Resin composition

Abstract

The present invention addresses the problem of providing a resin composition having excellent varnish stability. [Solution] A resin composition containing (A) an epoxy resin, (B) a maleimide resin, (C) an inorganic filler in an amount within a specific range, and (D) a specific cyclic phosphazene compound.

Description

TECHNICAL FIELD

[0001] The present application relates to a resin composition, a cured product thereof, a resin sheet, a circuit substrate, and a semiconductor device. BACKGROUND

[0002] Circuit substrates such as printed wiring boards are widely used in various electronic devices. As a manufacturing method of a circuit substrate, a manufacturing method based on a build-up method in which insulating layers and conductor layers are alternately overlaid on an inner layer substrate is known. The insulating layer is formed, for example, using a cured product of a resin composition containing a curable resin such as an epoxy resin. In order to improve flame retardancy, a resin composition containing a flame retardant is sometimes used (see Patent Documents 1 and 2).

[0003] PRIOR ART DOCUMENTS PATENT DOCUMENTS Patent Document 1: Japanese Patent Application Publication No. 2022-21767 Patent Document 2: Japanese Patent Application Publication No. 2021-04297 SUMMARY

[0004] PROBLEMS TO BE SOLVED BY THE INVENTION Generally, a resin composition is sometimes stored in a state of a resin varnish as a liquid composition containing a solvent. The term "varnish stability" means, unless otherwise specified, a property in which the precipitation of components in a resin varnish is small when the resin composition is stored in a state of the resin varnish.

[0005] Further, in the case where an insulating layer is formed using a cured product of a resin composition, it is required that the insulating layer maintains its insulating properties in a severe environment. Therefore, it is desirable that the cured product have high insulating reliability.

[0006] In addition, from the viewpoint of obtaining an insulating layer capable of reducing transmission loss, it is desirable that the cured product of the resin composition have a low dielectric loss tangent. From the viewpoint of obtaining the low dielectric loss tangent, a resin composition containing a large amount of inorganic filler material is sometimes used. However, in the past, an epoxy resin, an inorganic filler material, and a flame retardant were combined, and it was difficult to obtain a resin composition having excellent varnish stability and capable of obtaining a cured product having excellent insulating reliability and a low dielectric loss tangent.

[0007] The present application was invented in view of the above-described problems, and aims to provide a resin composition having excellent varnish stability and capable of obtaining a cured product having excellent insulating reliability and a low dielectric loss tangent, a resin sheet containing the resin composition, a cured product of the resin composition, a circuit substrate containing the cured product of the resin composition, and a semiconductor device containing the circuit substrate.

[0008] MEANS FOR SOLVING THE PROBLEMS The present inventors have conducted intensive studies in order to solve the above-described problems. As a result, the present inventors have found that a resin composition comprising (A) an epoxy resin, (B) a maleimide resin, (C) an inorganic filler material, and (D) a specific cyclic phosphazene compound in a specific amount is capable of solving the above-described problems, thereby completing the present application. That is, the present application comprises the following.

[0009] <1> A resin composition comprising (A) an epoxy resin, (B) a maleimide resin, (C) an inorganic filler material, and (D) a cyclic phosphazene compound represented by the following formula (1), wherein the amount of the (C) inorganic filler material is 60 mass% or more, relative to 100 mass% of non-volatile components of the resin composition, [Chemical Formula 1] (in formula (1), R 1 and R 2 (i) each independently represents a nitro group, an alkyl group or an alkoxy group having 1 to 8 carbon atoms optionally substituted by at least one selected from the group consisting of an alkyl group having 1 to 6 carbon atoms and an aryl group, and an aryl group or an aryloxy group having 6 to 20 carbon atoms optionally substituted by at least one selected from the group consisting of an alkyl group having 1 to 6 carbon atoms and an aryl group, any one of or (ii) forms, with each other, a saturated or unsaturated cyclic structure optionally substituted by an alkyl group having 1 to 6 carbon atoms or a carbonyl group; L represents a divalent heteroatom; a and b each independently represent an integer of 0 to 4; m each independently represents 0 or 1; n represents an integer of 3 to 8; the structures of the repeating units are each independent. <2> The resin composition according to <1>, wherein the amount ratio of the (B) maleimide resin to the (A) epoxy resin ((B) maleimide resin / (A) epoxy resin) is 0.01 or more and 2.0 or less, on a mass basis. <3> The resin composition according to <2>, wherein the amount ratio of the (B) maleimide resin to the (A) epoxy resin ((B) maleimide resin / (A) epoxy resin) is less than 0.6, on a mass basis. <4> The resin composition according to any one of <1> to <3>, wherein the amount of (A) the epoxy resin is 1 mass% or more and 30 mass% or less with respect to 100 mass% of nonvolatile components of the resin composition; <5> The resin composition according to any one of <1> to <4>, wherein the amount of (B) the maleimide resin is 0.1 mass% or more and 20 mass% or less with respect to 100 mass% of nonvolatile components of the resin composition; <6> The resin composition according to any one of <1> to <5>, wherein the amount of (C) the inorganic filler is 90 mass% or less with respect to 100 mass% of nonvolatile components of the resin composition; <7> The resin composition according to any one of <1> to <6>, wherein the amount of (D) the cyclic phosphazene compound is 0.1 mass% or more and 5 mass% or less with respect to 100 mass% of nonvolatile components of the resin composition; <8> The resin composition according to any one of <1> to <7>, wherein the amount of (D) the cyclic phosphazene compound is 0.01 mass% or more and 5 mass% or less with respect to 100 mass% of the inorganic filler; <9> The resin composition according to any one of <1> to <8>, wherein (D) the cyclic phosphazene compound is a particle having an average particle diameter of 1.5 μm or less; <10> The resin composition according to any one of <1> to <9>, wherein (D) the cyclic phosphazene compound is a particle having an average particle diameter of 0.8 μm or less; <11> The resin composition according to any one of <1> to <10>, wherein no cyclic phosphazene compound other than the (D) component is contained; <12> The resin composition according to any one of <1> to <11>, wherein the resin composition is not in a fibrous form; <13> The resin composition according to any one of <1> to <12>, wherein, (D) the cyclic phosphazene compound is a particle having an average particle diameter of D a μm, (C) the inorganic filler has an average particle diameter of D b μm, D a / D b is 0.1 or more and 10 or less; <14> The resin composition according to <13>, wherein D a / D b is 1.5 or less; <15> according to <1> ~ <14> The resin composition according to any one of the following methods, wherein (D) the cyclic phosphazene compound has a melting point of 260°C or higher; <16> according to <1> ~ <15> The resin composition according to any one of the following, wherein, in the case of a first dissolution test, the amount of (D) cyclic phosphazene compound dissolved is less than 0.04 g, wherein the first dissolution test is performed by ultrasonic treatment at 25°C for 10 minutes to dissolve the (D) cyclic phosphazene compound in 10 g of cyclohexanone; <17> according to <1> ~ <16> The resin composition according to any one of the following, wherein, in the case of a second dissolution test, the amount of (D) cyclic phosphazene compound dissolved is less than 0.3 g, wherein the second dissolution test is performed by ultrasonic treatment at 70°C for 10 minutes to dissolve the (D) cyclic phosphazene compound in 10 g of cyclohexanone; <18> according to <1> ~ <17> The resin composition according to any one of the following methods, wherein the resin composition comprises a ketone solvent; <19> according to <1> ~ <18> The resin composition described in any one of the following statements, wherein the resin composition comprises (J) a solvent, (J) Solvents include (J-1) non-aromatic high-boiling solvents that do not contain aromatic rings in their molecules and have a boiling point of over 100°C; <20> according to <19> The resin composition wherein, relative to 100% by mass of the total amount of solvent (J), the amount of non-aromatic high-boiling solvent (J-1) is 20% by mass or less; <21> according to <19> or <20> The resin composition wherein, relative to 100% by mass of the total amount of the resin composition, the amount of (J-1) non-aromatic high-boiling solvent is 4.8% by mass or less; <22> according to <1> ~ <21> The resin composition according to any one of the following, wherein (B) the maleimide resin comprises an aromatic maleimide resin; <23> A resin sheet comprising a support and a resin composition layer formed thereon. The resin composition layer contains <1> ~ <22> The resin composition described in any one of the following; <24> <1> ~ <22> The cured product of the resin composition described in any one of the above statements; <25> A circuit board comprising <1> ~ <22> The cured product of the resin composition described in any one of the above statements; <26> A semiconductor device comprising <25> The circuit board mentioned above.

[0010] Invention Effects According to the present invention, the following can be provided: a resin composition with excellent varnish stability and a cured resin composition that yields excellent insulation reliability and dielectric loss tangent; a resin sheet comprising the resin composition; a cured resin composition; a circuit board comprising the cured resin composition; and a semiconductor device comprising the circuit board. Detailed Implementation

[0011] The present invention will now be described with reference to embodiments and examples. However, the present invention is not limited to the embodiments and examples shown below, and may be implemented in any manner without departing from the scope of the claims and their equivalents.

[0012] In this specification, the term “optionally substituted” for a compound, group, or ring, unless otherwise stated, refers to both the case where the hydrogen atoms of the compound, group, or ring are not substituted by a substituent and the case where some or all of the hydrogen atoms of the compound, group, or ring are substituted by a substituent.

[0013] In this specification, the term "resin composition layer" means a layer containing a resin composition unless otherwise specified. Typically, a resin composition layer contains only a resin composition.

[0014] In this specification, unless otherwise specified, the term "cured layer" refers to a layer containing a cured resin composition. Typically, a cured layer contains only a cured resin composition.

[0015] <Summary of the Resin Composition> According to one embodiment of the present invention, the resin composition comprises (A) an epoxy resin, (B) a maleimide resin, a specific range of amounts of (C) an inorganic filler, and (D) a cyclic phosphazene compound represented by formula (1) below.

[0016] [Chemical Formula 2]

[0017] (In formula (1),) R 1 and R 2 , (i) Represented independently Nitro, An alkyl or alkoxy group having 1 to 8 carbon atoms, optionally substituted with at least one group selected from alkyl and aryl groups having 1 to 6 carbon atoms, and The aryl or aryloxy group having 6 to 20 carbon atoms is optionally substituted with at least one group selected from alkyl and aryl groups having 1 to 6 carbon atoms. any of them, or (ii) They form saturated or unsaturated cyclic structures with each other, which are optionally substituted with alkyl or carbonyl groups having 1 to 6 carbon atoms; L represents a divalent heteroatom; a and b each independently represent integers from 0 to 4; m independently represents 0 or 1; n represents an integer from 3 to 8; The structures of the repeating units are independent.

[0018] In the following description, the repeating unit shown in equation (2) below is sometimes referred to as the "phosphazene unit".

[0019] [Chemical Formula 3]

[0020] (The symbol R in equation (2)) 1 R 2 L, a, b, and m have the same meaning as the corresponding symbols in equation (1).

[0021] The resin composition according to this embodiment exhibits excellent varnish stability. Furthermore, according to the resin composition according to this embodiment, a cured product with excellent insulation reliability and dielectric loss tangent can be obtained. Moreover, the cured product of the resin composition according to this embodiment typically has a high glass transition temperature. Additionally, the cured product of the resin composition according to this embodiment typically has a small surface roughness after roughening treatment. Furthermore, the cured product of the resin composition according to this embodiment typically achieves high adhesion to the conductor layer.

[0022] <(A) Epoxy Resin> The resin composition according to this embodiment includes epoxy resin (A) as component (A). Epoxy resin (A) can be a curable resin having epoxy groups. The resin composition is cured by reacting epoxy resins (A) with each other. Alternatively, epoxy resin (A) can be cured by reacting with maleimide resin (B) in the presence of a catalyst such as an imidazole compound. Furthermore, epoxy resin (A) can be cured by reacting with any curing agent described later. One type of epoxy resin (A) can be used alone, or two or more types can be used in combination.

[0023] Examples of epoxy resins (A) include bisphenol A type epoxy resin, bisphenol C type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, bisphenol AF type epoxy resin, dicyclopentadiene type epoxy resin, triphenol type epoxy resin, naphthol phenolic varnish type epoxy resin, phenol phenolic varnish type epoxy resin, tert-butyl-catechol type epoxy resin, naphthalene type epoxy resin, naphthol type epoxy resin, anthracene type epoxy resin, glycidylamine type epoxy resin, glycidyl ester type epoxy resin, and cresol phenolic varnish type epoxy resin. Epoxy resins include phenolic aralkyl epoxy resins, biphenyl epoxy resins, linear aliphatic epoxy resins, butadiene-structured epoxy resins, alicyclic epoxy resins, heterocyclic epoxy resins, spirocyclic epoxy resins, cyclohexane-type epoxy resins, cyclohexanediol-type epoxy resins, naphthyl ether-type epoxy resins, trimethylolpropionic acid epoxy resins, tetraphenylethane-type epoxy resins, isocyanurate-type epoxy resins, and phenolphthalimidine-type epoxy resins. Biphenyl epoxy resins refer to epoxy resins with a biphenyl structure, where the biphenyl structure may optionally contain alkyl, alkoxy, or aryl substituents. Therefore, xylenol-type epoxy resins and biphenyl aralkyl epoxy resins can be included in the category of biphenyl epoxy resins.

[0024] From the viewpoint of obtaining a cured product with excellent heat resistance, (A) the epoxy resin preferably comprises an epoxy resin containing an aromatic structure. An aromatic structure is a chemical structure generally defined as aromatic, and also includes polycyclic aromatics and aromatic heterocycles. Examples of epoxy resins containing an aromatic structure include, for example, bisphenol A type epoxy resin, bisphenol C type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, bisphenol AF type epoxy resin, dicyclopentadiene type epoxy resin, triphenol type epoxy resin, naphthol phenolic varnish type epoxy resin, phenol phenolic varnish type epoxy resin, tert-butyl-catechol type epoxy resin, naphthol type epoxy resin, anthracene type epoxy resin, bixylenol type epoxy resin, glycidylamine type epoxy resin with an aromatic structure, and epoxy resins with aromatic structures. Glycidyl ester type epoxy resin, cresol phenolic varnish type epoxy resin, biphenyl type epoxy resin, linear aliphatic epoxy resin with aromatic structure, butadiene type epoxy resin with aromatic structure, alicyclic epoxy resin with aromatic structure, heterocyclic epoxy resin, spirocyclic epoxy resin with aromatic structure, cyclohexanediol type epoxy resin with aromatic structure, naphthyl ether type epoxy resin, trihydroxymethyl type epoxy resin with aromatic structure, tetraphenylethane type epoxy resin with aromatic structure, etc.

[0025] The preferred epoxy resins are bisphenol A type epoxy resin, bisphenol C type epoxy resin, bisphenol F type epoxy resin, dicyclopentadiene type epoxy resin, naphthalene type epoxy resin, biphenyl type epoxy resin, naphthalene ether type epoxy resin, phenol benzopyrrolidone type epoxy resin, and bixylenol type epoxy resin.

[0026] (A) The epoxy resin preferably comprises an epoxy resin having two or more epoxy groups in one molecule. The proportion of the epoxy resin having two or more epoxy groups in one molecule is preferably 50% by mass or more, more preferably 60% by mass or more, and even more preferably 70% by mass or more, relative to 100% by mass of the non-volatile component of (A) epoxy resin.

[0027] (A) Epoxy resins include epoxy resins that are liquid at 20°C (hereinafter sometimes referred to as "liquid epoxy resins") and epoxy resins that are solid at 20°C (hereinafter sometimes referred to as "solid epoxy resins"). (A) Epoxy resins may contain only liquid epoxy resins, or only solid epoxy resins, or a combination of liquid epoxy resins and solid epoxy resins.

[0028] As a liquid epoxy resin, a liquid epoxy resin having two or more epoxy groups in one molecule is preferred. Preferably, the liquid epoxy resin includes bisphenol A type epoxy resin, bisphenol C type epoxy resin, bisphenol F type epoxy resin, bisphenol AF type epoxy resin, naphthalene type epoxy resin, glycidyl ester type epoxy resin, glycidylamine type epoxy resin, phenolic varnish type epoxy resin, alicyclic epoxy resin with an ester skeleton, cyclohexane type epoxy resin, cyclohexanediethanol type epoxy resin, and epoxy resin with a butadiene structure; more preferably, bisphenol A type epoxy resin, bisphenol C type epoxy resin, bisphenol F type epoxy resin, and naphthalene type epoxy resin.

[0029] Specific examples of liquid epoxy resins include: DIC's "HP-4032", "HP-4032-D", and "HP-4032-SS" (naphthalene-type epoxy resin); and Mitsubishi Chemical's "828US", "828EL", "jER828", "jER828EL", "825", and "EPIKOTE". 828EL (Bisphenol A type epoxy resin); "jER807" and "1750" (Bisphenol F type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "jER152" (Phenolic varnish type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "630", "630LSD", and "604" (Glycidylamine type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "ED-523T" (Glycirol type epoxy resin) manufactured by ADEKA Corporation; "EP-3950L" and "EP-3980S" (Glycidylamine type epoxy resin) manufactured by ADEKA Corporation; "EP-4088S" (Dicyclopentadiene type epoxy resin) manufactured by ADEKA Corporation; "EP-506" (Polypropylene glycol type epoxy resin) manufactured by ADEKA Corporation; "ZX1059" (a mixture of bisphenol A type epoxy resin and bisphenol F type epoxy resin) manufactured by Nippon Steel Chemical Materials Co., Ltd.; Nagase ChemteX's "EX-721" (glycidyl ester type epoxy resin); Daicel's "CELLOXIDE2021P" (alicyclic epoxy resin with ester skeleton); Daicel's "PB-3600"; Nippon Soda's "JP-100" and "JP-200" (epoxy resin with butadiene structure); and Nippon Steel Chemical Materials' "ZX1658" and "ZX1658GS" (liquid 1,4-glycidylcyclohexane type epoxy resin), etc. Alternatively, the epoxy resin shown in formula (1) as described in Japanese Patent Application Publication No. 2024-85315 can be used.

[0030] As a 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. As a solid epoxy resin, preferred types include xylenol-type epoxy resin, naphthalene-type epoxy resin, naphthalene-type tetrafunctional epoxy resin, naphthol phenolic varnish-type epoxy resin, cresol phenolic varnish-type epoxy resin, dicyclopentadiene-type epoxy resin, triphenol-type epoxy resin, naphthol-type epoxy resin, biphenyl-type epoxy resin, naphthyl ether-type epoxy resin, anthracene-type epoxy resin, bisphenol A-type epoxy resin, bisphenol AF-type epoxy resin, phenol aralkyl-type epoxy resin, tetraphenylethane-type epoxy resin, and phenol benzopyrrolidone-type epoxy resin; more preferred types are biphenyl-type epoxy resin, naphthalene-type epoxy resin, naphthyl ether-type epoxy resin, xylenol-type epoxy resin, dicyclopentadiene-type epoxy resin, and phenol benzopyrrolidone-type epoxy resin.

[0031] Specific examples of solid epoxy resins include: DIC's "HP4032H" (naphthalene-type epoxy resin); DIC's "HP-4700" and "HP-4710" (naphthalene-type tetrafunctional epoxy resins); DIC's "N-690" (cresol phenolic varnish type epoxy resin); DIC's "N-695" (cresol phenolic varnish type epoxy resin); DIC's "HP-7200," "HP-7200HH," "HP-7200H," and "HP-7200L" (dicyclopentadiene type epoxy resin); and DIC's "EXA"... -7311", EXA-7311-G3", EXA-7311-G4", EXA-7311-G4S", HP-6000", HP-6000L (naphthalene ether type epoxy resin); EPPN-502H (triphenol type epoxy resin) manufactured by Nippon Chemical Co., Ltd.; NC7000L (naphthalene phenolic varnish type epoxy resin) manufactured by Nippon Chemical Co., Ltd.; NC3000H", NC3000", NC3000L", NC3000FH", NC3100 (biphenyl type epoxy resin) manufactured by Nippon Chemical Co., Ltd.; Nippon Steel Chemical Co., Ltd. Materials company's "ESN475V", "ESN4100V", "ESN-4100VEK75" (naphthalene-type epoxy resin); JITAC Chemical Materials Co., Ltd.'s "ESN485" (naphthol-type epoxy resin); JITAC Chemical Materials Co., Ltd.'s "ESN375" (dihydroxynaphthalene-type epoxy resin); Mitsubishi Chemical Corporation's "YX4000H", "YX4000", "YX4000HK", "YL7890" (bi-xylenol-type epoxy resin); Mitsubishi Chemical Corporation's "YL6121" (biphenyl-type epoxy resin); Mitsubishi Chemical Corporation's "YX8800" (… Anthracene-type epoxy resin; Mitsubishi Chemical's "YX7700" (phenol aralkyl type epoxy resin); Osaka Gas Chemical's "PG-100" and "CG-500"; Mitsubishi Chemical's "YX7760" (bisphenol AF type epoxy resin); Mitsubishi Chemical's "YL7800" (fluorene type epoxy resin); Mitsubishi Chemical's "jER1010" (bisphenol A type epoxy resin); Mitsubishi Chemical's "jER1031S" (tetraphenylethane type epoxy resin); Nippon Kayaku Co., Ltd.'s "WHR991S" (phenol benzopyrrolidone type epoxy resin), etc.

[0032] When the epoxy resin combination (A) comprises liquid epoxy resin and solid epoxy resin, their mass ratio (liquid epoxy resin: solid epoxy resin) is preferably 20:1 to 1:20, more preferably 10:1 to 1:10, and particularly preferably 7:1 to 1:7.

[0033] (A) The epoxy equivalent of the epoxy resin is preferably in the range of 50 g / eq. to 5000 g / eq., more preferably 60 g / eq. to 3000 g / eq., even more preferably 80 g / eq. to 2000 g / eq., and particularly preferably 110 g / eq. to 1000 g / eq. Epoxy equivalent represents the mass of resin per equivalent of epoxy groups. This epoxy equivalent can be determined according to JIS K 7236.

[0034] (A) The weight-average molecular weight (Mw) of the epoxy resin is preferably in the range of 100 to 5000, more preferably 250 to 3000, and even more preferably 400 to 1500. The weight-average molecular weight can be determined by gel permeation chromatography (GPC) as a value converted from polystyrene.

[0035] The amount of epoxy resin (A) relative to 100% by mass of the non-volatile components of the resin composition is preferably 1% by mass or more, more preferably 2% by mass or more, further preferably 5% by mass or more, preferably 30% by mass or less, more preferably 20% by mass or less, and further preferably 15% by mass or less. Unless otherwise specified, the non-volatile components of the resin composition refer to the components in the resin composition other than the solvent (J). When the amount of epoxy resin (A) is within the above range, the varnish stability of the resin composition and the insulation reliability and dielectric loss tangent of the cured product can be improved particularly effectively, and the glass transition temperature, surface roughness, and adhesion of the cured product are generally particularly good.

[0036] Relative to 100% by mass of the resin component in the resin composition, the amount of epoxy resin (A) is preferably 10% by mass or more, more preferably 20% by mass or more, further preferably 30% by mass or more, preferably 60% by mass or less, more preferably 50% by mass or less, and further preferably 40% by mass or less. Regarding the resin component of the resin composition, unless otherwise specified, it refers to the components other than (C) the inorganic filler material among the non-volatile components of the resin composition. When the amount of epoxy resin (A) is within the above range, the varnish stability of the resin composition and the insulation reliability and dielectric loss tangent of its cured product can be improved particularly effectively, and consequently, the glass transition temperature, surface roughness, and adhesion of the cured product are generally particularly good.

[0037] <(B) Maleimide Resin> The resin composition according to this embodiment includes (B) maleimide resin as component (B). (B) maleimide resin refers to a resin containing one or more, preferably two or more, maleimide groups (2,5-dihydro-2,5-dioxo-1H-pyrrole-1-yl) in one molecule. (B) maleimide resin can undergo free radical polymerization reactions between itself or with any free radical polymerizable resin. Furthermore, (B) maleimide resin can react with (A) epoxy resin in the presence of a catalyst such as an imidazole compound. Therefore, (B) maleimide resin can function as a curable resin that cures the resin composition through a reaction. (B) maleimide resin can be used alone or in combination of two or more.

[0038] Examples of (B) maleimide resins include: (B-1) aromatic maleimide resins having maleimide groups directly bonded to the aromatic ring, and (B-2) aliphatic maleimide resins having maleimide groups directly bonded to an aliphatic group. The maleimide resin may contain only (B-1) aromatic maleimide resin, only (B-2) aliphatic maleimide resin, or a combination of both (B-1) aromatic and (B-2) aliphatic maleimide resins. Preferably, the (B) maleimide resin contains (B-1) aromatic maleimide resin.

[0039] Furthermore, (B) the maleimide resin is preferably a resin containing a specific molecular backbone. Examples of preferred molecular backbones include, for instance, alicyclic backbones. Among alicyclic backbones, maleimide resins containing an indane backbone are particularly preferred.

[0040] As a preferred example of (B) maleimide resin, a maleimide resin comprising a partial structure shown in formula (B1) can be cited. Typically, the maleimide resin comprising the partial structure shown in formula (B1) is a (B-2) aliphatic maleimide resin. Furthermore, the maleimide resin comprising the partial structure shown in formula (B1) preferably has 2 or more maleimide groups per molecule, more preferably 2.

[0041] [Chemical Formula 4]

[0042] (In formula (B1), ring B) b Indicates an optional aliphatic hydrocarbon ring with substituents; i b and j b Each of them independently represents an integer greater than or equal to 0 or 1, and i b and j bThe total is 6 or more; * indicates a bonding site.

[0043] In equation (B1), ring B b This indicates an aliphatic hydrocarbon ring with optional substituents. The aliphatic hydrocarbon ring can be a saturated aliphatic hydrocarbon ring or an unsaturated aliphatic hydrocarbon ring. Furthermore, the aliphatic hydrocarbon ring can be a monocyclic aliphatic hydrocarbon ring having one ring or a polycyclic aliphatic hydrocarbon ring having multiple rings. The number of carbon atoms in the aliphatic hydrocarbon ring is preferably 4 or more, more preferably 5 or more, more preferably 14 or less, more preferably 10 or less, and even more preferably 6 or less.

[0044] Of the above, ring B b The aliphatic hydrocarbon ring is preferably a monocyclic aliphatic hydrocarbon ring, and more preferably a monocyclic saturated aliphatic hydrocarbon ring. Examples of monocyclic saturated aliphatic hydrocarbon rings include cyclobutane, cyclopentane, cyclohexane, cycloheptane, and cyclooctane rings, with cyclohexane ring being the most preferred.

[0045] As ring B b The substituents optionally present in the aliphatic hydrocarbon ring include, for example, halogen atoms, alkyl, alkenyl, aryl, aralkyl, alkyl-oxy, alkenyl-oxy, aryl-oxy, aralkyl-oxy, etc. Among these, alkyl and alkenyl are preferred, and alkyl is more preferred.

[0046] Examples of halogen atoms include fluorine, chlorine, bromine, and iodine.

[0047] The alkyl group can be a straight-chain, branched, or cyclic monovalent aliphatic saturated hydrocarbon group. The alkyl group preferably has 1 to 14 carbon atoms, more preferably 1 to 6, and even more preferably 1 to 3. Examples of alkyl groups include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, pentyl, isopentyl, sec-pentyl, neopentyl, tert-pentyl, hexyl, isohexyl, heptyl, isohexyl, octyl, isooctyl, tert-octyl, cyclopentyl, cyclohexyl, and cyclohexylmethyl.

[0048] The alkenyl group can be a straight-chain, branched, or cyclic monovalent aliphatic unsaturated hydrocarbon group having at least one carbon-carbon double bond. The alkenyl group preferably has 2 to 14 carbon atoms, more preferably 2 to 6, and even more preferably 2 or 3. Examples of alkenyl groups include vinyl, propenyl (allyl, 1-propenyl, isopropenyl), butenyl (1-butenyl, crotonyl, methylallyl, isocrotonyl, etc.), pentenyl (1-pentenyl, etc.), hexenyl (1-hexenyl, etc.), heptenyl (1-heptenyl, etc.), octenyl (1-octenyl, etc.), cyclopentenyl (2-cyclopentenyl, etc.), and cyclohexenyl (3-cyclohexenyl, etc.).

[0049] The aryl group can be a monovalent aromatic hydrocarbon group formed by removing one hydrogen atom from an aromatic hydrocarbon. The number of carbon atoms in the aryl group is preferably 6 to 14, more preferably 6 to 10. Examples of aryl groups include phenyl, 1-naphthyl, and 2-naphthyl.

[0050] The aralkyl group can be an alkyl group substituted with one or more (preferably one) aryl groups. The number of carbon atoms in the aralkyl group is preferably 7 to 15, more preferably 7 to 11. Examples of aralkyl groups include benzyl, phenethyl, hydrogenated cinnamyl, α-methylbenzyl, α-cumyl, 1-naphthylmethyl, 2-naphthylmethyl, etc.

[0051] In equation (B1), i b and j b Each can independently represent an integer greater than or equal to 0 or 1. Additionally, i b and j b The total is typically 6 or more, preferably 8 or more, and more preferably 10 or more. b and j b Preferably, it is an integer from 0 to 20, more preferably an integer from 1 to 20, and even more preferably an integer from 5 to 10. b and j b They can be the same or different. Where i b and j b The preferred value is 8.

[0052] As an example of a maleimide resin containing a partial structure as shown in formula (B1), a maleimide resin as shown in formula (B2) can be cited below.

[0053] [Chemical Formula 5]

[0054] (In formula (B2), R) b10 Each substituent is represented independently; cyclic C b Each independently represents an aromatic ring optionally having substituents; D b1 and D b2 Each independently represents 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; c b Each can independently represent 0 or 1; d b Each can independently represent an integer greater than or equal to 0 or 1; e b Each can independently represent 0, 1, or 2; n b Represents integers of 0 or higher; other symbols are as described above. Regarding c b unit, db Unit and n b Units, individually, each unit can be the same or different.

[0055] In equation (B2), R b10 Each substituent is represented independently. As R b10 Examples of substituents shown include halogen atoms, alkyl groups, alkenyl groups, aryl groups, aralkyl groups, alkyl-oxy groups, alkenyl-oxy groups, aryl-oxy groups, and aralkyl-oxy groups.

[0056] In equation (B2), ring C b Each of the terms independently represents an aromatic ring optionally having substituents. The aromatic ring is preferably an aromatic carbon ring. The aromatic ring is preferably a 5- to 14-membered aromatic ring, more preferably a 6- to 14-membered aromatic ring, and even more preferably a 6- to 10-membered aromatic ring. Examples of aromatic rings include benzene rings, naphthalene rings, anthracene rings, phenanthrene rings, etc., more preferably benzene rings or naphthalene rings, and even more preferably benzene rings.

[0057] As ring C b The aromatic ring may optionally contain substituents, such as halogen atoms, alkyl, alkenyl, aryl, aralkyl, alkyl-oxy, alkenyl-oxy, aryl-oxy, aralkyl-oxy, etc. Alkyl groups are preferred.

[0058] In equation (B2), D b1 and D b2 Each independently represents a single bond, -C(R) x -2-, -O-, -CO-, -S-, -SO-, -SO2-, -CONH-, -NHCO-, -COO- or -OCO-, preferably single bonds, -C(R x )2- or -O-, more preferably -O-. R x Each can be independently represented by a hydrogen atom or an alkyl group, preferably a hydrogen atom or a methyl group.

[0059] In equation (B2), c b Each can independently represent 0 or 1.

[0060] In equation (B2), d b Each of the integers can independently represent 0 or 1 or higher, preferably 0, 1, 2 or 3, more preferably 0, 1 or 2, and even more preferably 0 or 2.

[0061] In equation (B2), e b Each can be independently represented as 0, 1, or 2, preferably 0.

[0062] In equation (B2), n b Represents an integer of 0 or higher, preferably an integer from 0 to 10.

[0063] As an example of the partial structure shown in the following formula (B3) contained in formula (B2), the partial structures shown in formulas (b-1) to (b-3) described later can be cited.

[0064] [Chemical Formula 6]

[0065] [Chemical Formula 7]

[0066] (In the formula, * indicates the bonding site.)

[0067] Commercially available maleimide resins containing a portion of the structure shown in formula (B1) include, for example, “BMI-689”, “BMI-1500”, “BMI-1700”, “BMI-3000”, and “BMI-3000J” manufactured by Designer Molecules Inc.; and “SLK-1500” and “SLK-6895” manufactured by Shin-Etsu Chemical Co., Ltd.

[0068] As another preferred example of (B) maleimide resin, the maleimide resin shown in formula (B4) can be cited. This maleimide resin is generally classified as (B-1) aromatic maleimide resin.

[0069] [Chemical Formula 8]

[0070] (In formula (B4), ring E) b Ring F b and ring G b Each independently represents an aromatic ring optionally having substituents; Z b1 and Z b2 Each independently represents a single bond, -C(R) z -2-, -O-, -CO-, -S-, -SO-, -SO2-, -CONH-, or -NHCO-; R z Each can independently represent a hydrogen atom or an alkyl group; f b Represents an integer greater than or equal to 1; g b Each can independently represent 0 or 1; h b Each can independently represent 0, 1, 2, or 3. Regarding f... b Unit, g b Unit and h b Units, individually, each unit can be the same or different.

[0071] In equation (B4), ring E b Ring F b and ring G bEach independently represents an aromatic ring optionally having substituents. As ring E b Ring F b and ring G b Substituents in the ring can be categorized as halogen atoms, alkyl, alkenyl, aryl, aralkyl, alkyl-aryl-alkyl, alkyl-oxy, alkenyl-oxy, aryl-oxy, aralkyl-oxy, etc. (The text abruptly ends here, likely due to an incomplete sentence or missing information.) b Ring F b and ring G b Preferably, the benzene ring is optionally substituted, more preferably a benzene ring optionally substituted with a group selected from alkyl, aryl, and aralkyl groups. In one example, ring E b Ring F b and ring G b More preferably, it is an unsubstituted benzene ring. Alternatively, in another example, ring E... b Preferably, the benzene ring is substituted with alkyl groups such as methyl and ethyl, and the benzene ring is optionally substituted with alkyl-aryl-alkyl groups such as ethyl, phenyl, and ethyl; ring F b and ring G b More preferably, the benzene ring is optionally substituted with alkyl groups such as methyl and ethyl.

[0072] In equation (B4), Z b1 Each independently represents a single bond, -C(R) z -2-, -O-, -CO-, -S-, -SO-, -SO2-, -CONH-, or -NHCO-, preferably single bonds or -C(R) z )2-, more preferably a single bond. R z Each can be independently represented by a hydrogen atom or an alkyl group, preferably a hydrogen atom or a methyl group.

[0073] In equation (B4), Z b2 Each independently represents a single bond, -C(R) z -2-, -O-, -CO-, -S-, -SO-, -SO2-, -CONH- or -NHCO-, preferably -C(R z )2- or -O-. As mentioned above, R z Each can independently represent a hydrogen atom or an alkyl group. In Z b2 -C(R) z In the case of )2-, R z Preferably, it is a hydrogen atom or a methyl group. In one example, in Z... b2 -C(R) z In the case of )2-, by means of R z Both represent hydrogen atoms, and the Z b2 It can be -CH2-. In another example, in Z... b2 -C(R) z In the case of )2-, by means of R zBoth represent methyl, and the Z b2 It could be -C(CH3)2-. Furthermore, in another example, in Z... b2 -C(R) z In the case of )2-, by means of R z One of them represents a hydrogen atom, and the other represents a methyl group. This Z... b2 It can be -CH(CH3)-.

[0074] In equation (B4), f b It represents an integer greater than or equal to 1, preferably an integer from 1 to 100, and more preferably an integer from 1 to 10.

[0075] In equation (B4), g b Each can be independently represented as 0 or 1, preferably 1.

[0076] In equation (B4), h b Each can be independently represented as 0, 1, 2 or 3, preferably 0, 1 or 2, more preferably 0 or 1, and even more preferably 1.

[0077] Commercially available maleimide resins as shown in formula (B4) include, for example, "MIR-3000-70MT", "MIR-5000", and "MIR-5000-60T" manufactured by Nippon Kayaku Co., Ltd.; and "BMI-70" and "BMI-80" manufactured by KI Kasei Co., Ltd.

[0078] As a further preferred example of (B) maleimide resin, maleimide resins of formula (B5) can be cited. These maleimide resins are generally classified as (B-1) aromatic maleimide resins.

[0079] [Chemical Formula 9]

[0080] (In formula (B5), R) b30 Each independently represents an alkyl group; cyclic H b and Ring I b Each independently represents an aromatic ring optionally having substituents; m b Represents integers greater than or equal to 1. Regarding m... b Units, individually, each unit can be the same or different.

[0081] In equation (B5), R b30 Each can be independently represented as an alkyl group, preferably a methyl group.

[0082] In equation (B5), ring H b Each independently represents an aromatic ring optionally having substituents. As ring H bSubstituents in the ring can be categorized as halogen atoms, alkyl, alkenyl, aryl, aralkyl, alkyl-oxy, alkenyl-oxy, aryl-oxy, aralkyl-oxy, etc. b Preferably, the benzene ring has optional substituents, more preferably, the benzene ring is optionally alkyl-substituted, and even more preferably, the benzene ring is alkyl-substituted.

[0083] In equation (B5), ring I b Each independently represents an aromatic ring optionally having substituents. As ring I b Substituents in the ring can be categorized as halogen atoms, alkyl, alkenyl, aryl, aralkyl, alkyl-oxy, alkenyl-oxy, aryl-oxy, aralkyl-oxy, etc. b Preferably, the benzene ring has optional substituents, more preferably, it is a benzene ring optionally substituted with an alkyl group, and even more preferably, it is an unsubstituted benzene ring.

[0084] In equation (B5), m b It represents an integer greater than or equal to 1, preferably an integer from 1 to 20.

[0085] The maleimide resin shown in formula (B5) can be manufactured, for example, by the method described in or based on the Japanese Invention Association Publication No. 2020-500211.

[0086] As a further preferred example of (B) maleimide resin, examples include maleimide resins having a partial structure shown in formula (B6), a partial structure shown in formula (B7) chemically bonded to the partial structure shown in formula (B6), and a partial structure shown in formula (B8) chemically bonded to the partial structure shown in formula (B6). This maleimide resin is generally classified as (B-1) aromatic maleimide resin.

[0087] [Chemical Formula 10]

[0088] (In formula (B6), R) b40 Each independently represents an alkyl group having 1 to 18 carbon atoms, u b v represents an integer greater than 0 and less than 4. b This indicates the average number of repeating units. The two asterisks represent linking bonds, indicating that a linking bond exists in equation (B7) L. b41 or L b42 The position is chemically bonded, and another linking bond is in formula (B8) L. b43 or L b44 Chemical bonding occurs at the location of the bond.

[0089] [Chemical Formula 11]

[0090] (in formula (B7) or (B8),) R b41 and R b43 Each can independently represent a hydrocarbon group with 1 to 18 carbon atoms. R b42 and R b44 Each can independently represent a hydrogen atom or a hydrocarbon group with 1 to 18 carbon atoms. L b41 ~L b44 Each independently represents a connecting bond or a hydrogen atom, where, in L b41 or L b42 The position is chemically bonded to a portion of the structure shown in formula (B6), and in L b43 or L b44 The position of L is chemically bonded to the partial structure shown in formula (B6), and L is not chemically bonded to the partial structure shown in formula (B6). b43 ~L b42 (It is a hydrogen atom.)

[0091] In equation (B6), the two asterisks represent connecting keys. Of the two connecting keys, one is the L in equation (B7) above. b41 or L b42 Chemical bonding occurs at the position of [the bond]. Additionally, another linking bond is located at L in the above formula (B8). b43 or L b44 Chemical bonding occurs at the positions of the groups. Therefore, the benzene rings in formulas (B7) and (B8) are chemically bonded to a portion of the structure shown in formula (B6) at the para or ortho position relative to the maleimide group.

[0092] In equation (B6), R b40 Each group independently represents a hydrocarbon group having 1 to 18 carbon atoms. The hydrocarbon group preferably has 1 to 12 carbon atoms, more preferably 1 to 6. R b40 Preferably, it is an alkyl group, more preferably a straight-chain alkyl group, and particularly preferably a methyl group. R in formula (B) b40 The benzene ring that is bonded can be a benzene ring contained in the benzyl ether skeleton.

[0093] In equation (B6), u b R represents an integer greater than or equal to 0 and less than or equal to 4, preferably an integer less than or equal to 2, and particularly preferably 2. In formula (B6), R... b40 In the combined benzene ring, where the 1- and 3-positions are bonded by methylene groups, R is preferred. b40 Bonded at 4 and 6 bits.

[0094] In equation (B6), v bThe average number of repeating units is preferably 0 or more and 50 or less, preferably 0 or more and 30 or less, and preferably 0 or more and 15 or less. b It can be a number greater than 0, or it can be 1 or more.

[0095] In equation (B7), L b41 or L b42 Each can independently represent a bonding bond or a hydrogen atom. Specifically, in L... b41 or L b42 At at least one of the positions, the partial structure shown in formula (B6) is chemically bonded to the partial structure shown in formula (B7). Additionally, L... b41 or L b42 It is a hydrogen atom. It should be noted that L can also be... b41 and L b42 These two locations represent the partial structures shown in the chemical bonding formula (B6).

[0096] In equation (B7), R b41 Each group independently represents a hydrocarbon group having 1 to 18 carbon atoms. The hydrocarbon group preferably has 1 to 12 carbon atoms, more preferably 1 to 6. R b41 Preferably, it is a straight-chain alkyl group, and particularly preferably an ethyl group.

[0097] In equation (B7), R b42 Each group independently represents a hydrocarbon group having 1 to 18 hydrogen or carbon atoms. The hydrocarbon group preferably has 1 to 12 carbon atoms, more preferably 1 to 6. R b42 Preferably, it is a hydrogen atom or an alkyl group, more preferably a hydrogen atom or a straight-chain alkyl group.

[0098] In equation (B8), L b43 or L b44 Each can independently represent a bonding bond or a hydrogen atom. Specifically, in L... b43 or L b44 At least one of the positions, the partial structure shown in formula (B6) is chemically bonded to the partial structure shown in formula (B8). Additionally, L... b43 or L b44 It is a hydrogen atom. It should be noted that L can also be... b43 and L b44 These two locations represent the partial structures shown in the chemical bonding formula (B6).

[0099] In equation (B8), R b43 Each group independently represents a hydrocarbon group having 1 to 18 carbon atoms. The hydrocarbon group preferably has 1 to 12 carbon atoms, more preferably 1 to 6. As R b43 Preferably, it is a straight-chain alkyl group, and particularly preferably an ethyl group.

[0100] In equation (B8), R b44 Each group independently represents a hydrocarbon group having 1 to 18 hydrogen or carbon atoms. The hydrocarbon group preferably has 1 to 12 carbon atoms, more preferably 1 to 6. R b44 Preferably, it is a hydrogen atom or an alkyl group, more preferably a hydrogen atom or a straight-chain alkyl group.

[0101] The maleimide resin described above, containing the partial structures shown in formula (B6), formula (B7), and formula (B8), can be manufactured, for example, by the method described in Japanese Patent Application Publication No. 2024-4392 or a method based thereon.

[0102] (B) The maleimide equivalent of the maleimide resin is preferably 30 g / eq. or more, more preferably 75 g / eq. or more, even more preferably 150 g / eq. or more, even more preferably 200 g / eq. or more, even more preferably 250 g / eq. or more, even more preferably 300 g / eq. or more, preferably 2500 g / eq. or less, more preferably 2000 g / eq. or less, even more preferably 1500 g / eq. or less, even more preferably 1000 g / eq. or less, even more preferably 500 g / eq. or less. The maleimide equivalent indicates the mass of resin per 1 equivalent of maleimide groups.

[0103] (B) The weight average molecular weight of the maleimide resin is preferably 100 or more, more preferably 150 or more, even more preferably 200 or more, even more preferably 400 or more, even more preferably 500 or more, even more preferably 600 or more, preferably 10,000 or less, more preferably 7,000 or less, even more preferably 5,000 or less, even more preferably 3,000 or less.

[0104] The amount of (B-1) aromatic maleimide resin relative to 100% by mass of the non-volatile components of the resin composition is preferably 0.1% by mass or more, more preferably 1% by mass or more, further preferably 2% by mass or more, preferably 20% by mass or less, more preferably 10% by mass or less, further preferably 5% by mass or less, and particularly preferably 3.5% by mass or less. When the amount of (B-1) aromatic maleimide resin is within the above range, it can particularly effectively improve the varnish stability of the resin composition and the insulation reliability and dielectric loss tangent of the cured product, thereby generally enabling the cured product to have particularly good glass transition temperature, surface roughness, and adhesion.

[0105] The amount of (B-1) aromatic maleimide resin relative to 100% by mass of the resin component in the resin composition is preferably 0.1% by mass or more, more preferably 1% by mass or more, further preferably 5% by mass or more, preferably 40% by mass or less, more preferably 30% by mass or less, further preferably 20% by mass or less, and particularly preferably 11% by mass or less. When the amount of (B-1) aromatic maleimide resin is within the above range, it is particularly effective in improving the varnish stability of the resin composition and the insulation reliability and dielectric loss tangent of the cured product, thereby generally resulting in particularly good glass transition temperature, surface roughness, and adhesion of the cured product.

[0106] The amount of (B-2) aliphatic maleimide resin relative to 100% by mass of the non-volatile components of the resin composition is preferably 0.1% by mass or more, more preferably 1% by mass or more, further preferably 2% by mass or more, preferably 20% by mass or less, more preferably 10% by mass or less, further preferably 5% by mass or less, and particularly preferably 3.5% by mass or less. When the amount of (B-2) aliphatic maleimide resin is within the above range, it can particularly effectively improve the varnish stability of the resin composition and the insulation reliability and dielectric loss tangent of the cured product, thereby generally enabling the cured product to have particularly good glass transition temperature, surface roughness, and adhesion.

[0107] The amount of (B-2) aliphatic maleimide resin relative to 100% by mass of the resin component in the resin composition is preferably 0.1% by mass or more, more preferably 1% by mass or more, further preferably 5% by mass or more, preferably 40% by mass or less, more preferably 30% by mass or less, further preferably 20% by mass or less, and particularly preferably 11% by mass or less. When the amount of (B-2) aliphatic maleimide resin is within the above range, the varnish stability of the resin composition and the insulation reliability and dielectric loss tangent of the cured product can be improved particularly effectively, and the glass transition temperature, surface roughness and adhesion of the cured product are generally particularly good.

[0108] The mass ratio of (B-2) aliphatic maleimide resin to (B-1) aromatic maleimide resin ((B-2) / (B-1)) can be 0.0 or greater than 0.0. The mass ratio ((B-2) / (B-1)) is preferably 0.1 or more, more preferably 0.2 or more, even more preferably 0.5 or more, preferably 1000 or less, more preferably 100 or less, and even more preferably 10 or less.

[0109] Relative to 100% by mass of the non-volatile components of the resin composition, the amount of (B) maleimide resin is preferably 0.1% by mass or more, more preferably 1% by mass or more, further preferably 2% by mass or more, preferably 20% by mass or less, more preferably 10% by mass or less, and further preferably 6% by mass or less. When the amount of (B) maleimide resin is within the above range, it is particularly effective to improve the varnish stability of the resin composition and the insulation reliability and dielectric loss tangent of the cured product, thereby generally enabling the cured product to have particularly good glass transition temperature, surface roughness, and adhesion.

[0110] Relative to 100% by mass of the resin component in the resin composition, the amount of (B) maleimide resin is preferably 0.1% by mass or more, more preferably 1% by mass or more, further preferably 5% by mass or more, particularly preferably 8% by mass or more, preferably 40% by mass or less, more preferably 30% by mass or less, and further preferably 20% by mass or less. When the amount of maleimide resin is within the above range, it is particularly effective in improving the varnish stability of the resin composition and the insulation reliability and dielectric loss tangent of the cured product, thereby generally resulting in particularly good glass transition temperature, surface roughness, and adhesion of the cured product.

[0111] Based on mass, the ratio of (B) maleimide resin to (A) epoxy resin ((B) maleimide resin / (A) epoxy resin) is preferably 0.01 or more, more preferably 0.10 or more, further preferably 0.20 or more, particularly preferably 0.23 or more, preferably 2.0 or less, more preferably 1.0 or less, further preferably less than 0.6, and even more preferably less than 0.5. When the ratio ((B) maleimide resin / (A) epoxy resin) is within the above range, the varnish stability of the resin composition and the insulation reliability and dielectric loss tangent of the cured product can be improved particularly effectively, thereby generally resulting in particularly good glass transition temperature, surface roughness, and adhesion of the cured product.

[0112] <(C) Inorganic filler materials> The resin composition according to this embodiment includes (C) inorganic filler material as component (C). (C) inorganic filler material is particles of inorganic material. Therefore, (C) inorganic filler material is contained in the resin composition in the form of particles, and is usually contained in the cured product in a form that maintains the particle state.

[0113] Inorganic compounds are typically used as inorganic materials to form the inorganic filler material (C). Examples of materials that can be used as the inorganic filler material (C) include, for example, silica, alumina, glass, cordierite, silicon oxide, barium sulfate, barium carbonate, talc, clay, mica powder, zinc oxide, hydrotalcite, boehmite, aluminum hydroxide, magnesium hydroxide, calcium carbonate, magnesium carbonate, magnesium oxide, boron nitride, aluminum nitride, manganese nitride, aluminum borate, strontium carbonate, strontium titanate, calcium titanate, magnesium titanate, bismuth titanate, titanium oxide, zirconium oxide, barium titanate, barium zirconate titanate, barium zirconate, calcium zirconate, zirconium phosphate, and zirconium tungstate phosphate. Among these, silica and alumina are preferred, and silica is particularly preferred. Therefore, the inorganic filler material (C) preferably contains silica, but may also contain only silica. Examples of silica include, for example, amorphous silica, fused silica, crystalline silica, synthetic silica, and hollow silica. Furthermore, spherical silica is preferred as the silica. (C) One type of inorganic filler material may be used alone, or two or more types may be used in combination.

[0114] (C) Inorganic filler materials can be classified into hollow inorganic filler materials with internal pores and solid inorganic filler materials without internal pores. (C) Inorganic filler materials may contain only hollow inorganic filler materials, or only solid inorganic filler materials, or a combination of hollow inorganic filler materials and solid inorganic filler materials.

[0115] Hollow inorganic filler materials with internal pores typically have a porosity greater than 0% by volume due to the presence of pores. (C) When the inorganic filler material includes hollow inorganic filler material, the relative permittivity of the cured material can be reduced. The porosity range of the hollow inorganic filler material is preferably 5% by volume or more, more preferably 10% by volume or more, further preferably 20% by volume or more, preferably 95% by volume or less, more preferably 90% by volume or less, and further preferably 85% by volume or less. The porosity P (volume%) of the particles is defined as the volume ratio of the total volume of one or more pores present inside the particles to the overall volume of the particles relative to the outer surface of the particles (total volume of pores / volume of particles). This porosity P can be measured using the actual density (apparent density) D of the particles. M (g / cm 3 The theoretical value (true density) of the material density of the particles and the density of the particles. T (g / cm 3 ), which is calculated using the following formula (M1).

[0116] [Mathematical Expression 1]

[0117] The amount of hollow inorganic filler material relative to the total amount of (C) inorganic filler material is 100% by mass, which can be 0% by mass or greater than 0% by mass, preferably 1% by mass or more, more preferably 2% by mass or more, even more preferably 3% by mass or more, preferably 80% by mass or less, more preferably 60% by mass or less, even more preferably 40% by mass or less.

[0118] Commercially available products as (C) inorganic filler materials include: "SP60-05" and "SP507-05" manufactured by Nippon Steel Chemicals and Materials Co., Ltd.; "YC100C", "YA050C", "YA050C-MJE", "YA010C", "SC2500SQ", "SO-C4", "SO-C2", and "SO-C1" manufactured by Yatoma Co., Ltd.; "UFP-30", "DAW-03", and "FB-105FD" manufactured by Denka Co., Ltd.; "Silfil NSS-3N", "Silfil NSS-4N", and "Silfil NSS-5N" manufactured by Tokuyama Co., Ltd.; "CellSpheres" and "MGH-005" manufactured by Pacific Cement Co., Ltd.; and "LHP-208" manufactured by Ube EXSYMO Co., Ltd., etc.

[0119] (C) The average particle size of the inorganic filler material is preferably 0.01 μm or more, more preferably 0.05 μm or more, even more preferably 0.1 μm or more, preferably 10 μm or less, more preferably 5 μm or less, even more preferably 3 μm or less, and even more preferably 2 μm or less.

[0120] (C) The average particle size of inorganic filler materials can be measured using laser diffraction / scattering methods based on the Mie scattering theory. Specifically, a laser diffraction-scattering particle size distribution measuring device can be used to prepare the particle size distribution of the inorganic filler material on a volume basis, and the median particle size can be used as the average particle size for measurement. The sample for measurement can be prepared by weighing 100 mg of inorganic filler material and 10 g of methyl ethyl ketone into a vial and dispersing it ultrasonically for 10 minutes. For the sample, a laser diffraction-scattering particle size distribution measuring device can be used, with the light source wavelength set to blue and red, to measure the volume-based particle size distribution of the inorganic filler material in a flow cell manner. The average particle size is calculated from the obtained particle size distribution as the median particle size. Examples of laser diffraction-scattering particle size distribution measuring devices include the "LA-960" manufactured by Horiba Manufacturing Co., Ltd.

[0121] (C) The specific surface area of ​​the inorganic filler material is preferably 0.1 m². 2 / g or more, preferably 0.5m 2 / g or more, further preferably 1m 2 / g or more, especially preferably 3m 2 / g or more. Preferably 100m 2 / g or less, preferably 70m 2 / g or less, more preferably 50m 2 / g or less, especially preferably 40m 2 / g or less. (C) The specific surface area of ​​inorganic filler materials can be determined as follows: According to the BET method, nitrogen gas is adsorbed on the sample surface using a specific surface area measuring device (Macsorb HM-1210 manufactured by Mountech), and the specific surface area is calculated using the BET multi-point method.

[0122] From the viewpoint of improving moisture resistance and dispersibility, (C) inorganic filler materials are preferably treated with surface treatment agents. Examples of surface treatment agents include fluorinated silane coupling agents, aminosilane coupling agents, epoxysilane coupling agents, mercaptosilane coupling agents, silane coupling agents, alkoxysilanes, organosilazane compounds, titanate coupling agents, etc. A single surface treatment agent can be used, or two or more can be used in combination.

[0123] Commercially available surface treatment agents include, for example, "KBM403" (3-epoxypropoxypropyltrimethoxysilane) manufactured by Shin-Etsu Chemical Industry Co., Ltd., "KBM803" (3-mercaptopropyltrimethoxysilane) manufactured by Shin-Etsu Chemical Industry Co., Ltd., "KBE903" (3-aminopropyltriethoxysilane) manufactured by Shin-Etsu Chemical Industry Co., Ltd., "KBM573" (N-phenyl-3-aminopropyltrimethoxysilane) manufactured by Shin-Etsu Chemical Industry Co., Ltd., "SZ-31" (hexamethyldisilazane) manufactured by Shin-Etsu Chemical Industry Co., Ltd., "KBM103" (phenyltrimethoxysilane) manufactured by Shin-Etsu Chemical Industry Co., Ltd., "KBM-4803" (long-chain epoxy silane coupling agent) manufactured by Shin-Etsu Chemical Industry Co., Ltd., and "KBM-7103" (3,3,3-trifluoropropyltrimethoxysilane) manufactured by Shin-Etsu Chemical Industry Co., Ltd.

[0124] From the viewpoint of improving the dispersibility of inorganic filler materials, the degree of surface treatment using surface treatment agents is preferably within a specific range. Specifically, 100% by mass of the inorganic filler material is preferably surface treated with 0.2% to 5% by mass of a surface treatment agent, more preferably with 0.2% to 3% by mass of a surface treatment agent, and even more preferably with 0.3% to 2% by mass of a surface treatment agent.

[0125] The degree of surface treatment using surface treatment agents can be evaluated by the carbon content per unit surface area of ​​the inorganic filler material. From the viewpoint of improving the dispersibility of the inorganic filler material, the carbon content per unit surface area of ​​the inorganic filler material is preferably 0.02 mg / m². 2 The above, more preferably 0.1 mg / m 2The above is further preferred to be 0.2 mg / m³. 2 That's all. On the other hand, from the viewpoint of preventing an increase in the melt viscosity of the resin composition layer, 1.0 mg / m³ is preferred. 2 The following is more preferably 0.8 mg / m³ 2 The following is a further preferred value: 0.5 mg / m³ 2 the following.

[0126] (C) The carbon content per unit surface area of ​​the inorganic filler material can be determined after cleaning the surface-treated inorganic filler material with a solvent (e.g., methyl ethyl ketone (MEK)). Specifically, a sufficient amount of MEK is added as a solvent to the surface-treated inorganic filler material, and ultrasonic cleaning is performed at 25°C for 5 minutes. After removing the supernatant and drying the solid components, the carbon content per unit surface area of ​​the inorganic filler material can be determined using a carbon analyzer. A carbon analyzer such as the "EMIA-320V" manufactured by Horiba Corporation can be used.

[0127] Relative to 100% by mass of the non-volatile components of the resin composition, the amount of (C) inorganic filler material is typically 60% by mass or more, preferably 63% by mass or more, more preferably 65% ​​by mass or more, more preferably 90% by mass or less, more preferably 85% by mass or less, and even more preferably 80% by mass or less. When the amount of (C) inorganic filler material is within the above range, it is particularly effective to improve the varnish stability of the resin composition and the insulation reliability and dielectric loss tangent of its cured product, thereby generally resulting in particularly good glass transition temperature, surface roughness, and adhesion of the cured product.

[0128] <(D) Cyclic Phosphazene Compounds> The resin composition according to this embodiment includes a (D) cyclic phosphazene compound as component (D). The (D) cyclic phosphazene compound is represented by formula (1). The (D) cyclic phosphazene compound can generally improve the flame retardancy of the cured resin composition.

[0129] [Chemical Formula 12]

[0130] In equation (1), R 1 and R 2 Each can independently represent a nitro group, any one of (R-1) and (R-2) below; or represent (R-3) below.

[0131] (R-1): An alkyl or alkoxy group having 1 to 8 carbon atoms, optionally substituted with at least one group selected from alkyl and aryl groups having 1 to 6 carbon atoms.

[0132] As conforming to R1 and R 2 Examples of alkyl groups include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, 2-ethylhexyl, benzyl, and 2-phenylethyl. Additionally, as conforming to R... 1 and R 2 Examples of alkoxy groups include methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, sec-butoxy, tert-butoxy, n-pentoxy, n-hexoxy, n-heptoxy, n-octoxy, n-nonoxy, 2-ethylhexoxy, benzyloxy, and 2-phenylethyloxy. Among these, R, classified as (R-1),... 1 and R 2 Preferably, it is methyl, ethyl, n-propyl, benzyl, or methoxy, and more preferably methyl or ethyl.

[0133] (R-2): An aryl or aryloxy group having 6 to 20 carbon atoms, optionally substituted with at least one group selected from alkyl and aryl groups having 1 to 6 carbon atoms.

[0134] As conforming to R 1 and R 2 Examples of aryl groups include phenyl, methylphenyl, dimethylphenyl, ethylphenyl, ethylmethylphenyl, diethylphenyl, n-propylphenyl, isopropylphenyl, isopropylmethylphenyl, isopropylethylphenyl, diisopropylphenyl, n-butylphenyl, sec-butylphenyl, tert-butylphenyl, n-pentylphenyl, n-hexylphenyl, phenylphenyl, naphthyl, anthraceneyl, and phenanthryl. Additionally, as conforming to R... 1 and R 2 Examples of aryloxy groups include phenyloxy, methylphenyloxy, dimethylphenyloxy, ethylphenyloxy, ethylmethylphenyloxy, diethylphenyloxy, n-propylphenyloxy, isopropylphenyloxy, isopropylmethylphenyloxy, isopropylethylphenyloxy, diisopropylphenyloxy, n-butylphenyloxy, sec-butylphenyloxy, tert-butylphenyloxy, n-pentylphenyloxy, n-hexylphenyloxy, phenylphenyloxy, naphthyloxy, anthraceneyloxy, and phenanthreneoxy. Among these, R is classified as (R-2). 1 and R 2 Preferably, it is phenyl, methylphenyl, dimethylphenyl, diethylphenyl, phenylphenyl, naphthyl, and phenyloxy, more preferably phenyl and methylphenyl.

[0135] (R-3): In R 1 and R 2 The saturated or unsaturated cyclic structures formed between the atoms, wherein the cyclic structures are optionally substituted by alkyl or carbonyl groups having 1 to 6 carbon atoms.

[0136] Examples of phosphazene units with a conforming saturated cyclic structure include the repeating unit shown in equation (2-1) and the repeating unit shown in equation (2-2).

[0137] [Chemical Formula 13]

[0138] (In equations (2-1) and (2-2), the symbols L and m have the same meaning as the corresponding symbols in equation (1).)

[0139] Therefore, for example, when m is 0, as examples of phosphazene units with saturated cyclic structures, the repeating units shown in equation (2-1-1) and equation (2-2-1) can be cited.

[0140] [Chemical Formula 14]

[0141] In addition, as an example of a phosphazene unit with a conforming unsaturated cyclic structure, the repeating unit shown in equation (2-3) can be cited.

[0142] [Chemical Formula 15]

[0143] (In equation (2-3), the symbols L and m are synonymous with the symbols in equation (1).)

[0144] Therefore, for example, when m is 0, the repeating unit shown in equation (2-3-1) can be cited as an example of a phosphazene unit with an unsaturated cyclic structure.

[0145] [Chemical Formula 16]

[0146] In equation (1), R 1 and R 2 They can be the same or different. Additionally, multiple R... 1 They can be the same or different. Furthermore, multiple Rs... 2 They can be the same or different.

[0147] In equation (1), L represents a divalent heteroatom. An example of L is the oxygen atom.

[0148] In equation (1), a and b each independently represent integers from 0 to 4. Specifically, a represents the substituent R. 1 The quantity is typically 0 or more, typically 4 or less, and preferably 2 or less. Additionally, b represents the substituent R. 2 The quantity is usually above 0, usually below 4, and preferably below 2.

[0149] In equation (1), m independently represents 0 or 1. Preferably, m is 0.

[0150] As symbols a, b, R 1 R 2 Examples of combinations of L and m can be found in Table 1 below. Among them, combinations 1, 2 and 3 are preferred, and combinations 1 and 2 are more preferred.

[0151] [Table 1] [Table 1. Examples of symbol combinations]

[0152] In formula (1), n ​​represents an integer from 3 to 8. Specifically, n is usually 3 or more, usually 8 or less, and preferably 4 or less. In formula (1), n ​​represents the number of phosphazene units shown in formula (2). Therefore, the (D) cyclic phosphazene compound shown in formula (1) can be a cyclic phosphazene compound with n=3 (trimer), a cyclic phosphazene compound with n=4 (tetramer), a cyclic phosphazene compound with n=5 (pentamer), a cyclic phosphazene compound with n=6 (hexamer), a cyclic phosphazene compound with n=7 (heptamer), or a cyclic phosphazene compound with n=8 (octamer).

[0153] In formula (1), n ​​is preferably small. Therefore, when using two or more (D)-cyclic phosphazene compounds with different n values, it is preferable to use a large quantity of compounds with smaller n. In a preferred example, the amount of compounds with n of 3 or 4 (i.e., trimers and tetramers) is 95% by mass or more relative to 100% of the total amount of (D)-cyclic phosphazene compounds. In a further preferred example, the amount of compounds with n of 3 (i.e., trimers) is 95% by mass or more relative to 100% of the total amount of (D)-cyclic phosphazene compounds.

[0154] In formula (1), the structures of the phosphazene units shown in formula (2) are independent. Therefore, the n phosphazene units contained in one molecule of (D) cyclic phosphazene compound can have the same structure or different structures. Thus, a (D) cyclic phosphazene compound can be a compound in which all phosphazene units are the same, or it can be a compound in which two or more phosphazene units have different structures.

[0155] Specific examples of (D) cyclic phosphazene compounds include: any one of the following: a cyclic triphosphazene compound with n=3 in formula (1), a cyclic tetraphosphazene compound with n=4 in formula (1), a cyclic pentaphosphazene compound with n=5 in formula (1), a cyclic hexaphosphazene compound with n=6 in formula (1), a cyclic heptaphosphazene compound with n=7 in formula (1), or a cyclic octaphosphazene compound with n=8 in formula (1), and is a, b, R. 1 R2 L and m are compounds that are combinations of those in Table 1 above.

[0156] In these specific examples, the phosphazene units contained in one molecule may be different, but are preferably the same. In the preferred specific examples, a, b, and R in formula (2) represent the phosphazene units. 1 R 2 The combination of L and m is the same in any phosphazene unit contained in a molecule. Therefore, as a specific example of a preferred (D) cyclic phosphazene compound, the compounds shown in formulas (1-1) to (1-19) below can be cited. In formulas (1-1) to (1-19), n is synonymous with that in formula (1).

[0157] [Chemical Formula 17]

[0158] [Chemical Formula 18]

[0159] In the specific examples described above, it is preferred to be a cyclotriphosphazene compound of formula (1) with n=3 or a cyclotetraphosphazene compound of formula (1) with n=4, and the compound is a combination of Examples 1, 2 or 3; it is further preferred to be a cyclotriphosphazene compound of formula (1) with n=3 and the compound is a combination of Examples 1 or 2. Therefore, it is preferred to be a compound of formulas (1-1) to (1-3) with n=3 or 4; it is further preferred to be a compound of formulas (1-1) to (1-2) with n=3.

[0160] (D) Cyclic phosphazene compounds can be used alone or in combination of two or more.

[0161] (D) Cyclic phosphazene compounds can have stereoisomers. For example, a cyclic triphosphazene compound with n=3 in formula (1) and which is the compound of Combination Example 1 (i.e., the compound shown in formula (1-1)) is represented by the following formula (1-1-1) if it is shown as having 3 phosphazene units.

[0162] [Chemical Formula 19]

[0163] The compound shown in formula (1-1-1) can have diastereomers. Therefore, when this compound is manufactured, the compound shown in formula (1-1-1) can be obtained as a mixture of these diastereomers. Specifically, the compound shown in formula (1-1-1) is sometimes obtained as a mixture of the cis-cis-cis type compound shown in formula (1-1-2) below (hereinafter sometimes referred to as "cis type") and the trans-cis-trans type compound shown in formula (1-1-3) below (hereinafter referred to as "trans type") in the stereoconformation of adjacent phosphazene units.

[0164] [Chemical Formula 20]

[0165] Such mixtures of diastereomers can be used directly as a mixture, or the cis and trans forms of the compound can be separated and used as individual compounds of each type. Examples of separation methods include, for instance, a combination of separation and filtration utilizing solubility in solvents such as toluene, solvent extraction, recrystallization, and separation using column chromatography.

[0166] Furthermore, (D) cyclic phosphazene compounds in formula (1) with n being 4 or more can possess stereoisomers having multiple diastereomers and enantiomers. These stereoisomers can be used as mixtures containing multiple stereoisomers, or they can be separated and used as single compounds.

[0167] (D) Cyclic phosphazene compounds can be manufactured, for example, by the method described in Japanese Patent Application Publication No. 2022-21767. Alternatively, commercially available (D) cyclic phosphazene compounds are also available. Examples of commercially available (D) cyclic phosphazene compounds include "FP-72TP" (Formula (1-1)) and "B" (Formula (1-19)) manufactured by Fushimi Manufacturing Co., Ltd.

[0168] (D) The cyclic phosphazene compound has a melting point preferably above 260°C, more preferably above 270°C, and even more preferably above 280°C. (D) There is no particular upper limit to the melting point of the cyclic phosphazene compound; for example, it can be below 500°C, below 400°C, below 350°C, etc. (D) The melting point of the cyclic phosphazene compound can be determined using a differential scanning calorimeter by heating from 25°C to 500°C at a heating rate of 20°C / min.

[0169] (D) The cyclic phosphazene compound preferably exhibits specific solubility in cyclohexanone. The solubility of the (D) cyclic phosphazene compound in cyclohexanone can be determined, for example, by performing a first dissolution test, in which the (D) cyclic phosphazene compound is dissolved in 10g of cyclohexanone using ultrasonic treatment at 25°C for 10 minutes. Specifically, the amount of (D) cyclic phosphazene compound dissolved in cyclohexanone after performing the first dissolution test is preferably 0.04g or less, more preferably 0.03g or less, and even more preferably 0.02g or less. The lower limit can be 0.00g or greater than 0.00g.

[0170] The first dissolution test of the (D) cyclic phosphazene compound can be performed as follows: Add 0.5 g of the (D) cyclic phosphazene compound to 10 g of cyclohexanone, and sonicate for 10 minutes while heating at 25°C (the test temperature for the first dissolution test) to dissolve the (D) cyclic phosphazene compound. After the added (D) cyclic phosphazene compound has completely dissolved in cyclohexanone, add another 0.5 g of the (D) cyclic phosphazene compound, and repeat the sonication for 10 minutes. Continue until the (D) cyclic phosphazene compound no longer dissolves in cyclohexanone and precipitation is observed; the cumulative amount added before this point can be considered the amount of (D) cyclic phosphazene compound dissolved in cyclohexanone. Specifically, the first dissolution test can be performed using the method described in the examples below.

[0171] The solubility of the (D) cyclic phosphazene compound in cyclohexanone can be determined, for example, by performing a second dissolution test, in which the (D) cyclic phosphazene compound is dissolved in 10g of cyclohexanone by ultrasonic treatment at 70°C for 10 minutes. Specifically, the amount of (D) cyclic phosphazene compound dissolved in cyclohexanone after performing the second dissolution test is preferably 0.3g or less, more preferably 0.2g or less, and even more preferably 0.1g or less. The lower limit can be 0g or greater than 0g.

[0172] (D) The second dissolution test of the cyclic phosphazene compound can be performed using the same method as the first dissolution test, except that the heating temperature during ultrasonic treatment is changed from 25°C to 70°C. Specifically, the second dissolution test can be performed using the method described in the examples described later.

[0173] When using a (D) cyclic phosphazene compound whose solubility differs little from that measured in the first and second dissolution tests described above, the stability of the varnish can be improved particularly effectively. Specifically, as described below, some solvents, such as cyclohexanone, have high boiling points and are able to dissolve (A) epoxy resin and (B) maleimide well. When the difference in solubility of the (D) cyclic phosphazene compound in the solvent due to dissolution temperature is small, the precipitation of the (D) cyclic phosphazene compound is suppressed after storage of the resin varnish containing this solvent, thus improving the stability of the varnish particularly effectively.

[0174] Preferably, the difference between the amount of solubility measured in the first dissolution test and the amount of solubility measured in the second dissolution test is small. Specifically, the range of the above-mentioned difference in solubility is preferably 0.30 g or less, more preferably 0.20 g or less, and even more preferably 0.10 g or less. The lower limit can be 0.00 g or greater than 0.00 g. When the difference in solubility is within the above range, the varnish stability of the resin composition can be improved particularly effectively.

[0175] (D) Cyclic phosphazene compounds are typically included in the resin composition in a particulate state that is incompatible with resin components other than (D) cyclic phosphazene compounds, and are included in the cured product in a form that maintains this particulate state.

[0176] (D) The average particle size of the cyclic phosphazene compound particles is preferably 1.5 μm or less, more preferably 1.2 μm or less, and even more preferably 1.0 μm or less. The lower limit is not particularly limited, and for example, it can be 0.05 μm or more, 0.1 μm or more, 0.2 μm or more, etc. When the average particle size of the (D) cyclic phosphazene compound particles is within the above range, the resin composition according to this embodiment can be applied to a circuit board with small-pitch circuit wiring. Because the varnish stability of the resin composition according to this embodiment is further improved, the particle size increase of the (D) cyclic phosphazene compound can be suppressed even after long-term storage. Therefore, the resin composition according to this embodiment can be applied to circuit boards with small-pitch circuit wiring not only before storage but also after storage.

[0177] Generally speaking, if the average particle size of the components in a resin varnish decreases, the particles tend to aggregate and precipitate, leading to a decrease in varnish stability. However, after conducting research, the inventors unexpectedly discovered that the varnish stability of the resin composition according to this embodiment is particularly improved when the average particle size of the (D) cyclic phosphazene compound particles is reduced. Specifically, the average particle size of the (D) cyclic phosphazene compound particles is more preferably 0.8 μm or less, 0.6 μm or less, or 0.5 μm or less. Thus, by reducing the average particle size of the (D) cyclic phosphazene compound particles, the resin composition according to this embodiment is particularly suitable for circuit boards with small-pitch circuit wiring, both before and after storage.

[0178] (D) The maximum particle size of the cyclic phosphazene compound is preferably 20 μm or less, more preferably 15 μm or less, even more preferably 12 μm or less, even more preferably 9 μm or less, even more preferably 8 μm or less, even more preferably 7 μm or less, and even more preferably 6 μm or less. The lower limit is not particularly limited, and for example, it can be 0.1 μm or more, 0.5 μm or more, 1 μm or more, etc. When the maximum particle size of the cyclic phosphazene compound is within the above-mentioned range, the resin composition according to this embodiment can be applied to circuit boards with small-pitch circuit wiring. Furthermore, the resin composition according to the embodiment can be applied to circuit boards with small-pitch circuit wiring not only before storage but also after storage.

[0179] The average and maximum particle sizes of (D) cyclic phosphazene compounds can be determined using laser diffraction / scattering based on the Mie scattering theory. Specifically, the particle size distribution of (D) cyclic phosphazene compounds can be prepared on a volume basis using a laser diffraction-scattering particle size distribution measuring device. Furthermore, the median particle size D50 of this particle size distribution can be used as the average particle size, and the maximum particle size D100 of this particle size distribution can be used as the maximum particle size. The particle size distribution of (D) cyclic phosphazene compounds can be determined using the same method as that used for the particle size distribution of (C) inorganic filler materials.

[0180] The ratio of the average particle size of the cyclic phosphazene compound (D) to the average particle size of the inorganic filler (C) is preferably within a specific range. Specifically, the average particle size of the cyclic phosphazene compound (D) is set as D. a (Unit: μm), and set the average particle size of (C) inorganic filler material as D. b (Unit: μm) D a With D b The ratio of D a / D bThe range is preferably 10 or less, more preferably 5 or less, even more preferably 3 or less, even more preferably 2 or less, even more preferably 1.5 or less, even more preferably 1.2 or less, and preferably 0.1 or more, more preferably 0.2 or more, and even more preferably 0.3 or more. The above-mentioned average particle size ratio D a / D b Within the aforementioned range, it is preferable to apply the resin composition according to this embodiment to a circuit board having circuit wiring with small spacing. Furthermore, the aforementioned average particle size ratio D... a / D b Within the aforementioned range, the resin composition according to this embodiment further improves the stability of the varnish, thus suppressing the precipitation of components of the resin composition (resin varnish) even after prolonged storage. Therefore, the resin composition according to this embodiment can be applied to circuit boards with small-pitch circuit wiring not only before storage but also after storage.

[0181] The amount of (D) cyclic phosphazene compound relative to 100% by mass of the non-volatile components of the resin composition 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, particularly preferably 0.8% by mass or more, preferably 5% by mass or less, more preferably 3% by mass or less, and even more preferably 2% by mass or less. When the amount of (D) cyclic phosphazene compound is within the above range, the varnish stability of the resin composition and the insulation reliability and dielectric loss tangent of the cured product can be improved particularly effectively, and the glass transition temperature, surface roughness and adhesion of the cured product can generally be made particularly good.

[0182] The amount of (D) cyclic phosphazene compound relative to 100% by mass of the resin component in the resin composition is preferably 0.1% by mass or more, more preferably 1% by mass or more, further preferably 2% by mass or more, particularly preferably 2.5% by mass or more, preferably 20% by mass or less, more preferably 10% by mass or less, and further preferably 5% by mass or less. When the amount of (D) cyclic phosphazene compound is within the above range, the varnish stability of the resin composition and the insulation reliability and dielectric loss tangent of the cured product can be improved particularly effectively, and the glass transition temperature, surface roughness and adhesion of the cured product can generally be made particularly good.

[0183] As described above, the (D) cyclic phosphazene compound can be included in the resin composition in particulate form, and therefore it is preferable to use it in a specific ratio relative to the (C) inorganic filler material, which is also included in the resin composition in particulate form. Specifically, the amount of the (D) cyclic phosphazene compound relative to 100% by mass of the (C) inorganic filler material is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, further preferably 0.5% by mass or more, preferably 5% by mass or less, more preferably 3% by mass or less, further preferably 2% by mass or less, and even more preferably 1% by mass or less.

[0184] The total amount of (A) epoxy resin, (B) maleimide resin, (C) inorganic filler and (D) cyclic phosphazene compound relative to 100% by mass of the non-volatile components of the resin composition is preferably 65% ​​by mass or more, more preferably 70% by mass or more, further preferably 75% by mass or more, particularly preferably 80% by mass or more, and usually 100% by mass or less.

[0185] <(E) Any curable resin> The resin composition according to this embodiment may include (E) any curable resin as an arbitrary component. The (E) any curable resin as component (E) does not contain substances belonging to components (A) to (D) above. (E) any curable resin refers to a curable resin other than (A) epoxy resin and (B) maleimide resin. (E) any curable resin may be used alone or in combination of two or more.

[0186] As any curable resin (E), examples include curing agents. A curing agent refers to a curable resin that can react with (A) epoxy resin to cure the resin composition. A curing agent may be used alone or in combination of two or more.

[0187] Examples of curing agents include reactive ester resins, phenolic resins, carbodiimide resins, cyanate ester resins, benzoxazine resins, acid anhydride resins, amine resins, and thiol resins. Among these, reactive ester resins, phenolic resins, and carbodiimide resins are preferred; reactive ester resins are more preferred. Therefore, the curing agent preferably comprises one or more selected from reactive ester resins, phenolic resins, and carbodiimide resins; more preferably, it comprises an reactive ester resin.

[0188] As an active ester resin, a resin having one or more, preferably two or more, active ester groups per molecule can be used. Among these, resins having two or more highly reactive ester groups per molecule, such as phenolic esters, thiophenolic esters, N-hydroxylamine esters, and heterocyclic hydroxyl compounds, are preferred as active ester resins.

[0189] Reactive ester resins are preferably obtained through the condensation reaction of carboxylic acid compounds and / or thiocarboxylic acid compounds with hydroxyl compounds and / or thiols. Particularly from the viewpoint of improving heat resistance, reactive ester resins obtained from carboxylic acid compounds and hydroxyl compounds are preferred, and reactive ester resins obtained from carboxylic acid compounds and phenolic compounds and / or naphthol compounds are more preferred. Examples of carboxylic acid compounds include, for instance, benzoic acid, acetic acid, succinic acid, maleic acid, itaconic acid, phthalic acid, isophthalic acid, terephthalic acid, and pyromellitic acid. Examples of phenolic or naphthol compounds include hydroquinone, resorcinol, bisphenol A, bisphenol F, bisphenol S, phenolphthalein, methylated bisphenol A, methylated bisphenol F, methylated bisphenol S, phenol, o-cresol, m-cresol, p-cresol, catechol, α-naphthol, β-naphthol, 1,5-dihydroxynaphthol, 1,6-dihydroxynaphthol, 2,6-dihydroxynaphthol, dihydroxybenzophenone, trihydroxybenzophenone, tetrahydroxybenzophenone, phloroglucinol, pyroglucinol, dicyclopentadiene-type diphenol compounds, and linear phenolic resins. Here, "dicyclopentadiene-type diphenol compounds" refers to diphenol compounds obtained by condensing one molecule of dicyclopentadiene with two molecules of phenol.

[0190] Specifically, the preferred active ester resins are dicyclopentadiene-type active ester resins, naphthalene-type active ester resins containing a naphthalene structure, active ester resins containing acetylated linear phenolic resins, and active ester resins containing benzoylated linear phenolic resins; more preferably, dicyclopentadiene-type and naphthalene-type active ester resins; and even more preferably, dicyclopentadiene-type active ester resins. As a dicyclopentadiene-type active ester resin, an active ester resin containing a dicyclopentadiene-type diphenol structure is preferred.

[0191] Regarding commercially available reactive ester resins, examples include "EXB9451", "EXB9460", "EXB9460S", "EXB-8000L", "EXB-8000L-65M", "EXB-8000L-65TM", "HPC-8000L-65TM", "HPC-8000L-65MT", "HPC-8000", "HPC-8000-65T", "EXB-8000H", and "NE-V-1100-70T" (manufactured by DIC Corporation) as reactive ester resins containing a naphthalene structure; and "EXB-8100L-65T", "EXB-8150-", etc. as reactive ester resins containing a naphthalene structure. Examples of active ester resins containing phosphorus include “60T”, “EXB-8150-62T”, “EXB-9416-70BK”, “HPC-8150-62T”, and “HPC-8151-62T” (manufactured by DIC Corporation); examples of active ester resins containing phosphorus include “EXB9401” (manufactured by DIC Corporation); examples of active ester resins containing acetylated linear phenolic resins include “DC808” (manufactured by Mitsubishi Chemical Corporation); examples of active ester resins containing benzoylated linear phenolic resins include “YLH1026”, “YLH1030”, and “YLH1048” (manufactured by Mitsubishi Chemical Corporation); and examples of active ester resins containing styrene and naphthalene structures include “PC1300-02-65MA” (manufactured by Air Water Corporation).

[0192] The amount of active ester resin relative to 100% by mass of the non-volatile components of the resin composition is preferably 1% by mass or more, more preferably 2% by mass or more, further preferably 5% by mass or more, particularly preferably 11% by mass or more, preferably 30% by mass or less, more preferably 25% by mass or less, further preferably 20% by mass or less, and particularly preferably 18% by mass or less. When the amount of active ester resin is within the above range, the varnish stability of the resin composition and the insulation reliability and dielectric loss tangent of the cured product can be improved particularly effectively, and the glass transition temperature, surface roughness, and adhesion of the cured product are generally particularly good.

[0193] Relative to 100% by mass of the resin component in the resin composition, the amount of active ester resin is preferably 10% by mass or more, more preferably 20% by mass or more, further preferably 30% by mass or more, particularly preferably 35% by mass or more, preferably 70% by mass or less, more preferably 60% by mass or less, and further preferably 50% by mass or less. When the amount of active ester resin is within the above range, the varnish stability of the resin composition and the insulation reliability and dielectric loss tangent of the cured product can be improved particularly effectively, and the glass transition temperature, surface roughness, and adhesion of the cured product are generally particularly good.

[0194] As phenolic resins, resins having one or more, preferably two or more, hydroxyl groups (phenolic hydroxyl groups) bonded to aromatic rings such as benzene rings or naphthalene rings in one molecule can be used. From the viewpoint of heat resistance and water resistance, phenolic resins having a phenolic structure are preferred. Furthermore, from the viewpoint of adhesion, nitrogen-containing phenolic resins are preferred, and phenolic resins containing a triazine skeleton are more preferred. Among these, from the viewpoint of highly satisfying heat resistance, water resistance, and adhesion, linear phenolic resins containing a triazine skeleton are preferred.

[0195] Specific examples of phenolic resins include: "MEH-7700", "MEH-7810", "MEH-7851", and "MEH-8000H" manufactured by Meiwa Chemical Co., Ltd.; "NHN", "CBN", "GPH", and "GPH-65" manufactured by Nippon Kayaku Co., Ltd.; and "SN-170", "SN-180", "SN-190", "SN-475", "SN-485", "SN-495", and "SN-495V" manufactured by Nippon Steel Chemical Materials Co., Ltd. "SN-375", "SN-395"; "TD-2090", "TD-2090-60M", "LA-7052", "LA-7054", "LA-1356", "LA-3018", "LA-3018-50P", "LA-1356", "TD2090", "TD-2090-60M" manufactured by DIC Company; "GDP-6115L", "GDP-6115H", "ELPC 75" manufactured by Qunrong Chemical Company, etc.

[0196] The amount of phenolic resin relative to 100% by mass of the non-volatile components of the resin composition is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, even more preferably 0.5% by mass or more, preferably 20% by mass or less, more preferably 10% by mass or less, and even more preferably 5% by mass or less. When the amount of phenolic resin is within the above range, the varnish stability of the resin composition and the insulation reliability and dielectric loss tangent of the cured product can be improved particularly effectively, and the glass transition temperature, surface roughness, and adhesion of the cured product are generally particularly good.

[0197] The amount of phenolic resin relative to 100% by mass of the resin component in the resin composition is preferably 0.1% by mass or more, more preferably 1% by mass or more, further preferably 2% by mass or more, particularly preferably 3.5% by mass or more, preferably 30% by mass or less, more preferably 20% by mass or less, further preferably 10% by mass or less, and particularly preferably 5% by mass or less. When the amount of phenolic resin is within the above range, the varnish stability of the resin composition and the insulation reliability and dielectric loss tangent of the cured product can be improved particularly effectively, and the glass transition temperature, surface roughness, and adhesion of the cured product are generally particularly good.

[0198] As a carbodiimide-based resin, resins having one or more, preferably two or more, carbodiimide structures within one molecule can be used. Specific examples of carbodiimide-based resins include: aliphatic dicarbodiimides such as tetramethylene-bis(tert-butylcarbodiimide) and cyclohexane-bis(methylene-tert-butylcarbodiimide); aromatic dicarbodiimides such as phenylene-bis(xylylcarbodiimide); aliphatic polycarbodiimides such as polyhexamethylenecarbodiimide, polytrimethylhexamethylenecarbodiimide, polycyclohexylcarbodiimide, poly(methylene biscyclohexylcarbodiimide), and poly(isophoronecarbodiimide); poly(phenylenecarbodiimide), poly(... Aromatic polycarbodiimides such as naphthylcarbodiimide, poly(tolylcarbodiimide), poly(methyldiisopropylphenylcarbodiimide), poly(triethylphenylcarbodiimide), poly(diethylphenylcarbodiimide), poly(triisopropylphenylcarbodiimide), poly(diisopropylphenylcarbodiimide), poly(xylylcarbodiimide), poly(tetramethylxylylcarbodiimide), poly(methylenediphenylcarbodiimide), and poly[methylenebis(methylphenyl)carbodiimide] are also included. Commercially available carbodiimide resins include, for example, "CARBODILITE V-02B", "CARBODILITE A", "CARBODILITE V-03", "CARBODILITE V-04K", "CARBODILITE V-05", "CARBODILITE V-07", and "CARBODILITE V-09" manufactured by Nisshinbo Chemical Co., Ltd.; and "Stabaxol P", "Stabaxol P400", and "Hycasyl510" manufactured by LANXESS Co., Ltd.

[0199] The amount of carbodiimide resin relative to 100% by mass of the non-volatile components of the resin composition is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, even more preferably 0.2% by mass or more, preferably 10% by mass or less, more preferably 5% by mass or less, and even more preferably 2% by mass or less. When the amount of carbodiimide resin is within the above range, the varnish stability of the resin composition and the insulation reliability and dielectric loss tangent of the cured product can be improved particularly effectively, and the glass transition temperature, surface roughness, and adhesion of the cured product are generally particularly good.

[0200] The amount of carbodiimide resin relative to 100% by mass of the resin component in the resin composition is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, even more preferably 1% by mass or more, preferably 20% by mass or less, more preferably 10% by mass or less, and even more preferably 5% by mass or less. When the amount of carbodiimide resin is within the above range, the varnish stability of the resin composition and the insulation reliability and dielectric loss tangent of the cured product can be improved particularly effectively, and the glass transition temperature, surface roughness, and adhesion of the cured product are generally particularly good.

[0201] As a cyanate ester resin, a resin having one or more, preferably two or more, cyanate ester groups in one molecule can be used. Examples of difunctional cyanate ester resins include bisphenol A dicyanate, polyphenol cyanate, oligomeric (3-methylene-1,5-phenylene cyanate), 4,4'-methylenebis(2,6-dimethylphenyl cyanate), 4,4'-ethoxydiphenyl dicyanate, hexafluorobisphenol A dicyanate, 2,2-bis(4-cyanoxy)phenylpropane, 1,1-bis(4-cyanoxyphenylmethane), bis(4-cyanoxy-3,5-dimethylphenyl)methane, 1,3-bis(4-cyanoxyphenyl-1-(methylethoxy))benzene, bis(4-cyanoxyphenyl)sulfide, and bis(4-cyanoxyphenyl) ether; multifunctional cyanate ester resins derived from linear phenolic resins and cresol phenolic varnish resins; and prepolymers obtained by partially triazinizing these cyanate ester resins. Specific examples of cyanate ester resins include Arxada's "PT30" and "PT60" (both linear phenolic resin-type multifunctional cyanate ester resins), "BA230", and "BA230S75" (prepolymers obtained by triazinization of part or all of bisphenol A dicyanate to form trimers).

[0202] As benzoxazine resins, resins having one or more, preferably two or more, benzoxazine rings within one molecule can be used. Specific examples of benzoxazine resins include "JBZ-OP100D" and "ODA-BOZ" manufactured by JFE Chemical Co., Ltd.; "HFB2006M" manufactured by Showa Polymer Co., Ltd.; and "Pd", "Fa", and "ALP-d" manufactured by Shikoku Chemical Industry Co., Ltd.

[0203] As an anhydride-based resin, resins having one or more, preferably two or more, anhydride groups within one molecule can be used. Specific examples of anhydride-based resins include phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, methylnadic anhydride, hydrogenated methylnadic anhydride, trialkyltetrahydrophthalic anhydride, dodecenylsuccinic anhydride, 5-(2,5-dioxotetrahydro-3-furanyl)-3-methyl-3-cyclohexene-1,2-dicarboxylic anhydride, trimellitic anhydride, pyromellitic anhydride, and diphenylene oxide. Polymer anhydrides such as methyl ketone tetracarboxylic dianhydride, biphenyl tetracarboxylic dianhydride, naphthalene tetracarboxylic dianhydride, oxophthalic dianhydride, 3,3'-4,4'-diphenyl sulfone tetracarboxylic 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(trimethoxybenzoic anhydride ester), and styrene-maleic acid resin obtained by copolymerizing styrene and maleic acid. Commercially available anhydride resins include, for example, "HNA-100", "MH-700", "MTA-15", "DDSA", and "OSA" manufactured by Shin Nippon Rika Co., Ltd.; "YH-306" and "YH-307" manufactured by Mitsubishi Chemical Co., Ltd.; "HN-2200" manufactured by Risenauco Co., Ltd.; and "EF-30", "EF-40", "EF-60", and "EF-80" manufactured by Cray Valley Co., Ltd.

[0204] As an amine resin, a resin having one or more, preferably two or more, amino groups within one molecule can be used. Examples of amine resins include aliphatic amines, polyether amines, alicyclic amines, and aromatic amines, with aromatic amines being preferred. The amine resin is preferably a primary or secondary amine, more preferably a primary amine. Specific examples of amine resins include 4,4'-methylenebis(2,6-dimethylaniline), 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenyl sulfone, 3,3'-diaminodiphenyl sulfone, m-phenylenediamine, m-phenylenediamine, diethyltoluenediamine, 4,4'-diaminodiphenyl ether, 3,3'-dimethyl-4,4'-diaminobiphenyl, 2,2'-dimethyl-4,4'-diaminobiphenyl, 3,3'-dihydroxybiphenylamine, and 2,2-bis(3-amino-4-hydroxybenzene). 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, etc. Commercially available amine resins include, for example, "SEIKACURE-S" manufactured by SEIKA Corporation; "KAYABOND C-200S", "KAYABOND C-100", "KAYAHARD AA", "KAYAHARD AB", and "KAYAHARD AS" manufactured by Nippon Kayaku Co., Ltd.; "Epicure W" manufactured by Mitsubishi Chemical Co., Ltd.; and "DTDA" manufactured by Sumitomo Seika Co., Ltd.

[0205] Examples of thiol-based resins include trimethylolpropane tris(3-mercaptopropionate), pentaerythritol tetra(3-mercaptobutyrate), and tris(3-mercaptopropyl)isocyanurate.

[0206] The equivalent amount of active groups in the 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 equivalent amount of active groups indicates the mass of resin per equivalent of active groups. Furthermore, the active groups in the curing agent refer to groups capable of reacting with the epoxy groups of (A) epoxy resin, and examples include, for instance, active ester groups, phenolic hydroxyl groups, and carbodiimide groups.

[0207] The range of the weight-average molecular weight (Mw) of the curing agent can be the same as the range of the weight-average molecular weight (Mw) of (A) epoxy resin.

[0208] The equivalent ratio (active groups / epoxy groups) of the active groups of the curing agent to the epoxy groups of (A) epoxy resin is preferably 0.1 or more, more preferably 0.5 or more, further preferably 1.0 or more, preferably 5 or less, more preferably 3 or less, and further preferably 2 or less. The aforementioned equivalent ratio (active groups / epoxy groups) can be obtained by dividing the "number of active groups of the curing agent" in the resin composition by the "number of epoxy groups of (A) epoxy resin". The "number of epoxy groups of (A) epoxy resin" in the resin composition represents the sum of all values ​​obtained by dividing the mass of the non-volatile component of the epoxy resin present in the resin composition by its epoxy equivalent. Furthermore, the "number of active groups of the curing agent" in the resin composition represents the sum of all values ​​obtained by dividing the mass of the non-volatile component of the curing agent present in the resin composition by its active group equivalent. When the equivalence ratio (active group / epoxy group) is within the above range, the varnish stability of the resin composition and the insulation reliability and dielectric loss tangent of the cured product can be improved particularly effectively, and the glass transition temperature, surface roughness and adhesion of the cured product can usually be made particularly good.

[0209] The amount of curing agent relative to 100% by mass of the non-volatile components of the resin composition is preferably 2% by mass or more, more preferably 5% by mass or more, even more preferably 10% by mass or more, preferably 30% by mass or less, more preferably 25% by mass or less, and even more preferably 20% by mass or less. When the amount of curing agent is within the above range, the varnish stability of the resin composition and the insulation reliability and dielectric loss tangent of the cured product can be improved particularly effectively, and the glass transition temperature, surface roughness, and adhesion of the cured product can generally be made particularly good.

[0210] The amount of curing agent relative to 100% by mass of the resin component in the resin composition is preferably 20% by mass or more, more preferably 30% by mass or more, even more preferably 40% by mass or more, preferably 70% by mass or less, more preferably 60% by mass or less, and even more preferably 50% by mass or less. When the amount of curing agent is within the above range, the varnish stability of the resin composition and the insulation reliability and dielectric loss tangent of the cured product can be improved particularly effectively, and the glass transition temperature, surface roughness, and adhesion of the cured product can generally be made particularly good.

[0211] As any curable resin (E), examples include free radical polymerizable resins. Free radical polymerizable resins contain non-aromatic carbon-carbon unsaturated bonds and can undergo free radical polymerization. Free radical polymerizable resins can undergo free radical polymerization between themselves, or between themselves and (B) maleimide resin.

[0212] As a free radical polymerizable resin, a resin containing polymerizable unsaturated groups can be used, for example. Polymerizable unsaturated groups refer to groups containing non-aromatic carbon-carbon unsaturated bonds, and examples include unsaturated hydrocarbon groups such as vinyl, allyl, 1-propenyl, 3-cyclohexenyl, 3-cyclopentenyl, 2-vinylphenyl, 3-vinylphenyl, and 4-vinylphenyl; and α,β-unsaturated carbonyl groups such as acryloyl and methacryloyl. Free radical polymerizable resins preferably have two or more polymerizable unsaturated groups.

[0213] Examples of free radical polymerizable resins include (meth)acrylic acid-based free radical polymerizable resins, styrene-based free radical polymerizable resins, and allyl-based free radical polymerizable resins. A single free radical polymerizable resin can be used alone, or two or more can be used in combination.

[0214] As a (meth)acrylic acid-based free radical polymerizable resin, a resin having one or more, preferably two or more, acryloyl and / or methacryloyl groups in one molecule can be used. Examples of low molecular weight (molecular weight less than 1000) aliphatic (meth)acrylate compounds, such as cyclohexane-1,4-diethanol di(meth)acrylate, cyclohexane-1,3-diethanol di(meth)acrylate, tricyclodecane-diethanol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,8-octanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, 1,10-decanediol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, trimethylolethane tri(meth)acrylate, glycerol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, etc.; dioxanediol di(meth)acrylate, 3,6-dioxane-1,8-octanediol di(meth)acrylate, etc. Low molecular weight (molecular weight less than 1000) ether-containing (meth)acrylate compounds such as di(meth)acrylate of alcohols, 3,6,9-trioxaundecane-1,11-diol di(meth)acrylate, polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, 9,9-bis[4-(2-acryloyloxyethoxy)phenyl]fluorene, ethoxylated bisphenol A di(meth)acrylate, propoxylated bisphenol A di(meth)acrylate, etc.; low molecular weight (molecular weight less than 1000) isocyanurate-containing (meth)acrylate compounds such as tri(3-hydroxypropyl)isocyanurate tri(meth)acrylate, tri(2-hydroxyethyl)isocyanurate tri(meth)acrylate, ethoxylated isocyanuric acid tri(meth)acrylate, etc.; high molecular weight (molecular weight greater than 1000) acrylate compounds such as (meth)acrylate-modified polyphenylene ether resin, etc. Here, the term "(meth)acrylic acid" includes acrylic acid, methacrylic acid, and combinations thereof. Additionally, the term "(meth)acrylate" includes acrylates, methacrylates, and combinations thereof. Commercially available (meth)acrylic acid-based free radical polymerizable resins include, for example, "A-DOG" (dioxanediol diacrylate) manufactured by Shin-Nakamura Chemical Industry Co., Ltd., "DCP-A" (tricyclodecanediethanol diacrylate), "DCP" (tricyclodecanediethanol dimethacrylate), BPE-1300N (ethoxylated bisphenol A dimethacrylate), "KAYARAD R-684" (tricyclodecanediethanol diacrylate), "KAYARAD R-604" (dioxanediol diacrylate) manufactured by Nippon Kayaku Co., Ltd., and "SA9000" and "SA9000-111" (methacrylic acid modified polyphenylene ether) manufactured by SABIC.

[0215] As a styrene-based free radical polymerizable resin, a resin having one or more, preferably two or more, vinyl groups directly bonded to aromatic carbon atoms in one molecule can be used. Examples of styrene-based free radical polymerizable resins include low molecular weight (molecular weight less than 1000) styrene-based compounds such as divinylbenzene, 2,4-divinyltoluene, 2,6-divinylnaphthalene, 1,4-divinylnaphthalene, 4,4'-divinylbiphenyl, 1,2-bis(4-vinylphenyl)ethane, 2,2-bis(4-vinylphenyl)propane, and bis(4-vinylphenyl) ether; and high molecular weight (molecular weight 1000 or more) styrene-based compounds such as vinylbenzyl-modified polyphenylene ether resin and styrene-divinylbenzene copolymer. Commercially available styrene-based free radical polymerizable resins include, for example, "ODV-XET(X03)", "ODV-XET(X04)", and "ODV-XET(X05)" (styrene-divinylbenzene copolymer) manufactured by Nippon Steel Chemical Materials Co., Ltd., and "OPE-2St 1200" and "OPE-2St 2200" (vinyl benzyl modified polyphenylene ether resin) manufactured by Mitsubishi Gas Chemical Co., Ltd.

[0216] As an allyl-based free radical polymerizable resin, resins having one or more, preferably two or more, allyl groups in one molecule can be used. Examples of allyl-based free radical polymerizable resins include aromatic carboxylic acid allyl ester compounds such as diallyl diphenate, triallyl trimellitate, diallyl phthalate, diallyl isophthalate, diallyl terephthalate, diallyl 2,6-naphthalenedicarboxylate, and diallyl 2,3-naphthalenedicarboxylate; isocyanurate allyl ester compounds such as 1,3,5-triallyl isocyanurate and 1,3-diallyl-5-glycidyl isocyanurate; aromatic allyl compounds containing ethers such as 1,3,5-triallyl etherbenzene; and allylsilane compounds such as diallyl diphenylsilane. Commercially available allyl-based free radical polymerizable resins include, for example, "TAIC" (1,3,5-triallyl isocyanurate) manufactured by Nippon Chemical Co., Ltd., "DAD" (diallyl biphenylcarboxylate) manufactured by Nisshoku Techno Fine Chemical Co., Ltd., "TRIAM-705" (triallyl trimellitate) manufactured by Fujifilm and Kouichi Pharmaceutical Co., Ltd., "DAND" (2,3-diallyl naphtholic acid) manufactured by Nisshoku Techno Fine Chemical Co., Ltd., and "ALP-d" (bis[3-allyl-4-(3,4-dihydro-2H-1,3-benzoxazin-3-yl)phenyl]methane) manufactured by Shikoku Chemical Industry Co., Ltd.

[0217] Free radical polymerizable resins may contain active groups capable of reacting with epoxy groups. Free radical polymerizable resins containing active groups can function as both curing agents and free radical polymerizable resins. Examples of resins capable of functioning as both curing agents and free radical polymerizable resins include resins containing both allyl and active ester groups, such as the active ester resin B and free radical polymerizable resin A used in the examples described later.

[0218] The equivalent amount of polymerizable unsaturated groups in the free radical polymerizable resin is preferably 20 g / eq. to 3000 g / eq., more preferably 50 g / eq. to 2500 g / eq., even more preferably 70 g / eq. to 2000 g / eq., and particularly preferably 90 g / eq. to 1500 g / eq. The equivalent amount of polymerizable unsaturated groups indicates the mass of resin per equivalent of polymerizable unsaturated groups.

[0219] The weight-average molecular weight (Mw) of the free radical polymerizable resin is preferably 40,000 or less, more preferably 10,000 or less, even more preferably 5,000 or less, and particularly preferably 3,000 or less. The lower limit is not particularly limited; for example, it can be 150 or more.

[0220] The amount of free radical polymerizable resin relative to 100% by mass of the non-volatile components of the resin composition is preferably 0.1% by mass or more, more preferably 1% by mass or more, further preferably 3% by mass or more, particularly preferably 4% by mass or more, preferably 30% by mass or less, more preferably 20% by mass or less, further preferably 10% by mass or less, and particularly preferably 8% by mass or less. When the amount of free radical polymerizable resin is within the above range, the varnish stability of the resin composition and the insulation reliability and dielectric loss tangent of the cured product can be improved particularly effectively, and the glass transition temperature, surface roughness, and adhesion of the cured product can generally be made particularly good.

[0221] Relative to 100% by mass of the resin component in the resin composition, the amount of free radical polymerizable resin is preferably 1% by mass or more, more preferably 5% by mass or more, further preferably 10% by mass or more, particularly preferably 15% by mass or more, preferably 50% by mass or less, more preferably 40% by mass or less, further preferably 30% by mass or less, and particularly preferably 25% by mass or less. When the amount of free radical polymerizable resin is within the above range, the varnish stability of the resin composition and the insulation reliability and dielectric loss tangent of the cured product can be improved particularly effectively, thereby generally resulting in particularly good glass transition temperature, surface roughness, and adhesion of the cured product.

[0222] Relative to 100% by mass of the non-volatile components of the resin composition, the amount of (E) any curable resin is preferably 1% by mass or more, more preferably 5% by mass or more, even more preferably 10% by mass or more, preferably 30% by mass or less, more preferably 25% by mass or less, and even more preferably 20% by mass or less. When the amount of (E) any curable resin is within the above range, the varnish stability of the resin composition and the insulation reliability and dielectric loss tangent of the cured product can be improved particularly effectively, and the glass transition temperature, surface roughness and adhesion of the cured product can generally be made particularly good.

[0223] Relative to 100% by mass of the resin component in the resin composition, the amount of (E) any curable resin is preferably 10% by mass or more, more preferably 20% by mass or more, further preferably 30% by mass or more, particularly preferably 40% by mass or more, preferably 70% by mass or less, more preferably 60% by mass or less, and further preferably 55% by mass or less. When the amount of (E) any curable resin is within the above range, the varnish stability of the resin composition and the insulation reliability and dielectric loss tangent of the cured product can be improved particularly effectively, and the glass transition temperature, surface roughness and adhesion of the cured product can generally be made particularly good.

[0224] <(F) Polymer Resins> The resin composition according to this embodiment may include (F) polymer resin as an optional component. The (F) polymer resin, as component (F), does not contain resins belonging to components (A) to (E) described above. The (F) polymer resin is generally thermoplastic. Furthermore, the (F) polymer resin is generally included in the resin composition in a state compatible with curable resins such as (A) epoxy resin and (B) maleimide resin, and is included in the cured product in this compatible state. One type of (F) polymer resin may be used alone, or two or more types may be used in combination.

[0225] (F) Polymer resins typically have large molecular weights. Specifically, the weight-average molecular weight (Mw) of the (F) polymer resin is preferably greater than 5,000, more preferably 8,000 or more, even more preferably 10,000 or more, even more preferably 20,000 or more, preferably 100,000 or less, more preferably 70,000 or less, even more preferably 60,000 or less, and even more preferably 50,000 or less. The weight-average molecular weight (Mw) can be determined by gel permeation chromatography (GPC) using a polystyrene equivalent.

[0226] Examples of (F) polymer resins include phenoxy resins, polyimide resins, polyvinyl acetal resins, polystyrene resins, polyolefin resins, polybutadiene resins, polyamide-imide resins, polyethersulfone resins, polysulfone resins, polyetherimide resins, polyphenylene ether resins, polycarbonate resins, polyetheretherketone resins, and polyester resins. Among these, phenoxy resins are preferred.

[0227] Examples of phenoxy resins include those having one or more skeletons selected from the following: bisphenol A skeleton, bisphenol F skeleton, bisphenol S skeleton, bisphenol acetophenone skeleton, phenolic skeleton, biphenyl skeleton, fluorene skeleton, dicyclopentadiene skeleton, norbornene skeleton, naphthalene skeleton, anthracene skeleton, adamantane skeleton, terpene skeleton, and trimethylcyclohexane skeleton. The terminal group of the phenoxy resin can be any functional group such as a phenolic hydroxyl group or an epoxy group. Specific examples of phenoxy resins include Mitsubishi Chemical Corporation's "1256" and "4250" (both containing a bisphenol A skeleton); Mitsubishi Chemical Corporation's "YX8100" (containing a bisphenol S skeleton); Mitsubishi Chemical Corporation's "YX7800BH40" (containing a fluorene skeleton); Mitsubishi Chemical Corporation's "YX6954" (containing a bisphenol acetophenone skeleton); and Nippon Steel Chemical Materials Co., Ltd. The "FX280" and "FX293" manufactured by the company; and the "YL7500BH30", "YX6954BH30", "YX7553", "YX7553BH30", "YL7769BH30", "YL6794", "YL7213", "YL7290", "YL7482", "YL7891BH30", "YL7891T30" and "YL9142T30" manufactured by Mitsubishi Chemical Corporation, etc.

[0228] Specific examples of polyimide resins include "PIAD200" manufactured by Arakawa Chemical Co., Ltd., "SLK-6100" manufactured by Shin-Etsu Chemical Industry Co., Ltd., and "RIKACOAT SN20" and "RIKACOAT PN20" manufactured by Shin Nippon Rika Co., Ltd. Specific examples of polyimide resins include linear polyimide resins obtained by reacting difunctional hydroxyl-terminated polybutadiene, diisocyanate compounds, and tetrabasic anhydrides (the polyimide resin described in Japanese Patent Application Publication No. 2006-37083), and modified polyimide resins containing a polysiloxane backbone (the polyimide resins described in Japanese Patent Application Publication Nos. 2002-12667 and 2000-319386, etc.).

[0229] Examples of polyvinyl acetal resins include polyvinyl formal resin and polyvinyl butyral resin, with polyvinyl butyral resin being the most preferred. Specific examples of polyvinyl acetal resins include the S-LEC BH series, BX series (e.g., BX-5Z), KS series (e.g., KS-1), BL series, and BM series manufactured by Sekisui Chemicals Co., Ltd.

[0230] Examples of polystyrene-based resins include unmodified polystyrene resins, modified polystyrene resins containing oxazoline groups, and styrene block copolymers. Examples of styrene block copolymers include styrene-isoprene-styrene block copolymers (SIS resin), styrene-ethylene / butene-styrene block copolymers (SEBS resin), styrene-ethylene / propylene-styrene block copolymers (SEPS resin), styrene-butadiene-styrene block copolymers (SBS resin), and styrene-isobutylene-styrene block copolymers (SIBS resin). Specific examples of polystyrene-based resins include: Nippon Shokubai's "PX3-RP-37" and "RP-RX-61" (modified polystyrene resins containing oxazoline groups); Kuraray's "HYBRAR 5125" (SIS resin); Asahi Kasei's "S1611" (SEBS resin); Asahi Kasei's "H1041," "Tuftec H1043," "Tuftec P2000," and "Tuftec MP10" (hydrogenated styrene-based polymer resins); Daicel's "Epofriend AT501" and "CT310" (epoxidized styrene-butadiene polymer resins); Kuraray's "SEPTON HG252" (hydroxyl-modified polystyrene resin); Asahi Kasei's "Tuftec N503M" (carboxyl-modified polystyrene resin); and Asahi Kasei's "Tuftec..." N501 (modified polystyrene resin with amino groups); Asahi Kasei Corporation's "Tuftec M1913" (modified polystyrene resin with anhydride groups); Kuraray Corporation's "SEPTON S8104" (unmodified polystyrene resin); Kraton Corporation's "FG1924" (styrene-ethylene / butene-styrene block copolymer); "EF-40" (CRAY VALLEY Corporation), etc.

[0231] Examples of polyolefin resins include low-density polyethylene, ultra-low-density polyethylene, high-density polyethylene, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, ethylene-methyl acrylate copolymer, and other ethylene-based copolymers; as well as polyolefin polymers such as polypropylene and ethylene-propylene block copolymers.

[0232] Examples of polybutadiene resins include resins containing a hydrogenated polybutadiene backbone, polybutadiene resins containing hydroxyl groups, polybutadiene resins containing phenolic hydroxyl groups, polybutadiene resins containing carboxyl groups, polybutadiene resins containing anhydride groups, polybutadiene resins containing epoxy groups, polybutadiene resins containing isocyanate groups, polybutadiene resins containing urethane groups, and polyphenylene ether-polybutadiene resins.

[0233] Specific examples of polyamide-imide resins include "VYLOMAX HR11NN" and "VYLOMAX HR16NN" manufactured by Toyobo Co., Ltd. Other specific examples of polyamide-imide resins include modified polyamide-imides such as "KS9100" and "KS9300" (polyamide-imide containing a polysiloxane backbone) manufactured by Hitachi Chemical Co., Ltd.

[0234] Specific examples of polyethersulfone resins include "PES5003P" manufactured by Sumitomo Chemical Co., Ltd.

[0235] Specific examples of polysulfone resins include polysulfones such as "P1700" and "P3500" manufactured by Solvay Performance Polymers.

[0236] Polyphenylene ether resin can be, for example, a copolymer of polyphenylene ether and polybutadiene.

[0237] Specific examples of polyetherimide resins include "Ultem" manufactured by GE.

[0238] Examples of polycarbonate resins include hydroxyl-containing polycarbonate resins, phenolic hydroxyl-containing polycarbonate resins, carboxyl-containing polycarbonate resins, anhydride-containing polycarbonate resins, isocyanate-containing polycarbonate resins, and urethane-containing polycarbonate resins. Specific examples of polycarbonate resins include "FPC0220" manufactured by Mitsubishi Gas Chemical Co., Ltd., "T6002" and "T6001" (polycarbonate diol) manufactured by Asahi Kasei Corporation, and "C-1090," "C-2090," and "C-3090" (polycarbonate diol) manufactured by Kuraray Co., Ltd.

[0239] Specific examples of polyetheretherketone resins include "Sumiploy K" manufactured by Sumitomo Chemical Co., Ltd.

[0240] Examples of polyester resins include polyethylene terephthalate resin, polyethylene naphthalate resin, polybutylene terephthalate resin, polybutylene naphthalate resin, polypropylene terephthalate resin, polypropylene naphthalate resin, and polycyclohexanedimethyl terephthalate resin.

[0241] The amount of (F) polymeric resin relative to 100% by mass of the non-volatile components in the resin composition is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, even more preferably 0.2% by mass or more, preferably 10% by mass or less, more preferably 5% by mass or less, and even more preferably 1% by mass or less.

[0242] The amount of polymeric resin (F) relative to 100% by mass of the resin component in the resin composition 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, preferably 10% by mass or less, preferably 5% by mass or less, and more preferably 2% by mass or less.

[0243] <(G) Organic filler materials> The resin composition according to this embodiment may include (G) organic filler material as an optional component. The (G) organic filler material, as component (G), does not contain substances belonging to components (A) to (F) above. The (G) organic filler material is generally incompatible with curable resins such as (A) epoxy resin and (B) maleimide resin and is contained in the resin composition in a particulate state, and is contained in the cured product in a form that maintains this particulate state. One type of (G) organic filler material may be used alone, or two or more may be used in combination.

[0244] As the (G) organic filler material, particles of organic material can be used. The organic material contained in the (G) organic filler material is preferably a rubber component. Examples of rubber components include: silicone elastomers such as polydimethylsiloxane; olefin thermoplastic elastomers such as polybutadiene, polyisoprene, polychloroprene, ethylene-vinyl acetate copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-isobutylene copolymer, acrylonitrile-butadiene copolymer, isoprene-isobutylene copolymer, isobutylene-butadiene copolymer, ethylene-propylene-diene terpolymer, and ethylene-propylene-butene terpolymer; and acrylic thermoplastic elastomers such as poly(meth)acrylate, poly(meth)acrylate, poly(meth)acrylate, poly(cyclohexyl methacrylate), and poly(octyl methacrylate). Furthermore, silicone rubbers such as polysiloxane rubber can also be mixed into the rubber component. The glass transition temperature of the rubber component contained in the rubber particles can be, for example, below 0°C, preferably below -10°C, more preferably below -20°C, and even more preferably below -30°C.

[0245] (G) Organic filler materials can also be core-shell type rubber particles formed by graft copolymerization of core particles containing the rubber components listed above and a shell composed of monomer components that can copolymerize with the rubber components contained in the core particles. The term "core-shell type" here does not necessarily refer only to those in which the core particles and the shell can be clearly distinguished, but also includes those in which the boundary between the core particles and the shell is not clear, and the core particles may not be completely covered by the shell.

[0246] Specific examples of (G) organic filler materials include: Samsung SDI's "CHT"; TechnoUMG's "B602"; Dow's "PARALOID EXL-2602", "PARALOID EXL-2603", "PARALOID EXL-2655", "PARALOID EXL-2311", "PARALOID EXL-2313", "PARALOID EXL-2315", "PARALOID KM-330", "PARALOID KM-336P", "PARALOID KCZ-201"; Mitsubishi Rayon's "METABLEN C-223A", "METABLEN E-901", "METABLEN S-2001", "METABLEN W-450A", "METABLEN SRK-200"; and Kaneka's "Kane Ace M-511", "Kane Ace M-600", "Kane Ace M-600", "Kane Ace M-511", "Kane Ace M-600", "Kane Ace M-223A", "METABLEN E-901", "METABLEN S-2001", "METABLEN W-450A", "METABLEN SRK-200"; and Kaneka's "Kane Ace M-511", "Kane Ace M-600", "Kane Ace M-223A", "METABLEN E-901", "METABLEN S-2001", "METABLEN W-450A", "METABLEN SRK-200". "AceM-400", "Kane Ace M-580", "Kane Ace MR-01", "STAPHYLOID AC3355", "STAPHYLOID AC3816", "STAPHYLOID AC3816N", "STAPHYLOID AC3832", "STAPHYLOID AC4030", "STAPHYLOID AC3364" manufactured by AICA Industries, etc.

[0247] The amount of (G) organic filler material relative to 100% by mass of the non-volatile components of the resin composition is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, even more preferably 0.5% by mass or more, preferably 10% by mass or less, more preferably 5% by mass or less, and even more preferably 2% by mass or less.

[0248] The amount of organic filler material (G) relative to 100% by mass of the resin component in the resin composition is preferably 0.1% by mass or more, more preferably 1% by mass or more, even more preferably 2% by mass or more, preferably 20% by mass or less, preferably 15% by mass or less, and even more preferably 10% by mass or less.

[0249] <(H) Curing Accelerator> The resin composition described in this embodiment may include (H) a curing accelerator as an optional component. The (H) curing accelerator, as component (H), does not contain substances belonging to components (A) to (G) described above. The (H) curing accelerator can act as a catalyst on the reaction of curable resins such as (A) epoxy resin and (B) maleimide resin to promote the curing of the resin composition.

[0250] Examples of (H) curing accelerators 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. A single (H) curing accelerator can be used alone, or two or more can be used in combination.

[0251] Examples of phosphorus-based curing accelerators include: tetrabutylphosphonium bromide, tetrabutylphosphonium chloride, tetrabutylphosphonium acetate, tetrabutylphosphonium decanoate, tetrabutylphosphonium laurate, bis(tetrabutylphosphonium)pyromellitic phthalate, tetrabutylphosphonium hexahydrophthalate, tetrabutylphosphonium 2,6-bis[(2-hydroxy-5-methylphenyl)methyl]-4-methylphenolate, di-tert-butylmethylphosphonium tetraphenylborate, and other aliphatic phosphonium salts; methyltriphenylphosphonium bromide, ethyltriphenylphosphonium bromide, propyltriphenylphosphonium bromide, butyltriphenylphosphonium bromide, benzyltriphenylphosphonium chloride, tetraphenylphosphonium bromide, and p-methylphosphonium bromide. Aromatic phosphonium salts including phenyltriphenylphosphonium tetratolylborate, tetraphenylphosphonium tetraphenylborate, tetraphenylphosphonium tetratolylborate, triphenylethylphosphonium tetraphenylborate, tri(3-methylphenyl)ethylphosphonium tetraphenylborate, tri(2-methoxyphenyl)ethylphosphonium tetraphenylborate, (4-methylphenyl)triphenylphosphonium thiocyanate, tetraphenylphosphonium thiocyanate, and butyltriphenylphosphonium thiocyanate; aromatic phosphine-borane complexes such as triphenylphosphine-triphenylborane; aromatic phosphine-benzoquinone addition reactants such as triphenylphosphine-p-benzoquinone addition reactants; tributylphosphine, tri-tert-butylphosphine, trioctylphosphine, and di-tert-butylphosphine. Butyl(2-butenyl)phosphine, di-tert-butyl(3-methyl-2-butenyl)phosphine, tricyclohexylphosphine, and other aliphatic phosphines; dibutylphenylphosphine, di-tert-butylphenylphosphine, methyldiphenylphosphine, ethyldiphenylphosphine, butyldiphenylphosphine, diphenylcyclohexylphosphine, triphenylphosphine, tri-o-tolylphosphine, tri-m-tolylphosphine, tri-p-tolylphosphine, tri(4-ethylphenyl)phosphine, tri(4-propylphenyl)phosphine, tri(4-isopropylphenyl)phosphine, tri(4-butylphenyl)phosphine, tri(4-tert-butylphenyl)phosphine, tri(2,4-dimethylphenyl)phosphine, tri(2,5-dimethylphenyl)phosphine, tri(2,6- Aromatic phosphines include dimethylphenylphosphine, 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.

[0252] Examples of urea-based curing accelerators 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 include 1-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)[toluenebisdimethylurea], etc.

[0253] Examples of guanidine-based curing accelerators include dicyandiamide, 1-methylguanidine, 1-ethylguanidine, 1-cyclohexylguanidine, 1-phenylguanidine, 1-(o-tolyl)guanidine, dimethylguanidine, diphenylguanidine, trimethylguanidine, tetramethylguanidine, pentamethylguanidine, 1,5,7-triazabicyclo[4.4.0]dec-5-ene, 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene, 1-methylbiguanidine, 1-ethylbiguanidine, 1-n-butylbiguanidine, 1-n-octadecylbiguanidine, 1,1-dimethylbiguanidine, 1,1-diethylbiguanidine, 1-cyclohexylbiguanidine, 1-allylbiguanidine, 1-phenylbiguanidine, and 1-(o-tolyl)biguanidine.

[0254] Examples of imidazole-based curing accelerators include: 2-methylimidazolium, 2-undecylimidazolium, 2-heptadecylimidazolium, 1,2-dimethylimidazolium, 2-ethyl-4-methylimidazolium, 1,2-dimethylimidazolium, 2-ethyl-4-methylimidazolium, 2-phenylimidazolium, 2-phenyl-4-methylimidazolium, 1-benzyl-2-methylimidazolium, 1-benzyl-2-phenylimidazolium, 1-cyanoethyl-2-methylimidazolium, 1-cyanoethyl-2-undecylimidazolium, 1-cyanoethyl-2-ethyl-4-methylimidazolium, 1-cyanoethyl-2-phenylimidazolium, 1-cyanoethyl-2-undecylimidazolium trimellitate, 1-cyanoethyl-2-phenylimidazolium trimellitate, and 2,4-diamino-6-[2'-methylimidazolyl-(1')] -Ethyl-triazine, 2,4-diamino-6-[2'-undecylimidazolyl-(1')]-ethyl-triazine, 2,4-diamino-6-[2'-ethyl-4'-methylimidazolyl-(1')]-ethyl-triazine, 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-triazine isocyanuric acid adduct, 2-phenylimidazolyl isocyanuric acid adduct, 2-phenyl-4,5-dihydroxymethylimidazolium, 2-phenyl-4-methyl-5-hydroxymethylimidazolium, 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. Commercially available imidazole-based curing accelerators include, for example, those manufactured by Shikoku Chemical Industry Co., Ltd. such as "1B2PZ", "2E4MZ", "2MZA-PW", "2MZ-OK", "2MA-OK", "2MA-OK-PW", "2PHZ", "2PHZ-PW", "Cl1Z", "Cl1Z-CN", "Cl1Z-CNS", and "C11Z-A"; and "P200-H50" manufactured by Mitsubishi Chemical Co., Ltd.

[0255] Examples of organometallic 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 organocobalt complexes such as cobalt(II) and cobalt(III) acetylacetone, organocopper complexes such as copper(II) acetylacetone, organozinc complexes such as zinc(II) acetylacetone, organoiron complexes such as iron(III) acetylacetone, organonickel complexes such as nickel(II) acetylacetone, and organomanganese complexes such as manganese(II) acetylacetone. Examples of organometallic salts include zinc octoate, tin octoate, zinc naphthenate, cobalt naphthenate, tin stearate, and zinc stearate.

[0256] Examples of amine-based curing accelerators include trialkylamines such as triethylamine and tributylamine; 4-dimethylaminopyridine, benzyldimethylamine, 2,4,6-tris(dimethylaminomethyl)phenol, and 1,8-diazabicyclo(5,4,0)-undecene. Commercially available products can also be used as amine-based curing accelerators, such as "MY-25" manufactured by Ajinomoto Fine Technology Co., Ltd.

[0257] The amount of (H) curing accelerator relative to 100% by mass of the non-volatile components of the resin composition is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, even more preferably 0.2% by mass or more, preferably 5% by mass or less, more preferably 2% by mass or less, and even more preferably 1% by mass or less.

[0258] The amount of (H) curing accelerator relative to 100% by mass of the resin component in the resin composition is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, even more preferably 1% by mass or more, preferably 10% by mass or less, more preferably 6% by mass or less, and even more preferably 3% by mass or less.

[0259] <(I) Any additives> The resin composition according to this embodiment may further include (I) any additive as an arbitrary component. The (I) any additive as component (I) does not contain substances belonging to components (A) to (H) above. Examples of the (I) any additive include: organometallic compounds such as organocopper compounds, organozinc compounds, and organocobalt compounds; colorants such as phthalocyanine blue, phthalocyanine green, iodine green, diazo yellow, crystal violet, titanium dioxide, and carbon black; polymerization inhibitors such as hydroquinone, catechol, pyrogallol, and phenothiazine; leveling agents such as organosilicon-based leveling agents and acrylic polymer-based leveling agents; thickeners such as bentonite and montmorillonite; defoamers such as organosilicon-based defoamers, acrylic defoamers, fluorine-based defoamers, and vinyl resin-based defoamers; ultraviolet absorbers such as benzotriazole-based ultraviolet absorbers; and adhesion improvers such as ureasilane. Triazole-based binding agents, tetraazole-based binding agents, triazine-based binding agents, and other binding agents; hindered phenolic antioxidants and other antioxidants; zirconia derivatives and other fluorescent whitening agents; fluorinated surfactants, organosilicon surfactants and other surfactants; phosphate ester dispersants, polyoxyethylene dispersants, acetylene dispersants, organosilicon dispersants, anionic dispersants, cationic dispersants and other dispersants; borate ester stabilizers, titanate stabilizers, aluminate stabilizers, zirconate stabilizers, isocyanate stabilizers, carboxylic acid stabilizers, carboxylic anhydride stabilizers and other stabilizers, etc. (I) Any additive may be used alone or in combination of two or more.

[0260] In the resin composition according to this embodiment, as an optional additive (I), any cyclic phosphazene compound other than the cyclic phosphazene compound described in (D) above may be included. Examples of optional cyclic phosphazene compounds include cyclic phosphazene compounds having structures other than those shown in formula (1). However, the resin composition according to this embodiment preferably does not contain the aforementioned optional cyclic phosphazene compound. In particular, when the cyclic phosphazene compound in (D) is a particle with an average particle size of 0.8 μm or more, the resin composition according to this embodiment preferably does not contain the optional cyclic phosphazene compound.

[0261] Furthermore, the resin composition involved in this embodiment may or may not contain phosphorus-based flame retardants other than (D) cyclic phosphazene compounds. The term "phosphorus-based flame retardant" refers to a flame retardant containing phosphorus atoms.

[0262] It should be noted that the resin composition involved in this embodiment may or may not contain a poly(aryl ether) polymer containing the following monomer units: pyrimidine, pyrazine, or pyridazine. That is, compositions containing poly(aryl ether) polymers containing the following monomer units, which are pyrimidine, pyrazine, or pyridazine, can be excluded from the resin composition involved in this embodiment.

[0263] <(J) Solvent> The resin composition according to this embodiment may be combined with non-volatile components such as components (A) to (I) above to further include solvent (J) as a volatile component. Organic solvents are typically used as solvent (J). Examples of organic solvents include: ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; ester solvents such as methyl acetate, ethyl acetate, butyl acetate, isobutyl acetate, isoamyl acetate, methyl propionate, ethyl propionate, and γ-butyrolactone; ether solvents such as tetrahydropyran, tetrahydrofuran, 1,4-dioxane, diethyl ether, diisopropyl ether, dibutyl ether, diphenyl ether, and anisole; alcohol solvents such as methanol, ethanol, propanol, butanol, and ethylene glycol; and 2-ethoxyethyl acetate, propylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, and carbitol acetate. Ether ester solvents such as acetate, γ-butyrolactone, and methyl methoxypropionate; ester alcohol solvents such as methyl lactate, ethyl lactate, and methyl 2-hydroxyisobutyrate; ether alcohol solvents such as 2-methoxypropanol, 2-methoxyethanol, 2-ethoxyethanol, propylene glycol monomethyl ether, and diethylene glycol monobutyl ether (butyl carbitol); amide solvents such as N,N-dimethylformamide, N,N-dimethylacetamide, and N-methyl-2-pyrrolidone; sulfoxide solvents such as dimethyl sulfoxide; nitrile solvents such as acetonitrile and propionitrile; aliphatic hydrocarbon solvents such as hexane, cyclopentane, cyclohexane, and methylcyclohexane; and aromatic hydrocarbon solvents such as benzene, toluene, xylene, ethylbenzene, and trimethylbenzene.

[0264] Solvent (J) can be used alone or in combination of two or more. Preferably, solvent (J) includes a ketone solvent. Using a ketone solvent can particularly effectively improve the stability of the varnish. The amount of ketone solvent relative to 100% by mass of the total amount of solvent (J) is preferably 20% by mass or more, more preferably 40% by mass or more, further preferably 60% by mass or more, preferably 95% by mass or less, more preferably 90% by mass or less, and further preferably 85% by mass or less. Especially when the resin composition is a resin varnish, the amount of ketone solvent contained in the resin varnish is preferably within the above-mentioned range.

[0265] (J) The solvent is preferably a high-boiling-point solvent having a boiling point of 100°C or higher. Examples of preferred high-boiling-point solvents include: cyclohexanone (boiling point 155°C), methylcyclohexane (boiling point: 101°C), ethylcyclohexane (boiling point: 130–132°C), tetrahydronaphthalene (boiling point: 206–208°C), decahydronaphthalene (boiling point: 185–195°C), toluene (boiling point 111°C), methyl n-pentyl ketone (boiling point 151°C), 1-methoxy-2-propanol (boiling point 120°C), and 2-methoxypropanol (boiling point 130°C). Using a high-boiling-point solvent can particularly effectively improve the stability of the varnish. The amount of high-boiling-point solvent is preferably 10% by mass or more, more preferably 20% by mass or more, further preferably 30% by mass or more, preferably 60% by mass or less, more preferably 50% by mass or less, and further preferably 40% by mass or less, relative to 100% by mass of the total amount of (J) solvent. In particular, when the resin composition is a resin varnish, the amount of high-boiling-point solvent contained in the resin varnish is preferably within the above-mentioned range.

[0266] The solvent (J) preferably includes a (J-1) non-aromatic high-boiling solvent. A (J-1) non-aromatic high-boiling solvent refers to a high-boiling solvent that does not contain an aromatic ring in its molecule. Therefore, a (J-1) non-aromatic high-boiling solvent refers to a solvent that does not contain an aromatic ring in its molecule and has a boiling point of 100°C or higher. Examples of (J-1) non-aromatic high-boiling solvents include, for example, cyclohexanone, ethylcyclohexane, decahydronaphthalene, methylpentyl ketone, 1-methoxy-2-propanol, and 2-methoxypropanol. From the viewpoint of film flexibility, the amount of the non-aromatic high-boiling-point solvent (J-1) relative to 100% by mass of the total amount of solvent (J-1) is preferably 1% by mass or more, more preferably 2% by mass or more, further preferably 5% by mass or more, further preferably 10% by mass or more, particularly preferably 13.3% by mass or more or 14% by mass or more. From the viewpoint of varnish stability, it is preferably 40% by mass or less, more preferably 30% by mass or less, further preferably 20% by mass or less, further preferably 19% by mass or less, and further preferably 18% by mass or less. The term "film flexibility" refers to the flexibility of the resin composition layer unless otherwise specified. In addition, from the viewpoint of 100% by mass of the total amount of the resin composition, the amount of the non-aromatic high-boiling-point solvent (J-1) is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, further preferably 1% by mass or more, particularly preferably 3% by mass or more, preferably 20% by mass or less, more preferably 10% by mass or less, further preferably 5% by mass or less, further preferably 4.8% by mass or less, and further preferably 4.7% by mass or less. In particular, when the resin composition is a resin varnish, the amount of high-boiling-point solvent contained in the resin varnish is preferably within the above-mentioned range.

[0267] Specifically, the mass ratio of (J-1) non-aromatic high-boiling solvent to (D) cyclic phosphazene compound ((J-1) non-aromatic high-boiling solvent / (D) cyclic phosphazene compound) is preferably 1.0 or more, more preferably 1.5 or more, further preferably 2.0 or more, more preferably 3.0 or more, particularly preferably 4.5 or more, preferably 15 or less, more preferably 10 or less, and further preferably 8.0 or less. When the mass ratio ((J-1) non-aromatic high-boiling solvent / (D) cyclic phosphazene compound) is within the above range, the stability of the varnish can be improved particularly effectively.

[0268] In one example, when solvent (J) contains cyclohexanone, from the viewpoint of film flexibility, the amount of cyclohexanone is preferably 1% by mass or more, more preferably 2% by mass or more, further preferably 5% by mass or more, and particularly preferably 10% by mass or more, relative to 100% by mass of the total amount of solvent (J). From the viewpoint of varnish stability, it is preferably 40% by mass or less, more preferably 30% by mass or less, and further preferably 20% by mass or less. Furthermore, from the viewpoint of 100% by mass of the total amount of the resin composition, the amount of cyclohexanone is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, further preferably 1% by mass or more, particularly preferably 3% by mass or more, preferably 20% by mass or less, more preferably 10% by mass or less, and further preferably 5% by mass or less. Moreover, the mass ratio of cyclohexanone to (D) cyclic phosphazene compound (cyclohexanone / (D) cyclic phosphazene compound) is preferably 1.0 or more, more preferably 1.5 or more, further preferably 2.0 or more, particularly preferably 3.0 or more, preferably 15 or less, more preferably 10 or less, and further preferably 6.0 or less.

[0269] In one example, when solvent (J) contains toluene, from the viewpoint of resin compatibility and varnish stability, the amount of toluene relative to 100% by mass of the total amount of solvent (J) is preferably 1% by mass or more, more preferably 2% by mass or more, further preferably 5% by mass or more, particularly preferably 10% by mass or more, preferably 40% by mass or less, more preferably 30% by mass or less, and further preferably 20% by mass or less. Furthermore, relative to 100% by mass of the total amount of the resin composition, the amount of toluene is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, further preferably 1% by mass or more, particularly preferably 3% by mass or more, preferably 20% by mass or less, more preferably 10% by mass or less, and further preferably 5% by mass or less. Moreover, the mass ratio of toluene to (D) cyclic phosphazene compound (toluene / (D) cyclic phosphazene compound) is preferably 1.0 or more, more preferably 1.5 or more, further preferably 2.0 or more, particularly preferably 3.0 or more, preferably 15 or less, more preferably 10 or less, and further preferably 6.0 or less.

[0270] When the resin composition involved in this embodiment is a resin varnish, the amount of solvent (J) relative to 100% by mass of the total amount of the resin varnish is preferably 5% by mass or more, more preferably 10% by mass or more, further preferably 20% by mass or more, preferably 60% by mass or less, more preferably 50% by mass or less, further preferably 40% by mass or less, and particularly preferably 30% by mass or less. Resin varnishes containing amounts of solvent (J) within the aforementioned range exhibit particularly excellent varnish stability.

[0271] On the other hand, in the state where a resin composition layer is formed, the amount of (J) solvent contained in the resin composition layer is generally less than the amount of (J) solvent in the resin varnish. Specifically, the range of the amount of (J) solvent in the resin composition layer relative to 100% by mass of the resin composition can be, for example, less than 50% by mass, less than 40% by mass, less than 30% by mass, less than 20% by mass, less than 15% by mass, or less than 10% by mass. The lower limit can be 0% by mass, but is generally greater than 0% by mass.

[0272] <Method for manufacturing resin composition> The resin composition described in this embodiment can be manufactured, for example, by mixing components that may be included in the resin composition. These components can be mixed in part or all at once, or sequentially. During the mixing of the components, the temperature can be appropriately set, allowing for temporary or continuous heating and / or cooling. Furthermore, stirring or agitation can be performed during the mixing of the components.

[0273] <Properties of Resin Compositions and Their Cured Products> The resin composition according to this embodiment can exhibit excellent varnish stability. Therefore, when the resin composition is a resin varnish, the precipitation of components in the resin varnish due to storage can be suppressed. In one example, when the resin composition is stored in a refrigerated environment (e.g., 4°C) for 3 days, the increase rate of precipitates due to storage is preferably less than 1.5, more preferably less than 1.2. The increase rate of precipitates can be determined by the method described in Test Example 1 of the embodiments described later.

[0274] The resin composition involved in this embodiment preferably has high film flexibility. Therefore, the resin composition layer containing the resin composition involved in this embodiment preferably has high flexibility. In one example, for the resin composition layer containing the resin composition, under the conditions of a load of 2.5 N, a bending angle of 90°, a bending radius of 1.0 mm, and a bending speed of 175 times / minute, a bending resistance of more than 100 flexural cycles can be achieved. The term "flexural resistance" refers to the maximum number of times that the material does not break when repeatedly bent. The specific method for measuring the flexural resistance can be the method described in Test Example 6 of the embodiments described later.

[0275] According to the resin composition of this embodiment, it is preferable to obtain a resin composition layer that has suitable adhesion to the protective film. Therefore, when the protective film is adhered to the resin composition layer containing the resin composition of this embodiment, unintentional peeling of the protective film can be suppressed. More preferably, in the case of intentional peeling of the protective film, the protective film can be peeled off smoothly. In one example, when the resin composition layer containing the resin composition is adhered to the protective film, the peel strength SB, which is the load required to peel the protective film from the resin composition layer, is preferably 0.003 kgf / cm or more, and preferably 0.006 kgf / cm or less. The specific method for measuring the peel strength SB can be the method described in Test Example 7 of the embodiments described later.

[0276] By curing the resin composition according to this embodiment, a cured product of the resin composition can be obtained. Then, using this cured product, a cured layer can be formed. Generally, since heat is applied during the curing of the resin composition, volatile components such as solvents (J) in the resin composition can evaporate due to the heat during curing. Therefore, the cured product obtained by curing the resin composition can contain non-volatile components such as components (A) to (I) or their reaction products. The cured layer can be used, for example, as an insulating layer for a circuit board.

[0277] The cured resin composition according to this embodiment can have excellent dielectric properties, specifically, it can have a low dielectric loss tangent Df. In one example, the dielectric loss tangent Df of the cured product is preferably 0.0040 or less, more preferably 0.0039 or less, even more preferably 0.0038 or less, and may also be 0.0030 or less. The lower limit of the dielectric loss tangent Df is not particularly limited, for example, it can be 0.0010 or more.

[0278] The dielectric loss tangent Df of the cured material described above can be measured using the resonant cavity perturbation method under the conditions of a measurement frequency of 5.8 GHz and a measurement temperature of 23 °C. If the sample is a resin composition before curing, the resin composition can be cured at 190 °C for 90 minutes to obtain a cured material, and the dielectric loss tangent Df of the cured material can be measured. The specific measurement method can be the method described in Test Example 2 of the following embodiments.

[0279] The cured resin composition according to this embodiment can exhibit high insulation reliability. Specifically, after a storage test was conducted in which the cured resin composition was stored at a temperature of 130°C and a humidity of 85% RH with a voltage of 3.3V applied for 300 hours, the cured product exhibited a high insulation resistance value. For example, when the insulation resistance value of the cured product was measured using the method described in Test Example 3 of the following embodiments, it is preferable to have a value of 1.0 × 10⁻⁶. 8 An insulation resistance value of Ω or higher. If the sample is a resin composition before curing, the resin composition can be cured at 200°C for 90 minutes to obtain a cured product, and the insulation reliability of the cured product can be evaluated.

[0280] The cured resin composition involved in this embodiment typically exhibits excellent heat resistance, specifically, a high glass transition temperature (Tg). In one example, the glass transition temperature (Tg) of the cured product is preferably 150°C or higher. Upper limits may be, for example, 300°C or lower, 250°C or lower, 200°C or lower, etc.

[0281] The glass transition temperature of the cured product described above can be determined by thermomechanical analysis using the tensile loading method under the conditions of a load of 1g and a heating rate of 5°C / min. If the sample is a resin composition before curing, the resin composition can be cured at 190°C for 90 minutes to obtain a cured product, and the glass transition temperature Tg of the cured product can be measured. The specific measurement method can be the method described in Test Example 2 of the following examples.

[0282] The cured resin composition according to this embodiment typically has a small surface roughness after roughening treatment. In one example, when the cured material was subjected to a decontamination treatment by the method of Test Example 4 of the following embodiments, the arithmetic mean roughness Ra of the cured material surface is preferably 300 nm or less, more preferably 200 nm or less, and even more preferably 100 nm or less. The lower limit may be, for example, 10 nm or more, 20 nm or more, 30 nm or more, etc. The arithmetic mean roughness Ra can be measured by the method described in Test Example 4 of the following embodiments.

[0283] The cured resin composition involved in this embodiment generally exhibits excellent adhesion to the conductor layer formed on the cured material. For example, when a cured material layer is formed and a conductor layer is formed on the cured material layer by plating, the adhesion strength between the cured material layer and the conductor layer can be improved. The adhesion strength can be evaluated based on the magnitude of the force required to peel the conductor layer from the cured material layer (plating peel strength). As a specific example, when the plating peel strength between the insulating layer and the conductor layer corresponding to the cured material layer is measured by the method of Test Example 5 of the embodiment described later, the plating peel strength is preferably 0.4 kgf / cm or more. The plating peel strength can be measured by the method described in Test Example 5 of the embodiment described later.

[0284] The resin compositions and cured products involved in this embodiment are not particularly limited, but they are generally not fibrous. That is, those with fibrous shapes can be excluded from the resin compositions and cured products involved in this embodiment.

[0285] <Uses of Resin Compositions> The resin composition described in this embodiment can be used for forming insulating layers, and is particularly preferred for forming insulating layers on circuit boards. Additionally, the resin composition can be used for manufacturing resin sheets. Typically, these resin sheets are used to form insulating layers. Furthermore, the resin composition can also be used for other applications, such as solder resist, underfill material, chip bonding material, via-filling resin, sealing resin, and component embedding resin. It should be noted that the resin composition described in this embodiment is not particularly limited, but it is generally not used for fiber formation. That is, the application of fibers can be excluded from the uses of the resin composition described in this embodiment.

[0286] <Resin Sheets> One embodiment of the present invention relates to a resin sheet having a support and a resin composition layer formed on the support. The resin composition layer comprises the above-described resin composition, preferably only the above-described resin composition.

[0287] From the viewpoint of thinness, the thickness of the resin composition layer in the resin sheet is preferably 200 μm or less, more preferably 150 μm or less, and even more preferably 100 μm or less. The lower limit of the thickness of the resin composition layer can be, for example, 1 μm or more, 3 μm or more, 5 μm or more, etc.

[0288] Examples of supports include films made of plastic materials, metal foils, and release paper, with films made of plastic materials and metal foils being preferred.

[0289] When a plastic material is used as the support for a film, examples of plastic materials include polyesters such as polyethylene terephthalate (hereinafter sometimes abbreviated as "PET") and polyethylene naphthalate (hereinafter sometimes abbreviated as "PEN"); acrylics such as polycarbonate (hereinafter sometimes abbreviated as "PC") and polymethyl methacrylate (PMMA); cyclic polyolefins; triacetyl cellulose (TAC); polyether sulfide (PES); polyether ketone; and polyimide. Among these, polyethylene terephthalate and polyethylene naphthalate are preferred, and inexpensive polyethylene terephthalate is particularly preferred.

[0290] When metal foil is used as a support, examples of metal foil include copper foil and aluminum foil. Copper foil is preferred. As copper foil, foil containing a single metal such as copper can be used, or foil containing an alloy of copper and other metals (such as tin, chromium, silver, magnesium, nickel, zirconium, silicon, titanium, etc.) can be used.

[0291] For the support, surface treatments such as matte finish, corona treatment, and antistatic treatment can be applied to the surface that bonds with the resin composition layer.

[0292] As a support, a support with a release layer can be used on the surface that bonds to the resin composition layer. Examples of release agents used in the release layer of the support with a release layer include, for example, one or more release agents selected from alkyd-based, polyolefin-based, polyurethane-based, and silicone-based release agents. Commercially available products can be used as the support with the release layer, such as, for example, PET films having a release layer primarily composed of silicone-based or alkyd-based release agents, such as Lintec's "PET501010", "SK-1", "AL-5", and "AL-7"; Toray's "Lumirror T60"; Teijin's "Purex"; and Unitika's "Unipeel".

[0293] The thickness of the support is not particularly limited, but is preferably 1 μm or more, more preferably 5 μm or more, even more preferably 10 μm or more, preferably 75 μm or less, more preferably 60 μm or less, and even more preferably 50 μm or less. When using a support with a release layer, it is preferable that the overall thickness of the support with the release layer is within the above-mentioned range.

[0294] The resin sheet can have any components as needed. For example, the resin sheet can have a protective film that protects the resin composition layer. The protective film is usually applied to the side of the resin composition layer that is not in contact with the support (i.e., the side opposite to the support). The thickness of the protective film is not particularly limited, and can be, for example, from 1 μm to 40 μm. With the protective film, it is possible to suppress the adhesion of debris and the generation of damage on the surface of the resin composition layer.

[0295] Resin sheets can be manufactured, for example, by forming a resin composition layer on a support. Specifically, a resin varnish, which is the resin composition, can be applied to a support and then dried to form a resin composition layer, thereby manufacturing a resin sheet.

[0296] The coating of the resin composition can be performed using a coating apparatus such as a die coater. Drying can be carried out by methods such as heating or hot air blowing. Drying conditions are not particularly limited, but drying is typically performed with a solvent content in the resin composition layer of 10% by mass or less, preferably 5% by mass or less. Depending on the boiling point of the solvent, for example, when using a resin composition containing 30% to 60% by mass of solvent, a resin composition layer can be formed by drying at 50°C to 150°C for 3 to 10 minutes.

[0297] The manufactured resin sheets can be wound into rolls for storage. When the resin sheet has a protective film, it can usually be used by peeling off the protective film.

[0298] <Circuit substrate> One embodiment of the present invention relates to a circuit board comprising a cured product of the aforementioned resin composition. Typically, the circuit board has a cured product layer comprising a cured product of the resin composition. The cured product layer may comprise only a cured product of the resin composition. The cured product layer may be used, for example, as an insulating layer such as an interlayer insulating layer. The thickness of the cured product layer is not particularly limited, and may, for example, be within the same range as the thickness of the resin composition layer on the resin sheet. Furthermore, the cured product layer may generally have the same properties as the cured product of the aforementioned resin composition.

[0299] Preferably, the circuit board has an inner substrate on which the aforementioned cured layer serves as an insulating layer. Additionally, the circuit board may include a conductor layer. For example, a conductor layer may be provided on the insulating layer. Hereinafter, examples of preferred methods for manufacturing the circuit board will be described.

[0300] The preferred example involves a method for manufacturing a circuit board that includes: The process of forming a resin composition layer on the inner substrate (I), and Step (II) for curing the resin composition layer.

[0301] An "inner layer substrate" is a component that forms the substrate of a circuit board, and examples include glass epoxy boards, metal substrates, polyester substrates, polyimide substrates, BT resin substrates, and thermosetting polyphenylene ether substrates. Furthermore, the inner layer substrate may have conductive layers on one or both sides. Additionally, the conductive layers of the inner layer substrate may be patterned. Circuit wiring can be formed using the patterned conductive layers. An inner layer substrate with conductive layers formed on one or both sides of the substrate is sometimes called an "inner layer circuit board." Furthermore, intermediate components to be further formed with insulating layers and / or conductive layers during the manufacture of a circuit board are also included in the term "inner layer substrate." Additionally, inner layer substrates with built-in components can be used.

[0302] From the viewpoint of utilizing the advantage of suppressing the formation of large particles caused by the leaching of components in the resin varnish, it is preferable that the circuit board using the resin composition according to the above embodiments has a small minimum line width and line spacing (L / S) of the circuit wiring. Unless otherwise specified, "line width" (L) refers to the width of the circuit wiring, and "line spacing" (S) refers to the spacing between the wirings. The range of the minimum line width and line spacing (L / S) is preferably 10 μm / 10 μm or less, more preferably 5 μm / 5 μm or less, further preferably 3 μm / 3 μm or less, preferably 0.1 μm / 0.1 μm or more, more preferably 0.5 μm / 0.5 μm or more, and further preferably 1 μm / 1 μm or more. In addition, the wiring pitch is preferably 20 μm or less, more preferably 10 μm or less, further preferably 6 μm or less, preferably 0.2 μm or more, more preferably 1 μm or more, and further preferably 2 μm or more. Line width and line spacing (L / S) and wiring spacing can be uniform or non-uniform throughout the conductor layer.

[0303] The formation of a resin composition layer on the inner substrate can be carried out, for example, by a method that includes a resin composition such as a resin varnish coated on the inner substrate and then dried as needed, but it is preferable to use a resin sheet. The method for forming a resin composition layer using a resin sheet typically includes a step of laminating the resin sheet to the inner substrate. The lamination of the resin sheet to the inner substrate is performed in such a way that the resin composition layer of the resin sheet is bonded to the inner substrate. This lamination can also be performed, for example, by heating and pressing the resin sheet onto the inner substrate from the support side. Examples of components for heating and pressing the resin sheet onto the inner substrate (hereinafter also referred to as "heat-pressing component") include, for example, a heated metal plate (SUS end plate, etc.) or a metal roller (SUS roller, etc.). It should be noted that it is preferable not to directly press the heat-pressing component onto the resin sheet, but rather to press it using an elastic material such as heat-resistant rubber so that the resin sheet fully follows the surface irregularities of the inner substrate.

[0304] The lamination of the inner substrate and the resin sheet can be performed using vacuum lamination. In vacuum lamination, the heating and pressing temperature is preferably in the range of 60°C to 160°C, more preferably in the range of 80°C to 140°C; the heating and pressing pressure is preferably in the range of 0.098 MPa to 1.77 MPa, more preferably in the range of 0.29 MPa to 1.47 MPa; and the heating and pressing time is preferably in the range of 20 seconds to 400 seconds, more preferably in the range of 30 seconds to 300 seconds. Lamination is preferably performed under reduced pressure conditions of 26.7 hPa or less.

[0305] Lamination can be performed using commercially available vacuum laminators. Examples of commercially available vacuum laminators include the vacuum pressure laminator manufactured by Meiki Seisakusho, the vacuum dressing machine manufactured by Nikko-materials, and batch vacuum pressure laminators.

[0306] A method for manufacturing a circuit board may include: after lamination, pressing a heated bonding member under normal pressure (atmospheric pressure), for example from the support side, thereby performing a smoothing treatment on the resin sheet. The pressing conditions for the smoothing treatment can be the same as the conditions for the heated bonding of the lamination described above. The smoothing treatment can be performed using a commercially available laminator. Lamination and smoothing treatment can also be performed continuously using the aforementioned commercially available vacuum laminator.

[0307] The circuit board manufacturing method described in this example includes a step (II) after step (I) in which the resin composition layer is cured. By curing the resin composition layer in step (II), an insulating layer can be formed as a cured product containing the resin composition.

[0308] The curing of the resin composition layer is usually carried out by heat curing. The heat curing conditions of the resin composition layer can also vary depending on the type of resin composition. For example, the curing temperature is preferably 120°C to 240°C, more preferably 150°C to 220°C, and even more preferably 170°C to 210°C. In addition, 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.

[0309] A method for manufacturing a circuit board may include preheating the resin composition layer at a temperature lower than the curing temperature before thermal curing. For example, before thermal curing the resin composition layer, it may typically be preheated at a temperature of 50°C to 150°C, preferably 60°C to 140°C, more preferably 70°C to 130°C, for at least 5 minutes, preferably 5 minutes to 150 minutes, more preferably 15 minutes to 120 minutes, and even more preferably 15 minutes to 100 minutes. Preheating is usually performed after step (I). Furthermore, if a smoothing treatment is performed after the inner layer substrate and the resin sheet are laminated, preheating may typically be performed after the smoothing treatment.

[0310] When using resin sheets, the circuit board manufacturing method may include a step of peeling off the support of the resin sheet after the inner layer substrate and the resin sheet are laminated. The peeling off of the support may be performed between steps (I) and (II), or after step (II). Furthermore, if the circuit board manufacturing method, as described below, includes a step (III) of forming holes in the insulating layer, a step (IV) of roughening the insulating layer, and a step (V) of forming a conductor layer, the peeling off of the support may be performed between steps (II) and (III), between steps (III) and (IV), or between steps (IV) and (V).

[0311] The manufacturing method of the circuit board may include a step (III) after step (II) to form holes such as via holes and through holes in the insulating layer. The method for forming the holes can be selected based on factors such as the composition of the resin composition used in the formation of the insulating layer. For example, holes can be formed by processing methods such as drilling, laser processing, and plasma processing, with laser processing being preferred. For example, holes can be formed by irradiating the insulating layer with a laser after the support is peeled off, or holes can be formed by irradiating the insulating layer with a laser through the support. The size and shape of the holes can be appropriately determined according to the design of the circuit board.

[0312] The method for manufacturing a circuit board may include a step (IV) of roughening the insulating layer. This roughening process roughens the surface of the insulating layer. Furthermore, it removes contaminants (resin residue) from the insulating layer. Therefore, this roughening process is sometimes referred to as a "decontamination process." For example, if a hole is formed in step (III), contaminants may form within the hole; therefore, it is preferable to perform the roughening process (IV) after step (III) to remove the aforementioned contaminants.

[0313] There are no particular limitations on the steps and conditions of the roughening treatment; known steps and conditions commonly used in forming the insulating layer of a circuit board can be adopted. For example, the insulating layer can be roughened by sequentially performing a swelling treatment using a swelling solution, a roughening treatment using an oxidizing agent, and a neutralization treatment using a neutralizing solution.

[0314] Examples of swelling solutions used in the roughening process include alkaline solutions and surfactant solutions, with alkaline solutions being preferred. Sodium hydroxide solution and potassium hydroxide solution are more preferred. Commercially available swelling solutions include, for example, "Swelling Dip Securiganth P" and "Swelling Dip Securiganth SBU" manufactured by Ammet Japan Co., Ltd. Swelling treatment using a swelling solution can be performed, for example, by immersing the insulating layer in a swelling solution at 30°C to 90°C for 1 to 20 minutes. From the viewpoint of suppressing the swelling of the resin in the insulating layer to an appropriate level, it is preferable to immerse the insulating layer in a swelling solution at 40°C to 80°C for 5 to 15 minutes.

[0315] Examples of oxidants used in roughening treatments include alkaline permanganate solutions, such as potassium permanganate or sodium permanganate dissolved in an aqueous solution of sodium hydroxide. Roughening treatment using an oxidant such as an alkaline permanganate solution preferably involves immersing the insulating layer in an oxidant solution heated to 60°C to 100°C for 10 to 30 minutes. Furthermore, the concentration of permanganate in the alkaline permanganate solution is preferably 5% to 10% by mass. Commercially available oxidants include alkaline permanganate solutions such as "Concentrate Compact CP" and "Dosing Solution Securiganth P" manufactured by Ammet Japan Co., Ltd.

[0316] The neutralizing solution used in the roughening process is preferably an acidic aqueous solution. Commercially available examples include, for instance, "Reduction Solution Securiganth P" manufactured by Ammet Japan Co., Ltd. The neutralization process using the neutralizing solution can be performed by immersing the surface that has undergone oxidation treatment with an oxidizing agent in a neutralizing solution at 30°C to 80°C for 5 to 30 minutes. From an operational point of view, it is preferable to immerse the object that has undergone oxidation treatment with an oxidizing agent in a neutralizing solution at 40°C to 70°C for 5 to 20 minutes.

[0317] The method for manufacturing a circuit board may include a step (V) of forming a conductor layer on an insulating layer. In the case where the method for manufacturing a circuit board includes step (III) or (IV), the step (V) of forming the conductor layer is generally preferably performed after steps (III) and (IV).

[0318] The conductor material used in the conductor layer is not particularly limited. In a preferred embodiment, the conductor layer comprises one or more metals selected from gold, platinum, palladium, silver, copper, aluminum, cobalt, chromium, zinc, nickel, titanium, tungsten, iron, tin, and indium. The conductor layer can 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-mentioned metals (e.g., nickel-chromium alloys, copper-nickel alloys, and copper-titanium alloys). From the viewpoints of versatility in conductor layer formation, cost, and ease of pattern formation, a single metal layer of chromium, nickel, titanium, aluminum, zinc, gold, palladium, silver, or copper, or an alloy layer of nickel-chromium alloy, copper-nickel alloy, or copper-titanium alloy, is preferred. More preferably, a single metal layer of chromium, nickel, titanium, aluminum, zinc, gold, palladium, silver, or copper, or an alloy layer of nickel-chromium alloy, is preferred. A single metal layer of copper is even more preferred.

[0319] The conductor layer can have a single-layer structure or a multi-layer structure comprising two or more single-metal layers or alloy layers of different types of metals or alloys. In the case of a multi-layer conductor layer, the layer in contact with the insulating layer is preferably a single-metal layer of chromium, zinc, or titanium, or an alloy layer of nickel-chromium alloy.

[0320] The thickness of the conductor layer varies depending on the design of the circuit board, but is preferably 3μm to 35μm, and more preferably 5μm to 30μm.

[0321] The conductor layer can be formed by plating. For example, a conductor layer with a desired wiring pattern can be formed by plating the surface of the insulating layer using conventional techniques such as semi-additive and fully additive methods. From the viewpoint of ease of manufacturing, the semi-additive method is preferred. An example of forming a conductor layer by the semi-additive method is shown below.

[0322] First, an electroless plating layer (plating seed layer) is formed on the surface of the insulating layer by electroless plating. Next, a mask pattern is formed on the formed electroless plating layer, exposing a portion of the electroless plating layer, corresponding to the desired wiring pattern. After forming an electrolytic plating layer on the exposed electroless plating layer by electrolytic plating, the mask pattern is removed. Then, the unwanted electroless plating layer is removed by etching, thus forming a conductor layer with the desired wiring pattern.

[0323] As another example, the conductor layer can be formed using metal foil. When forming the conductor layer using metal foil, it is preferable to perform step (V) between step (I) and step (II). For example, after step (I), the support is removed, and metal foil is laminated onto the surface of the exposed resin composition layer. The lamination of the resin composition layer and the metal foil can be performed using a vacuum lamination method. The lamination conditions can be the same as those described for step (I). Next, step (II) is performed to form an insulating layer. Then, using the metal foil on the insulating layer, a conductor layer with a desired wiring pattern can be formed using known techniques such as subtractive processing or modified semi-additive processing. Metal foil can be manufactured, for example, by known methods such as electrolysis or rolling. Commercially available metal foils include, for example, HLP foil and JXUT-III foil manufactured by JX Metals Corporation, and 3EC-III foil and TP-III foil manufactured by Mitsui Mining & Metals Corporation.

[0324] When a conductor layer is formed on an insulating layer, the manufacturing method of the circuit board may include annealing after the conductor layer is formed. Annealing can improve the adhesion between the insulating layer and the conductor layer. Annealing can be performed, for example, by heating at 150°C to 210°C for 20 to 180 minutes.

[0325] In the manufacturing method of the circuit board, each of the above-mentioned processes may be performed only once or repeatedly more than twice. For example, processes (I) to (V) can be repeatedly performed to form a circuit board with a multilayer structure, such as a multilayer printed wiring board having multiple insulating layers and conductor layers.

[0326] The method for manufacturing a circuit board can be combined with the aforementioned steps to further include any additional steps. For example, the method may include a step of placing a semiconductor chip in a manner that bonds it to a conductive layer. Specifically, in the case of manufacturing a circuit board for a semiconductor chip package containing a semiconductor chip, the method may include a step of placing the semiconductor chip. The conditions for placing the semiconductor chip can be appropriate conditions that allow for conductive connection between the terminal electrodes of the semiconductor chip and the conductive layer formed on the insulating layer. For example, conditions used in flip-chip mounting can be used. Furthermore, the semiconductor chip can be bonded via an insulating adhesive or by reflow soldering. Furthermore, if necessary, the placed semiconductor chip can be filled with a molding underfill material. Additionally, the method may include, for example, a step of forming a sealing layer, a step of forming a solder resist layer, and a step of cutting the manufactured circuit board into monolithic wafers.

[0327] Examples of circuit boards include printed wiring boards and semiconductor chip packages. Examples of semiconductor chip packages include FC-CSP, MIS-BGA packages, ETS-BGA packages, fan-out type WLP (Wafer Level Package), fan-in type WLP, fan-out type PLP (Panel Level Package), and fan-in type PLP. In these semiconductor chip packages, it is preferable to use a cured product formed by curing the aforementioned resin composition to form the rewiring layer as an insulating layer. However, the circuit board is not limited to those examples here.

[0328] Semiconductor Devices The circuit board described above can be used in the manufacture of semiconductor devices. Semiconductor devices include the circuit board described above. Examples of semiconductor devices include various semiconductor devices used in electrical products (e.g., computers, mobile phones, smartphones, tablets, wearable devices, digital cameras, medical devices, and televisions) and vehicles (e.g., motorcycles, automobiles, trams, ships, and airplanes). Example

[0329] The present invention will be specifically described below with reference to embodiments. However, the present invention is not limited to the embodiments described below. In the following description, "parts" and "%" to indicate quantities refer to "parts by mass" and "% by mass," respectively, unless otherwise specified. In addition, the temperature and pressure conditions are room temperature (23°C) and atmospheric pressure (1 atm) unless otherwise specified. In the following description, unless otherwise specified, Mw / Mn represents weight-average molecular weight / number-average molecular weight.

[0330] <First Dissolution Test and Second Dissolution Test> To investigate the solubility of flame retardants such as (D) cyclic phosphazene compounds used in the examples described below in cyclohexanone, the following first and second dissolution tests were conducted.

[0331] (First dissolution test) Add 0.5g of the flame retardant (component (D) or (D')) used in each example to 10g of cyclohexanone. While heating at a measurement temperature of 25°C, perform ultrasonic treatment for 10 minutes to dissolve the flame retardant. After the added flame retardant is completely dissolved in cyclohexanone, add another 0.5g of flame retardant and repeat the ultrasonic treatment for 10 minutes. Repeat the above addition of flame retardant and ultrasonic treatment until the flame retardant no longer dissolves in cyclohexanone and precipitates are observed. Calculate the cumulative amount added until the flame retardant no longer dissolves in cyclohexanone and precipitates are observed as the dissolved amount of flame retardant.

[0332] (Second Dissolution Test) Except that the measurement temperature was changed to 70°C, the amount of flame retardant dissolved in 10g of cyclohexanone at 70°C was determined by the same method as the first dissolution test described above.

[0333] <Synthesis Example 1. Synthesis of Liquid Epoxy Resin A> 100g of 2,2-bis(4-hydroxy-3-methylphenyl)propane was dissolved in 1050g of epichlorohydrin, and 0.25g of benzyltriethylammonium chloride was added. 90g of a 48% sodium hydroxide aqueous solution was added dropwise over 5 hours at 70°C under reduced pressure. The generated water was removed from the system by azeotropic reaction with the epichlorohydrin, and the distilled epichlorohydrin was returned to the system. After the addition, the reaction continued for 2 hours, and then the generated salt was removed by filtration, followed by washing with water and distillation to remove the epichlorohydrin. The resulting epoxy resin was dissolved in 400g of methyl isobutyl ketone, and 10g of a 10% sodium hydroxide aqueous solution was added at 85°C, allowing the reaction to proceed for 2 hours. After the reaction, the resin was filtered, washed with water, and distilled to remove the methyl isobutyl ketone, yielding 129g of a pale yellow liquid epoxy resin A. This epoxy resin A has the structure shown in formula (a-1) (where n is 0-5), and its epoxy equivalent is 193g / eq.

[0334] [Chemical Formula 21]

[0335] <Synthetic Example 2. Synthesis of Maleimide Resin A> A MEK solution (70% by mass) of maleimide resin A (Mw / Mn = 1.81, u' = 1.47 (mainly 1, 2 or 3)) as shown in the following formula (b-4) was prepared using the method described in Synthesis Example 1 of Japanese Invention Publication No. 2020-500211.

[0336] [Chemical Formula 22]

[0337] <Synthesis Example 3: Synthesis of Maleimide Resin B> (I) Synthesis of intermediate amine compound (c-1) In a flask equipped with a thermometer, cooling tubes, a Dean-Stark trap, and a stirrer, 400 g (3.3 mol) of 2-ethylaniline, 127 g of a compound with a benzyl ether skeleton (NIKANOL L, manufactured by Fudow Co., Ltd.), 193 g of toluene, and 53 g of activated clay were added. The mixture was heated to 120°C while stirring and held for 30 minutes. Then, the temperature was increased to 150°C and held for 3 hours. After this holding period, the temperature was increased to 200°C over 30 minutes and held for 10 hours. After this holding period, the mixture was diluted with 193 g of toluene, and the activated clay was separated by filtration. The solvent and excess 2-ethylaniline were removed from the filtrate by distillation under reduced pressure to obtain the intermediate amine compound (c-1) (amine equivalent 209 g / equivalent).

[0338] (II) Maleimide In a 2L flask equipped with a thermometer, cooling tube, Dean-Stark water separator, and stirrer, 73.2 g (126 mol, 1.3 equivalents) of maleic anhydride and 461 g of toluene were added and stirred at room temperature. Next, a mixed solution of 209 g (1 equivalent) of intermediate amine compound (c-1) and 57.7 g of N,N-dimethylformamide (DMF) was added dropwise over 1 hour, and the reaction was allowed to proceed for 2 hours. Then, 9.72 g of p-toluenesulfonic acid monohydrate was added to the reaction solution, and the solution was heated to 115°C. After cooling and separating the azeotropic water and toluene under reflux, only the toluene was returned to the system for a 5-hour dehydration reaction. After air cooling to room temperature, the resulting brown solution obtained by vacuum concentration was dissolved in 600 g of ethyl acetate, washed three times with 200 g of deionized water, and then washed three times with 150 g of 2% sodium bicarbonate aqueous solution. After adding sodium sulfate and drying, the reactants obtained by vacuum concentration are dried at 80°C for 4 hours to obtain maleimide resin B as shown in formula (b-5). In formula (b-5), n represents an integer greater than or equal to 1. 1 Each of these represents the number of repeating units independently, and Et represents the ethyl group.

[0339] [Chemical Formula 23]

[0340] <Synthesis Example 4: Synthesis of Active Ester Resin B> In a flask equipped with a thermometer, dropping funnel, cooling tube, fractionating tube, and stirrer, 165 g of a dicyclopentadiene and phenol addition polymerization resin (hydroxyl equivalent: 165 g / eq., softening point 85 °C), 134 g (1.0 mol) of o-allylphenol, and 1200 g of toluene were added, and the system was purged with nitrogen under reduced pressure. Next, 203 g (1.0 mol) of isophthaloyl chloride was added, and the system was purged with nitrogen under reduced pressure. Then, 0.6 g of tetrabutylammonium bromide was added, and while purging with nitrogen and maintaining the system temperature below 60 °C, 412 g of a 20% sodium hydroxide aqueous solution was added dropwise over 3 hours. After the addition was complete, the mixture was stirred for 1 hour. After the reaction was complete, the aqueous layer was removed by sedimentation. Water was further added to the resulting toluene layer, and the mixture was stirred for 15 minutes. The aqueous layer was then removed by sedimentation. This process was repeated until the pH of the aqueous layer reached 7. Then, the non-volatile components are adjusted to 70% by mass by heating and drying to obtain the active ester resin B shown in formula (e-2).

[0341] [Chemical Formula 24]

[0342] <Synthesis Example 5: Synthesis of Active Ester Resin C> 320 g (2.0 mol) of 2,7-dihydroxynaphthalene, 184 g (1.7 mol) of benzyl alcohol, and 5.0 g of p-toluenesulfonic acid monohydrate were added to a flask equipped with a thermometer, dropping funnel, cooling tube, fractionating tube, and stirrer. The mixture was stirred while being purged with nitrogen at room temperature. Then, the temperature was raised to 150 °C, and the generated water was distilled off while stirring for 4 hours. After the reaction was complete, 900 g of methyl isobutyl ketone and 5.4 g of 20% sodium hydroxide aqueous solution were added for neutralization. The aqueous layer was then removed by separation, followed by three washes with 280 g of water. Methyl isobutyl ketone was removed under reduced pressure to obtain 460 g of benzyl-modified naphthalene compound (C'). The obtained benzyl-modified naphthalene compound (C') was a black solid with a hydroxyl equivalent of 180 g / eq.

[0343] In a flask equipped with a thermometer, dropping funnel, cooling tube, fractionating tube, and stirrer, 203.0 g of isophthaloyl chloride (2.0 mol of acyl chloride group) and 1400 g of toluene were added, and the system was purged with nitrogen under reduced pressure to dissolve the compounds. Next, 113.9 g (0.67 mol) of o-phenylphenol and 240 g of benzyl-modified naphthalene compound (C') (1.33 mol of phenolic hydroxyl group) were added, and the system was purged with nitrogen under reduced pressure to dissolve the compounds. Then, 0.70 g of tetrabutylammonium bromide was dissolved, and while purging with nitrogen and maintaining the system temperature below 60°C, 400 g of 20% sodium hydroxide aqueous solution was added dropwise over 3 hours. The reaction was then continued under these conditions with stirring for 1 hour.

[0344] After the reaction was completed, the mixture was allowed to stand and separate to remove the aqueous layer. Then, water was added to the toluene layer containing the reactants and stirred for 15 minutes. The mixture was allowed to stand and separate to remove the aqueous layer. This process was repeated until the pH of the aqueous layer reached 7. The water was then removed using a decanter to obtain an active ester resin C in a toluene solution containing 62% by mass of non-volatile components. The structure of the obtained active ester resin C is shown in formula (e-4). The active ester equivalent of the obtained active ester resin C is 238 g / eq.

[0345] [Chemical Formula 25]

[0346] <Synthesis Example 6: Synthesis of Polyimide Resin A> In 400g of N,N-dimethylacetamide (hereinafter sometimes referred to as "DMAc"), a monomer mixture obtained by mixing 46.5g of 2,2-bis[4-(3,4-dicarboxyphenoxy)phenyl]propane dianhydride (hereinafter sometimes referred to as "BPADA"), 50.4g of 4,4'-[1,4-phenylenebis[(1-methylethoxy)-4,1-phenylene]]bisphenylamine (hereinafter sometimes referred to as "BPPAN"), 1.9g of 5-norbornene-2,3-dicarboxylic anhydride, and 40g of toluene was stirred at room temperature and atmospheric pressure for 3 hours to allow it to react. This yielded a polyamic acid solution. The resulting polyamic acid solution was heated and, while maintained at approximately 160°C, condensed water was azeotropically removed with toluene under a nitrogen stream. It was confirmed that "a specified amount of water accumulated in the moisture metering receiver" and "no more water flow was observed." After confirmation, the reaction solution was further heated and stirred at 200°C for 1 hour. Then, cooling is performed. This yields a solution of polyimide resin A (concentration of polyimide resin A: 20% by mass).

[0347] <Synthesis Example 7: Synthesis of Polyimide Resin B> In 400g of DMAc, a monomer mixture consisting of 46.5g of BPADA, 37.8g of BPPAN, 12.8g of dimer diamine (Cargill's "PRIAMINE 1075"), 1.9g of 5-norbornene-2,3-dicarboxylic anhydride, and 40g of toluene was stirred at room temperature and atmospheric pressure for 3 hours to allow it to react. This yielded a polyamic acid solution. Except that the obtained polyamic acid solution was used instead of the polyamic acid solution used in Synthesis Example 6, a solution of polyimide resin B (concentration of polyimide resin B 20% by mass) was obtained by the same method as in Synthesis Example 6.

[0348] <Examples 1-21 and Comparative Examples 1-4> (1) Preparation of resin composition: Weigh each component according to the formulation described in Tables 2 and 3 below, then mix 20 parts of MEK and disperse evenly using a high-speed rotary mixer to obtain a resin varnish as a resin composition. In the formulation described in Tables 2 and 3, the amounts of components (A) to (H) represent the amounts (parts by mass) of non-volatile components, and the amount of component (J) as a solvent represents the amount (parts by mass) of the solvent itself in the total resin varnish. Further details of each component described in Tables 2 and 3 are as follows.

[0349] (A) Epoxy resin: NC3000L: Epoxy equivalent 271g / eq., manufactured by Nippon Kayaku Co., Ltd., biphenyl type epoxy resin. YX4000H: Epoxy equivalent 194 g / eq., manufactured by Mitsubishi Chemical Corporation, bisphenol backbone epoxy resin. HP6000L: Epoxy equivalent 213g / eq., manufactured by DIC, naphthalene-type epoxy resin HP7200L: Epoxy equivalent 246g / eq., manufactured by DIC, DCPD type epoxy resin • ESN-475V: Epoxy equivalent 332 g / eq., manufactured by Nippon Steel Chemical Materials Co., Ltd., naphthol aralkyl type epoxy resin • ESN-4100VEK75: Epoxy equivalent 363 g / eq., manufactured by Nippon Steel Chemical Materials Co., Ltd., naphthol aralkyl type epoxy resin, MEK solution with 75% solids content. WHR-991S: Epoxy equivalent 266 g / eq., manufactured by Nippon Kayaku Co., Ltd., phenol-benzopyrrolidone type epoxy resin. HP4032SS: Epoxy equivalent 144 g / eq., manufactured by DIC, naphthalene-type epoxy resin JER828: Epoxy equivalent 186 g / eq., manufactured by Mitsubishi Chemical Corporation, bisphenol A type epoxy resin. ZX-1059: Epoxy equivalent 165g / eq., manufactured by Nippon Steel Chemical Materials Co., Ltd., bisphenol A type epoxy resin. • Liquid epoxy resin A: Epoxy equivalent 191 g / eq., the liquid epoxy resin A synthesized in Synthesis Example 1.

[0350] (B-1) Aromatic maleimide resin: • Maleimide resin A: maleimide equivalent 428 g / eq., maleimide resin B synthesized in Synthesis Example 2, and MEK solution with 70% solids content. MIR-3000-70MT: A mixed solution of MEK and toluene with a maleimide equivalent of 393 g / eq., manufactured by Nippon Kayaku Co., Ltd., and containing 70% solids. • MIR-5000-60T: Toluene solution with a maleimide equivalent of 266 g / eq., manufactured by Nippon Kayaku Co., Ltd., and a solid content of 60%. • Maleimide Resin B: Maleimide equivalent of 300 g / eq., Maleimide Resin B synthesized in Synthesis Example 3, MEK solution with a solid content of 75%. BMI-70: Maleimide equivalent 221 g / eq., manufactured by KI Chemical Co., Ltd. • BMI-80: Maleimide equivalent 285g / eq., manufactured by KI Chemical Co., Ltd.

[0351] (B-2) Aliphatic maleimide resin: BMI-689: Maleimide equivalent 345 g / eq., manufactured by Desinger Molecules Inc. • BMI-1500: Maleimide equivalent 752 g / eq., manufactured by Desinger Molecules Inc. • BMI-3000: Maleimide equivalent 1500g / eq., manufactured by Desinger Molecules Inc.

[0352] (C) Inorganic filler materials: • SO-C2: Spherical silica with an average particle size of 0.5 μm, manufactured by Yaduma Corporation, and surface-treated with an amine-based silane coupling agent (Shin-Etsu Chemical Co., Ltd.'s "KBM573"). • LHP-208: Hollow silica manufactured by Ube EXSYMO Corporation, with an average particle size of 0.5 μm, a porosity of 50% by volume, and surface-treated with an amine-based silane coupling agent (Shin-Etsu Chemical Industry Co., Ltd.'s "KBM573"). ·MG-005: Hollow silica manufactured by Pacific Cement Corporation, with an average particle size of 1.6 μm, a porosity of 80% by volume, and surface treated with an amine silane coupling agent (Shin-Etsu Chemical Industry Co., Ltd. "KBM573").

[0353] (D) Cyclic phosphazene compounds: FP-72TP: A cyclic phosphazene compound as shown in formula (d-1). It has a melting point above 280°C, a phosphorus content of 14.4%, a nitrogen content of 6.5%, an average particle size of 1 μm, a maximum particle size of 10 μm, and a solubility of 0.00 g in 10 g of cyclohexanone at 25°C as determined in the first dissolution test, and a solubility of 0.00 g in 10 g of cyclohexanone at 70°C as determined in the second dissolution test.

[0354] [Chemical Formula 26]

[0355] FP-72TP pulverized product: a cyclic phosphazene compound with an average particle size of 0.7 μm and a maximum particle size of 5.0 μm.

[0356] (D') Any flame retardant: • HCA-HQ-HST: Flame retardant as shown in formula (d'-2), manufactured by Samkwang Corporation, with a phosphorus content of 10% by mass and an average particle size of 1.5 μm. In the first dissolution test, the solubility in 10 g of cyclohexanone at 25°C was 0.05 g, and in the second dissolution test, the solubility in 10 g of cyclohexanone at 70°C was 0.40 g.

[0357] [Chemical Formula 27]

[0358] •FP-100: Flame retardant, phosphorus content 13.4% by mass, manufactured by Fushimi Pharmaceutical Co., Ltd. The solubility in 10g of cyclohexanone at 25°C, as determined in the first dissolution test, was 0.40g. The solubility in 10g of cyclohexanone at 70°C, as determined in the second dissolution test, was also 0.40g.

[0359] (E) Any curable resin: • Reactive ester resin C: 238 g / eq. of active ester group equivalent, naphthalene-type active ester resin synthesized in Synthesis Example 5, and a toluene solution with a solid content of 62%. HP-C-8000L-65MT: Active ester equivalent 220g / eq., manufactured by DIC, active ester resin, 65% solids MEK / toluene mixed solution. • Active ester resin A: Active ester equivalent 250 g / eq., active ester resin as shown in formula (e-1), and toluene solution with 60% solid content.

[0360] [Chemical Formula 28]

[0361] LA-3018-50P: 151 g / eq. hydroxyl equivalent, manufactured by DIC, a phenolic resin containing a triazine skeleton, 50% solids in a 1-methoxy-2-propanol solution. LA-1356: 146 g / eq. hydroxyl equivalent, manufactured by DIC, a phenolic resin containing a triazine backbone. SN-395: Hydroxyl equivalent 110 g / eq., manufactured by DIC, naphthol aralkyl type phenolic resin. GPH-65: Hydroxyl equivalent 198 g / eq., manufactured by Nippon Kayaku Co., Ltd., a biphenyl aryl phenolic resin. V-03: Active group equivalent 216 g / eq., manufactured by Nisshinbo Chemical Co., Ltd., carbodiimide resin, 50% solids toluene solution. • Active ester resin B: Active ester equivalent 214 g / eq., Active ester resin B synthesized in Synthesis Example 4, Toluene solution with 70% solids content. • Free radical polymerizable resin A: a toluene solution of the free radical polymerizable resin shown in formula (e-3) below, with an active ester equivalent of 250 g / eq. and a solid content of 70%.

[0362] [Chemical Formula 29]

[0363] (F) Polymer resin: YX7553BH30: A mixed solution of MEK / cyclohexanone with phenoxy resin and 30% solids content, manufactured by Mitsubishi Chemical Corporation. YL9142T30: A toluene solution of 30% solids, manufactured by Mitsubishi Chemical Corporation, containing phenoxy resin. PIAD200: A mixed solution of polyimide resin and 30% solids in cyclohexanone, dimethyl glycol, and methylcyclohexane, manufactured by Arakawa Chemical Co., Ltd. • Polyimide resin A: Polyimide resin A synthesized in Synthesis Example 6 • Polyimide resin B: Polyimide resin B synthesized in Synthesis Example 7.

[0364] (G) Organic filler materials: EXL-2655: A core-shell buffer packing material containing rubber components, manufactured by Dow Chemical.

[0365] (H) Curing accelerator: ·1B2PZ: Made by Shikoku Chemical Industry Co., Ltd., an imidazole curing accelerator, a MEK solution with 10% solid content.

[0366] (J) Solvent: MEK: Methyl Ethyl Ketone ECH: Ethylcyclohexane MCH: Methylcyclohexane ·THNA: Tetrahydronaphthalene ·DHNA: Decahydronaphthalene MAK: Methylpentyl ketone Toluene: Toluene ·1-Methoxy-2-propanol: 1-Methoxy-2-propanol.

[0367] <Experimental Example 1: Evaluation of Varnish Stability> For the resin varnishes obtained in the examples and comparative examples, a filtration process was performed to remove secondary aggregates of inorganic filler material and foreign matter from the resin varnishes. The filtration method was carried out by delivering the resin varnish through a mesh filter using a metering pump. The filtration pressure (differential pressure) was set to 0.4 MPa or less to prevent clogging of the mesh filter. Furthermore, a pump with minimal pulsation was used to maintain a constant filtration pressure. The mesh size of the filter was 10 μm to 30 μm.

[0368] The filtered resin varnish was observed using an optical microscope, and the number of precipitates with a particle size of 10 μm or larger was counted (initial). The filtered resin varnish was then stored at 4°C for 3 days. The stored resin varnish was then observed using an optical microscope, and the number of precipitates with a particle size of 10 μm or larger was counted (after 3 days of refrigeration).

[0369] The increase rate of precipitates is calculated using the following formula (M2): Increase rate = Number of precipitates (refrigerated for 3 days) / Number of precipitates (initial) (M2) The stability of the varnish is determined according to the following criteria: "Undesirable: The increase rate of precipitates is above 1.5%" "Good": The increase rate of precipitates is greater than 1.2 and less than 1.5. "Excellent": The increase rate of precipitates is less than 1.2%.

[0370] <Experimental Example 2: Determination of Dielectric Loss Tangent and Glass Transition Temperature> (1) Evaluation of membrane fabrication: As a support film, a PET film (50 μm thick, 240 mm square) was prepared, having a mold-treated side treated with mold release agent "1010" manufactured by Lintec Corporation and an untreated side. A glass cloth substrate epoxy resin double-sided copper-clad laminate (Panasonic "R5715ES", 0.7 mm thick, 255 mm square) was overlapped on the untreated side of the support film, and the four sides were fixed with polyimide adhesive tape (10 mm wide).

[0371] The resin varnish obtained in the examples and comparative examples was applied to the release agent-treated surface of the support film using a coating applicator, so that the thickness of the dried resin composition layer was 40 μm, and dried at 70°C to 100°C (average 100°C) for 3 minutes. The epoxy resin double-sided copper-clad laminate of the glass cloth substrate was removed to obtain resin sheet A having the support film and the resin composition layer.

[0372] (2) Evaluation of the preparation of the cured material: Resin sheet A was placed in an oven at 190°C and heated for 90 minutes to heat-cur the resin composition layer. After heat curing, the PET film was peeled off to obtain a sheet-like cured product. The resulting cured product was called the "evaluation cured product".

[0373] (3) Measurement of dielectric loss tangent: The cured material was cut to obtain a specimen with a width of 2 mm and a length of 80 mm. For this specimen, the dielectric loss tangent was measured using a testing apparatus (Agilent Technologies HP8362B) at a frequency of 5.8 GHz and a temperature of 23 °C via the resonant cavity perturbation method. Measurements were performed on two specimens, and the average value was calculated.

[0374] (4) Determination of glass transition temperature: The cured material was cut to obtain specimens approximately 5 mm wide and 15 mm long. These specimens were then subjected to thermomechanical analysis using a Rigaku Thermo Plus TMA8310 apparatus, employing the tensile loading method. Specifically, the specimens were mounted on the apparatus and subjected to two consecutive thermomechanical analyses (the first to 200 °C, the second to 260 °C) under a load of 1 g and a heating rate of 5 °C / min. The glass transition temperature was measured in the second thermomechanical analysis, and the results were evaluated based on the following criteria: "Good": Glass transition temperature above 150℃ "Poor": Glass transition temperature less than 150℃.

[0375] <Example 3: Insulation Reliability Test> An inner layer circuit board was prepared, comprising an imide film and comb-shaped electrodes (linewidth and line spacing (L / S) = 15 μm / 15 μm) formed on the imide film. Using a batch vacuum pressure laminator (MAKI Corporation "MVLP-500"), the inner layer circuit board was laminated with resin sheet A manufactured in Test Example 2, with the resin composition layer of resin sheet A bonded to the comb-shaped electrodes. Lamination was performed by depressurizing the pressure for 30 seconds to below 13 hPa, and then pressing at 100°C and 0.74 MPa for 30 seconds. The support film was then peeled off. The resin composition layer was then thermocured at 200°C for 90 minutes to obtain an evaluation laminate with a layer structure of "inner layer circuit board / cured layer".

[0376] The evaluation laminate was placed in a highly accelerated life testing apparatus (PM422, manufactured by Kusumoto Chemical Co., Ltd.) and stored for 300 hours at 130°C and 85% RH with an applied voltage of 3.3V. The insulation resistance of the cured layer was measured using the stored evaluation laminate. The insulation resistance was 1.0 × 10⁻⁶. 8 Insulation reliability is rated as "good" when the insulation resistance is above Ω, and "good" when the insulation resistance is less than 1.0 × 10 Ω. 8 In the case of Ω, the insulation reliability is rated as "poor".

[0377] <Experimental Example 4: Evaluation of surface roughness after wet decontamination> (1) Fabrication of resin sheets: As a support, a polyethylene terephthalate film (Lintec "AL5", 38 μm thick) with a release layer was prepared. The resin varnish obtained in the examples and comparative examples was uniformly coated on the release layer of the support to make the thickness of the dried resin composition layer 25 μm, and dried at 70°C to 80°C (average 75°C) for 2.5 minutes to obtain a resin sheet B comprising the support and the resin composition layer.

[0378] (2) Lamination of resin sheets: As an inner circuit board with copper foil on both sides, a glass cloth substrate epoxy resin double-sided copper-clad laminate (copper foil thickness 18μm, substrate thickness 0.4mm, Panasonic "R1515A") was prepared. The surfaces of the copper foil on both sides of this built-in circuit board were roughened using MEC "CZ8101" (copper etching depth 1.0μm).

[0379] A batch vacuum pressure laminator (Nikko-Materials' CVP700 2-stage stacking laminator) was used to laminate resin sheet B onto both sides of the inner circuit board in a manner that bonds the resin composition layer to the inner circuit board. This lamination was performed by adjusting the pressure to below 13 hPa after a 30-second depressurization, followed by pressing at 120°C and 0.74 MPa for 30 seconds. Next, a hot-press was performed at 100°C and 0.5 MPa for 60 seconds.

[0380] (3) Thermosetting of the resin composition layer: Then, the inner substrate with resin sheet B laminated on it is placed in an oven at 130°C and heated for 30 minutes, followed by heating in an oven at 170°C for 30 minutes to thermally cure the resin composition layer and form an insulating layer. Then, the support is peeled off to obtain a cured substrate A having an insulating layer, an inner substrate, and an insulating layer in sequence.

[0381] (4) Roughening treatment: The cured substrate A is subjected to a decontamination treatment as a roughening process. As a decontamination treatment, the following wet decontamination treatment is performed.

[0382] (Wet stain removal treatment) The cured substrate A was immersed in a swelling solution (an aqueous solution of Swelling Dip Securiganth P manufactured by Amtec Japan, diethylene glycol monobutyl ether, and sodium hydroxide) at 60°C for 5 minutes. Next, the cured substrate A was immersed in an oxidizing agent solution (an aqueous solution of Concentrate Compact CP manufactured by Amtec Japan, approximately 6% potassium permanganate, and approximately 4% sodium hydroxide) at 80°C for 15 minutes. Next, the cured substrate A was immersed in a neutralizing solution (an aqueous solution of Reduction Solution Securiganth P manufactured by Amtec Japan, sulfuric acid) at 40°C for 5 minutes. Then, the cured substrate A was dried at 80°C for 15 minutes. The cured substrate A that underwent the aforementioned wet decontamination treatment was designated as "evaluation substrate B".

[0383] (5) Determination of arithmetic mean roughness (Ra): The arithmetic mean roughness Ra of the insulating layer surface of evaluation substrate B was measured using a non-contact surface roughness meter (Veeco Instruments WYKO NT3300). The measurement was performed in VSI mode with a 50x lens and a measurement range of 121 μm × 92 μm. Measurements were taken at six locations. The average value at the six locations was calculated and rounded to the next decimal place, as shown in the table below.

[0384] <Example 5: Evaluation of Coating Peel Strength> (1) Formation of the conductor layer: According to the semi-additive method, a conductor layer is formed on the roughened surface of the insulating layer of evaluation substrate B. Specifically, the roughened evaluation substrate B is immersed in an electroless plating solution containing PdCl2 at 40°C for 5 minutes, followed by immersion in an electroless copper plating solution at 25°C for 20 minutes to form an electroless plating layer. Next, the evaluation substrate B is annealed at 150°C for 30 minutes. Then, a resist layer is formed on the electroless plating layer, and a pattern is formed by etching. Then, copper sulfate electrolytic plating is performed to form an electrolytic plating layer on the electroless plating layer. Through the above operations, a conductor layer with a thickness of 25 μm, consisting of the electroless plating layer and the electrolytic plating layer, is formed on the roughened surface of the insulating layer. Then, an annealing treatment is performed at 180°C for 30 minutes to obtain "evaluation substrate C".

[0385] (2) Determination of coating peel strength: The peel strength of the conductor layer and the insulating layer was measured using the obtained evaluation substrate C. This peel strength measurement was performed according to JIS C6481. Specifically, the peel strength was measured using the following procedures.

[0386] A rectangular section, 10 mm wide and 100 mm long, was cut into the conductor layer of evaluation substrate C. One end of this rectangular section was peeled off and clamped in a jig (TSE AUTO COM type testing machine "AC-50C-SL"). A 35 mm long section of this rectangular section was peeled vertically, and the peel load (kgf / cm) was measured as the plating peel strength. The peeling was performed at room temperature at a speed of 50 mm / min. A higher plating peel strength indicates better adhesion. Therefore, adhesion was judged according to the following criteria: "Good": The peel strength of the coating is above 0.4 kgf / cm. "Poor": The peel strength of the coating is less than 0.4 kgf / cm.

[0387] <Experimental Example 6: Evaluation Test of Membrane Flexibility> (1) Evaluation of the fabrication of resin sheets: As a support film, a PET film (50 μm thick, 240 mm square) was prepared, having a mold-treated side treated with mold release agent "1010" manufactured by Lintec Corporation and an untreated side. A glass cloth substrate epoxy resin double-sided copper-clad laminate (Panasonic "R5715ES", 0.7 mm thick, 255 mm square) was overlapped on the untreated side of the support film, and the four sides were fixed with polyimide adhesive tape (10 mm wide).

[0388] The resin varnish obtained in the examples and comparative examples was applied to the release agent-treated surface of the support film using a coating applicator, so that the thickness of the dried resin composition layer was 40 μm, and dried at 70°C to 100°C (average 100°C) for 3 minutes. The epoxy resin double-sided copper-clad laminate of the glass cloth substrate was removed to obtain a resin sheet C having the support film and the resin composition layer.

[0389] (2) MIT Experiment: Resin sheet C was cut to obtain a specimen with a width of 15 mm and a length of 110 mm. For this specimen, a bending test was performed according to JIS C-5016 using an MIT testing apparatus (MIT Flexural Fatigue Testing Machine "MIT-DA" manufactured by Toyo Seiki Co., Ltd.). In this bending test, resin sheet C was repeatedly bent under the conditions of a load of 2.5 N, a bending angle of 90°, a bending radius of 1.0 mm, and a bending speed of 175 times / minute. The number of flexural cycles until the resin composition layer in resin sheet C fractured was measured. The test was performed on 5 samples, and the average of the top 3 values ​​was calculated. Based on the calculated average value, the membrane flexibility was evaluated according to the following criteria: "Good": Can withstand more than 100 folds. "Poor": The number of folding cycles is less than 100.

[0390] <Example 7: Evaluation Test of the Adhesion Between the Resin Composition Layer and the Protective Film> (1) Manufacturing of resin sheets with protective film: The resin sheet C obtained above is laminated with a polypropylene film (ALPHAN MA-411, 15 μm thick, manufactured by Oji Specialty Paper Co., Ltd.) as a protective film to produce a resin sheet with a protective film. The lamination is performed such that the surface of the resin composition layer of the resin sheet C is bonded to the smooth surface of the protective film. The lamination is conducted at atmospheric pressure, 60°C, and a pressing pressure of 0.06 kgf / cm². 2 Implemented under the following conditions.

[0391] (2) Determination of the peel strength of the protective film relative to the resin composition layer: The resin sheet with the protective film described above is cut to obtain a test sample with a width of 30 mm and a length of 100 mm. The cutting is performed in such a way that the length direction of the protective film is parallel to the length direction of the test sample.

[0392] A double-sided adhesive tape (Nichiban Co., Ltd. "NICETACK") with a width of 25 mm and a length of 95 mm was attached to the surface of the support film side of the obtained test sample. This double-sided adhesive tape was bonded to a piece of paper material (Jitsuta Co., Ltd. "Kona Yuki 210 (Extra Thick)") cut to a width of 27 mm and a length of 100 mm. One end of the protective film was peeled off and held in place with a clamp. At room temperature (23°C), the protective film was stretched vertically at a speed of 50 mm / min, and the load at which the protective film was peeled off 30 mm was measured as the peel strength SB. A tensile testing machine (TSE Co., Ltd. "AC-50C-SL") was used for this test. Based on the measured peel strength SB, the adhesion between the resin composition layer and the protective film was evaluated according to the following criteria: "Excellent": Peel strength SB is above 0.003 kgf / cm and below 0.006 kgf / cm. "Good": Peel strength SB is greater than 0.006 kgf / cm. "Poor": Peel strength SB is less than 0.003 kgf / cm.

[0393] <Results> The results of the above-described examples and comparative examples are shown in the following table. In the table below, the content (mass%) of components (A) to (H) represents the ratio of 100% by mass of the non-volatile components in the resin varnish. Furthermore, the content (mass%) of methyl ethyl ketone, cyclohexanone, component (J-1), toluene, and 1-methoxy-2-propanol represents the ratio of 100% by mass of the total amount of the resin varnish. Additionally, the content (mass%) of component (J-1) in all solvents represents the ratio of 100% by mass of all solvents. Furthermore, the meanings of the abbreviations are as follows: NV: Concentration of non-volatile components MEK: Methyl Ethyl Ketone ECH: Ethylcyclohexane MCH: Methylcyclohexane THNA: Tetrahydronaphthalene DHNA: Decahydronaphthalene MAK: Methylpentyl ketone Solubility of flame retardant: Solubility of flame retardant in cyclohexanone Df: Dielectric loss tangent Tg: Glass transition temperature Ra: Arithmetic mean roughness.

[0394] [Table 2]

[0395] [Table 3]

Claims

1. A resin composition comprising (A) an epoxy resin, (B) a maleimide resin, (C) an inorganic filler, and (D) a cyclic phosphazene compound represented by the following formula (1), ###0001### (1) wherein The amount of the (C) inorganic filler is 60% by mass or more, relative to 100% by mass of nonvolatile components of the resin composition, In the formula (1), R 1 and R 2 (i) each independently represents a nitro group, an alkyl group or alkoxy group having 1 to 8 carbon atoms optionally substituted with at least one selected from an alkyl group having 1 to 6 carbon atoms and an aryl group, and an aryl group or aryloxy group having 6 to 20 carbon atoms optionally substituted with at least one selected from an alkyl group having 1 to 6 carbon atoms and an aryl group, or (ii) forms, together with each other, a saturated or unsaturated cyclic structure optionally substituted with an alkyl group having 1 to 6 carbon atoms or a carbonyl group; L represents a divalent hetero atom; a and b each independently represent an integer of 0 to 4; m each independently represents 0 or 1; n represents an integer of 3 to 8; the structures of the repeating units are each independent. The amount ratio of the (B) maleimide resin to the (A) epoxy resin, i.e., (B) maleimide resin / (A) epoxy resin, is 0.01 or more and 2.0 or less on a mass basis.

2. The resin composition according to claim 1, wherein, The amount ratio of the (B) maleimide resin to the (A) epoxy resin, i.e., (B) maleimide resin / (A) epoxy resin, is less than 0.6 on a mass basis.

3. The resin composition according to claim 2, wherein, The amount of the (A) epoxy resin is 1% by mass or more and 30% by mass or less, relative to 100% by mass of nonvolatile components of the resin composition.

4. The resin composition according to claim 1, wherein, The amount of the (B) maleimide resin is 0.1% by mass or more and 20% by mass or less, relative to 100% by mass of nonvolatile components of the resin composition.

5. The resin composition according to claim 1, wherein, The amount of the (C) inorganic filler is 90% by mass or less, relative to 100% by mass of nonvolatile components of the resin composition.

6. The resin composition according to claim 1, wherein, The amount of the (D) cyclic phosphazene compound is 0.1% by mass or more and 5% by mass or less, relative to 100% by mass of nonvolatile components of the resin composition.

7. The resin composition according to claim 1, wherein The amount of the (D) cyclic phosphazene compound is 0.01% by mass or more and 5% by mass or less, relative to 100% by mass of the inorganic filler.

8. The resin composition according to claim 1, wherein, The (D) cyclic phosphazene compound is a particle having an average particle diameter of 1.5 μm or less.

9. The resin composition according to claim 1, wherein, The (D) cyclic phosphazene compound is a particle having an average particle diameter of 0.8 μm or less.

10. The resin composition according to claim 1, wherein, The resin composition does not contain a cyclic phosphazene compound other than the (D) component.

11. The resin composition according to claim 10, wherein, The resin composition is not in a fibrous form.

12. The resin composition according to claim 10, wherein, 13. The resin composition according to claim 1, wherein The (D) cyclic phosphazene compound has a melting point of 260°C or more. (D) The cyclic phosphazene compound is a particle having an average particle diameter of D a μm, (C) the average particle size of the inorganic filler material is D b μm, D a / D b is 0.1 or more and 10 or less.

14. The resin composition according to claim 13, wherein, D a / D b is 1.5 or less.

15. The resin composition according to claim 1, wherein, In the case where the first dissolution test is performed, the amount of the (D) cyclic phosphazene compound dissolved is 0.04 g or less, 16. The resin composition according to claim 1, wherein, The first dissolution test is a test in which the (D) cyclic phosphazene compound is dissolved in cyclohexanone 10 g by ultrasonic treatment at 25°C for 10 minutes. In the case where the second dissolution test is performed, the amount of the (D) cyclic phosphazene compound dissolved is 0.3 g or less, 17. The resin composition according to claim 1, wherein, The second dissolution test is a test in which the (D) cyclic phosphazene compound is dissolved in cyclohexanone 10 g by ultrasonic treatment at 70°C for 10 minutes. The resin composition contains a ketone-based solvent.

18. The resin composition according to claim 1, wherein, ​ 19. The resin composition according to claim 1, wherein, The resin composition contains (J) a solvent, The (J) solvent contains (J-1) a non-aromatic high-boiling solvent having no aromatic ring in the molecule and having a boiling point of 100°C or higher.

20. The resin composition according to claim 19, wherein, The amount of the (J-1) non-aromatic high-boiling solvent is 20 mass% or less relative to 100 mass% of the total amount of the (J) solvent.

21. The resin composition of claim 19, wherein, The amount of the (J-1) non-aromatic high-boiling solvent is 4.8 mass% or less relative to 100 mass% of the total amount of the resin composition.

22. The resin composition according to claim 1, wherein, The (B) maleimide resin contains an aromatic maleimide resin.

23. A resin sheet provided with a support and a resin composition layer formed on the support, The resin composition layer contains the resin composition according to any one of claims 1 to 22.

24. A cured product of the resin composition according to any one of claims 1 to 22.

25. A circuit substrate containing a cured product of the resin composition according to any one of claims 1 to 22.

26. A semiconductor device containing the circuit substrate according to claim 25.

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