Resin sheet

Abstract

To provide a resin sheet capable of suppressing the occurrence of unevenness after lamination and suppressing warpage after curing.SOLUTION: A resin sheet includes a support and a resin composition layer provided on the support, wherein the resin composition layer contains (A) an epoxy resin, (B) an organic solvent, (C) an inorganic filler, and (D) a stress relaxation material, and the component (B) contains an organic solvent having a boiling point of 120 °C or higher and lower than 220 °C, A content of toluene in the component (B) is 0% by mass to 9% by mass based on 100% by mass of the component (B), a content of an organic solvent having a boiling point of lower than 120 °C in the component (B) is 0% by mass to 30% by mass based on 100% by mass of the component (B), and a content of the epoxy resin (A) in the resin composition layer is 8.6% by mass or less based on 100% by mass of a non-volatile component in the resin composition layer; A content of the (C) component in the resin composition layer is 73.4% by mass or more on a basis of 100% by mass of non-volatile components in the resin composition layer.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a resin sheet having a resin composition (layer) containing an epoxy resin and an inorganic filler. [Background technology]

[0002] A known manufacturing technique for printed wiring boards is the build-up method, in which insulating layers and conductor layers are alternately stacked. In build-up manufacturing methods, the insulating layers are generally formed by curing a resin composition. In recent years, there has been a demand for lowering the dielectric loss tangent of the insulating layer.

[0003] It has been known that the dielectric loss tangent of an insulating layer can be reduced by using an epoxy resin composition containing an inorganic filler as the resin composition for forming the insulating layer, and that warping of the resin composition after curing can be suppressed by adding a stress relaxation material (Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6809014 Summary of the Invention [Problem to be solved by the invention]

[0005] However, when using an epoxy resin composition containing a stress relaxation material or inorganic filler, the stress relaxation material has poor compatibility with the epoxy resin composition, and the inorganic filler increases the melt viscosity, which can lead to issues with unevenness after lamination (see Test Example 4 for details on unevenness after lamination).

[0006] An object of the present invention is to provide a resin sheet that can suppress the occurrence of unevenness after lamination and warping after curing. [Means for solving the problem]

[0007] In order to achieve the objects of the present invention, the present inventors conducted extensive research and unexpectedly found that by using a resin sheet having a resin composition (layer) comprising (A) an epoxy resin, (B) an organic solvent, (C) an inorganic filler, and (D) a stress relaxation material, in which the content of aromatic solvents having a boiling point of less than 120°C in component (B) is 0% by mass to 9% by mass, assuming that the total amount of component (B) is 100% by mass, it is possible to suppress the occurrence of unevenness after lamination and warping after curing, and have completed the present invention.

[0008] That is, the present invention includes the following. [1] A resin sheet having a support and a resin composition layer provided on the support, the resin composition layer contains (A) an epoxy resin, (B) an organic solvent, (C) an inorganic filler, and (D) a stress relaxation material; A resin sheet in which the content of aromatic solvents having a boiling point of less than 120°C in component (B) is 0% by mass to 9% by mass, where the total amount of component (B) is 100% by mass. [2] The resin sheet according to the above [1], wherein the content of the component (D) in the resin composition layer is 1% by mass or more, when the non-volatile components in the resin composition layer are 100% by mass. [3] The resin sheet according to [1] or [2] above, wherein the content of the component (C) in the resin composition layer is 60% by mass or more, when the non-volatile components in the resin composition layer are 100% by mass. [4] The content (mass%) of component (C) when the nonvolatile components in the resin composition layer are taken as 100 mass%, and the specific surface area (m 2 The resin sheet according to any one of the above [1] to [3], wherein the product of the value of (a) and (b) is 300 or more. [5] The resin sheet according to any one of the above [1] to [4], wherein the content of the organic solvent having a boiling point of less than 120°C in the component (B) is 0% by mass to 30% by mass, when the total amount of the component (B) is 100% by mass. [6] The resin sheet according to any one of the above [1] to [5], wherein the content of the organic solvent having a boiling point of 220°C or higher in the component (B) is 0% by mass to 10% by mass, where the total amount of the component (B) is 100% by mass. [7] The resin sheet according to any one of the above [1] to [6], wherein the content of the aromatic solvent in the component (B) is 0% by mass to 9% by mass, where the total amount of the component (B) is 100% by mass. [8] The resin sheet according to any one of the above [1] to [7], wherein the content of the organic solvent having a boiling point of 120°C or more and less than 220°C in the component (B) is 85% by mass or more, when the total amount of the component (B) is 100% by mass. [9] The resin sheet according to any one of the above [1] to [8], wherein the component (D) comprises a non-particulate stress relaxation material containing a resin having one or more structures selected from a polybutadiene structure and a polycarbonate structure.

[10] The resin sheet according to any one of the above [1] to [9], wherein the component (D) contains a particulate stress relaxation material.

[11] The resin sheet according to

[10] above, wherein the particulate stress relaxation material has an average particle size of 10,000 nm or less.

[12] The resin sheet according to any one of the above [1] to

[11] , wherein the resin composition layer further contains (E) a curing agent.

[13] The resin sheet according to the above

[12] , wherein the component (E) contains one or more curing agents selected from an active ester curing agent and a carbodiimide curing agent.

[14] The resin sheet according to the above

[13] , wherein the component (E) contains an active ester-based curing agent.

[15] The resin sheet according to any one of the above [1] to

[14] , wherein the resin composition layer further contains (F) a curing accelerator.

[16] The resin sheet according to any one of the above [1] to

[15] , wherein the resin composition layer further contains (G) a radically polymerizable compound.

[17] The resin sheet according to the above

[16] , wherein the component (G) has a maleimide group.

[18] The resin sheet according to any one of the above [1] to

[17] , wherein the weight loss rate of the resin composition layer after the surface not in contact with the support is exposed to the outside air and heat-treated at 190°C for 30 minutes is 1% by mass to 10% by mass.

[19] The resin sheet according to any one of the above [1] to

[18] , wherein the resin composition layer has a dielectric loss tangent (Df) of 0.0090 or less after curing when measured at 10 GHz and 23°C.

[20] The resin sheet according to any one of the above [1] to

[19] , wherein the resin composition layer has a melt viscosity at 100°C of 50,000 poise or less.

[21] A method for producing a printed wiring board, comprising the following steps (I) and (II): (I) A step of laminating the resin sheet according to any one of the above [1] to

[20] so that the resin composition layer of the resin sheet is bonded to an inner layer substrate. (II) Step of curing the resin composition layer to form an insulating layer

[22] (A) an epoxy resin; (B) an organic solvent; (C) an inorganic filler; and (D) a stress relief material; A resin composition in which the content of aromatic solvents having a boiling point of less than 120°C in component (B) is 0 to 9% by mass, when the total amount of component (B) is 100% by mass. [Effects of the Invention]

[0009] According to the resin sheet of the present invention, it is possible to suppress the occurrence of unevenness after lamination and to suppress warping after curing. DETAILED DESCRIPTION OF THE INVENTION

[0010] The present invention will be described in detail below with reference to preferred embodiments thereof. However, the present invention is not limited to the following embodiments and examples, and can be implemented with any modifications within the scope of the claims of the present invention and their equivalents.

[0011] <Resin sheet> The resin sheet of the present invention has a support and a resin composition (layer) provided on the support.

[0012] <Resin composition (layer)> The thickness of the resin composition (layer) in the resin sheet of the present invention is not particularly limited, but from the viewpoint of thinning, it is preferably 250 μm or less, more preferably 200 μm or less, even more preferably 150 μm or less, and particularly preferably 100 μm or less. The lower limit of the thickness of the resin composition (layer) is not particularly limited, but it can be, for example, 5 μm or more, 10 μm or more, etc.

[0013] The resin composition (layer) in the resin sheet of the present invention contains (A) an epoxy resin, (B) an organic solvent, (C) an inorganic filler, and (D) a stress relaxation material, and the content of aromatic solvents having a boiling point of less than 120°C in component (B) is 0% to 9% by mass, assuming that the total amount of component (B) is 100% by mass. By using such a resin sheet, it is possible to prevent unevenness after lamination and warpage after curing.

[0014] The resin composition (layer) in the resin sheet of the present invention may contain optional components in addition to (A) epoxy resin, (B) organic solvent, (C) inorganic filler, and (D) stress relaxation material. Examples of optional components include (E) curing agent, (F) curing accelerator, (G) radical polymerizable compound, (H) thermoplastic resin, and (I) other additives. Each component contained in the resin composition (layer) in the resin sheet of the present invention will be described in detail below.

[0015] <(A) Epoxy resin> The resin composition (layer) in the resin sheet of the present invention contains (A) an epoxy resin, which is a curable resin having an epoxy group.

[0016] Examples of (A) epoxy resins include bixylenol-type epoxy resins, bisphenol A-type epoxy resins, bisphenol F-type epoxy resins, bisphenol S-type epoxy resins, bisphenol AF-type epoxy resins, dicyclopentadiene-type epoxy resins, trisphenol-type epoxy resins, naphthol novolac-type epoxy resins, phenol novolac-type epoxy resins, tert-butyl-catechol-type epoxy resins, naphthalene-type epoxy resins, naphthol-type epoxy resins, anthracene-type epoxy resins, glycidylamine-type epoxy resins, glycidyl ester-type epoxy resins, cresol novolac-type epoxy resins, 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. The (A) epoxy resin may be used alone or in combination of two or more.

[0017] The resin composition (layer) in the resin sheet of the present invention preferably contains, as the (A) epoxy resin, an epoxy resin having two or more epoxy groups per molecule. 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 particularly preferably 70% by mass or more.

[0018] Epoxy resins include epoxy resins that are liquid at a temperature of 20°C (hereinafter sometimes referred to as "liquid epoxy resins") and epoxy resins that are solid at a temperature of 20°C (hereinafter sometimes referred to as "solid epoxy resins"). The resin composition (layer) in the resin sheet of the present invention may contain only a liquid epoxy resin as the epoxy resin, or only a solid epoxy resin, or may contain both a liquid epoxy resin and a solid epoxy resin, but it is preferable that the resin composition (layer) contain both a liquid epoxy resin and a solid epoxy resin.

[0019] The liquid epoxy resin is preferably a liquid epoxy resin having two or more epoxy groups in one molecule.

[0020] Preferred liquid epoxy resins include glycerol-type epoxy resins, bisphenol A-type epoxy resins, bisphenol F-type epoxy resins, bisphenol AF-type epoxy resins, naphthalene-type epoxy resins, glycidyl ester-type epoxy resins, glycidyl amine-type epoxy resins, phenol novolac-type epoxy resins, alicyclic epoxy resins having an ester skeleton, cyclohexanedimethanol-type epoxy resins, alicyclic glycidyl ethers, and epoxy resins having a butadiene structure.

[0021] Specific examples of liquid epoxy resins include "EX-992L" manufactured by Nagase ChemteX Corporation, "YX7400" manufactured by Mitsubishi Chemical Corporation, "HP4032", "HP4032D", and "HP4032SS" (naphthalene-type epoxy resins) manufactured by DIC Corporation; "828US", "828EL", "825", and "Epikote 828EL" (bisphenol A-type epoxy resins) manufactured by Mitsubishi Chemical Corporation; and "jER807" and "1750" (bisphenol F-type epoxy resins) manufactured by Mitsubishi Chemical Corporation. epoxy resin); Mitsubishi Chemical Corporation's "jER152" (phenol novolac type epoxy resin); Mitsubishi Chemical Corporation's "630", "630LSD", and "604" (glycidylamine type epoxy resin); ADEKA Corporation's "ED-523T" (glycirol type epoxy resin); ADEKA Corporation's "EP-3950L" and "EP-3980S" (glycidylamine type epoxy resin); ADEKA Corporation's "EP-4088S" (dicyclopentadiene type epoxy resin); Nippon Steel Chemical & Material Corporation's "ZX1059" (mixture of bisphenol A type epoxy resin and bisphenol F type epoxy resin); Nagase ChemteX Corporation's "EX-721" (glycidyl ester type epoxy resin); Nagase ChemteX Corporation's "EX-991L" (epoxy resin containing alkyleneoxy and butadiene skeletons); Daicel Corporation's "Celloxide 2021P" (alicyclic epoxy resin with ester skeleton); Daicel Corporation's Examples include "PB-3600," "JP-100," "JP-200," and "JP-400" (epoxy resins having a butadiene structure) manufactured by Nippon Soda Co., Ltd.; "ZX1658" and "ZX1658GS" (liquid 1,4-glycidylcyclohexane-type epoxy resins) manufactured by Nippon Steel Chemical & Material Co., Ltd.; "EG-280" (fluorene structure-containing epoxy resin) manufactured by Osaka Gas Chemicals Co., Ltd.; and "EX-201" (cyclic aliphatic glycidyl ether) manufactured by Nagase ChemteX Corporation.

[0022] As the solid epoxy resin, a solid epoxy resin having three or more epoxy groups in one molecule is preferred, and an aromatic solid epoxy resin having three or more epoxy groups in one molecule is more preferred.

[0023] Preferred solid epoxy resins include bixylenol-type epoxy resins, naphthalene-type epoxy resins, naphthalene-type tetrafunctional epoxy resins, naphthol novolac-type epoxy resins, cresol novolac-type epoxy resins, dicyclopentadiene-type epoxy resins, trisphenol-type epoxy resins, naphthol-type epoxy resins, biphenyl-type epoxy resins, naphthylene ether-type epoxy resins, anthracene-type epoxy resins, bisphenol A-type epoxy resins, bisphenol AF-type epoxy resins, phenol aralkyl-type epoxy resins, tetraphenylethane-type epoxy resins, and phenolphthalimidine-type epoxy resins.

[0024] Specific examples of solid epoxy resins include "HP4032H" (naphthalene type epoxy resin) manufactured by DIC Corporation; "HP-4700" and "HP-4710" (naphthalene type tetrafunctional epoxy resins) manufactured by DIC Corporation; "N-690" (cresol novolac type epoxy resin) manufactured by DIC Corporation; "N-695" (cresol novolac type epoxy resin) manufactured by DIC Corporation; "HP-7200", "HP-7200HH", "HP-7200H", and "HP-7200L" (dicyclopentadiene type epoxy resins) manufactured by DIC Corporation; and "EXA-7311" and "E" manufactured by DIC Corporation. XA-7311-G3, EXA-7311-G4, EXA-7311-G4S, HP6000, HP6000L (naphthylene ether type epoxy resin); Nippon Kayaku Co., Ltd.'s "EPPN-502H" (trisphenol type epoxy resin); Nippon Kayaku Co., Ltd.'s "NC7000L" (naphthol novolac type epoxy resin); Nippon Kayaku Co., Ltd.'s "NC3000H", "NC3000", "NC3000L", "NC3000FH", "NC3100" (biphenyl type epoxy resin); Nippon Steel Chemical & Material Co., Ltd.'s "ESN475V", "ESN4100V" (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. Examples include "YX7700" (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.These may be used alone or in combination of two or more.

[0025] When a solid epoxy resin and a liquid epoxy resin are used in combination as the (A) epoxy resin, the mass ratio thereof (solid epoxy resin:liquid epoxy resin) is preferably 10:1 to 1:50, more preferably 2:1 to 1:20, and particularly preferably 1:1 to 1:10.

[0026] The epoxy equivalent of the (A) epoxy resin is preferably 50 g / eq. to 5,000 g / eq., more preferably 60 g / eq. to 2,000 g / eq., even more preferably 70 g / eq. to 1,000 g / eq., and even more preferably 80 g / eq. to 500 g / eq. The epoxy equivalent is the mass of the resin per equivalent of epoxy groups. This epoxy equivalent can be measured according to JIS K7236.

[0027] The weight average molecular weight (Mw) of the (A) epoxy resin is preferably 100 to 5,000, more preferably 250 to 3,000, and even more preferably 400 to 1,500. The weight average molecular weight of the resin can be measured by gel permeation chromatography (GPC) as a polystyrene-equivalent value.

[0028] The content of the (A) epoxy resin in the resin composition (layer) is not particularly limited, but is preferably 30% by mass or less, more preferably 25% by mass or less, even more preferably 20% by mass or less, even more preferably 15% by mass or less, and particularly preferably 10% by mass or less, based on 100% by mass of the nonvolatile components in the resin composition (layer). The lower limit of the content of the (A) epoxy resin in the resin composition (layer) is not particularly limited, but is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, even more preferably 1% by mass or more, even more preferably 3% by mass or more, and particularly preferably 5% by mass or more, based on 100% by mass of the nonvolatile components in the resin composition (layer).

[0029] <(B) Organic solvent> The resin composition (layer) in the resin sheet of the present invention contains a (B) organic solvent. The (B) organic solvent described here is a liquid compound (a compound that is liquid at room temperature (25°C)) with a boiling point of 250°C or less, which does not contain carbon-carbon double bonds or carbon-carbon triple bonds (excluding bonds that constitute aromatic rings) in the molecule composed of skeletal atoms selected from carbon and oxygen atoms. The (B) organic solvent described here does not include those that fall under the category of (A) epoxy resin. In this specification, the boiling point refers to the boiling point under normal pressure (1 atm; 760 mmHg) (i.e., the normal boiling point). The (B) organic solvent may be used alone or in combination of two or more.

[0030] (B) The organic solvent includes aromatic solvents and non-aromatic solvents.

[0031] Aromatic solvents are solvents that contain an aromatic ring in the molecule. Examples of aromatic solvents include C benzene (boiling point 80°C), toluene (boiling point 110°C), o-xylene (boiling point 144°C), m-xylene (boiling point 139°C), p-xylene (boiling point 138°C), and ethylbenzene (boiling point 136°C). 6-8 C9 aromatic hydrocarbons such as 1,2,3-trimethylbenzene (boiling point 176°C), 1,3,5-trimethylbenzene (boiling point 165°C), 1,2,4-trimethylbenzene (boiling point 169°C), 4-ethyltoluene (boiling point 161°C), 3-ethyltoluene (boiling point 160°C), and 2-ethyltoluene (boiling point 166°C); C9 aromatic hydrocarbons such as 1,2-diethylbenzene (boiling point 184°C), 1,3-diethylbenzene (boiling point 181°C), 1,4-diethylbenzene (boiling point 183°C), 3-ethyl-o-xylene (boiling point 194°C), 4-ethyl-o-xylene (boiling point 190°C), 2-ethyl-p-xylene (boiling point 187°C), and 1,2,3,5-tetramethylbenzene (boiling point 198°C). 10Examples of suitable aromatic hydrocarbon solvents include aromatic hydrocarbons; aromatic ketone solvents such as acetophenone (boiling point 202°C); aromatic alcohol solvents such as benzyl alcohol (boiling point 205°C) and phenethyl alcohol (boiling point 219-221°C); aromatic ether solvents such as anisole (boiling point 154°C) and phenetole (boiling point 169°C); and aromatic ester solvents such as methyl benzoate (boiling point 198-200°C) and ethyl benzoate (boiling point 211-213°C).

[0032] Non-aromatic solvents are solvents that do not contain an aromatic ring in the molecule, and examples of non-aromatic solvents include glycol-based solvents, glycol ether-based solvents, glycol ether ester-based solvents, aliphatic hydrocarbon-based solvents, aliphatic ketone-based solvents, aliphatic alcohol-based solvents, aliphatic ester-based solvents, and aliphatic ether-based solvents.

[0033] Examples of glycol-based solvents include ethylene glycol (boiling point 197°C), diethylene glycol (boiling point 244°C), propylene glycol (boiling point 188°C), dipropylene glycol (boiling point 232°C), and trimethylene glycol (boiling point 211-217°C).

[0034] Examples of glycol ether solvents include cellosolves such as ethylene glycol monomethyl ether (also known as methyl cellosolve) (boiling point 124°C), ethylene glycol monoethyl ether (also known as cellosolve) (boiling point 135°C), ethylene glycol monopropyl ether (also known as propyl cellosolve) (boiling point 151°C), ethylene glycol monobutyl ether (also known as butyl cellosolve) (boiling point 171°C), ethylene glycol monoisobutyl ether (also known as isobutyl cellosolve) (boiling point 160°C), ethylene glycol mono-tert-butyl ether (also known as tert-butyl cellosolve) (boiling point 152°C), and ethylene glycol monohexyl ether (boiling point 208°C); diethylene glycol monomethyl ether (also known as methyl carbitol) (boiling point 193°C), and diethylene glycol monoethyl ether (also known as carbitol) (boiling point 196°C). carbitols such as diethylene glycol monopropyl ether (also known as propyl carbitol) (boiling point 212-216°C), diethylene glycol monobutyl ether (DB) (also known as butyl carbitol) (boiling point 230°C); propylene glycol ethers such as propylene glycol monomethyl ether (PGM) (boiling point 120°C), propylene glycol monoethyl ether (boiling point 132°C), propylene glycol monopropyl ether (boiling point 150°C), and propylene glycol monobutyl ether (boiling point 170°C); dipropylene glycol ethers such as dipropylene glycol monomethyl ether (boiling point 188°C), dipropylene glycol monoethyl ether (boiling point 198°C), dipropylene glycol monopropyl ether (boiling point 210°C), and dipropylene glycol monobutyl ether (boiling point 215°C).

[0035] Examples of glycol ether ester solvents include cellosolve esters such as ethylene glycol monomethyl ether acetate (also known as methyl cellosolve acetate) (boiling point 145°C), ethylene glycol monoethyl ether acetate (also known as cellosolve acetate) (boiling point 156°C), and ethylene glycol monobutyl ether acetate (also known as butyl cellosolve acetate) (boiling point 191°C); diethylene glycol monoethyl ether acetate (EDGAC) (also known as carbitol acetate) ( carbitol esters such as diethylene glycol monobutyl ether acetate (also known as butyl carbitol acetate) (boiling point 217°C) and diethylene glycol monobutyl ether acetate (boiling point 247°C); propylene glycol ether esters such as propylene glycol monomethyl ether acetate (PGMEA) (boiling point 146°C) and propylene glycol monoethyl ether acetate (boiling point 160°C); and dipropylene glycol ether esters such as dipropylene glycol monomethyl ether acetate (boiling point 200°C).

[0036] Examples of aliphatic hydrocarbon solvents include n-pentane (boiling point 36°C), n-hexane (boiling point 69°C), 2-methylpentane (also known as isohexane) (boiling point 60-62°C), n-heptane (boiling point 98°C), n-octane (boiling point 125°C), cyclopentane (boiling point 49°C), cyclohexane (boiling point 81°C), methylcyclohexane (boiling point 101°C), and ethylcyclohexane (boiling point 132°C).

[0037] Examples of aliphatic ketone solvents include acyclic ketones such as acetone (boiling point 56°C), methyl ethyl ketone (MEK) (boiling point 79°C), diethyl ketone (boiling point 101°C), 2-pentanone (boiling point 101°C), methyl isobutyl ketone (boiling point 116°C), 2-hexanone (boiling point 127°C), 2-heptanone (MAK) (boiling point 151°C), and diisobutyl ketone (boiling point 168°C); and cyclic ketones such as cyclohexanone (boiling point 155°C) and 2-methylcyclohexanone (boiling point 162°C).

[0038] Examples of aliphatic alcohol solvents include methanol (boiling point 64°C), ethanol (boiling point 78°C), n-propanol (boiling point 97°C), isopropanol (boiling point 82°C), n-butyl alcohol (boiling point 117°C), isobutyl alcohol (boiling point 108°C), sec-butyl alcohol (boiling point 99°C), tert-butyl alcohol (boiling point 82°C), n-pentyl alcohol (boiling point 138°C), and isopentyl alcohol (boiling point 131°C). ), sec-pentyl alcohol (boiling point 119°C), tert-pentyl alcohol (boiling point 102°C), neopentyl alcohol (boiling point 113°C), n-hexyl alcohol (boiling point 157°C), n-heptyl alcohol (boiling point 175°C), isoheptyl alcohol (boiling point 159°C), n-octyl alcohol (boiling point 195°C), 2-ethylhexyl alcohol (boiling point 184°C), cyclohexanol (boiling point 161°C), and the like.

[0039] Examples of aliphatic ester solvents include methyl acetate (boiling point 57°C), ethyl acetate (boiling point 77°C), n-propyl acetate (boiling point 96°C), isopropyl acetate (boiling point 89°C), n-butyl acetate (boiling point 126°C), isobutyl acetate (boiling point 118°C), sec-butyl acetate (boiling point 112°C), tert-butyl acetate (boiling point 97°C), n-pentyl acetate (boiling point 149°C), isopentyl acetate (boiling point 142°C), ethyl propionate (boiling point 99°C), and propionate. Examples of suitable alkyl esters include fatty acid alkyl esters such as propyl lactate (boiling point 122°C) and isopropyl propionate (boiling point 108°C); hydroxy acid alkyl esters such as methyl lactate (boiling point 144-145°C), ethyl lactate (boiling point 151-155°C), and butyl lactate (boiling point 185-187°C); keto acid alkyl esters such as methyl acetoacetate (boiling point 170°C) and ethyl acetoacetate (boiling point 184°C); and lactones such as γ-butyrolactone (boiling point 204°C).

[0040] Examples of aliphatic ether solvents include diethyl ether (boiling point 34°C), diisopropyl ether (boiling point 68°C), methyl tert-butyl ether (boiling point 55°C), tetrahydrofuran (boiling point 66°C), 1,4-dioxane (boiling point 101°C), and 1,3-dioxolane (boiling point 75°C).

[0041] The content of aromatic solvents having a boiling point of less than 120°C in the (B) organic solvent contained in the resin composition (layer) is 0% by mass to 9% by mass, where the total amount of the (B) organic solvents contained in the resin composition (layer) is 100% by mass. From the viewpoint of further reducing the dielectric tangent and further suppressing warpage, the content is preferably 0% by mass to 7% by mass, more preferably 0% by mass to 5% by mass, even more preferably 0% by mass to 3% by mass, even more preferably 0% by mass to 1% by mass, and particularly preferably 0% by mass to 0.1% by mass.

[0042] From the viewpoint of further suppressing the occurrence of unevenness, the content of the aromatic solvent in the (B) organic solvent contained in the resin composition (layer) is preferably 0% by mass to 9% by mass, more preferably 0% by mass to 7% by mass, even more preferably 0% by mass to 5% by mass, even more preferably 0% by mass to 3% by mass, still more preferably 0% by mass to 1% by mass, and particularly preferably 0% by mass to 0.1% by mass, where the total (B) organic solvent contained in the resin composition (layer) is taken as 100% by mass.

[0043] From the viewpoint of significantly obtaining the effects of the present invention, the content of the organic solvent having a boiling point of less than 120°C in the (B) organic solvent contained in the resin composition (layer) is preferably 0% by mass to 50% by mass, more preferably 0% by mass to 40% by mass, even more preferably 0% by mass to 30% by mass, still more preferably 0% by mass to 20% by mass, and particularly preferably 0% by mass to 15% by mass, when the total (B) organic solvent contained in the resin composition (layer) is taken as 100% by mass.

[0044] From the viewpoint of significantly obtaining the effects of the present invention, the content of the organic solvent having a boiling point of 120°C or more and less than 220°C in the (B) organic solvent contained in the resin composition (layer) is preferably 50% by mass or more, more preferably 60% by mass or more, even more preferably 70% by mass or more, still more preferably 80% by mass or more, and particularly preferably 85% by mass or more, when the total amount of the (B) organic solvent contained in the resin composition (layer) is taken as 100% by mass.

[0045] The content of the organic solvent having a boiling point of 220°C or higher in the (B) organic solvent contained in the resin composition (layer), when the total amount of the (B) organic solvent contained in the resin composition (layer) is taken as 100% by mass, is preferably 0% by mass to 25% by mass, more preferably 0% by mass to 20% by mass, even more preferably 0% by mass to 15% by mass, even more preferably 0% by mass to 10% by mass, still more preferably 0% by mass to 5% by mass, particularly preferably 0% by mass to 1% by mass, and especially preferably 0% by mass to 0.1% by mass, from the viewpoint of further reducing the dielectric tangent and further suppressing warping.

[0046] The content of (B) organic solvent in the resin composition (layer) is not particularly limited, but is preferably 10% by mass or less, more preferably 8% by mass or less, even more preferably 6% by mass or less, and particularly preferably 5% by mass or less, from the viewpoint of further reducing the dielectric loss tangent (Df) and further suppressing the occurrence of warping, when all components in the resin composition (layer) are taken as 100% by mass. From the viewpoint of achieving better lamination properties, the lower limit of the content of (B) organic solvent in the resin composition (layer) is preferably 0.1% by mass or more, more preferably 0.2% by mass or more, even more preferably 0.5% by mass or more, and particularly preferably 1% by mass or more, when all components in the resin composition (layer) are taken as 100% by mass.

[0047] The content of the (B) organic solvent in the resin composition (layer) can be set so that the weight loss rate of the resin composition layer after the surface of the resin sheet not in contact with the support is exposed to the outside air and heat-treated at 190°C (under normal pressure) for 30 minutes is preferably 10% by mass or less, more preferably 9% by mass or less, even more preferably 8% by mass or less, and particularly preferably 7% by mass or less, from the viewpoint of further reducing the dielectric loss tangent (Df) and further suppressing the occurrence of warping; and the lower limit thereof is preferably 1% by mass or more, more preferably 1.4% by mass or more, even more preferably 1.6% by mass or more, and particularly preferably 1.8% by mass or more, from the viewpoint of achieving better lamination properties.

[0048] <(C) Inorganic filler> The resin composition (layer) in the resin sheet of the present invention contains an inorganic filler (C). The inorganic filler (C) is contained in the resin composition (layer) in the form of particles.

[0049] (C) Inorganic fillers are inorganic compounds. Examples of (C) 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 is particularly preferred. Examples of silica include amorphous silica, fused silica, crystalline silica, synthetic silica, and hollow silica. Spherical silica is preferred. The (C) inorganic filler may be used alone or in combination of two or more kinds in any ratio.

[0050] (C) Examples of commercially available inorganic fillers include "SP60-05" and "SP507-05" manufactured by Nippon Steel Chemical & Material Co., Ltd.; "YC100C", "YA050C", "YA050C-MJE", and "YA010C" manufactured by Admatechs Co., Ltd.; "UFP-30" manufactured by Denka Company Limited; "Silfill NSS-3N", "Silfill NSS-4N", and "Silfill NSS-5N" manufactured by Tokuyama Corporation; "SC2500SQ", "SO-C4", "SO-C2", and "SO-C1" manufactured by Admatechs Co., Ltd.; and "DAW-03" and "FB-105FD" manufactured by Denka Company Limited.

[0051] The average particle size of the (C) inorganic filler is not particularly limited, but is preferably 10 μm or less, more preferably 5 μm or less, even more preferably 3 μm or less, even more preferably 2 μm or less, and particularly preferably 1.5 μm or less. The lower limit of the average particle size of the (C) inorganic filler is not particularly limited, but is preferably 0.01 μm or more, more preferably 0.05 μm or more, even more preferably 0.1 μm or more, and particularly preferably 0.2 μm or more. The average particle size of the (C) inorganic filler can be measured by a laser diffraction / scattering method based on Mie scattering theory. Specifically, a particle size distribution of the inorganic filler is created on a volume basis using a laser diffraction / scattering particle size distribution analyzer, and the median diameter is used as the average particle size. A measurement sample can be prepared by weighing 100 mg of inorganic filler and 10 g of methyl ethyl ketone into a vial and ultrasonically dispersing for 10 minutes. The measurement sample was measured using a laser diffraction particle size distribution analyzer, with blue and red light source wavelengths used, and the particle size distribution of the inorganic filler on a volume basis was measured using a flow cell system, and the average particle size was calculated as the median diameter from the particle size distribution obtained. An example of a laser diffraction particle size distribution analyzer is the "LA-960" manufactured by Horiba, Ltd.

[0052] The specific surface area of ​​the (C) inorganic filler is not particularly limited, but is preferably 0.1 m 2 / g or more, more preferably 0.5m 2 / g or more, more preferably 1m 2 / g or more, particularly preferably 3m2 The upper limit of the specific surface area of ​​the inorganic filler (C) is not particularly limited, but is preferably 100 m 2 / g or less, more preferably 70m 2 / g or less, more preferably 50m 2 / g or less, and even more preferably 30m 2 / g or less, particularly preferably 10m 2 The specific surface area of ​​the inorganic filler is obtained by adsorbing nitrogen gas onto the surface of a sample using a specific surface area measuring device (Macsorb HM-1210 manufactured by Mountech Co., Ltd.) according to the BET method, and then calculating the specific surface area using the BET multipoint method.

[0053] The (C) 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. The surface treatment agent may be used alone or in any combination of two or more.

[0054] 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).

[0055] The degree of surface treatment with the surface treatment agent is preferably within a predetermined range from the viewpoint of improving the dispersibility of the inorganic filler. Specifically, 100% by mass of the inorganic filler is preferably surface-treated with 0.2% to 5% by mass of the surface treatment agent, more preferably 0.2% to 3% by mass, and even more preferably 0.3% to 2% by mass.

[0056] The degree of surface treatment with the surface treatment agent can be evaluated by the amount of carbon per unit surface area of ​​the inorganic filler. From the viewpoint of improving the dispersibility of the inorganic filler, the amount of carbon per unit surface area of ​​the inorganic filler is set to 0.02 mg / m 2 More than 0.1 mg / m is preferable. 2 More preferably, 0.2 mg / m or more 2 On the other hand, from the viewpoint of preventing an increase in the melt viscosity of the resin composition or the melt viscosity in the form of a sheet, it is more preferable that the melt viscosity is 1.0 mg / m 2 Less than 0.8 mg / m is preferred 2 Less than 0.5 mg / m is more preferable. 2 The following is even more preferred:

[0057] (C) The amount of carbon per unit surface area of ​​the inorganic filler can be measured after the surface-treated inorganic filler is washed with a solvent (e.g., methyl ethyl ketone (MEK)). Specifically, a sufficient amount of MEK as a solvent is added to the inorganic filler that has been surface-treated with a surface treatment agent, and ultrasonic cleaning is performed at 25°C for 5 minutes. After removing the supernatant and drying the 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.

[0058] The content of the (C) inorganic filler in the resin composition (layer) is not particularly limited, but is preferably 95% by mass or less, more preferably 90% by mass or less, even more preferably 85% by mass or less, and particularly preferably 80% by mass or less, when the nonvolatile components in the resin composition (layer) are taken as 100% by mass. The lower limit of the content of the (C) inorganic filler in the resin composition (layer) is not particularly limited, but from the viewpoint of further reducing the dielectric loss tangent, when the nonvolatile components in the resin composition (layer) are taken as 100% by mass, it is preferably 5% by mass or more, 10% by mass or more, more preferably 20% by mass or more, 30% by mass or more, even more preferably 40% by mass or more, 50% by mass or more, even more preferably 55% by mass or more, 60% by mass or more, and particularly preferably 65% ​​by mass or more, 70% by mass or more.

[0059] The content (mass%) of the (C) inorganic filler when the nonvolatile components in the resin composition (layer) are taken as 100 mass%, and the specific surface area (m 2 From the viewpoint of further suppressing warpage during curing and further reducing the dielectric loss tangent, the product of this value and the dielectric loss tangent ( / g) is preferably 230 or more, more preferably 250 or more, even more preferably 280 or more, and particularly preferably 300 or more.

[0060] <(D) Stress relief material> The resin composition (layer) in the resin sheet of the present invention contains a (D) stress relief material. The (D) stress relief material refers to a flexible resin and can be a particulate resin component (particulate stress relief material) that maintains its particle form in the resin composition (layer), or a non-particulate resin component (non-particulate stress relief material) that tends to be mixed with or dissolved in the resin composition (layer). Either one or both of these may be present, and the resin components forming them may be resins that exhibit rubber elasticity themselves or resins that exhibit rubber elasticity through reaction with other components. Examples of resins that exhibit rubber elasticity include resins that exhibit an elastic modulus of 1 GPa or less when subjected to a tensile test in accordance with Japanese Industrial Standards (JIS K7161) at 25°C and 40% RH.

[0061] The particulate stress relief material is preferably spherical. The particulate stress relief material may be hollow particles having voids inside the particles, or may be non-hollow particles having no voids inside the particles. The hollow particles may be monohollow particles having only one void inside the particles, or polyhollow particles having multiple voids inside the particles.

[0062] The particulate stress relief material is, for example, rubber particles containing a rubber component, and is preferably a rubber particle containing, as the rubber component, a silicone-based elastomer such as polydimethylsiloxane; an olefin-based thermoplastic elastomer 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-butadiene terpolymer, or ethylene-propylene-butene terpolymer; or an acrylic-based thermoplastic elastomer such as polypropyl(meth)acrylate, polybutyl(meth)acrylate, polycyclohexyl(meth)acrylate, or polyoctyl(meth)acrylate. Furthermore, a silicone-based rubber such as polyorganosiloxane rubber may be mixed with 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.

[0063] From the viewpoint of significantly achieving the desired effects of the present invention, the particulate stress relief material preferably contains core-shell rubber particles. Core-shell rubber particles are particulate stress relief materials consisting of core particles containing a rubber component such as those listed above, and one or more shell layers covering the core particles. Furthermore, the core-shell rubber particles are preferably core-shell graft copolymer rubber particles consisting of core particles containing a rubber component such as those listed above, and a shell formed by graft copolymerization of a monomer component copolymerizable with the rubber component contained in the core particles. The term "core-shell" as used herein 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 by the shell portion.

[0064] The rubber component is preferably contained in the core-shell rubber particles in an amount of 40% by mass or more, more preferably 50% by mass or more, and even more preferably 60% by mass or more. The upper limit of the rubber component content in the core-shell rubber particles is not particularly limited, but from the viewpoint of sufficiently covering the core particles with the shell portion, it is preferably 95% by mass or less, for example, 90% by mass or less.

[0065] The monomer components forming the shell of the core-shell rubber particles include, for example, (meth)acrylic acid esters such as methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, cyclohexyl (meth)acrylate, octyl (meth)acrylate, and glycidyl (meth)acrylate; (meth)acrylic acid; N-substituted maleimides such as N-methylmaleimide and N-phenylmaleimide; maleimide; α,β-unsaturated carboxylic acids such as maleic acid and itaconic acid; aromatic vinyl compounds such as styrene, 4-vinyltoluene, and α-methylstyrene; and (meth)acrylonitrile. Among these, (meth)acrylic acid esters are preferred, and methyl (meth)acrylate is more preferred. Note that "(meth)acrylic acid" refers to methacrylic acid or acrylic acid.

[0066] Commercially available core-shell rubber particles include, for example, "CHT" manufactured by Cheil Industries; "B602" manufactured by UMGABS; "Paraloid EXL-2602," "Paraloid EXL-2603," "Paraloid EXL-2655," "Paraloid EXL-2311," "Paraloid EXL-2313," "Paraloid EXL-2315," "Paraloid KM-330," and "Paraloid KM-336P" manufactured by Dow Chemical Japan. Examples include "Pararoid KCZ-201," "Metablen C-223A," "Metablen E-901," "Metablen S-2001," "Metablen W-450A," and "Metablen SRK-200" manufactured by Mitsubishi Rayon Co., Ltd., "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 "AC3401N" and "AC3816N" manufactured by Ganz Chemical Co., Ltd.

[0067] The average particle size (average primary particle size) of the particulate stress relief material is not particularly limited, but is preferably 20 nm or more, more preferably 30 nm or more, and even more preferably 50 nm or more. The upper limit of the average particle size (average primary particle size) of the particulate stress relief material is not particularly limited, but is preferably 10,000 nm or less, more preferably 5,000 nm or less, and even more preferably 1,000 nm or less. The average particle size (average primary particle size) of the particulate stress relief material can be measured using a zeta potential particle size distribution measuring device or the like.

[0068] The non-particulate stress relief material preferably contains a resin having one or more structures selected from a polybutadiene structure, a polysiloxane structure, a poly(meth)acrylate structure, a polyalkylene structure, a polyalkyleneoxy structure, a polyisoprene structure, a polyisobutylene structure, and a polycarbonate structure in its molecule, more preferably a resin having one or more structures selected from a polybutadiene structure and a polycarbonate structure, and particularly preferably a resin having a polybutadiene structure and a phenolic hydroxyl group (phenolic hydroxyl group-containing polybutadiene resin) or a resin having a polycarbonate structure (polycarbonate resin). Note that "(meth)acrylate" refers to methacrylate and acrylate.

[0069] The polybutadiene structure includes not only a structure formed by polymerizing butadiene but also a structure formed by hydrogenating the structure. The polybutadiene structure may be partially or entirely hydrogenated. Furthermore, the polybutadiene structure may be contained in the main chain or side chain of the stress relaxation material molecule.

[0070] Preferred examples of polybutadiene resins include hydrogenated polybutadiene skeleton-containing resins, hydroxy group-containing polybutadiene resins, phenolic hydroxyl 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, and urethane group-containing polybutadiene resins. Among these, phenolic hydroxyl group-containing polybutadiene resins and epoxy group-containing polybutadiene resins are more preferred, and phenolic hydroxyl group-containing polybutadiene resins are particularly preferred. Here, "hydrogenated polybutadiene skeleton-containing resin" refers to a resin in which at least a portion of the polybutadiene skeleton is hydrogenated, and does not necessarily have to be a resin in which the polybutadiene skeleton is completely hydrogenated. Examples of hydrogenated polybutadiene skeleton-containing resins include hydrogenated polybutadiene skeleton-containing epoxy resins. Examples of preferred phenolic hydroxyl group-containing polybutadiene resins include those made from hydroxyl group-terminated polybutadiene, diisocyanate compounds, and phenolic hydroxyl group-containing resins. Here, the hydroxyl group-terminated polybutadiene and diisocyanate compounds are the same as those exemplified below. Examples of phenolic hydroxyl group-containing resins include cresol novolac resins.

[0071] Specific examples of polybutadiene resins include "PB-3600" (epoxy group-containing polybutadiene) manufactured by Daicel Corporation, "JP-100" and "JP-200" (epoxy group-containing polybutadiene) manufactured by Nippon Soda Co., Ltd., and "Ricon 657" (epoxy group-containing polybutadiene), "Ricon 130MA8", "Ricon 130MA13", "Ricon 130MA20", "Ricon 131MA5", "Ricon 131MA10", "Ricon 131MA17", "Ricon 131MA20", and "Ricon Examples include "184MA6" (polybutadiene containing an acid anhydride group), "GQ-1000" (polybutadiene with introduced hydroxyl and carboxyl groups), "G-1000", "G-2000", and "G-3000" (polybutadiene with hydroxyl groups at both ends) manufactured by Nippon Soda Co., Ltd., "GI-1000", "GI-2000", and "GI-3000" (hydrogenated polybutadiene with hydroxyl groups at both ends) manufactured by Daicel Corporation, "PB3600" and "PB4700" (polybutadiene-based epoxy compounds), "Epofriend A1005", "Epofriend A1010", and "Epofriend A1020" (epoxy compounds of styrene, butadiene, and styrene block copolymers), and "FCA-061L" (hydrogenated polybutadiene-based epoxy compound) and "R-45EPT" (polybutadiene-based epoxy compound) manufactured by Nagase ChemteX Corporation.

[0072] Further, examples of preferred polybutadiene resins include linear polyimides (such as those described in JP 2006-37083 A and WO 2008 / 153208 A) made from hydroxyl-terminated polybutadiene, diisocyanate compounds, and polybasic acids or their anhydrides. The polyimide resin preferably has a polybutadiene structure content of 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.

[0073] The number average molecular weight of the hydroxyl group-terminated polybutadiene is preferably 500 to 5,000, more preferably 800 to 3,500. The hydroxyl group equivalent of the hydroxyl group-terminated polybutadiene is preferably 250 to 5,000 g / eq., more preferably 1,000 to 3,000 g / eq.

[0074] Examples of diisocyanate compounds include aromatic diisocyanates such as toluene-2,4-diisocyanate, toluene-2,6-diisocyanate, xylylene diisocyanate, and diphenylmethane diisocyanate; aliphatic diisocyanates such as hexamethylene diisocyanate; and alicyclic diisocyanates such as isophorone diisocyanate. Among these, aromatic diisocyanates are preferred, and toluene-2,4-diisocyanate is more preferred.

[0075] Examples of polybasic acids or anhydrides thereof include tetrabasic acids such as ethylene glycol bistrimellitic acid, pyromellitic acid, benzophenone tetracarboxylic acid, biphenyl tetracarboxylic acid, naphthalene tetracarboxylic acid, 5-(2,5-dioxotetrahydrofuryl)-3-methyl-cyclohexene-1,2-dicarboxylic acid, and 3,3'-4,4'-diphenylsulfone tetracarboxylic acid, and their anhydrides; tribasic acids such as trimellitic acid and cyclohexane tricarboxylic acid, and their anhydrides; and 1,3,3a,4,5,9b-hexahydro-5-(tetrahydro-2,5-dioxo-3-furanyl)-naphtho(1,2-C)furan-1,3-dione.

[0076] The polybutadiene resin may also contain a polystyrene structure obtained by polymerizing styrene.

[0077] Specific examples of polystyrene resins, which are resins having a polystyrene structure in the molecule, 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, and hydrogenated styrene-butadiene random copolymer.

[0078] Commercially available polystyrene resins may be used, including 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 elastomer having hydroxyl groups "Septon HG252" (manufactured by Kuraray Co., Ltd.); modified styrene-based elastomer having carboxyl groups "Tuftec N503M," modified styrene-based elastomer having amino groups "Tuftec N501," modified styrene-based elastomer having acid anhydride groups "Tuftec M1913" (manufactured by Asahi Kasei Chemicals Corporation); and unmodified styrene-based elastomer "Septon S8104" (manufactured by Kuraray Co., Ltd.). Component (C) may be used alone or in combination of two or more.

[0079] The polysiloxane structure is a structure containing a siloxane bond, and is contained in, for example, silicone rubber. The polysiloxane structure may be contained in the main chain or the side chain of the stress relaxation material molecule.

[0080] Specific examples of polysiloxane resins, which are resins having a polysiloxane structure in the molecule, include "SMP-2006," "SMP-2003PGMEA," and "SMP-5005PGMEA" manufactured by Shin-Etsu Silicones Co., Ltd., amine-terminated polysiloxanes, and linear polyimides made from tetrabasic acid anhydrides (WO 2010 / 053185).

[0081] The poly(meth)acrylate structure is a structure formed by polymerizing acrylic acid or an acrylic acid ester, and also includes a structure formed by polymerizing methacrylic acid or a methacrylic acid ester. The (meth)acrylate structure may be contained in the main chain or in the side chain of the stress relaxation material molecule.

[0082] Preferred examples of poly(meth)acrylate resins, which are resins having a poly(meth)acrylate structure in the molecule, include hydroxy group-containing poly(meth)acrylate resins, phenolic hydroxy group-containing poly(meth)acrylate resins, carboxy group-containing poly(meth)acrylate resins, acid anhydride group-containing poly(meth)acrylate resins, epoxy group-containing poly(meth)acrylate resins, isocyanate group-containing poly(meth)acrylate resins, and urethane group-containing poly(meth)acrylate resins.

[0083] Specific examples of poly(meth)acrylate resins include Nagase ChemteX's Teisan Resin "SG-70L," "SG-708-6," "WS-023," "SG-700AS," and "SG-280TEA" (carboxyl group-containing acrylic ester copolymer resin, acid value 5 to 34 mgKOH / g, weight average molecular weight 400,000 to 900,000, Tg -30°C to 5°C), "SG-80H," "SG-80H-3," and "SG-P3" (epoxy group-containing acrylic ester copolymer resin, epoxy equivalent 4761 to 14285 g / eq, weight average molecular weight 350,000). Examples include "SG-600TEA" and "SG-790" (hydroxy group-containing acrylic ester copolymer resin, hydroxyl value 20-40 mgKOH / g, weight average molecular weight 500,000-1,200,000, Tg -37°C to -32°C) manufactured by Negami Chemical Industrial Co., Ltd., as well as "ME-2000" and "W-116.3" (carboxy group-containing acrylic ester copolymer resin), "W-197C" (hydroxy group-containing acrylic ester copolymer resin), "KG-25" and "KG-3000" (epoxy group-containing acrylic ester copolymer resin).

[0084] The polyalkylene structure preferably has a predetermined number of carbon atoms. The specific number of carbon atoms in the polyalkylene structure is preferably 2 or more, more preferably 3 or more, particularly preferably 5 or more, and preferably 15 or less, more preferably 10 or less, particularly preferably 6 or less. The polyalkylene structure may be contained in the main chain or side chain of the stress relaxation material molecule.

[0085] The polyalkyleneoxy structure preferably has a predetermined number of carbon atoms. The specific number of carbon atoms in the polyalkyleneoxy structure is preferably 2 or more, preferably 3 or more, more preferably 5 or more, and preferably 15 or less, more preferably 10 or less, and particularly preferably 6 or less. The polyalkyleneoxy structure may be contained in the main chain or side chain of the stress relaxation material molecule.

[0086] Specific examples of polyalkylene resins, which are resins having a polyalkylene structure in the molecule, and polyalkyleneoxy resins, which are resins having a polyalkyleneoxy structure in the molecule, include "PTXG-1000" and "PTXG-1800" manufactured by Asahi Kasei Fibers Corporation, "YX-7180" (a resin containing an alkylene structure with an ether bond) manufactured by Mitsubishi Chemical Corporation, "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.

[0087] The polyisoprene structure may be contained in the main chain or side chain of the stress relaxation material molecule. Specific examples of polyisoprene resins that have a polyisoprene structure in the molecule include "KL-610" and "KL-613" manufactured by Kuraray Co., Ltd.

[0088] The polyisobutylene structure may be contained in the main chain or in a side chain of the stress relaxation material molecule. Specific examples of polyisobutylene resins, which are resins having a polyisobutylene structure in the molecule, include "SIBSTAR-073T" (styrene-isobutylene-styrene triblock copolymer) and "SIBSTAR-042D" (styrene-isobutylene diblock copolymer), both manufactured by Kaneka Corporation.

[0089] The polycarbonate structure may be contained in the main chain or in the side chain of the molecule of the stress relaxation material.

[0090] Preferred examples of polycarbonate resins, which are resins having a polycarbonate structure in the molecule, include hydroxy group-containing polycarbonate resins, phenolic hydroxy group-containing polycarbonate resins, carboxy group-containing polycarbonate resins, acid anhydride group-containing polycarbonate resins, epoxy group-containing polycarbonate resins, isocyanate group-containing polycarbonate resins, and urethane group-containing polycarbonate resins.

[0091] Specific examples of polycarbonate resins include "T6002" and "T6001" (polycarbonate diols) manufactured by Asahi Kasei Chemicals Corporation, and "C-1090", "C-2090", and "C-3090" (polycarbonate diols) manufactured by Kuraray Co., Ltd.

[0092] Preferred examples of polycarbonate resins include linear polyimides made from hydroxyl-terminated polycarbonates, diisocyanate compounds, and polybasic acids or their anhydrides. The linear polyimides have a urethane structure and a polycarbonate structure. The polycarbonate 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.

[0093] The number average molecular weight of the hydroxyl group-terminated polycarbonate is preferably 500 to 5,000, more preferably 1,000 to 3,000. The hydroxyl group equivalent of the hydroxyl group-terminated polycarbonate is preferably 250 to 1,250.

[0094] The non-particulate stress relief material preferably further has an imide structure, which can increase the heat resistance of the non-particulate stress relief material and effectively increase the crack resistance.

[0095] The non-particulate stress relaxation material may have any of a linear, branched, or cyclic structure, but is preferably linear.

[0096] The non-particulate stress relief material preferably further has a functional group capable of reacting with the epoxy resin. This functional group includes a reactive group that appears upon heating. The non-particulate stress relief material having a functional group can improve the mechanical strength of the cured resin composition (layer).

[0097] Examples of the functional group include a carboxy group, a hydroxy group, an acid anhydride group, a phenolic hydroxyl group, an epoxy group, an isocyanate group, and a urethane group. Among these, from the viewpoint of significantly achieving the effects of the present invention, the functional group preferably has one or more functional groups selected from a hydroxyl group, an acid anhydride group, a phenolic hydroxyl group, an epoxy group, an isocyanate group, and a urethane group, and a phenolic hydroxyl group is particularly preferred.

[0098] The non-particulate stress relaxation material may be used alone or in combination of two or more kinds.

[0099] The specific number average molecular weight Mn of the non-particulate stress relief material is preferably 500 or more, more preferably 800 or more, even more preferably 1,000 or more, particularly preferably 1,200 or more, and is preferably 100,000 or less, more preferably 50,000 or less, particularly preferably 10,000 or less. The number average molecular weight Mn of the non-particulate stress relief material is the number average molecular weight in terms of polystyrene measured using GPC (gel permeation chromatography).

[0100] When the non-particulate stress relief material has functional groups, the functional group equivalent of the non-particulate stress relief material is preferably 100 g / eq. or more, more preferably 200 g / eq. or more, even more preferably 1,000 g / eq. or more, particularly preferably 2,500 g / eq. or more, and preferably 50,000 g / eq. or less, more preferably 30,000 g / eq. or less, even more preferably 10,000 g / eq. or less, particularly preferably 5,000 g / eq. or less. The functional group equivalent is the number of grams of resin containing 1 gram equivalent of functional groups. For example, the epoxy group equivalent can be measured according to JIS K7236. Furthermore, for example, the hydroxyl group equivalent can be calculated by dividing the molecular weight of KOH by the hydroxyl value measured according to JIS K1557-1.

[0101] The glass transition temperature (Tg) of the (D) stress relaxation material is preferably 20°C or lower, more preferably 10°C or lower, and even more preferably 0°C or lower.

[0102] The content of (D) stress relaxation material in the resin composition (layer) is not particularly limited, but is preferably 50% by mass or less, more preferably 30% by mass or less, even more preferably 25% by mass or less, even more preferably 20% by mass or less, and particularly preferably 15% by mass or less, based on 100% by mass of the nonvolatile components in the resin composition (layer). The lower limit of the content of (D) stress relaxation material in the resin composition (layer) is not particularly limited, but from the viewpoint of further suppressing the occurrence of warping, is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, even more preferably 1% by mass or more, even more preferably 3% by mass or more, and particularly preferably 5% by mass or more, based on 100% by mass of the nonvolatile components in the resin composition (layer).

[0103] <(E) Hardener> The resin composition (layer) in the resin sheet of the present invention may contain a (E) curing agent as an optional component. The (E) curing agent may be used alone or in any combination of two or more. The (E) curing agent may have the function of reacting with the (A) epoxy resin to cure it. The (E) curing agent described here is a component other than the (D) stress relaxation material described above.

[0104] The (E) curing agent is not particularly limited, and examples thereof include active ester curing agents, phenol curing agents, carbodiimide curing agents, acid anhydride curing agents, amine curing agents, benzoxazine curing agents, cyanate ester curing agents, and thiol curing agents. In one embodiment, from the viewpoint of further reducing the dielectric loss tangent, the (E) curing agent preferably contains one or more curing agents selected from active ester curing agents and carbodiimide curing agents, and particularly preferably contains an active ester curing agent.

[0105] As the active ester curing agent, compounds having two or more highly reactive ester groups per molecule, such as phenol esters, thiophenol esters, N-hydroxyamine esters, and esters of heterocyclic hydroxy compounds, are generally preferred. The active ester compound is preferably one obtained by a condensation reaction between a carboxylic acid compound and / or a thiocarboxylic acid compound and a hydroxy compound and / or a thiol compound. From the viewpoint of improving heat resistance in particular, an active ester compound obtained from a carboxylic acid compound and a hydroxy compound is preferred, and an active ester compound obtained from a carboxylic acid compound and a phenol compound and / or a naphthol compound is more preferred. Examples of the carboxylic acid compound include benzoic acid, acetic acid, succinic acid, maleic acid, itaconic acid, phthalic acid, isophthalic acid, terephthalic acid, and pyromellitic acid. Examples of phenol compounds or naphthol compounds include hydroquinone, 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.

[0106] Specific examples of the active ester curing agent include dicyclopentadiene-type active ester compounds, naphthalene-type active ester compounds containing a naphthalene structure, active ester compounds containing an acetylated product of phenol novolac, and active ester compounds containing a benzoylated product of phenol novolac, and among these, at least one selected from dicyclopentadiene-type active ester compounds and naphthalene-type active ester compounds is more preferred. As the dicyclopentadiene-type active ester compound, an active ester compound containing a dicyclopentadiene-type diphenol structure is preferred.

[0107] Commercially available active ester curing agents include "EXB9451," "EXB9460," "EXB9460S," "HPC-8000L-65TM," "HPC-8000-65T," "HPC-8000H," and "HPC-8000H-65TM" (manufactured by DIC Corporation) as active ester compounds containing a dicyclopentadiene-type diphenol structure; and "HP-B-8151-62T," "EXB-8100L-65T," "EXB-9416-70BK," and "HPC-8150-62T" as active ester compounds containing a naphthalene structure. and "EXB-8" (manufactured by DIC Corporation); a phosphorus-containing active ester compound, "EXB9401" (manufactured by DIC Corporation); an active ester compound which is an acetylated product of phenol novolac, "DC808" (manufactured by Mitsubishi Chemical Corporation); active ester compounds which are benzoylated products of phenol novolac, "YLH1026," "YLH1030," and "YLH1048" (manufactured by Mitsubishi Chemical Corporation); an active ester compound containing a styryl group and a naphthalene structure, "PC1300-02-65MA" (manufactured by Air Water Inc.), and the like.

[0108] As the phenolic curing agent, a phenolic curing agent having a novolac structure is preferred from the viewpoint of heat resistance and water resistance. Also, from the viewpoint of adhesion to an adherend, a nitrogen-containing phenolic curing agent is preferred, and a triazine skeleton-containing phenolic curing agent is more preferred. Among them, a triazine skeleton-containing phenolic novolac resin is preferred from the viewpoint of highly satisfying heat resistance, water resistance, and adhesion. Specific examples of phenolic curing agents include "MEH-7700," "MEH-7810," and "MEH-7851" manufactured by Meiwa Chemical Industry Co., Ltd.; "NHN," "CBN," and "GPH" manufactured by Nippon Kayaku Co., Ltd.; "SN-170," "SN-180," "SN-190," "SN-475," "SN-485," "SN-495," "SN-375," and "SN-395" manufactured by Nippon Steel Chemical & Material Co., Ltd.; and "LA-7052," "LA-7054," "LA-3018," "LA-3018-50P," "LA-1356," "TD2090," and "KA-1160" manufactured by DIC Corporation.

[0109] Examples of carbodiimide curing agents include curing agents having one or more, preferably two or more, carbodiimide structures in one molecule, such as aliphatic biscarbodiimides such as tetramethylene-bis(t-butylcarbodiimide) and cyclohexane-bis(methylene-t-butylcarbodiimide); aromatic biscarbodiimides such as phenylene-bis(xylylcarbodiimide); and aliphatic polycarbodiimides such as polyhexamethylenecarbodiimide, polytrimethylhexamethylenecarbodiimide, polycyclohexylenecarbodiimide, poly(methylenebiscyclohexylenecarbodiimide), and poly(isophoronecarbodiimide). ; aromatic polycarbodiimides such as poly(phenylenecarbodiimide), poly(naphthylenecarbodiimide), poly(tolylenecarbodiimide), poly(methyldiisopropylphenylenecarbodiimide), poly(triethylphenylenecarbodiimide), poly(diethylphenylenecarbodiimide), poly(triisopropylphenylenecarbodiimide), poly(diisopropylphenylenecarbodiimide), poly(xylylenecarbodiimide), poly(tetramethylxylylenecarbodiimide), poly(methylenediphenylenecarbodiimide), and poly[methylenebis(methylphenylene)carbodiimide].

[0110] Commercially available carbodiimide curing agents include, for example, "Carbodilite V-02B," "Carbodilite V-03," "Carbodilite V-04K," "Carbodilite V-07," and "Carbodilite V-09" manufactured by Nisshinbo Chemical Inc.; and "Stavaxol P," "Stavaxol P400," and "Hykasil 510" manufactured by Rhein Chemie.

[0111] The acid anhydride curing agent may be a curing agent having one or more acid anhydride groups in one molecule, and a curing agent having two or more acid anhydride groups in one molecule is preferred. Specific examples of the acid anhydride curing agent 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 curing agents include "HNA-100," "MH-700," "MTA-15," "DDSA," and "OSA" manufactured by New Japan Chemical Co., Ltd.; "YH-306" and "YH-307" manufactured by Mitsubishi Chemical Corporation; "HN-2200" and "HN-5500" manufactured by Hitachi Chemical Co., Ltd.; and "EF-30," "EF-40," "EF-60," and "EF-80" manufactured by Clay Valley.

[0112] Examples of the amine curing agent include curing agents having one or more, preferably two or more, amino groups in one molecule, such as aliphatic amines, polyether amines, alicyclic amines, and aromatic amines, among which aromatic amines are preferred from the viewpoint of achieving the desired effects of the present invention. The amine curing agent is preferably a primary amine or a secondary amine, and more preferably a primary amine. Specific examples of amine-based curing agents include 4,4'-methylenebis(2,6-dimethylaniline), 4,4'-diaminodiphenylmethane, 4,4'-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)propane. propane, 3,3-dimethyl-5,5-diethyl-4,4-diphenylmethanediamine, 2,2-bis(4-aminophenyl)propane, 2,2-bis(4-(4-aminophenoxy)phenyl)propane, 1,3-bis(3-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, 1,4-bis(4-aminophenoxy)benzene, 4,4'-bis(4-aminophenoxy)biphenyl, bis(4-(4-aminophenoxy)phenyl)sulfone, bis(4-(3-aminophenoxy)phenyl)sulfone, and the like. Commercially available amine-based curing agents may be used, and examples thereof include "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., and "Epicure W" manufactured by Mitsubishi Chemical Corporation.

[0113] Specific examples of benzoxazine curing agents include "JBZ-OP100D" and "ODA-BOZ" manufactured by JFE Chemical Corporation; "HFB2006M" manufactured by Showa Polymer Co., Ltd.; and "Pd" and "Fa" manufactured by Shikoku Chemicals Corporation.

[0114] Examples of cyanate ester curing agents include bifunctional cyanate resins such as bisphenol A dicyanate, polyphenol cyanate (oligo(3-methylene-1,5-phenylene cyanate)), 4,4'-methylenebis(2,6-dimethylphenyl cyanate), 4,4'-ethylidene diphenyl dicyanate, hexafluorobisphenol A dicyanate, 2,2-bis(4-cyanate)phenylpropane, 1,1-bis(4-cyanatephenylmethane), bis(4-cyanate-3,5-dimethylphenyl)methane, 1,3-bis(4-cyanatephenyl-1-(methylethylidene))benzene, bis(4-cyanatephenyl)thioether, and bis(4-cyanatephenyl)ether; multifunctional cyanate resins derived from phenol novolac and cresol novolac; and prepolymers in which these cyanate resins are partially converted to triazine. Specific examples of cyanate ester curing agents include "PT30" and "PT60" (both phenol novolac type multifunctional cyanate ester resins) manufactured by Lonza Japan Co., Ltd., "BA230" and "BA230S75" (prepolymers in which part or all of bisphenol A dicyanate has been triazine converted to a trimer).

[0115] Examples of thiol-based curing agents include trimethylolpropane tris(3-mercaptopropionate), pentaerythritol tetrakis(3-mercaptobutyrate), and tris(3-mercaptopropyl)isocyanurate.

[0116] The reactive group equivalent of the (E) curing agent is preferably 50 g / eq. to 3000 g / eq., more preferably 100 g / eq. to 1000 g / eq., even more preferably 100 g / eq. to 500 g / eq., and particularly preferably 100 g / eq. to 300 g / eq. The reactive group equivalent is the mass of the (E) curing agent per equivalent of the reactive group.

[0117] The content of the (E) curing agent in the resin composition (layer) is not particularly limited, but is preferably 30% by mass or less, more preferably 20% by mass or less, even more preferably 10% by mass or less, and particularly preferably 5% by mass or less, based on 100% by mass of the nonvolatile components in the resin composition (layer). The lower limit of the content of the (E) curing agent in the resin composition (layer) is not particularly limited, but may be, for example, 0% by mass or more, 0.01% by mass or more, preferably 0.1% by mass or more, more preferably 1% by mass or more, and particularly preferably 3% by mass or more, based on 100% by mass of the nonvolatile components in the resin composition (layer).

[0118] <(F) Curing accelerator> The resin composition (layer) in the resin sheet of the present invention may contain, as an optional component, (F) a curing accelerator, which functions as a curing catalyst to accelerate the curing of (B) the epoxy resin.

[0119] Examples of the (F) curing accelerator include phosphorus-based curing accelerators, urea-based curing accelerators, guanidine-based curing accelerators, imidazole-based curing accelerators, metal-based curing accelerators, and amine-based curing accelerators. The (F) curing accelerator preferably contains a curing accelerator selected from imidazole-based curing accelerators and amine-based curing accelerators. The (F) curing accelerators may be used alone or in combination of two or more.

[0120] 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-butylmethylphosphonium tetraphenylborate; methyltriphenylphosphonium bromide, ethyltriphenylphosphonium bromide, propyltriphenylphosphonium bromide, butyltriphenylphosphonium bromide, benzyltriphenylphosphonium chloride, tetraphenylphosphonium bromide, p-tolyltriphenylphosphonium tetra-p-tolylborate, and tetraphenylphosphonium bromide. 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;

[0121] 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].

[0122] 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.

[0123] 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 , 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, 2-phenylimidazoline, and other imidazole compounds, as well as adducts of imidazole compounds with epoxy resins.

[0124] As the imidazole-based curing accelerator, commercially available products may be used, such as "1B2PZ", "2MZA-PW", "2PHZ-PW", and "C11Z-A" manufactured by Shikoku Chemical Industry Co., Ltd., and "P200-H50" manufactured by Mitsubishi Chemical Corporation.

[0125] 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.

[0126] Examples of the amine-based curing accelerator include trialkylamines such as triethylamine and tributylamine, 4-dimethylaminopyridine, benzyldimethylamine, 2,4,6-tris(dimethylaminomethyl)phenol, and 1,8-diazabicyclo(5,4,0)-undecene.

[0127] As the amine-based curing accelerator, commercially available products may be used, for example, "MY-25" manufactured by Ajinomoto Fine-Techno Co., Ltd.

[0128] The content of the (F) curing accelerator in the resin composition (layer) is not particularly limited, but is preferably 5% by mass or less, more preferably 1% by mass or less, even more preferably 0.5% by mass or less, and particularly preferably 0.1% by mass or less, based on 100% by mass of the nonvolatile components in the resin composition (layer). The lower limit of the content of the (F) curing accelerator in the resin composition (layer) is not particularly limited, but may be, for example, 0% by mass or more, 0.001% by mass or more, 0.01% by mass or more, or 0.05% by mass or more, based on 100% by mass of the nonvolatile components in the resin composition (layer).

[0129] <(G) Radical Polymerizable Compound> The resin composition (layer) in the resin sheet of the present invention may contain a (G) radically polymerizable compound as an optional component. The (G) radically polymerizable compound may be used alone or in any combination of two or more. The (G) radically polymerizable compound described here is a component other than the (A) epoxy resin, (D) stress relaxation material, and (E) curing agent described above.

[0130] In one embodiment, the (G) radical polymerizable compound is a radical polymerizable compound having an ethylenically unsaturated bond. The (G) radical polymerizable compound is not particularly limited, but may have a radical polymerizable group such as an unsaturated hydrocarbon group such as an allyl group, a 3-cyclohexenyl group, a 3-cyclopentenyl group, a 2-vinylphenyl group, a 3-vinylphenyl group, or a 4-vinylphenyl group; or an α,β-unsaturated carbonyl group such as an acryloyl group, a methacryloyl group, or a maleimide group (2,5-dihydro-2,5-dioxo-1H-pyrrol-1-yl group). In one embodiment, the (G) radical polymerizable compound preferably has a maleimide group. In one embodiment, the (G) radical polymerizable compound preferably has two or more radical polymerizable groups.

[0131] In the first embodiment, the radical polymerizable compound (G) is preferably represented by the formula (G-1):

[0132] [ka]

[0133] [In the formula, R 1 each independently represents an alkyl group; ring A and ring B each independently represent an aromatic ring which may have a substituent; and a represents an integer of 1 or greater. The maleimide compounds according to the first embodiment include maleimide compounds represented by the following formula: The a units may be the same or different for each unit. The maleimide compounds according to the first embodiment may be used singly or in combination of two or more types in any ratio.

[0134] In the present specification, the substituent is not particularly limited, and examples thereof include monovalent substituents such as an alkyl group, an alkenyl group, an aryl group, an aryl-alkyl group (an alkyl group substituted with an aryl group), an alkyl-aryl group (an aryl group substituted with an alkyl group), an alkyl-oxy group, an alkenyl-oxy group, an aryl-oxy group, an alkyl-carbonyl group, an alkenyl-carbonyl group, an aryl-carbonyl group, an alkyl-oxy-carbonyl group, an alkenyl-oxy-carbonyl group, an aryl-oxy-carbonyl group, an alkyl-carbonyl-oxy group, an alkenyl-carbonyl-oxy group, and an aryl-carbonyl-oxy group, and may also include divalent substituents such as an oxo group (═O) if substitutable.

[0135] The term "alkyl group" refers to a linear, branched, and / or cyclic monovalent aliphatic saturated hydrocarbon group. Unless otherwise specified, the alkyl group is preferably an alkyl group having 1 to 14 carbon atoms, more preferably an alkyl group having 1 to 10 carbon atoms, and even more preferably an alkyl group having 1 to 6 carbon atoms. Examples of the alkyl group include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, cyclopentyl, cyclohexyl, methylcyclohexyl, dimethylcyclohexyl, trimethylcyclohexyl, cyclopentylmethyl, and cyclohexylmethyl. The term "alkenyl group" refers to a linear, branched, and / or cyclic monovalent aliphatic unsaturated hydrocarbon group having at least one carbon-carbon double bond. Unless otherwise specified, the alkenyl (group) is preferably an alkenyl (group) having 2 to 14 carbon atoms, more preferably an alkenyl (group) having 2 to 10 carbon atoms, and even more preferably an alkenyl (group) having 2 to 6 carbon atoms. Examples of the alkenyl (group) include a vinyl group, a propenyl group, a butenyl group, a pentenyl group, a hexenyl group, a heptenyl group, an octenyl group, a nonenyl group, a decenyl group, and a cyclohexenyl group. The aryl (group) refers to a monovalent aromatic hydrocarbon group formed by removing one hydrogen atom from an aromatic carbon ring. Unless otherwise specified, the aryl (group) is preferably an aryl (group) having 6 to 14 carbon atoms, and particularly preferably an aryl (group) having 6 to 10 carbon atoms. Examples of the aryl (group) include a phenyl group, a 1-naphthyl group, and a 2-naphthyl group.

[0136] R 1each independently represent an alkyl group, and in one embodiment, preferably a methyl group. Ring A each independently represent an aromatic ring which may have a substituent, and in one embodiment, preferably a benzene ring which may have a substituent, more preferably a benzene ring which may have a substituent selected from alkyl groups, and even more preferably a benzene ring substituted with a group selected from alkyl groups. Ring B each independently represent an aromatic ring which may have a substituent, and in one embodiment, preferably a benzene ring which may have a substituent, more preferably a benzene ring which may have a group selected from alkyl groups, and even more preferably an (unsubstituted) benzene ring. a represents an integer of 1 or more, and preferably an integer of 1 to 20.

[0137] The radically polymerizable compound (G) in the first embodiment can be produced, for example, by using the method described in the Journal of Technical Disclosure No. 2020-500211 of the Japan Institute of Invention and Innovation, or a method equivalent thereto.

[0138] In the second embodiment, the radical polymerizable compound (G) is preferably represented by the formula (G-2′):

[0139] [ka]

[0140] [In the formula, ring C represents a monocycloalkane ring which may have a substituent, or a monocycloalkene ring which may have a substituent; b and c each independently represent an integer of 0 or 1 or greater, and the sum of b and c is 6 or greater; and * represents a bonding site.] The maleimide compound in the second embodiment may be used alone or in combination of two or more kinds in any ratio.

[0141] The monocycloalkane ring refers to a monocyclic aliphatic saturated hydrocarbon ring. The monocycloalkane ring is preferably a monocycloalkane ring having 4 to 14 carbon atoms, more preferably a monocycloalkane ring having 4 to 10 carbon atoms, and particularly preferably a monocycloalkane ring having 5 or 6 carbon atoms. Examples of the monocycloalkane ring include a cyclobutane ring, a cyclopentane ring, a cyclohexane ring, a cycloheptane ring, and a cyclooctane ring. The monocycloalkene ring refers to a monocyclic aliphatic unsaturated hydrocarbon ring having at least one carbon-carbon double bond. The monocycloalkene ring is preferably a monocycloalkene ring having 4 to 14 carbon atoms, more preferably a monocycloalkene ring having 4 to 10 carbon atoms, and particularly preferably a monocycloalkene ring having 5 or 6 carbon atoms. Examples of the monocycloalkene ring include a cyclobutene ring, a cyclopentene ring, a cyclohexene ring, a cycloheptene ring, a cyclooctene ring, a cyclopentadiene ring, and a cyclohexadiene ring.

[0142] Ring C represents a monocycloalkane ring which may have a substituent, or a monocycloalkene ring which may have a substituent. Ring C is preferably a monocycloalkane ring which may have a substituent selected from an alkyl group and an alkenyl group; or a monocycloalkene ring which may have a substituent selected from an alkyl group and an alkenyl group. Ring C is more preferably a monocycloalkane ring which may have a substituent selected from an alkyl group having 1 to 14 carbon atoms and an alkenyl group having 2 to 14 carbon atoms; or a monocycloalkene ring which may have a substituent selected from an alkyl group having 1 to 14 carbon atoms and an alkenyl group having 2 to 14 carbon atoms.

[0143] b and c each independently represent an integer of 0 or 1 or more, and the sum of b and c is 6 or more (preferably 8 or more, more preferably 10 or more). b and c are preferably each independently an integer of 0 to 20, and the sum of b and c is 6 or more (preferably 8 or more, more preferably 10 or more). b and c are more preferably each independently an integer of 1 to 20, and the sum of b and c is 6 or more (preferably 8 or more, more preferably 10 or more). b and c are further more preferably each independently an integer of 5 to 10. b and c are particularly preferably 8.

[0144] In the second embodiment, the radical polymerizable compound (G) is particularly preferably a compound represented by formula (G-2):

[0145] [ka]

[0146] [In the formula, R 2 each independently represents a substituent; each ring D independently represents an aromatic ring which may have a substituent; D 1 and D 2 are each independently a single bond, -C(R x )2-, -O-, -CO-, -S-, -SO-, -SO2-, -CONH-, -NHCO-, -COO-, or -OCO-; R x each independently represents a hydrogen atom or an alkyl group; each d independently represents 0 or 1; each e independently represents an integer of 0 or 1 or more; each f independently represents 0, 1, or 2; and each n independently represents an integer of 0 or 1 or more; and other symbols are as defined above. The e units, f units and n units may be the same or different from one another.

[0147] R 2Each independently represents a substituent, preferably an alkyl group. Each ring D independently represents an aromatic ring which may have a substituent, preferably a benzene ring which may be substituted with a group selected from alkyl groups. D 1 and D 2 are each independently a single bond, -C(R x )2-, -O-, -CO-, -S-, -SO-, -SO2-, -CONH-, -NHCO-, -COO-, or -OCO-, and preferably represents a single bond, -C(R x )2- or -O-. x are each independently a hydrogen atom or an alkyl group, preferably a hydrogen atom or a methyl group. d are each independently 0 or 1, preferably 0. e are each independently 0 or an integer of 1 or more, preferably 0, 1, 2 or 3, more preferably 0, 1 or 2. f are each independently 0, 1 or 2, preferably 0. n are 0 or an integer of 1 or more, preferably 0.

[0148] Formula (D) contained in formula (G-2):

[0149] [ka]

[0150] [In the formula, * indicates a binding site; other symbols are as defined above.] The partial structure represented by the formula (D-1) to (D-3):

[0151] [ka]

[0152] [In the formula, * is the same as above.] Examples of the partial structure include:

[0153] Commercially available products of the radically polymerizable compound (G) in the second embodiment include, for example, "BMI-689," "BMI-1500," "BMI-1700," and "BMI-3000J" manufactured by Designer Molecules, Inc.

[0154] The (G) radically polymerizable compound may contain either the preferred maleimide compound contained in the first embodiment or the preferred maleimide compound contained in the second embodiment, either alone, or in any combination of two or more kinds at any ratio.

[0155] The radical polymerizable group equivalent of the (G) radical polymerizable compound is preferably 250 g / eq. to 2500 g / eq., more preferably 300 g / eq. to 1500 g / eq. The radical polymerizable group equivalent of the (G) radical polymerizable compound represents the mass of the resin per equivalent of the radical polymerizable group.

[0156] The weight average molecular weight (Mw) of the radical polymerizable compound (G) is preferably 300 to 40,000, more preferably 300 to 10,000, and particularly preferably 300 to 7,000. The weight average molecular weight of the resin can be measured by gel permeation chromatography (GPC) as a polystyrene-equivalent value.

[0157] The content of the (G) radical polymerizable compound in the resin composition (layer) is not particularly limited, but is preferably 50% by mass or less, more preferably 40% by mass or less, even more preferably 30% by mass or less, even more preferably 20% by mass or less, and particularly preferably 10% by mass or less, based on 100% by mass of the nonvolatile components in the resin composition (layer). The lower limit of the content of the (G) radical polymerizable compound in the resin composition (layer) is not particularly limited, but is, for example, 0% by mass or more, preferably 0.01% by mass or more, more preferably 0.1% by mass or more, even more preferably 1% by mass or more, and particularly preferably 2% by mass or more, based on 100% by mass of the nonvolatile components in the resin composition (layer).

[0158] <(H)Thermoplastic resin> The resin composition (layer) in the resin sheet of the present invention may further contain a (H) thermoplastic resin as an optional component. The (H) thermoplastic resin described here is a component other than the (A) epoxy resin, (D) stress relaxation material, (E) curing agent, and (G) radical polymerizable compound described above.

[0159] Examples of (H) thermoplastic resins include polyimide resins, phenoxy resins, polyvinyl acetal resins, polyolefin resins, polybutadiene resins, polyamideimide resins, polyetherimide resins, polysulfone resins, polyethersulfone resins, polyphenylene ether resins, polycarbonate resins, polyetheretherketone resins, and polyester resins. In one embodiment, the (H) thermoplastic resin preferably contains a thermoplastic resin selected from the group consisting of polyimide resins and phenoxy resins, and more preferably contains a phenoxy resin. Furthermore, one type of thermoplastic resin may be used alone, or two or more types may be used in combination.

[0160] Specific examples of polyimide resins include "SLK-6100" manufactured by Shin-Etsu Chemical Co., Ltd., and "Rikacoat SN20" and "Rikacoat PN20" manufactured by New Japan Chemical Co., Ltd.

[0161] Examples of phenoxy resins include phenoxy resins having one or more skeletons selected from the group consisting of bisphenol A, bisphenol F, bisphenol S, bisphenolacetophenone, novolac, biphenyl, fluorene, dicyclopentadiene, norbornene, naphthalene, anthracene, adamantane, terpene, and trimethylcyclohexane. The terminal of the phenoxy resin may be any functional group such as a phenolic hydroxyl group or an epoxy group.

[0162] Specific examples of phenoxy resins include "1256" and "4250" manufactured by Mitsubishi Chemical Corporation (both of which are phenoxy resins containing a bisphenol A skeleton); "YX8100" manufactured by Mitsubishi Chemical Corporation (phenoxy resin containing a bisphenol S skeleton); "YX6954" manufactured by Mitsubishi Chemical Corporation (phenoxy resin containing a bisphenol acetophenone skeleton); "FX280" and "FX293" manufactured by Nippon Steel Chemical & Material Co., Ltd.; and "YX7200B35," "YL7500BH30," "YX6954BH30," "YX7553BH30," "YL7769BH30," "YL6794," "YL7213," "YL7290," and "YL7482" manufactured by Mitsubishi Chemical Corporation.

[0163] Examples of polyvinyl acetal resins include polyvinyl formal resins and polyvinyl butyral resins, with polyvinyl butyral resins being preferred. Specific examples of polyvinyl acetal resins include Denka Butyral 4000-2, Denka Butyral 5000-A, Denka Butyral 6000-C, and Denka Butyral 6000-EP, manufactured by Denki Kagaku Kogyo Co., Ltd.; and S-LEC BH series, BX series (e.g., BX-5Z), KS series (e.g., KS-1), BL series, and BM series, manufactured by Sekisui Chemical Co., Ltd.

[0164] Examples of polyolefin resins include ethylene copolymer resins such as low-density polyethylene, very low-density polyethylene, high-density polyethylene, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, and ethylene-methyl acrylate copolymer; and polyolefin polymers such as polypropylene and ethylene-propylene block copolymer.

[0165] 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.

[0166] Specific examples of polyamide-imide resins include "Vylomax HR11NN" and "Vylomax HR16NN" manufactured by Toyobo Co., Ltd. Specific examples of polyamide-imide resins also include modified polyamide-imides such as "KS9100" and "KS9300" (polysiloxane skeleton-containing polyamide-imides) manufactured by Hitachi Chemical Co., Ltd.

[0167] A specific example of the polyethersulfone resin is "PES5003P" manufactured by Sumitomo Chemical Co., Ltd.

[0168] Specific examples of polysulfone resins include polysulfones "P1700" and "P3500" manufactured by Solvay Advanced Polymers.

[0169] A specific example of the polyphenylene ether resin is NORYL SA90 manufactured by SABIC, etc. A specific example of the polyetherimide resin is ULTEM manufactured by GE, etc.

[0170] Examples of polycarbonate resins include hydroxyl group-containing carbonate resins, phenolic hydroxyl group-containing carbonate resins, carboxyl group-containing carbonate resins, acid anhydride group-containing carbonate resins, isocyanate group-containing carbonate resins, and urethane group-containing carbonate resins. Specific examples of polycarbonate resins include "FPC0220" manufactured by Mitsubishi Gas Chemical Company, Inc., "T6002" and "T6001" (polycarbonate diols) manufactured by Asahi Kasei Chemicals Corporation, and "C-1090," "C-2090," and "C-3090" (polycarbonate diols) manufactured by Kuraray Co., Ltd. Specific examples of polyether ether ketone resins include "Sumiploy K" manufactured by Sumitomo Chemical Co., Ltd.

[0171] Examples of polyester resins include polyethylene terephthalate resin, polyethylene naphthalate resin, polybutylene terephthalate resin, polybutylene naphthalate resin, polytrimethylene terephthalate resin, polytrimethylene naphthalate resin, and polycyclohexane dimethyl terephthalate resin.

[0172] From the viewpoint of significantly achieving the effects of the present invention, the weight average molecular weight (Mw) of the thermoplastic resin (H) is preferably 5,000 or more, more preferably 8,000 or more, even more preferably 10,000 or more, and particularly preferably 20,000 or more, and is preferably 100,000 or less, more preferably 70,000 or less, even more preferably 60,000 or less, and particularly preferably 50,000 or less.

[0173] The content of the (H) thermoplastic resin in the resin composition (layer) is not particularly limited, but from the viewpoint of significantly achieving the desired effects of the present invention, when the nonvolatile components in the resin composition (layer) are taken as 100% by mass, it is preferably 20% by mass or less, more preferably 10% by mass or less, even more preferably 5% by mass or less, even more preferably 3% by mass or less, and particularly preferably 2% by mass or less. The lower limit of the content of the (H) thermoplastic resin in the resin composition (layer) is not particularly limited, but when the nonvolatile components in the resin composition (layer) are taken as 100% by mass, it may be, for example, 0% by mass or more, 0.01% by mass or more, 0.1% by mass or more, 0.5% by mass or more, 1% by mass or more, etc.

[0174] <(I) Other additives> The resin composition of the present invention may further contain any additives. Examples of such additives include radical polymerization initiators such as peroxide radical polymerization initiators and azo radical polymerization initiators; thermosetting resins other than epoxy resins such as epoxy acrylate resins, urethane acrylate resins, urethane resins, cyanate resins, benzoxazine resins, unsaturated polyester resins, phenolic resins, melamine resins, and silicone resins; organometallic compounds such as organocopper compounds, organozinc compounds, and organocobalt compounds; colorants such as phthalocyanine blue, phthalocyanine green, iodine green, diazo yellow, crystal violet, titanium oxide, and carbon black; polymerization inhibitors such as hydroquinone, catechol, pyrogallol, and phenothiazine; leveling agents such as silicone leveling agents and acrylic polymer leveling agents; thickeners such as bentone and montmorillonite; antifoaming agents such as silicone antifoaming agents, acrylic antifoaming agents, fluorine-based antifoaming agents, and vinyl resin antifoaming agents; and benzotriazole. 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, red phosphorus), nitrogen-based flame retardants (e.g., melamine sulfate), halogen-based flame retardants, and inorganic flame retardants (e.g., antimony trioxide); dispersants such as phosphate ester-based dispersants, polyoxyalkylene-based dispersants, acetylene-based dispersants, silicone-based dispersants, anionic dispersants, and cationic dispersants; and stabilizers such as borate-based stabilizers, titanate-based stabilizers, aluminate-based stabilizers, zirconate-based stabilizers, isocyanate-based stabilizers, carboxylic acid-based stabilizers, and carboxylic acid anhydride-based stabilizers. The (I) other additives may be used singly or in combination of two or more in any ratio. The content of the (I) other additives can be appropriately determined by a person skilled in the art.

[0175] <Support> The resin sheet of the present invention has a support. Examples of the support in the resin sheet of the present invention include a film made of a plastic material, a metal foil, and a release paper, and a film made of a plastic material and a metal foil are preferred.

[0176] When a film made of a plastic material is used as the support, examples of the plastic material include polyesters such as polyethylene terephthalate (hereinafter sometimes abbreviated as "PET") and polyethylene naphthalate (hereinafter sometimes abbreviated as "PEN"), polycarbonate (hereinafter sometimes abbreviated as "PC"), acrylic polymers 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.

[0177] 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.).

[0178] The surface of the support that is to be bonded to the resin composition layer may be subjected to a matte treatment or a corona treatment.

[0179] The support may also be a support with a release layer, which has a release layer on the surface that bonds to 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 also 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.

[0180] The thickness of the support is not particularly limited, but is preferably in the range of 5 μm to 75 μm, more preferably 10 μm to 60 μm. When a support with a release layer is used, it is preferable that the thickness of the entire support with a release layer is in the above range.

[0181] <Protective film> The resin sheet of the present invention may further have a protective film similar to that of the support laminated 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. By laminating the protective film, it is possible to prevent adhesion of dust and the like to the surface of the resin composition (layer) and to prevent scratches. The resin sheet can be stored in a roll. When the resin sheet has a protective film, it can be used by peeling off the protective film.

[0182] <Method of manufacturing resin sheet> The resin sheet of the present invention can be produced, for example, by applying a varnish-like resin composition (resin varnish) onto a support using a die coater or the like, drying the applied composition, and forming a layer of the resin composition (layer) on the support.

[0183] The content of the (B) organic solvent in the varnish-like resin composition (resin varnish) is not particularly limited, but when the non-volatile components in the varnish-like resin composition are taken as 100% by mass, it is preferably 40% by mass or less, more preferably 35% by mass or less, and particularly preferably 30% by mass or less.

[0184] The content of aromatic solvents having a boiling point of less than 120°C in the (B) organic solvent contained in the varnish-like resin composition (resin varnish) may be preferably 0% by mass to 20% by mass, more preferably 0% by mass to 15% by mass, even more preferably 0% by mass to 10% by mass, and particularly preferably 0% by mass to 5% by mass, when the total (B) organic solvents contained in the varnish-like resin composition is taken as 100% by mass.

[0185] Drying can be carried out by methods such as heating or hot air blowing. The drying temperature conditions are not particularly limited, but are preferably set to 50°C to 150°C, more preferably 60°C to 130°C, and particularly preferably 70°C to 120°C. The drying time varies depending on the thickness of the resin composition (layer) and the components contained in the resin composition, but can be, for example, 1 minute to 10 minutes.

[0186] <Method for producing varnish-like resin composition (resin varnish)> A varnish-like resin composition (resin varnish) can be produced, for example, by adding (A) epoxy resin, (B) organic solvent, (C) inorganic filler, (D) stress relief material, optionally (E) curing agent, optionally (F) curing accelerator, optionally (G) radically polymerizable compound, optionally (H) thermoplastic resin, and optionally (I) other additives to an arbitrary preparation vessel in any order and / or simultaneously in part or in whole. Furthermore, during the process of adding and mixing each component, the temperature can be appropriately set, and heating and / or cooling may be performed temporarily or throughout the process. Furthermore, during or after the process of adding and mixing, the resin composition may be stirred or shaken using a stirring or shaking device such as a mixer to uniformly disperse the components. Furthermore, degassing may be performed under low-pressure conditions, such as under vacuum, simultaneously with stirring or shaking.

[0187] <Characteristics of resin sheets> The resin composition (layer) in the resin sheet of the present invention contains (A) an epoxy resin, (B) an organic solvent, (C) an inorganic filler, and (D) a stress relaxation material, and the content of aromatic solvents having a boiling point of less than 120°C in the (B) organic solvent is 0% to 9% by mass, assuming that the total (B) components is 100% by mass. By using such a resin sheet, it is possible to prevent unevenness after lamination and warpage after curing.

[0188] The resin sheet of the present invention can be characterized by being able to suppress the occurrence of unevenness after lamination. Thus, in one embodiment, after laminating the resin sheet of the present invention onto an inner layer substrate as in the following Test Example 4, when the resin composition (layer) around the inner layer substrate is observed for depressions, no depressions are observed.

[0189] The cured resin composition (layer) in the resin sheet of the present invention can be characterized by its ability to suppress warpage. Accordingly, in one embodiment, the amount of warpage measured as in Test Example 5 below can be preferably 2 mm or less.

[0190] In one embodiment, the resin sheet of the present invention can achieve good lamination properties because it can reduce the melt viscosity even while using (B) an inorganic filler. Therefore, in one embodiment, as shown in the following Test Example 3, the melt viscosity at 100°C of the resin composition (layer) in the resin sheet of the present invention can be preferably 50,000 poise or less, more preferably 30,000 poise or less, even more preferably 20,000 poise or less, even more preferably 15,000 poise or less, and particularly preferably 13,000 poise or less. The lower limit of the melt viscosity at 100°C of the resin composition (layer) can be, for example, 100 poise or more.

[0191] In one embodiment, the cured product of the resin composition (layer) in the resin sheet of the present invention may be characterized by a low dielectric loss tangent (Df). Thus, in one embodiment, the dielectric loss tangent (Df) of the cured product of the resin composition, as measured at 10 GHz and 23°C as in Test Example 6 below, may be preferably 0.0200 or less, 0.0150 or less, more preferably 0.00120 or less, 0.0100 or less, even more preferably 0.0095 or less, 0.0090 or less, and particularly preferably 0.0085 or less, 0.0080 or less.

[0192] In one embodiment, the resin composition (layer) in the resin sheet of the present invention is exposed to the outside air on the side of the resin sheet that is not in contact with the support (the other side is the laminated surface with the support), and after heat treatment at 190°C (under normal pressure) for 30 minutes as in Test Example 2 below, the weight loss rate of the resin composition layer after the resin sheet is heated is preferably 10% by mass or less, more preferably 9% by mass or less, even more preferably 8% by mass or less, and particularly preferably 7% by mass or less, from the viewpoint of further reducing the dielectric loss tangent (Df) and further suppressing the occurrence of warping, and the lower limit thereof is preferably 1% by mass or more, more preferably 1.4% by mass or more, even more preferably 1.6% by mass or more, and particularly preferably 1.8% by mass or more, from the viewpoint of achieving better lamination properties.

[0193] <Applications of resin sheets (resin compositions)> The resin sheet (resin composition) of the present invention can be suitably used as a resin sheet (resin composition) for insulation applications, particularly as a resin sheet (resin composition) for forming an insulating layer. Specifically, it can be suitably used as a resin sheet (resin composition) for forming an insulating layer (including a rewiring layer) to be formed on an insulating layer (resin sheet (resin composition) for forming an insulating layer for forming a conductor layer). It can also be suitably used as a resin sheet (resin composition) for forming an insulating layer of a printed wiring board (resin sheet (resin composition) for forming an insulating layer of a printed wiring board), as described below, and can be even more suitably used for forming an interlayer insulating layer of a printed wiring board (for an interlayer insulating layer of a printed wiring board). Furthermore, the resin sheet (resin composition) of the present invention provides an insulating layer with good component embedding properties, and can therefore be suitably used even when the printed wiring board is a circuit board with built-in components.

[0194] Furthermore, for example, when a semiconductor chip package is manufactured through the following steps (1) to (6), the resin sheet (resin composition) of the present invention can be suitably used as a resin sheet (resin composition) for a rewiring formation layer for forming a rewiring layer in the semiconductor chip package (a resin sheet (resin composition) for forming a rewiring formation layer), and as a resin sheet (resin composition) for encapsulating a semiconductor chip in the semiconductor chip package (a resin sheet (resin composition) for encapsulating a semiconductor chip). When a semiconductor chip package is manufactured, a rewiring layer may be further formed on the encapsulation layer. (1) a step of laminating a temporary fixing film on a substrate; (2) a step of temporarily fixing a semiconductor chip on a temporary fixing film; (3) forming an encapsulation layer on the semiconductor chip; (4) peeling the substrate and the temporary fixing film from the semiconductor chip; (5) forming a rewiring formation layer as an insulating layer on the surface of the semiconductor chip from which the base material and the temporary fixing film have been peeled off; and (6) A step of forming a rewiring layer as a conductor layer on the rewiring formation layer.

[0195] <Printed wiring board> The resin sheet of the present invention can be used to produce a printed wiring board, which includes an insulating layer obtained by curing the resin composition (layer) in the resin sheet of the present invention.

[0196] A printed wiring board can be produced, for example, by using the resin sheet of the present invention by a method including the following steps (I) and (II). (I) A step of laminating a resin sheet on an inner layer substrate so that the resin composition (layer) of the resin sheet is bonded to the inner layer substrate. (II) A step of curing (for example, heat curing) the resin composition (layer) to form an insulating layer.

[0197] The "inner layer substrate" used in step (I) is a member that will become the substrate of a printed wiring board, and examples thereof include glass epoxy substrates, metal substrates, polyester substrates, polyimide substrates, BT resin substrates, and thermosetting polyphenylene ether substrates. The substrate may have a conductor layer on one or both sides, and this conductor layer may be patterned. An inner layer substrate having a conductor layer (circuit) formed on one or both sides of the substrate may be referred to as an "inner layer circuit board." Furthermore, the "inner layer substrate" of the present invention also includes intermediate products on which an insulating layer and / or a conductor layer is to be further formed during the production of a printed wiring board. When the printed wiring board is a circuit board with built-in components, an inner layer substrate with built-in components may be used.

[0198] The inner layer substrate and the resin sheet can be laminated, 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 end plate) or a metal roll (SUS roll). Note that rather than pressing the thermocompression bonding member directly onto the resin sheet, it is preferable to press it via an elastic material such as heat-resistant rubber so that the resin sheet can sufficiently conform to the surface irregularities of the inner layer substrate.

[0199] 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 may be carried out under reduced pressure conditions, preferably at a pressure of 26.7hPa or less.

[0200] The lamination can be performed using a commercially available vacuum laminator, such as a vacuum pressure laminator manufactured by Meiki Seisakusho Co., Ltd., a vacuum applicator manufactured by Nikko Materials Co., Ltd., or a batch vacuum pressure laminator.

[0201] After lamination, the laminated resin sheets may be smoothed under normal pressure (atmospheric pressure), for example, by pressing a thermocompression member from the support side. The pressing conditions for the smoothing treatment may be the same as the thermocompression conditions for lamination. The smoothing treatment may be performed using a commercially available laminator. Note that lamination and smoothing treatment may be performed consecutively using the commercially available vacuum laminator.

[0202] The support may be removed between step (I) and step (II), or may be removed after step (II).

[0203] In step (II), the resin composition (layer) is cured (for example, thermally cured) to form an insulating layer. The curing conditions for the resin composition (layer) are not particularly limited, and conditions typically employed for forming insulating layers for printed wiring boards may be used.

[0204] For example, the thermal curing conditions for the resin composition (layer) vary depending on the types of components contained in the resin composition (layer), but in one embodiment, the curing temperature is preferably 120° C. to 240° C., more preferably 150° C. to 220° C., and even more preferably 170° C. to 210° C. The curing time is preferably 5 minutes to 120 minutes, more preferably 10 minutes to 100 minutes, and even more preferably 15 minutes to 100 minutes.

[0205] Before thermally curing the resin composition (layer), the resin composition (layer) may be preheated at a temperature lower than the curing temperature. For example, prior to thermally curing the resin composition (layer), the resin composition (layer) may be preheated at a temperature of 50°C to 120°C, preferably 60°C to 115°C, more preferably 70°C to 110°C for 5 minutes or more, preferably 5 minutes to 150 minutes, more preferably 15 minutes to 120 minutes, and even more preferably 15 minutes to 100 minutes.

[0206] When manufacturing a printed wiring board, the following steps may be further performed: (III) drilling holes in the insulating layer, (IV) roughening the insulating layer, and (V) forming a conductor layer. These steps (III) to (V) may be performed according to various methods known to those skilled in the art and used in manufacturing printed wiring boards. When the support is removed after step (II), the removal of the support may be performed between steps (II) and (III), between steps (III) and (IV), or between steps (IV) and (V). Furthermore, if necessary, the formation of the insulating layer and the conductor layer in steps (II) to (V) may be repeated to form a multilayer wiring board.

[0207] Step (III) is a step of drilling holes in the insulating layer, thereby forming holes such as via holes and through holes in the insulating layer. Step (III) may be performed using, for example, a drill, a laser, plasma, or the like, depending on the composition of the resin composition (layer) used to form the insulating layer. The dimensions and shape of the holes may be determined appropriately depending on the design of the printed wiring board.

[0208] Step (IV) is a step of roughening the insulating layer. Typically, smear removal is also performed in this step (IV). The roughening treatment procedure and conditions are not particularly limited, and known procedures and conditions commonly used in forming insulating layers for printed wiring boards can be adopted. For example, the insulating layer can be roughened by performing a swelling treatment with a swelling liquid, a roughening treatment with an oxidizing agent, and a neutralization treatment with a neutralizing liquid in this order.

[0209] The swelling liquid used in the roughening treatment is not particularly limited, but examples thereof include alkaline solutions and surfactant solutions, and is preferably an alkaline solution, with sodium hydroxide solution and potassium hydroxide solution being more preferred. Commercially available swelling liquids include "Swelling Dip Securigance P" and "Swelling Dip Securigance SBU" manufactured by Atotech Japan. The swelling treatment using a swelling liquid is not particularly limited, but can be carried out by, for example, 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.

[0210] The oxidizing agent used in the roughening treatment is not particularly limited, but examples thereof include alkaline permanganate solutions prepared by dissolving potassium permanganate or sodium permanganate in an aqueous solution of sodium hydroxide. Roughening treatment using an oxidizing agent such as 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.

[0211] The neutralizing solution used in the roughening treatment is preferably an acidic aqueous solution, and examples of commercially available products include "Reduction Solution Securigant P" manufactured by Atotech Japan.

[0212] Treatment with a neutralizing solution can be carried out by immersing the surface that has been roughened with an oxidizing agent in a neutralizing solution at 30° C. to 80° C. for 5 to 30 minutes. From the standpoint of workability, etc., a method in which the object that has been roughened with an oxidizing agent is immersed in a neutralizing solution at 40° C. to 70° C. for 5 to 20 minutes is preferred.

[0213] In one embodiment, the arithmetic mean roughness (Ra) of the insulating layer surface after the roughening treatment is not particularly limited, but is preferably 500 nm or less, more preferably 400 nm or less, and even more preferably 300 nm or less. The lower limit is not particularly limited, and may be, for example, 1 nm or more, 2 nm or more, etc. Furthermore, the root mean square roughness (Rq) of the insulating layer surface after the roughening treatment is preferably 500 nm or less, more preferably 400 nm or less, and even more preferably 300 nm or less. The lower limit is not particularly limited, and may be, for example, 1 nm or more, 2 nm or more, etc. The arithmetic mean roughness (Ra) and root mean square roughness (Rq) of the insulating layer surface can be measured using a non-contact surface roughness meter.

[0214] Step (V) is a step of forming a conductor layer, and the conductor layer is formed on the insulating layer. The conductor material used for the conductor layer is not particularly limited. In a preferred embodiment, the conductor layer contains one or more metals selected from the group consisting of gold, platinum, palladium, silver, copper, aluminum, cobalt, chromium, zinc, nickel, titanium, tungsten, iron, tin, and indium. The conductor layer may be a single metal layer or an alloy layer. Examples of alloy layers include layers formed from alloys of two or more metals selected from the above group (e.g., nickel-chromium alloys, copper-nickel alloys, and copper-titanium alloys). Among these, from the viewpoints of versatility in forming the conductor layer, cost, ease of patterning, etc., a single metal layer of chromium, nickel, titanium, aluminum, zinc, gold, palladium, silver, or copper, or an alloy layer of a nickel-chromium alloy, a copper-nickel alloy, or a copper-titanium alloy is preferred, a single metal layer of chromium, nickel, titanium, aluminum, zinc, gold, palladium, silver, or copper, or an alloy layer of a nickel-chromium alloy is more preferred, and a single metal layer of copper is even more preferred.

[0215] The conductor layer may have a single layer structure or a multi-layer structure in which two or more single metal layers or alloy layers made of different types of metals or alloys are laminated. When the conductor layer has a multi-layer structure, the layer in contact with the insulating layer is preferably a single metal layer of chromium, zinc, or titanium, or an alloy layer of a nickel-chromium alloy.

[0216] The thickness of the conductor layer depends on the desired design of the printed wiring board, but is generally 3 μm to 35 μm, preferably 5 μm to 30 μm.

[0217] In one embodiment, the conductor layer may be formed by plating. For example, a conductor layer having a desired wiring pattern can be formed by plating the surface of the insulating layer using a conventionally known technique such as a semi-additive method or a full-additive method. From the viewpoint of ease of production, it is preferable to form the conductor layer by a semi-additive method. An example of forming the conductor layer by a semi-additive method will be described below.

[0218] First, a plating seed layer is formed on the surface of an insulating layer by electroless plating. Next, a mask pattern is formed on the formed plating seed layer, exposing a portion of the plating seed layer corresponding to the desired wiring pattern. After a metal layer is formed on the exposed plating seed layer by electrolytic plating, the mask pattern is removed. Thereafter, unnecessary plating seed layer is removed by etching or the like, thereby forming a conductor layer having the desired wiring pattern.

[0219] In another embodiment, 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 resin composition layer and the metal foil may be laminated 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 conventionally known technique such as a subtractive method or a modified semi-additive method.

[0220] The metal foil can be produced by a known method such as an electrolytic method, a rolling method, etc. Examples of commercially available metal foils include HLP foil and JXUT-III foil manufactured by JX Nippon Mining & Metals Corporation, and 3EC-III foil and TP-III foil manufactured by Mitsui Mining & Smelting Co., Ltd.

[0221] <Semiconductor device> The printed wiring board described above can be used in a semiconductor device including a printed wiring board.

[0222] Examples of semiconductor devices include various semiconductor devices used in electrical appliances (for example, computers, mobile phones, digital cameras, and televisions) and vehicles (for example, motorcycles, automobiles, trains, ships, and aircraft). [Example]

[0223] The present invention will be described in more detail below with reference to examples. The present invention is not limited to these examples. In the following, "parts" and "%" representing amounts mean "parts by mass" and "% by mass", respectively, unless otherwise specified. Unless otherwise specified, the temperature and pressure conditions are room temperature (23°C) and normal pressure (1 atm), respectively.

[0224] <Synthesis Example 1: Synthesis of Elastomer A> 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.

[0225] 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. -1 The disappearance of the NCO peak was confirmed. The disappearance of the NCO peak was considered to be the end 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 an elastomer A having a polybutadiene structure and phenolic hydroxyl groups (phenolic hydroxyl group-containing polybutadiene resin: non-volatile components 50% by mass). The number-average molecular weight of elastomer A was 5900, and the glass transition temperature was -7°C.

[0226] <Synthesis Example 2: Synthesis of Elastomer B> A flask equipped with a stirrer, a thermometer, and a condenser was charged with 736 g of PGMEA as a solvent. 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 weight = 1000 g / eq., non-volatile components: 100%) were then charged and reacted at 70°C for 4 hours.

[0227] Next, 195.9 g (0.2 mol) of nonylphenol novolak resin (hydroxyl group equivalent weight = 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. -1 The disappearance of the NCO peak was confirmed. The disappearance of the NCO peak was considered to be the end of the reaction, and the reaction mixture was cooled to room temperature. The mixture was then filtered through a 100-mesh filter cloth to obtain Elastomer B (non-volatile components: 50% by mass) having a polycarbonate structure. Elastomer B had a number average molecular weight of 6,100 and a glass transition temperature of 5°C.

[0228] <Synthesis Example 3: Synthesis of maleimide compound A> A maleimide compound A (Mw / Mn = 1.81, a' = 1.47 (mainly 1, 2 or 3)) represented by the following formula (1) was prepared by the method described in Synthesis Example 1 of the Japan Institute of Invention and Innovation's Technical Journal Publication No. 2020-500211.

[0229] [ka]

[0230] Example 1 5 parts bisphenol A epoxy resin (Mitsubishi Chemical Corporation "828EL", epoxy equivalent 189 g / eq.), 1 part biphenyl epoxy resin (Nippon Kayaku Co., Ltd. "NC3000L", epoxy equivalent 271 g / eq.), 1 part carbodiimide curing agent (Nisshinbo Chemical Inc. "V-03", active group equivalent approx. 216, toluene solution with 50% solids by mass), 1 part cresol novolac resin (DIC Corporation "KA 3 parts of "-1160", phenolic hydroxyl group equivalent: 117 g / eq.), 20 parts of elastomer A (PGMEA solution with a solid content of 50% by mass), 4 parts of maleimide compound ("BMI-689" manufactured by Designer Molecules), spherical silica ("SO-C2" manufactured by Admatechs, average particle size 0.5 μm, specific surface area 5.8 m) surface-treated with an aminosilane coupling agent ("KBM573" manufactured by Shin-Etsu Chemical Co., Ltd.). 2 A varnish-like resin composition (resin varnish) was prepared by mixing 65 parts of hydroxybenzoates (1.05g / g), 0.05 parts of a curing accelerator (manufactured by Shikoku Chemicals Corporation, "1B2PZ", 1-benzyl-2-phenylimidazole), 10 parts of methyl ethyl ketone (MEK), and 5 parts of cyclohexanone (Anone), and dispersing the mixture uniformly in a high-speed rotating mixer.

[0231] Next, a PET film ("Lumirror R80" manufactured by Toray Industries, Inc.; thickness: 38 μm, softening point: 130°C; hereinafter sometimes referred to as "release PET") was prepared as a support. One main surface of the film had been treated with an alkyd resin-based release agent ("AL-5" manufactured by Lintec Corporation).

[0232] The resin composition (resin varnish) obtained above was uniformly applied to the release-treated surface of release PET using a die coater so that the thickness of the resin composition layer after drying would be 50 μm. The resin varnish was then dried at 80°C to 120°C (average 100°C). The drying time was adjusted by the method shown in Test Example 2 below so that the weight loss rate due to the heat treatment would be the value shown in Table 1 below. In this way, a resin sheet including a support and a resin composition layer provided on the support was produced.

[0233] <Example 2> A resin sheet was produced in the same manner as in Example 1, except that 1 part of a carbodiimide curing agent ("V-03" manufactured by Nisshinbo Chemical Inc., active group equivalent weight: approximately 216, toluene solution with a solid content of 50% by mass) was not used, the amount of cresol novolak resin ("KA-1160" manufactured by DIC Corporation, phenolic hydroxyl group equivalent weight: 117 g / eq.) used was changed from 3 parts to 3.5 parts, and 0.5 parts of toluene was further added.

[0234] Example 3 Spherical silica (Admatechs "SO-C2", average particle size 0.5 μm, specific surface area 5.8 m) surface-treated with an aminosilane coupling agent (Shin-Etsu Chemical Co., Ltd. "KBM573") 2 A resin sheet was produced in the same manner as in Example 1, except that the amount of the phenolic hydroxyl group equivalent (phenolic hydroxyl group equivalent: 117 g / eq.) used was changed from 65 parts to 60 parts, 1 part of the carbodiimide curing agent (Nisshinbo Chemical Inc.'s "V-03", active group equivalent: approximately 216, toluene solution with a solid content of 50 mass%) was not used, 4 parts of the maleimide compound (Designer Molecules' "BMI-689") was not used, the amount of the cresol novolak resin (DIC Corporation's "KA-1160", phenolic hydroxyl group equivalent: 117 g / eq.) used was changed from 3 parts to 3.5 parts, and 0.5 parts of toluene was further added.

[0235] Example 4 5 parts bisphenol A epoxy resin (Mitsubishi Chemical "828EL", epoxy equivalent 189 g / eq.), 1 part biphenyl epoxy resin (Nippon Kayaku "NC3000L", epoxy equivalent 271 g / eq.), 3 parts active ester curing agent (DIC "HPC-8000L-65T", active group equivalent approx. 223, MEK solution with 65% non-volatile components by mass), 3 parts triazine skeleton-containing cresol novolac curing agent (DIC The mixture consisted of 2 parts of propylene glycol monomethyl ether (PGM) solution (hydroxyl equivalent weight 151, non-volatile content 50%), 10 parts of elastomer A (PGMEA solution with solid content 50% by mass), 4 parts of maleimide compound A, and spherical silica (SO-C2 manufactured by Admatechs, average particle size 0.5 μm, specific surface area 5.8 m) surface-treated with an aminosilane coupling agent (KBM573 manufactured by Shin-Etsu Chemical Co., Ltd.). 260 parts of ethanol (1 / g), 0.05 parts of a curing accelerator ("4-dimethylaminopyridine" manufactured by Wako Pure Chemical Industries, Ltd.), 9.48 parts of methyl ethyl ketone (MEK), 0.53 parts of toluene, and 5 parts of cyclohexanone (Anone) were mixed and uniformly dispersed in a high-speed rotating mixer to prepare a varnish-like resin composition (resin varnish). Using the resin composition (resin varnish) thus obtained, a resin sheet was produced in the same manner as in Example 1.

[0236] <Example 5> A resin sheet was produced in the same manner as in Example 4, except that 3 parts of an active ester curing agent ("HPC-8000L-65™" manufactured by DIC Corporation, active group equivalent weight: approximately 223, non-volatile component: 65% by mass, toluene: MEK = 1:1 solution) was not used, the amount of a triazine skeleton-containing cresol novolac curing agent ("LA3018-50P" manufactured by DIC Corporation, hydroxyl group equivalent weight: 151, non-volatile component: 50% propylene glycol monomethyl ether (PGM) solution) used was changed from 2 parts to 5.9 parts, the amount of methyl ethyl ketone (MEK) used was changed from 9.48 parts to 10 parts, and 0.53 parts of toluene was not used.

[0237] Example 6 Spherical silica (Admatechs "SO-C2", average particle size 0.5 μm, specific surface area 5.8 m) surface-treated with an aminosilane coupling agent (Shin-Etsu Chemical Co., Ltd. "KBM573") 2 Instead of 65 parts of silica (65 parts per 1000g), spherical silica (Admatechs "SO-C4", average particle size 1.1 μm, specific surface area 4.5 m) was surface-treated with an aminosilane coupling agent (Shin-Etsu Chemical Co., Ltd. "KBM573") 2 A resin sheet was produced in the same manner as in Example 1, except that 50 parts of 1-benzyl-2-phenylimidazole (manufactured by Shikoku Chemical Industry Co., Ltd., "1B2PZ", 0.05 parts of a curing accelerator (manufactured by Wako Pure Chemical Industries, Ltd., "4-dimethylaminopyridine") was used in place of 0.05 parts of a curing accelerator (manufactured by Shikoku Chemical Industry Co., Ltd., "1B2PZ", 1-benzyl-2-phenylimidazole), 4 parts of maleimide compound A was used in place of 4 parts of maleimide compound (manufactured by Designer Molecules, "BMI-689"), and the amount of methyl ethyl ketone (MEK) used was changed from 10 parts to 15 parts.

[0238] Example 7 Bisphenol A epoxy resin (Mitsubishi Chemical Corporation "828EL", epoxy equivalent 189g / eq.) 3 parts, biphenyl epoxy resin (Nippon Kayaku Co., Ltd. "NC3000L", epoxy equivalent 271g / eq.) 1 part, naphthol aralkyl epoxy resin (Nippon Steel Chemical & Material Co., Ltd. "ESN475V", epoxy equivalent 332g / eq.) 2 parts, elastomer B (PGMEA solution with 50% solids by mass) 10 parts, Dow Chemical Japan "Paraloid EXL-2655" 5 parts, active ester curing agent The mixture consisted of 4.6 parts of a curing agent ("PC1300-02-65MA" manufactured by Air Water Inc., active group equivalent weight approximately 199, MAK solution with 65% non-volatile content by mass), 0.05 parts of a curing accelerator ("4-dimethylaminopyridine" manufactured by Wako Pure Chemical Industries, Ltd.), 3 parts of a thermoplastic resin ("YX7200B35" manufactured by Mitsubishi Chemical Corporation, Anone solution with 35% non-volatile content), and spherical silica ("SO-C2" manufactured by Admatechs Co., Ltd., average particle size 0.5 μm, specific surface area 5.8 m) surface-treated with an aminosilane coupling agent ("KBM573" manufactured by Shin-Etsu Chemical Co., Ltd.). 2 A varnish-like resin composition (resin varnish) was prepared by mixing 50 parts of cellulose acetate (cellulose acetate / g), 15 parts of methyl ethyl ketone (MEK), and 1 part of diethylene glycol monoethyl ether acetate (EDGAC) and dispersing the mixture uniformly in a high-speed rotating mixer. A resin sheet was produced using the resin composition (resin varnish) obtained in this manner in the same manner as in Example 1.

[0239] <Comparative Example 1> A resin sheet was produced in the same manner as in Example 1, except that 10 parts of toluene were used instead of 10 parts of methyl ethyl ketone (MEK).

[0240] <Comparative Example 2> Spherical silica (Admatechs "SO-C2", average particle size 0.5 μm, specific surface area 5.8 m) surface-treated with an aminosilane coupling agent (Shin-Etsu Chemical Co., Ltd. "KBM573") 2A resin sheet was produced in the same manner as in Example 1, except that the amount of Elastomer A (a PGMEA solution having a solid content of 50% by mass) used was changed from 65 parts to 40 parts, the amount of Elastomer B (a PGMEA solution having a solid content of 50% by mass) used was changed from 20 parts to 1 part, and 10 parts of toluene were used instead of 10 parts of methyl ethyl ketone (MEK).

[0241] <Comparative Example 3> A resin sheet was produced in the same manner as in Example 1, except that 5 parts of toluene were used instead of 10 parts of methyl ethyl ketone (MEK), and 5 parts of diethylene glycol monobutyl ether (DB) were further added.

[0242] <Comparative Example 4> Spherical silica (Admatechs "SO-C2", average particle size 0.5 μm, specific surface area 5.8 m) surface-treated with an aminosilane coupling agent (Shin-Etsu Chemical Co., Ltd. "KBM573") 2 A resin sheet was produced in the same manner as in Example 1, except that the amount of the curing agent ("V-03" manufactured by Nisshinbo Chemical Inc., active group equivalent weight: approximately 216, solid content: 50% by mass in toluene solution) used was changed from 1 part to 10 parts, and 10.5 parts of toluene were used instead of 10 parts of methyl ethyl ketone (MEK).

[0243] <Comparative Example 5> Spherical silica (Admatechs "SO-C2", average particle size 0.5 μm, specific surface area 5.8 m) surface-treated with an aminosilane coupling agent (Shin-Etsu Chemical Co., Ltd. "KBM573") 2 Instead of 65 parts of silica (65 parts per 1000g), spherical silica (Admatechs "SO-C4", average particle size 1.1 μm, specific surface area 4.5 m) was surface-treated with an aminosilane coupling agent (Shin-Etsu Chemical Co., Ltd. "KBM573") 2 A resin sheet was produced in the same manner as in Example 1, except that 20 parts of toluene (10 parts / g) was used instead of 10 parts of methyl ethyl ketone (MEK).

[0244] <Test Example 1: Analysis of organic solvents in resin composition layer of resin sheet by GC / MS (gas chromatography mass spectrometry)> A 5 mg portion of the resin composition layer was measured from the resin sheets prepared in the Examples and Comparative Examples, and the measured sample was processed in a GCMS-QP2020-NX (Shimadzu Corporation) at 250°C for 10 minutes in an oven, and measured under conditions of a sample line temperature of 260°C, a transfer line temperature of 260°C, and a cycle time of 55 minutes. The solvent type was identified from each detected peak, and the type and content of the organic solvent contained in the resin sheet of the supported resin sheet was analyzed by comparing it with a calibration curve prepared in advance.

[0245] <Test Example 2: Measurement of weight loss rate of resin composition layer of resin sheet due to heat treatment> The resin sheets prepared in the examples and comparative examples were cut into 10 cm x 10 cm pieces, placed in a desiccator together with thoroughly dried silica gel, and left for 30 minutes. The protective film was then peeled off and the mass (g) of the resin sheet was measured, and this value was designated α1 (g). Next, the resin sheet was heated in an oven at 190°C for 30 minutes, and after cooling in the desiccator together with silica gel for 30 minutes as before, the mass (g) of the resin sheet was measured again, and this value was designated α2 (g). The support alone was cut into 10 cm x 10 cm pieces and left in a desiccator for 30 minutes. The mass (g) of the support was then measured and designated β (g). The weight loss rate α (%) of the resin composition layer when the resin sheet was heat-treated at 190°C for 30 minutes was calculated using the following formula (A):

[0246]

number

[0247] <Test Example 3: Measurement and Evaluation of Melt Viscosity> The melt viscosity of the resin composition layer of the resin sheets produced in the examples and comparative examples was measured using a Rheosol-G3000 manufactured by UBM Corporation, with 1 g of resin and parallel plates with a diameter of 18 mm. The melt viscosity was measured starting at 60°C and rising to 200°C at a rate of 5°C / min, with a temperature interval of 2.5°C, and vibration at 1 Hz / deg. The results were evaluated according to the following criteria.

[0248] Evaluation criteria "Good": Melt viscosity at 100°C is 50,000 Poise or less "X": Melt viscosity at 100°C exceeds 50,000 Poise

[0249] <Test Example 4: Evaluation of unevenness after lamination> (1) Preparation of inner layer board Both sides of a glass cloth-based epoxy resin double-sided copper-clad laminate (copper foil thickness 18 μm, substrate thickness 0.4 mm, Panasonic "R1515A") with an inner layer circuit formed on it were etched 1 μm deep with a microetching agent (MEC "CZ8101") to roughen the copper surface.

[0250] (2) Laminating resin sheets The protective film was peeled off from the resin sheets prepared in the Examples and Comparative Examples to expose the resin composition layer. Using a batch-type vacuum pressure laminator (Nikko Materials Co., Ltd., two-stage build-up laminator "CVP700"), the resin composition layer was laminated onto both sides of the inner layer substrate so that it was in contact with the inner layer substrate. Lamination was performed by reducing the pressure to 13 hPa or less for 30 seconds, followed by pressure bonding at 120°C and a pressure of 0.74 MPa for 30 seconds. Next, a heat press was performed at 100°C and a pressure of 0.5 MPa for 60 seconds.

[0251] (3) Thermal curing of the resin composition layer The inner layer substrate laminated with the resin sheet was then placed in an oven at 130°C and heated for 30 minutes, and then transferred to an oven at 170°C and heated for 30 minutes to thermally cure the resin composition layer and form an insulating layer. The support was then peeled off to obtain a cured substrate having the insulating layer, inner layer substrate, and insulating layer in this order.

[0252] (4) Evaluation of unevenness on cured substrate The surface uniformity of the portions where the resin sheets were laminated (the surfaces opposite the laminated plate) on both sides of the cured substrate was visually observed and evaluated according to the following evaluation criteria.

[0253] Evaluation criteria "Good": No irregularities are observed and the surface is completely uniform, or irregularities are observed only within 1 cm of the outer periphery of the resin sheet laminated area, and the area inside is a completely uniform surface "X": When uneven areas are observed within 1 cm of the outer periphery of the resin sheet laminated area

[0254] <Test Example 5: Measurement and Evaluation of Warpage> The resin sheets prepared in the Examples and Comparative Examples were laminated onto one entire surface 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"), and the support was then peeled off. A second resin sheet was laminated onto the resin composition layer already laminated onto the 12-inch silicon wafer, resulting in a two-layer resin composition layer with a thickness of 100 μm. The resulting silicon wafer with the resin composition layer was heat-treated in an oven at 180°C for 90 minutes to form a silicon wafer with a cured resin composition layer (i.e., insulating layer). The amount of warpage of the silicon wafer with the insulating layer at 25°C was measured using a shadow moiré measurement device (Akorometrix, "Thermoire AXP"). Measurements were performed in accordance with JEITA EDX-7311-24, a standard of the Japan Electronics and Information Technology Industries Association. Specifically, a virtual plane calculated by the least squares method for all data on the substrate surface in the measurement area was used as the reference plane, and the difference between the minimum and maximum values ​​in the vertical direction from the reference plane was calculated as the amount of warpage, which was evaluated according to the following evaluation criteria.

[0255] Evaluation criteria "○": When the amount of warping is 2 mm or less "×": When the amount of warping is greater than 2 mm

[0256] <Test Example 6: Measurement and Evaluation of Dielectric Tangent> A portion of the resin sheet produced in each of the examples and comparative examples was cut out and heated at 180° C. for 90 minutes to thermally cure the resin composition layer. Thereafter, the support was peeled off to obtain a cured product for evaluation.

[0257] The cured product for evaluation was cut into a piece 2 mm wide and 80 mm long to obtain a test piece. The dielectric loss tangent (Df) of the obtained test piece was measured using an Agilent Technologies HP8362B by the cavity resonance perturbation method at a measurement frequency of 10 GHz and a measurement temperature of 23°C. Measurements were performed on two test pieces, and the average value was calculated. Evaluation was based on this average value according to the following evaluation criteria.

[0258] Evaluation criteria "Good": When the dielectric loss tangent (Df) is 0.008 or less "△": When the dielectric loss tangent (Df) is greater than 0.008 and less than 0.010 "×": When the dielectric loss tangent (Df) is 0.010 or more

[0259] The contents of non-volatile components and volatile components of the varnish-like resin compositions obtained in the Examples and Comparative Examples, as well as the measurement results and evaluation results of the Test Examples, are shown in Table 1 below.

[0260] [Table 1]

[0261] As shown in Table 1, by using a resin sheet having a resin composition layer containing (A) epoxy resin, (B) organic solvent, (C) inorganic filler, and (D) stress relaxation material, in which the content of aromatic solvents with a boiling point of less than 120°C in component (B) is 0% by mass to 9% by mass, assuming the total amount of component (B) to be 100% by mass, it is possible to suppress the occurrence of unevenness after lamination and warping after curing.

[0262] This application is based on patent application No. 2021-042917 (filing date: March 16, 2021) filed with the Japan Patent Office, the contents of which are incorporated in their entirety into this specification.

Claims

1. A resin sheet having a support and a resin composition layer provided on the support, the resin composition layer contains (A) an epoxy resin, (B) an organic solvent, (C) an inorganic filler, and (D) a stress relaxation material; The component (B) contains an organic solvent having a boiling point of 120°C or higher and lower than 220°C, the content of toluene in component (B) is 0% by mass to 9% by mass, where the total amount of component (B) is 100% by mass; the content of the organic solvent having a boiling point of less than 120°C in component (B) is 0% by mass to 30% by mass, relative to 100% by mass of the total amount of component (B); the content of the epoxy resin (A) in the resin composition layer is 8.6% by mass or less, based on 100% by mass of the nonvolatile components in the resin composition layer; A resin sheet, wherein the content of the component (C) in the resin composition layer is 73.4% by mass or more, when the total amount of nonvolatile components in the resin composition layer is 100% by mass.

2. A resin sheet having a support and a resin composition layer provided on the support, the resin composition layer contains (A) an epoxy resin, (B) an organic solvent, (C) an inorganic filler, and (D) a stress relaxation material; The component (B) contains an organic solvent having a boiling point of 120°C or higher and lower than 220°C, the content of toluene in component (B) is 0% by mass to 9% by mass, where the total amount of component (B) is 100% by mass; the content of organic solvents having a boiling point of 120°C or higher but lower than 220°C in component (B) is 85% by mass or higher, relative to 100% by mass of the total amount of component (B), the content of the epoxy resin (A) in the resin composition layer is 8.6% by mass or less, based on 100% by mass of the nonvolatile components in the resin composition layer; A resin sheet, wherein the content of the component (C) in the resin composition layer is 73.4% by mass or more, when the total amount of nonvolatile components in the resin composition layer is 100% by mass.

3. The resin sheet according to claim 1 or 2, wherein the content of the component (D) in the resin composition layer is 1% by mass or more, where the total amount of nonvolatile components in the resin composition layer is 100% by mass.

4. The resin sheet according to any one of claims 1 to 3, wherein the resin composition layer further contains (G) a radically polymerizable compound.

5. A resin sheet having a support and a resin composition layer provided on the support, the resin composition layer contains (A) an epoxy resin, (B) an organic solvent, (C) an inorganic filler, (D) a stress relaxation material, and (G) a radical polymerizable compound; The component (B) contains an organic solvent having a boiling point of 120°C or higher and lower than 220°C, the content of toluene in component (B) is 0% by mass to 9% by mass, where the total amount of component (B) is 100% by mass; the content of the organic solvent having a boiling point of less than 120°C in component (B) is 0% by mass to 30% by mass, relative to 100% by mass of the total amount of component (B); the content of the component (D) in the resin composition layer is 5% by mass to 15% by mass, relative to 100% by mass of the nonvolatile components in the resin composition layer; A resin sheet, wherein the content of the component (G) in the resin composition layer is 0.01% by mass to 10% by mass, where the total amount of nonvolatile components in the resin composition layer is 100% by mass.

6. A resin sheet having a support and a resin composition layer provided on the support, the resin composition layer contains (A) an epoxy resin, (B) an organic solvent, (C) an inorganic filler, (D) a stress relaxation material, and (G) a radical polymerizable compound; the content of toluene in component (B) is 0% by mass to 9% by mass, where the total amount of component (B) is 100% by mass; the content of organic solvents having a boiling point of 120°C or higher but lower than 220°C in component (B) is 85% by mass or higher, relative to 100% by mass of the total amount of component (B), the content of the component (D) in the resin composition layer is 5% by mass to 15% by mass, relative to 100% by mass of the nonvolatile components in the resin composition layer; A resin sheet, wherein the content of the component (G) in the resin composition layer is 0.01% by mass to 10% by mass, where the total amount of nonvolatile components in the resin composition layer is 100% by mass.

7. The resin sheet according to claim 5 or 6, wherein the content of the component (C) in the resin composition layer is 60% by mass or more, based on 100% by mass of nonvolatile components in the resin composition layer.

8. The resin sheet according to any one of claims 4 to 7, wherein the component (G) has a maleimide group.

9. The content (mass%) of the (C) component when the nonvolatile components in the resin composition layer are taken as 100 mass%, and the specific surface area (m ２ The resin sheet according to any one of claims 1 to 8, wherein the product of the value of (a) and (b) is 300 or more.

10. The content of the organic solvent having a boiling point of 220 ° C. or more in the component (B) is 0 mass% to 10 mass%, when the total amount of the component (B) is 100 mass%. The resin sheet according to any one of claims 1 to 9.

11. The content of the aromatic solvent in the (B) component is 0% by mass to 9% by mass, when the total of the (B) component is 100% by mass. The resin sheet according to any one of claims 1 to 10.

12. The resin sheet according to any one of claims 1 to 11, wherein the component (D) comprises a non-particulate stress relaxation material containing a resin having one or more structures selected from a polybutadiene structure and a polycarbonate structure.

13. The resin sheet according to any one of claims 1 to 12, wherein the component (D) comprises a particulate stress relaxation material.

14. The resin sheet according to claim 13, wherein the particulate stress relaxation material has an average particle size of 10,000 nm or less.

15. The resin sheet according to any one of claims 1 to 14, wherein the resin composition layer further contains (E) a curing agent.

16. The resin sheet according to claim 15, wherein the component (E) comprises one or more curing agents selected from an active ester curing agent and a carbodiimide curing agent.

17. The resin sheet according to claim 16 , wherein the component (E) includes an active ester-based curing agent.

18. The resin sheet according to any one of claims 1 to 17, wherein the resin composition layer further contains (F) a curing accelerator.

19. The resin composition layer has a weight loss rate of 1% by mass to 10% by mass after the surface not in contact with the support is exposed to the outside air and heated at 190 ° C. for 30 minutes. The resin sheet according to any one of claims 1 to 18.

20. The resin sheet according to any one of claims 1 to 19, wherein the dielectric loss tangent (Df) of the resin composition layer after curing is 0.0090 or less when measured at 10 GHz and 23 ° C.

21. The resin sheet according to any one of claims 1 to 20, wherein the melt viscosity of the resin composition layer at 100 ° C. is 50,000 poise or less.

22. A method for producing a printed wiring board, comprising the following steps (I) and (II): (I) A step of laminating the resin sheet according to any one of claims 1 to 21 so that the resin composition layer of the resin sheet is bonded to an inner layer substrate. (II) Step of curing the resin composition layer to form an insulating layer

23. (A) an epoxy resin, (B) an organic solvent, (C) an inorganic filler, and (D) a stress relaxation material; The component (B) contains an organic solvent having a boiling point of 120°C or higher and lower than 220°C, the content of toluene in component (B) is 0% by mass to 9% by mass, where the total amount of component (B) is 100% by mass; the content of the organic solvent having a boiling point of less than 120°C in component (B) is 0% by mass to 30% by mass, relative to 100% by mass of the total amount of component (B); the content of the epoxy resin (A) in the resin composition is 8.6% by mass or less, based on 100% by mass of the nonvolatile components in the resin composition; A resin composition, wherein the content of component (C) in the resin composition is 73.4% by mass or more, when the total amount of nonvolatile components in the resin composition is 100% by mass.

24. (A) an epoxy resin, (B) an organic solvent, (C) an inorganic filler, and (D) a stress relaxation material; The component (B) contains an organic solvent having a boiling point of 120°C or higher and lower than 220°C, the content of toluene in component (B) is 0% by mass to 9% by mass, where the total amount of component (B) is 100% by mass; the content of organic solvents having a boiling point of 120°C or higher but lower than 220°C in component (B) is 85% by mass or higher, relative to 100% by mass of the total amount of component (B), the content of the epoxy resin (A) in the resin composition is 8.6% by mass or less, based on 100% by mass of the nonvolatile components in the resin composition; A resin composition, wherein the content of component (C) in the resin composition is 73.4% by mass or more, when the total amount of nonvolatile components in the resin composition is 100% by mass.

25. (A) an epoxy resin, (B) an organic solvent, (C) an inorganic filler, (D) a stress relaxation material, and (G) a radical polymerizable compound; The component (B) contains an organic solvent having a boiling point of 120°C or higher and lower than 220°C, the content of toluene in component (B) is 0% by mass to 9% by mass, where the total amount of component (B) is 100% by mass; the content of the organic solvent having a boiling point of less than 120°C in component (B) is 0% by mass to 30% by mass, relative to 100% by mass of the total amount of component (B); The content of the component (D) in the resin composition is 5% by mass to 15% by mass, relative to 100% by mass of the nonvolatile components in the resin composition; A resin composition, wherein the content of the (G) component in the resin composition is 0.01% by mass to 10% by mass, where the total amount of nonvolatile components in the resin composition is 100% by mass.

26. (A) an epoxy resin, (B) an organic solvent, (C) an inorganic filler, (D) a stress relaxation material, and (G) a radical polymerizable compound; the content of toluene in component (B) is 0% by mass to 9% by mass, where the total amount of component (B) is 100% by mass; the content of organic solvents having a boiling point of 120°C or higher but lower than 220°C in component (B) is 85% by mass or higher, relative to 100% by mass of the total amount of component (B), The content of the component (D) in the resin composition is 5% by mass to 15% by mass, relative to 100% by mass of the nonvolatile components in the resin composition; A resin composition, wherein the content of the (G) component in the resin composition is 0.01% by mass to 10% by mass, where the total amount of nonvolatile components in the resin composition is 100% by mass.

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