Resin sheet, method for producing the same, method for manufacturing circuit board, and resin composition

Abstract

To provide a resin sheet capable of forming an insulating layer while suppressing unevenness.SOLUTION: The resin sheet includes a resin composition layer. The resin composition layer contains (A) a curable resin containing a furan skeleton, (B) tetrahydrofuran, and (C) an inorganic filler. The amount of the curable resin (A) having a furan skeleton is 2 mass% or more based on 100 mass% of the total amount of the resin composition layer. The amount of the tetrahydrofuran (B) is 0.1 mass% or more based on 100 mass% of the total amount of the resin composition layer. The amount of the inorganic filler (C) is 50 mass% or more based on 100 mass% of a nonvolatile component of the resin composition layer.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a resin sheet and a method for producing the same, a method for producing a circuit board using the resin sheet, and a resin composition used in producing the resin sheet. [Background technology]

[0002] Circuit boards such as printed wiring boards are widely used in various electronic devices. A known method for manufacturing a circuit board is a build-up method in which insulating layers and conductor layers are alternately stacked on an inner layer board. The insulating layer is formed, for example, from a cured product of a resin composition. As a specific example, a resin composition layer containing a resin composition is formed, and the resin composition layer is cured to form an insulating layer containing a cured product of the resin composition.

[0003] In recent years, from the viewpoint of sustainability, the use of biomass resins as materials for insulating layers has been considered. Resins containing a furan skeleton are known as one of the biomass resins with excellent insulating properties (Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6631889 [Patent Document 2] JP 2016-060766 A Summary of the Invention [Problem to be solved by the invention]

[0005] Generally, biomass resins have low heat resistance, but resins containing a furan skeleton have high heat resistance. In addition, resins containing a furan skeleton have a relatively small linear thermal expansion coefficient. Therefore, the present inventors attempted to form an insulating layer using a curable resin containing a furan skeleton.

[0006] Specifically, the present inventors attempted to manufacture a resin composition containing an inorganic filler in combination with a curable resin containing a furan skeleton in order to improve the dielectric tangent and the linear thermal expansion coefficient, and to form an insulating layer using a resin sheet provided with a resin composition layer containing the resin composition. However, it was found that when an insulating layer was formed by this method, unevenness occurred in the insulating layer.

[0007] The unevenness of the insulating layer was generated in detail as follows. Usually, the method of forming an insulating layer using a resin sheet includes laminating a resin sheet and an inner layer substrate so that the resin composition layer and the inner layer substrate are bonded to each other, and curing the resin composition layer to obtain an insulating layer. However, in the vicinity of the edge of the formed insulating layer, a concave-shaped unevenness was observed along the edge.

[0008] The present invention has been devised in view of the above-mentioned problems, and aims to provide a resin sheet and a manufacturing method thereof capable of forming an insulating layer while suppressing unevenness; a manufacturing method for a circuit board using the resin sheet; and a resin composition from which the resin sheet can be manufactured. [Means for solving the problem]

[0009] The present inventors have conducted extensive research to solve the above problems, and as a result, have found that the above problems can be solved by combining a curable resin containing a specific amount of a furan skeleton, a specific amount of tetrahydrofuran (THF), and a specific amount of an inorganic filler, and have completed the present invention. That is, the present invention includes the following.

[0010] <1> A resin sheet having a resin composition layer, the resin composition layer contains (A) a curable resin containing a furan skeleton, (B) tetrahydrofuran, and (C) an inorganic filler; (A) the amount of the curable resin containing a furan skeleton is 2% by mass or more with respect to 100% by mass of the total amount of the resin composition layer; (B) the amount of tetrahydrofuran is 0.1% by mass or more with respect to 100% by mass of the total amount of the resin composition layer; (C) A resin sheet, in which the amount of an inorganic filler is 50% by mass or more relative to 100% by mass of the nonvolatile components of the resin composition layer. <2> The biomass ratio of the non-volatile components in the resin composition layer, represented by the following formula (M2), is 0.1 mass% or more. <1> The resin sheet according to claim 1. Biomass ratio (mass%) = (mass of biological components in non-volatile components / mass of non-volatile components) × 100 (M2) <3> The average linear thermal expansion coefficient of the cured layer obtained by curing the resin composition layer is 50 ppm / °C or less; <1> or <2> The resin sheet according to claim 1. <4> The dielectric loss tangent of the cured layer obtained by curing the resin composition layer is less than 0.015. <1> ~ <3> The resin sheet according to any one of claims 1 to 7. <5> The glass transition temperature of the cured layer obtained by curing the resin composition layer is higher than 150°C. <1> ~ <4> The resin sheet according to any one of claims 1 to 7. <6> <1> ~ <5> A method for producing a circuit board using the resin sheet according to any one of the preceding claims, The manufacturing method comprises: laminating the resin sheet and the inner layer substrate so that the resin composition layer and the inner layer substrate are bonded to each other; A step of curing the resin composition layer; A method for manufacturing a circuit board, comprising: <7> A resin composition comprising (A) a curable resin containing a furan skeleton, (B) tetrahydrofuran, and (C) an inorganic filler, (A) the amount of the curable resin containing a furan skeleton is 2% by mass or more relative to 100% by mass of the total amount of the resin composition; (B) the amount of tetrahydrofuran is 1% by mass or more based on 100% by mass of the total amount of the resin composition; (C) A resin composition, in which the amount of an inorganic filler is 50% by mass or more relative to 100% by mass of the nonvolatile components in the resin composition. <8> <7> A method for producing a resin sheet using the resin composition according to claim 1, The manufacturing method comprises: A step of applying a resin composition onto a support; A step of drying the applied resin composition to form a resin composition layer; Includes; A method for producing a resin sheet, wherein the amount of (B) tetrahydrofuran in the resin composition layer is 0.1 mass % or more relative to 100 mass % of the total amount of the resin composition layer. Effect of the Invention

[0011] According to the present invention, it is possible to provide a resin sheet capable of forming an insulating layer while suppressing unevenness and a manufacturing method thereof; a manufacturing method for a circuit board using the resin sheet; and a resin composition capable of manufacturing the resin sheet. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] The present invention will be described below with reference to embodiments and examples. However, the present invention is not limited to the embodiments and examples shown below, and may be modified and implemented within the scope of the claims and their equivalents.

[0013] As used herein, the term "optionally substituted" in reference to a compound or group means both the case where none of the hydrogen atoms of the compound or group are substituted with a substituent, and the case where some or all of the hydrogen atoms of the compound or group are substituted with a substituent.

[0014] <Resin Sheet Overview> The resin sheet according to one embodiment of the present invention includes a resin composition layer. The resin composition layer includes a combination of a specific amount of (A) a curable resin containing a furan skeleton, a specific amount of (B) tetrahydrofuran, and a specific amount of (C) an inorganic filler. Hereinafter, the "curable resin containing a furan skeleton (A)" may be referred to as "furan-type curable resin (A)". By using the resin sheet according to this embodiment, an insulating layer can be formed while suppressing unevenness.

[0015] The present inventors speculate that the mechanism by which the above-mentioned effects are obtained is as follows, however, the technical scope of the present invention is not limited to the mechanism below.

[0016] When a resin sheet is laminated with an inner layer substrate, heat and pressure are generally applied to the resin composition layer of the resin sheet. In this case, since the edge of the resin composition layer is generally open during lamination, the resin composition contained in the resin composition layer tends to flow easily near the edge of the resin composition layer.

[0017] Furthermore, in a conventional resin composition layer containing a furan type curable resin (A) and an inorganic filler (C), the compatibility of each component contained in the resin composition layer is generally low. In particular, the compatibility of the furan type curable resin (A) with components other than the furan type curable resin (A) is low.

[0018] In a resin composition layer in which the compatibility of each component is low, when heat and pressure are applied near the edge of the resin composition layer, some components are easy to move and other components are difficult to move, and thus differences in fluidity may occur for each component. When differences in fluidity occur in this way, the composition of the resin composition layer may become biased. When the composition bias occurs near the edge of the resin composition layer, some components may locally flow significantly, causing depressions and forming unevenness. These depressions were often formed as numerous streaky depressions.

[0019] In contrast, in this embodiment, (B) tetrahydrofuran is further combined. Since the furan skeleton contained in (A) furan type curable resin and the molecular skeleton of (B) tetrahydrofuran are similar, (A) furan type curable resin and (B) tetrahydrofuran have high compatibility. In addition, (B) tetrahydrofuran can function as a good solvent with excellent compatibility with various resins. Therefore, since the compatibility of the components contained in the resin composition layer can be improved overall while containing (A) furan type curable resin and (C) inorganic filler, according to the resin sheet of this embodiment, the uniformity of the composition can be maintained high even when the resin sheet is laminated with an inner layer substrate. Therefore, it is possible to suppress the occurrence of large localized flow of some components during lamination, and therefore it is possible to suppress unevenness during the formation of the insulating layer.

[0020] (A) Furan type curable resin can usually be produced from biomass raw materials. Therefore, the resin sheet according to the present embodiment using (A) furan type curable resin can increase the biomass ratio and therefore reduce dependency on fossil resources, thereby contributing to environmental improvement from the viewpoint of sustainability.

[0021] Furthermore, the insulating layer formed using the resin sheet according to this embodiment can usually have a small average linear thermal expansion coefficient, so that it is possible to suppress warping of the circuit board. Also, the insulating layer formed using the resin sheet according to this embodiment can usually have a low dielectric tangent, so that it can contribute to reducing signal loss of the circuit board. Furthermore, the insulating layer formed using the resin sheet according to this embodiment can usually have a high glass transition temperature, so that it can improve the heat resistance of the circuit board.

[0022] <(A) Furan-type curable resin> The resin composition layer of the resin sheet contains a furan-type curable resin (A) as the component (A). The furan-type curable resin (A) is a curable resin containing a furan skeleton. Therefore, the furan-type curable resin (A) can react under appropriate conditions to form bonds and cure the resin composition layer. The furan-type curable resin (A) may be a thermosetting resin or a photocurable resin, but is preferably a thermosetting resin.

[0023] The (A) furan type curable resin may be a resin in which the furan skeleton reacts to form a bond. The (A) furan type curable resin may also be a resin that contains an active group other than the furan skeleton and in which the active group reacts to form a bond. Examples of the active group include an epoxy group, a hydroxyl group (phenolic hydroxyl group) bonded to an aromatic ring, an active ester group, a cyanate group, a carbodiimide group, an acid anhydride group, an amino group, and a radically reactive unsaturated group.

[0024] The radical reactive unsaturated group may, for example, be a group containing a non-aromatic carbon-carbon unsaturated bond.Specific examples of the radical reactive unsaturated group include unsaturated hydrocarbon groups such as vinyl group, allyl group, 1-propenyl group, 3-cyclohexenyl group, 3-cyclopentenyl group, 2-vinylphenyl group, 3-vinylphenyl group, and 4-vinylphenyl group; and α,β-unsaturated carbonyl groups such as acryloyl group, methacryloyl group, and maleimide group (2,5-dihydro-2,5-dioxo-1H-pyrrol-1-yl group).

[0025] The number of active groups contained in one molecule of (A) furan type curable resin may be 1 or 2 or more. When (A) furan type curable resin contains two or more active groups, the two or more active groups may be the same or different. Furthermore, (A) furan type curable resin may be one in which the furan skeleton can react to form a bond and the active group can react.

[0026] Among the above, a furan-type curable resin containing an active ester group is preferred. Therefore, the (A) furan-type curable resin preferably contains a furan-type curable resin containing an active ester group, and may contain only a furan-type curable resin containing an active ester group. A furan-type curable resin containing an active ester group does not usually generate a polar group such as a hydroxyl group by a reaction during curing. Therefore, the polarity of the insulating layer can be reduced, and therefore the dielectric loss tangent of the insulating layer can be reduced.

[0027] A preferred example of the furan-type curable resin containing an active ester group is a resin represented by the following formula (A-1).

[0028] [ka]

[0029] (In formula (A-1), R a1 and R a2 each independently represents a monovalent aromatic group which may have a substituent; A aeach independently represents a group represented by the following formula (A-1-1) or formula (A-1-2); a represents the number of repetitions, 0≦n a ≦8.)

[0030] [ka]

[0031] (In formula (A-1-1), R a11 , and R a12 each independently represents a divalent aromatic group which may have a substituent; L a11 each independently represents a single bond or a divalent linking group; R a11 and L a11 may be bonded together to form a ring. a represents a number in the range of 0 to 5.)

[0032] [ka]

[0033] (In formula (A-1-2), R a13 , and R a14 each independently represents a divalent aromatic group which may have a substituent; L a12 represents a group represented by formula (A-1-3). a and c a Each independently represents a number ranging from 0 to 5.

[0034] [ka]

[0035] (In formula (A-1-3), R a15 , and R a16 each independently represents a divalent aromatic group which may have a substituent; L a13 each independently represents a single bond or a divalent linking group; R a15 and L a13may be joined together to form a ring. d a represents a number in the range of 0 to 5.)

[0036] In formula (A-1), R a1 and R a2 Each of the groups independently represents a monovalent aromatic group which may have a substituent. The monovalent aromatic group refers to a group in which one hydrogen atom is removed from an aromatic ring of an aromatic compound. The term "aromatic ring" refers to a ring that follows the Huckel rule, in which the number of electrons contained in the π electron system on the ring is 4n+2 (n is a natural number). The term "aromatic ring" includes a monocyclic aromatic ring and a fused aromatic ring in which two or more monocyclic aromatic rings are fused. The aromatic ring may be a carbocyclic ring or a heterocyclic ring. Examples of the monovalent aromatic group which may have a substituent include an aryl group which may have a substituent and a heteroaryl group which may have a substituent. The number of carbon atoms of the monovalent aromatic group is preferably 3 or more, more preferably 4 or more, even more preferably 5 or more, and even more preferably 6 or more. The upper limit is preferably 24 or less, more preferably 18 or less, even more preferably 14 or less, and even more preferably 10 or less. The number of carbon atoms of the substituent is not included in this number of carbon atoms.

[0037] The monovalent aromatic group which may have a substituent is preferably an aryl group which may have a substituent, from the viewpoint of obtaining an insulating layer having a high glass transition temperature. a1 and R a2 The number of carbon atoms of the aryl group in R is preferably 6 to 20, more preferably 6 to 14, and further preferably 6 to 12. The number of carbon atoms does not include the number of carbon atoms of the substituent. a1 and R a2 The optionally substituted monovalent aromatic group represented by the formula (I) is preferably an optionally substituted phenyl group, an optionally substituted naphthyl group, or an optionally substituted biphenyl group; more preferably an optionally substituted phenyl group or an optionally substituted naphthyl group; and even more preferably an optionally substituted naphthyl group.

[0038] R a1and R a2 Examples of the substituent in the monovalent aromatic group that may have the substituent include a halogen atom, an alkyl group, a cycloalkyl group, an alkoxy group, an alkenyl group, a cycloalkyloxy group, an aryl group, an aryloxy group, an arylalkyl group, an arylalkoxy group, a monovalent heterocyclic group, an alkylidene group, an amino group, a silyl group, an acyl group, an acyloxy group, a carboxy group, a sulfo group, a cyano group, a nitro group, a hydroxy group, a hydroxyalkyl group, a mercapto group, and an oxo group. Among them, monovalent hydrocarbon groups such as alkyl groups, cycloalkyl groups, alkenyl groups, aryl groups, and arylalkyl groups are preferred; monovalent saturated hydrocarbon groups such as alkyl groups and cycloalkyl groups are more preferred; and a bornyl group is even more preferred.

[0039] In formula (A-1), A a each independently represents a group represented by formula (A-1-1) or formula (A-1-2).

[0040] In formula (A-1-1), R a11 , and R a12 Each independently represents a divalent aromatic group which may have a substituent. A divalent aromatic group refers to a group in which two hydrogen atoms have been removed from an aromatic ring of an aromatic compound. Examples of the divalent aromatic group which may have a substituent include an arylene group which may have a substituent and a heteroarylene group which may have a substituent. The number of carbon atoms in the divalent aromatic group is preferably 3 or more, more preferably 4 or more, even more preferably 5 or more, and even more preferably 6 or more. The upper limit is preferably 30 or less, more preferably 24 or less, even more preferably 18 or less, even more preferably 14 or less, and even more preferably 10 or less. The number of carbon atoms in the substituent is not included in the number of carbon atoms. In a preferred example, R a11 , and R a12The optionally substituted divalent aromatic group represented by the formula (I) is preferably an optionally substituted phenylene group, an optionally substituted naphthylene group, an optionally substituted phenylene-fluorenylidene-phenylene group, or an optionally substituted biphenylene group; more preferably an optionally substituted phenylene group or an optionally substituted naphthylene group; and even more preferably an optionally substituted phenylene group.

[0041] R a11 and R a12 Examples of the substituent in the optionally substituted divalent aromatic group include R a1 and R a2 Examples of the substituents are the same as those of the monovalent aromatic group which may have a substituent. Among them, an alkyl group, an alkenyl group, an arylalkyl group, and a hydroxy group are preferred; an arylalkyl group and a hydroxy group are more preferred; and a benzyl group and a hydroxy group are further preferred.

[0042] In formula (A-1-1), L a11 each independently represents a single bond or a divalent linking group. Examples of the divalent linking group include a divalent organic group consisting of one or more (for example, 1 to 3000, 1 to 1000, 1 to 100, or 1 to 50) skeletal atoms selected from carbon atoms, oxygen atoms, nitrogen atoms, and sulfur atoms; an oxygen atom, a carbonyl group, a sulfonyl group, a divalent aliphatic group which may have a substituent, or a divalent aromatic group which may have a substituent is preferred. In a preferred example, L a11 L is a single bond, a divalent aliphatic group which may have a substituent, an oxygen atom, a divalent aromatic group which may have a substituent, a carbonyl group, or a sulfonyl group; more preferably, it is a divalent aliphatic group which may have a substituent. a11 The divalent aliphatic group in may be a divalent chain aliphatic group or a divalent cyclic aliphatic group.

[0043] L a11The divalent chain aliphatic group in may be a saturated chain aliphatic group such as an alkylene group; or may be an unsaturated chain aliphatic group such as an alkenylene group or an alkapolyenylene group. The number of carbon atoms in the divalent chain aliphatic group is preferably 1 to 12, more preferably 1 to 6, and even more preferably 1 to 4. The number of carbon atoms in the substituent is not included in the number of carbon atoms. Examples of the divalent chain aliphatic group include alkylene groups such as a methylene group, an ethylene group, a propylene group, an isopropylene group, a 1,1-dimethyl-3-methylpropylene group, a butylene group, a pentylene group, and a hexylene group; and alkenylene groups such as an ethenylene group, a propenylene group, a butenylene group, a pentenylene group, and a hexenylene group.

[0044] L a11 The divalent cyclic aliphatic group in may be a monocyclic cyclic aliphatic group or a polycyclic cyclic aliphatic group containing a plurality of ring structures. The number of carbon atoms in the divalent cyclic aliphatic group is preferably 3 to 15, more preferably 3 to 12, and even more preferably 3 to 10. The number of carbon atoms in the substituent is not included in the number of carbon atoms. Examples of the divalent cyclic aliphatic group include a cyclopropylene group, a cyclobutylene group, a cyclopentylene group, a cyclohexylene group, a decahydronaphthalene group, a norbornanylene group, a dicyclopentanylene group, an adamantanylene group, a cyclopropenylene group, a cyclobutenylene group, a cyclopentenylene group, a cyclohexenylene group, and a norbornenylene group, and a dicyclopentanylene group is preferable.

[0045] L a11 Examples of the substituent in the divalent aliphatic group which may have a substituent include a halogen atom, an alkoxy group, an alkenyl group, a cycloalkyloxy group, an aryl group, an aryloxy group, an arylalkoxy group, a monovalent heterocyclic group, an amino group, a silyl group, an acyl group, an acyloxy group, a carboxy group, a sulfo group, a cyano group, a nitro group, a hydroxy group, a mercapto group, and an oxo group. a11 Examples of the substituent in the optionally substituted divalent aromatic group include R a1 and R a2The substituents are the same as those in the monovalent aromatic group which may have a substituent.

[0046] R a11 and L a11 may be joined together to form a ring. a11 and L a11 When they are joined together to form a ring, L a11 is preferably a divalent aliphatic group which may have a substituent, and more preferably an alkylene group which may have a substituent. a If is 1, R a11 and L a11 are preferably bonded together to form a ring. a11 and L a11 are preferably linked together to form an indane ring.

[0047] In formula (A-1-1), a a represents a number in the range of 0 to 5, preferably a number in the range of 0 to 4, more preferably a number in the range of 0 to 3, and further preferably a number in the range of 0 to 2. a If is 1, then R a11 and L a11 are preferably linked together to form a ring.

[0048] In formula (A-1-2), R a13 and R a14 R each independently represents a divalent aromatic group which may have a substituent. a13 and R a14 The divalent aromatic group which may have a substituent is represented by R a11 It may be the same as the optionally substituted divalent aromatic group represented by: When the divalent aromatic group has a substituent, the substituent is preferably an alkyl group, more preferably a methyl group.

[0049] In formula (A-1-2), L a12 represents a group represented by formula (A-1-3).

[0050] In formula (A-1-3), R a15 and R a16 R each independently represents a divalent aromatic group which may have a substituent. a15 and R a16 The divalent aromatic group which may have a substituent is represented by R a11 It may be the same as the optionally substituted divalent aromatic group represented by: When the divalent aromatic group has a substituent, the substituent is preferably an alkyl group, more preferably a methyl group.

[0051] In formula (A-1-3), L a13 Each of L independently represents a single bond or a divalent linking group. a13 is R a15 may be bonded together with L to form a ring. a13 The divalent linking group is L in formula (A-1-1). a11 In a preferred example, L a13 The divalent linking group represented by the following formula (1) is an alkylene group having 1 to 12 carbon atoms which may have a substituent.

[0052] In formula (A-1-3), d a represents a number ranging from 0 to 5, and a in formula (A-1-1) a may be the same as the number in the range of 0 to 5 represented by R a15 and L a13 may be joined together to form a ring, and in particular d a When is 1, it preferably forms a ring.

[0053] In formula (A-1-2), b a and c a each independently represents a number in the range of 0 to 5, preferably a number in the range of 0 to 4, more preferably a number in the range of 0 to 3, and even more preferably a number in the range of 0 to 2.

[0054] Among them, A in formula (A-1) aExamples of the group include groups represented by the following formulas (1a) to (13a). a 1 represents a number in the range of 0 to 4, and b a 1 and c a 1 independently represents a number ranging from 0 to 5, e a and f a is 1≦e a +f a A number of 0 or more that satisfies ≦4, and "*" indicates a binding site. a 1 is a in formula (A-1-1) a is the value obtained by subtracting 1 from b a 1 and c a 1 is b in formula (A-1-2) a and c a is the same as:

[0055] [ka]

[0056] In formula (A-1), n a represents the number of repetitions, 0≦n a Satisfies ≦8. n a is preferably 2 or more, more preferably 3 or more, even more preferably 4 or more, and is preferably 7 or less, more preferably 6 or less, even more preferably 5 or less.

[0057] Specific examples of the resin represented by formula (A-1) include the following resins.

[0058] [ka]

[0059] [ka]

[0060] [ka]

[0061] [ka]

[0062] The resin represented by formula (A-1) can be produced, for example, by a production method including a condensation reaction of a hydroxyl group-containing aromatic compound having a phenolic hydroxyl group, a dicarboxylic acid halide having a furan skeleton, and a divalent phenol compound.

[0063] The hydroxyl group-containing aromatic compound is a compound in which a hydroxyl group is bonded to a monovalent aromatic group, and the aromatic group of the compound is represented by R a1 and R a2 Examples of such compounds include 1-naphthol, phenol, and orthophenylphenol.

[0064] The dicarboxylic acid halide having a furan skeleton is a compound in which two carbonyl halides are bonded to a furan skeleton. Examples of such compounds include 2,5-furandicarboxylic acid chloride and 2,5-thiophenedicarboxylic acid chloride. When using a compound having a furan skeleton derived from biomass, the compound having a furan skeleton derived from biomass may be chlorinated before being used as a raw material for the resin represented by formula (A-1).

[0065] The divalent phenol compound is a compound in which a dicarboxylic acid halide having a furan skeleton can react with a phenol moiety of the phenol compound, and A in formula (A-1) a Examples of such compounds include dicyclopentadiene-phenol polyadducts, 4,4'-(9-fluorenylidene)diphenol, 4,4'-dihydroxydiphenyl ether, 4,4'-dihydroxybenzophenone, bisphenol A, bisphenol F, 2,2'-diallylbisphenol A, bisphenol S, 4,4'-dihydroxybiphenyl, and 2,7-naphthalenediol.

[0066] In the condensation reaction, a catalyst such as a phase transfer catalyst, for example, tetra-n-butylammonium bromide, may be used as necessary. In addition, in the condensation reaction, a base may be used. Examples of the base include alkali metal hydroxides, such as sodium hydroxide (caustic soda) and potassium hydroxide; and tertiary amines, such as triethylamine, pyridine, and N,N-diisopropylethylamine. The reaction temperature may be, for example, in the range of 0°C to 80°C. In addition, the reaction time may be, for example, in the range of 30 minutes to 8 hours.

[0067] Another example of a preferred furan-type curable resin containing an active ester group is a resin represented by the following formula (A-2).

[0068] [ka]

[0069] (In formula (A-2), Ar b1 and Ar b2 each independently represents a divalent aromatic group which may have a substituent; L b1 represents a single bond or a divalent linking group, Ar b1 and L b1 may be joined together to form a ring; X b1 and X b2 each independently represents a substituent; b and b b each independently represents an integer of 0 to 3; n b represents 0 or 1.)

[0070] In formula (A-2), Ar b1 and Ar b2 each independently represents a divalent aromatic group which may have a substituent. b1 and Ar b2 The divalent aromatic group which may have a substituent is represented by R a11It may be the same as the optionally substituted divalent aromatic group represented by: When the divalent aromatic group has a substituent, the substituent is preferably an alkyl group, more preferably a methyl group.

[0071] In formula (A-2), L b1 represents a single bond or a divalent linking group. b1 Ar b1 may be bonded together with L to form a ring. b1 The divalent linking group is L in formula (A-1-1). a11 In a preferred example, L b1 The divalent linking group represented by the formula (I) is a divalent alicyclic group which may have a substituent, and is preferably a cyclohexylene group which may have a substituent. The substituent is preferably an alkyl group, and more preferably a methyl group.

[0072] In formula (A-2), X b1 and X b2 Each of X independently represents a substituent. b1 and X b2 is R in formula (A-1-1). a1 and R a2 may be the same as the substituent in the monovalent aromatic group which may have a substituent.

[0073] In formula (A-2), a b and b b each independently represents an integer of 0 to 3, preferably 0 or 1, and more preferably 0.

[0074] In formula (A-2), n b represents 0 or 1.

[0075] Specific examples of the resin represented by formula (A-2) include the following resins.

[0076] [ka]

[0077] The resin represented by formula (A-2) is commercially available. Examples of commercially available products of the resin represented by formula (A-2) include "BPTMC-FE" (resin represented by formula (b-1)) manufactured by Honshu Chemical Industry Co., Ltd., "BP-FE" (resin represented by formula (b-2)) manufactured by Honshu Chemical Industry Co., Ltd., and "TMPBP-FE" (resin represented by formula (b-3)) manufactured by Honshu Chemical Industry Co., Ltd.

[0078] Among the (A) furan type curable resins, a furan type curable resin containing a radically reactive unsaturated group other than the furan skeleton is preferred. Therefore, the (A) furan type curable resin preferably contains a furan type curable resin containing a radically reactive unsaturated group other than the furan skeleton, and may contain only the furan type curable resin containing the radically reactive unsaturated group. The furan type curable resin containing a radically reactive unsaturated group does not usually generate a polar group by reaction during curing. Therefore, the polarity of the insulating layer can be reduced, and therefore the dielectric loss tangent of the insulating layer can be reduced.

[0079] An example of a furan-type curable resin that contains a radically reactive unsaturated group in addition to a furan skeleton is a resin represented by the following formula (A-3).

[0080] [ka]

[0081] (In formula (A-3), R c1 , R c2 and R c3 each independently represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms; R c4 represents a divalent aliphatic group which may have a substituent; X c each independently represents a substituent; c represents an integer from 0 to 3.)

[0082] In formula (A-3), R c1 , R c2 and R c3each independently represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. c1 and R c2 is preferably a hydrogen atom, and R c3 is preferably a hydrogen atom or a methyl group.

[0083] In formula (A-3), R c4 R represents a divalent aliphatic group which may have a substituent. c4 The divalent aliphatic group which may have a substituent is represented by L in formula (A-1-1). a11 may be the same as the divalent aliphatic group which may have a substituent described as an example of R c4 is preferably an alkylene group, more preferably a methylene group.

[0084] In formula (A-3), X c Each of X independently represents a substituent. c is R in formula (A-1-1). a1 and R a2 In particular, X c is preferably an acyl group, more preferably a formyl group.

[0085] In formula (A-3), a c represents an integer of 0 to 3, and is preferably 0 or 1.

[0086] Specific examples of the resin represented by formula (A-3) include the following resins.

[0087] [ka]

[0088] The resin represented by formula (A-3) can be produced, for example, by the method described in Japanese Patent No. 5776717.

[0089] Furthermore, among the (A) furan type curable resins, a furan type curable resin in which the furan skeleton can react to form a bond is preferred. Therefore, the (A) furan type curable resin preferably contains a furan type curable resin in which the furan skeleton can react to form a bond, and may contain only a furan type curable resin in which the furan skeleton can react to form a bond. The furan skeleton can usually form a bond by a Diels-Alder reaction. Such a Diels-Alder reaction does not usually generate a polar group. Therefore, the polarity of the insulating layer can be reduced, and therefore the dielectric tangent of the insulating layer can be reduced.

[0090] A preferred example of a furan-type curable resin in which the furan skeleton can react to form a bond is a resin represented by the following formula (A-4).

[0091] [ka]

[0092] (In formula (A-4), R d1 Each of a may have a substituent independently. d + represents a monovalent aliphatic group; X d1 each independently represents a hydrogen atom or a substituent; X d2 each independently represents a substituent; d each independently represents 1 or 2; b d each independently represents an integer of 0 to 3; d represents an integer from 1 to 4.)

[0093] In formula (A-4), R d1 Each of a may have a substituent independently. d It represents a +1-valent aliphatic group. d represents an integer of 1 or 2, so R d1 may be a divalent or trivalent aliphatic group which may have a substituent.

[0094] R d1 The divalent aliphatic group which may have a substituent is represented by L in formula (A-1-1).a11 It may be the same as the divalent aliphatic group which may have the substituents described as an example. Among them, R d1 When is a divalent aliphatic group, the R d1 is preferably an alkylene group, and more preferably an alkylene group having 3 to 12 carbon atoms.

[0095] R d1 In the trivalent aliphatic group which may have the substituents of, the trivalent aliphatic group may be a chain aliphatic group or a cyclic aliphatic group. The number of carbon atoms of the trivalent chain aliphatic group is preferably 1 to 12, more preferably 1 to 6, and even more preferably 1 to 4. On the other hand, the number of carbon atoms of the trivalent cyclic aliphatic group is preferably 3 to 15, more preferably 3 to 12, and even more preferably 3 to 10. The number of carbon atoms of the substituents is not included in the number of carbon atoms. The trivalent chain aliphatic group may be a saturated chain aliphatic group or an unsaturated chain aliphatic group. Further, the trivalent cyclic aliphatic group may be a monocyclic cyclic aliphatic group or a polycyclic cyclic aliphatic group. Also, R d1 Examples of the substituents in the trivalent aliphatic group which may have the substituents of include the same examples as the substituents in the divalent aliphatic group which may have the substituents of L in the formula (A-1-1). Among them, R a11 When is a trivalent aliphatic group, the R d1 is preferably an aliphatic group having 1 carbon atom (that is, a group obtained by removing 3 hydrogen atoms from methane). d1

[0096] In the formula (A-4), X d1 each independently represents a hydrogen atom or a substituent. When X d1 is a substituent, the substituent may be the same as the substituents in the monovalent aromatic group which may have the substituents of R a1 and R a2 in the formula (A-1-1). Among them, X d1 is preferably a hydrogen atom or an alkyl group, and more preferably a hydrogen atom or a methyl group.

[0097] In the formula (A-4), X d2Each of X independently represents a substituent. d2 is R in formula (A-1-1). a1 and R a2 In particular, X d2 is preferably an alkyl group or a hydroxyalkyl group, more preferably a methyl group or a hydroxymethyl group.

[0098] In formula (A-4), a d each independently represents 1 or 2.

[0099] In formula (A-4), b d each independently represents an integer of 0 to 3, and preferably 0 to 2.

[0100] In formula (A-4), c d represents an integer from 1 to 4.

[0101] Specific examples of the resin represented by formula (A-4) include the following resins. d2 represents an alkylene group having one or more carbon atoms.

[0102] [ka]

[0103] The resin represented by formula (A-4) is commercially available. For example, commercially available products of the resin represented by formula (A-4) include "BioPrepolymer (registered trademark) 1552L" (resin represented by formula (d-1)) manufactured by Daiei Sangyo Co., Ltd.

[0104] Another preferred example of a furan-type curable resin in which the furan skeleton can react to form a bond is a resin containing a structural unit represented by the following formula (A-5).

[0105] [ka]

[0106] (In formula (A-5), R e1 represents a hydrogen atom, an alkyl group which may have an alkoxy group, a cycloalkyl group which may have an alkoxy group, an acyl group which may have an alkoxy group, an aralkyl group which may have an alkoxy group, a silyl group, or a group derived from a monovalent polyethylene glycol or a derivative thereof.

[0107] In formula (A-5), R e1 represents a hydrogen atom, an alkyl group which may have an alkoxy group, a cycloalkyl group which may have an alkoxy group, an acyl group which may have an alkoxy group, an aralkyl group which may have an alkoxy group, a silyl group, or a group derived from monovalent polyethylene glycol or a derivative thereof. The term "a group derived from monovalent polyethylene glycol or a derivative thereof" refers to a group obtained by removing one hydrogen atom from monovalent polyethylene glycol or a derivative thereof. Among these, R e1 is preferably a hydrogen atom or an alkyl group which may have an alkoxy group, more preferably an alkyl group not having a hydrogen atom or an alkoxy group, further preferably an alkyl group having 1 to 5 carbon atoms, and particularly preferably a methyl group.

[0108] Specific examples of the resin represented by formula (A-5) include resins having the following structure: e represents the number of repeating structural units and is an integer of 1 or more.

[0109] [ka]

[0110] The resin represented by formula (A-5) can be produced, for example, by the method described in JP-A-2010-43203.

[0111] Yet another preferred example of a furan-type curable resin in which the furan skeleton can react to form a bond is a resin containing a structural unit represented by the following formula (A-6).

[0112] [ka]

[0113] (In formula (A-6), R f1 and R f2 each independently represents a hydrogen atom, an optionally substituted hydrocarbon group, or an optionally substituted hydrocarbonoxy group; R f1 When R is an optionally substituted hydrocarbon group or an optionally substituted hydrocarbonoxy group, two R f1 may be bonded to each other via a direct bond or a linking group to form a ring; R f3 each independently represents a hydrocarbon group having from 1 to 20 carbon atoms which may be substituted, or a hydrocarbonoxy group having from 1 to 20 carbon atoms which may be substituted; Y f1 are each independently -CH 2 -, -CHR f4 -, -C(R f4 ) 2 -, -PR f4 -, -S-, -O-, -Si(R f4 ) 2 -, -NR f4 - or -C=C-; R f4 each independently represents a hydrocarbon group having 1 to 8 carbon atoms; f represents an integer between 0 and 256; f represents an integer between 0 and 128; f +2b f is an integer between 2 and 256 inclusive.)

[0114] In formula (A-6), R f1 and R f2R each independently represents a hydrogen atom, a hydrocarbon group which may have a substituent, or a hydrocarbonoxy group which may have a substituent. f1 and R f2 The hydrocarbon group (including the hydrocarbon group contained in the hydrocarbonoxy group) may be an aliphatic hydrocarbon group or an aromatic hydrocarbon group. The aliphatic hydrocarbon group is preferably a saturated aliphatic hydrocarbon group. f1 and R f2 The number of carbon atoms in the hydrocarbon group is usually 1 or more and 20 or less. f1 and R f2 When the hydrocarbon group of R is an aliphatic hydrocarbon group, the number of carbon atoms in the aliphatic hydrocarbon group is usually 1 or more and usually 20 or less, preferably 12 or less, more preferably 8 or less, and further preferably 4 or less. f1 and R f2 When the hydrocarbon group is an aromatic hydrocarbon group, the aromatic hydrocarbon group usually has 3 or more, preferably 6 or more, and usually has 20 or less, preferably 16 or less, more preferably 12 or less, carbon atoms.

[0115] R f1 and R f2 Examples of the substituents in the optionally substituted hydrocarbon group and the optionally substituted hydrocarbonoxy group include R a1 and R a2 The same examples of the substituents as those of the monovalent aromatic group which may have a substituent are mentioned.

[0116] R f1 When R is an optionally substituted hydrocarbon group or an optionally substituted hydrocarbonoxy group, two R f1 may be bonded to each other via a direct bond or a linking group to form a ring. Examples of the linking group include -S-, -O-, -CO-, -COO-, -OCO-, -COS-, -SCO-, -CONR f5 -, -NR f5 CO-, -OCONR f5 -, -SO 2-, -C=C-, -C=N-, -N=C-, -N=N-, -Si(R f5 ) 2 - etc. (R f5 each independently represents a hydrocarbon group having 1 to 8 carbon atoms.

[0117] Among the above, R f1 and R f2 is preferably a hydrogen atom.

[0118] In formula (A-6), R f3 R each independently represents a hydrocarbon group which may have a substituent, or a hydrocarbonoxy group which may have a substituent. f3 The optionally substituted hydrocarbon group and the optionally substituted hydrocarbonoxy group represented by the following formula (I) are each represented by R f1 and R f2 In particular, R f3 is preferably a hydrocarbon group which may have a substituent, more preferably a hydrocarbon group which has no substituent, further preferably a saturated aliphatic hydrocarbon group, further preferably an alkyl group, and particularly preferably a methyl group. f3 may be different, but are preferably the same group.

[0119] In formula (A-6), Y f1 are each independently -CH 2 -, -CHR f4 -, -C(R f4 ) 2 -, -PR f4 -, -S-, -O-, -Si(R f4 ) 2 -, -NR f4 - or -C=C-. R f4 each independently represents a hydrocarbon group having 1 to 8 carbon atoms.

[0120] In formula (A-6), a frepresents an integer of 0 or more and 256 or less, preferably an integer of 0 or more and 16 or less, more preferably an integer of 2 or more and 8 or less, and even more preferably 2, 4, or 8.

[0121] In formula (A-6), b f represents an integer of 0 or more and 128 or less, preferably an integer of 0 or more and 8 or less, more preferably 0, 2, or 4, and even more preferably 0.

[0122] However, a f +2b f is an integer of 2 or more and 256 or less, preferably an integer of 2 or more and 16 or less, more preferably an integer of 2 or more and 8 or less, even more preferably 2, 4, or 8, and particularly preferably 4 or 8.

[0123] Furthermore, a contained in formula (A-6) f Units and b f The arrangement of the units is not particularly limited, and they may be arranged randomly or alternately, or the same structures may be bonded consecutively.

[0124] The resin containing the structural unit represented by formula (A-6) may contain an arbitrary structural unit in combination with the structural unit represented by formula (A-6). Examples of the arbitrary structural unit include a structural unit derived from a diene compound and a structural unit derived from a diyne compound. The structural unit derived from a diene compound represents a structural unit having a structure obtained by polymerizing a diene compound. The diene compound is a compound having two carbon-carbon double bonds in one molecule, and examples thereof include a hydrocarbon compound having two carbon-carbon double bonds and a compound having a structure in which an oxygen atom is interposed between the carbon-carbon bonds of the hydrocarbon compound. The structural unit derived from a diyne compound represents a structural unit having a structure obtained by polymerizing a diyne compound. The diyne compound is a compound having two carbon-carbon triple bonds in one molecule, and examples thereof include a hydrocarbon compound having two carbon-carbon triple bonds and a compound having an oxygen atom interposed between the carbon-carbon bonds of the hydrocarbon compound. Therefore, the structural unit derived from a diene compound and the structural unit derived from a diyne compound may be, for example, a hydrocarbon group, or a hydrocarbon group in which an oxygen atom may be interposed between the carbon-carbon bonds. Specific examples of the arbitrary structural unit include a divalent hydrocarbon group having 1 to 20 carbon atoms (e.g., an alkylene group) and a group in which an oxygen atom is interposed between the carbon-carbon bonds of the divalent hydrocarbon group.

[0125] Specific examples of the resin represented by formula (A-6) include resins containing the following structure: f represents the number of repeating structural units and is an integer of 1 or more.

[0126] [ka]

[0127] The resin represented by formula (A-6) can be produced, for example, by the method described in WO 2023 / 100914.

[0128] As yet another example of a preferred furan-type curable resin in which the furan skeleton can react to form a bond, there may be mentioned dimethyl 3,3'-dihexyl-5,5'-dimethoxy-2,2'-bifuran-4,4'-dicarboxylate, and the like.

[0129] (A) The furan-type curable resin may be used alone or in combination of two or more.

[0130] (A) The number average molecular weight of the furan-type curable resin is preferably 100 or more, more preferably 500 or more, still more preferably 1,000 or more, and preferably 1,000,000 or less, more preferably 500,000 or less, still more preferably 100,000 or less, and may be 10,000 or less, 5,000 or less, or 3,000 or less. The number average molecular weight can be measured as a polystyrene-equivalent value by gel permeation chromatography (GPC).

[0131] (A) When the furan-type curable resin contains an active group other than the furan skeleton, the range of the active group equivalent of the (A) furan-type curable resin is preferably 100 g / eq. or more, more preferably 120 g / eq. or more, still more preferably 130 g / eq. or more, and preferably 500,000 g / eq. or less, more preferably 250,000 g / eq. or less, still more preferably 50,000 g / eq. or less, and may be 5,000 or less, 2,500 or less, or 1,500 or less. For example, when the (A) furan-type curable resin contains an active ester group as the active group, it is preferable that the (A) furan-type curable resin has an active group equivalent within the above range. The active group equivalent represents the mass of the resin containing 1 equivalent of the active group.

[0132] The (A) furan-type curable resin is preferably produced using a raw material derived from a plant. A resin containing a furan skeleton can be synthesized by deriving from biomass such as glucose derived from a plant, cellulose derived from a plant, or fructose derived from a plant. For example, a raw material compound having reactive groups at the 2-position and 5-position of a furan skeleton, such as 5-hydroxymethylfurfural or 2,5-furandicarboxylic acid, can be synthesized by deriving from biomass. Therefore, a resin having groups other than hydrogen atoms bonded to the 2-position and 5-position of a furan skeleton can be produced from these raw material compounds and used for the (A) furan-type curable resin. The use of the (A) furan-type curable resin produced from biomass in this way can contribute to energy saving, cost saving, and sustainability.

[0133] The degree of use of biomass can be expressed by the biomass ratio. (A) The biomass ratio of the furan-type curable resin is preferably large, specifically, preferably 10% by mass or more, more preferably 15% by mass or more, and even more preferably 20% by mass or more. The upper limit is preferably 100% by mass or less.

[0134] The Japan Organic Resources Association defines "biomass" as any organic resource derived from renewable living organisms, excluding fossil resources (however, it does include inorganic resources such as shells that are produced directly by living organisms). Based on this definition, the biomass ratio of a material can be calculated as the ratio of the mass of the biologically derived components in the material to the mass of the material. Therefore, the biomass ratio of resin can be calculated using the following formula (M1). Biomass ratio (mass%) = (mass of biological components in resin / mass of resin) x 100 (M1) However, even if the material contains ingredients that have been certified using the mass balance method, the mass balance method will not be used and the biomass ratio will be calculated based on formula (M1) above.

[0135] The range of the amount of the (A) furan type curable resin in the resin composition layer is usually 2% by mass or more, preferably 2.5% by mass or more, and more preferably 3% by mass or more, based on 100% by mass of the total amount of the resin composition layer. When the resin composition layer contains the (A) furan type curable resin in the above range, unevenness has been formed as a problem to be solved in this embodiment. In this embodiment, it is possible to eliminate this unevenness. In particular, when a furan type curable resin having a high biomass ratio is used as the (A) furan type curable resin, the biomass ratio of the resin composition layer can be increased by using a large amount of the (A) furan type curable resin. The upper limit of the amount of the (A) furan type curable resin is preferably 40% by mass or less, more preferably 30% by mass or less, and even more preferably 20% by mass or less, from the viewpoint of obtaining an insulating layer having excellent properties such as a linear thermal expansion coefficient using a sufficient amount of the (C) inorganic filler.

[0136] The range of the amount of the (A) furan type curable resin in the resin composition layer is preferably 2% by mass or more, more preferably 2.5% by mass or more, and even more preferably 3% by mass or more, based on 100% by mass of the nonvolatile components in the resin composition layer, and is preferably 50% by mass or less, more preferably 40% by mass or less, even more preferably 30% by mass or less, and even more preferably 20% by mass or less. Unless otherwise specified, the nonvolatile components in the resin composition layer refer to components other than the solvent in the resin composition layer. When the amount of the (A) furan type curable resin is within the above range, there has been a tendency for unevenness to be easily formed in the insulating layer in the past, but this embodiment can suppress this unevenness. In addition, when a furan type curable resin with a large biomass ratio is used as the (A) furan type curable resin, the biomass ratio of the resin composition layer can be increased. Furthermore, the linear thermal expansion coefficient, dielectric tangent, and glass transition temperature of the insulating layer can usually be improved.

[0137] The range of the amount of the (A) furan type curable resin in the resin composition layer is preferably 3% by mass or more, more preferably 5% by mass or more, particularly preferably 10% by mass or more, and preferably 80% by mass or less, more preferably 70% by mass or less, even more preferably 60% by mass or less, particularly preferably 40% by mass or less, based on 100% by mass of the resin components in the resin composition layer. Unless otherwise specified, the resin components in the resin composition layer refer to the non-volatile components in the resin composition layer excluding the (C) inorganic filler. When the amount of the (A) furan type curable resin is within the above range, there has been a tendency for unevenness to be formed in the insulating layer in the past, but this embodiment can suppress this unevenness. In addition, when a furan type curable resin with a large biomass ratio is used as the (A) furan type curable resin, the biomass ratio of the resin composition layer can be increased. Furthermore, the linear thermal expansion coefficient, dielectric tangent, and glass transition temperature of the insulating layer can usually be improved.

[0138] <(B) Tetrahydrofuran> The resin composition layer of the resin sheet contains tetrahydrofuran (B) as component (B). Tetrahydrofuran (B) is a component that can function as a solvent in the process of forming the resin composition layer, and is usually contained in the resin composition layer in a state where it is compatible with resin components such as the furan-type curable resin (A).

[0139] The range of the amount of (B) tetrahydrofuran in the resin composition layer is usually 0.10% by mass or more, preferably 0.12% by mass or more, and more preferably 0.14% by mass or more, based on the total amount of the resin composition layer (100% by mass). When the resin composition layer contains such an amount of (B) tetrahydrofuran, unevenness of the insulating layer can be suppressed. The upper limit is preferably 5% by mass or less, more preferably 3% by mass or less, and even more preferably 2% by mass or less.

[0140] The amount of (B) tetrahydrofuran in the resin composition layer can be analyzed and calculated by GC-MS (gas chromatography mass spectrometry).

[0141] The amount of (B) tetrahydrofuran in the resin composition layer can be adjusted, for example, by adjusting the amount of (B) tetrahydrofuran blended in the resin varnish, or by adjusting the drying conditions of the resin varnish in the production process of the resin sheet.

[0142] The amount of (B) tetrahydrofuran in the resin composition layer is preferably 2 mass% or more, more preferably 5 mass% or more, and even more preferably 8 mass% or more, relative to 100 mass% of all solvents in the resin composition layer, and is usually 100 mass% or less, preferably 80 mass% or less, and more preferably 60 mass% or less.

[0143] The amount of the solvent in the resin composition layer can be calculated by analysis using a GC-MS method.

[0144] The range of the amount of (B) tetrahydrofuran in the resin composition layer is preferably 0.5 mass% or more, more preferably 1 mass% or more, and even more preferably 1.5 mass% or more, relative to 100 mass% of (A) furan-type curable resin in the resin composition layer, and is preferably 50 mass% or less, more preferably 40 mass% or less, and even more preferably 30 mass% or less.

[0145] <(C) Inorganic filler> The resin composition layer of the resin sheet contains an inorganic filler (C) as a component (C). The inorganic filler (C) is a particle of an inorganic material. Thus, the inorganic filler (C) is contained in the resin composition layer in a particulate state, and is usually contained in the insulating layer while maintaining the particulate state. The inorganic filler (C) can reduce the linear thermal expansion coefficient of the insulating layer, thereby reducing warping of the circuit board.

[0146] The range of the amount of the inorganic filler (C) in the resin composition layer is usually 50% by mass or more, preferably 55% by mass or more, more preferably 60% by mass or more, and preferably 90% by mass or less, more preferably 85% by mass or less, and even more preferably 80% by mass or less, based on 100% by mass of the non-volatile components in the resin composition layer. When the resin composition layer contains the inorganic filler (C) in an amount within the above range, unevenness has been formed in the past as a problem to be solved in this embodiment. In this embodiment, it is possible to eliminate this unevenness. In addition, the resin composition layer containing the inorganic filler (C) in an amount within the above range can form an insulating layer with a small linear thermal expansion coefficient, and can usually improve the dielectric loss tangent and glass transition temperature of the insulating layer.

[0147] As the inorganic material forming the (C) inorganic filler, an inorganic compound is usually used. Examples of the material for the (C) inorganic filler include silica, alumina, glass, cordierite, silicon oxide, barium sulfate, barium carbonate, talc, clay, mica powder, zinc oxide, hydrotalcite, boehmite, aluminum hydroxide, magnesium hydroxide, calcium carbonate, magnesium carbonate, magnesium oxide, boron nitride, aluminum nitride, manganese nitride, aluminum borate, strontium carbonate, strontium titanate, calcium titanate, magnesium titanate, bismuth titanate, titanium oxide, zirconium oxide, barium titanate, barium zirconate titanate, barium zirconate, calcium zirconate, zirconium phosphate, and zirconium tungstate phosphate. Among these, silica and alumina are preferred, and silica is particularly preferred. Therefore, the (C) inorganic filler preferably contains silica, and may contain only silica. Examples of silica include amorphous silica, fused silica, crystalline silica, synthetic silica, and hollow silica. The silica is preferably spherical silica.The inorganic filler (C) may be used alone or in combination of two or more kinds.

[0148] (C) As commercially available inorganic fillers, for example, "SP60-05", "SP507-05" manufactured by Nippon Steel Chemical & Material Co., Ltd.; "YC100C", "YA050C", "YA050C-MJE", "YA010C", "SC2500SQ", "SO-C4", "SO-C2", "SO-C1" manufactured by Admatechs Co., Ltd.; "UFP-30", "DAW-03", "FB-105FD" manufactured by Denka Co., Ltd.; "Silfill NSS-3N", "Silfill NSS-4N", "Silfill NSS-5N" manufactured by Tokuyama Corporation; "Celsfiers", "MGH-005" manufactured by Taiheiyo Cement Corporation; "Esferic", "BA-1" manufactured by JGC Catalysts & Chemicals Ltd. etc. can be mentioned.

[0149] (C) The average particle size of the inorganic filler is preferably 0.01 μm or more, more preferably 0.05 μm or more, still more preferably 0.1 μm or more, and preferably 10 μm or less, more preferably 5 μm or less, still more preferably 3 μm or less, and still more preferably 1 μm or less.

[0150] (C) The average particle size of the inorganic filler can be measured by the laser diffraction / scattering method based on the Mie scattering theory. Specifically, it can be measured by creating a volume-based particle size distribution of the inorganic filler with a laser diffraction / scattering type particle size distribution measuring device and taking the median diameter thereof as the average particle size. As the measurement sample, 100 mg of the inorganic filler and 10 g of methyl ethyl ketone can be weighed into a vial and dispersed by ultrasonic waves for 10 minutes. The measurement sample can be used to measure the volume-based particle size distribution of the inorganic filler using a laser diffraction type particle size distribution measuring device with the wavelengths of the light sources used being blue and red and in a flow cell method, and the average particle size can be calculated as the median diameter from the obtained particle size distribution. Examples of the laser diffraction type particle size distribution measuring device include "LA-960" manufactured by Horiba, Ltd.

[0151] (C) The specific surface area of the inorganic filler is preferably 0.1 m 2 / g or more, more preferably 0.5 m 2 / g or more, still more preferably 1 m 2 / g or more, particularly preferably 3 m 2 / g or more, preferably 100m 2 / g or less, more preferably 70m 2 / g or less, more preferably 50m 2 / g or less, particularly preferably 40m 2 The specific surface area of ​​the inorganic filler can be measured by adsorbing nitrogen gas onto the surface of a sample using a specific surface area measuring device (Macsorb HM-1210 manufactured by Mountech Co., Ltd.) according to the BET method, and calculating the specific surface area using the BET multipoint method.

[0152] (C) The inorganic filler is preferably treated with a surface treatment agent from the viewpoint of improving moisture resistance and dispersibility. Examples of the surface treatment agent include fluorine-containing silane coupling agents, aminosilane coupling agents, epoxysilane coupling agents, mercaptosilane coupling agents, silane coupling agents, alkoxysilanes, organosilazane compounds, titanate coupling agents, etc. The surface treatment agent may be used alone or in any combination of two or more.

[0153] Examples of commercially available surface treatment agents include Shin-Etsu Chemical Co., Ltd.'s "KBM403" (3-glycidoxypropyltrimethoxysilane), Shin-Etsu Chemical Co., Ltd.'s "KBM803" (3-mercaptopropyltrimethoxysilane), Shin-Etsu Chemical Co., Ltd.'s "KBE903" (3-aminopropyltriethoxysilane), Shin-Etsu Chemical Co., Ltd.'s "KBM573" (N-phenyl-3-aminopropyltrimethoxysilane), Shin-Etsu Chemical Co., Ltd.'s "SZ-31" (hexamethyldisilazane), Shin-Etsu Chemical Co., Ltd.'s "KBM103" (phenyltrimethoxysilane), Shin-Etsu Chemical Co., Ltd.'s "KBM-4803" (long-chain epoxy-type silane coupling agent), and Shin-Etsu Chemical Co., Ltd.'s "KBM-7103" (3,3,3-trifluoropropyltrimethoxysilane).

[0154] From the viewpoint of improving the dispersibility of the inorganic filler, the degree of surface treatment with the surface treatment agent is preferably within a specific range. Specifically, 100% by mass of the inorganic filler is preferably surface-treated with 0.2% to 5% by mass of the surface treatment agent, more preferably with 0.2% to 3% by mass of the surface treatment agent, and even more preferably with 0.3% to 2% by mass of the surface treatment agent.

[0155] The degree of surface treatment with the surface treatment agent can be evaluated by the amount of carbon per unit surface area of ​​the inorganic filler. From the viewpoint of improving the dispersibility of the inorganic filler, the amount of carbon per unit surface area of ​​the inorganic filler is set to 0.02 mg / m 2 More than 0.1 mg / m is preferable. 2 More preferably, 0.2 mg / m or more 2 On the other hand, from the viewpoint of preventing an increase in the melt viscosity of the resin composition layer, it is more preferable that the melt viscosity is 1.0 mg / m 2 Less than 0.8 mg / m is preferred. 2 Less than 0.5 mg / m is more preferable. 2 The following is even more preferred:

[0156] (C) The amount of carbon per unit surface area of ​​the inorganic filler can be measured after the surface-treated inorganic filler is washed with a solvent (e.g., methyl ethyl ketone (MEK)). Specifically, a sufficient amount of MEK as a solvent is added to the inorganic filler that has been surface-treated with a surface treatment agent, and ultrasonic cleaning is performed at 25°C for 5 minutes. After removing the supernatant and drying the solid content, the amount of carbon per unit surface area of ​​the inorganic filler can be measured using a carbon analyzer. As the carbon analyzer, the "EMIA-320V" manufactured by Horiba, Ltd., or the like can be used.

[0157] The range of the total amount of (A) the furan type curable resin and (C) the inorganic filler in the resin composition layer is, relative to 100 mass% of the non-volatile components in the resin composition layer, preferably 52 mass% or more, more preferably 53 mass% or more, even more preferably 54 mass% or more, and is preferably 95 mass% or less, more preferably 90 mass% or less, even more preferably 86 mass% or less.

[0158] The range of the total amount of (A) the furan-type curable resin, (B) tetrahydrofuran, and (C) the inorganic filler in the resin composition layer is, relative to 100% by mass of the total amount of the resin composition layer, preferably 53% by mass or more, more preferably 55% by mass or more, and even more preferably 57% by mass or more, and is preferably 99% by mass or less, more preferably 95% by mass or less, and even more preferably 90% by mass or less.

[0159] <(D) Any hardening resin> The resin composition layer of the resin sheet may contain, as an optional component, an optional curable resin (D) other than the furan-type curable resin (A). The optional curable resin (D) as the component (D) does not include those corresponding to the above-mentioned components (A) to (C). The optional curable resin (D) as the component (D) may be a thermosetting resin, a photocurable resin, or a combination thereof. Among them, the optional curable resin (D) preferably contains a thermosetting resin, and may contain only a thermosetting resin. The optional curable resin (D) may be used alone or in combination of two or more types.

[0160] Examples of the optional curable resin (D) include epoxy resins, phenolic resins, active ester resins, carbodiimide resins, cyanate resins, acid anhydride resins, amine resins, benzoxazine resins, thiol resins, and radical polymerizable resins. Among these, epoxy resins are preferred. Hereinafter, epoxy resins classified as the optional curable resin (D) may be referred to as "(D-1) epoxy resins".

[0161] The epoxy resin (D-1) is a curable resin having an epoxy group. When the furan-type curable resin (A) contains an active group such as an active ester group that can react with an epoxy group, the epoxy resin (D-1) can react with the furan-type curable resin (A) to form a bond.

[0162] (D-1) Examples of the epoxy resin include bixylenol type epoxy resin, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, bisphenol AF type epoxy resin, dicyclopentadiene type epoxy resin, trisphenol type epoxy resin, naphthol novolac type epoxy resin, phenol novolac 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 Examples of the epoxy resin include ester type epoxy resin, cresol novolac type epoxy resin, phenol aralkyl type epoxy resin, biphenyl type epoxy resin, linear aliphatic epoxy resin, epoxy resin having a butadiene structure, alicyclic epoxy resin, heterocyclic epoxy resin, spiro ring-containing epoxy resin, cyclohexane type epoxy resin, cyclohexane dimethanol type epoxy resin, naphthylene ether type epoxy resin, trimethylol type epoxy resin, tetraphenylethane type epoxy resin, isocyanurate type epoxy resin, phenolphthalimidine type epoxy resin, etc. The epoxy resin (D-1) may be used alone or in combination of two or more kinds.

[0163] From the viewpoint of obtaining an insulating layer having excellent heat resistance, the epoxy resin (D-1) preferably contains an epoxy resin containing an aromatic structure. The 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 bixylenol type epoxy resins, bisphenol A type epoxy resins, bisphenol F type epoxy resins, bisphenol S type epoxy resins, bisphenol AF type epoxy resins, dicyclopentadiene type epoxy resins, trisphenol type epoxy resins, naphthol novolac type epoxy resins, phenol novolac type epoxy resins, tert-butyl-catechol type epoxy resins, naphthalene type epoxy resins, naphthol type epoxy resins, anthracene type epoxy resins, bixylenol type epoxy resins, and glycidylamines having an aromatic structure. type epoxy resins, glycidyl ester type epoxy resins having an aromatic structure, cresol novolac type epoxy resins, biphenyl type epoxy resins, linear aliphatic epoxy resins having an aromatic structure, epoxy resins having a butadiene structure having an aromatic structure, alicyclic epoxy resins having an aromatic structure, heterocyclic epoxy resins, spiro ring-containing epoxy resins having an aromatic structure, cyclohexane dimethanol type epoxy resins having an aromatic structure, naphthylene ether type epoxy resins, trimethylol type epoxy resins having an aromatic structure, and tetraphenylethane type epoxy resins having an aromatic structure.

[0164] The epoxy resin (D-1) preferably contains 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 particularly preferably 70% by mass or more, based on 100% by mass of the non-volatile components of the epoxy resin.

[0165] Generally, epoxy resins are classified into epoxy resins that are liquid at a temperature of 20° C. (hereinafter sometimes referred to as "liquid epoxy resins") and epoxy resins that are solid at a temperature of 20° C. (hereinafter sometimes referred to as "solid epoxy resins") The (D-1) epoxy resin may contain only a liquid epoxy resin, or may contain only a solid epoxy resin, or may contain a combination of a liquid epoxy resin and a solid epoxy resin.

[0166] The liquid epoxy resin is preferably a liquid epoxy resin having two or more epoxy groups in one molecule.

[0167] As the liquid epoxy resin, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol AF type epoxy resin, naphthalene type epoxy resin, glycidyl ester type epoxy resin, glycidyl amine type epoxy resin, phenol novolac type epoxy resin, alicyclic epoxy resin having an ester skeleton, cyclohexane type epoxy resin, cyclohexane dimethanol type epoxy resin, and epoxy resin having a butadiene structure are preferred.

[0168] Specific examples of liquid epoxy resins include "HP4032", "HP4032D", and "HP4032SS" (naphthalene type epoxy resins) manufactured by DIC Corporation; "828US", "828EL", "jER828EL", "825", and "Epicoat 828EL" (bisphenol A type epoxy resins) manufactured by Mitsubishi Chemical Corporation; "jER807" and "1750" (bisphenol F type epoxy resins) manufactured by Mitsubishi Chemical Corporation; "jER152" (phenol novolac type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "630", "630LSD", and "604" (glycidylamine type epoxy resins) manufactured by Mitsubishi Chemical Corporation; "ED-523T" (glycirol type epoxy resin) manufactured by ADEKA Corporation; "EP-3950L" and "EP-3980S" (glycidylamine type epoxy resins) manufactured by ADEKA Corporation; Examples of such epoxy resins include "EP-4088S" (dicyclopentadiene type epoxy resin) manufactured by Company A; "ZX1059" (mixture of bisphenol A type epoxy resin and bisphenol F type epoxy resin) manufactured by Nippon Steel Chemical & Material Co., Ltd.; "YD-8125G" (bisphenol A type epoxy resin) manufactured by Nippon Steel Chemical & Material Co., Ltd.; "EX-721" (glycidyl ester type epoxy resin) manufactured by Nagase Chemtex Corporation; "Celloxide 2021P" (alicyclic epoxy resin having an ester skeleton) manufactured by Daicel Corporation; "PB-3600" manufactured by Daicel Corporation, "JP-100" and "JP-200" (epoxy resin having a butadiene structure) manufactured by Nippon Soda Co., Ltd.; "ZX1658" and "ZX1658GS" (liquid 1,4-glycidylcyclohexane type epoxy resin) manufactured by Nippon Steel Chemical & Material Co., Ltd. These may be used alone or in combination of two or more types.

[0169] As the solid epoxy resin, a solid epoxy resin having three or more epoxy groups in one molecule is preferable, and an aromatic solid epoxy resin having three or more epoxy groups in one molecule is more preferable.

[0170] Examples of the solid epoxy resin include a bicyclol type epoxy resin, a naphthalene type epoxy resin, a naphthalene type tetrafunctional epoxy resin, a naphthol novolak type epoxy resin, a cresol novolak type epoxy resin, a dicyclopentadiene type epoxy resin, a trisphenol type epoxy resin, a naphthol type epoxy resin, a biphenyl type epoxy resin, a naphthylene ether type epoxy resin, an anthracene type epoxy resin, a bisphenol A type epoxy resin, a bisphenol AF type epoxy resin, a phenol aralkyl type epoxy resin, a tetraphenylethane type epoxy resin, and a phenolphthalimide type epoxy resin.

[0171] Specific examples of solid epoxy resins include "HP4032H" (naphthalene type epoxy resin) manufactured by DIC Corporation; "HP-4700" and "HP-4710" (naphthalene type tetrafunctional epoxy resins) manufactured by DIC Corporation; "N-690" (cresol novolac type epoxy resin) manufactured by DIC Corporation; "N-695" (cresol novolac type epoxy resin) manufactured by DIC Corporation; "HP-7200", "HP-7200HH", "HP-7200H", and "HP-7200L" (dicyclopentadiene type epoxy resins) manufactured by DIC Corporation; "EXA-7311" and "E XA-7311-G3, EXA-7311-G4, EXA-7311-G4S, HP6000, HP-6000L (naphthylene ether type epoxy resin); EPPN-502H (trisphenol type epoxy resin) manufactured by Nippon Kayaku; NC7000L (naphthol novolac type epoxy resin) manufactured by Nippon Kayaku; NC3000H, NC3000, NC3000L, NC3000FH, NC3100 (biphenyl type epoxy resin) manufactured by Nippon Steel Chemical & Material; ESN475V manufactured by Nippon Steel Chemical & Material. , "ESN4100V" (naphthalene type epoxy resin); "ESN485" (naphthol type epoxy resin) manufactured by Nippon Steel Chemical & Material Co., Ltd.; "ESN375" (dihydroxynaphthalene type epoxy resin) manufactured by Nippon Steel Chemical & Material Co., Ltd.; "YX4000H", "YX4000", "YX4000HK", "YL7890" (bixylenol type epoxy resin) manufactured by Mitsubishi Chemical Co., Ltd.; "YL6121" (biphenyl type epoxy resin) manufactured by Mitsubishi Chemical Co., Ltd.; "YX8800" (anthracene type epoxy resin) manufactured by Mitsubishi Chemical Co., Ltd. Examples of epoxy resins that can be used include "YX7700" (phenol aralkyl type epoxy resin) manufactured by Osaka Gas Chemicals; "PG-100" and "CG-500" manufactured by Osaka Gas Chemicals; "YX7760" (bisphenol AF type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "YL7800" (fluorene type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "jER1010" (bisphenol A type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "jER1031S" (tetraphenylethane type epoxy resin) manufactured by Mitsubishi Chemical Corporation; and "WHR991S" (phenolphthalimidine type epoxy resin) manufactured by Nippon Kayaku Co., Ltd.These may be used alone or in combination of two or more.

[0172] When the epoxy resin (D-1) contains a combination of a liquid epoxy resin and a solid epoxy resin, the mass ratio thereof (liquid epoxy resin:solid epoxy resin) is preferably 20:1 to 1:20, more preferably 10:1 to 1:10, and particularly preferably 7:1 to 1:7.

[0173] The epoxy equivalent of the (D-1) epoxy resin is preferably in the range of 50 g / eq. to 5,000 g / eq., more preferably 60 g / eq. to 3,000 g / eq., further preferably 80 g / eq. to 2,000 g / eq., and particularly preferably 110 g / eq. to 1,000 g / eq. The epoxy equivalent represents the mass of the resin per equivalent of epoxy group. The epoxy equivalent can be measured according to JIS K7236.

[0174] The weight average molecular weight (Mw) of the epoxy resin (D-1) is preferably in the range of 100 to 5,000, more preferably 250 to 3,000, and further preferably 400 to 1,500. The weight average molecular weight of the resin can be measured by gel permeation chromatography (GPC) as a polystyrene-equivalent value.

[0175] The range of the amount of the (D-1) epoxy resin in the resin composition layer is preferably 1 mass% or more, more preferably 5 mass% or more, and even more preferably 10 mass% or more, relative to 100 mass% of the non-volatile components in the resin composition layer, and is preferably 45 mass% or less, more preferably 40 mass% or less, and even more preferably 35 mass% or less.

[0176] The range of the amount of the (D-1) epoxy resin in the resin composition layer is, relative to 100% by mass of the resin components in the resin composition layer, preferably 10% by mass or more, more preferably 20% by mass or more, even more preferably 40% by mass or more, and is preferably 90% by mass or less, more preferably 80% by mass or less, even more preferably 70% by mass or less.

[0177] In the case of the (D-1) epoxy resin, the (D-1) epoxy resin may react with itself, and the (D-1) epoxy resin may react with the curing agent. Examples of the curing agent include (A) furan-type curing resins that contain active groups that can react with epoxy groups, and (D-2) any curing agent described below. In this way, when the curing agent that can react with the (D-1) epoxy resin is contained in the resin composition layer, it is preferable that the ratio of the number of epoxy groups in the (D-1) epoxy resin to the number of active groups in the curing agent is in a specific range. Specifically, when the number of epoxy groups in the (D-1) epoxy resin is 1, the range of the number of active groups in the curing agent that can react with epoxy groups is preferably 0.1 or more, more preferably 0.2 or more, even more preferably 0.3 or more, and preferably 5.0 or less, more preferably 4.0 or less, even more preferably 3.0 or less. The "number of epoxy groups in the (D-1) epoxy resin" refers to the total sum of all values ​​obtained by dividing the mass of the non-volatile components of the (D-1) epoxy resin present in the resin composition layer by the epoxy equivalent. In addition, the "number of active groups in the active groups of the curing agent capable of reacting with epoxy groups" refers to the total sum of all values ​​obtained by dividing the mass of the non-volatile components of the curing agent present in the resin composition layer by the active group equivalent of the active groups capable of reacting with epoxy groups.

[0178] The optional curable resin (D) may contain an optional curing agent (D-2) capable of reacting with the epoxy resin to cure the resin composition layer. In particular, the optional curable resin (D) preferably contains a combination of the epoxy resin (D-1) and the optional curing agent (D-2). Examples of the optional curing agent (D-2) include phenolic resins, active ester resins, cyanate resins, carbodiimide resins, acid anhydride resins, amine resins, benzoxazine resins, and thiol resins. Among these, phenolic resins and active ester resins are preferred. The optional curing agent (D-2) may be used alone or in combination of two or more.

[0179] As the phenolic resin, a resin having one or more, preferably two or more, hydroxyl groups (phenolic hydroxyl groups) bonded to an aromatic ring such as a benzene ring or a naphthalene ring in one molecule can be used. From the viewpoint of heat resistance and water resistance, a phenolic resin having a novolac structure is preferred. From the viewpoint of adhesion, a nitrogen-containing phenolic resin is preferred, and a triazine skeleton-containing phenolic resin is more preferred. Among them, from the viewpoint of highly satisfying heat resistance, water resistance, and adhesion, a triazine skeleton-containing phenolic novolac resin is preferred. Specific examples of phenolic resins include "MEH-7700", "MEH-7810", and "MEH-7851" manufactured by Meiwa Kasei Co., Ltd.; "NHN", "CBN", and "GPH" manufactured by Nippon Kayaku Co., Ltd.; "SN-170", "SN-180", "SN-190", "SN-475", "SN-485", "SN-495", "SN-375", and "SN-395" manufactured by Nippon Steel Chemical & Material Co., Ltd.; and "LA-7052", "LA-7054", "LA-3018", "LA-3018-50P", "LA-1356", "TD2090", and "TD-2090-60M" manufactured by DIC Corporation.

[0180] The active ester resin may be a resin having one or more, preferably two or more, active ester groups in one molecule. Among them, the active ester resin is preferably a resin having two or more highly reactive ester groups in one molecule, such as phenol esters, thiophenol esters, N-hydroxyamine esters, and esters of heterocyclic hydroxy compounds.

[0181] The active ester resin is preferably one obtained by a condensation reaction between a carboxylic acid compound and / or a thiocarboxylic acid compound and a hydroxy compound and / or a thiol compound. In particular, from the viewpoint of improving heat resistance, an active ester resin obtained from a carboxylic acid compound and a hydroxy compound is preferred, and an active ester resin obtained from a carboxylic acid compound and a phenol compound and / or a naphthol compound is more preferred. Examples of the carboxylic acid compound include benzoic acid, acetic acid, succinic acid, maleic acid, itaconic acid, phthalic acid, isophthalic acid, terephthalic acid, and pyromellitic acid. Examples of phenol compounds or naphthol compounds include hydroquinone, resorcin, bisphenol A, bisphenol F, bisphenol S, phenolphthaline, methylated bisphenol A, methylated bisphenol F, methylated bisphenol S, phenol, o-cresol, m-cresol, p-cresol, catechol, α-naphthol, β-naphthol, 1,5-dihydroxynaphthalene, 1,6-dihydroxynaphthalene, 2,6-dihydroxynaphthalene, dihydroxybenzophenone, trihydroxybenzophenone, tetrahydroxybenzophenone, phloroglucin, benzenetriol, dicyclopentadiene-type diphenol compounds, phenol novolac, etc. Here, the term "dicyclopentadiene-type diphenol compounds" refers to diphenol compounds obtained by condensing one molecule of dicyclopentadiene with two molecules of phenol.

[0182] Specifically, the active ester resin is preferably a dicyclopentadiene type active ester resin, a naphthalene type active ester resin containing a naphthalene structure, an active ester resin containing an acetylated product of phenol novolac, or an active ester resin containing a benzoylated product of phenol novolac, and more preferably at least one selected from a dicyclopentadiene type active ester resin and a naphthalene type active ester resin. As the dicyclopentadiene type active ester resin, an active ester resin containing a dicyclopentadiene type diphenol structure is preferable.

[0183] Commercially available active ester resins include, for example, active ester resins containing a dicyclopentadiene-type diphenol structure such as "EXB9451", "EXB9460", "EXB9460S", "EXB-8000L", "EXB-8000L-65M", "EXB-8000L-65TM", "HPC-8000L-65TM", "HPC-8000", "HPC-8000-65T", "HPC-8000H", and "HPC-8000H-65TM" (manufactured by DIC Corporation); and active ester resins containing a naphthalene structure such as "HP-B-8151-62T", "EXB-8100L-65T", "EXB-8150-60T", and "EXB-815 Examples of such active ester resins include "EXB9401" (manufactured by DIC Corporation), an active ester resin which is an acetylated product of phenol novolac, such as "DC808" (manufactured by Mitsubishi Chemical Corporation), an active ester resin which is a benzoylated product of phenol novolac, such as "YLH1026", "YLH1030", and "YLH1048" (manufactured by Mitsubishi Chemical Corporation), and an active ester resin which contains a styryl group and a naphthalene structure, such as "PC1300-02-65MA" (manufactured by Air Water Corporation).

[0184] As the carbodiimide resin, a resin having one or more, preferably two or more, carbodiimide structures in one molecule can be used. Specific examples of the carbodiimide resin include aliphatic biscarbodiimides such as tetramethylene-bis(t-butylcarbodiimide) and cyclohexane bis(methylene-t-butylcarbodiimide); aromatic biscarbodiimides such as phenylene-bis(xylylcarbodiimide); aliphatic polycarbodiimides such as polyhexamethylenecarbodiimide, polytrimethylhexamethylenecarbodiimide, polycyclohexylenecarbodiimide, poly(methylenebiscyclohexylenecarbodiimide), and poly(isophoronecarbodiimide); poly(phenylenecarbodiimide), poly(naphthalenecarbodiimide), and the like. Examples of polycarbodiimides include aromatic polycarbodiimides such as poly(methylenediphenylenecarbodiimide), poly(tolylenecarbodiimide), poly(methyldiisopropylphenylenecarbodiimide), poly(triethylphenylenecarbodiimide), poly(diethylphenylenecarbodiimide), poly(triisopropylphenylenecarbodiimide), poly(diisopropylphenylenecarbodiimide), poly(xylylenecarbodiimide), poly(tetramethylxylylenecarbodiimide), poly(methylenediphenylenecarbodiimide), and poly[methylenebis(methylphenylene)carbodiimide]. Commercially available carbodiimide resins include, for example, "Carbodilite V-02B", "Carbodilite V-03", "Carbodilite V-04K", "Carbodilite V-07", and "Carbodilite V-09" manufactured by Nisshinbo Chemical Inc.; and "Stavaxol P", "Stavaxol P400", and "Hi-Kasil 510" manufactured by LANXESS AG.

[0185] As the cyanate resin, a resin having one or more, preferably two or more cyanate groups in one molecule can be used. Examples of the cyanate resin include bifunctional cyanate resins such as bisphenol A dicyanate, polyphenol cyanate (oligo(3-methylene-1,5-phenylene cyanate)), 4,4'-methylenebis(2,6-dimethylphenyl cyanate), 4,4'-ethylidene diphenyl dicyanate, hexafluorobisphenol A dicyanate, 2,2-bis(4-cyanate)phenylpropane, 1,1-bis(4-cyanatephenylmethane), bis(4-cyanate-3,5-dimethylphenyl)methane, 1,3-bis(4-cyanatephenyl-1-(methylethylidene))benzene, bis(4-cyanatephenyl)thioether, and bis(4-cyanatephenyl)ether; polyfunctional cyanate resins derived from phenol novolac and cresol novolac; and prepolymers in which these cyanate resins are partially converted to triazine. Specific examples of cyanate resins include Lonza's "PT30" and "PT60" (both of which are phenol novolac type multifunctional cyanate resins), "BA230" and "BA230S75" (prepolymers in which part or all of bisphenol A dicyanate has been converted into triazine to form a trimer).

[0186] As the acid anhydride resin, a resin having one or more, preferably two or more, acid anhydride groups in one molecule can be used. Specific examples of acid anhydride resins include phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, methylnadic anhydride, hydrogenated methylnadic anhydride, trialkyltetrahydrophthalic anhydride, dodecenyl succinic anhydride, 5-(2,5-dioxotetrahydro-3-furanyl)-3-methyl-3-cyclohexene-1,2-dicarboxylic anhydride, trimellitic anhydride, pyromellitic anhydride, benzophenone tetracarboxylic dianhydride, biphenyl tetracarboxylic dianhydride, naphthalene tetracarboxylic dianhydride, oxydiphthalic dianhydride, 3,3'-4,4'-diphenylsulfone tetracarboxylic dianhydride, ethylene glycol bis(anhydrotrimellitate), and polymeric acid anhydrides such as styrene-maleic acid resin, which is a copolymer of styrene and maleic acid. Commercially available acid anhydride resins include, for example, "HNA-100", "MH-700", "MTA-15", "DDSA", and "OSA" manufactured by New Japan Chemical Co., Ltd.; "YH-306" and "YH-307" manufactured by Mitsubishi Chemical Corporation; "HN-2200" manufactured by Resonaq Corporation; and "EF-30", "EF-40", "EF-60", and "EF-80" manufactured by Cray Valley Chemical Industries, Ltd.

[0187] As the amine resin, a resin having one or more, preferably two or more, amino groups in one molecule can be used. Examples of the amine resin include aliphatic amines, polyether amines, alicyclic amines, aromatic amines, etc., among which aromatic amines are preferred. The amine resin is preferably a primary amine or secondary amine, more preferably a primary amine. Specific examples of the amine resin include 4,4'-methylenebis(2,6-dimethylaniline), 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylsulfone, 3,3'-diaminodiphenylsulfone, m-phenylenediamine, m-xylylenediamine, diethyltoluenediamine, 4,4'-diaminodiphenylether, 3,3'-dimethyl-4,4'-diaminobiphenyl, 2,2'-dimethyl-4,4'-diaminobiphenyl, 3,3'-dihydroxybenzidine, 2,2-bis(3-amino-4-hydroxyphenyl)propionate, and the like. Pan, 3,3-dimethyl-5,5-diethyl-4,4-diphenylmethanediamine, 2,2-bis(4-aminophenyl)propane, 2,2-bis(4-(4-aminophenoxy)phenyl)propane, 1,3-bis(3-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, 1,4-bis(4-aminophenoxy)benzene, 4,4'-bis(4-aminophenoxy)biphenyl, bis(4-(4-aminophenoxy)phenyl)sulfone, bis(4-(3-aminophenoxy)phenyl)sulfone, and the like. Commercially available amine resins include, for example, "SEIKACURE-S" manufactured by Seika Corporation; "KAYABOND C-200S", "KAYABOND C-100", "KAYAHARD AA", "KAYAHARD AB", and "KAYAHARD AS" manufactured by Nippon Kayaku Co., Ltd.; "Epicure W" manufactured by Mitsubishi Chemical Corporation; and "DTDA" manufactured by Sumitomo Seika Chemicals Co., Ltd.

[0188] Specific examples of benzoxazine resins include "JBZ-OP100D" and "ODA-BOZ" manufactured by JFE Chemical Corporation; "HFB2006M" manufactured by Showa Polymer Co., Ltd.; and "Pd" and "Fa" manufactured by Shikoku Chemical Industry Co., Ltd.

[0189] Examples of the thiol resin include trimethylolpropane tris(3-mercaptopropionate), pentaerythritol tetrakis(3-mercaptobutyrate), tris(3-mercaptopropyl)isocyanurate, and the like.

[0190] (D-2) The range of the active group equivalent of any curing agent is preferably 50 g / eq. to 3000 g / eq., more preferably 100 g / eq. to 1000 g / eq., still more preferably 100 g / eq. to 500 g / eq., and particularly preferably 100 g / eq. to 300 g / eq.

[0191] (D-2) The range of the weight average molecular weight of any curing agent may be the same as the range of the weight average molecular weight (Mw) of the epoxy resin in (D-1).

[0192] The range of the amount of any curing agent (D-2) in the resin composition layer is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, still more preferably 0.5% by mass or more, and preferably 20% by mass or less, more preferably 15% by mass or less, and particularly preferably 10% by mass or less with respect to 100% by mass of the non-volatile components in the resin composition layer.

[0193] The range of the amount of any curing agent (D-2) in the resin composition layer is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, still more preferably 1% by mass or more, and preferably 50% by mass or less, more preferably 40% by mass or less, and still more preferably 30% by mass or less with respect to 100% by mass of the resin components in the resin composition layer.

[0194] The optional curable resin (D) may contain a radically polymerizable resin (D-3). The radically polymerizable resin (D-3) usually contains a non-aromatic carbon-carbon unsaturated bond. Therefore, a resin containing a radically reactive unsaturated group may be used as the radically polymerizable resin (D-3). The radically polymerizable resin (D-3) may be one in which the radically polymerizable resin (D-3) reacts with itself, or one in which the radically polymerizable resin (D-3) and the furan-type curable resin (A) undergo a reaction such as a Diels-Alder reaction. Such a radically polymerizable resin (D-3) preferably has two or more radically reactive unsaturated groups.

[0195] Examples of the (D-3) radical polymerizable resin include (meth)acrylic radical polymerizable resins, styrene radical polymerizable resins, allyl radical polymerizable resins, maleimide radical polymerizable resins, etc. The (D-3) radical polymerizable resins may be used alone or in combination of two or more.

[0196] As the (meth)acrylic radical polymerizable resin, a resin having one or more, preferably two or more, acryloyl groups and / or methacryloyl groups in one molecule can be used. As the (meth)acrylic radical polymerizable resin, for example, cyclohexane-1,4-dimethanol di(meth)acrylate, cyclohexane-1,3-dimethanol di(meth)acrylate, tricyclodecane dimethanol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,8-octanediol di(meth)acrylate, 1,9-nonane dimethanol ... Low molecular weight (molecular weight less than 1000) aliphatic (meth)acrylic acid ester compounds such as diol di(meth)acrylate, 1,10-decanediol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, trimethylolethane tri(meth)acrylate, glycerin tri(meth)acrylate, and pentaerythritol tetra(meth)acrylate; dioxane glycol di(meth)acrylate, 3,6-dioxa-1,8-octanediol di(meth)acrylate, ) acrylate, 3,6,9-trioxaundecane-1,11-diol di(meth)acrylate, polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, 9,9-bis[4-(2-acryloyloxyethoxy)phenyl]fluorene, ethoxylated bisphenol A di(meth)acrylate, propoxylated bisphenol A di(meth)acrylate, and other low molecular weight (molecular weight less than 1000) ether-containing (meth)acrylic acid ester compounds; tris(3-hydroxypropyl)isocyanurate tri(meth)acrylate, tris(2-hydroxyethyl)isocyanurate tri(meth)acrylate, and other low molecular weight (molecular weight less than 1000) isocyanurate-containing (meth)acrylic acid ester compounds; and high molecular weight (molecular weight 1000 or more) acrylic acid ester compounds such as (meth)acrylic modified polyphenylene ether resins. As used herein, the term "(meth)acrylic acid" includes acrylic acid, methacrylic acid, and combinations thereof.The term "(meth)acrylate" includes acrylate, methacrylate, and combinations thereof. Commercially available (meth)acrylic radical polymerizable resins include, for example, "A-DOG" (dioxane glycol diacrylate) manufactured by Shin-Nakamura Chemical Co., Ltd., "DCP-A" (tricyclodecane dimethanol diacrylate), "DCP" (tricyclodecane dimethanol dimethacrylate), and "BPE-1300N" (ethoxylated bisphenol A dimethacrylate) manufactured by Kyoeisha Chemical Co., Ltd., "KAYARAD R-684" (tricyclodecane dimethanol diacrylate) and "KAYARAD R-604" (dioxane glycol diacrylate) manufactured by Nippon Kayaku Co., Ltd., and "SA9000" and "SA9000-111" (methacrylic modified polyphenylene ether) manufactured by SABIC.

[0197] As the styrene radical polymerizable resin, a resin having one or more, preferably two or more, vinyl groups directly bonded to an aromatic carbon atom in one molecule can be used. As the styrene radical polymerizable resin, for example, low molecular weight (molecular weight less than 1000) styrene 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; high molecular weight (molecular weight 1000 or more) styrene compounds such as vinylbenzyl-modified polyphenylene ether resin and styrene-divinylbenzene copolymer can be mentioned. Commercially available styrene-based radical polymerizable resins include, for example, "ODV-XET(X03)", "ODV-XET(X04)", and "ODV-XET(X05)" (styrene-divinylbenzene copolymers) manufactured by Nippon Steel Chemical & Material Co., Ltd., and "OPE-2St 1200" and "OPE-2St 2200" (vinylbenzyl-modified polyphenylene ether resins) manufactured by Mitsubishi Gas Chemical Co., Inc.

[0198] As the allyl radical polymerizable resin, a resin having one or more, preferably two or more allyl groups in one molecule can be used. Examples of the allyl radical polymerizable resin 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-naphthalenecarboxylate; allyl isocyanurate ester compounds such as 1,3,5-triallyl isocyanurate and 1,3-diallyl-5-glycidyl isocyanurate; epoxy-containing aromatic allyl compounds such as 2,2-bis[3-allyl-4-(glycidyloxy)phenyl]propane; benzoxazine-containing aromatic allyl compounds such as bis[3-allyl-4-(3,4-dihydro-2H-1,3-benzoxazin-3-yl)phenyl]methane; ether-containing aromatic allyl compounds such as 1,3,5-triallyl ether benzene; and allyl silane compounds such as diallyl diphenylsilane. Commercially available products of the allyl radical polymerizable resin include, for example, "TAIC" (1,3,5-triallyl isocyanurate) manufactured by Nippon Kasei Co., Ltd., "DAD" (diallyl diphenate) manufactured by Nisshoku Techno Fine Chemical Co., Ltd., "TRIAM-705" (triallyl trimellitate) manufactured by Fujifilm Wako Pure Chemical Corporation, the product name "DAND" (diallyl 2,3-naphthalenecarboxylate) manufactured by Nisshoku Techno Fine Chemical Co., Ltd., "ALP-d" (bis[3-allyl-4-(3,4-dihydro-2H-1,3-benzoxazin-3-yl)phenyl]methane) manufactured by Shikoku Kasei Kogyo Co., Ltd., "RE-810NM" (2,2-bis[3-allyl-4-(glycidyloxy)phenyl]propane) manufactured by Nippon Kayaku Co., Ltd., "DA-MGIC" (1,3-diallyl-5-glycidyl isocyanurate) manufactured by Shikoku Kasei Kogyo Co., Ltd., and the like.

[0199] The maleimide radical polymerizable resin may be a resin having one or more, preferably two or more, maleimide groups in one molecule. The maleimide radical polymerizable resin may be an aromatic maleimide resin having a maleimide group directly bonded to an aromatic ring, or an aliphatic maleimide resin having no maleimide group directly bonded to an aromatic ring. Commercially available maleimide radical polymerizable resins include, for example, "SLK-2600" manufactured by Shin-Etsu Chemical Co., Ltd., "BMI-1500", "BMI-1700", "BMI-3000J", "BMI-689", and "BMI-2500" (dimer diamine structure-containing maleimide compounds) manufactured by Designer Molecules Inc., "BMI-6100" (aromatic maleimide compound) manufactured by Designer Molecules Inc., "MIR-5000-60T" and "MIR-3000-70MT" (biphenylaralkyl-type maleimide compounds) manufactured by Nippon Kayaku Co., Ltd., "BMI-70" and "BMI-80" manufactured by K.I. Chemical Industry Co., Ltd., and "BMI-2300" and "BMI-TMH" manufactured by Daiwa Kasei Kogyo Co., Ltd. In addition, as the maleimide-based radically polymerizable resin, a maleimide resin (an indane ring skeleton-containing maleimide compound) disclosed in the Japan Institute of Invention and Innovation's Technical Journal Publication No. 2020-500211 may be used.

[0200] The radical polymerizable group equivalent of the (D-3) radical polymerizable resin is preferably 20 g / eq. to 3,000 g / eq., more preferably 50 g / eq. to 2,500 g / eq., further preferably 70 g / eq. to 2,000 g / eq., and particularly preferably 90 g / eq. to 1,500 g / eq. The radical polymerizable group equivalent represents the mass of the resin per equivalent of the radical polymerizable group.

[0201] The weight average molecular weight (Mw) of the radical polymerizable resin (D-3) is preferably 40,000 or less, more preferably 10,000 or less, further preferably 5,000 or less, and particularly preferably 3,000 or less. The lower limit is not particularly limited, but may be, for example, 150 or more.

[0202] The amount of the radically polymerizable resin (D-3) in the resin composition layer is preferably 0.1% by mass or more, more preferably 0.3% by mass or more, and even more preferably 0.5% by mass or more, relative to 100% by mass of the non-volatile components in the resin composition layer, and is preferably 10% by mass or less, more preferably 5% by mass or less, and even more preferably 3% by mass or less.

[0203] The range of the amount of the radically polymerizable resin (D-3) in the resin composition layer is, relative to 100% by mass of the resin components in the resin composition layer, preferably 0.1% by mass or more, more preferably 1% by mass or more, even more preferably 2% by mass or more, and is preferably 30% by mass or less, more preferably 20% by mass or less, even more preferably 10% by mass or less.

[0204] The range of the amount of (D) optional curable resin in the resin composition layer is preferably 1 mass% or more, more preferably 5 mass% or more, even more preferably 10 mass% or more, relative to 100 mass% of the non-volatile components in the resin composition layer, and is preferably 45 mass% or less, more preferably 40 mass% or less, and particularly preferably 30 mass% or less.

[0205] The range of the amount of the optional curable resin (D) in the resin composition layer is, relative to 100 mass% of the resin components in the resin composition layer, preferably 10 mass% or more, more preferably 20 mass% or more, even more preferably 30 mass% or more, and is preferably 95 mass% or less, more preferably 90 mass% or less, and particularly preferably 80 mass% or less.

[0206] <(E) Curing catalyst> The resin composition layer of the resin sheet may contain, as an optional component, a curing catalyst (E) that promotes the reaction of a curing resin such as a furan-type curing resin (A) and an optional curing resin (D). The curing catalyst (E) as the component (E) does not include those corresponding to the above-mentioned components (A) to (D). The curing catalyst (E) as the component (E) may be used alone or in combination of two or more kinds.

[0207] (E) The curing catalyst may be, for example, a curing accelerator as a catalyst for accelerating the reaction of an epoxy resin. Examples of the curing accelerator include phosphorus-based curing accelerators, urea-based curing accelerators, guanidine-based curing accelerators, imidazole-based curing accelerators, metal-based curing accelerators, and amine-based curing accelerators. The curing accelerator may be used alone or in combination of two or more.

[0208] Examples of the phosphorus-based curing accelerator include aliphatic phosphonium salts such as tetrabutyl phosphonium bromide, tetrabutyl phosphonium chloride, tetrabutyl phosphonium acetate, tetrabutyl phosphonium decanoate, tetrabutyl phosphonium laurate, bis(tetrabutyl phosphonium)pyromellitate, tetrabutyl phosphonium hydrogenhexahydrophthalate, tetrabutyl phosphonium 2,6-bis[(2-hydroxy-5-methylphenyl)methyl]-4-methylphenolate, and di-tert-butyldimethylphosphonium tetraphenylborate; methyl triphenyl phosphonium bromide, ethyl triphenyl phosphonium bromide, propyl triphenyl phosphonium bromide, butyl triphenyl phosphonium bromide, benzyl triphenyl phosphonium chloride, tetraphenyl phosphonium bromide, p-tolyl triphenyl phosphonium tetra-p-tolylborate, tetraphenyl phosphonium bromide, and the like. aromatic phosphonium salts such as tetraphenylborate, tetraphenylphosphonium tetra-p-tolylborate, triphenylethylphosphonium tetraphenylborate, tris(3-methylphenyl)ethylphosphonium tetraphenylborate, tris(2-methoxyphenyl)ethylphosphonium tetraphenylborate, (4-methylphenyl)triphenylphosphonium thiocyanate, tetraphenylphosphonium thiocyanate, and butyltriphenylphosphonium thiocyanate; aromatic phosphine-borane complexes such as triphenylphosphine-triphenylborane; aromatic phosphine-quinone adducts such as triphenylphosphine-p-benzoquinone adduct; aliphatic phosphines such as tributylphosphine, tri-tert-butylphosphine, trioctylphosphine, di-tert-butyl(2-butenyl)phosphine, di-tert-butyl(3-methyl-2-butenyl)phosphine, and tricyclohexylphosphine;Dibutylphenylphosphine, di-tert-butylphenylphosphine, methyldiphenylphosphine, ethyldiphenylphosphine, butyldiphenylphosphine, diphenylcyclohexylphosphine, triphenylphosphine, tri-o-tolylphosphine, tri-m-tolylphosphine, tri-p-tolylphosphine, tris(4-ethylphenyl)phosphine, tris(4-propylphenyl)phosphine, tris(4-isopropylphenyl)phosphine, tris(4-butylphenyl)phosphine, tris(4-tert-butylphenyl)phosphine, tris(2,4-dimethylphenyl)phosphine, tris(2,5-dimethylphenyl)phosphine, tris(2,6-dimethylphenyl)phosphine Examples of the aromatic phosphines include 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. Examples of commercially available phosphorus-based curing accelerators include "TBP-DA" manufactured by Hokko Chemical Industry Co., Ltd.;

[0209] Examples of the urea-based curing accelerator include 1,1-dimethylurea; aliphatic dimethylureas such as 1,1,3-trimethylurea, 3-ethyl-1,1-dimethylurea, 3-cyclohexyl-1,1-dimethylurea, and 3-cyclooctyl-1,1-dimethylurea; 3-phenyl-1,1-dimethylurea, 3-(4-chlorophenyl)-1,1-dimethylurea, 3-(3,4-dichlorophenyl)-1,1-dimethylurea, 3-(3-chloro-4-methylphenyl)-1,1-dimethylurea, 3-(2-methylphenyl)-1,1-dimethylurea, 3-(4-methylphenyl)-1,1-dimethylurea, and 3-(3,4-dimethylphenyl)-1,1-dimethylurea. aromatic dimethylureas such as butylurea, 3-(4-isopropylphenyl)-1,1-dimethylurea, 3-(4-methoxyphenyl)-1,1-dimethylurea, 3-(4-nitrophenyl)-1,1-dimethylurea, 3-[4-(4-methoxyphenoxy)phenyl]-1,1-dimethylurea, 3-[4-(4-chlorophenoxy)phenyl]-1,1-dimethylurea, 3-[3-(trifluoromethyl)phenyl]-1,1-dimethylurea, N,N-(1,4-phenylene)bis(N',N'-dimethylurea), and N,N-(4-methyl-1,3-phenylene)bis(N',N'-dimethylurea) [toluene bisdimethylurea].

[0210] Examples of the guanidine curing accelerator include dicyandiamide, 1-methylguanidine, 1-ethylguanidine, 1-cyclohexylguanidine, 1-phenylguanidine, 1-(o-tolyl)guanidine, dimethylguanidine, diphenylguanidine, trimethylguanidine, tetramethylguanidine, pentamethylguanidine, 1,5,7-triazabicyclo[4.4.0]dec-5-ene, 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene, 1-methylbiguanide, 1-ethylbiguanide, 1-n-butylbiguanide, 1-n-octadecylbiguanide, 1,1-dimethylbiguanide, 1,1-diethylbiguanide, 1-cyclohexylbiguanide, 1-allylbiguanide, 1-phenylbiguanide, and 1-(o-tolyl)biguanide.

[0211] Examples of the imidazole-based curing accelerator include 2-methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 1,2-dimethylimidazole, 2-ethyl-4-methylimidazole, 1,2-dimethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 1-benzyl-2-methylimidazole, and 1-benzyl-2-methylimidazole. Phenylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-undecylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 1-cyanoethyl-2-phenylimidazole, 1-cyanoethyl-2-undecylimidazolium trimellitate, 1-cyanoethyl-2-phenylimidazolium trimellitate, 2,4-diamino-6-[2'-methylimidazolyl -(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-undecylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-ethyl-4'-methylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine isocyanuric acid adduct, 2-phenylimidazole isocyanuric acid adduct , 2-phenyl-4,5-dihydroxymethylimidazole, 2-phenyl-4-methyl-5-hydroxymethylimidazole, 2,3-dihydro-1H-pyrrolo[1,2-a]benzimidazole, 1-dodecyl-2-methyl-3-benzylimidazolium chloride, 2-methylimidazoline, 2-phenylimidazoline, and other imidazole compounds and adducts of imidazole compounds and epoxy resins. Commercially available imidazole curing accelerators include, for example, "1B2PZ", "2E4MZ", "2MZA-PW", "2MZ-OK", "2MA-OK", "2MA-OK-PW", "2PHZ", "2PHZ-PW", "Cl1Z", "Cl1Z-CN", "Cl1Z-CNS", and "C11Z-A" manufactured by Shikoku Chemical Industry Co., Ltd.; and "P200-H50" manufactured by Mitsubishi Chemical Corporation.

[0212] Examples of the metal-based hardening accelerator include organometallic complexes or organometallic salts of metals such as cobalt, copper, zinc, iron, nickel, manganese, and tin. Specific examples of the organometallic complexes include organocobalt complexes such as cobalt(II) acetylacetonate and cobalt(III) acetylacetonate, organocopper complexes such as copper(II) acetylacetonate, organozinc complexes such as zinc(II) acetylacetonate, organoiron complexes such as iron(III) acetylacetonate, organonickel complexes such as nickel(II) acetylacetonate, and organomanganese complexes such as manganese(II) acetylacetonate. Examples of the organometallic salts include zinc octylate, tin octylate, zinc naphthenate, cobalt naphthenate, tin stearate, and zinc stearate.

[0213] Examples of the amine-based hardening accelerator include trialkylamines such as triethylamine and tributylamine, 4-dimethylaminopyridine, benzyldimethylamine, 2,4,6-tris(dimethylaminomethyl)phenol, 1,8-diazabicyclo(5,4,0)undecene, and the like. Examples of commercially available amine-based hardening accelerators include "MY-25" manufactured by Ajinomoto Fine-Techno Co., Inc.

[0214] The range of the amount of the hardening accelerator in the resin composition layer is preferably 0.01% by mass or more, more preferably 0.02% by mass or more, still more preferably 0.05% by mass or more, and preferably 2% by mass or less, more preferably 1% by mass or less, still more preferably 0.5% by mass or less with respect to 100% by mass of the nonvolatile components in the resin composition layer.

[0215] The range of the amount of the hardening accelerator in the resin composition layer is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, still more preferably 0.2% by mass or more, and preferably 5% by mass or less, more preferably 2% by mass or less, still more preferably 1% by mass or less with respect to 100% by mass of the resin components in the resin composition layer.

[0216] (E) The curing catalyst may be, for example, a radical polymerization initiator as a catalyst for radical reaction. The radical polymerization initiator may be used alone or in any combination of two or more. Examples of the radical polymerization initiator include a peroxide radical polymerization initiator and an azo radical polymerization initiator.

[0217] Examples of the peroxide radical polymerization initiator include hydroperoxide compounds such as 1,1,3,3-tetramethylbutyl hydroperoxide; dialkyl peroxide compounds such as tert-butylcumyl peroxide, di-tert-butyl peroxide, di-tert-hexyl peroxide, dicumyl peroxide, 1,4-bis(1-tert-butylperoxy-1-methylethyl)benzene, and 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane; and diacyl peroxide compounds such as dilauroyl peroxide, didecanoyl peroxide, dicyclohexyl peroxydicarbonate, and bis(4-tert-butylcyclohexyl)peroxydicarbonate. peroxyester compounds such as tert-butyl peroxyacetate, tert-butyl peroxybenzoate, tert-butyl peroxyisopropyl monocarbonate, tert-butyl peroxy-2-ethylhexanoate, tert-butyl peroxyneodecanoate, tert-hexylperoxyisopropyl monocarbonate, tert-butyl peroxylaurate, (1,1-dimethylpropyl)2-ethylperhexanoate, tert-butyl 2-ethylperhexanoate, tert-butyl 3,5,5-trimethylperhexanoate, tert-butylperoxy-2-ethylhexyl monocarbonate, and tert-butylperoxymaleic acid.

[0218] Examples of the azo radical polymerization initiator include azonitrile compounds such as 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobisisobutyronitrile, 2,2'-azobis(2-methylbutyronitrile), 1,1'-azobis(cyclohexane-1-carbonitrile), 1-[(1-cyano-1-methylethyl)azo]formamide, and 2-phenylazo-4-methoxy-2,4-dimethyl-valeronitrile; 2,2'-azobis[2-methyl-N-[1,1-bis(hydroxymethyl)-2-hydroxyethyl]propionamide], 2,2'-azobis[2-methyl-N-[1,1-bis(hydroxymethyl)-2-hydroxyethyl]propionamide], and the like. azo amide compounds such as 2,2'-azobis[2-methyl-N-[2-(1-hydroxybutyl)]-propionamide], 2,2'-azobis[2-methyl-N-(2-hydroxyethyl)-propionamide], 2,2'-azobis(2-methylpropionamide) dihydrate, 2,2'-azobis[N-(2-propenyl)-2-methylpropionamide], 2,2'-azobis(N-butyl-2-methylpropionamide), and 2,2'-azobis(N-cyclohexyl-2-methylpropionamide); alkyl azo compounds such as 2,2'-azobis(2,4,4-trimethylpentane) and 2,2'-azobis(2-methylpropane); and the like.

[0219] Commercially available radical polymerization initiators include, for example, “Perbutyl C”, “Perbutyl A”, “Perbutyl P”, “Perbutyl L”, “Perbutyl O”, “Perbutyl ND”, “Perbutyl Z”, “Perbutyl I”, “Percumyl P”, “Percumyl D”, “Perhexyl D”, “Perhexyl A”, “Perhexyl I”, “Perhexyl Z”, “Perhexyl ND”, “Perhexyl O”, and “Perhexyl PV”, all manufactured by NOF Corporation.

[0220] The range of the amount of the radical polymerization initiator in the resin composition layer is preferably 0.01 mass% or more, more preferably 0.02 mass% or more, even more preferably 0.05 mass% or more, and is preferably 2 mass% or less, more preferably 1 mass% or less, even more preferably 0.5 mass% or less, relative to 100 mass% of the non-volatile components in the resin composition layer.

[0221] The range of the amount of the radical polymerization initiator in the resin composition layer is, relative to 100 mass% of the resin component in the resin composition layer, preferably 0.01 mass% or more, more preferably 0.1 mass% or more, even more preferably 0.2 mass% or more, and is preferably 5 mass% or less, more preferably 2 mass% or less, even more preferably 1 mass% or less.

[0222] The amount of the (E) curing catalyst in the resin composition layer is preferably 0.01 mass% or more, more preferably 0.02 mass% or more, and even more preferably 0.05 mass% or more, relative to 100 mass% of the non-volatile components in the resin composition layer, and is preferably 2 mass% or less, more preferably 1 mass% or less, and even more preferably 0.5 mass% or less.

[0223] The amount of the (E) curing catalyst in the resin composition layer is preferably 0.01 mass% or more, more preferably 0.1 mass% or more, and even more preferably 0.2 mass% or more, relative to 100 mass% of the resin component in the resin composition layer, and is preferably 5 mass% or less, more preferably 2 mass% or less, and even more preferably 1 mass% or less.

[0224] <(F) Polymer resin> The resin composition layer of the resin sheet may contain a polymer resin (F) as an optional component. The polymer resin (F) as the component (F) does not include those corresponding to the above-mentioned components (A) to (E). The polymer resin (F) usually has thermoplasticity and is contained in the resin composition layer in a state of being compatible with resin components other than the polymer resin (F). The polymer resin (F) may be used alone or in combination of two or more kinds.

[0225] Examples of the (F) polymer resin include phenoxy resin, acrylic resin, polyimide resin, polyvinyl acetal resin, polyolefin resin, polybutadiene resin, polyamideimide resin, polyetherimide resin, polysulfone resin, polyethersulfone resin, polyphenylene ether resin, polycarbonate resin, polyetheretherketone resin, and polyester resin.

[0226] Examples of the phenoxy resin include phenoxy resins having one or more skeletons selected from the group consisting of bisphenol A skeleton, bisphenol F skeleton, bisphenol S skeleton, bisphenolacetophenone skeleton, novolac skeleton, biphenyl skeleton, fluorene skeleton, dicyclopentadiene skeleton, norbornene skeleton, naphthalene skeleton, anthracene skeleton, adamantane skeleton, terpene skeleton, and trimethylcyclohexane skeleton. The terminal of the phenoxy resin may be any functional group such as a phenolic hydroxyl group or an epoxy group. Specific examples of phenoxy resins include "1256" and "4250" manufactured by Mitsubishi Chemical Corporation (both of which are phenoxy resins containing a bisphenol A skeleton); "YX8100" manufactured by Mitsubishi Chemical Corporation (phenoxy resin containing a bisphenol S skeleton); "YX6954" manufactured by Mitsubishi Chemical Corporation (phenoxy resin containing a bisphenol acetophenone skeleton); "FX280" and "FX293" manufactured by Nippon Steel Chemical & Material Co., Ltd.; "YL7500BH30", "YX6954BH30", "YX7553", "YX7553BH30", "YL7769BH30", "YL6794", "YL7213", "YL7290", "YL7482", and "YL7891BH30" manufactured by Mitsubishi Chemical Corporation.

[0227] Examples of acrylic resins include resins containing a (meth)acrylate structure. The acrylic resin may contain a (meth)acrylate structure in the main chain or in the side chain. Here, the term "(meth)acrylate structure" includes both acrylate and methacrylate structures. Specific examples of acrylic resins include Teisan Resin "SG-70L", "SG-708-6", "WS-023", "SG-700AS", "SG-280TEA", "SG-80H", "SG-80H-3", "SG-P3", "SG-600TEA", and "SG-790" manufactured by Nagase ChemteX Corporation; "ME-2000", "W-116.3", "W-197C", "KG-25", and "KG-3000" manufactured by Negami Chemical Industries Co., Ltd.; and "ARUFON UH-2000" manufactured by Toagosei Co., Ltd.

[0228] Specific examples of polyimide resins include "SLK-6100" manufactured by Shin-Etsu Chemical Co., Ltd., and "Rikacoat SN20" and "Rikacoat PN20" manufactured by New Japan Chemical Co., Ltd. Specific examples of polyimide resins also include modified polyimides such as linear polyimides obtained by reacting bifunctional hydroxyl-terminated polybutadiene, a diisocyanate compound, and a tetrabasic acid anhydride (polyimides described in JP-A-2006-37083), and polysiloxane skeleton-containing polyimides (polyimides described in JP-A-2002-12667 and JP-A-2000-319386, etc.).

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

[0230] Examples of the polyolefin resin include ethylene-based copolymer resins such as low density polyethylene, ultra-low density polyethylene, high density polyethylene, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, and ethylene-methyl acrylate copolymer; polyolefin polymers such as polypropylene and ethylene-propylene block copolymer, etc.

[0231] Examples of polybutadiene resins include hydrogenated polybutadiene skeleton-containing resins, hydroxyl group-containing polybutadiene resins, phenolic hydroxyl group-containing polybutadiene resins, carboxyl group-containing polybutadiene resins, acid anhydride group-containing polybutadiene resins, epoxy group-containing polybutadiene resins, isocyanate group-containing polybutadiene resins, urethane group-containing polybutadiene resins, polyphenylene ether-polybutadiene resins, etc. A part or all of the polybutadiene structure of the polybutadiene resin may be hydrogenated. Specific examples of polybutadiene resins include "Ricon 130MA8", "Ricon 130MA13", "Ricon 130MA20", "Ricon 131MA5", "Ricon 131MA10", "Ricon 131MA17", "Ricon 131MA20", and "Ricon 184MA6" (polybutadiene containing an acid anhydride group) manufactured by Cray Valley Corporation; "GQ-1000" (polybutadiene having hydroxyl groups and carboxyl groups introduced therein), "G-1000", "G-2000", and "G-3000" (polybutadiene having hydroxyl groups at both ends), "GI-1000", "GI-2000", and "GI-3000" (polybutadiene having hydrogenated hydroxyl groups at both ends) manufactured by Nippon Soda Co., Ltd.; and "FCA-061L" (hydrogenated polybutadiene skeleton epoxy resin) manufactured by Nagase ChemteX Corporation. Specific examples of polybutadiene resins include polyimide resins having a polybutadiene structure, a urethane structure, and an imide structure in the molecule. The polyimide resin can be produced as a linear polyimide resin (polyimide described in JP 2006-37083 A and WO 2008 / 153208 A) using hydroxyl-terminated polybutadiene, a diisocyanate compound, and a tetrabasic acid anhydride as raw materials. The content of the butadiene structure in the polyimide resin is preferably 60% by mass to 95% by mass, more preferably 75% by mass to 85% by mass. Details of the polyimide resin can be found in JP 2006-37083 A and WO 2008 / 153208 A, the contents of which are incorporated herein by reference.

[0232] Specific examples of polyamide-imide resins include "Viromax HR11NN" and "Viromax HR16NN" manufactured by Toyobo Co., Ltd. Specific examples of polyamide-imide resins also include modified polyamide-imides such as "KS9100" and "KS9300" (polysiloxane skeleton-containing polyamide-imide) manufactured by Hitachi Chemical Co., Ltd.

[0233] A specific example of the polyetherimide resin is "Ultem" manufactured by GE.

[0234] Specific examples of polysulfone resins include polysulfones "P1700" and "P3500" manufactured by Solvay Advanced Polymers.

[0235] A specific example of the polyethersulfone resin is "PES5003P" manufactured by Sumitomo Chemical Co., Ltd.

[0236] A specific example of the polyphenylene ether resin is "NORYL SA90" manufactured by SABIC.

[0237] Examples of polycarbonate resins include hydroxyl group-containing carbonate resins, phenolic hydroxyl group-containing carbonate resins, carboxyl group-containing carbonate resins, acid anhydride group-containing carbonate resins, isocyanate group-containing carbonate resins, and urethane group-containing carbonate resins. Specific examples of polycarbonate resins include Mitsubishi Gas Chemical's "FPC0220," Asahi Kasei's "T6002" and "T6001" (polycarbonate diols), and Kuraray's "C-1090," "C-2090," and "C-3090" (polycarbonate diols). Specific examples of polycarbonate resins include polyimide resins having an imide structure, a urethane structure, and a polycarbonate structure in the molecule. The polyimide resin can be produced as a linear polyimide resin using hydroxyl group-terminated polycarbonate, a diisocyanate compound, and a tetrabasic acid anhydride as raw materials. The content of the carbonate structure in the polyimide resin is preferably 60% by mass to 95% by mass, more preferably 75% by mass to 85% by mass. For details of the polyimide resin, refer to the description in International Publication No. 2016 / 129541, the contents of which are incorporated herein by reference.

[0238] A specific example of the polyether ether ketone resin is "Sumiploy K" manufactured by Sumitomo Chemical Co., Ltd.

[0239] Examples of polyester resins include polyethylene terephthalate resins, polyethylene naphthalate resins, polybutylene terephthalate resins, polybutylene naphthalate resins, polytrimethylene terephthalate resins, polytrimethylene naphthalate resins, and polycyclohexane dimethyl terephthalate resins.

[0240] The (F) polymer resin usually has a large molecular weight. Specifically, the range of 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, and preferably 100,000 or less, more preferably 70,000 or less, even more preferably 60,000 or less, even more preferably 50,000 or less. The weight average molecular weight Mw can be measured in terms of polystyrene by gel permeation chromatography (GPC).

[0241] The range of the amount of the (F) polymer resin in the resin composition layer is, relative to 100 mass% of the non-volatile components in the resin composition layer, preferably 0.1 mass% or more, more preferably 0.2 mass% or more, even more preferably 0.5 mass% or more, and is preferably 10 mass% or less, more preferably 8 mass% or less, even more preferably 5 mass% or less.

[0242] The range of the amount of the (F) polymer resin in the resin composition layer is, relative to 100 mass% of the resin components in the resin composition layer, preferably 0.1 mass% or more, more preferably 0.5 mass% or more, even more preferably 1 mass% or more, and is preferably 20 mass% or less, more preferably 10 mass% or less, even more preferably 5 mass% or less.

[0243] <(G)Organic filler> The resin composition layer of the resin sheet may contain an organic filler (G) as an optional component. The organic filler (G) as the component (G) does not include those corresponding to the above-mentioned components (A) to (F). The organic filler (G) is usually not compatible with resin components other than the organic filler (G) and is contained in the resin composition layer in the form of particles, and is contained in the insulating layer while maintaining the particle state. In addition, the organic filler (G) as the component (G) may be used alone or in combination of two or more types.

[0244] As the (G) organic filler, particles of an organic material may be used. As the organic material contained in the (G) organic filler, a rubber component is preferable. Examples of the rubber component include silicone-based elastomers such as polydimethylsiloxane; olefin-based thermoplastic elastomers such as polybutadiene, polyisoprene, polychlorobutadiene, ethylene-vinyl acetate copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-isobutylene copolymer, acrylonitrile-butadiene copolymer, isoprene-isobutylene copolymer, isobutylene-butadiene copolymer, ethylene-propylene-diene terpolymer, and ethylene-propylene-butene terpolymer; and thermoplastic elastomers such as acrylic thermoplastic elastomers such as polypropyl(meth)acrylate, polybutyl(meth)acrylate, polycyclohexyl(meth)acrylate, and polyoctyl(meth)acrylate. Furthermore, silicone-based rubbers such as polyorganosiloxane rubber may be mixed into the rubber component. The rubber component contained in the rubber particles has a glass transition temperature of, for example, 0° C. or lower, preferably −10° C. or lower, more preferably −20° C. or lower, and even more preferably −30° C. or lower.

[0245] The (G) organic filler may be a core-shell type rubber particle consisting of a core particle containing the above-mentioned rubber component and a shell portion obtained by graft copolymerization of a monomer component copolymerizable with the rubber component contained in the core particle. Here, the term "core-shell type" does not necessarily refer only to those in which the core particle and the shell portion are clearly distinguishable, but also includes those in which the boundary between the core particle and the shell portion is unclear, and the core particle does not necessarily have to be completely covered with the shell portion.

[0246] Specific examples of the (G) organic filler include, for example, "CHT" manufactured by Samsung SDI; "B602" manufactured by Techno UMG; "Paraloid EXL-2602", "Paraloid EXL-2603", "Paraloid EXL-2655", "Paraloid EXL-2311", "Paraloid-EXL2313", "Paraloid EXL-2315", "Paraloid KM-330", "Paraloid KM-336P", and "Paraloid KCZ-201" manufactured by Dow; and "Metabrene C-223A" and "Metabrene E- 901", "Metabrene S-2001", "Metabrene W-450A", "Metabrene SRK-200", Kaneka Corporation's "Kane Ace M-511", "Kane Ace M-600", "Kane Ace M-400", "Kane Ace M-580", and "Kane Ace MR-01", Aica Kogyo Co., Ltd.'s "Staphyloid AC3355", "Staphyloid AC3816", "Staphyloid AC3816N", "Staphyloid AC3832", "Staphyloid AC4030", and "Staphyloid AC3364".

[0247] The amount of the (G) organic filler in the resin composition layer is preferably 0.1% by mass or more, more preferably 0.2% by mass or more, and even more preferably 0.5% by mass or more, relative to 100% by mass of the non-volatile components in the resin composition layer, and is preferably 5% by mass or less, more preferably 2% by mass or less, and even more preferably 1% by mass or less.

[0248] The amount of the (G) organic filler in the resin composition layer is preferably 0.1 mass% or more, more preferably 0.5 mass% or more, and even more preferably 1 mass% or more, relative to 100 mass% of the resin component in the resin composition layer, and is preferably 10 mass% or less, more preferably 5 mass% or less, and even more preferably 2 mass% or less.

[0249] <(H) Optional Additives> The resin composition layer of the resin sheet may contain an optional additive (H) as an optional component. The optional additive (H) as the component (H) does not include those corresponding to the above-mentioned components (A) to (G). The optional additive (H) may include organometallic compounds such as organocopper compounds, organozinc compounds, and organocobalt compounds; colorants such as phthalocyanine blue, phthalocyanine green, iodine green, diazo yellow, crystal violet, titanium oxide, and carbon black; polymerization inhibitors such as hydroquinone, catechol, pyrogallol, and phenothiazine; leveling agents such as silicone-based leveling agents and acrylic polymer-based leveling agents; thickeners such as bentone and montmorillonite; defoamers such as silicone-based defoamers, acrylic defoamers, fluorine-based defoamers, and vinyl resin-based defoamers; ultraviolet absorbers such as benzotriazole-based ultraviolet absorbers; adhesion improvers such as urea silane; triazole-based adhesion imparting agents, tetrazole-based adhesion imparting agents, and triazine-based adhesion imparting agents. antioxidants such as hindered phenol-based antioxidants; fluorescent brightening agents such as stilbene derivatives; surfactants such as fluorine-based surfactants and silicone-based surfactants; flame retardants such as phosphorus-based flame retardants (e.g., phosphate ester compounds, phosphazene compounds, phosphinic acid compounds, red phosphorus), nitrogen-based flame retardants (e.g., melamine sulfate), halogen-based flame retardants, and inorganic flame retardants (e.g., antimony trioxide); dispersants such as phosphate ester-based dispersants, polyoxyalkylene-based dispersants, acetylene-based dispersants, silicone-based dispersants, anionic dispersants, and cationic dispersants; and stabilizers such as borate-based stabilizers, titanate-based stabilizers, aluminate-based stabilizers, zirconate-based stabilizers, isocyanate-based stabilizers, carboxylic acid-based stabilizers, and carboxylic acid anhydride-based stabilizers.

[0250] <(I) Optional Solvent> The resin composition layer of the resin sheet may contain (I) an arbitrary solvent as an arbitrary volatile component. The (I) arbitrary solvent does not include the above-mentioned (B) tetrahydrofuran. As the (I) arbitrary solvent, an organic solvent is usually used. Examples of the organic solvent include ketone-based solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; ester-based solvents such as methyl acetate, ethyl acetate, butyl acetate, isobutyl acetate, isoamyl acetate, methyl propionate, ethyl propionate, and γ-butyrolactone; ether-based solvents such as tetrahydropyran, 1,4-dioxane, diethyl ether, diisopropyl ether, dibutyl ether, diphenyl ether, and anisole; alcohol-based solvents such as methanol, ethanol, propanol, butanol, and ethylene glycol; ester-based solvents such as 2-ethoxyethyl acetate, propylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, ethyl diglycol acetate, γ-butyrolactone, and methyl methoxypropionate. Examples of the solvent include ether ester solvents, ester alcohol solvents such as methyl lactate, ethyl lactate, and methyl 2-hydroxyisobutyrate, ether alcohol solvents such as 2-methoxypropanol, 2-methoxyethanol, 2-ethoxyethanol, propylene glycol monomethyl ether, and diethylene glycol monobutyl ether (butyl carbitol), amide solvents such as N,N-dimethylformamide, N,N-dimethylacetamide, and N-methyl-2-pyrrolidone, sulfoxide solvents such as dimethyl sulfoxide, nitrile solvents such as acetonitrile and propionitrile, aliphatic hydrocarbon solvents such as hexane, cyclopentane, cyclohexane, and methylcyclohexane, and aromatic hydrocarbon solvents such as benzene, toluene, xylene, ethylbenzene, and trimethylbenzene. (I) The optional solvent may be used alone or in combination of two or more.

[0251] The amount of the (I) optional solvent is preferably set so that the amount of the total solvent in the resin composition layer (i.e., the total amount of (B) tetrahydrofuran and (I) optional solvent) falls within a specific range. Specifically, the range of the amount of the total solvent in the resin composition layer is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, and even more preferably 1% by mass or more, and is preferably 20% by mass or less, more preferably 10% by mass or less, and even more preferably 5% by mass or less, relative to 100% by mass of the total amount of the resin composition layer.

[0252] <Biomass ratio in resin composition layer> From the viewpoint of energy saving, cost saving, and promoting sustainability, the biomass ratio of the non-volatile components in the resin composition layer is preferably high. The range of the biomass ratio of the non-volatile components in the resin composition layer is preferably 0.1 mass% or more, more preferably 0.5 mass% or more, even more preferably 1 mass% or more, and particularly preferably 2 mass% or more. The upper limit is preferably 100 mass% or less, but may be 90 mass% or less or 80 mass% or less.

[0253] The biomass ratio of the non-volatile components in the resin composition layer can be calculated using the following formula (M2): However, even if the non-volatile components in the resin composition layer contain components that have been certified by the mass balance method, the mass balance method is not adopted and the biomass ratio is calculated based on the following formula (M2). Biomass ratio (mass%) = (mass of biological components in non-volatile components / mass of non-volatile components) × 100 (M2)

[0254] In addition, the biomass ratio of the resin component in the resin composition layer is preferably high. The range of the biomass ratio of the resin component in the resin composition layer is preferably 0.1% by mass or more, more preferably 1% by mass or more, and particularly preferably 5% by mass or more. The upper limit is preferably 100% by mass or less, but may be 90% by mass or less, 80% by mass or less, or 70% by mass or less.

[0255] The biomass ratio of the resin component in the resin composition layer can be calculated using the following formula (M3): However, even if the resin component in the resin composition layer contains a component that has been certified by the mass balance method, the mass balance method is not adopted and the biomass ratio is calculated based on the following formula (M3). Biomass ratio (mass%) = (mass of biological components in resin component / mass of resin component) × 100 (M3)

[0256] <Thickness of Resin Composition Layer> From the viewpoint of thinning, the thickness of the resin composition layer of the resin sheet is preferably 200 μm or less, more preferably 150 μm or less, and further preferably 100 μm or less. The lower limit of the thickness can be, for example, 1 μm or more, 3 μm or more, 5 μm or more, etc.

[0257] <Characteristics of the cured layer obtained by curing the resin composition layer> A cured layer can be obtained by curing the resin composition layer. Then, an insulating layer can be formed by this cured layer. Usually, heat is applied when curing the resin composition layer, and volatile components such as (B) tetrahydrofuran and (H) any solvent among the components contained in the resin composition layer can be volatilized by the heat during curing. Therefore, the cured layer obtained by curing the resin composition layer can contain non-volatile components such as (A) and (C) to (I) components or reaction products thereof.

[0258] The cured layer obtained by curing the resin composition layer preferably has a small average linear thermal expansion coefficient. The average linear thermal expansion coefficient of the cured layer is preferably 50 ppm / ° C. or less, more preferably 45 ppm / ° C. or less, and even more preferably 40 ppm / ° C. or less. The lower limit may be, for example, 1 ppm / ° C. or more, 5 ppm / ° C. or more, or 10 ppm / ° C. or more.

[0259] The average coefficient of linear thermal expansion of the cured material layer can be measured in the temperature range of 25° C. to 150° C. by thermomechanical analysis using a tensile load method under measurement conditions of a load of 1 g and a heating rate of 5° C. / min. The measurement can be performed on a cured material layer obtained by curing a resin composition layer under curing conditions of 190° C. for 90 minutes. A specific measurement method that can be used is the method described in <Measurement test of average coefficient of linear thermal expansion (CTE) and glass transition temperature Tg> in the examples described later.

[0260] The cured layer obtained by curing the resin composition layer preferably has a low dielectric loss tangent. The range of the dielectric loss tangent of the cured layer is preferably less than 0.015, more preferably less than 0.01, and even more preferably less than 0.005. The lower limit may be, for example, 0.001 or more, 0.002 or more, etc.

[0261] The dielectric loss tangent of the cured material layer can be measured by a cavity resonance perturbation method at a measurement frequency of 5.8 GHz and a measurement temperature of 23° C. The measurement can be performed on a cured material layer obtained by curing a resin composition layer under curing conditions of 190° C. for 90 minutes. A specific measurement method can be the method described in <Dielectric loss tangent measurement test> in the examples described later.

[0262] The cured layer obtained by curing the resin composition layer preferably has a high glass transition temperature. The glass transition temperature of the cured layer is preferably higher than 150° C., more preferably 152° C. or higher, and even more preferably 154° C. or higher. The upper limit may be, for example, 200° C. or lower, 190° C. or lower, or 180° C. or lower.

[0263] The glass transition temperature of the cured material layer can be measured by thermomechanical analysis using a tensile load method under measurement conditions of a load of 1 g and a temperature rise rate of 5°C / min. The measurement can be performed on a cured material layer obtained by curing a resin composition layer under curing conditions of 190°C for 90 minutes. A specific measurement method can be the method described in <Measurement test of average coefficient of linear thermal expansion (CTE) and glass transition temperature Tg> in the examples described later.

[0264] As described above, the cured layer obtained by curing the resin composition layer may contain the non-volatile components of the resin composition layer or their reaction products. Therefore, the cured layer can usually have a biomass ratio in the same range as the range of the biomass ratio of the non-volatile components in the resin composition layer. It is preferable from the viewpoint of promoting sustainability that the cured layer can have such a high biomass ratio.

[0265] <Support> The resin sheet may have a support. When the resin sheet has a support, the above-mentioned resin composition layer is usually formed on this support. Examples of the support include a film of a plastic material, a metal foil, and a release paper, and a film of a plastic material and a metal foil are preferred.

[0266] When a film of a plastic material is used as the support, examples of the plastic material include polyesters such as polyethylene terephthalate (hereinafter sometimes abbreviated as "PET") and polyethylene naphthalate (hereinafter sometimes abbreviated as "PEN"), polycarbonate (hereinafter sometimes abbreviated as "PC"), acrylics such as polymethyl methacrylate (PMMA), cyclic polyolefins, triacetyl cellulose (TAC), polyether sulfide (PES), polyether ketone, polyimide, etc. Among these, polyethylene terephthalate and polyethylene naphthalate are preferred, and inexpensive polyethylene terephthalate is particularly preferred.

[0267] When a metal foil is used as the support, examples of the metal foil include copper foil, aluminum foil, etc., and copper foil is preferred. As the copper foil, a foil made of a single metal, copper, or an alloy of copper and another metal (e.g., tin, chromium, silver, magnesium, nickel, zirconium, silicon, titanium, etc.) may be used.

[0268] The surface of the support that is to be bonded to the resin composition layer may be subjected to a surface treatment such as a matte treatment, a corona treatment, or an antistatic treatment.

[0269] The support may be a support with a release layer having a release layer on the surface to be bonded to the resin composition layer. The release agent used in the release layer of the support with a release layer may be, for example, one or more release agents selected from the group consisting of alkyd-based release agents, polyolefin-based release agents, urethane-based release agents, and silicone-based release agents. The support with a release layer may be a commercially available product, such as "PET501010", "SK-1", "AL-5", and "AL-7" manufactured by Lintec Corporation; "Lumirror T60" manufactured by Toray Industries, Inc.; "Purex" manufactured by Teijin Limited; and "Unipeel" manufactured by Unitika Limited, which are PET films having a release layer mainly composed of a silicone-based release agent or an alkyd resin-based release agent.

[0270] The thickness of the support is not particularly limited, but is preferably 1 μm or more, more preferably 5 μm or more, and even more preferably 10 μm or more, and is preferably 75 μm or less, more preferably 60 μm or less, and even more preferably 50 μm or less. When a support with a release layer is used, it is preferable that the thickness of the entire support with a release layer is in the above range.

[0271] <Optional parts> The resin sheet may include any member other than the resin composition layer and the support, as necessary. For example, the resin sheet may include a protective film for protecting the resin composition layer. The protective film is usually provided on the surface of the resin composition layer that is not bonded to the support (i.e., the surface opposite to the support). The thickness of the protective film is not particularly limited, but is, for example, 1 μm to 40 μm. When the protective film is provided, adhesion of dust and scratches on the surface of the resin composition layer can be suppressed. When the resin sheet has a protective film, the resin sheet can usually be used by peeling off the protective film.

[0272] <Method of manufacturing resin sheet> The above-mentioned resin sheet can be manufactured, for example, by using a resin composition containing (A) a furan-type curable resin, (B) tetrahydrofuran, and (C) an inorganic filler. This resin composition is usually used in the form of a liquid composition in the manufacturing method of a resin sheet. Therefore, hereinafter, the above-mentioned resin composition may be referred to as a "resin varnish". The manufacturing method of a resin sheet using this resin varnish includes a step of applying the resin varnish onto a support, and a step of drying the applied resin varnish to form a resin composition layer.

[0273] The resin varnish contains a furan type curable resin (A). The range of the amount of the furan type curable resin (A) in the resin varnish relative to 100% by mass of the total amount of the resin varnish can be the same as the range of the amount of the furan type curable resin (A) in the resin composition layer relative to 100% by mass of the total amount of the resin composition layer. In general, the amount of the solvent such as tetrahydrofuran (B) is reduced by drying, so the content of the furan type curable resin (A) is relatively increased by drying. Therefore, when a resin varnish containing the furan type curable resin (A) in the above amount is used, the amount of the furan type curable resin (A) in the formed resin composition layer can be within the above-mentioned specific range.

[0274] When the amount of non-volatile components or resin components is used as a standard, the content of the (A) furan type curable resin in the resin varnish is usually the same as the content of the (A) furan type curable resin in the resin composition layer. Therefore, the range of the amount of the (A) furan type curable resin in the resin varnish relative to 100% by mass of the non-volatile components in the resin varnish can be the same as the range of the amount of the (A) furan type curable resin in the resin composition layer relative to 100% by mass of the non-volatile components in the resin composition layer. In addition, the range of the amount of the (A) furan type curable resin in the resin varnish relative to 100% by mass of the resin components in the resin varnish can be the same as the range of the amount of the (A) furan type curable resin in the resin composition layer relative to 100% by mass of the resin components in the resin varnish.

[0275] The resin varnish contains (B) tetrahydrofuran. The amount of (B) tetrahydrofuran in the resin varnish is usually 1% by mass or more, preferably 1.5% by mass or more, and more preferably 2% by mass or more, based on 100% by mass of the total amount of the resin varnish. When the resin composition layer contains such an amount of (B) tetrahydrofuran, the resin composition layer of the resin sheet described above can be smoothly formed. The upper limit is preferably 50% by mass or less, more preferably 40% by mass or less, and even more preferably 30% by mass or less.

[0276] The amount of (B) tetrahydrofuran in the resin varnish is preferably 1 mass% or more, more preferably 5 mass% or more, and even more preferably 10 mass% or more, relative to 100 mass% of all solvents in the resin varnish, and is usually 100 mass% or less, preferably 80 mass% or less, and more preferably 60 mass% or less.

[0277] The range of the amount of (B) tetrahydrofuran in the resin varnish is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 20% by mass or more, based on 100% by mass of (A) furan-type curable resin in the resin varnish. The upper limit can be, for example, 1000% by mass or less, 700% by mass or less, 500% by mass or less, etc.

[0278] The resin varnish contains an inorganic filler (C). Based on the amount of non-volatile components, the content of the inorganic filler (C) in the resin varnish is usually the same as the content of the inorganic filler (C) in the resin composition layer. Therefore, the range of the amount of the inorganic filler (C) in the resin varnish relative to 100% by mass of the non-volatile components in the resin varnish can be the same as the range of the amount of the inorganic filler (C) in the resin composition layer relative to 100% by mass of the non-volatile components in the resin composition layer. In addition, the range of the total amount of the furan-type curable resin (A) and the inorganic filler (C) in the resin varnish relative to 100% by mass of the non-volatile components in the resin varnish can be the same as the range of the total amount of the furan-type curable resin (A) and the inorganic filler (C) in the resin composition layer relative to 100% by mass of the non-volatile components in the resin composition layer.

[0279] The resin varnish may contain an optional curable resin (D) as an optional component. Based on the amount of the non-volatile components or resin components, the content of the optional curable resin (D) in the resin varnish is usually the same as the content of the optional curable resin (D) in the resin composition layer.

[0280] Therefore, the range of the amount of the optional curing resin (D) in the resin varnish relative to 100% by mass of the non-volatile components in the resin varnish can be the same as the range of the amount of the optional curing resin (D) in the resin composition layer relative to 100% by mass of the non-volatile components in the resin composition layer. Also, the range of the amount of the epoxy resin (D-1) in the resin varnish relative to 100% by mass of the non-volatile components in the resin varnish can be the same as the range of the amount of the epoxy resin (D-1) in the resin composition layer relative to 100% by mass of the non-volatile components in the resin composition layer. Furthermore, the range of the amount of the optional curing agent (D-2) in the resin varnish relative to 100% by mass of the non-volatile components in the resin varnish can be the same as the range of the amount of the optional curing agent (D-2) in the resin composition layer relative to 100% by mass of the non-volatile components in the resin composition layer. In addition, the range of the amount of the (D-3) radical polymerizable resin in the resin varnish relative to 100 mass% of the non-volatile components in the resin varnish may be the same as the range of the amount of the (D-3) radical polymerizable resin in the resin composition layer relative to 100 mass% of the non-volatile components in the resin composition layer.

[0281] Furthermore, the range of the amount of the optional curable resin (D) in the resin varnish relative to 100% by mass of the resin components in the resin varnish may be the same as the range of the amount of the optional curable resin (D) in the resin composition layer relative to 100% by mass of the resin components in the resin composition layer. Also, the range of the amount of the epoxy resin (D-1) in the resin varnish relative to 100% by mass of the resin components in the resin varnish may be the same as the range of the amount of the epoxy resin (D-1) in the resin composition layer relative to 100% by mass of the resin components in the resin composition layer. Furthermore, the range of the amount of the optional curing agent (D-2) in the resin varnish relative to 100% by mass of the resin components in the resin varnish may be the same as the range of the amount of the optional curing agent (D-2) in the resin composition layer relative to 100% by mass of the resin components in the resin composition layer. Also, the range of the amount of the radical polymerizable resin (D-3) in the resin varnish relative to 100% by mass of the resin components in the resin varnish may be the same as the range of the amount of the radical polymerizable resin (D-3) in the resin composition layer relative to 100% by mass of the resin components in the resin composition layer.

[0282] The resin varnish may contain a curing catalyst (E) as an optional component. Based on the amount of the non-volatile components or the resin components, the content of the curing catalyst (E) in the resin varnish is usually the same as the content of the curing catalyst (E) in the resin composition layer.

[0283] Therefore, the range of the amount of the (E) curing catalyst in the resin varnish relative to 100% by mass of the non-volatile components in the resin varnish can be the same as the range of the amount of the (E) curing catalyst in the resin composition layer relative to 100% by mass of the non-volatile components in the resin composition layer. Also, the range of the amount of the curing accelerator in the resin varnish relative to 100% by mass of the non-volatile components in the resin varnish can be the same as the range of the amount of the curing accelerator in the resin composition layer relative to 100% by mass of the non-volatile components in the resin composition layer. Furthermore, the range of the amount of the radical polymerization initiator in the resin varnish relative to 100% by mass of the non-volatile components in the resin varnish can be the same as the range of the amount of the radical polymerization initiator in the resin composition layer relative to 100% by mass of the non-volatile components in the resin composition layer.

[0284] In addition, the range of the amount of the (E) curing catalyst in the resin varnish relative to 100% by mass of the resin components in the resin varnish may be the same as the range of the amount of the (E) curing catalyst in the resin composition layer relative to 100% by mass of the resin components in the resin composition layer. In addition, the range of the amount of the curing accelerator in the resin varnish relative to 100% by mass of the resin components in the resin varnish may be the same as the range of the amount of the curing accelerator in the resin composition layer relative to 100% by mass of the resin components in the resin composition layer. Furthermore, the range of the amount of the radical polymerization initiator in the resin varnish relative to 100% by mass of the resin components in the resin varnish may be the same as the range of the amount of the radical polymerization initiator in the resin composition layer relative to 100% by mass of the resin components in the resin composition layer.

[0285] The resin varnish may contain a polymer resin (F) as an optional component. Based on the amount of the non-volatile components or resin components, the content of the polymer resin (F) in the resin varnish is usually the same as the content of the polymer resin (F) in the resin composition layer.

[0286] Therefore, the range of the amount of the (F) polymer resin in the resin varnish relative to 100% by mass of the nonvolatile components in the resin varnish can be the same as the range of the amount of the (F) polymer resin in the resin composition layer relative to 100% by mass of the nonvolatile components in the resin composition layer. Also, the range of the amount of the (F) polymer resin in the resin varnish relative to 100% by mass of the resin components in the resin varnish can be the same as the range of the amount of the (F) polymer resin in the resin composition layer relative to 100% by mass of the resin components in the resin composition layer.

[0287] The resin varnish may contain an organic filler (G) as an optional component. Based on the amount of the non-volatile components or resin components, the content of the organic filler (G) in the resin varnish is usually the same as the content of the organic filler (G) in the resin composition layer.

[0288] Therefore, the range of the amount of the (G) organic filler in the resin varnish relative to 100% by mass of the nonvolatile components in the resin varnish can be the same as the range of the amount of the (G) organic filler in the resin composition layer relative to 100% by mass of the nonvolatile components in the resin composition layer. Also, the range of the amount of the (G) organic filler in the resin varnish relative to 100% by mass of the resin components in the resin varnish can be the same as the range of the amount of the (G) organic filler in the resin composition layer relative to 100% by mass of the resin components in the resin composition layer.

[0289] The resin varnish may contain an optional additive (H) as an optional component. Based on the amount of non-volatile components, the content of the optional additive (H) in the resin varnish is usually the same as the content of the optional additive (H) in the resin composition layer.

[0290] The resin varnish may contain an optional solvent (I) as an optional volatile component. The amount of the optional solvent (I) is preferably set so that the amount of the total solvent in the resin varnish (i.e., the total amount of tetrahydrofuran (B) and the optional solvent (I)) falls within a specific range. Specifically, the range of the amount of the total solvent in the resin varnish is preferably 5% by mass or more, more preferably 10% by mass or more, even more preferably 20% by mass or more, and is preferably 60% by mass or less, more preferably 50% by mass or less, even more preferably 40% by mass or less, based on the total amount of the resin varnish (100% by mass).

[0291] The range of the biomass ratio of the non-volatile components in the resin varnish is usually the same as the range of the biomass ratio of the non-volatile components in the resin composition layer. The biomass ratio of the non-volatile components in the resin varnish can be calculated using formula (M2), just like the biomass ratio of the non-volatile components in the resin composition layer.

[0292] The range of the biomass ratio of the resin component in the resin varnish is usually the same as the range of the biomass ratio of the resin component in the resin composition layer. The biomass ratio of the resin component in the resin varnish can be calculated using formula (M3), like the biomass ratio of the resin component in the resin composition layer.

[0293] The resin varnish can be produced, for example, by mixing components that can be contained in the resin varnish. Thus, the resin varnish can be produced by a production method including a step of mixing (A) a furan-type curable resin, (B) tetrahydrofuran, and (C) an inorganic filler. This production method may include a step of mixing any components such as components (D) to (I). The components (A) to (I) may be mixed partially or entirely at the same time, or may be mixed in order. In addition, the temperature may be appropriately adjusted during the process of adding and mixing each component. For example, heating and / or cooling may be performed temporarily or throughout. In addition, during or after the mixing process, the resin varnish may be stirred or shaken using a stirring device or shaking device such as a mixer. Furthermore, degassing may be performed under low pressure conditions such as under vacuum, as necessary.

[0294] The method for producing a resin sheet shown in this example includes a step of preparing a resin varnish and then applying the resin varnish to a support. The application can be performed using an appropriate application device such as a die coater. By applying the resin varnish, a film of the resin varnish is formed on the support.

[0295] The method for producing a resin sheet shown in this example includes a step of applying a resin varnish and then drying the applied resin varnish to form a resin composition layer. Drying may be performed by heating, blowing hot air, or other methods. Drying conditions are set so as to obtain the resin composition layer according to the above-mentioned embodiment. Although they may vary depending on the composition and boiling point of the solvent of the resin varnish, for example, drying conditions may be set so as to form a resin composition layer containing the amount of (B) tetrahydrofuran in the above-mentioned range within a drying temperature range of 50°C to 150°C and a drying time range of 2 minutes to 10 minutes.

[0296] The method for producing a resin sheet may further include any step in combination with the above-mentioned steps. For example, the method for producing a resin sheet may include a step of laminating a protective film to the resin composition layer. In addition, for example, the method for producing a resin sheet may include a step of winding up the produced resin sheet into a roll and recovering it.

[0297] <Circuit board> The circuit board according to one embodiment of the present invention includes a cured layer obtained by curing the above-mentioned resin composition layer. This cured layer can form an insulating layer of the circuit board. By forming an insulating layer as a cured layer using the above-mentioned resin sheet, unevenness in the insulating layer can be suppressed.

[0298] The thickness range of the insulating layer is not particularly limited, and may be, for example, the same as the thickness range of the resin composition layer provided in the resin sheet.

[0299] The insulating layer may preferably have a small average linear thermal expansion coefficient. The range of the average linear thermal expansion coefficient of the insulating layer may be the same as the range of the average linear thermal expansion coefficient of the cured layer obtained by curing the resin composition layer. The average linear thermal expansion coefficient of the insulating layer may be measured by the same method as the method for measuring the average linear thermal expansion coefficient of the cured layer.

[0300] The insulating layer may preferably have a low dielectric tangent. The range of the dielectric tangent of the insulating layer may be the same as the range of the dielectric tangent of the cured layer obtained by curing the resin composition layer. The dielectric tangent of the insulating layer may be measured by the same method as the method for measuring the dielectric tangent of the cured layer.

[0301] The insulating layer may preferably have a high glass transition temperature. The glass transition temperature range of the insulating layer may be the same as the glass transition temperature range of the cured layer obtained by curing the resin composition layer. The glass transition temperature of the insulating layer may be measured by the same method as the method for measuring the glass transition temperature of the cured layer.

[0302] The insulating layer can preferably have a high biomass ratio. Specifically, the insulating layer preferably has a biomass ratio in the same range as the range of the biomass ratio of the non-volatile components in the resin composition layer. It is preferable from the viewpoint of promoting sustainability that the insulating layer can have such a high biomass ratio.

[0303] Preferably, the circuit board includes an inner layer substrate and the insulating layer is provided on the inner layer substrate. The circuit board may also include a conductor layer. For example, the circuit board may include a conductor layer on an insulating layer. Such a circuit board may include, for example, A step (I) of laminating a resin sheet and an inner layer substrate so that the resin composition layer and the inner layer substrate are bonded to each other; A step (II) of curing the resin composition layer; The composition can be produced by a production method including the steps of:

[0304] The term "inner layer board" refers to a member that serves as the base material of a circuit board, and examples thereof include a glass epoxy board, a metal board, a polyester board, a polyimide board, a BT resin board, and a thermosetting polyphenylene ether board. The inner layer board may have a conductor layer on one or both sides. The conductor layer of the inner layer board may be patterned. An inner layer board having a conductor layer (circuit) formed on one or both sides of the board may be called an "inner layer circuit board". In addition, an intermediate product on which an insulating layer and / or a conductor layer is to be further formed during the manufacture of a circuit board is also included in the term "inner layer board". An inner layer board with a built-in component may also be used.

[0305] In step (I), a resin composition layer is formed on the inner layer substrate by laminating the resin sheet and the inner layer substrate. The resin sheet and the inner layer substrate are laminated so that the resin composition layer of the resin sheet and the inner layer substrate are bonded. This lamination may be performed, for example, by thermocompression bonding the resin sheet to the inner layer substrate from the support side. Examples of the member for thermocompression bonding the resin sheet to the inner layer substrate (hereinafter also referred to as the "thermocompression bonding member") include a heated metal plate (such as a SUS plate) or a metal roll (such as a SUS roll). It is preferable to press the thermocompression bonding member through an elastic material such as heat-resistant rubber so that the resin sheet can sufficiently follow the surface irregularities of the inner layer substrate, rather than directly pressing the resin sheet.

[0306] The lamination of the inner layer substrate and the resin sheet may be performed by a vacuum lamination method. In the vacuum lamination method, the thermocompression temperature is preferably in the range of 60°C to 160°C, more preferably in the range of 80°C to 140°C, the thermocompression pressure is preferably in the range of 0.098MPa to 1.77MPa, more preferably in the range of 0.29MPa to 1.47MPa, and the thermocompression time is preferably in the range of 20 seconds to 400 seconds, more preferably in the range of 30 seconds to 300 seconds. The lamination is preferably performed under reduced pressure conditions of 26.7hPa or less.

[0307] The lamination may be performed by a commercially available vacuum laminator, such as a vacuum pressure laminator manufactured by Meiki Seisakusho Co., Ltd., a vacuum applicator manufactured by Nikko Materials Co., Ltd., or a batch type vacuum pressure laminator.

[0308] The manufacturing method of the circuit board may include performing a smoothing treatment of the resin sheet after lamination under normal pressure (atmospheric pressure), for example, by pressing a thermocompression member from the support side. The pressing conditions for the smoothing treatment may be the same as the conditions for the thermocompression bonding of the lamination. The smoothing treatment may be performed by a commercially available laminator. The lamination and the smoothing treatment may be performed successively using the commercially available vacuum laminator.

[0309] The method for producing a circuit board according to this embodiment includes a step (II) of curing the resin composition layer after the step (I). By curing the resin composition layer in the step (II), an insulating layer can be formed as a cured layer of the resin composition layer.

[0310] The resin composition layer can be cured by an appropriate method depending on the type of the curable resin, such as (A) a furan-type curable resin and (D) any curable resin. For example, when the curable resin includes a thermosetting resin, the resin composition layer may be cured by heating. Also, for example, when the curable resin includes a photocurable resin, the resin composition layer may be cured by light irradiation. In a preferred embodiment, since the curable resin includes a thermosetting resin, the step (II) cures the resin composition layer by heating.

[0311] The thermal curing conditions of the resin composition layer may vary depending on the composition of the resin composition. For example, the curing temperature is preferably 120° C. to 240° C., more preferably 150° C. to 220° C., and even more preferably 170° C. to 210° C. The curing time is preferably 5 minutes to 120 minutes, more preferably 10 minutes to 100 minutes, and even more preferably 15 minutes to 100 minutes.

[0312] The method for producing a circuit board may include preheating the resin composition layer at a temperature lower than the curing temperature before the thermal curing of the resin composition layer. For example, prior to thermal curing of the resin composition layer, the resin composition layer may be preheated for usually 5 minutes or more, preferably 5 minutes to 150 minutes, more preferably 15 minutes to 120 minutes, and even more preferably 15 minutes to 100 minutes at a temperature of usually 50°C to 150°C, preferably 60°C to 140°C, and more preferably 70°C to 130°C. The preheating is usually performed after step (I). In addition, when a smoothing treatment is performed after lamination of the inner layer substrate and the resin sheet, the preheating may be performed after the smoothing treatment.

[0313] When a resin sheet having a support is used, the method for producing a circuit board may include a step of peeling off the support after laminating the inner layer board and the resin sheet. The peeling off of the support may be performed between step (I) and step (II), or after step (II). In addition, when the method for producing a circuit board includes step (III) of forming holes in the insulating layer, step (IV) of performing a roughening treatment on the insulating layer, and step (V) of forming a conductor layer as described below, the peeling off of the support may be performed between step (II) and step (III), between step (III) and step (IV), or between step (IV) and step (V).

[0314] The method for producing a circuit board may include a step (III) of forming holes such as via holes and through holes in the insulating layer after the step (II). The method for forming the holes may be selected depending on factors such as the composition of the resin composition layer used to form the insulating layer. For example, the holes may be formed by processing methods such as drilling, laser processing, and plasma processing, among which laser processing is preferred. For example, the holes may be formed by irradiating the insulating layer with laser light after peeling off the support, or the holes may be formed by irradiating the insulating layer with laser light through the support. The size and shape of the holes may be appropriately determined depending on the design of the circuit board.

[0315] The method for manufacturing a circuit board may include a step (IV) of performing a roughening treatment on the insulating layer. The roughening treatment can roughen the surface of the insulating layer. In addition, the roughening treatment can remove smears (resin residues) from the insulating layer. Therefore, this roughening treatment is sometimes called a "desmear treatment." For example, when a hole is formed in the step (III), a smear may be formed in the hole, so it is preferable to perform the roughening treatment in the step (IV) after the step (III) to remove the smear.

[0316] The procedure and conditions of the roughening treatment are not particularly limited, and known procedures and conditions that are usually used when forming an insulating layer of a circuit board can be adopted. For example, the roughening treatment may be performed by subjecting the insulating layer to a swelling treatment using a swelling liquid, an oxidation treatment using an oxidizing agent, and a neutralization treatment using a neutralizing liquid in this order.

[0317] Examples of the swelling liquid used in the roughening treatment include an alkaline solution and a surfactant solution, and an alkaline solution is preferred. As the alkaline solution, a sodium hydroxide solution and a potassium hydroxide solution are more preferred. Examples of commercially available swelling liquids include "Swelling Dip Securigans P" and "Swelling Dip Securigans SBU" manufactured by Atotech Japan. The swelling treatment using a swelling liquid can be performed by immersing the insulating layer in a swelling liquid at 30°C to 90°C for 1 to 20 minutes. From the viewpoint of suppressing the swelling of the resin of the insulating layer to an appropriate level, it is preferred to immerse the insulating layer in a swelling liquid at 40°C to 80°C for 5 to 15 minutes.

[0318] An example of an oxidizing agent used in the roughening treatment is an alkaline permanganate solution in which potassium permanganate or sodium permanganate is dissolved in an aqueous solution of sodium hydroxide. The oxidation treatment using an oxidizing agent such as an alkaline permanganate solution is preferably performed by immersing the insulating layer in an oxidizing agent solution heated to 60°C to 100°C for 10 minutes to 30 minutes. The concentration of permanganate in the alkaline permanganate solution is preferably 5% by mass to 10% by mass. Examples of commercially available oxidizing agents include alkaline permanganate solutions such as "Concentrate Compact CP" and "Dosing Solution Securigans P" manufactured by Atotech Japan.

[0319] The neutralizing solution used in the roughening treatment is preferably an acidic aqueous solution, and a commercially available product is, for example, "Reduction Solution Securigant P" manufactured by Atotech Japan. The neutralizing treatment with the neutralizing solution can be carried out by immersing the treated surface that has been oxidized with an oxidizing agent in the neutralizing solution at 30°C to 80°C for 5 to 30 minutes. From the viewpoint of workability, a method in which the object that has been oxidized with an oxidizing agent is immersed in the neutralizing solution at 40°C to 70°C for 5 to 20 minutes is preferred.

[0320] The method for producing a circuit board may include a step (V) of forming a conductor layer on an insulating layer. When the method for producing a circuit board includes the steps (III) or (IV), the step (V) of forming a conductor layer is usually preferably carried out after the steps (III) and (IV).

[0321] The conductor material used for the conductor layer is not particularly limited. In a preferred embodiment, the conductor layer contains one or more metals selected from the group consisting of gold, platinum, palladium, silver, copper, aluminum, cobalt, chromium, zinc, nickel, titanium, tungsten, iron, tin and indium. The conductor layer may be a single metal layer or an alloy layer. Examples of the alloy layer include layers formed from an alloy of two or more metals selected from the above group (e.g., nickel-chromium alloy, copper-nickel alloy and copper-titanium alloy). Among them, from the viewpoints of versatility of conductor layer formation, cost, ease of patterning, etc., a single metal layer of chromium, nickel, titanium, aluminum, zinc, gold, palladium, silver or copper, or an alloy layer of nickel-chromium alloy, copper-nickel alloy, copper-titanium alloy is preferred, a single metal layer of chromium, nickel, titanium, aluminum, zinc, gold, palladium, silver or copper, or an alloy layer of nickel-chromium alloy is more preferred, and a single metal layer of copper is even more preferred.

[0322] The conductor layer may have a single-layer structure, or a multi-layer structure including two or more single metal layers or alloy layers made of different kinds of metals or alloys. When the conductor layer has a multi-layer structure, the layer in contact with the insulating layer is preferably a single metal layer of chromium, zinc or titanium, or an alloy layer of a nickel-chromium alloy.

[0323] The thickness of the conductor layer depends on the design of the circuit board, but is preferably 3 μm to 35 μm, and more preferably 5 μm to 30 μm.

[0324] The conductor layer may be formed by plating. For example, a plating layer (a plating seed layer) may be formed on the surface of the insulating layer by a conventionally known technique such as a semi-additive method or a full-additive method to form a conductor layer having a desired wiring pattern. From the viewpoint of manufacturing simplicity, the semi-additive method is preferred. Hereinafter, an example of forming the conductor layer by the semi-additive method is shown.

[0325] First, an electroless plating layer (a plating seed layer) is formed on the surface of the insulating layer by electroless plating. Next, a mask pattern is formed on the formed electroless plating layer to expose a part 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. Thereafter, the unnecessary electroless plating layer is removed by etching to form a conductor layer having a desired wiring pattern.

[0326] As another example, the conductor layer may be formed using a metal foil. When forming the conductor layer using a 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 a metal foil is laminated on the surface of the exposed resin composition layer. The lamination of the resin composition layer and the metal foil may be performed by a vacuum lamination method. The lamination conditions may be the same as those described for step (I). Next, step (II) is performed to form an insulating layer. Thereafter, using the metal foil on the insulating layer, a conductor layer having a desired wiring pattern can be formed by a known technique such as a subtractive method or a modified semi-additive method. The metal foil can be manufactured by a known method such as an electrolytic method or a rolling method. Examples of commercially available metal foils include HLP foil, JXUT-III foil manufactured by JX Metals, 3EC-III foil, TP-III foil manufactured by Mitsui Mining & Smelting Co., Ltd., and the like.

[0327] When a conductor layer is formed on an insulating layer, the method for manufacturing a circuit board may include performing an annealing treatment after the formation of the conductor layer. The annealing treatment can increase the adhesion between the insulating layer and the conductor layer. The annealing treatment can be performed, for example, by heating at 150°C to 210°C for 20 minutes to 180 minutes.

[0328] In the method for producing a circuit board, each of the above steps may be performed only once or may be repeated two or more times. For example, steps (I) to (V) may be performed repeatedly to form a circuit board having a multilayer structure, such as a multilayer printed wiring board having a plurality of insulating layers and conductor layers.

[0329] The manufacturing method of the circuit board may further include any step in combination with the above-mentioned steps. For example, the manufacturing method of the circuit board may include a step of providing a semiconductor chip so as to be bonded to the conductor layer. As a specific example, when manufacturing a circuit board for a semiconductor chip package having a semiconductor chip, the manufacturing method of the circuit board may include a step of providing a semiconductor chip. The semiconductor chip may adopt appropriate conditions that allow the terminal electrodes of the semiconductor chip and the conductor layer formed on the insulating layer to be conductively connected. For example, conditions used in flip chip mounting may be adopted. The semiconductor chip may be bonded via an insulating adhesive or by reflow. Furthermore, if necessary, the provided semiconductor chip may be filled with a mold underfill material. The manufacturing method of the circuit board may also include, for example, a step of forming a sealing layer, a step of forming a solder resist layer, a step of dicing the manufactured circuit board to separate it into individual pieces, and the like.

[0330] Examples of the circuit board include, for example, a printed wiring board and a semiconductor chip package. Examples of the semiconductor chip package include an FC-CSP, a MIS-BGA package, an ETS-BGA package, a Fan-out type WLP (Wafer Level Package), a Fan-in type WLP, a Fan-out type PLP (Panel Level Package), and a Fan-in type PLP. In these semiconductor chip packages, it is preferable to form a redistribution layer-forming layer with an insulating layer obtained by curing the above-described resin composition layer. However, the circuit board is not limited to those exemplified here.

[0331] <Semiconductor device> The above-described circuit board can be used in the manufacture of a semiconductor device. The semiconductor device includes the above-described circuit board. Examples of the semiconductor device include various semiconductor devices used in electric products (for example, computers, mobile phones, smartphones, tablet devices, wearable devices, digital cameras, medical devices, and televisions, etc.) and vehicles (for example, motorcycles, automobiles, trains, ships, and airplanes, etc.).

Example

[0332] Hereinafter, the present invention will be specifically described with reference to examples. However, the present invention is not limited to these examples. In the following description, "parts" and "%" representing amounts mean "parts by mass" and "mass%" respectively, unless otherwise specified. Also, the temperature conditions and pressure conditions in the absence of special designation were room temperature (23 ° C) and atmospheric pressure (1 atm).

[0333] <Synthesis Example 1: Synthesis of a furan skeleton-containing polyester resin (1)> In a 0.3-liter four-necked round flask equipped with a stirrer, a thermometer, a dropping funnel, and a nitrogen gas inlet, 11.4 g of dicyclopentadiene-phenol polyadduct (JFE Chemical Corporation's "J-DPP85", hydroxyl equivalent 165 g / eq.), 4.98 g of 1-naphthol, 10.0 g of 2,5-furandicarboxylic acid chloride, 0.026 g of tetra-n-butylammonium bromide, and 50 g of toluene were added, and the mixture was stirred while blowing in nitrogen gas and heated to 30°C to dissolve. 16.6 g of 25% aqueous caustic soda solution was added dropwise while being careful not to generate heat so that the temperature would eventually rise to 60°C. The time required for the dropwise addition was 15 minutes. After stirring at 60°C for another hour, 25 g of distilled water was added and stirred, and the aqueous layer was discarded. The organic layer was washed three times in the same manner. The organic layer was dried over sodium sulfate, the drying agent was filtered off, and then a part of the solvent was distilled off from the obtained solution to obtain 24.7 g of the target furan skeleton-containing polyester resin (1) containing 45 mass% toluene (toluene solution having an active group equivalent of about 215 g / eq., a biomass ratio of 28.4 mass%, and a non-volatile component ratio of 55%).

[0334] [ka]

[0335] <Synthesis Example 2: Synthesis of Furan Skeleton-Containing Polyester Resin (2)> In a 0.3-liter four-necked round flask equipped with a stirrer, a thermometer, a dropping funnel, and a nitrogen gas inlet, 20.0 g of bisphenol A (hydroxyl equivalent: 114 g / eq.), 8.1 g of phenol, 25.0 g of 2,5-furandicarboxylic acid chloride, 0.053 g of tetra-n-butylammonium bromide, and 70 g of toluene were added, and the mixture was stirred while blowing in nitrogen gas and heated to 30°C to dissolve. 48 g of 25% aqueous caustic soda solution was added dropwise while being careful not to generate heat so that the temperature would eventually rise to 60°C. The time required for the dropwise addition was 15 minutes. After stirring at 60°C for another hour, 25 g of distilled water was added and stirred, and the aqueous layer was discarded. The organic layer was washed three times in the same manner. The organic layer was dried over sodium sulfate, the drying agent was filtered off, and then a part of the solvent was distilled off from the obtained solution to obtain the target furan skeleton-containing polyester resin (2) having a solid content of 45 mass% (active group equivalent weight: about 153 g / eq., biomass ratio: >99 mass%, non-volatile content: 45%).

[0336] [ka]

[0337] <Synthesis Example 3: Synthesis of furan skeleton-containing polyester resin (3)> In Synthesis Example 1, 4.98 g of 1-naphthol was changed to 8.0 g of camphene-modified phenol (Yasuhara Chemical Co., Ltd.'s "YS Resin CP", hydroxyl equivalent 220 g / eq.). In addition, 11.4 g of dicyclopentadiene-phenol polyadduct (JFE Chemical Co., Ltd.'s "J-DPP85", hydroxyl equivalent 165 g / eq.) was changed to 7.9 g of bisphenol A (hydroxyl equivalent 114 g / eq.). Except for the above, the same procedure as in Synthesis Example 1 was followed to obtain the target furan skeleton-containing polyester resin (3) (active group equivalent about 225 g / eq., biomass ratio 88 mass%, non-volatile component ratio 55%).

[0338] [ka]

[0339] <Synthesis Example 4: Synthesis of furan skeleton-containing polyester resin (4)> In Synthesis Example 1, 4.98 g of 1-naphthol was changed to 3.3 g of phenol. Also, 11.4 g of dicyclopentadiene-phenol polyadduct ("J-DPP85" manufactured by JFE Chemical Corporation, hydroxyl group equivalent 165 g / eq.) was changed to 14 g of benzyl-modified bisphenol A (d and e are 1≦d+e≦4). A furan skeleton-containing polyester resin (4) (active group equivalent of about 217 g / eq., biomass ratio of 71 mass%, non-volatile component ratio of 46% in toluene solution) was obtained in the same manner as in Synthesis Example 1 except for the above matters (wherein d and e represent numbers in the range of 1≦d+e≦4).

[0340] [ka]

[0341] <Synthesis Example 5: Synthesis of poly(5-methoxymethyl-2-vinylfuran) (PMMVF)> According to the method described in Example 1 of JP2010-43203A, poly(5-methoxymethyl-2-vinylfuran) (PMMVF) represented by the following formula (5) was obtained.

[0342] [ka]

[0343] <Synthesis Example 6: Synthesis of polycarbosilane> According to the method described in Example 2-3 of WO 2023 / 100914, polycarbosilane represented by the following formula (6) was obtained.

[0344] [ka]

[0345] <Example 1> 15 parts of bisphenol A type epoxy resin (Mitsubishi Chemical Corporation "828EL", epoxy equivalent about 180g / eq., biomass ratio 0 mass%), 20 parts of biphenyl type epoxy resin (Nippon Kayaku Co., Ltd. "NC3000L", epoxy equivalent about 269g / eq., biomass ratio 0 mass%), 20 parts of naphthalene type epoxy resin (Nippon Steel Chemical & Material Co., Ltd. "ESN475V", epoxy equivalent about 332g / eq., biomass ratio 0 mass%) were added with 50 parts of methyl ethyl ketone (MEK) and 10 parts of tetrahydrofuran (THF) as dilution solvents, and heated and dissolved with stirring. This was cooled to room temperature to prepare an epoxy resin dissolved composition.

[0346] To this epoxy resin solution composition, 3 parts of a naphthol-type curing agent ("SN-485" manufactured by Nippon Steel Chemical & Material Co., Ltd., hydroxyl group equivalent of about 205 g / eq., biomass ratio of 0 mass%), 40 parts of the furan skeleton-containing polyester resin (1) obtained in Synthesis Example 1 (toluene solution having active group equivalent of about 215 g / eq., biomass ratio of 28.4 mass%, non-volatile component ratio of 55%), and an amine-based curing accelerator (4-dimethylaminopyridine (DMAP), biomass ratio of 0 mass%, solid content of 5 mass%) were added. A resin varnish was produced by mixing 4 parts of MEK solution of 100 parts of spherical silica (Admatechs' SO-C2, average particle size 0.5 μm, biomass ratio 0 mass%) that had been surface-treated with a silane coupling agent (Shin-Etsu Chemical's KBM-573), and 8 parts of phenoxy resin (Mitsubishi Chemical's YX7553BH30, biomass ratio 0 mass%, 1:1 solution of MEK and cyclohexanone with a non-volatile content of 30 mass%) and dispersing the mixture uniformly in a high-speed rotating mixer.

[0347] A polyethylene terephthalate film ("AL5" manufactured by Lintec Corporation, thickness 38 μm) having a release-treated release surface was prepared as a support. A resin varnish was uniformly applied to the release surface of the support so that the thickness of the resin composition layer was 40 μm, and the resin sheet was produced by drying at 80°C to 120°C (average 100°C) for 5 minutes.

[0348] <Example 2> A resin varnish and a resin sheet were produced in the same manner as in Example 1, except that the drying time after application of the resin varnish was changed to 7 minutes.

[0349] <Example 3> 15 parts of bisphenol A type epoxy resin (Mitsubishi Chemical Corporation "828EL", epoxy equivalent about 180g / eq., biomass ratio 0 mass%), 20 parts of biphenyl type epoxy resin (Nippon Kayaku Co., Ltd. "NC3000L", epoxy equivalent about 269g / eq., biomass ratio 0 mass%), 20 parts of naphthalene type epoxy resin (Nippon Steel Chemical & Material Co., Ltd. "ESN475V", epoxy equivalent about 332g / eq., biomass ratio 0 mass%) were added with 35 parts of methyl ethyl ketone (MEK) and 10 parts of tetrahydrofuran (THF) as dilution solvents, and heated and dissolved with stirring. This was cooled to room temperature to prepare an epoxy resin dissolved composition.

[0350] To this epoxy resin solution, 5 parts of a triazine skeleton-containing phenol-based curing agent (DIC Corporation's "LA-3018-50P", 2-methoxypropanol solution with active group equivalent of about 151 g / eq., biomass ratio of 0 mass%, and non-volatile content of 50%), 10 parts of the furan skeleton-containing polyester resin (1) obtained in Synthesis Example 1 (toluene solution with active group equivalent of about 215 g / eq., biomass ratio of 28.4 mass%, and non-volatile content of 55%), 25 parts of an active ester compound (DIC Corporation's "HPC-8000-65T", toluene solution with active group equivalent of about 223 g / eq., biomass ratio of 0 mass%, and non-volatile content of 65%), 25 parts of an amine-based curing accelerator (4-dimethylaminopyridine (DMAP), biomass ratio of 0 mass%, MEK with a solid content of 5 mass%), and 10 parts of a benzene ring-type polyester resin (1) (DIC Corporation's "HPC-8000-65T", toluene solution with active group equivalent of about 223 g / eq., biomass ratio of 0 mass%, and non-volatile content of 65%), ... solution), 2 parts of an imidazole curing accelerator ("1B2PZ" manufactured by Shikoku Chemical Industry Co., Ltd., 1-benzyl-2-phenylimidazole, biomass ratio 0 mass%, MEK solution with solid content 10 mass%), 90 parts of spherical silica ("UFP-30" manufactured by Denka Co., Ltd., average particle size 0.3 μm, biomass ratio 0%) surface-treated with a silane coupling agent ("KBM-573" manufactured by Shin-Etsu Chemical Co., Ltd.), 12 parts of a phenoxy resin ("YX7553BH30" manufactured by Mitsubishi Chemical Corporation, biomass ratio 0 mass%, 1:1 solution of MEK and cyclohexanone with non-volatile content of 30 mass%), and 1 part of rubber particles ("Staphyloid AC3816N" manufactured by Aica Kogyo Co., Ltd., biomass ratio 0 mass%) were mixed and uniformly dispersed in a high-speed rotating mixer to produce a resin varnish.

[0351] A resin varnish was uniformly applied to the release surface of a support similar to that in Example 1 so that the resin composition layer had a thickness of 40 μm, and then dried at 80°C to 120°C (average 100°C) for 5 minutes to produce a resin sheet.

[0352] <Example 4> In Example 1, 1) The amount of the furan skeleton-containing polyester resin (1) obtained in Synthesis Example 1 (a toluene solution having an active group equivalent of about 215 g / eq., a biomass ratio of 28.4% by mass, and a non-volatile component ratio of 55%) was changed from 40 parts to 20 parts, 2) 24 parts of the furan skeleton-containing polyester resin (2) obtained in Synthesis Example 2 (toluene solution having an active group equivalent of about 153 g / eq., a biomass ratio of >99% by mass, and a non-volatile component ratio of 45%) was added to a resin varnish, 3) 3 parts of naphthol-type hardener (Nippon Steel Chemical & Material Co., Ltd. "SN-485", hydroxyl group equivalent of approximately 205 g / eq., biomass ratio of 0 mass%) was changed to 5 parts of triazine skeleton-containing phenol-based hardener (DIC Corporation "LA-3018-50P", active group equivalent of approximately 151 g / eq., biomass ratio of 0 mass%, non-volatile component ratio of 50% in 2-methoxypropanol solution), 4) The amount of tetrahydrofuran (THF) as a diluting solvent was changed from 10 parts to 40 parts. 5) The dilution solvent was changed from 50 parts of methyl ethyl ketone (MEK) to 20 parts of toluene. A resin varnish and a resin sheet were produced in the same manner as in Example 1 except for the above.

[0353] <Example 5> In Example 4, 1) 24 parts of the furan skeleton-containing polyester resin (2) obtained in Synthesis Example 2 (a toluene solution having an active group equivalent of about 153 g / eq., a biomass ratio of >99% by mass, and a non-volatile content of 45%) was changed to 20 parts of the furan skeleton-containing polyester resin (3) obtained in Synthesis Example 3 (a toluene solution having an active group equivalent of about 225 g / eq., a biomass ratio of 88% by mass, and a non-volatile content of 55%), 2) 2 parts of a polyimide compound containing a maleimide group at its end (Designer Molecules Inc.'s "BMI-1500", biomass ratio 0% by mass) was added to a resin varnish, 3) The amount of tetrahydrofuran (THF) as a dilution solvent was changed from 40 parts to 20 parts. 4) The amount of toluene used as a dilution solvent was changed from 20 parts to 40 parts. A resin varnish and a resin sheet were prepared in the same manner as in Example 4 except for the above.

[0354] <Example 6> 5 parts of bisphenol A type epoxy resin (Mitsubishi Chemical Corporation "828EL", epoxy equivalent about 180g / eq., biomass ratio 0 mass%), 20 parts of biphenyl type epoxy resin (Nippon Kayaku Co., Ltd. "NC3000L", epoxy equivalent about 269g / eq., biomass ratio 0 mass%), 10 parts of bixylenol type epoxy resin (Mitsubishi Chemical Corporation "YX4000HK", epoxy equivalent about 185g / eq., biomass ratio 0 mass%), 20 parts of dicyclopentadiene type epoxy resin (DIC Corporation "HP7200HH", epoxy equivalent about 283g / eq., biomass ratio 0 mass%) were added with 40 parts of toluene and 20 parts of tetrahydrofuran (THF) as dilution solvent, and heated and dissolved with stirring. This was cooled to room temperature to prepare an epoxy resin dissolved composition.

[0355] To this epoxy resin solution, 5 parts of a triazine skeleton-containing phenolic curing agent (DIC Corporation's "LA-3018-50P", 2-methoxypropanol solution with active group equivalent of about 151 g / eq., biomass ratio of 0 mass%, and non-volatile content of 50%), 20 parts of the furan skeleton-containing polyester resin (1) obtained in Synthesis Example 1 (toluene solution with active group equivalent of about 215 g / eq., biomass ratio of 28.4 mass%, and non-volatile content of 55%), 24 parts of the furan skeleton-containing polyester resin (4) obtained in Synthesis Example 4 (toluene solution with active group equivalent of about 217 g / eq., biomass ratio of 71 mass%, and non-volatile content of 46%), and 10 parts of the furan skeleton-containing polyester resin (5) obtained in Synthesis Example 5 (toluene solution with active group equivalent of about 217 g / eq., biomass ratio of 71 mass%, and non-volatile content of 46%) were added. 200 parts of spherical silica ("SO-C2" manufactured by Admatechs Co., Ltd., average particle size 0.5 μm, biomass ratio 0 mass%) surface-treated with a silane coupling agent ("KBM-573" manufactured by Shin-Etsu Chemical Co., Ltd.), 8 parts of phenoxy resin ("YX7553BH30" manufactured by Mitsubishi Chemical Co., Ltd., 1:1 solution of MEK and cyclohexanone with a biomass ratio of 0 mass% and non-volatile content of 30 mass%), and 3 parts of vinylbenzyl-modified polyphenylene ether ("OPE-2St 2200" manufactured by Mitsubishi Gas Chemical Co., Ltd., toluene solution with a biomass ratio of 0 mass% and non-volatile content of 65%) were mixed and uniformly dispersed in a high-speed rotating mixer to produce a resin varnish.

[0356] A resin varnish was uniformly applied to the release surface of a support similar to that in Example 1 so that the resin composition layer had a thickness of 40 μm, and then dried at 80°C to 120°C (average 100°C) for 5 minutes to produce a resin sheet.

[0357] <Example 7> In Example 1, 1) The amount of the furan skeleton-containing polyester resin (1) obtained in Synthesis Example 1 (a toluene solution having an active group equivalent of about 215 g / eq., a biomass ratio of 28.4% by mass, and a non-volatile component ratio of 55%) was changed from 40 parts to 30 parts, 2) 5 parts of an active ester compound containing a furan skeleton ("BPTMC-FE" manufactured by Honshu Chemical Industry Co., Ltd., active ester group equivalent weight approximately 249 g / eq., biomass ratio 32% by mass) was added to a resin varnish; 3) The amount of tetrahydrofuran (THF) as a dilution solvent was changed from 10 parts to 40 parts. 4) The amount of methyl ethyl ketone (MEK) used as a dilution solvent was changed from 50 parts to 20 parts. A resin varnish and a resin sheet were produced in the same manner as in Example 1 except for the above.

[0358] <Example 8> In Example 1, 1) The amount of the furan skeleton-containing polyester resin (1) obtained in Synthesis Example 1 (a toluene solution having an active group equivalent of about 215 g / eq., a biomass ratio of 28.4% by mass, and a non-volatile component ratio of 55%) was changed from 40 parts to 30 parts, 2) 5 parts of an active ester compound containing a furan skeleton ("BP-FE" manufactured by Honshu Chemical Industry Co., Ltd., active ester group equivalent weight approximately 187 g / eq., biomass ratio 45% by mass) was added to a resin varnish; 3) The amount of tetrahydrofuran (THF) as a dilution solvent was changed from 10 parts to 40 parts. 4) The amount of methyl ethyl ketone (MEK) used as a dilution solvent was changed from 50 parts to 20 parts. A resin varnish and a resin sheet were produced in the same manner as in Example 1 except for the above.

[0359] <Example 9> In Example 1, 1) The amount of the furan skeleton-containing polyester resin (1) obtained in Synthesis Example 1 (a toluene solution having an active group equivalent of about 215 g / eq., a biomass ratio of 28.4% by mass, and a non-volatile component ratio of 55%) was changed from 40 parts to 30 parts, 2) 5 parts of an active ester compound containing a furan skeleton ("TMPBP-FE" manufactured by Honshu Chemical Industry Co., Ltd., active ester group equivalent weight approximately 217 g / eq., biomass ratio 36% by mass) was added to a resin varnish; 3) The amount of tetrahydrofuran (THF) as a dilution solvent was changed from 10 parts to 40 parts. 4) The amount of methyl ethyl ketone (MEK) used as a dilution solvent was changed from 50 parts to 20 parts. A resin varnish and a resin sheet were produced in the same manner as in Example 1 except for the above.

[0360] <Example 10> 5 parts of bisphenol A type epoxy resin (Mitsubishi Chemical Corporation "828EL", epoxy equivalent about 180g / eq., biomass ratio 0 mass%), 10 parts of biphenyl type epoxy resin (Nippon Kayaku Co., Ltd. "NC3000L", epoxy equivalent about 269g / eq., biomass ratio 0 mass%), 20 parts of naphthalene type epoxy resin (Nippon Steel Chemical & Material Co., Ltd. "ESN475V", epoxy equivalent about 332g / eq., biomass ratio 0 mass%) were added with 50 parts of methyl ethyl ketone (MEK) and 10 parts of tetrahydrofuran (THF) as dilution solvents, and heated and dissolved with stirring. This was cooled to room temperature to prepare an epoxy resin dissolved composition.

[0361] This epoxy resin solution composition was mixed with 70 parts of the furan skeleton-containing polyester resin (1) obtained in Synthesis Example 1 (toluene solution with active group equivalent of about 215 g / eq., biomass ratio of 28.4 mass%, non-volatile content of 55%), 2 parts of an imidazole-based curing accelerator ("1B2PZ" manufactured by Shikoku Chemical Industry Co., Ltd., 1-benzyl-2-phenylimidazole, MEK solution with solid content of 10 mass%), 180 parts of spherical silica ("SO-C2" manufactured by Admatechs Co., Ltd., average particle size 0.5 μm, biomass ratio 0 mass%) surface-treated with a silane coupling agent ("KBM-573" manufactured by Shin-Etsu Chemical Co., Ltd.), and 5 parts of a phenoxy resin ("YX7553BH30" manufactured by Mitsubishi Chemical Co., Ltd., biomass ratio 0 mass%, 1:1 solution of MEK and cyclohexanone with non-volatile content of 30 mass%), and uniformly dispersed with a high-speed rotating mixer to produce a resin varnish.

[0362] A resin varnish was uniformly applied to the release surface of a support similar to that in Example 1 so that the resin composition layer had a thickness of 40 μm, and then dried at 80°C to 120°C (average 100°C) for 5 minutes to produce a resin sheet.

[0363] <Example 11> 15 parts of bisphenol A type epoxy resin (Mitsui Chemicals, epoxy equivalent about 170g / eq., biomass ratio 100% by mass), 10 parts of naphthylene ether type epoxy resin (DIC "HP-6000", epoxy equivalent about 250g / eq., biomass ratio 0% by mass), 15 parts of furan resin (Daiei Sangyo Co., Ltd. "BioPrepolymer (registered trademark) 1552L", biomass ratio 100% by mass), 20 parts of tetrahydrofuran (THF) and 40 parts of methyl ethyl ketone (MEK) were added as dilution solvents, and the mixture was heated and dissolved with stirring. This was cooled to room temperature to prepare an epoxy resin dissolved composition.

[0364] To this epoxy resin solution composition, 10 parts of a naphthol-type hardener ("SN-485" manufactured by Nippon Steel Chemical & Material Co., Ltd., hydroxyl equivalent of about 205 g / eq., biomass ratio 0 mass%), 1 part of a phosphorus-based hardening accelerator ("TBP-DA" manufactured by Hokko Chemical Industry Co., Ltd., MEK solution with biomass ratio 0 mass% and solid content 20 mass%), 2 parts of a polymerization initiator ("Perhexyl D" manufactured by NOF Corporation, MEK solution with biomass ratio 0 mass% and solid content 10 mass%), and silane coupling agent were added. A resin varnish was produced by mixing 90 parts of spherical silica (Admatechs' SO-C2, average particle size 0.5 μm, biomass ratio 0 mass%) that had been surface-treated with a binder (Shin-Etsu Chemical's KBM-573) and 5 parts of biphenylaralkylnovolac-type maleimide (Nippon Kayaku's MIR-3000-70MT, biomass ratio 0 mass%, MEK / toluene mixed solution with non-volatile component ratio of 70%) and dispersing the mixture uniformly using a high-speed rotating mixer.

[0365] A resin varnish was uniformly applied to the release surface of a support similar to that in Example 1 so that the resin composition layer had a thickness of 40 μm, and then dried at 80°C to 120°C (average 100°C) for 5 minutes to produce a resin sheet.

[0366] <Example 12> In Example 11, 1) 15 parts of the furan resin ("BioPrepolymer (registered trademark) 1552L" manufactured by Daiei Sangyo Co., Ltd., biomass ratio 100% by mass) was changed to 5 parts of PMMVF obtained in Synthesis Example 5, 2) The amount of methyl ethyl ketone (MEK) used as a dilution solvent was changed from 40 parts to 30 parts. A resin varnish and a resin sheet were produced in the same manner as in Example 11 except for the above.

[0367] <Example 13> In Example 11, 15 parts of the furan resin ("BioPrepolymer (registered trademark) 1552L" manufactured by Daiei Sangyo Co., Ltd., biomass ratio 100 mass%) was changed to 15 parts of the polycarbosilane obtained in Synthesis Example 6. A resin varnish and a resin sheet were produced in the same manner as in Example 11.

[0368] <Example 14> In Example 13, 90 parts of spherical silica ("SO-C2" manufactured by Admatechs, average particle size 0.5 μm, biomass ratio 0 mass%) surface-treated with a silane coupling agent ("KBM-573" manufactured by Shin-Etsu Chemical Co., Ltd.) was replaced with 90 parts of biomass silica ("Ethical Silica" manufactured by MIT, average particle size 3.7 μm, biomass ratio 100 mass%) surface-treated with a silane coupling agent ("KBM-573" manufactured by Shin-Etsu Chemical Co., Ltd.). A resin varnish and a resin sheet were produced in the same manner as in Example 13.

[0369] <Comparative Example 1> In Example 1, 1) Without using 10 parts of tetrahydrofuran (THF) as a dilution solvent 2) The amount of methyl ethyl ketone (MEK) used as a dilution solvent was changed from 50 parts to 60 parts. A resin varnish and a resin sheet were produced in the same manner as in Example 1 except for the above.

[0370] <Comparative Example 2> In Comparative Example 1, 1) Without using 40 parts of the furan skeleton-containing polyester resin (1) obtained in Synthesis Example 1 (a toluene solution having an active group equivalent of about 215 g / eq., a biomass ratio of 28.4% by mass, and a non-volatile component ratio of 55%), 2) 34 parts of an active ester compound (DIC Corporation's "HPC-8000-65T", active group equivalent of approximately 223 g / eq., biomass ratio of 0 mass%, non-volatile content of 65% in toluene solution) was added to the resin varnish, 3) Five parts of a phenolic curing agent containing a triazine skeleton (DIC Corporation's "LA-3018-50P", active group equivalent weight approximately 151 g / eq., biomass ratio 0 mass%, non-volatile component ratio 50% in 2-methoxypropanol solution) were added to the resin varnish. A resin varnish and a resin sheet were produced in the same manner as in Comparative Example 1 except for the above.

[0371] <Comparative Example 3> In Comparative Example 2, 1) The amount of methyl ethyl ketone (MEK) used as a dilution solvent was changed from 60 parts to 50 parts. 2) 10 parts of tetrahydrofuran (THF) was added as a dilution solvent to the epoxy resin dissolved composition. A resin varnish and a resin sheet were produced in the same manner as in Comparative Example 2 except for the above.

[0372] <Comparative Example 4> In Example 11, 1) The amount of methyl ethyl ketone (MEK) used as a dilution solvent was changed from 40 parts to 60 parts. 2) 20 parts of tetrahydrofuran (THF) was not used as a dilution solvent. A resin varnish and a resin sheet were produced in the same manner as in Example 11 except for the above.

[0373] <Dielectric tangent measurement test> (1) Preparation of cured material for evaluation: A PET film ("501010" manufactured by Lintec Corporation, thickness 50 μm, 240 mm square) having a release-treated surface treated with a release agent and an untreated surface not treated with a release agent was prepared. A glass cloth-based epoxy resin double-sided copper-clad laminate ("R5715ES" manufactured by Panasonic Corporation, thickness 0.7 mm, 255 mm square) was placed on the untreated surface of this PET film, and the four sides were fixed with polyimide adhesive tape (width 10 mm).

[0374] The resin varnishes prepared in the Examples and Comparative Examples were applied to the release agent-treated surface of the fixed PET film using a die coater and dried at 80° C. to 120° C. (average 100° C.) to form a resin composition layer having a thickness of 40 μm. The drying time was 5 minutes in Examples 1 and 3 to 14 and Comparative Examples 1 to 4, and 7 minutes in Example 2.

[0375] The resin composition layer was then heat-cured by heating in an oven at 190°C for 90 minutes. After heat curing, the polyimide adhesive tape was peeled off, the glass cloth-based epoxy resin double-sided copper-clad laminate was peeled off, and the PET film ("501010" manufactured by Lintec Corporation) was also peeled off to obtain a sheet-like cured product. The obtained cured product may be referred to as "cured product for evaluation".

[0376] (2) Measurement of dielectric tangent: The cured product for evaluation was cut into a length of 80 mm and a width of 2 mm to obtain an evaluation sample. The dielectric tangent of this evaluation sample was measured at a measurement frequency of 5.8 GHz and a measurement temperature of 23°C by a cavity resonance perturbation method using a measurement device ("HP8362B" manufactured by Agilent Technologies). Measurement was performed on two test pieces, and the average value was calculated.

[0377] <Measurement test of average coefficient of linear thermal expansion (CTE) and glass transition temperature Tg> The cured product for evaluation was cut into a length of about 15 mm and a width of about 5 mm to obtain a test piece. A thermomechanical analysis was performed by the tensile load method using a thermomechanical analyzer (Rigaku Corporation's "Thermo Plus TMA8310"). Specifically, after mounting the test piece on the device, measurements were performed twice in succession under the measurement conditions of a load of 1 g and a heating rate of 5°C / min. In the second measurement, the glass transition temperature Tg and the average coefficient of linear thermal expansion (CTE) from 25°C to 150°C were calculated.

[0378] <Evaluation test for unevenness after lamination> (1) Preparation of inner layer board: Both sides of a glass cloth-based epoxy resin double-sided copper-clad laminate (copper foil thickness 18 μm, substrate thickness 0.4 mm, Panasonic "R1515A") with an inner layer circuit made of copper foil on the surface were etched 1 μm with a microetching agent (Mec "CZ8101"). The copper foil surface was roughened by etching, and an inner layer substrate was obtained.

[0379] (2) Lamination of resin sheet: Using a batch-type vacuum pressure laminator (Nikko Materials Co., Ltd., 2-stage build-up laminator "CVP700"), the resin sheets obtained in the examples and comparative examples were laminated on both sides of the inner layer substrate so that the resin composition layer was in contact with the inner layer substrate. Lamination was performed by reducing the pressure for 30 seconds to adjust the air pressure to 13 hPa or less, and then pressing at 120°C and a pressure of 0.74 MPa for 30 seconds. Next, heat pressing was performed at 100°C and a pressure of 0.5 MPa for 60 seconds.

[0380] (3) Evaluation of unevenness after lamination: After lamination, the vicinity of the edge of the resin composition layer along the periphery of the inner layer substrate was observed with an optical microscope at a magnification of 50 times. If dents were observed near the edge of the resin composition layer, the unevenness was evaluated as "present". If no dents were observed, the unevenness was evaluated as "absent". The dents observed here were numerous streaky dents.

[0381] <Measurement test of solvent and THF content in resin composition layer> The amounts of the solvent and THF contained in the resin composition layer after drying were calculated by analysis using a GC-MS method.

[0382] <Result> The results of the above-mentioned Examples and Comparative Examples are shown in the following table. In the table, the meanings of the abbreviations are as follows. "Component A / total components (mass %)" in the "Resin varnish" column: the amount of furan-type curable resin (A) relative to 100 mass % of the total amount of the resin varnish. "Component C / Non-volatile component (mass%)" in the "Resin varnish" column: The amount of inorganic filler (C) relative to 100 mass% of the non-volatile component in the resin varnish. "Total solvent / total components (mass%)" in the "Resin varnish" column: The amount of solvent relative to 100% by mass of the total amount of resin varnish. "THF / total components (mass %)" in the "Resin varnish" column: the amount of (B) tetrahydrofuran relative to 100 mass % of the total amount of the resin varnish. "THF / total components (mass %)" in the "Resin composition layer" column: the amount of (B) tetrahydrofuran relative to 100 mass % of the total amount of the resin composition layer. "Total solvent / total components (mass %)" in the "Resin composition layer" column: the amount of solvent relative to 100 mass % of the total amount of the resin composition layer. "THF / total solvent (mass %)" in the "Resin composition layer" column: the amount of (B) tetrahydrofuran relative to 100 mass % of the solvent in the resin composition layer. "Component A / total components (mass %)" in the "Resin composition layer" column: the amount of furan-type curable resin (A) relative to 100 mass % of the total amount of the resin composition layer. "Biomass ratio (%) of non-volatile components" in the "Resin composition layer" column: Biomass ratio of non-volatile components in the resin composition layer. "Biomass ratio (%) of resin component" in the "Resin composition layer" column: the biomass ratio of the resin component in the resin composition layer. "Tg": glass transition temperature of the cured layer. "CTE": Average coefficient of linear thermal expansion of the cured layer.

[0383] [Table 1]

[0384] <Consideration> Comparative Examples 1 to 4 are all experimental examples relating to a resin composition layer containing (C) an inorganic filler. Of these, Comparative Example 2 does not use either (A) a furan type curable resin or (B) tetrahydrofuran. Comparative Example 3 does not use (A) a furan type curable resin, but uses (B) tetrahydrofuran. In these Comparative Examples 2 and 3, no unevenness occurs. Furthermore, in Comparative Examples 1 and 4, (A) a furan type curable resin is used, but (B) tetrahydrofuran is not used. In these Comparative Examples 1 and 4, unevenness occurs. Therefore, it can be understood from these results that the problem of unevenness occurrence is a specific problem occurring in a resin composition layer containing (A) a furan type curable resin and (C) an inorganic filler.

[0385] In contrast, in Examples 1 to 14, unevenness was successfully suppressed by combining (A) a furan-type curable resin, (B) tetrahydrofuran, and (C) an inorganic filler. Therefore, from the results of Examples 1 to 14, it can be understood that unevenness can be suppressed according to the configuration of the present invention, even when (A) a furan-type curable resin is adopted to increase the biomass ratio.

Claims

1. A resin sheet having a resin composition layer, the resin composition layer contains (A) a curable resin containing a furan skeleton, (B) tetrahydrofuran, and (C) an inorganic filler; (A) the amount of the curable resin containing a furan skeleton is 2% by mass or more with respect to 100% by mass of the total amount of the resin composition layer; (B) the amount of tetrahydrofuran is 0.1% by mass or more with respect to 100% by mass of the total amount of the resin composition layer; (C) A resin sheet, in which the amount of the inorganic filler is 50% by mass or more relative to 100% by mass of the non-volatile components of the resin composition layer.

2. The resin sheet according to claim 1, wherein a biomass ratio of non-volatile components in the resin composition layer, represented by the following formula (M2), is 0.1 mass% or more. Biomass ratio (mass%) = (mass of biological components in non-volatile components / mass of non-volatile components) × 100 (M2)

3. The resin sheet according to claim 1 , wherein the cured layer obtained by curing the resin composition layer has an average linear thermal expansion coefficient of 50 ppm / ° C. or less.

4. The resin sheet according to claim 1 , wherein a cured layer obtained by curing the resin composition layer has a dielectric loss tangent of less than 0.

015.

5. The resin sheet according to claim 1 , wherein the cured layer obtained by curing the resin composition layer has a glass transition temperature of higher than 150° C.

6. A method for producing a circuit board using the resin sheet according to any one of claims 1 to 5, comprising: The manufacturing method comprises: laminating the resin sheet and the inner layer substrate so that the resin composition layer and the inner layer substrate are bonded to each other; A step of curing the resin composition layer; A method for manufacturing a circuit board, comprising:

7. A resin composition comprising (A) a curable resin containing a furan skeleton, (B) tetrahydrofuran, and (C) an inorganic filler, (A) the amount of the curable resin containing a furan skeleton is 2% by mass or more relative to 100% by mass of the total amount of the resin composition; (B) the amount of tetrahydrofuran is 1% by mass or more based on 100% by mass of the total amount of the resin composition; (C) A resin composition, in which the amount of the inorganic filler is 50 mass% or more relative to 100 mass% of the non-volatile components in the resin composition.

8. A method for producing a resin sheet using the resin composition according to claim 7, comprising: The manufacturing method comprises: A step of applying a resin composition onto a support; A step of drying the applied resin composition to form a resin composition layer; Including; A method for producing a resin sheet, wherein the amount of (B) tetrahydrofuran in the resin composition layer is 0.1 mass% or more relative to 100 mass% of the total amount of the resin composition layer.

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