000 g / eq, even more preferably 100 g / eq to 500 g / eq, and particularly preferably 100 g / eq to 300 g / eq. The active group equivalent represents the mass of the resin per equivalent of the active group. For example, the active group equivalent of a phenolic resin represents the phenolic hydroxyl group equivalent, which represents the mass of the resin per equivalent of the phenolic hydroxyl group.

[0081] The range of the weight average molecular weight (Mw) of the optional curing agent (B-2) may be the same as the range of the weight average molecular weight (Mw) of the epoxy resin (A).

[0082] The amount of optional curing agent (B-2) is preferably 0.1% by mass or more, more preferably 1% by mass or more, and even more preferably 2% by mass or more, relative to 100% by mass of nonvolatile components in the resin composition, and is preferably 30% by mass or less, more preferably 20% by mass or less, and even more preferably 10% by mass or less. When the amount of optional curing agent (B-2) is within this range, the dielectric loss tangent and warpage can be effectively reduced, and usually chemical resistance can also be effectively improved.

[0083] The amount of optional curing agent (B-2) is preferably 1% by mass or more, more preferably 5% by mass or more, and even more preferably 10% by mass or more, relative to 100% by mass of the resin components in the resin composition, and is preferably 50% by mass or less, more preferably 40% by mass or less, and even more preferably 30% by mass or less. When the amount of optional curing agent (B-2) is within the above range, the dielectric loss tangent and warpage can be effectively reduced, and usually chemical resistance can also be effectively improved.

[0084] The number of active groups in the (B) curing agent, assuming the number of epoxy groups in the (A) epoxy resin to be 1, is preferably 0.1 or more, more preferably 0.3 or more, even more preferably 0.5 or more, and is preferably 3 or less, more preferably 2 or less, and particularly preferably 1 or less. The "number of active groups in the (B) curing agent" in the resin composition refers to the total value obtained by dividing the mass of the non-volatile components of the (B) curing agent present in the resin composition by its active group equivalent. When the number of active groups in the (B) curing agent is within the above range, the dielectric loss tangent and warpage can be effectively reduced, and further, chemical resistance can usually be effectively improved.

[0085] The amount of (B) curing agent is preferably 1% by mass or more, more preferably 2% by mass or more, even more preferably 3% by mass or more, and is preferably 40% by mass or less, more preferably 30% by mass or less, even more preferably 20% by mass or less, and particularly preferably 10% by mass or less, relative to 100% by mass of nonvolatile components in the resin composition. When the amount of (B) curing agent is within the above range, the dielectric loss tangent and warpage can be effectively reduced, and usually chemical resistance can also be effectively improved.

[0086] The amount of (B) curing agent is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 15% by mass or more, relative to 100% by mass of the resin component in the resin composition, and is preferably 60% by mass or less, more preferably 50% by mass or less, and particularly preferably 40% by mass or less. When the amount of (B) curing agent is within the above range, the dielectric loss tangent and warpage can be effectively reduced, and usually, chemical resistance can also be effectively improved.

[0087] <(C) Low Elasticity Polymer> The resin composition according to this embodiment includes a (C) low-elasticity polymer as the (C) component. The (C) low-elasticity polymer is a polymer having a low elastic modulus. Typically, the (C) low-elasticity polymer is included in the resin composition in a state where it is compatible with the resin components such as the (A) and (B) components, and is included in the cured product while maintaining this compatible state. The (C) low-elasticity polymer does not include those corresponding to the above-mentioned (A) and (B) components. One type of (C) low-elasticity polymer may be used alone, or two or more types may be used in combination.

[0088] (C) low-elasticity polymers typically have a low modulus of elasticity. Specifically, when a tensile test is conducted in accordance with Japanese Industrial Standards (JIS K7161) at a temperature of 25°C and a humidity of 40% RH, (C) low-elasticity polymers typically exhibit a modulus of elasticity of 1 GPa or less. Specifically, the range of the modulus of elasticity of (C) low-elasticity polymers is typically 1 GPa or less, preferably 0.9 GPa or less, more preferably 0.8 GPa or less, even more preferably 0.7 GPa or less, and preferably 0.01 GPa or more, more preferably 0.03 GPa or more, even more preferably 0.05 GPa or more, and particularly preferably 0.1 GPa or more.

[0089] Since (C) the low elastic polymer is a polymer, it usually has a large weight-average molecular weight. The weight-average molecular weight Mw of (C) the low elastic polymer is preferably greater than 5,000, more preferably 8,000 or more, and even more preferably 10,000 or more. The upper limit is preferably 1,000,000 or less, more preferably 500,000 or less, even more preferably 200,000 or less, even more preferably 100,000 or less, even more preferably 50,000 or less, and even more preferably 30,000 or less.

[0090] As the (C) low-elasticity polymer, a resin containing one or more structures selected from the group consisting of a polybutadiene structure, a polycarbonate structure, a polyalkylene structure, a polyalkyleneoxy structure, a polysiloxane structure, a poly(meth)acrylate structure, a polyisoprene structure, a polyisobutylene structure, and a polystyrene structure within the molecule is preferred. The term "(meth)acrylate" encompasses acrylates, methacrylates, and combinations thereof. These structures may be contained in the main chain or in the side chain. These structures typically have little restriction on atomic movement due to the interatomic bonds contained in the structure, allowing for a wide range of bond angle changes and rotations, and therefore can function as a flexible molecular skeleton. Therefore, a (C) low-elasticity polymer can be easily obtained from a resin containing such a structure. Among these, a resin containing one or more structures selected from the group consisting of a polybutadiene structure, a polycarbonate structure, and a polyalkylene structure is more preferred.

[0091] A resin containing a polybutadiene structure is sometimes referred to as a "polybutadiene resin." The polybutadiene structure may be partially or completely hydrogenated. Examples of polybutadiene resins include hydrogenated polybutadiene skeleton-containing resins, hydroxy group-containing polybutadiene resins, phenolic hydroxy group-containing polybutadiene resins, carboxy 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, and polyphenylene ether-polybutadiene resins.

[0092] Specific examples of polybutadiene resins include "Ricon 130MA8," "Ricon 130MA13," "Ricon 130MA20," "Ricon 131MA5," "Ricon 131MA10," "Ricon 131MA17," "Ricon 131MA20," and "Ricon 184MA6" (anhydride-containing polybutadienes) manufactured by Cray Valley Corporation; "GQ-1000" (hydroxyl- and carboxyl-introduced polybutadiene), "G-1000," "G-2000," and "G-3000" (polybutadiene having hydroxyl groups at both ends), "GI-1000," "GI-2000," and "GI-3000" (hydrogenated polybutadiene having hydroxyl groups at both ends) manufactured by Nippon Soda Co., Ltd.; and "FCA-061L" (a hydrogenated polybutadiene-based epoxy resin) manufactured by Nagase ChemteX Corporation.

[0093] Specific examples of polybutadiene resins include polyimide resins having a polybutadiene structure, a urethane structure, and an imide structure in the molecule. The polyimide resin can be produced as a linear polyimide resin (polyimides described in JP 2006-37083 A and WO 2008 / 153208 A) using hydroxyl-terminated polybutadiene, a diisocyanate compound, and a tetrabasic acid anhydride as raw materials. The content of the butadiene structure in the polyimide resin is preferably 60% to 95% by mass, more preferably 75% to 85% by mass. For details of the polyimide resin, please refer to the descriptions in JP 2006-37083 A and WO 2008 / 153208 A, the contents of which are incorporated herein by reference.

[0094] Resins containing a polycarbonate structure are sometimes referred to as “polycarbonate resins.” Examples of polycarbonate resins include hydroxy group-containing carbonate resins, phenolic hydroxy group-containing carbonate resins, carboxy group-containing carbonate resins, acid anhydride group-containing carbonate resins, isocyanate group-containing carbonate resins, and urethane group-containing carbonate resins.

[0095] Specific examples of polycarbonate resins include "FPC0220" manufactured by Mitsubishi Gas Chemical Company, Inc.; "T6002" and "T6001" (polycarbonate diols) manufactured by Asahi Kasei Corporation; and "C-1090," "C-2090," and "C-3090" (polycarbonate diols) manufactured by Kuraray Co., Ltd.

[0096] Specific examples of polycarbonate resins include polyimide resins having an imide structure, a urethane structure, and a polycarbonate structure in the molecule. The polyimide resin can be produced as a linear polyimide resin using a hydroxyl-terminated polycarbonate, a diisocyanate compound, and a tetrabasic acid anhydride as raw materials. The carbonate structure content of the polyimide resin is preferably 60% to 95% by mass, more preferably 75% to 85% by mass. For details of the polyimide resin, please refer to the description in International Publication No. 2016 / 129541, the contents of which are incorporated herein by reference.

[0097] A resin containing a polyalkylene structure is sometimes referred to as a "polyalkylene resin." As the polyalkylene resin, a resin containing an alkylene chain in the repeating unit can be used. The number of carbon atoms in the alkylene chain is preferably 2 or more, more preferably 3 or more, even more preferably 5 or more, and even more preferably 7 or more. The upper limit may be, for example, 36 or less, 15 or less, 10 or less, 8 or less, etc. As this polyalkylene resin, a resin containing a carbon skeleton derived from a dimer acid in the repeating unit is preferred.

[0098] The carbon skeleton derived from dimer acid refers to the skeleton of a divalent group remaining after removing the two terminal carboxyl groups (—COOH) of a dimer acid. Dimer acids are known compounds obtained by dimerizing unsaturated fatty acids (preferably those having 11 to 22 carbon atoms, more preferably those having 18 carbon atoms), and their industrial production process is largely standardized in the industry. Dimer acids are particularly readily available, primarily consisting of dimer acids having 36 carbon atoms, which are obtained by dimerizing unsaturated fatty acids having 18 carbon atoms, such as oleic acid and linoleic acid, which are inexpensive and readily available. Depending on the production method and the degree of purification, dimer acids may contain arbitrary amounts of monomer acids, trimer acids, other polymerized fatty acids, and the like. Although double bonds remain after the polymerization reaction of unsaturated fatty acids, in this specification, hydrogenated products obtained by further hydrogenation to reduce the degree of unsaturation are also included in the term dimer acids.

[0099] A polyalkylene resin containing a carbon skeleton derived from a dimer acid generally contains a divalent hydrocarbon group, and this divalent hydrocarbon group contains a carbon skeleton derived from a dimer acid. The divalent hydrocarbon group containing a carbon skeleton derived from a dimer acid usually has a long aliphatic carbon chain having 7 or more carbon atoms, and this long aliphatic carbon chain contains an alkylene chain. The divalent hydrocarbon group containing a carbon skeleton derived from a dimer acid may have 36 carbon atoms.

[0100] A specific example of a polyalkylene resin containing a carbon skeleton derived from a dimer acid is a polyimide resin containing a carbon skeleton derived from a dimer acid. Examples of such polyimide resins include resins obtained by the imidization reaction of a dimer acid-type diamine with a tetracarboxylic acid anhydride. The dimer acid-type diamine refers to a diamine compound having a structure in which the two terminal carboxyl groups (-COOH) of a dimer acid are substituted with an aminomethyl group (-CH-NH) or an amino group (-NH). Examples of dimer acid-type diamines include "PRIAMINE 1073," "PRIAMINE 1074," and "PRIAMINE 1075" manufactured by Croda Japan; and "VERSAMINE 551" and "VERSAMINE 552" manufactured by Cognis Japan. Furthermore, the tetracarboxylic acid anhydride may be an aliphatic tetracarboxylic acid dianhydride, an aromatic tetracarboxylic acid dianhydride, or a combination thereof.

[0101] A resin containing a polyalkyleneoxy structure is sometimes referred to as a "polyalkyleneoxy resin." The number of carbon atoms in the alkyleneoxy structure contained in the polyalkyleneoxy resin is preferably 2 to 15, more preferably 3 to 10, and even more preferably 5 to 8. Specific examples of alkyleneoxy resins include "EXA-4850-150," "EXA-4816," and "EXA-4822" manufactured by DIC Corporation; "EP-4000," "EP-4003," "EP-4010," and "EP-4011" manufactured by ADEKA Corporation; "BEO-60E" and "BPO-20E" manufactured by New Japan Chemical Co., Ltd.; and "YL7175" and "YL7410" manufactured by Mitsubishi Chemical Corporation.

[0102] Resins containing polysiloxane structures are sometimes referred to as “polysiloxane resins.” Examples of polysiloxane resins include “SMP-2006,” “SMP-2003PGMEA,” and “SMP-5005PGMEA” manufactured by Shin-Etsu Silicones Co., Ltd.; and linear polyimides made from amine-terminated polysiloxanes and tetrabasic acid anhydrides (see, for example, International Publication No. 2010 / 053185, Japanese Patent Application Laid-Open No. 2002-12667, and Japanese Patent Application Laid-Open No. 2000-319386).

[0103] Resins containing a poly(meth)acrylate structure are sometimes referred to as “poly(meth)acrylate resins.” Examples of poly(meth)acrylic resins include Teisan Resin manufactured by Nagase ChemteX Corporation; ME-2000, W-116.3, W-197C, KG-25, and KG-3000 manufactured by Negami Chemical Industrial Co., Ltd.; and ARUFON UH-2000 manufactured by Toagosei Co., Ltd.

[0104] Resins containing polyisoprene structures are sometimes called “polyisoprene resins.” Specific examples of polyisoprene resins include “KL-610” and “KL613” manufactured by Kuraray Co., Ltd.

[0105] Resins containing polyisobutylene structures are sometimes called "polyisobutylene resins." Specific examples of polyisobutylene resins include Kaneka Corporation's "SIBSTAR-073T" (styrene-isobutylene-styrene triblock copolymer) and "SIBSTAR-042D" (styrene-isobutylene diblock copolymer).

[0106] A resin containing a polystyrene structure is sometimes referred to as a "polystyrene resin." The polystyrene resin may be a copolymer containing, in combination with a styrene unit, any repeating unit different from the styrene unit, or may be a hydrogenated polystyrene resin. Examples of polystyrene resins include styrene-butadiene-styrene block copolymer (SBS), styrene-isoprene-styrene block copolymer (SIS), styrene-ethylene-butylene-styrene block copolymer (SEBS), styrene-ethylene-propylene-styrene block copolymer (SEPS), styrene-ethylene-ethylene-propylene-styrene block copolymer (SEEPS), styrene-butadiene-butylene-styrene block copolymer (SBBS), styrene-butadiene diblock copolymer, hydrogenated styrene-butadiene block copolymer, hydrogenated styrene-isoprene block copolymer, hydrogenated styrene-butadiene random copolymer, and styrene-maleic anhydride copolymer.

[0107] Specific examples of polystyrene resins include hydrogenated styrene-based thermoplastic elastomers "H1041," "Tuftec H1043," "Tuftec P2000," and "Tuftec MP10" (manufactured by Asahi Kasei Corporation); epoxidized styrene-butadiene thermoplastic elastomers "Epofriend AT501" and "CT310" (manufactured by Daicel Corporation); modified styrene-based elastomers having hydroxyl groups "Septon HG252" (manufactured by Kuraray Co., Ltd.); modified styrene-based elastomers having carboxyl groups "Tuftec N503M," modified styrene-based elastomers having amino groups "Tuftec N501," modified styrene-based elastomers having acid anhydride groups "Tuftec M1913" (manufactured by Asahi Kasei Corporation); unmodified styrene-based elastomers "Septon S8104" (manufactured by Kuraray Co., Ltd.); and styrene-ethylene / butylene-styrene block copolymers "FG1924" (manufactured by Kraton) and "EF-40" (manufactured by Cray Valley).

[0108] The (C) low elasticity polymer preferably has a glass transition temperature Tg of 25°C or lower, or is liquid at 25°C or lower. When the (C) low elasticity polymer has a glass transition temperature Tg of 25°C or lower, the glass transition temperature Tg is preferably 20°C or lower, more preferably 15°C or lower. The lower limit of the glass transition temperature Tg is not particularly limited, but is preferably -15°C or higher. When the (C) low elasticity polymer is liquid at 25°C or lower, the (C) low elasticity polymer is preferably liquid at 25°C, more preferably liquid at 20°C, and even more preferably liquid at 15°C. The glass transition temperature Tg can be measured by DSC (differential scanning calorimetry) at a heating rate of 5°C / min.

[0109] The (C) low-elasticity polymer may have a functional group capable of reacting with the (A) epoxy resin. When the (C) low-elasticity polymer is capable of reacting with the (A) epoxy resin, the mechanical strength of the cured resin composition can be increased. Functional groups capable of reacting with the epoxy resin include functional groups that appear upon heating. Examples of such functional groups include hydroxyl groups, carboxyl groups, acid anhydride groups, phenolic hydroxyl groups, epoxy groups, isocyanate groups, urethane groups, and maleimide groups (2,5-dihydro-2,5-dioxo-1H-pyrrol-1-yl groups). Among these, hydroxyl groups, acid anhydride groups, phenolic hydroxyl groups, epoxy groups, isocyanate groups, urethane groups, and maleimide groups are preferred, with phenolic hydroxyl groups being more preferred.

[0110] The amount of the (C) low elastic polymer is preferably 1% by mass or more, more preferably 2% by mass or more, particularly preferably 4% by mass or more, and is preferably 30% by mass or less, more preferably 20% by mass or less, and even more preferably 15% by mass or less, relative to 100% by mass of the nonvolatile components in the resin composition. When the amount of the (C) low elastic polymer is within the above range, the dielectric loss tangent and warpage can be effectively reduced, and usually, chemical resistance can also be effectively improved.

[0111] The amount of the (C) low elastic polymer is preferably 5% by mass or more, more preferably 10% by mass or more, particularly preferably 15% by mass or more, and is preferably 60% by mass or less, more preferably 50% by mass or less, and even more preferably 40% by mass or less, relative to 100% by mass of the resin component in the resin composition. When the amount of the (C) low elastic polymer is within the above range, the dielectric loss tangent and warpage can be effectively reduced, and usually, chemical resistance can also be effectively improved.

[0112] The total amount of the (B-1) flexible active ester resin and the (C) low-elasticity polymer is preferably 10% by mass or more, more preferably 15% by mass or more, even more preferably 20% by mass or more, and particularly preferably 30% by mass or more, relative to 100% by mass of the resin components in the resin composition, and is preferably 90% by mass or less, more preferably 70% by mass or less, and even more preferably 50% by mass or less. When the total amount of the (B-1) flexible active ester resin and the (C) low-elasticity polymer is within the above range, the dielectric loss tangent and warpage can be effectively reduced, and usually, chemical resistance can also be effectively improved.

[0113] <(D) Inorganic filler> The resin composition according to this embodiment includes an inorganic filler (D) as component (D). The inorganic filler (D) is a particle of an inorganic material. Therefore, the inorganic filler (D) is included in the resin composition in the form of particles, and is usually included in the cured product while maintaining this particle state. The inorganic filler (D) does not include those corresponding to the above-mentioned components (A) to (C).

[0114] (D) Inorganic fillers are typically made of inorganic compounds. Examples of (D) inorganic filler materials 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 titanate zirconate, barium zirconate, calcium zirconate, zirconium phosphate, and zirconium tungstate phosphate. Among these, silica and alumina are preferred, with silica being particularly preferred. Therefore, (D) inorganic fillers preferably contain silica, or may contain only silica. Examples of silica include amorphous silica, fused silica, crystalline silica, synthetic silica, and hollow silica. Moreover, the silica is preferably spherical silica. (D) The inorganic filler may be used alone or in combination of two or more kinds.

[0115] (D) Examples of commercially available inorganic fillers include "SP60-05" and "SP507-05" manufactured by Nippon Steel Chemical & Material Co., Ltd.; "YC100C," "YA050C," "YA050C-MJE," "YA010C," "SC2500SQ," "SO-C4," "SO-C2," and "SO-C1" manufactured by Admatechs Co., Ltd.; "UFP-30," "DAW-03," and "FB-105FD" manufactured by Denka Company, Limited; "Silfil NSS-3N," "Silfil NSS-4N," and "Silfil NSS-5N" manufactured by Tokuyama Corporation; "CellSpheres" and "MGH-005" manufactured by Taiheiyo Cement Corporation; and "Sferique" and "BA-1" manufactured by JGC Catalysts and Chemicals Co., Ltd.

[0116] The average particle size of the (D) inorganic filler is preferably 0.01 μm or more, more preferably 0.05 μm or more, even more preferably 0.1 μm or more, and preferably 10 μm or less, more preferably 5 μm or less, even more preferably 3 μm or less, even more preferably 1 μm or less.

[0117] (D) The average particle size of an inorganic filler can be measured by a laser diffraction / scattering method based on Mie scattering theory. Specifically, a volumetric particle size distribution of the inorganic filler is created using a laser diffraction / scattering particle size distribution analyzer, and the median diameter is used as the average particle size. A measurement sample can be prepared by weighing 100 mg of inorganic filler and 10 g of methyl ethyl ketone into a vial and dispersing the mixture ultrasonically for 10 minutes. The volumetric particle size distribution of the inorganic filler is measured using a laser diffraction particle size distribution analyzer with blue and red wavelength light sources using a flow cell system, and the average particle size can be calculated as the median diameter from the particle size distribution obtained. Examples of laser diffraction particle size distribution analyzers include the LA-960 manufactured by Horiba, Ltd.

[0118] (D) The specific surface area of ​​the inorganic filler is preferably 0.1 m 2 / g or more, more preferably 0.5m 2 / g or more, more preferably 1m 2 / g or more, particularly preferably 3m 2 / g or more, preferably 100m 2 / g or less, more preferably 70m 2 / g or less, more preferably 50m 2 / g or less, particularly preferably 40m 2 / g or less. (D) The specific surface area of ​​the inorganic filler can be measured in accordance with the BET method by adsorbing nitrogen gas onto the surface of a sample using a specific surface area measuring device (Macsorb HM-1210 manufactured by Mountech Co., Ltd.) and calculating the specific surface area using the BET multipoint method.

[0119] (D) The inorganic filler is preferably treated with a surface treatment agent from the viewpoint of improving moisture resistance and dispersibility. 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. One type of surface treatment agent may be used alone, or two or more types may be used in any combination.

[0120] Examples of commercially available surface treatment agents include Shin-Etsu Chemical Co., Ltd.'s "KBM403" (3-glycidoxypropyltrimethoxysilane), Shin-Etsu Chemical Co., Ltd.'s "KBM803" (3-mercaptopropyltrimethoxysilane), Shin-Etsu Chemical Co., Ltd.'s "KBE903" (3-aminopropyltriethoxysilane), Shin-Etsu Chemical Co., Ltd.'s "KBM573" (N-phenyl-3-aminopropyltrimethoxysilane), Shin-Etsu Chemical Co., Ltd.'s "SZ-31" (hexamethyldisilazane), Shin-Etsu Chemical Co., Ltd.'s "KBM103" (phenyltrimethoxysilane), Shin-Etsu Chemical Co., Ltd.'s "KBM-4803" (long-chain epoxy-type silane coupling agent), and Shin-Etsu Chemical Co., Ltd.'s "KBM-7103" (3,3,3-trifluoropropyltrimethoxysilane).

[0121] The degree of surface treatment with the surface treatment agent preferably falls within a specific range from the viewpoint of improving the dispersibility of the inorganic filler. Specifically, 100% by mass of the inorganic filler is preferably surface-treated with 0.2% to 5% by mass of the surface treatment agent, more preferably with 0.2% to 3% by mass of the surface treatment agent, and even more preferably with 0.3% to 2% by mass of the surface treatment agent.

[0122] The degree of surface treatment with the surface treatment agent can be evaluated by the amount of carbon per unit surface area of ​​the inorganic filler. From the viewpoint of improving the dispersibility of the inorganic filler, the amount of carbon per unit surface area of ​​the inorganic filler is set to 0.02 mg / m 2 More than 0.1 mg / m is preferable. 2More preferably, 0.2 mg / m or more 2 On the other hand, from the viewpoint of preventing an increase in the melt viscosity of the resin composition layer, it is more preferable that the amount of the resin composition layer is 1.0 mg / m 2 Preferably less than 0.8 mg / m 2 Less than 0.5 mg / m is more preferable. 2 The following is even more preferred:

[0123] (D) 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 solid content, the amount of carbon per unit surface area of ​​the inorganic filler can be measured using a carbon analyzer. An "EMIA-320V" manufactured by Horiba, Ltd., or the like can be used as the carbon analyzer.

[0124] The amount of (D) inorganic filler is preferably 50% by mass or more, more preferably 60% by mass or more, even more preferably 70% by mass or more, and is preferably 90% by mass or less, more preferably 85% by mass or less, even more preferably 80% by mass or less, based on 100% by mass of the nonvolatile components in the resin composition. When the amount of (D) inorganic filler is within this range, the dielectric loss tangent and warpage can be effectively reduced, and usually chemical resistance can also be effectively improved.

[0125] The total amount of (A) epoxy resin, (B) curing agent, (C) low-elasticity polymer, and (D) inorganic filler is preferably 70% by mass or more, more preferably 80% by mass or more, and even more preferably 90% by mass or more, based on 100% by mass of the nonvolatile components in the resin composition. The upper limit is usually 100% by mass or less, but may be 99.9% by mass or less.

[0126] <(E) Polymerizable unsaturated resin> The resin composition according to the present embodiment may contain a polymerizable unsaturated resin (E) as an optional component. The polymerizable unsaturated resin (E) as component (E) does not include those corresponding to the above-mentioned components (A) to (D). The polymerizable unsaturated resin (E) may be used alone or in combination of two or more.

[0127] The (E) polymerizable unsaturated resin may be a resin containing a non-aromatic carbon-carbon unsaturated bond. Therefore, the (E) polymerizable unsaturated resin typically has a polymerizable unsaturated group containing a non-aromatic carbon-carbon unsaturated bond. Examples of the polymerizable unsaturated group include unsaturated hydrocarbon groups such as vinyl, allyl, 1-propenyl, 3-cyclohexenyl, 3-cyclopentenyl, 2-vinylphenyl, 3-vinylphenyl, and 4-vinylphenyl; and α,β-unsaturated carbonyl groups such as acryloyl, methacryloyl, and maleimide. The (E) polymerizable unsaturated resin containing these polymerizable unsaturated groups typically undergoes radical polymerization. The (E) polymerizable unsaturated resin preferably has two or more polymerizable unsaturated groups.

[0128] Examples of (E) polymerizable unsaturated resins include (meth)acrylic polymerizable unsaturated resins, styrene polymerizable unsaturated resins, allyl polymerizable unsaturated resins, and maleimide polymerizable unsaturated resins.

[0129] As the (meth)acrylic polymerizable unsaturated resin, a resin having one or more, preferably two or more, acryloyl groups and / or methacryloyl groups in one molecule can be used. Examples of the (meth)acrylic polymerizable unsaturated resin include cyclohexane-1,4-dimethanol di(meth)acrylate, cyclohexane-1,3-dimethanol di(meth)acrylate, tricyclodecane dimethanol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,8-octanediol di(meth)acrylate, 1,9-nonane diol di(meth)acrylate, and the like. Low molecular weight (molecular weight less than 1000) aliphatic (meth)acrylic acid ester resins such as diol di(meth)acrylate, 1,10-decanediol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, trimethylolethane tri(meth)acrylate, glycerin tri(meth)acrylate, and pentaerythritol tetra(meth)acrylate; dioxane glycol di(meth)acrylate, 3,6-dioxa-1,8-octanediol di(meth)acrylate Examples of the ether-containing (meth)acrylic acid ester resins include low molecular weight (molecular weight less than 1000) acrylates, such as acrylate, 3,6,9-trioxaundecane-1,11-diol di(meth)acrylate, polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, 9,9-bis[4-(2-acryloyloxyethoxy)phenyl]fluorene, ethoxylated bisphenol A di(meth)acrylate, and propoxylated bisphenol A di(meth)acrylate; low molecular weight (molecular weight less than 1000) isocyanurate-containing (meth)acrylic acid ester resins, such as tris(3-hydroxypropyl)isocyanurate tri(meth)acrylate, tris(2-hydroxyethyl)isocyanurate tri(meth)acrylate, and ethoxylated isocyanuric acid tri(meth)acrylate; and high molecular weight (molecular weight 1000 or more) (meth)acrylic acid ester resins, such as (meth)acrylic-modified polyphenylene ether resins. The term "(meth)acrylic acid" includes acrylic acid, methacrylic acid, and combinations thereof, unless otherwise specified.Commercially available (meth)acrylic polymerizable unsaturated resins include, for example, "A-DOG" (dioxane glycol diacrylate) manufactured by Shin-Nakamura Chemical Co., Ltd., "DCP-A" (tricyclodecane dimethanol diacrylate), "DCP" (tricyclodecane dimethanol dimethacrylate), and "BPE-1300N" (ethoxylated bisphenol A dimethacrylate) manufactured by Kyoeisha Chemical Co., Ltd., "KAYARAD R-684" (tricyclodecane dimethanol diacrylate) and "KAYARAD R-604" (dioxane glycol diacrylate) manufactured by Nippon Kayaku Co., Ltd., and "SA9000" and "SA9000-111" (methacrylic-modified polyphenylene ether) manufactured by SABIC.

[0130] The styrene-based polymerizable unsaturated resin may be a resin having one or more, preferably two or more, vinyl groups directly bonded to an aromatic carbon atom in one molecule. Examples of the styrene-based polymerizable unsaturated resin include low-molecular-weight (molecular-weight less than 1000) styrene-based resins such as divinylbenzene, 2,4-divinyltoluene, 2,6-divinylnaphthalene, 1,4-divinylnaphthalene, 4,4'-divinylbiphenyl, 1,2-bis(4-vinylphenyl)ethane, 2,2-bis(4-vinylphenyl)propane, and bis(4-vinylphenyl)ether; and high-molecular-weight (molecular-weight 1000 or more) styrene-based resins such as vinylbenzyl-modified polyphenylene ether resin and styrene-divinylbenzene copolymer. Commercially available styrene-based polymerizable unsaturated resins include, for example, "ODV-XET(X03)", "ODV-XET(X04)", and "ODV-XET(X05)" (styrene-divinylbenzene copolymers) manufactured by Nippon Steel Chemical & Material Co., Ltd., and "OPE-2St 1200" and "OPE-2St 2200" (vinylbenzyl-modified polyphenylene ether resins) manufactured by Mitsubishi Gas Chemical Company, Inc.

[0131] As the allylic polymerizable unsaturated resin, a resin having one or more, preferably two or more, allyl groups in one molecule can be used. Examples of allyl-based polymerizable unsaturated resins include aromatic carboxylic acid allyl ester resins such as diallyl diphenate, triallyl trimellitate, diallyl phthalate, diallyl isophthalate, diallyl terephthalate, diallyl 2,6-naphthalenedicarboxylate, and diallyl 2,3-naphthalenecarboxylate; isocyanuric acid allyl ester resins such as 1,3,5-triallyl isocyanurate and 1,3-diallyl-5-glycidyl isocyanurate; epoxy-containing aromatic allyl resins such as 2,2-bis[3-allyl-4-(glycidyloxy)phenyl]propane; benzoxazine-containing aromatic allyl resins such as bis[3-allyl-4-(3,4-dihydro-2H-1,3-benzoxazin-3-yl)phenyl]methane; ether-containing aromatic allyl resins such as 1,3,5-triallyl ether benzene; and allyl silane resins such as diallyldiphenylsilane. Commercially available allyl polymerizable unsaturated resins include, for example, "TAIC" (1,3,5-triallyl isocyanurate) manufactured by Nippon Kasei Chemical Co., Ltd., "DAD" (diallyl diphenate) manufactured by Nisshoku Techno Fine Chemical Co., Ltd., "TRIAM-705" (triallyl trimellitate) manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., "DAND" (2,3-diallyl naphthalenecarboxylate) manufactured by Nisshoku Techno Fine Chemical Co., Ltd., and " Examples include "ALP-d" (bis[3-allyl-4-(3,4-dihydro-2H-1,3-benzoxazin-3-yl)phenyl]methane), "RE-810NM" (2,2-bis[3-allyl-4-(glycidyloxy)phenyl]propane) manufactured by Nippon Kayaku Co., Ltd., "DA-MGIC" (1,3-diallyl-5-glycidyl isocyanurate) manufactured by Shikoku Chemicals Corporation, and "NE-V-1100-70T" manufactured by DIC Corporation.

[0132] The maleimide-based polymerizable unsaturated resin may be a resin having one or more, preferably two or more, maleimide groups per molecule. The maleimide-based polymerizable unsaturated resin may be an aromatic maleimide resin having a maleimide group directly bonded to an aromatic ring, or an aliphatic maleimide resin having no maleimide group directly bonded to an aromatic ring. Commercially available maleimide-based radical polymerizable resins include, for example, "SLK-1500" (manufactured by Shin-Etsu Chemical Co., Ltd.), "SLK-2600" (manufactured by Shin-Etsu Chemical Co., Ltd.), "SLK-6895-T90" (manufactured by Shin-Etsu Chemical Co., Ltd.), "BMI-1500" (manufactured by Designer Molecules Inc.), "BMI-1700" (manufactured by Designer Molecules Inc.), "BMI-3000J" (manufactured by Designer Molecules Inc.), "BMI-689" (manufactured by Designer Molecules Inc.), and "BMI-2500" (manufactured by Designer Molecules Inc.). Examples of suitable maleimide resins include aliphatic maleimide resins containing an aliphatic skeleton (preferably an aliphatic skeleton derived from a dimer acid diamine), such as "MIR-3000-70MT" (manufactured by Nippon Kayaku Co., Ltd.), "BMI-4000" (manufactured by Daiwa Kasei Co., Ltd.), "BMI-80" (manufactured by Keiai Kasei Co., Ltd.), and "BMI-6100" (manufactured by Designer Molecules Inc.). Examples of suitable maleimide-based polymerizable unsaturated resins include the maleimide resin (maleimide compound containing an indane ring skeleton) disclosed in the Japan Institute of Invention and Innovation's Disclosure Technical Bulletin No. 2020-500211.

[0133] The polymerizable unsaturated group equivalent of (E) the polymerizable unsaturated resin is preferably 20 g / eq. to 3,000 g / eq., more preferably 50 g / eq. to 2,500 g / eq., even more preferably 70 g / eq. to 2,000 g / eq., and particularly preferably 90 g / eq. to 1,500 g / eq. The polymerizable unsaturated group equivalent represents the mass of the resin per equivalent of the polymerizable unsaturated group.

[0134] The weight average molecular weight (Mw) of the (E) polymerizable unsaturated resin is preferably 40,000 or less, more preferably 10,000 or less, even more preferably 5,000 or less, and particularly preferably 3,000 or less. The lower limit is not particularly limited, but can be, for example, 150 or more.

[0135] The amount of (E) polymerizable unsaturated resin is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, and even more preferably 1% by mass or more, relative to 100% by mass of nonvolatile components in the resin composition, and is preferably 30% by mass or less, more preferably 20% by mass or less, and even more preferably 10% by mass or less.

[0136] The amount of (E) polymerizable unsaturated resin is preferably 1% by mass or more, more preferably 2% by mass or more, particularly preferably 5% by mass or more, and is preferably 50% by mass or less, more preferably 40% by mass or less, and even more preferably 30% by mass or less, relative to 100% by mass of the resin components in the resin composition.

[0137] <(F)Organic filler> The resin composition according to this embodiment may contain an organic filler (F) as an optional component. The organic filler (F) as component (F) does not include those corresponding to the above-mentioned components (A) to (E). The organic filler (F) is usually incompatible with resin components other than the organic filler (F), is contained in the resin composition in the form of particles, and is contained in the cured product while maintaining this particle state. Furthermore, one type of organic filler (F) may be used alone, or two or more types may be used in combination.

[0138] The (F) organic filler may be particles of an organic material. A rubber component is preferred as the organic material contained in the (F) organic filler. Examples of rubber components include silicone-based elastomers such as polydimethylsiloxane; olefin-based thermoplastic elastomers such as polybutadiene, polyisoprene, polychlorobutadiene, ethylene-vinyl acetate copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-isobutylene copolymer, acrylonitrile-butadiene copolymer, isoprene-isobutylene copolymer, isobutylene-butadiene copolymer, ethylene-propylene-diene terpolymer, and ethylene-propylene-butene terpolymer; and thermoplastic elastomers such as acrylic thermoplastic elastomers such as polypropyl(meth)acrylate, polybutyl(meth)acrylate, polycyclohexyl(meth)acrylate, and polyoctyl(meth)acrylate. Furthermore, silicone-based rubbers such as polyorganosiloxane rubber may be mixed into the rubber component. The rubber component contained in the rubber particles has a glass transition temperature of, for example, 0°C or lower, preferably -10°C or lower, more preferably -20°C or lower, and even more preferably -30°C or lower.

[0139] The (F) organic filler may be a core-shell type rubber particle consisting of a core particle containing the above-mentioned rubber component and a shell portion formed by graft copolymerization of a monomer component copolymerizable with the rubber component contained in the core particle. Here, the term "core-shell type" does not necessarily refer only to those in which the core particle and the shell portion are clearly distinguishable, but also includes those in which the boundary between the core particle and the shell portion is unclear, and the core particle does not necessarily have to be completely covered with the shell portion.

[0140] Specific examples of (F) organic fillers include "CHT" manufactured by Samsung SDI; "B602" manufactured by Techno UMG; "Paraloid EXL-2602", "Paraloid EXL-2603", "Paraloid EXL-2655", "Paraloid EXL-2311", "Paraloid-EXL2313", "Paraloid EXL-2315", "Paraloid KM-330", "Paraloid KM-336P", and "Paraloid KCZ-201" manufactured by Dow; and "Metabrene C-223A" and "Metabrene E- 901," "Metabrene S-2001," "Metabrene W-450A," "Metabrene SRK-200," "Kane Ace M-511," "Kane Ace M-600," "Kane Ace M-400," "Kane Ace M-580," and "Kane Ace MR-01" manufactured by Kaneka Corporation, and "Staphyloid AC3355," "Staphyloid AC3816," "Staphyloid AC3816N," "Staphyloid AC3832," "Staphyloid AC4030," and "Staphyloid AC3364" manufactured by Aica Kogyo Co., Ltd.

[0141] The amount of (F) organic filler is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, even more preferably 0.5% by mass or more, relative to 100% by mass of the nonvolatile components in the resin composition, and is preferably 10% by mass or less, more preferably 5% by mass or less, even more preferably 1% by mass or less.

[0142] The amount of (F) organic filler is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and even more preferably 1% by mass or more, relative to 100% by mass of the resin component in the resin composition, and is preferably 20% by mass or less, more preferably 10% by mass or less, and even more preferably 5% by mass or less.

[0143] <(G) Curing accelerator> The resin composition according to the present embodiment may contain a (G) curing accelerator as an optional component. The (G) curing accelerator as component (G) does not include components (A) to (F) described above. The (G) curing accelerator acts as a catalyst for the reaction of the (A) epoxy resin, thereby accelerating the curing of the resin composition.

[0144] Examples of the (G) curing accelerator include phosphorus-based curing accelerators, urea-based curing accelerators, guanidine-based curing accelerators, imidazole-based curing accelerators, metal-based curing accelerators, amine-based curing accelerators, etc. One type of (G) curing accelerator may be used alone, or two or more types may be used in combination.

[0145] Examples of the phosphorus-based curing accelerator 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-butyldimethylphosphonium tetraphenylborate; methyltriphenylphosphonium bromide, ethyltriphenylphosphonium bromide, propyltriphenylphosphonium bromide, butyltriphenylphosphonium bromide, benzyltriphenylphosphonium chloride, tetraphenylphosphonium bromide, p-tolyltriphenylphosphonium tetra-p-tolylborate, and tetraphenylphosphonium tetra-p-tolylborate. aromatic phosphonium salts such as 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 adducts such as triphenylphosphine-p-benzoquinone adduct; aliphatic phosphines such as tributylphosphine, tri-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, tris(2,5-dimethylphenyl)phosphine, tris(2,6-dimethylphenyl)phosphine aromatic phosphines such as benzene, 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, and 2,2'-bis(diphenylphosphino)diphenyl ether;

[0146] Examples of the urea-based curing accelerator include 1,1-dimethylurea; aliphatic dimethylureas such as 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 toluene bis(dimethylurea), 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].

[0147] Examples of guanidine 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.

[0148] Examples of the imidazole curing accelerator include 2-methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 1,2-dimethylimidazole, 2-ethyl-4-methylimidazole, 1,2-dimethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 1-benzyl-2-methylimidazole, and 1-benzyl-2-methylimidazole. Phenylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-undecylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 1-cyanoethyl-2-phenylimidazole, 1-cyanoethyl-2-undecylimidazole, 1-cyanoethyl-2-phenylimidazolium trimellitate, 1-cyanoethyl-2-phenylimidazolium trimellitate, 2,4-diamino-6-[2'-methylimidazolyl -(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-undecylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-ethyl-4'-methylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine isocyanuric acid adduct, 2-phenylimidazole isocyanuric acid adduct Examples of imidazole compounds include 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 with epoxy resins. Commercially available imidazole curing accelerators include "1B2PZ," "2E4MZ," "2MZA-PW," "2MZ-OK," "2MA-OK," "2MA-OK-PW," "2PHZ," "2PHZ-PW," "Cl1Z," "Cl1Z-CN," "Cl1Z-CNS," and "C11Z-A" manufactured by Shikoku Chemicals Corporation; and "P200-H50" manufactured by Mitsubishi Chemical Corporation.

[0149] Examples of metal-based curing accelerators include organometallic complexes or organometallic salts of metals such as cobalt, copper, zinc, iron, nickel, manganese, and tin. Specific examples of organometallic complexes include organic cobalt complexes such as cobalt(II) acetylacetonate and cobalt(III) acetylacetonate, organic copper complexes such as copper(II) acetylacetonate, organic zinc complexes such as zinc(II) acetylacetonate, organic iron complexes such as iron(III) acetylacetonate, organic nickel complexes such as nickel(II) acetylacetonate, and organic manganese complexes such as manganese(II) acetylacetonate. Examples of organometallic salts include zinc octoate, tin octoate, zinc naphthenate, cobalt naphthenate, tin stearate, and zinc stearate.

[0150] Examples of the amine curing accelerator include trialkylamines such as triethylamine and tributylamine, 4-dimethylaminopyridine, benzyldimethylamine, 2,4,6-tris(dimethylaminomethyl)phenol, 1,8-diazabicyclo(5,4,0)-undecene, etc. Commercially available amine curing accelerators may be used, such as "MY-25" manufactured by Ajinomoto Fine-Techno Co., Inc.

[0151] The amount of (G) curing accelerator is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, even more preferably 0.1% by mass or more, relative to 100% by mass of non-volatile components in the resin composition, and is preferably 5% by mass or less, more preferably 2% by mass or less, even more preferably 1% by mass or less.

[0152] The amount of (G) curing accelerator is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, even more preferably 0.5% by mass or more, relative to 100% by mass of the resin component in the resin composition, and is preferably 10% by mass or less, more preferably 6% by mass or less, even more preferably 3% by mass or less.

[0153] <(H) Optional Additives> The resin composition according to this embodiment may further contain an optional additive (H) as an optional component. The optional additive (H) as component (H) does not include those corresponding to the above-mentioned components (A) to (G). Examples of the optional additive (H) include 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; antifoaming agents such as silicone-based antifoaming agents, acrylic-based antifoaming agents, fluorine-based antifoaming agents, and vinyl resin-based antifoaming agents; ultraviolet absorbers such as benzotriazole-based ultraviolet absorbers; adhesion improvers such as urea silanes; triazole-based adhesion promoters, tetrazole-based adhesion promoters, and triazine-based adhesion promoters. Examples of the additives include adhesion-imparting agents such as adhesion promoters, antioxidants such as hindered phenol antioxidants, fluorescent brighteners such as stilbene derivatives, surfactants such as fluorine-based surfactants and silicone-based surfactants, flame retardants such as phosphorus-based flame retardants (e.g., phosphate ester compounds, phosphazene compounds, phosphinic acid compounds, and red phosphorus), nitrogen-based flame retardants (e.g., melamine sulfate), halogen-based flame retardants, and inorganic flame retardants (e.g., antimony trioxide), dispersants such as phosphate ester-based dispersants, polyoxyalkylene-based dispersants, acetylene-based dispersants, silicone-based dispersants, anionic dispersants, and cationic dispersants, and stabilizers such as borate-based stabilizers, titanate-based stabilizers, aluminate-based stabilizers, zirconate-based stabilizers, isocyanate-based stabilizers, carboxylic acid-based stabilizers, and carboxylic anhydride-based stabilizers. (H) Optional additives may be used singly or in combination of two or more.

[0154] <(I) Solvent> The resin composition according to this embodiment may further contain (I) a solvent as an optional volatile component in addition to the non-volatile components (A) to (H) described above. The (I) solvent is typically an organic solvent. Examples of the organic solvent include ketone-based solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; ester-based solvents such as methyl acetate, ethyl acetate, butyl acetate, isobutyl acetate, isoamyl acetate, methyl propionate, ethyl propionate, and γ-butyrolactone; ether-based solvents such as tetrahydropyran, tetrahydrofuran, 1,4-dioxane, diethyl ether, diisopropyl ether, dibutyl ether, diphenyl ether, and anisole; alcohol-based solvents such as methanol, ethanol, propanol, butanol, and ethylene glycol; 2-ethoxyethyl acetate, propylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, ethyl diglycol acetate, γ-butyrolactone, and methyl methoxypropionate. Examples of suitable solvents include ether ester solvents such as ethyl acetate; ester alcohol solvents such as methyl lactate, ethyl lactate, and methyl 2-hydroxyisobutyrate; ether alcohol solvents such as 2-methoxypropanol, 2-methoxyethanol, 2-ethoxyethanol, propylene glycol monomethyl ether, and diethylene glycol monobutyl ether (butyl carbitol); amide solvents such as N,N-dimethylformamide, N,N-dimethylacetamide, and N-methyl-2-pyrrolidone; sulfoxide solvents such as dimethyl sulfoxide; nitrile solvents such as acetonitrile and propionitrile; aliphatic hydrocarbon solvents such as hexane, cyclopentane, cyclohexane, and methylcyclohexane; and aromatic hydrocarbon solvents such as benzene, toluene, xylene, ethylbenzene, and trimethylbenzene. (I) The solvents may be used singly or in combination of two or more.

[0155] The amount of (I) solvent, relative to 100% by mass of all components in the resin composition, can be, for example, 60% by mass or less, 40% by mass or less, 30% by mass or less, 20% by mass or less, 15% by mass or less, or 10% by mass or less, or may be 0% by mass.

[0156] <Method of manufacturing resin composition> The resin composition according to the present embodiment can be produced, for example, by mixing components that can be contained in the resin composition. The above-mentioned components may be mixed in part or all at the same time, or may be mixed sequentially. In the process of mixing each component, the temperature may be appropriately set, and thus heating and / or cooling may be performed temporarily or throughout. Furthermore, stirring or shaking may be performed in the process of mixing each component.

[0157] <Cured product of resin composition> By curing the resin composition, a cured product of the resin composition can be obtained. An insulating layer can be formed from this cured product. Since heat is usually applied when curing a resin composition, volatile components such as (I) the solvent, among the components contained in the resin composition, can volatilize due to the heat during curing. Therefore, the cured product obtained by curing the resin composition can contain non-volatile components such as components (A) to (H) or their reaction products.

[0158] The cured product of the resin composition according to this embodiment can have excellent dielectric properties, specifically, a low dielectric loss tangent Df. In one example, the dielectric loss tangent Df of the cured product is preferably 0.0050 or less, more preferably 0.0045 or less. The lower limit of the dielectric loss tangent Df is not particularly limited, and can be, for example, 0.0010 or more.

[0159] The dielectric loss tangent Df of the cured resin composition can be measured by the cavity resonance perturbation method at a measurement frequency of 5.8 GHz and a measurement temperature of 23°C. When the sample is an uncured resin composition, the resin composition may be cured at 200°C for 90 minutes to obtain a cured product, and the dielectric loss tangent Df of the cured product may be measured. A specific measurement method may be the method described in <Test Example 1: Measurement of Dielectric Loss Tangent Df> in the Examples section below.

[0160] When a cured product of the resin composition according to this embodiment is provided on a circuit board, warping of the circuit board can be suppressed. In one example, when the amount of warping is measured by the method described in <Test Example 2: Warpage Measurement Test> in the Examples section below, the range of the amount of warping is preferably less than 2,500 μm, more preferably 2,000 μm or less.

[0161] A cured product of the resin composition according to this embodiment typically exhibits excellent chemical resistance, specifically high resistance to alkaline aqueous solutions. For example, the mass loss of the cured product after immersion in a 1% by mass aqueous potassium hydroxide solution at 70°C for 1 hour is preferably less than 5% by mass, more preferably less than 4% by mass, and even more preferably less than 3% by mass. When the sample is a resin composition before curing, the resin composition may be cured at 200°C for 90 minutes to obtain a cured product, and the mass loss of the cured product may be measured. A specific measurement method may be the method described in "Test Example 3: Chemical Resistance Evaluation Test" in the Examples section below.

[0162] <Applications of resin composition> The resin composition according to this embodiment can be used to form an insulating layer, and is particularly preferably used to form an insulating layer for a circuit board. The resin composition may also be used to manufacture a resin sheet. Typically, an insulating layer is formed using this resin sheet. The resin composition may also be used for other purposes, such as solder resist, underfill material, die bonding material, hole filling resin, sealing resin, and component embedding resin.

[0163] <Resin sheet> A resin sheet according to one embodiment of the present invention includes a support and a resin composition layer formed on the support. The resin composition layer contains the resin composition described above, and preferably contains only the resin composition described above.

[0164] From the viewpoint of thinning, the thickness of the resin composition layer provided in the resin sheet is preferably 200 μm or less, more preferably 150 μm or less, and even more preferably 100 μm or less. The lower limit of the thickness of the resin composition layer can be, for example, 1 μm or more, 3 μm or more, 5 μm or more, etc.

[0165] Examples of the support include plastic film, metal foil, and release paper, with plastic film and metal foil being preferred.

[0166] When a film 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.

[0167] When a metal foil is used as the support, examples of the metal foil include copper foil and aluminum foil, with copper foil being preferred. The copper foil may be a foil made of a single metal, copper, or an alloy of copper and another metal (e.g., tin, chromium, silver, magnesium, nickel, zirconium, silicon, titanium, etc.).

[0168] The surface of the support that is to be bonded to the resin composition layer may be subjected to a surface treatment such as matte treatment, corona treatment, or antistatic treatment.

[0169] The support may be a support with a release layer, which has a release layer on the surface that bonds with the resin composition layer. Examples of the release agent used in the release layer of the support with a release layer include one or more release agents selected from the group consisting of alkyd-based release agents, polyolefin-based release agents, urethane-based release agents, and silicone-based release agents. Commercially available products may be used as the support with a release layer, including PET films having a release layer primarily composed of a silicone-based release agent or an alkyd resin-based release agent, such as "PET501010," "SK-1," "AL-5," and "AL-7" manufactured by Lintec Corporation; "Lumirror T60" manufactured by Toray Industries, Inc.; "Purex" manufactured by Teijin Limited; and "Uni-Peel" manufactured by Unitika Limited.

[0170] The thickness of the support is not particularly limited, but is preferably 1 μm or more, more preferably 5 μm or more, even more preferably 10 μm or more, and is preferably 75 μm or less, more preferably 60 μm or less, even more preferably 50 μm or less. When a support with a release layer is used, it is preferable that the thickness of the entire support with a release layer is within the above range.

[0171] The resin sheet may include any optional member as needed. For example, the resin sheet may include a protective film for protecting the resin composition layer. The protective film is usually provided on the surface of the resin composition layer that is not bonded to the support (i.e., the surface opposite to the support). The thickness of the protective film is not particularly limited, but is, for example, 1 μm to 40 μm. When the protective film is provided, adhesion of dust and scratches to the surface of the resin composition layer can be suppressed.

[0172] The resin sheet can be produced, for example, by a method including forming a resin composition layer on a support. Specifically, the resin sheet can be produced by applying a liquid (varnish-like) resin composition directly or by mixing a solvent and the resin composition to prepare a liquid (varnish-like) resin composition, applying the liquid (varnish-like) resin composition to a support, and then drying it as necessary to form a resin composition layer. The solvent may be the same as the (I) solvent described as a component of the resin composition.

[0173] The resin composition can be applied using a coating device such as a die coater. Drying can be performed by a drying method such as heating or hot air blowing. The drying conditions are not particularly limited, but drying is typically performed so that the solvent content in the resin composition layer is 10% by mass or less, preferably 5% by mass or less. Although this may vary depending on the boiling point of the solvent, for example, when a resin composition containing 30% by mass to 60% by mass of solvent is used, a resin composition layer can be formed by drying at 50°C to 150°C for 3 to 10 minutes.

[0174] The produced resin sheet can be stored by being wound up in a roll. When the resin sheet has a protective film, the resin sheet can usually be used by peeling off the protective film.

[0175] <Circuit board> A circuit board according to one embodiment of the present invention includes a cured product of the resin composition described above. Typically, the circuit board includes an insulating layer, and this insulating layer includes a cured product of the resin composition. The insulating layer may include only a cured product of the resin composition. The thickness of the insulating layer is not particularly limited and may be, for example, in the same range as the thickness of the resin composition layer included in the resin sheet. Furthermore, the insulating layer may typically have properties similar to those of the cured product of the resin composition described above.

[0176] Preferably, the circuit board includes an inner layer substrate and the insulating layer is provided on the inner layer substrate. The circuit board may also include a conductor layer. For example, the conductor layer may be provided on an insulating layer. An example of a preferred method for manufacturing a circuit board will be described below.

[0177] A preferred example of a method for manufacturing a circuit board includes the steps of: Step (I) of forming a resin composition layer on an inner layer substrate; a step (II) of curing the resin composition layer; Includes.

[0178] An "inner layer substrate" is a member that serves as the base material of a circuit board, and examples thereof include glass epoxy substrates, metal substrates, polyester substrates, polyimide substrates, BT resin substrates, and thermosetting polyphenylene ether substrates. The inner layer substrate may have a conductor layer on one or both sides. The conductor layer of the inner layer substrate may be patterned. An inner layer substrate having a conductor layer (circuit) formed on one or both sides of the substrate is sometimes called an "inner layer circuit board." The term "inner layer substrate" also includes intermediate products on which insulating layers and / or conductor layers are to be further formed during the production of a circuit board. In addition, inner layer substrates with built-in components may also be used.

[0179] The resin composition layer may be formed on the inner layer substrate by, for example, a method including applying a resin composition to the inner layer substrate and drying it as necessary, but is preferably formed using a resin sheet. The method for forming a resin composition layer using a resin sheet typically includes laminating the resin sheet and the inner layer substrate. The resin sheet and the inner layer substrate are laminated so that the resin composition layer of the resin sheet and the inner layer substrate are bonded. This lamination may be performed, for example, by thermocompression bonding the resin sheet to the inner layer substrate from the support side. Examples of a member for thermocompression bonding the resin sheet to the inner layer substrate (hereinafter also referred to as a "thermocompression bonding member") include a heated metal plate (such as a SUS panel) or a metal roll (such as a SUS roll). It is preferable to press the thermocompression bonding member not directly against the resin sheet but through an elastic material such as heat-resistant rubber so that the resin sheet can sufficiently conform to the surface irregularities of the inner layer substrate.

[0180] The lamination of the inner layer substrate and the resin sheet may be carried out by a vacuum lamination method. In the vacuum lamination method, the thermocompression temperature is preferably in the range of 60°C to 160°C, more preferably 80°C to 140°C, the thermocompression pressure is preferably in the range of 0.098MPa to 1.77MPa, more preferably 0.29MPa to 1.47MPa, and the thermocompression time is preferably in the range of 20 seconds to 400 seconds, more preferably 30 seconds to 300 seconds. The lamination is preferably carried out under reduced pressure conditions of 26.7hPa or less.

[0181] The lamination may be performed using a commercially available vacuum laminator, such as a vacuum pressure laminator manufactured by Meiki Seisakusho Co., Ltd., a vacuum applicator manufactured by Nikko Materials Co., Ltd., or a batch-type vacuum pressure laminator.

[0182] The method for manufacturing a circuit board may include smoothing the resin sheet after lamination under normal pressure (atmospheric pressure), for example, by pressing the resin sheet from the support side with a thermocompression member. The pressing conditions for the smoothing may be the same as those for the thermocompression bonding of the lamination. The smoothing may be performed using a commercially available laminator. The lamination and smoothing may be performed consecutively using the commercially available vacuum laminator.

[0183] The method for producing a circuit board according to this example includes a step (II) of curing the resin composition layer after the step (I). By curing the resin composition layer in the step (II), an insulating layer containing a cured product of the resin composition can be formed.

[0184] The resin composition layer is usually cured by thermal curing. The thermal curing conditions for the resin composition layer may vary depending on the type of resin composition. For example, 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.

[0185] The method for producing a circuit board may include preheating the resin composition layer at a temperature lower than the curing temperature before thermally curing the resin composition layer. For example, prior to thermally curing the resin composition layer, the resin composition layer may be preheated for typically 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, at a temperature of typically 50°C to 150°C, preferably 60°C to 140°C, and more preferably 70°C to 130°C. Preheating is typically carried out after step (I). Furthermore, when a smoothing treatment is carried out after laminating the inner layer substrate and the resin sheet, preheating can typically be carried out after the smoothing treatment.

[0186] When a resin sheet is used, the method for producing a circuit board may include a step of peeling off the support of the resin sheet after laminating the inner layer substrate and the resin sheet. The peeling off of the support may be performed between steps (I) and (II), or after step (II). Furthermore, when the method for producing a circuit board includes step (III) of forming holes in the insulating layer, step (IV) of roughening the insulating layer, and step (V) of forming a conductor layer, as described below, the peeling off of the support may be performed between steps (II) and (III), between steps (III) and (IV), or between steps (IV) and (V).

[0187] The method for producing a circuit board may include, after step (II), step (III) of forming holes such as via holes or through holes in the insulating layer. The method for forming the holes may be selected depending on factors such as the composition of the resin composition used to form the insulating layer. For example, holes may be formed by processing methods such as drilling, laser processing, and plasma processing, with laser processing being preferred. For example, holes may be formed by irradiating the insulating layer with laser light after peeling off the support, or by irradiating the insulating layer with laser light through the support. The dimensions and shape of the holes may be determined appropriately depending on the design of the circuit board.

[0188] The method for manufacturing a circuit board may include a step (IV) of roughening the insulating layer. The roughening treatment can roughen the surface of the insulating layer. The roughening treatment can also remove smears (resin residues) from the insulating layer. Therefore, this roughening treatment is sometimes called a "desmear treatment." For example, when holes are formed in step (III), smears may form in the holes. Therefore, it is preferable to perform the roughening treatment of step (IV) after step (III) to remove the smears.

[0189] The procedure and conditions for the roughening treatment are not particularly limited, and known procedures and conditions that are commonly used when forming an insulating layer for a circuit board can be adopted. For example, the roughening treatment may be performed by subjecting the insulating layer to a swelling treatment using a swelling liquid, an oxidation treatment using an oxidizing agent, and a neutralization treatment using a neutralizing liquid in this order.

[0190] Examples of swelling liquids used in the roughening treatment include alkaline solutions and surfactant solutions, with alkaline solutions being preferred. Sodium hydroxide solutions and potassium hydroxide solutions are more preferred as alkaline solutions. Commercially available swelling liquids include "Swelling Dip Securiganth P" and "Swelling Dip Securiganth SBU" manufactured by Atotech Japan. Swelling treatment using a swelling liquid can be performed, for example, by immersing the insulating layer in a swelling liquid at 30°C to 90°C for 1 to 20 minutes. To keep the swelling of the resin in 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.

[0191] Examples of oxidizing agents used in the roughening treatment include alkaline permanganate solutions prepared by dissolving potassium permanganate or sodium permanganate in an aqueous solution of sodium hydroxide. Oxidation treatment using an oxidizing agent such as alkaline permanganate solution is preferably carried out by immersing the insulating layer in an oxidizing agent solution heated to 60°C to 100°C for 10 to 30 minutes. The concentration of permanganate in the alkaline permanganate solution is preferably 5% by mass to 10% by mass. Commercially available oxidizing agents include alkaline permanganate solutions such as "Concentrate Compact CP" and "Dosing Solution Securigance P" manufactured by Atotech Japan.

[0192] The neutralizing solution used in the roughening treatment is preferably an acidic aqueous solution, and a commercially available product such as "Reduction Solution Securigant P" manufactured by Atotech Japan can be cited as an example. Neutralization treatment using a neutralizing solution can be carried out by immersing the surface that has been oxidized with an oxidizing agent in a neutralizing solution at 30°C to 80°C for 5 to 30 minutes. From the standpoint of workability, a preferred method is to immerse the object that has been oxidized with an oxidizing agent in a neutralizing solution at 40°C to 70°C for 5 to 20 minutes.

[0193] The method for producing a circuit board may include step (V) of forming a conductor layer on the insulating layer. When the method for producing a circuit board includes step (III) or (IV), step (V) of forming a conductor layer is usually preferably carried out after steps (III) and (IV).

[0194] The conductive material used for the conductor layer is not particularly limited. In a preferred embodiment, the conductor layer contains one or more metals selected from the group consisting of gold, platinum, palladium, silver, copper, aluminum, cobalt, chromium, zinc, nickel, titanium, tungsten, iron, tin, and indium. The conductor layer may be a single metal layer or an alloy layer. Examples of alloy layers include layers formed from alloys of two or more metals selected from the above group (e.g., nickel-chromium alloys, copper-nickel alloys, and copper-titanium alloys). Among these, from the viewpoints of versatility in forming the conductor layer, cost, ease of patterning, and the like, a single metal layer of chromium, nickel, titanium, aluminum, zinc, gold, palladium, silver, or copper, or an alloy layer of a nickel-chromium alloy, copper-nickel alloy, or 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.

[0195] The conductor layer may have a single layer structure or a multi-layer structure including two or more single metal or alloy layers made of different types of metals or alloys. 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.

[0196] The thickness of the conductor layer depends on the design of the circuit board, but is preferably 3 μm to 35 μm, and more preferably 5 μm to 30 μm.

[0197] 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. From the viewpoint of ease of production, the semi-additive method is preferred. An example of forming a conductor layer by a semi-additive method will be described below.

[0198] First, an electroless plated layer (plating seed layer) is formed on the surface of the insulating layer by electroless plating. Next, a mask pattern is formed on the formed electroless plated layer, exposing a portion of the electroless plated layer corresponding to the desired wiring pattern. After forming an electroless plated layer on the exposed electroless plated layer by electrolytic plating, the mask pattern is removed. Thereafter, unnecessary electroless plated layer is removed by etching, thereby forming a conductor layer having the desired wiring pattern.

[0199] As another example, the conductor layer may be formed using a metal foil. When a metal foil is used to form the conductor layer, step (V) is preferably performed 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 using the metal foil on the insulating layer by a known technique such as a subtractive method or a modified semi-additive method. The metal foil can be manufactured by a known method such as an electrolytic method or a rolling method. Commercially available metal foils include, for example, HLP foil and JXUT-III foil manufactured by JX Nippon Mining & Smelting Co., Ltd., and 3EC-III foil and TP-III foil manufactured by Mitsui Mining & Smelting Co., Ltd.

[0200] When a conductor layer is formed on an insulating layer, the method for manufacturing a circuit board may include performing an annealing treatment after the formation of the conductor layer. The annealing treatment can improve the adhesion between the insulating layer and the conductor layer. The annealing treatment can be performed, for example, by heating at 150°C to 210°C for 20 to 180 minutes.

[0201] In the method for manufacturing a circuit board, each of the above steps may be performed only once or may be repeated two or more times. For example, steps (I) to (V) may be performed repeatedly to form a circuit board having a multilayer structure, such as a multilayer printed wiring board having a plurality of insulating layers and conductor layers.

[0202] The method for manufacturing a circuit board may include any additional steps in addition to the steps described above. For example, the method for manufacturing a circuit board may include a step of providing a semiconductor chip so that the semiconductor chip is bonded to the conductor layer. Specifically, when manufacturing a circuit board for a semiconductor chip package including a semiconductor chip, the method for manufacturing a circuit board may include a step of providing the semiconductor chip. The semiconductor chip may be bonded under appropriate conditions that allow conductive connection between the terminal electrodes of the semiconductor chip and the conductor layer formed on the insulating layer. For example, conditions used in flip-chip mounting may be used. The semiconductor chip may be bonded via an insulating adhesive or by reflow bonding. If necessary, the provided semiconductor chip may be filled with a mold underfill material. The method for manufacturing a circuit board may also include, for example, a step of forming a sealing layer, a step of forming a solder resist layer, and a step of dicing the manufactured circuit board into individual pieces.

[0203] Examples of circuit boards include printed wiring boards and semiconductor chip packages. Examples of semiconductor chip packages include FC-CSP, MIS-BGA package, ETS-BGA package, fan-out type WLP (Wafer Level Package), fan-in type WLP, fan-out type PLP (Panel Level Package), and fan-in type PLP. In these semiconductor chip packages, it is preferable to form a rewiring formation layer as an insulating layer using a cured product obtained by curing the above-mentioned resin composition. However, the circuit board is not limited to those exemplified here.

[0204] <Semiconductor device> The circuit board can be used to manufacture a semiconductor device. The semiconductor device includes the circuit board described above. Examples of the semiconductor device include various semiconductor devices used in electrical appliances (e.g., computers, mobile phones, smartphones, tablet devices, wearable devices, digital cameras, medical equipment, and televisions) and vehicles (e.g., motorcycles, automobiles, trains, ships, and aircraft). [Example]

[0205] The present invention will be specifically described below with reference to examples, although the present invention is not limited to these examples. In the following description, "parts" and "%" representing amounts mean "parts by mass" and "% by mass", respectively, unless otherwise specified. Furthermore, unless otherwise specified, the temperature and pressure conditions were room temperature (23°C) and atmospheric pressure (1 atm). Furthermore, in the following description, "aromatic polycarboxylic acids" refers to aromatic polycarboxylic acids, their acid halides, and / or their esters.

[0206] <Synthesis Example 1: Synthesis of diphenyl isophthalate derivative (b'-1)> A flask equipped with a thermometer, dropping funnel, condenser, fractionating column, and stirrer was charged with 808.0 parts by mass of isophthalic acid chloride (4.0 moles of acid chloride groups) as aromatic polycarboxylic acid (b1) and 4140.0 parts by mass of toluene. The system was purged with nitrogen under reduced pressure and dissolved. Next, 864.0 parts by mass (8.0 moles) of o-cresol (b2) as monohydroxy aromatic compound was charged and the system was purged with nitrogen and dissolved. 2.07 parts by mass of tetrabutylammonium bromide was then dissolved. While purging with nitrogen gas, the system was controlled to 60°C or below, and 1648.0 parts by mass of 20% aqueous sodium hydroxide solution was added dropwise over 3 hours. Stirring was then continued under these conditions for 1 hour. After the reaction was completed, the mixture was allowed to stand for separation, and the aqueous layer was removed. Water was then added to the toluene layer containing the dissolved reactant, and the mixture was stirred and mixed for approximately 15 minutes. The mixture was then allowed to stand for separation, and the aqueous layer was removed. This operation was repeated until the pH of the aqueous layer reached 7. Thereafter, water and toluene were removed by decanting, and a crystalline compound (intermediate product (b')), a diphenyl isophthalate derivative (b'-1), was obtained.

[0207] <Synthesis Example 2: Synthesis of diphenyl isophthalate derivative (b'-2)> A flask equipped with a thermometer, dropping funnel, condenser, fractionating column, and stirrer was charged with 142.1 parts by mass of isophthalic acid chloride (0.7 moles of acid chloride groups) as aromatic polycarboxylic acid (b1) and 954.0 parts by mass of toluene. The system was then purged with nitrogen under reduced pressure to allow dissolution. Next, 188.0 parts by mass (1.4 moles) of phenol (b2) as monohydroxyaromatic compound was charged and the system was purged with nitrogen under reduced pressure to allow dissolution. Then, 0.33 parts by mass of tetrabutylammonium bromide was dissolved. While purging with nitrogen gas, the system was controlled to 60°C or below, and 288.4 parts by mass of 20% aqueous sodium hydroxide solution was added dropwise over 3 hours. Stirring was then continued under these conditions for 1 hour. After completion of the reaction, the mixture was allowed to stand for separation, and the aqueous layer was removed. Water was then added to the toluene layer containing the dissolved reactant, and the mixture was stirred and mixed for approximately 15 minutes. The mixture was then allowed to stand for separation, and the aqueous layer was removed. This procedure was repeated until the pH of the aqueous layer reached 7. Water and toluene were then removed by decanting, yielding a crystalline compound (intermediate product (b')), a diphenyl isophthalate derivative (b'-2).

[0208] <Synthesis Example 3: Synthesis of diphenyl isophthalate derivative (b'-3)> A flask equipped with a thermometer, dropping funnel, condenser, fractionating column, and stirrer was charged with 142.1 parts by mass of isophthalic acid chloride (0.7 moles of acid chloride groups) as aromatic polycarboxylic acid (b1) and 903.0 parts by mass of toluene. The system was then purged with nitrogen under reduced pressure and dissolved. Next, 210.0 parts by mass (1.4 moles) of p-tert-butylphenol (hereinafter sometimes abbreviated as "PTBP") as monohydroxyaromatic compound (b2) was charged and the system was purged with nitrogen under reduced pressure and dissolved. Then, 0.45 parts by mass of tetrabutylammonium bromide was dissolved. While purging with nitrogen gas, the system was controlled to 60°C or below, and 288.4 parts by mass of 20% aqueous sodium hydroxide solution was added dropwise over 3 hours. Stirring was then continued under these conditions for 1 hour. After the reaction was completed, the mixture was allowed to stand for separation, and the aqueous layer was removed. Water was then added to the toluene layer containing the dissolved reactant, and the mixture was stirred and mixed for approximately 15 minutes. The mixture was then left to stand and separated, and the aqueous layer was removed. This procedure was repeated until the pH of the aqueous layer reached 7. Water and toluene were then removed by decanting, yielding the isophthalic acid diphenyl derivative (b'-3), a crystalline compound (intermediate product (b')).

[0209] <Synthesis Example 4: Synthesis of soft activated ester compound (b-1)> A flask equipped with a thermometer, dropping funnel, condenser, fractionating column, and stirrer was charged with 30.0 g of 1,9-nonanediol (hydroxyl equivalent: 80 g / eq) as the polyhydric alcohol compound (b3), 129.68 g of the isophthalic acid diphenyl derivative (b'-1) obtained in Synthesis Example 1 as the intermediate product (b'), and 0.80 g of 1,8-diazabicyclo[5,4,0]-undecene-7 (hereinafter sometimes abbreviated as "DBU"), and the mixture was heated to 190 °C and stirred until the reaction was complete. The completion of the reaction was confirmed by gel permeation chromatography (GPC). The o-cresol was then removed by vacuum distillation to obtain the flexible activated ester resin (b-1) shown in the following formula (b-1). The active ester group equivalent weight and average repeat number n7 of the obtained flexible active ester resin (b-1) were 319 g / eq. and n7=1, respectively, based on the charge ratio.

[0210] [ka]

[0211] The average repeat number n7 in the flexible activated ester resin (b-1) represented by the above formula (b-1) was calculated from the charge ratio according to the following formula (M1). (Average repeat number n7 in the obtained flexible activated ester resin (b-1)) = (number of moles of hydroxyl groups in the polyhydric alcohol compound (b3)) / [(number of moles of active ester groups in the intermediate product (b') used as a raw material) - (number of moles of hydroxyl groups in the polyhydric alcohol compound (b3)] (M1)

[0212] <Synthesis Example 5: Synthesis of flexible activated ester resin (b-2)> A flask equipped with a thermometer, dropping funnel, condenser, fractionating column, and stirrer was charged with 30.0 parts by mass of 1,9-nonanediol (hydroxyl group equivalent: 80 g / eq) as the polyhydric alcohol compound (b3), 119.18 parts by mass of the isophthalic acid diphenyl derivative (b'-2) obtained in Synthesis Example 2 as the intermediate product (b'), and 0.75 parts by mass of DBU. The system was then purged with nitrogen under reduced pressure, and the temperature was raised to 190°C and the reaction was stirred until completion. The completion of the reaction was confirmed by GPC. Phenol was then removed by vacuum distillation to obtain the flexible activated ester resin (b-2) shown in formula (b-2) below. The active ester group equivalent and average repeat number n8 of the obtained flexible activated ester resin (b-2) were 306 g / eq. and n8 = 1, respectively, based on the charge ratio.

[0213] [ka]

[0214] <Synthesis Example 6: Synthesis of flexible activated ester resin (b-3)> A flask equipped with a thermometer, dropping funnel, condenser, fractionating column, and stirrer was charged with 8.5 parts by mass of 1,9-nonanediol (hydroxyl group equivalent: 80 g / eq) as the polyhydric alcohol compound (b3), 45.67 parts by mass of the isophthalic acid diphenyl derivative (b'-3) obtained in Synthesis Example 3 as the intermediate product (b'), and 0.27 parts by mass of DBU. The system was then purged with nitrogen under reduced pressure, and the temperature was raised to 190 °C and the reaction was stirred until completion. The completion of the reaction was confirmed by GPC. PTBP was then removed by vacuum distillation to obtain the flexible active ester compound (b-3) shown in formula (b-3) below. The active ester group equivalent and average repeat number n9 of the resulting flexible active ester resin (b-3) were 363 g / eq. and n9 = 1, respectively, based on the charge ratio.

[0215] [ka]

[0216] <Synthesis Example 7: Synthesis of flexible activated ester resin (b-4)> The same procedure as in Synthesis Example 4 was carried out, except that in Synthesis Example 4, 1,9-nonanediol was replaced with 30.0 parts by mass of 1,6-hexanediol (hydroxyl group equivalent: 59 g / eq) as the polyhydric alcohol compound (b3), the amount of diphenyl isophthalate derivative (b'-1) was changed from 129.68 parts by mass to 175.86 parts by mass, and the amount of DBU was changed from 0.80 parts by mass to 1.03 parts by mass, to obtain a flexible active ester resin (b-4) represented by the following formula (b-4). The active ester group equivalent and average repeat number n of the obtained flexible active ester resin (b-4) were 10 From the feed ratio, 299g / eq. and n 10 =1.

[0217] [ka]

[0218] <Synthesis Example 8: Synthesis of flexible activated ester resin (b-5)> The same procedure as in Synthesis Example 4 was carried out, except that in Synthesis Example 4, 1,9-nonanediol was replaced with 40.0 parts by mass of 1,12-dodecanediol (hydroxyl group equivalent: 101 g / eq) as the polyhydric alcohol compound (b3), the amount of diphenyl isophthalate derivative (b'-1) was changed from 129.68 parts by mass to 136.95 parts by mass, and the amount of DBU was changed from 0.80 parts by mass to 0.88 parts by mass, to obtain a flexible active ester resin (b-5) represented by the following formula (b-5). The active ester group equivalent and average repeat number n of the obtained flexible active ester resin (b-5) were 11 From the feed ratio, 342g / eq. and n 11 =1.

[0219] [ka]

[0220] <Synthesis Example 9: Synthesis of low modulus polymer (c-1)> A reaction vessel was charged with 69 g of bifunctional hydroxy-terminated polybutadiene ("G-3000" manufactured by Nippon Soda Co., Ltd., number average molecular weight = 3000, hydroxy group equivalent weight = 1800 g / eq.), 40 g of PGMEA (propylene glycol monomethyl ether acetate manufactured by Showa Denko K.K.), and 0.005 g of dibutyltin laurate, which were mixed and dissolved uniformly. Once homogeneous, the mixture was heated to 60°C, and 8 g of isophorone diisocyanate ("IPDI" manufactured by Evonik Degussa Japan Co., Ltd., isocyanate group equivalent weight = 113 g / eq.) was added with further stirring, and the reaction was carried out for approximately 3 hours.

[0221] Next, 23 g of cresol novolak resin (DIC Corporation "KA-1160", hydroxyl group equivalent = 117 g / eq.) and 60 g of PGMEA were added to the reaction mixture, and the mixture was refluxed at 150 °C with stirring and reacted for about 10 hours. -1The disappearance of the NCO peak was confirmed. The disappearance of the NCO peak was considered to be the end point of the reaction, and the reaction mixture was cooled to room temperature. The reaction mixture was then filtered through a 100-mesh filter cloth to obtain a low-elasticity polymer (c-1) having a butadiene structure and a phenolic hydroxyl group (phenolic hydroxyl group-containing butadiene resin: non-volatile components 50% by mass). The weight-average molecular weight of the low-elasticity polymer (c-1) was 27,000, and the glass transition temperature was -7°C.

[0222] The modulus of elasticity of the obtained low-elastic polymer (c-1) was measured using the following modulus measurement method. That is, a polyethylene terephthalate film (Toray Industries, Inc., "Lumirror R80," thickness 38 μm, softening point 130 ° C.) that had been subjected to a release treatment with an alkyd resin-based release agent (Lintec Corporation, "AL-5") was prepared. The low-elastic polymer (c-1) was uniformly coated on the support using a die coater so that the dried polymer layer had a thickness of 50 μm, and dried at 70 ° C. to 120 ° C. for 10 minutes to form a low-elastic polymer layer. This low-elastic polymer layer was peeled from the support, and the modulus was measured using a tensile test (temperature 25 ° C., humidity 40% RH) in accordance with JIS K7161, confirming that the low-elastic polymer (c-1) had a modulus of elasticity of 0.05 GPa.

[0223] <Synthesis Example 10: Synthesis of low modulus polymer (c-2)> A flask equipped with a stirrer, thermometer, and condenser was charged with 368.41 g of ethyl diglycol acetate and 368.41 g of an aromatic solvent ("Solvesso 150 (registered trademark)" manufactured by ExxonMobil Corporation) as a solvent. Furthermore, 100.1 g (0.4 mol) of diphenylmethane diisocyanate and 400 g (0.2 mol) of polycarbonate diol ("C-2015N" manufactured by Kuraray Co., Ltd., number average molecular weight: approximately 2000, hydroxyl equivalent: 1000 g / eq., non-volatile components: 100% by mass) were charged to the flask, and the reaction was carried out at 70°C for 4 hours. This produced a first reaction solution.

[0224] Next, 195.9 g (0.2 mol) of nonylphenol novolac resin (hydroxyl group equivalent: 229.4 g / eq, average 4.27 functional groups, average calculated molecular weight: 979.5 g / mol) and 41.0 g (0.1 mol) of ethylene glycol bisanhydrotrimellitate were further charged into the flask, and the temperature was raised to 150 ° C. over 2 hours and the reaction was carried out for 12 hours. This resulted in a second reaction solution. FT-IR showed a peak at 2250 cm -1 The disappearance of the NCO peak was confirmed. The disappearance of the NCO peak was considered to be the end point of the reaction, and the second reaction solution was cooled to room temperature. The second reaction solution was then filtered through a 100-mesh filter cloth. As a result, a low-elasticity polymer (c-2) having phenolic hydroxyl groups (phenolic hydroxyl group-containing polycarbonate resin: non-volatile components 50% by mass) was obtained as a filtrate. The weight-average molecular weight of the low-elasticity polymer (c-2) was 20,000, and the glass transition temperature was 5°C. The elastic modulus of the low-elasticity polymer (c-2) was confirmed to be 0.5 GPa as measured by a tensile test (temperature 25°C, humidity 40% RH) in accordance with JIS K7161 using the same elastic modulus measurement method as for the low-elasticity polymer (c-1).

[0225] <Synthesis Example 11: Synthesis of low modulus polymer (c-3)> A 1-L separable flask equipped with an oil bath and a stirrer was charged with 200 g of cyclohexanone while introducing nitrogen gas. Then, 149.4 g of a dimer acid diamine ("PRIAMINE 1075" manufactured by Croda Japan) and 4.7 g of m-aminophenol were added with stirring. Subsequently, 67.3 g of 1,2,4,5-cyclohexanetetracarboxylic dianhydride were added as a tetracarboxylic acid and stirred at room temperature for 30 minutes. The mixture was heated to 100 °C and stirred for 3 hours. After that, the oil bath was removed and the mixture was returned to room temperature to obtain a varnish-like polyimide precursor. The mixture was then heated at 170 °C for 10 hours while removing the distilled water from the system using a Dean-Stark trap. This resulted in imidization, yielding a low-modulus polymer (c-3) (50% nonvolatiles) with a dimer acid-derived carbon skeleton. The weight-average molecular weight of the resulting low-modulus polymer (c-3) was 10,000. Using the same elastic modulus measurement method as for the low-elasticity polymer (c-1), the elastic modulus of the low-elasticity polymer (c-3) was confirmed to be 0.2 GPa as measured by a tensile test (temperature 25°C, humidity 40% RH) in accordance with JIS K7161.

[0226] <Synthesis Example 12: Synthesis of maleimide resin (e-1)> An MEK solution (60% by mass of non-volatile components) of maleimide resin (e-1) synthesized by the method described in Synthesis Example 1 of Japan Institute of Invention and Innovation Disclosure Technical Bulletin No. 2020-500211 was prepared. This maleimide resin (e-1) had a structure represented by the following formula (e-1) and a weight-average molecular weight of 2,000.

[0227] [ka]

[0228] <Examples 1 to 12 and Comparative Examples 1 to 3> (1) Preparation of resin composition: Each component was weighed and mixed in the amount (parts by mass) shown in Tables 1 to 3 below, and then 15 parts of MEK and 15 parts of cyclohexanone were added and uniformly dispersed using a high-speed rotating mixer to obtain a resin composition (resin varnish). Details of each component shown in Tables 1 to 3 below are as follows.

[0229] (A) Active ester resin: "NC-3000": Biphenyl aralkyl epoxy resin (manufactured by Nippon Kayaku Co., Ltd., epoxy equivalent weight approximately 275g / eq.) "ZX-1059": Bisphenol epoxy resin (manufactured by Nippon Steel Chemical & Material Co., Ltd., a 1:1 mixture of bisphenol A and bisphenol F, epoxy equivalent weight 169g / eq.) "HP4032SS": Naphthalene-type epoxy resin (DIC Corporation, epoxy equivalent weight: approximately 144 g / eq.) "YX4000H": Bixylenol-type epoxy resin (manufactured by Mitsubishi Chemical Corporation, epoxy equivalent weight approximately 185g / eq.)

[0230] (B-1) Flexible activated ester resin: "EXB-LE-P01": an activated ester resin having a polybutadiene skeleton (a resin represented by formula (b-6), manufactured by DIC Corporation, active group equivalent weight 990 g / eq., non-volatile components 58% by mass) "b-1": Flexible activated ester resin (b-1) synthesized in Synthesis Example 4, active ester group equivalent weight 319 g / eq. "b-2": Flexible activated ester resin (b-2) synthesized in Synthesis Example 5, active ester group equivalent weight 306 g / eq. "b-3": Flexible activated ester resin (b-3) synthesized in Synthesis Example 6, active ester group equivalent weight 363 g / eq. "b-4": Flexible activated ester resin (b-4) synthesized in Synthesis Example 7, active ester group equivalent weight 299 g / eq. "b-5": Flexible activated ester resin (b-5) synthesized in Synthesis Example 8, active ester group equivalent weight 342 g / eq.

[0231] (B-2) Optional hardener: "HPC-8000-65T": Activated ester resin (DIC Corporation, activated ester group equivalent weight approximately 223 g / eq., toluene solution with 65% non-volatile content) "LA3018-50P": Triazine skeleton-containing phenolic curing agent (DIC Corporation, hydroxyl group equivalent weight approximately 151 g / eq., 1-methoxy-2-propanol solution with 50% non-volatile content) "V-03": Carbodiimide resin (manufactured by Nisshinbo Chemical, carbodiimide group equivalent weight 216 g / eq., toluene solution with 50% non-volatile components) "BA230S75": Bisphenol A dicyanate prepolymer (manufactured by Lonza Japan, cyanate group equivalent weight approximately 235g / eq., MEK solution with 75% non-volatile components) "PT30": Phenol novolac type multifunctional cyanate ester resin (manufactured by Lonza Japan, cyanate group equivalent weight approximately 124g / eq.)

[0232] (C) Low-elasticity polymer: "c-1": Low elasticity polymer (c-1) synthesized in Synthesis Example 9, non-volatile component 50% by mass "c-2": Low elasticity polymer (c-2) synthesized in Synthesis Example 10, non-volatile component 50% by mass "c-3": Low elasticity polymer (c-3) synthesized in Synthesis Example 11, non-volatile component 50% by mass

[0233] (D) Inorganic filler: "SO-C2": Spherical silica (average particle size 0.5 μm, manufactured by Admatechs) surface-treated with an aminosilane coupling agent ("KBM573" manufactured by Shin-Etsu Chemical Co., Ltd.) "Alumina A": Spherical alumina (average particle size 1.0 μm) surface-treated with an aminosilane coupling agent ("KBM573" manufactured by Shin-Etsu Chemical Co., Ltd.)

[0234] (E) Polymerizable unsaturated resin: "OPE-2St 1200": Vinylbenzyl-modified polyphenylene ether (manufactured by Mitsubishi Gas Chemical Co., Ltd., toluene solution with a non-volatile content of 65%) "SLK-6895-T90": Bismaleimide resin (manufactured by Shin-Etsu Chemical Co., Ltd., maleimide group equivalent weight approximately 345 g / eq., toluene solution with 90% non-volatile components) "e-1": Maleimide resin (e-1) synthesized in Synthesis Example 12, non-volatile component 60% by mass

[0235] (F)Organic filler: "EXL2655": Organic filler (manufactured by DOW)

[0236] (G) Curing accelerator: "1B2PZ": 1-benzyl-2-phenylimidazole (manufactured by Shikoku Chemicals Corporation) "Co(acac)3": Cobalt(III) acetylacetonate (Tokyo Chemical Industry Co., Ltd.)

[0237] (2) Resin sheet manufacturing: As a support, a polyethylene terephthalate film ("Lumirror R80" manufactured by Toray Industries, Inc., thickness 38 μm, softening point 130°C) that had been subjected to a release treatment with an alkyd resin-based release agent ("AL-5" manufactured by Lintec Corporation) was prepared. The resin composition was uniformly applied to the support using a die coater so that the thickness of the resin composition layer after drying would be 50 μm, and the film was dried at 70°C to 100°C for 3 minutes to form a resin composition layer. Next, the rough surface of a polypropylene film ("Alphan MA-411" manufactured by Oji F-Tex Co., Ltd., thickness 15 μm) was attached as a protective film to the side of the resin composition layer that was not bonded to the support. This produced a resin sheet having a support, a resin composition layer, and a protective film in this order.

[0238] <Test Example 1: Measurement test of dielectric loss tangent Df> The protective film was peeled off from the resin sheet, and the resin composition layer was thermally cured by heating at 200°C for 90 minutes, after which the support was peeled off to obtain a cured product, which was then cut into a piece 2 mm wide and 80 mm long to obtain a test piece for evaluation.

[0239] The dielectric loss tangent of each test piece was measured by a cavity resonance perturbation method using a measuring device ("HP8362B" manufactured by Agilent Technologies) at a measurement frequency of 5.8 GHz and a measurement temperature of 23°C. Measurements were performed on three test pieces, and the average value was calculated. Based on this average value, the dielectric loss tangent was evaluated according to the following criteria.

[0240] Evaluation criteria for dielectric loss tangent Df: "Poor": The dissipation factor is greater than 0.005. "Good": Dielectric tangent is 0.005 or less and greater than 0.0045. "Excellent": Dielectric tangent is 0.0045 or less.

[0241] <Test Example 2: Warpage measurement test> The resin sheet from which the protective film had been peeled off was laminated over the entire surface of one side of a 12-inch silicon wafer (775 μm thick) using a batch-type vacuum pressure laminator (Nikko Materials Co., Ltd., two-stage build-up laminator "CVP700"). This lamination was performed so that the resin composition layer and the silicon wafer were bonded. The support of the resin sheet was peeled off to expose the resin composition layer. A resin sheet from which the protective film had been peeled off was similarly laminated on the surface of this exposed resin composition layer, and the support was peeled off, forming two resin composition layers (total thickness 100 μm) on one side of the 12-inch silicon wafer. The lamination was performed by reducing the pressure to 13 hPa or less for 30 seconds, followed by pressure bonding at 100°C and a pressure of 0.74 MPa for 30 seconds.

[0242] The sample was heated in an oven at 100°C for 30 minutes, followed by further heating at 200°C for 90 minutes to cure the resin composition layer, yielding a sample laminate having a layer structure of "silicon wafer / cured product layer." The amount of warpage of the resulting sample laminate was measured using a shadow moiré measurement device ("Thermoire AXP" manufactured by Akorometrix). Measurements were performed in accordance with the JEITA standard EDX-7311-24. Specifically, a virtual plane calculated using the least squares method for all data on the evaluation substrate surface (the surface of the cured product layer opposite the silicon wafer) in the measurement area was used as the reference plane. The difference between the minimum and maximum vertical heights from this reference plane to the evaluation substrate surface was calculated as the amount of warpage. The measured values ​​of the amount of warpage were evaluated according to the following criteria. A smaller amount of warpage indicates more effective suppression of warpage.

[0243] Warpage evaluation criteria: "Excellent": Warpage is between 0 μm and 2000 μm "Good": Warpage is greater than 2000 μm and less than 2500 μm "Poor": Warpage is 2500 μm or more

[0244] <Test Example 3: Chemical Resistance Evaluation Test> The protective film was peeled off from the resin sheet, and the resin composition layer was thermally cured by heating at 200°C for 90 minutes. The support was then peeled off to obtain a cured product for evaluation. This cured product for evaluation was cut into squares with 5 cm sides to obtain multiple test pieces G. The mass M0 of this test piece G was measured. Hereinafter, the measured mass M0 may be referred to as the "mass before chemical immersion test" M0.

[0245] Test piece G was immersed in a strong alkaline aqueous solution at 70°C for 1 hour. A 1% by mass potassium hydroxide aqueous solution was used as the strong alkaline aqueous solution. Test piece G was then removed from the strong alkaline aqueous solution, washed with distilled water, and dried in an oven at 130°C for 1 hour to obtain test piece G' after the chemical immersion test. The mass M1 of test piece G' after the chemical immersion test was measured. Hereinafter, the measured mass M1 may be referred to as the "mass after chemical immersion test" M1.

[0246] The mass loss rate (%) due to the chemical immersion test was calculated from the mass M0 before the chemical immersion test and the mass M1 after the chemical immersion test according to the following formula (M1). Mass reduction rate (%)={(M0-M1) / M0}×100 (M1) From the mass loss rate (%) obtained as described above, the chemical resistance was evaluated according to the following criteria.

[0247] Chemical resistance evaluation criteria: "Good": The mass loss rate (%) is less than 5% by mass. The portion dissolved in chemicals is sufficiently small, and the chemical resistance is excellent. "Poor": Mass loss rate (%) is 5% or more. A large portion has dissolved in chemicals, and chemical resistance is poor.

[0248] <Result> The results of the above-mentioned Examples and Comparative Examples are shown in Tables 1 to 3 below.

[0249] [Table 1]

[0250] [Table 2]

[0251] [Table 3]

Claims

1. (A) an epoxy resin, (B) a curing agent, (C) a low modulus polymer, and (D) an inorganic filler; (B) A resin composition, wherein the curing agent (B-1) comprises an active ester resin containing one or more skeletons selected from the group consisting of an aliphatic hydrocarbon skeleton having 4 or more carbon atoms, a polyalkyleneoxy skeleton, a polysiloxane skeleton, and a polycarbonate skeleton.

2. 2. The resin composition according to claim 1, wherein the component (B-1) contains an aryloxycarbonyl group which may have a methyl group or a hydroxy group.

3. 2. The resin composition according to claim 1, wherein the low elastic polymer (C) comprises one or more selected from the group consisting of a polybutadiene structure, a polycarbonate structure, a polyalkylene structure, a polyalkyleneoxy structure, a polysiloxane structure, a poly(meth)acrylate structure, a polyisoprene structure, a polyisobutylene structure, and a polystyrene structure.

4. The resin composition according to claim 1, wherein the amount of the inorganic filler (D) is 50% by mass or more relative to 100% by mass of the nonvolatile components of the resin composition.

5. The resin composition according to claim 1, wherein the low-elasticity polymer (D) has a weight-average molecular weight of greater than 5,000.

6. The resin composition according to claim 1 for forming an insulating layer.

7. A support and a resin composition layer provided on the support, A resin sheet, wherein the resin composition layer comprises the resin composition according to any one of claims 1 to 6.

8. A cured product of the resin composition according to any one of claims 1 to 6.

9. A circuit board comprising a cured product of the resin composition according to any one of claims 1 to 6.

10. A semiconductor device comprising the circuit board according to claim 9.

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