Thermosetting resin composition

Abstract

To provide a thermosetting resin composition capable of obtaining a cured product having suppressed formation of unevenness.SOLUTION: There is provided a thermosetting resin composition which comprises (A) a silane compound having intramolecular cyclization reactivity and (B) a radical reactive resin.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a thermosetting resin composition, a method for producing the same, a resin sheet, a cured product, a circuit board, and a semiconductor device. [Background technology]

[0002] Circuit boards such as printed wiring boards are widely used in various electronic devices. A known method for manufacturing circuit boards is a build-up method in which insulating layers and conductor layers are alternately stacked on an inner layer substrate. The insulating layer is formed, for example, from a cured product of a thermosetting resin composition. Specifically, a thermosetting resin composition layer containing a thermosetting resin composition is formed, and the thermosetting resin composition layer is thermally cured to form an insulating layer containing a cured product of the thermosetting resin composition. Furthermore, the technology described in Patent Document 1 is publicly known. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2022 / 158176 Summary of the Invention [Problem to be solved by the invention]

[0004] In order to suppress transmission loss during operation in a high-frequency environment, the insulating layer is required to have a low dielectric dissipation factor. To achieve such a low dielectric dissipation factor, the present inventors attempted to prepare a thermosetting resin composition using a radical-reactive resin. Radical-reactive resins typically do not generate polar groups when forming bonds through a radical reaction. Therefore, when a cured product is obtained by thermally curing a thermosetting resin composition, the polarity of the cured product can be reduced. Therefore, it was expected that the insulating layer could be formed using a cured product with low polarity, thereby reducing the dielectric dissipation factor of the insulating layer.

[0005] However, the inventors of the present invention have found that when a thermosetting resin composition containing a radical-reactive resin is thermally cured to obtain a cured product, unevenness may occur in the cured product. Such unevenness may reduce the performance of the insulating layer. Furthermore, even if the unevenness does not reduce the performance of the insulating layer, in actual commercial transactions, circuit boards having insulating layers with such unevenness are likely to be valued at a lower value.

[0006] The present invention has been made in view of the above-mentioned problems, and aims to provide a thermosetting resin composition and a method for producing the same that can produce a cured product in which the formation of unevenness is suppressed; a resin sheet containing the thermosetting resin composition; a cured product of the thermosetting resin composition; and a circuit board and a semiconductor device that contain the cured product. [Means for solving the problem]

[0007] The present inventors have conducted extensive research to solve the above-mentioned problems, and as a result, have found that a thermosetting resin composition containing (A) a silane compound having intramolecular cyclization reactivity and (B) a radical-reactive resin can solve the above-mentioned problems, thereby completing the present invention. That is, the present invention includes the following.

[0008] <1> A thermosetting resin composition comprising (A) a silane compound having intramolecular cyclization reactivity and (B) a radical-reactive resin. <2> The amount of the (A) component is 0.1% by mass or more and 2.0% by mass or less, based on 100% by mass of the nonvolatile components of the thermosetting resin composition. <1> The thermosetting resin composition according to claim 1. <3> The component (B) contains one or more selected from the group consisting of a maleimide resin, a (meth)acrylic resin, a styryl resin, and an allyl resin. <1> or <2> The thermosetting resin composition according to claim 1. <4> The component (B) contains a maleimide resin. <1> ~ <3> 10. The thermosetting resin composition according to claim 1, wherein the thermosetting resin composition is a thermosetting resin composition having a viscosity of 1000 MPa or more. <5> (C) containing an inorganic filler; <1> ~ <4> 10. The thermosetting resin composition according to claim 1, wherein the thermosetting resin composition is a thermosetting resin composition having a viscosity of 1000 MPa or more. <6> The component (C) contains (C-1) an inorganic filler that has been surface-treated with the component (A). <5> The thermosetting resin composition according to claim 1. <7> the amount of the surface treatment of the component (C-1) with the component (A) is 0.1% by mass or more and 3.0% by mass or less; <6> The thermosetting resin composition according to claim 1. <8> The amount of component (C) is 50% by mass or more relative to 100% by mass of the nonvolatile components of the thermosetting resin composition. <5> ~ <7> 10. The thermosetting resin composition according to claim 1, wherein the thermosetting resin composition is a thermosetting resin composition having a viscosity of 1000 MPa or more. <9> (D) containing a thermosetting resin; <1> ~ <8> 10. The thermosetting resin composition according to claim 1, wherein the thermosetting resin composition is a thermosetting resin composition having a viscosity of 1000 MPa or more. <10> have a minimum melt viscosity of 4000 poise or less, <1> ~ <9> 10. The thermosetting resin composition according to claim 1, wherein the thermosetting resin composition is a thermosetting resin composition having a viscosity of 1000 MPa or more. <11> For forming insulating layers on circuit boards. <1> ~ <10> 10. The thermosetting resin composition according to claim 1, wherein the thermosetting resin composition is a thermosetting resin composition having a viscosity of 1000 MPa or more. <12> <1> ~ <11> A method for producing the thermosetting resin composition according to any one of the above items: A method for producing a thermosetting resin composition, comprising the step of mixing (A) a silane compound having intramolecular cyclization reactivity and (B) a radical-reactive resin. <13> <1> ~ <11> A method for producing the thermosetting resin composition according to any one of the above items: (A) a silane compound having intramolecular cyclization reactivity and (C') an inorganic filler before surface treatment are mixed to obtain (C-1) an inorganic filler surface-treated with component (A); a step of mixing the component (C-1) with the radical reactive resin (B); A method for producing a thermosetting resin composition, comprising: <14> A support and a thermosetting resin composition layer provided on the support, The thermosetting resin composition layer is <1> ~ <11> A resin sheet comprising the thermosetting resin composition according to any one of claims 1 to 11. <15> <1> ~ <11> 10. A cured product of the thermosetting resin composition according to claim 1. <16> <1> ~ <11> A circuit board comprising a cured product of the thermosetting resin composition according to any one of claims 1 to 4. <17> <16> A semiconductor device comprising the circuit board according to claim 1. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a thermosetting resin composition that can produce a cured product in which the formation of unevenness is suppressed, and a method for producing the same; a resin sheet containing the thermosetting resin composition; a cured product of the thermosetting resin composition; and a circuit board and a semiconductor device that include the cured product. DETAILED DESCRIPTION OF THE INVENTION

[0010] 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.

[0011] As used herein, the term "optionally substituted" in reference to a compound or group means both a case where the hydrogen atoms of the compound or group are not substituted with substituents, and a case where some or all of the hydrogen atoms of the compound or group are substituted with substituents.

[0012] <Summary of Thermosetting Resin Composition> A thermosetting resin composition according to one embodiment of the present invention includes (A) a silane compound having intramolecular cyclization reactivity and (B) a radical-reactive resin. In the following description, the "(A) silane compound having intramolecular cyclization reactivity" may be referred to as the "(A) internally reactive silane compound."

[0013] The thermosetting resin composition according to this embodiment can be thermally cured to form a cured product by reacting the (A) internally reactive silane compound and the (B) radically reactive resin to form bonds under heat. The reactions can include reactions between the (A) internally reactive silane compounds, reactions between the (B) radically reactive resins, and reactions between the (A) internally reactive silane compound and the (B) radically reactive resin. This cured product can be used, for example, to form an insulating layer such as an interlayer insulating layer. Furthermore, the thermosetting resin composition according to this embodiment can suppress the formation of unevenness in the cured product. Furthermore, the thermosetting resin composition according to this embodiment can typically have a low minimum melt viscosity. Furthermore, the cured product of the thermosetting resin composition according to this embodiment can have a low dielectric loss tangent, high strength at break, high elongation at break, and high metal foil adhesion.

[0014] The present inventors speculate that the mechanism by which the thermosetting resin composition according to this embodiment can exhibit the above-described excellent effects is as follows, although the present invention is not limited to the mechanism described below.

[0015] In the past, when a thermosetting resin composition was heated, some of the components would flow due to the heat. When such flow occurred, the composition would become uneven, and "unevenness" would be formed in the cured product of the thermosetting resin composition. To give a specific example, when a thermosetting resin composition was heated, if components with high fluidity moved and components with low fluidity remained, the composition of the thermosetting resin composition would become uneven, and unevenness would be formed in the cured product obtained after thermal curing.

[0016] In contrast, the (A) internally reactive silane compound is capable of undergoing an intramolecular cyclization reaction. Because this intramolecular cyclization reaction occurs within the same molecule, it generally has a faster reaction rate than an intermolecular reaction. Therefore, the (A) internally reactive silane compound can rapidly react with heat to generate active species such as radicals. In the thermosetting resin composition according to this embodiment containing the (A) internally reactive silane compound, the active species generated by the (A) internally reactive silane compound act as the starting point, allowing the reaction to proceed quickly throughout the thermosetting resin composition. Therefore, the reaction can occur before flow occurs, allowing curing to proceed, thereby suppressing flow and thus preventing the formation of unevenness due to flow. Here, the (A) internally reactive silane compound may not only react intramolecularly with the (A) internally reactive silane compound, but also with other molecules.

[0017] Furthermore, since the (A) internally reactive silane compound is usually an organic silane compound, it can enhance the affinity between inorganic components such as (C) an inorganic filler, which will be described later, and organic components such as (B) a radically reactive resin, etc. Therefore, the compatibility between the inorganic component and the organic component can be improved, and the minimum melt viscosity of the thermosetting resin composition can be reduced.

[0018] Furthermore, since (B) the radical-reactive resin typically forms bonds through a radical reaction, the reaction does not generate polar groups such as hydroxyl groups. Similarly, (A) the internally reactive silane compound typically does not generate polar groups through the reaction. Therefore, the cured product obtained by curing the thermosetting resin composition can have low polarity. Therefore, the cured product typically has a low dielectric loss tangent.

[0019] Furthermore, since the thermosetting resin composition can usually be cured before flow occurs as described above, the thermosetting resin composition according to this embodiment can suppress compositional imbalance due to flow. Specifically, if flow occurs, hydrophobic components may gather together or hydrophilic components may gather together, resulting in compositional imbalance. If compositional imbalance occurs in this way, a phase boundary may be formed in the cured product, and this phase boundary may become the starting point for fracture due to stress, potentially reducing the mechanical strength of the cured product. In contrast, suppressing compositional imbalance due to flow can increase the compositional uniformity of the thermosetting resin composition, thereby suppressing the formation of a phase boundary that may become the starting point for fracture in the cured product. Therefore, the resistance to stress can be increased, improving the mechanical strength of the cured product, and typically increasing the strength at break and elongation at break.

[0020] Furthermore, since the cured product can have high mechanical strength, peeling (interlayer delamination) due to destruction of the cured product can usually be suppressed. Furthermore, since the internally reactive silane compound (A) usually has high affinity for both inorganic components and organic components, adhesion at the interface between the cured product and inorganic materials such as metal foil can be increased. Therefore, the cured product of the thermosetting resin composition according to this embodiment can have high adhesion to metal foil.

[0021] The thermosetting resin composition according to this embodiment may further contain optional components in addition to the internally reactive silane compound (A) and the radically reactive resin (B), such as an inorganic filler (C), a thermosetting resin (D), a polymer resin (E), a thermal polymerization initiator (F), and a curing accelerator (G).

[0022] <(A) Internally reactive silane compound> The thermosetting resin composition according to this embodiment includes an internally reactive silane compound (A) as component (A). The internally reactive silane compound (A) typically contains a structure capable of undergoing an intramolecular cyclization reaction. In the following description, the "structure capable of undergoing an intramolecular cyclization reaction" may be referred to as an "internal reactive structure." The internally reactive structure can react within the structure to form a bond, resulting in internal cyclization. Typically, the reaction is a radical reaction using a radical as the active species. Therefore, the internally reactive structure typically contains a structure capable of generating a radical.

[0023] Examples of structures capable of generating radicals include non-aromatic carbon-carbon unsaturated bonds such as non-aromatic carbon-carbon double bonds and non-aromatic carbon-carbon triple bonds. Therefore, the internal reactive structure may contain a non-aromatic carbon-carbon unsaturated bond. For example, the internal reactive structure may contain multiple non-aromatic carbon-carbon unsaturated bonds within the internal reactive structure, and these non-aromatic carbon-carbon unsaturated bonds may be capable of reacting with each other.

[0024] An example of the internal reactive structure is a structure represented by the following formula (A1).

[0025] [ka]

[0026] (In formula (A1), R 3 represents a hydrogen atom or a methyl group; A 1 represents a single bond or a divalent hydrocarbon group having 1 to 20 carbon atoms which may have a substituent; A 2 , A 3 , A 4 each independently represents a methylene group which may have a substituent, or an oxygen atom, provided that A 2 , A 3 and A 4 At least one of the atoms is an oxygen atom, and the oxygen atoms are not adjacent to each other. * represents a bonding site.)

[0027] In formula (A1), R 3 represents a hydrogen atom or a methyl group.

[0028] In formula (A1), A 1 represents a single bond; or a divalent hydrocarbon group having 1 to 20 carbon atoms which may have a substituent. A 1 The divalent hydrocarbon group may be linear, branched, or cyclic. Examples of the divalent hydrocarbon group include an alkylene group having usually 1 to 20 carbon atoms, preferably 1 to 10 carbon atoms, and more preferably 1 to 6 carbon atoms; a cycloalkylene group having 3 to 20 carbon atoms; an alkenylene group having 2 to 10 carbon atoms; an arylene group having 6 to 10 carbon atoms; and an aralkylene group having 7 to 10 carbon atoms. Specific examples of divalent hydrocarbon groups include alkylene groups such as methylene, ethylene, propylene, trimethylene, tetramethylene, pentamethylene, hexamethylene, heptamethylene, and octamethylene; cycloalkylene groups such as cyclohexylene; alkenylene groups such as vinylene and propenylene; arylene groups such as phenylene, tolylene, xylylene, and naphthylene; and aralkylene groups such as benzylene, phenylethylene, and phenylpropylene.

[0029] A 1 Examples of the substituent that the divalent hydrocarbon group may have include a halogen atom, an alkoxy group, a cycloalkyloxy group, an alkylthio group, a cycloalkylthio group, an aryloxy group, an arylthio group, a monovalent aliphatic heterocyclic group, an acyloxy group, an amino group, a silyl group, a carboxy group, a sulfo group, a cyano group, a nitro group, a mercapto group, and an oxo group.

[0030] A 1 is preferably a divalent hydrocarbon group having no substituent (unsubstituted divalent hydrocarbon group); more preferably a divalent alkylene group; still more preferably an alkylene group having 1 to 10 carbon atoms; and particularly preferably a linear alkylene group having 1 to 10 carbon atoms.

[0031] In formula (A1), A 2 , A3 and A 4 each independently represents a methylene group which may have a substituent or an oxygen atom. 2 , A 3 and A 4 At least one of the atoms is an oxygen atom, but the oxygen atoms are never adjacent to each other.

[0032] A 2 , A 3 and A 4 Examples of the substituent that the methylene group may have include a halogen atom, an alkyl group, an alkenyl group, a cycloalkyl group, an alkoxy group, a cycloalkyloxy group, an alkylthio group, a cycloalkylthio group, an aryl group, an aryloxy group, an arylthio group, an arylalkyl group, an arylalkoxy group, a monovalent aliphatic heterocyclic group, an alkylidene group, an acyl group, an acyloxy group, an amino group, a silyl group, a carboxy group, a sulfo group, a cyano group, a nitro group, a mercapto group, and an oxo group. Examples of the substituted methylene group include a methylmethylene group and a dimethylmethylene group.

[0033] A 2 , A 3 and A 4 When A is a methylene group, the methylene group is preferably a methylene group having no substituent (unsubstituted methylene group). 2 is preferably a methylene group which may have a substituent, and particularly preferably an unsubstituted methylene group. 3 is preferably an oxygen atom. 4 is preferably a methylene group which may have a substituent, and particularly preferably an unsubstituted methylene group.

[0034] The number of internal reactive structures contained in one molecule of the (A) internally reactive silane compound may be 1 or 2 or more. When the (A) internally reactive silane compound contains two or more internal reactive structures in one molecule, the internal reactive structures may be the same or different. The number of internal reactive structures contained in one molecule of the (A) internally reactive silane compound is preferably 1.

[0035] The (A) internally reactive silane compound contains a silicon atom, and an internally reactive structure is bonded to this silicon atom. The internally reactive structure may be bonded directly to the silicon atom or may be bonded via a suitable linking group. For example, in the (A) internally reactive silane compound containing the internally reactive structure represented by formula (A1), A 1 can function as a linking group, and A in formula (A1) 1 The moiety other than the group can undergo a cyclization reaction.

[0036] The silicon atom of the (A) internally reactive silane compound may have any organic group bonded to it other than the internally reactive structure. Examples of the optional organic group include hydrocarbon groups such as alkyl groups having 1 to 10 carbon atoms and aryl groups having 6 to 10 carbon atoms; alkyloxy groups having 1 to 10 carbon atoms; alkenyloxy groups having 2 to 10 carbon atoms; aryloxy groups having 6 to 10 carbon atoms; and acyloxy groups having 1 to 20 carbon atoms. The number of optional organic groups contained in one molecule of the (A) internally reactive silane compound may be 1 or 2 or more. Preferably, the number of optional organic groups contained in one molecule of the (A) internally reactive silane compound is 1 to 3, and more preferably 3.

[0037] A preferred internally reactive silane compound (A) is a compound represented by the following formula (A2).

[0038] [ka]

[0039] (In formula (A2), R 1 each independently represents an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, or an acyl group having 1 to 20 carbon atoms; R 2 each independently represents an alkyl group having 1 to 10 carbon atoms or an aryl group having 6 to 10 carbon atoms; R 3 represents a hydrogen atom or a methyl group; A 1represents a single bond or a divalent hydrocarbon group having 1 to 20 carbon atoms which may have a substituent; A 2 , A 3 , A 4 each independently represents a methylene group which may have a substituent, or an oxygen atom, provided that A 2 , A 3 and A 4 At least one of the groups is an oxygen atom, and the oxygen atoms are not adjacent to each other; and n represents an integer of 1 to 3.

[0040] In formula (A2), R 1 R each independently represents an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, or an acyl group having 1 to 20 carbon atoms. 1 Specific examples of the alkyl group include linear, branched, or cyclic alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, neopentyl, n-hexyl, n-octyl, and cyclohexyl; alkenyl groups such as vinyl, allyl, and propenyl; aryl groups such as phenyl, tolyl, xylyl, and naphthyl; and acyl groups such as formyl, acetyl, and propionyl. Among these, alkyl groups having 1 to 8 carbon atoms are preferred, alkyl groups having 1 to 6 carbon atoms are more preferred, and methyl and ethyl groups are even more preferred.

[0041] In formula (A2), R 2 R each independently represents an alkyl group having 1 to 10 carbon atoms or an aryl group having 6 to 10 carbon atoms. 2Specific examples of include linear, branched, or cyclic alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, neopentyl, n-hexyl, n-octyl, and cyclohexyl; and aryl groups such as phenyl, tolyl, xylyl, and naphthyl. Among these, alkyl groups and phenyl groups having 1 to 8 carbon atoms are preferred; alkyl groups and phenyl groups having 1 to 6 carbon atoms are more preferred; and methyl, ethyl, and phenyl groups are even more preferred.

[0042] In formula (A2), n represents an integer of 1 to 3.

[0043] In formula (A2), R 3 , A 1 , A 2 , A 3 and A 4 is the same as in formula (A1).

[0044] The (A) internally reactive silane compound is preferably a compound represented by the following formula (A3).

[0045] [ka]

[0046] (In formula (A3), R 1 , R 2 , R 3 , A 2 , A 3 , A 4 and n are the same as in formulae (A1) and (A2); and m represents an integer of 1 to 10.

[0047] In formula (A3), m represents an integer of 1 to 10, preferably an integer of 2 to 10, and more preferably an integer of 2 to 6.

[0048] As the (A) internally reactive silane compound, a compound represented by the following formula (A4) is more preferred.

[0049] [ka]

[0050] (In formula (A4), R 1 , R 2 , m, and n are the same as those in formulas (A1) to (A3).

[0051] Specific examples of the (A) internally reactive silane compound include compounds represented by the following formulas (a-1) to (a-4): In the following formulas, Me represents a methyl group, and Et represents an ethyl group.

[0052] [ka]

[0053] Here, a specific example of the intramolecular cyclization reaction in an (A) internally reactive silane compound will be described using a compound represented by formula (a-1) as an example. When an internally reactive structure is attacked by a radical R, as in step (1) in the following reaction scheme, an intramolecular cyclization reaction can proceed as in step (2), resulting in internal cyclization. This reaction is repeated as shown in step (3), resulting in a polymerization reaction to form the repeating unit represented by formula (a'-1). The intramolecular cyclization reaction shown in steps (1) and (2) generally proceeds faster than intermolecular reactions, so the reaction proceeds rapidly in a thermosetting resin composition, thereby achieving effects such as suppressing unevenness. The following reaction scheme shows an example in which a reaction between (A) internally reactive silane compounds proceeds in step (3). However, in a thermosetting resin composition, the intramolecular cyclization reaction can also trigger a reaction between the (A) internally reactive silane compound and the (B) radically reactive resin, and a reaction between the (B) radically reactive resins.

[0054] [ka]

[0055] The (A) internally reactive silane compound may be used alone or in combination of two or more.

[0056] The kinematic viscosity of the internally reactive silane compound (A) is not particularly limited, but is preferably 0.1 mm 2 / s or more, preferably 0.5 mm 2 / s or more, more preferably 1 mm 2 / s or more, preferably 1000 mm 2 / s or less, preferably 100 mm 2 / s or less, more preferably 10 mm 2 The kinematic viscosity is not more than 1 / s. The kinematic viscosity can be measured at 25°C in accordance with JIS Z 8803.

[0057] There are no limitations on the method for producing the (A) internally reactive silane compound. For example, the compound represented by formula (A2) can be produced by the method described in International Publication No. 2022 / 158176. The (A) internally reactive silane compound may also be purchased from the market. For example, the compound represented by formula (a-1) is available as "X-12-1333A" manufactured by Shin-Etsu Chemical Co., Ltd.

[0058] There are no limitations on the state of the (A) internally reactive silane compound in the thermosetting resin composition. Therefore, the (A) internally reactive silane compound may be in a free state in the resin component of the thermosetting resin composition. The (A) internally reactive silane compound may also be in a state adsorbed to the surface of the (C) inorganic filler. Unless otherwise specified, the "resin component" of a thermosetting resin composition refers to the non-volatile components of the thermosetting resin composition excluding the (A) internally reactive silane compound and the (C) inorganic filler. Furthermore, unless otherwise specified, the "non-volatile components" of a thermosetting resin composition refers to the components other than the solvent contained in the thermosetting resin composition.

[0059] In particular, from the viewpoint of significantly achieving the effects of the present invention, it is preferable that the (A) internally reactive silane compound is adsorbed on the surface of the (C) inorganic filler. Usually, by subjecting the (C) inorganic filler before treatment with the (A) internally reactive silane compound to surface treatment with the (A) internally reactive silane compound, the (A) internally reactive silane compound is adsorbed on the surface of the (C) inorganic filler. Therefore, by mixing the surface-treated (C) inorganic filler with other components, a thermosetting resin composition containing the (A) internally reactive silane compound adsorbed on the surface of the (C) inorganic filler can be obtained.

[0060] The amount of the (A) internally reactive silane compound is preferably at least 0.1 mass%, more preferably at least 0.2 mass%, and particularly preferably at least 0.3 mass%, relative to 100 mass% of the nonvolatile components of the thermosetting resin composition, and is preferably at most 5.0 mass%, more preferably at most 3.0 mass%, and particularly preferably at most 2.0 mass%. When the amount of the (A) internally reactive silane compound is within this range, the formation of unevenness in the cured product of the thermosetting resin composition can be effectively suppressed, and moreover, the minimum melt viscosity of the thermosetting resin composition, as well as the dielectric loss tangent, strength at break, elongation at break, and metal foil adhesion of the cured product can usually be effectively improved.

[0061] The amount of the (A) internally reactive silane compound is preferably 0.2% by mass or more, more preferably 0.4% by mass or more, even more preferably 0.6% by mass or more, and is preferably 15% by mass or less, more preferably 12% by mass or less, and particularly preferably 10% by mass or less, relative to 100% by mass of the resin components of the thermosetting resin composition. When the amount of the (A) internally reactive silane compound is within this range, the formation of unevenness in the cured product of the thermosetting resin composition can be effectively suppressed, and moreover, the minimum melt viscosity of the thermosetting resin composition, as well as the dielectric loss tangent, strength at break, elongation at break, and metal foil adhesion of the cured product can usually be effectively improved.

[0062] The amount of the (A) internally reactive silane compound is preferably at least 0.1 mass%, more preferably at least 0.2 mass%, and even more preferably at least 0.5 mass%, relative to 100 mass% of the (B) radically reactive resin. When the amount of the (A) internally reactive silane compound is within this range, the formation of unevenness in the cured product of the thermosetting resin composition can be effectively suppressed, and moreover, the minimum melt viscosity of the thermosetting resin composition, as well as the dielectric loss tangent, strength at break, elongation at break, and metal foil adhesion of the cured product can usually be effectively improved.

[0063] When the thermosetting resin composition contains a (C) inorganic filler, the amount of the (A) internal reactive silane compound is preferably at least 0.01% by mass, more preferably at least 0.05% by mass, and even more preferably at least 0.1% by mass, relative to 100% by mass of the combined total of the (A) internal reactive silane compound and the (C) inorganic filler. The amount of the (A) internal reactive silane compound within this range effectively prevents unevenness in the cured product of the thermosetting resin composition. Furthermore, the minimum melt viscosity of the thermosetting resin composition, as well as the dielectric loss tangent, strength at break, elongation at break, and metal foil adhesion of the cured product, are typically effectively improved. When the (C) inorganic filler is surface-treated with an optional surface treatment agent other than the (A) internal reactive silane compound, the amount of the (C) inorganic filler includes the amount of the optional surface treatment agent.

[0064] <(B) Radical reactive resin> The thermosetting resin composition according to this embodiment includes a (B) radical-reactive resin as component (B). Unless otherwise specified, the (B) radical-reactive resin does not include those corresponding to the above-mentioned component (A). Because the (B) radical-reactive resin reacts with heat to form bonds, the thermosetting resin composition can be thermally cured to form a cured product.

[0065] (B) The radical-reactive resin generally contains a radical-reactive unsaturated group. This radical-reactive unsaturated group is a group containing an unsaturated bond exhibiting radical reactivity. Examples of this radical-reactive unsaturated group include a group containing a non-aromatic carbon-carbon unsaturated bond.

[0066] Examples of radically reactive unsaturated groups include unsaturated hydrocarbon groups such as vinyl, allyl, 1-propenyl, 3-cyclohexenyl, 3-cyclopentenyl, 2-vinylphenyl, 3-vinylphenyl, and 4-vinylphenyl; and α,β-unsaturated carbonyl groups such as acryloyl, methacryloyl, and maleimide (2,5-dihydro-2,5-dioxo-1H-pyrrol-1-yl) groups. The number of radically reactive unsaturated groups contained in the (B) radically reactive resin is usually 1 or more, preferably 2 or more. When the (B) radically reactive resin contains two or more radically reactive unsaturated groups, the two or more radically reactive unsaturated groups may be the same or different.

[0067] Preferred examples of the (B) radical-reactive resin include maleimide resins, (meth)acrylic resins, styryl resins, and allyl resins. Therefore, the (B) radical-reactive resin preferably contains one or more selected from the group consisting of maleimide resins, (meth)acrylic resins, styryl resins, and allyl resins. Among these, from the viewpoint of significantly achieving the effects of the present invention, it is more preferred that the (B) radical-reactive resin contains a maleimide resin.

[0068] The maleimide resin refers to a resin having one or more, preferably two or more, maleimide groups (2,5-dihydro-2,5-dioxo-1H-pyrrol-1-yl groups) per molecule. The maleimide 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. Among these, the maleimide resin preferably includes an aromatic maleimide resin.

[0069] Examples of aliphatic maleimide resins include maleimide resins having a carbon skeleton derived from dimer acid. A carbon skeleton derived from dimer acid refers to a carbon skeleton obtained by removing the two terminal carboxyl groups (-COOH) of a dimer acid, or a carbon skeleton obtained by replacing the two terminal carboxyl groups (-COOH) with methylene groups (-CH2-). Dimer acid is a known compound obtained by dimerizing unsaturated fatty acids (preferably those having 11 to 22 carbon atoms, more preferably those having 14 to 20 carbon atoms, and particularly preferably those having 18 carbon atoms), and its industrial production process is largely standardized in the industry. Dimer acids are easily available, particularly those containing a 36-carbon dimer acid as the main component, which is obtained by dimerizing an 18-carbon unsaturated fatty acid such as oleic acid or linoleic acid, which are inexpensive and readily available. Furthermore, dimer acids may contain arbitrary amounts of monomer acids, trimer acids, other polymerized fatty acids, etc., depending on the production method, degree of purification, etc. Furthermore, double bonds remain after the polymerization reaction of unsaturated fatty acids, but in this specification, hydrogenated products in which the degree of unsaturation is reduced by further hydrogenation reaction are also included in the dimer acid.

[0070] Examples of maleimide resins having a carbon skeleton derived from a dimer acid include maleimide resins represented by formula (B1).

[0071] [ka]

[0072] (In formula (B1), n1+1 Xs each independently represent a divalent organic group consisting of five or more skeletal atoms selected from carbon atoms, nitrogen atoms (not forming imides), oxygen atoms, and sulfur atoms, and non-skeletal atoms selected from hydrogen atoms and halogen atoms, and at least one of the n1+1 Xs represents a divalent hydrocarbon group derived from a dimer acid; n1 Ys each independently represent a tetravalent organic group consisting of five or more skeletal atoms selected from carbon atoms, nitrogen atoms (not forming an imide), oxygen atoms, and sulfur atoms, and non-skeletal atoms selected from hydrogen atoms and halogen atoms; n1 represents an integer of 0 or 1 or more.

[0073] In formula (B1), n1+1 Xs each independently represent a divalent organic group. The divalent organic group is composed of five or more skeletal atoms and non-skeletal atoms. The five or more skeletal atoms are selected from carbon atoms, nitrogen atoms (not forming imides), oxygen atoms, and sulfur atoms. The number of skeletal atoms is usually five or more, preferably 5 to 200, more preferably 5 to 100, and even more preferably 5 to 50. The non-skeletal atoms are selected from hydrogen atoms and halogen atoms. Furthermore, at least one of the n1+1 Xs represents a divalent hydrocarbon group derived from a dimer acid.

[0074] The divalent hydrocarbon group derived from a dimer acid means a divalent hydrocarbon group obtained by removing the two terminal carboxy groups (-COOH) of a dimer acid, or a divalent hydrocarbon group obtained by replacing the two terminal carboxy groups (-COOH) with methylene groups (-CH-).

[0075] The n1+1 Xs may have a divalent organic group other than a divalent hydrocarbon group derived from a dimer acid, but when the n1+1 Xs are taken as 100 mol%, it is preferable that 30 mol% or more of them are divalent hydrocarbon groups derived from a dimer acid, more preferably 60 mol% or more are divalent hydrocarbon groups derived from a dimer acid, even more preferably 90 mol% or more are divalent hydrocarbon groups derived from a dimer acid, and it is particularly preferable that (all) the n1+1 Xs are divalent hydrocarbon groups derived from a dimer acid.

[0076] The divalent organic group other than the divalent hydrocarbon group derived from a dimer acid among the n1+1 Xs may be a divalent organic group without an aromatic ring, or may be a divalent organic group with an aromatic ring.

[0077] In formula (B1), n1 Ys each independently represent a tetravalent organic group. The tetravalent organic group consists of five or more skeletal atoms and non-skeletal atoms. The five or more skeletal atoms are selected from carbon atoms, nitrogen atoms (not forming imides), oxygen atoms, and sulfur atoms. The number of skeletal atoms is usually five or more, preferably 5 to 200, more preferably 5 to 100, and even more preferably 5 to 50. The non-skeletal atoms are selected from hydrogen atoms and halogen atoms. The tetravalent organic group represented by Y may be a tetravalent organic group without an aromatic ring, or may be a tetravalent organic group with an aromatic ring.

[0078] The tetravalent organic group represented by Y is preferably represented by any one of the formulae (Y1) to (Y5).

[0079] [ka]

[0080] [In formulas (Y1) to (Y5), ring Y 11 , ring Y 21 , ring Y 22 , ring Y 31 , ring Y 32 , ring Y 33 , ring Y 41 , ring Y 42 , ring Y 43 , ring Y 44 , ring Y 51 , ring Y 52 , ring Y 53 , ring Y 54 and ring Y 55 each independently represents an aromatic ring which may have a substituent or a non-aromatic ring which may have a substituent; Y 2a , Y 3a , Y 3b , Y 4a , Y 4b , Y 4c , Y 5a , Y 5b , Y 5c and Y 5d are each independently a single bond, -C(R y)2-, -O-, -CO-, -S-, -SO-, -SO2-, -CONH-, or -NHCO-; R y each independently represents a hydrogen atom or an alkyl group which may be substituted with a halogen atom, or two R y are bonded together to form a non-aromatic ring which may have a substituent; * indicates a bonding site. The two bonding sites on the same ring represented by * are bonding sites to two adjacent carbon atoms on the ring.

[0081] In the formulae (Y1) to (Y5), the ring Y 11 , ring Y 21 , ring Y 22 , ring Y 31 , ring Y 32 , ring Y 33 , ring Y 41 , ring Y 42 , ring Y 43 , ring Y 44 , ring Y 51 , ring Y 52 , ring Y 53 , ring Y 54 and ring Y 55 each independently represents an aromatic ring which may have a substituent, or a non-aromatic ring which may have a substituent; preferably represents an aromatic ring which may have a substituent; more preferably represents a benzene ring which may have a substituent; and even more preferably represents a benzene ring which may be substituted with an alkyl group.

[0082] The aromatic ring refers to a ring that conforms to Hückel's rule, in which the number of electrons contained in the π-electron system on the ring is 4p+2 (p is a natural number). The aromatic ring may be an aromatic carbocycle containing only carbon atoms as ring-constituting atoms, or an aromatic heterocycle containing heteroatoms such as oxygen atoms, nitrogen atoms, and sulfur atoms as ring-constituting atoms in addition to carbon atoms. The aromatic ring is preferably an aromatic carbocycle. Furthermore, the aromatic ring such as an aromatic carbocycle is preferably a 5- to 14-membered aromatic ring, more preferably a 6- to 14-membered aromatic ring, and even more preferably a 6- to 10-membered aromatic ring. Suitable specific examples of the aromatic carbocycle include a benzene ring, a naphthalene ring, an anthracene ring, and a phenanthrene ring, with a benzene ring or a naphthalene ring being more preferred, and a benzene ring being particularly preferred.

[0083] The non-aromatic ring means a ring other than an aromatic ring that has aromaticity throughout the ring. The non-aromatic ring may be a non-aromatic carbocyclic ring having only carbon atoms as ring-constituting atoms, or a non-aromatic heterocyclic ring having heteroatoms such as oxygen atoms, nitrogen atoms, and sulfur atoms as ring-constituting atoms in addition to carbon atoms. The non-aromatic ring is preferably a non-aromatic carbocyclic ring. The non-aromatic ring may be a saturated ring or an unsaturated ring. The non-aromatic ring is preferably a 3- to 21-membered non-aromatic ring, more preferably a 4- to 17-membered non-aromatic ring, and even more preferably a 5- to 14-membered non-aromatic ring. Specific preferred examples of the non-aromatic ring (non-aromatic carbocycle) include monocyclic non-aromatic saturated carbocycles such as a cyclobutane ring, a cyclopentane ring, a cyclohexane ring, a cycloheptane ring, and a cyclooctane ring; monocyclic non-aromatic unsaturated carbocycles such as a cyclobutene ring, a cyclopentene ring, a cyclohexene ring, a cycloheptene ring, a cyclooctene ring, a cyclopentadiene ring, and a cyclohexadiene ring; bicyclo[2.2.1]heptane ring (norbornane ring), bicyclo[4.4.0]decane ring (decalin ring), bicyclo[5.3.0]decane ring, bicyclo[4.3.0]nonane ring (hydrindane ring), bicyclo[3.2.1]octane ring, bicyclo[5.4.0]undecane ring, bicyclo[3.3.0]octane ring, bicyclo[3.3.1]nonane ring, tricyclo[5.2.1.0 2,6 ] Decane ring (tetrahydrodicyclopentadiene ring), tricyclo[3.3.1.1 3,7] Decane ring (adamantane ring), tricyclo[6.2.1.0 2,7 and bicyclo[2.2.1]hept-2-ene (norbornene ring), bicyclo[2.2.2]oct-2-ene ring, bicyclo[4.4.0]dec-2-ene ring, and other non-aromatic unsaturated bicyclic or higher ring systems. The non-aromatic ring may be a non-aromatic ring partially fused with an aromatic ring. Examples of non-aromatic rings partially fused with an aromatic ring include an indane ring, an indene ring, a tetralin ring, a 1,2-dihydronaphthalene ring, a 1,4-dihydronaphthalene ring, a fluorene ring, a 9,10-dihydroanthracene ring, and a 9,10-dihydrophenanthrene ring.

[0084] Ring Y 11 , ring Y 21 , ring Y 22 , ring Y 31 , ring Y 32 , ring Y 33 , ring Y 41 , ring Y 42 , ring Y 43 , ring Y 44 , ring Y 51 , ring Y 52 , ring Y 53 , ring Y 54 and ring Y 55 Examples of the "substituent" in the "optionally substituted aromatic ring" and the "optionally substituted non-aromatic ring" include a halogen atom, -NO2, -CN, -COH, -OH, -SH, -NH2, -COOH, -R b , -COR b , -OR b , -SR b , -SOR b , -SO2R b , -NHR b , -NR b 2. -COOR b , -OCOR b , -CONH2, -CONHR b , -CONR b 2, -NHCOR b (However, R b each independently represents a monovalent hydrocarbon group.

[0085] R b The number of carbon atoms in the monovalent hydrocarbon group represented by is preferably 1 to 50, more preferably 1 to 20. The monovalent hydrocarbon group may be a monovalent saturated hydrocarbon group or a monovalent unsaturated hydrocarbon group. Furthermore, the monovalent hydrocarbon group may or may not have an aromatic structure. Examples of monovalent hydrocarbon groups include alkyl groups, alkenyl groups, aryl groups, aralkyl groups, and alkylaryl groups.

[0086] The alkyl group may be linear, branched, or cyclic. The number of carbon atoms in the alkyl group is preferably 1 to 14, more preferably 1 to 10, even more preferably 1 to 6, and particularly preferably 1 to 3. Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a pentyl group, an isopentyl group, a sec-pentyl group, a neopentyl group, a tert-pentyl group, a hexyl group, an isohexyl group, a heptyl group, an isoheptyl group, an octyl group, an isooctyl group, a tert-octyl group, a cyclopentyl group, a cyclohexyl group, and a cyclohexylmethyl group.

[0087] The alkenyl group may be linear, branched, or cyclic. The number of carbon atoms in the alkenyl group is preferably 2 to 14, more preferably 2 to 10, even more preferably 2 to 6, and particularly preferably 2 to 3. Examples of the alkenyl group include a vinyl group, a propenyl group (allyl group, 1-propenyl group, isopropenyl group), a butenyl group (1-butenyl group, crotyl group, methallyl group, isocrotyl group, etc.), a pentenyl group (1-pentenyl group, etc.), a hexenyl group (1-hexenyl group, etc.), a heptenyl group (1-heptenyl group, etc.), an octenyl group (1-octenyl group, etc.), a cyclopentenyl group (2-cyclopentenyl group, etc.), and a cyclohexenyl group (3-cyclohexenyl group).

[0088] The number of carbon atoms in the aryl group is preferably 6 to 14, more preferably 6 to 10. Examples of the aryl group include a phenyl group, a 1-naphthyl group, and a 2-naphthyl group.

[0089] The aralkyl group may be an alkyl group substituted with one or more (preferably one) aryl groups. The number of carbon atoms in the aralkyl group is preferably 7 to 15, more preferably 7 to 11. Examples of the aralkyl group include a benzyl group, a phenethyl group, a hydrocinnamyl group, an α-methylbenzyl group, an α-cumyl group, a 1-naphthylmethyl group, and a 2-naphthylmethyl group.

[0090] The alkylaryl group may be an aryl group substituted with one or more (preferably one) alkyl groups. The number of carbon atoms in the alkylaryl group is preferably 7 to 15, more preferably 7 to 11. Examples of the alkylaryl group include a 4-methylphenyl group, a 3-methylphenyl group, a 2-methylphenyl group, a 4-ethylphenyl group, a 3-ethylphenyl group, a 2-ethylphenyl group, a 4-isopropylphenyl group, a 3-isopropylphenyl group, and a 2-isopropylphenyl group.

[0091] In formulas (Y1) to (Y5), Y 2a , Y 3a , Y 3b , Y 4a , Y 4b , Y 4c , Y 5a , Y 5b , Y 5c and Y 5d are each independently a single bond, -C(R y )2-, -O-, -CO-, -S-, -SO-, -SO2-, -CONH-, or -NHCO-; preferably, a single bond, -C(R y )2- or -O-.

[0092] R y each independently represents a hydrogen atom or an alkyl group which may be substituted with a halogen atom, or two Ry are bonded together to form a non-aromatic ring which may have a substituent. b The alkyl group in R y are each independently preferably a hydrogen atom or an alkyl group which may be substituted with a halogen atom; more preferably a hydrogen atom or a methyl group which may be substituted with a halogen atom; even more preferably a hydrogen atom, a methyl group, or a trifluoromethyl group; and particularly preferably a hydrogen atom or a methyl group.

[0093] R y Examples of the "substituent" in the "optionally substituted non-aromatic ring" formed by the formula (I) include a halogen atom, -NO2, -CN, -COH, -OH, -SH, -NH2, -COOH, -R b , -COR b , -OR b , -SR b , -SOR b , -SO2R b , -NHR b , -NR b 2. -COOR b , -OCOR b , -CONH2, -CONHR b , -CONR b 2, -NHCOR b (R b is as described above).

[0094] In formula (B1), n1 represents 0 or an integer of 1 or more; preferably 0 or an integer of 1 to 10; more preferably 0.

[0095] The aromatic maleimide resin may be, for example, a maleimide resin represented by formula (B2).

[0096] [ka]

[0097] (In formula (B2), R 10each independently represents a hydrogen atom or an alkyl group which may be substituted with a halogen atom; each ring D independently represents an aromatic carbocyclic ring which may be substituted; and n2 represents an integer of 1 or greater. The n2 units may be the same or different for each unit.

[0098] In formula (B2), R 10 are each independently a hydrogen atom or an alkyl group which may be substituted with a halogen atom. b The alkyl group in R 10 are each independently preferably a hydrogen atom or an alkyl group; more preferably a hydrogen atom or a methyl group; and even more preferably a hydrogen atom.

[0099] In formula (B2), each ring D independently represents an aromatic carbocyclic ring which may have a substituent. 11 , ring Y 21 , ring Y 22 , ring Y 31 , ring Y 32 , ring Y 33 , ring Y 41 , ring Y 42 , ring Y 43 , ring Y 44 , ring Y 51 , ring Y 52 , ring Y 53 , ring Y 54 and ring Y 55 The "substituent" in ring D may be the same as the aromatic carbocyclic ring described in the section on the aromatic ring in 11 , ring Y 21 , ring Y 22 , ring Y 31 , ring Y 32 , ring Y 33 , ring Y 41 , ring Y 42 , ring Y 43 , ring Y 44 , ring Y 51 , ring Y 52 , ring Y 53 , ring Y 54 and ring Y 55The substituents may be the same as those in the "aromatic ring which may have a substituent" in the above. Ring D preferably represents a benzene ring which may have a substituent; more preferably represents a benzene ring which may be substituted with a group selected from an alkyl group and an aryl group; and particularly preferably represents an (unsubstituted) benzene ring.

[0100] In formula (B2), n2 represents an integer of 1 or more, and preferably represents an integer of 1 to 10.

[0101] Another example of the aromatic maleimide resin is a maleimide resin represented by formula (B3).

[0102] [ka]

[0103] (In formula (B3), R 20 each independently represents a hydrogen atom or an alkyl group which may be substituted with a halogen atom; ring E, ring F, and ring G each independently represents an aromatic carbocyclic ring which may have a substituent; and n3 represents an integer of 1 or greater. The n3 units may be the same or different for each unit.

[0104] In formula (B3), R 20 are each independently a hydrogen atom or an alkyl group which may be substituted with a halogen atom. b The alkyl group in R 20 are each independently preferably a hydrogen atom or an alkyl group; more preferably a hydrogen atom or a methyl group; and even more preferably a hydrogen atom.

[0105] In formula (B3), ring E, ring F, and ring G each independently represent an aromatic carbocyclic ring which may have a substituent. 11 , ring Y 21 , ring Y 22 , ring Y 31 , ring Y32 , ring Y 33 , ring Y 41 , ring Y 42 , ring Y 43 , ring Y 44 , ring Y 51 , ring Y 52 , ring Y 53 , ring Y 54 and ring Y 55 The "substituents" in rings E, F and G may be the same as those in ring Y. 11 , ring Y 21 , ring Y 22 , ring Y 31 , ring Y 32 , ring Y 33 , ring Y 41 , ring Y 42 , ring Y 43 , ring Y 44 , ring Y 51 , ring Y 52 , ring Y 53 , ring Y 54 and ring Y 55 The substituents in the "optionally substituted aromatic ring" in the formula (1) may be the same as those in the formula (1). Ring E, ring F, and ring G each independently preferably represent a benzene ring which may have a substituent; more preferably represent a benzene ring which may be substituted with a group selected from an alkyl group and an aryl group; and particularly preferably represent an (unsubstituted) benzene ring.

[0106] In formula (B3), n3 represents an integer of 1 or more, and preferably represents an integer of 1 to 10.

[0107] Yet another example of the aromatic maleimide resin is a maleimide resin represented by formula (B4).

[0108] [ka]

[0109] (In formula (B4), R 30each independently represents an alkyl group; ring H and ring I each independently represent an aromatic carbocyclic ring which may have a substituent; and n4 represents an integer of 1 or greater. The n4 units may be the same or different from one another.

[0110] In formula (B4), R 30 are each independently an alkyl group. The alkyl group is represented by R b The alkyl group in R 30 are each independently preferably a methyl group.

[0111] In formula (B4), each ring H independently represents an aromatic ring which may have a substituent. 11 , ring Y 21 , ring Y 22 , ring Y 31 , ring Y 32 , ring Y 33 , ring Y 41 , ring Y 42 , ring Y 43 , ring Y 44 , ring Y 51 , ring Y 52 , ring Y 53 , ring Y 54 and ring Y 55 The "substituent" in ring H may be the same as the aromatic carbocyclic ring described in the section on the aromatic ring in 11 , ring Y 21 , ring Y 22 , ring Y 31 , ring Y 32 , ring Y 33 , ring Y 41 , ring Y 42 , ring Y 43 , ring Y 44 , ring Y 51 , ring Y 52 , ring Y 53 , ring Y 54 and ring Y 55The substituents in the "optionally substituted aromatic ring" in the formula (1) may be the same as those in the "optionally substituted aromatic ring" in the formula (1). Each ring H independently preferably represents a benzene ring which may have a substituent; more preferably represents a benzene ring which may be substituted with an alkyl group; even more preferably represents a benzene ring substituted with an alkyl group; and particularly preferably represents a benzene ring substituted with a methyl group.

[0112] In formula (B4), each ring I independently represents an aromatic ring which may have a substituent. 11 , ring Y 21 , ring Y 22 , ring Y 31 , ring Y 32 , ring Y 33 , ring Y 41 , ring Y 42 , ring Y 43 , ring Y 44 , ring Y 51 , ring Y 52 , ring Y 53 , ring Y 54 and ring Y 55 The "substituent" in ring I may be the same as the aromatic carbocyclic ring described in the section on the aromatic ring in ring Y. 11 , ring Y 21 , ring Y 22 , ring Y 31 , ring Y 32 , ring Y 33 , ring Y 41 , ring Y 42 , ring Y 43 , ring Y 44 , ring Y 51 , ring Y 52 , ring Y 53 , ring Y 54 and ring Y 55 The substituents in the "optionally substituted aromatic ring" in the formula (I) may be the same as those in the "optionally substituted aromatic ring" in the formula (I). Each ring I independently preferably represents a benzene ring which may have a substituent; more preferably represents a benzene ring which may be substituted with an alkyl group; and even more preferably represents an (unsubstituted) benzene ring.

[0113] In formula (B4), n4 represents an integer of 1 or more, and preferably an integer of 1 to 20.

[0114] Commercially available maleimide resins include, for example, dimer diamine structure-containing maleimide resins such as "SLK-2600" and "SLK-6895-T90" (resins represented by the following formula (b-1)) manufactured by Shin-Etsu Chemical Co., Ltd.; dimer diamine structure-containing maleimide resins such as "BMI-1500," "BMI-1700," "BMI-3000J," "BMI-689," and "BMI-2500" manufactured by Designer Molecules Inc.; Examples of suitable maleimide resins include aromatic maleimide resins such as "BMI-6100" manufactured by Nippon Kayaku Co., Ltd.; biphenylaralkyl maleimide resins such as "MIR-5000-60T," "MIR-3000-70MT," and "MIR-3000-70T" (resin of formula (b-2) below) manufactured by Nippon Kayaku Co., Ltd.; "BMI-70" and "BMI-80" manufactured by K.I. Chemical Industry Co., Ltd.; "BMI-2300" (resin of formula (b-3) below) and "BMI-TMH" manufactured by Daiwa Chemical Industry Co., Ltd. Furthermore, the maleimide resin (indan ring skeleton-containing maleimide compound) disclosed in the Japan Institute of Invention and Innovation's Disclosure Technical Bulletin No. 2020-500211 may also be used.

[0115] [ka]

[0116] (In the above formula, m1 represents 2 or 3, and m2 represents 1 or 2.)

[0117] The amount of maleimide resin is preferably 1% by mass or more, more preferably 5% by mass or more, even more preferably 10% by mass or more, and preferably 50% by mass or less, more preferably 40% by mass or less, and even more preferably 30% by mass or less, relative to 100% by mass of the non-volatile components of the thermosetting resin composition. When the amount of maleimide resin is within the above range, the formation of unevenness in the cured product of the thermosetting resin composition can be effectively suppressed, and moreover, the minimum melt viscosity of the thermosetting resin composition, as well as the dielectric loss tangent, strength at break, elongation at break, and metal foil adhesion of the cured product can usually be effectively improved.

[0118] The amount of maleimide resin is preferably 10% by mass or more, more preferably 20% by mass or more, even more preferably 30% by mass or more, and preferably 90% by mass or less, more preferably 80% by mass or less, and even more preferably 70% by mass or less, based on 100% by mass of the resin components of the thermosetting resin composition. When the amount of maleimide resin is within the above range, the formation of unevenness in the cured product of the thermosetting resin composition can be effectively suppressed, and moreover, the minimum melt viscosity of the thermosetting resin composition, as well as the dielectric loss tangent, strength at break, elongation at break, and metal foil adhesion of the cured product can usually be effectively improved.

[0119] The amount of the aromatic maleimide resin is preferably 1% by mass or more, more preferably 5% by mass or more, and even more preferably 10% by mass or more, relative to 100% by mass of the non-volatile components of the thermosetting resin composition, and is preferably 50% by mass or less, more preferably 40% by mass or less, and even more preferably 30% by mass or less. When the amount of the aromatic maleimide resin is within the above range, the formation of unevenness in the cured product of the thermosetting resin composition can be effectively suppressed, and further, usually, the minimum melt viscosity of the thermosetting resin composition, as well as the dielectric loss tangent, strength at break, elongation at break, and metal foil adhesion of the cured product can be effectively improved.

[0120] The amount of the aromatic maleimide resin is preferably 10% by mass or more, more preferably 20% by mass or more, and even more preferably 30% by mass or more, relative to 100% by mass of the resin components of the thermosetting resin composition, and is preferably 90% by mass or less, more preferably 80% by mass or less, and even more preferably 70% by mass or less. When the amount of the aromatic maleimide resin is within the above range, the formation of unevenness in the cured product of the thermosetting resin composition can be effectively suppressed, and moreover, the minimum melt viscosity of the thermosetting resin composition, as well as the dielectric loss tangent, strength at break, elongation at break, and metal foil adhesion of the cured product can usually be effectively improved.

[0121] The (meth)acrylic resin refers to a resin having one or more, preferably two or more, (meth)acryloyl groups in one molecule. The term "(meth)acryloyl group" can include an acryloyl group, a methacryloyl group, and a combination thereof. Examples of the (meth)acrylic resin include cyclohexane-1,4-dimethanol di(meth)acrylate, cyclohexane-1,3-dimethanol di(meth)acrylate, tricyclodecane dimethanol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,8-octanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, and the like. Low molecular weight (molecular weight less than 1000) aliphatic (meth)acrylic acid ester resins such as 1,10-decanediol di(meth)acrylate, 1,10-decanediol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, trimethylolethane tri(meth)acrylate, glycerin tri(meth)acrylate, and pentaerythritol tetra(meth)acrylate; dioxane glycol di(meth)acrylate, 3,6-dioxa-1,8-octanediol di(meth)acrylate, Examples of the acrylate include low molecular weight (molecular weight less than 1000) ether-containing (meth)acrylic acid ester resins such as acrylate, 3,6,9-trioxaundecane-1,11-diol di(meth)acrylate, polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, 9,9-bis[4-(2-acryloyloxyethoxy)phenyl]fluorene, ethoxylated bisphenol A di(meth)acrylate, and propoxylated bisphenol A di(meth)acrylate; low molecular weight (molecular weight less than 1000) isocyanurate-containing (meth)acrylic acid ester resins such as tris(3-hydroxypropyl)isocyanurate tri(meth)acrylate, tris(2-hydroxyethyl)isocyanurate tri(meth)acrylate, and ethoxylated isocyanuric acid tri(meth)acrylate; and high molecular weight (molecular weight 1000 or more) acrylic acid ester resins such as (meth)acrylic-modified polyphenylene ether resins. The term "(meth)acrylate" may include acrylates, methacrylates, and combinations thereof.Examples of commercially available (meth)acrylic resins include "A-DOG" (dioxane glycol diacrylate) manufactured by Shin-Nakamura Chemical Co., Ltd., "DCP-A" (tricyclodecane dimethanol diacrylate) and "DCP" (tricyclodecane dimethanol 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.

[0122] The styryl resin refers to a resin having one or more, preferably two or more, styryl groups or vinyl groups directly bonded to aromatic carbon atoms per molecule. Examples of the styryl resin include low-molecular-weight (molecular-weight less than 1000) styryl resins such as divinylbenzene, 2,4-divinyltoluene, 2,6-divinylnaphthalene, 1,4-divinylnaphthalene, 4,4'-divinylbiphenyl, 1,2-bis(4-vinylphenyl)ethane, 2,2-bis(4-vinylphenyl)propane, and bis(4-vinylphenyl)ether; and high-molecular-weight (molecular-weight 1000 or more) styryl resins such as vinylbenzyl-modified polyphenylene ether resins and styrene-divinylbenzene copolymers. Examples of commercially available styryl resins include "ODV-XET(X03)", "ODV-XET(X04)", and "ODV-XET(X05)" (styrene-divinylbenzene copolymers) manufactured by Nippon Steel Chemical & Material Co., Ltd.; and "OPE-2St", "OPE-2St 1200", and "OPE-2St 2200" (vinylbenzyl-modified polyphenylene ether) manufactured by Mitsubishi Gas Chemical Company, Inc.

[0123] The allyl resin refers to a resin having one or more, preferably two or more, allyl groups in one molecule. Examples of allyl resins include aromatic carboxylic acid allyl ester resins such as diallyl diphenate, triallyl trimellitate, diallyl phthalate, diallyl isophthalate, diallyl terephthalate, diallyl 2,6-naphthalenedicarboxylate, and diallyl 2,3-naphthalenecarboxylate; isocyanuric acid allyl ester resins such as 1,3,5-triallyl isocyanurate and 1,3-diallyl-5-glycidyl isocyanurate; epoxy-containing aromatic allyl resins such as 2,2-bis[3-allyl-4-(glycidyloxy)phenyl]propane; benzoxazine-containing aromatic allyl resins such as bis[3-allyl-4-(3,4-dihydro-2H-1,3-benzoxazin-3-yl)phenyl]methane; ether-containing aromatic allyl resins such as 1,3,5-triallyl ether benzene; allyl silane resins such as diallyl diphenyl silane; and resins containing multiple benzene rings and multiple allyl groups. Commercially available allyl resins include, for example, "TAIC" (1,3,5-triallyl isocyanurate) manufactured by Nippon Kasei Chemical Industry Co., Ltd., "DAD" (diallyl diphenate) manufactured by Nisshoku Techno Fine Chemical Co., Ltd., "TRIAM-705" (triallyl trimellitate) manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., "DAND" (2,3-naphthalenecarboxylic acid diallyl) manufactured by Nisshoku Techno Fine Chemical Co., Ltd., and "ALP-d" (bis[3-allyl isocyanurate) manufactured by Shikoku Chemical Industry Co., Ltd. Examples include "RE-810NM" (2,2-bis[3-allyl-4-(glycidyloxy)phenyl]propane) manufactured by Nippon Kayaku Co., Ltd., "DA-MGIC" (1,3-diallyl-5-glycidyl isocyanurate) manufactured by Shikoku Chemicals Corporation, and "NE-V-1100-70T" (a resin containing multiple benzene rings and multiple allyl groups) manufactured by DIC Corporation.

[0124] The (B) radical reactive resin may be used alone or in combination of two or more.

[0125] The radical reactive unsaturated group equivalent of the radical reactive resin is preferably 20 g / eq. to 3000 g / eq., more preferably 50 g / eq. to 2500 g / eq., even more preferably 70 g / eq. to 2000 g / eq., and particularly preferably 90 g / eq. to 1500 g / eq. The radical reactive unsaturated group equivalent represents the mass of the radical reactive resin per equivalent of the radical reactive unsaturated group.

[0126] The weight average molecular weight (Mw) of the radical reactive resin is preferably 40,000 or less, more preferably 10,000 or less, even more preferably 5,000 or less, and particularly preferably 3,000 or less. The lower limit is not particularly limited, but may be, for example, 150 or more. The weight average molecular weight of the radical reactive resin can be measured as a polystyrene-equivalent value by gel permeation chromatography (GPC).

[0127] The amount of (B) radical-reactive resin is preferably 1% by mass or more, more preferably 5% by mass or more, even more preferably 10% 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, relative to 100% by mass of the non-volatile components of the thermosetting resin composition. When the amount of (B) radical-reactive resin is within this range, the formation of unevenness in the cured product of the thermosetting resin composition can be effectively suppressed, and moreover, the minimum melt viscosity of the thermosetting resin composition, as well as the dielectric loss tangent, strength at break, elongation at break, and metal foil adhesion of the cured product can usually be effectively improved.

[0128] The amount of the (B) radical-reactive resin is preferably 30% by mass or more, more preferably 40% by mass or more, and even more preferably 50% by mass or more, relative to 100% by mass of the resin components of the thermosetting resin composition, and is preferably 99% by mass or less, more preferably 95% by mass or less, and even more preferably 90% by mass or less. When the amount of the (B) radical-reactive resin is within the above range, the formation of unevenness in the cured product of the thermosetting resin composition can be effectively suppressed, and moreover, the minimum melt viscosity of the thermosetting resin composition, as well as the dielectric loss tangent, strength at break, elongation at break, and metal foil adhesion of the cured product can usually be effectively improved.

[0129] <(C) Inorganic filler> The thermosetting resin composition according to this embodiment may contain an inorganic filler (C) as an optional component. The inorganic filler (C) as component (C) is contained in the thermosetting resin composition in the form of particles, and is contained in the cured product while maintaining the particulate form.

[0130] (C) Inorganic filler materials can be inorganic compounds. Examples of (C) inorganic filler materials include silica, alumina, glass, cordierite, silicon oxide, barium sulfate, barium carbonate, talc, clay, mica powder, zinc oxide, hydrotalcite, boehmite, aluminum hydroxide, magnesium hydroxide, calcium carbonate, magnesium carbonate, magnesium oxide, boron nitride, aluminum nitride, manganese nitride, aluminum borate, strontium carbonate, strontium titanate, calcium titanate, magnesium titanate, bismuth titanate, titanium oxide, zirconium oxide, barium titanate, barium titanate zirconate, barium zirconate, calcium zirconate, zirconium phosphate, and zirconium tungstate phosphate. Among these, silica and alumina are preferred, and silica is particularly preferred. Examples of silica include amorphous silica, fused silica, crystalline silica, synthetic silica, and hollow silica. Spherical silica is preferred. The (C) inorganic filler may be used alone or in combination of two or more.

[0131] (A) Inorganic fillers can be classified into hollow inorganic fillers that have voids inside and solid inorganic fillers that do not have voids inside. Hollow inorganic fillers that have voids inside usually have a porosity greater than 0% by volume because they have voids. When (A) inorganic fillers contain hollow inorganic fillers, the dielectric constant of the cured product can be reduced.

[0132] The range of the porosity of the hollow inorganic filler is not particularly limited, but is preferably 5% by volume or more, more preferably 10% by volume or more, and even more preferably 20% by volume or more, and is preferably 95% by volume or less, more preferably 90% by volume or less, and even more preferably 85% by volume or less. The porosity P (volume %) of a particle is defined as the volume-based ratio of the total volume of one or more voids present inside the particle to the total volume of the particle based on the outer surface of the particle (total volume of voids / volume of particle). This porosity P is calculated by multiplying the measured value D of the actual density of the particle by the volume of the particle. M (g / cm 3 ), and the theoretical value of the material density of the material that forms the particle, D T (g / cm 3 ) can be calculated using the following formula (M1).

[0133]

number

[0134] The amount of hollow inorganic filler may be 0% by mass or more, and is preferably 1% by mass or more, more preferably 2% by mass or more, even more preferably 3% by mass or more, and is preferably 50% by mass or less, more preferably 30% by mass or less, even more preferably 10% by mass or less, relative to 100% by mass of the total amount of (C) inorganic filler. Unless otherwise specified, the amount of (C) inorganic filler, the amount of solid inorganic filler, and the amount of hollow inorganic filler include the amount of the surface treatment agent described below.

[0135] (C) Examples of commercially available inorganic fillers include "SP60-05" and "SP507-05" manufactured by Nippon Steel Chemical & Material Co., Ltd.; "YC100C," "YA050C," "YA050C-MJE," "YA010C," "SC2500SQ," "SO-C4," "SO-C2," and "SO-C1" manufactured by Admatechs Co., Ltd.; "UFP-30," "DAW-03," and "FB-105FD" manufactured by Denka Co., Ltd.; "Silfil NSS-3N," "Silfil NSS-4N," and "Silfil NSS-5N" manufactured by Tokuyama Corporation; "CellSpheres" and "MGH-005" manufactured by Taiheiyo Cement Corporation; "Spherique" and "BA-1" manufactured by JGC Catalysts and Chemicals Co., Ltd.; and "Hi-Presica FH" manufactured by Ube Exsymo Co., Ltd.

[0136] The (C) inorganic filler is preferably surface-treated with a surface treatment agent. In this case, it is preferable to use an (A) internally reactive silane compound as the surface treatment agent. Therefore, the (C) inorganic filler preferably includes (C-1) an inorganic filler surface-treated with an (A) internally reactive silane compound. Hereinafter, the "(C-1) inorganic filler surface-treated with an (A) internally reactive silane compound" may be referred to as the "(C-1) specially treated inorganic filler." Typically, the (C-1) specially treated inorganic filler may include particles of the above-mentioned inorganic compound and the (A) internally reactive silane compound adsorbed on the surface of the particles.

[0137] The surface treatment amount of the (C-1) specially treated inorganic filler with the (A) internally reactive silane compound is preferably 0.05% by mass or more, more preferably 0.1% by mass or more, even more preferably 0.2% by mass or more, and preferably 3.0% by mass or less, more preferably 2.7% by mass or less, and even more preferably 2.5% by mass or less. The surface treatment amount is expressed as the ratio of the (A) internally reactive silane compound used to surface treat the particles relative to 100% by mass of the inorganic compound particles before surface treatment. Therefore, this surface treatment amount usually represents the ratio of the (A) internally reactive silane compound adsorbed to the particles relative to 100% by mass of the inorganic compound particles contained in the (C-1) specially treated inorganic filler. When the surface treatment amount with the (A) internally reactive silane compound is within the above range, the formation of unevenness in the cured product of the thermosetting resin composition can be effectively suppressed, and further, the minimum melt viscosity of the thermosetting resin composition, as well as the dielectric loss tangent, strength at break, elongation at break, and metal foil adhesion of the cured product can usually be effectively improved.

[0138] The (C-1) specially treated inorganic filler may be surface-treated with an arbitrary surface treatment agent other than the (A) internally reactive silane compound in combination with the (A) internally reactive silane compound. In this case, the (C-1) specially treated inorganic filler may be surface-treated in the order of the (A) internally reactive silane compound and the arbitrary surface treatment agent. Alternatively, the (C-1) specially treated inorganic filler may be surface-treated in the order of the arbitrary surface treatment agent and the (A) internally reactive silane compound. Furthermore, the (C-1) specially treated inorganic filler may be surface-treated simultaneously with the (A) internally reactive silane compound and the arbitrary surface treatment agent.

[0139] Examples of the optional surface treatment agent include a fluorine-containing silane coupling agent, an aminosilane coupling agent, an epoxysilane coupling agent, a mercaptosilane coupling agent, a silane coupling agent, an alkoxysilane, an organosilazane compound, and a titanate coupling agent. Commercially available surface treatment agents include, for example, 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). Any surface treatment agent may be used alone or in any combination of two or more.

[0140] The surface treatment amount of the (C-1) specially treated inorganic filler with the optional surface treatment agent may be 0% by mass or greater, and is preferably 0.1% by mass or greater, more preferably 0.2% by mass or greater, even more preferably 0.3% by mass or greater, and preferably 3.0% by mass or less, more preferably 2.5% by mass or less, and even more preferably 2.0% by mass or less. The surface treatment amount is expressed as the ratio of the optional surface treatment agent used to treat the particles relative to 100% by mass of the particles of the inorganic compound before surface treatment. Therefore, this surface treatment amount usually represents the ratio of the optional surface treatment agent adsorbed to the particles relative to 100% by mass of the particles of the inorganic compound contained in the (C-1) specially treated inorganic filler. When the surface treatment amount with the optional surface treatment agent is within the above range, the formation of unevenness in the cured product of the thermosetting resin composition can be effectively suppressed, and further, usually, the minimum melt viscosity of the thermosetting resin composition, as well as the dielectric loss tangent, strength at break, elongation at break, and metal foil adhesion of the cured product can be effectively improved.

[0141] The amount of the (C-1) specially treated inorganic filler is preferably 30% by mass or more, more preferably 35% by mass or more, and even more preferably 40% by mass or more, relative to 100% by mass of the nonvolatile components of the thermosetting resin composition, and is preferably 90% by mass or less, more preferably 85% by mass or less, and even more preferably 80% by mass or less. When the amount of the (C-1) specially treated inorganic filler is within this range, the formation of unevenness in the cured product of the thermosetting resin composition can be effectively suppressed, and typically, the minimum melt viscosity of the thermosetting resin composition, as well as the dielectric tangent, strength at break, elongation at break, and metal foil adhesion of the cured product can be effectively improved. Unless otherwise specified, the amount of the (C-1) specially treated inorganic filler includes the amount of the (A) internally reactive silane compound and any surface treatment agent adsorbed to the particles of the (C-1) specially treated inorganic filler by surface treatment.

[0142] The amount of the (C-1) specially treated inorganic filler is preferably 50% by mass or more, more preferably 60% by mass or more, and even more preferably 70% by mass or more, based on 100% by mass of the total amount of the (C) inorganic filler. When the amount of the (C-1) specially treated inorganic filler is within this range, the formation of unevenness in the cured product of the thermosetting resin composition can be effectively suppressed, and typically, the minimum melt viscosity of the thermosetting resin composition, as well as the dielectric tangent, strength at break, elongation at break, and metal foil adhesion of the cured product can be effectively improved. Unless otherwise specified, the amount of the (C) inorganic filler includes the amount of the (A) internally reactive silane compound and any surface treatment agent, etc., adsorbed to the particles of the (C) inorganic filler by surface treatment.

[0143] The (C) inorganic filler may include (C-2) an inorganic filler that has not been surface-treated with (A) an internally reactive silane compound. Hereinafter, the "(C-2) inorganic filler that has not been surface-treated with (A) an internally reactive silane compound" may be referred to as the "(C-2) optional inorganic filler." The (C-2) optional inorganic filler may be an inorganic filler that has not been surface-treated with a surface treatment agent, or may be an inorganic filler that has been surface-treated with an optional surface treatment agent other than the (A) internally reactive silane compound.

[0144] The surface treatment amount of the optional inorganic filler (C-2) with the optional surface treatment agent may be 0% by mass or more, and is preferably 0.1% by mass or more, more preferably 0.2% by mass or more, even more preferably 0.3% by mass or more, and is preferably 5.0% by mass or less, more preferably 3.0% by mass or less, and even more preferably 2.0% by mass or less. The surface treatment amount is expressed as the ratio of the optional surface treatment agent used to treat the surface of the particles to 100% by mass of the particles of the inorganic compound before surface treatment. Therefore, this surface treatment amount usually represents the ratio of the optional surface treatment agent adsorbed to the particles to 100% by mass of the particles of the inorganic compound contained in the optional inorganic filler (C-2).

[0145] The amount of the optional inorganic filler (C-2) may be 0% by mass or more, and is preferably 1% by mass or more, more preferably 5% by mass or more, even more preferably 10% by mass or more, and is preferably 90% by mass or less, more preferably 80% by mass or less, even more preferably 75% by mass or less, relative to 100% by mass of the non-volatile components of the thermosetting resin composition. Unless otherwise specified, the amount of the optional inorganic filler (C-2) includes the amount of any surface treatment agent adsorbed to the particles of the optional inorganic filler (C-2) by surface treatment.

[0146] The amount of the optional inorganic filler (C-2) may be 0% by mass or more, preferably 1% by mass or more, more preferably 10% by mass or more, and even more preferably 20% by mass or more, relative to 100% by mass of the total amount of the inorganic filler (C). The upper limit is usually 100% by mass or less, and may be 70% by mass or less, 50% by mass or less, or 30% by mass or less.

[0147] The average particle size of the (C) inorganic filler is preferably 0.01 μm or more, more preferably 0.05 μm or more, even more preferably 0.1 μm or more, and is preferably 10 μm or less, more preferably 5 μm or less, even more preferably 3 μm or less.

[0148] The average particle size of the (C) inorganic filler can be measured by a laser diffraction / scattering method based on Mie scattering theory. Specifically, a volumetric particle size distribution of the (C) inorganic filler is prepared using a laser diffraction / scattering particle size distribution analyzer, and the median diameter is used as the average particle size. A measurement sample can be prepared by weighing 100 mg of inorganic filler and 10 g of methyl ethyl ketone into a vial and dispersing the mixture ultrasonically for 10 minutes. The measurement sample is measured using a laser diffraction particle size distribution analyzer with blue and red light source wavelengths using a flow cell system to measure the volumetric particle size distribution of the (C) inorganic filler, and the median diameter can be calculated from the obtained particle size distribution. Examples of laser diffraction particle size distribution analyzers include the "LA-960" manufactured by Horiba, Ltd.

[0149] (C) The specific surface area of ​​the inorganic filler is preferably 0.1 m 2 / g or more, more preferably 0.5m 2 / g or more, more preferably 1m 2 / g or more, particularly preferably 3m 2 / g or more, preferably 100m 2 / g or less, more preferably 70m 2 / g or less, more preferably 50m 2 / g or less, particularly preferably 40m 2 (C) The specific surface area of ​​the inorganic filler can be measured in accordance with the BET method by adsorbing nitrogen gas onto the surface of a sample using a specific surface area measuring device (Macsorb HM-1210 manufactured by Mountech Co., Ltd.) and calculating the specific surface area using the BET multipoint method.

[0150] The amount of the (C) inorganic filler is preferably at least 50% by mass, more preferably at least 51% by mass, and even more preferably at least 52% by mass, relative to 100% by mass of the nonvolatile components of the thermosetting resin composition, and is preferably at most 90% by mass, more preferably at most 80% by mass, and even more preferably at most 75% by mass. When the amount of the (C) inorganic filler is within this range, the formation of unevenness in the cured product of the thermosetting resin composition can be effectively suppressed, and moreover, the minimum melt viscosity of the thermosetting resin composition, as well as the dielectric loss tangent, strength at break, elongation at break, and metal foil adhesion of the cured product can usually be effectively improved.

[0151] The amount of inorganic compound particles contained in the (C) inorganic filler (usually the amount of the (C) inorganic filler excluding the surface treatment agent) relative to 100% by mass of the nonvolatile components of the thermosetting resin composition may be the same as the aforementioned range of the amount of the (C) inorganic filler relative to 100% by mass of the nonvolatile components of the thermosetting resin composition. When the amount of inorganic compound particles contained in the (C) inorganic filler is within the aforementioned range, the formation of unevenness in the cured product of the thermosetting resin composition can be effectively suppressed, and further, the minimum melt viscosity of the thermosetting resin composition, as well as the dielectric loss tangent, strength at break, elongation at break, and metal foil adhesion of the cured product can usually be effectively improved.

[0152] The total amount of the (A) internal reactive silane compound and the (C) inorganic filler is preferably 30% by mass or more, more preferably 40% by mass or more, even more preferably 50% by mass or more, and preferably 90% by mass or less, more preferably 85% by mass or less, even more preferably 80% by mass or less, based on 100% by mass of the nonvolatile components of the thermosetting resin composition. The total amount of the (A) internal reactive silane compound and the (C) inorganic filler typically represents the sum of the amount of the (C) inorganic filler (including the (A) internal reactive silane compound contained in the (C) inorganic filler as a surface treatment agent) and the amount of the (A) internal reactive silane compound that is not adsorbed to the (C) inorganic filler and remains free in the resin component. When the total amount of the (A) internal reactive silane compound and the (C) inorganic filler is within the above range, the formation of unevenness in the cured product of the thermosetting resin composition can be effectively suppressed, and typically, the minimum melt viscosity of the thermosetting resin composition, as well as the dielectric loss tangent, strength at break, elongation at break, and metal foil adhesion of the cured product can be effectively improved.

[0153] The total amount of the (A) internally reactive silane compound, (B) radically reactive resin, and (C) inorganic filler is preferably 50% by mass or more, more preferably 60% by mass or more, and even more preferably 70% by mass or more, based on 100% by mass of the non-volatile components of the thermosetting resin composition. The upper limit is usually 100% by mass or less, and may be 99% by mass or less or 98% by mass or less. The total amount of the (A) internally reactive silane compound, (B) radically reactive resin, and (C) inorganic filler usually represents the sum of the amount of the (C) inorganic filler (including the (A) internally reactive silane compound contained in the (C) inorganic filler as a surface treatment agent), the amount of the (A) internally reactive silane compound that is free in the resin component and not adsorbed to the (C) inorganic filler, and the amount of the (B) radically reactive resin. When the total amount of the (A) internally reactive silane compound, the (B) radically reactive resin, and the (C) inorganic filler is within the above range, the formation of unevenness in the cured product of the thermosetting resin composition can be effectively suppressed, and further, usually, the minimum melt viscosity of the thermosetting resin composition, as well as the dielectric loss tangent, strength at break, elongation at break, and metal foil adhesion of the cured product can be effectively improved.

[0154] <(D)Thermosetting resin> The thermosetting resin composition according to this embodiment may contain a (D) thermosetting resin as an optional component. Unless otherwise specified, the (D) thermosetting resin as component (D) does not include components (A) to (C) described above. The (D) thermosetting resin can form bonds by inducing a reaction other than a radical reaction when exposed to heat. Therefore, the thermosetting resin composition can be thermally cured to form a cured product not only by the reaction of the (B) radical-reactive resin but also by the reaction of the (D) thermosetting resin.

[0155] The (D) thermosetting resin is a resin that reacts with heat to form bonds and cure the thermosetting resin composition, and represents a component other than components (A) to (C). Examples of this thermosetting resin include epoxy resins, phenolic resins, benzoxazine resins, active ester resins, cyanate ester resins, carbodiimide resins, acid anhydride resins, and amine resins. Of these, epoxy resins, phenolic resins, benzoxazine resins, and active ester resins are preferred. One type of (D) thermosetting resin may be used alone, or two or more types may be used in combination.

[0156] As the epoxy resin, a curable resin having an epoxy group can be used. Examples of epoxy resins include bixylenol-type epoxy resins, bisphenol A-type epoxy resins, bisphenol F-type epoxy resins, bisphenol S-type epoxy resins, bisphenol AF-type epoxy resins, dicyclopentadiene-type epoxy resins, trisphenol-type epoxy resins, naphthol novolac-type epoxy resins, phenol novolac-type epoxy resins, tert-butyl-catechol-type epoxy resins, naphthalene-type epoxy resins, naphthol-type epoxy resins, anthracene-type epoxy resins, glycidylamine-type epoxy resins, glycidyl ester-type epoxy resins, cresol novolac-type epoxy resins, phenol aralkyl-type epoxy resins, biphenyl-type epoxy resins, linear aliphatic epoxy resins, epoxy resins having a butadiene structure, alicyclic epoxy resins, heterocyclic epoxy resins, spiro ring-containing epoxy resins, cyclohexane-type epoxy resins, cyclohexane dimethanol-type epoxy resins, naphthylene ether-type epoxy resins, trimethylol-type epoxy resins, tetraphenylethane-type epoxy resins, isocyanurate-type epoxy resins, and phenolphthalimidine-type epoxy resins. The epoxy resin may be used alone or in combination of two or more.

[0157] From the viewpoint of obtaining a cured product having excellent heat resistance, the epoxy resin preferably contains an epoxy resin containing an aromatic structure. The aromatic structure is a chemical structure generally defined as aromatic, and also includes polycyclic aromatic rings and aromatic heterocycles. Examples of epoxy resins containing an aromatic structure include bisphenol A type epoxy resins, bisphenol F type epoxy resins, bisphenol S type epoxy resins, bisphenol AF type epoxy resins, dicyclopentadiene type epoxy resins, trisphenol type epoxy resins, naphthol novolac type epoxy resins, phenol novolac type epoxy resins, tert-butyl-catechol type epoxy resins, naphthalene type epoxy resins, naphthol type epoxy resins, anthracene type epoxy resins, bisxyleneol type epoxy resins, glycidylamine type epoxy resins having an aromatic structure, glycidyl ester type epoxy resins having an aromatic structure, cresol novolac type epoxy resins, biphenyl type epoxy resins, linear aliphatic epoxy resins having an aromatic structure, epoxy resins having a butadiene structure having an aromatic structure, alicyclic epoxy resins having an aromatic structure, heterocyclic epoxy resins, spiro ring-containing epoxy resins having an aromatic structure, cyclohexanedimethanol type epoxy resins having an aromatic structure, naphthylene ether type epoxy resins, trimethylol type epoxy resins having an aromatic structure, and tetraphenylethane type epoxy resins having an aromatic structure.

[0158] The thermosetting resin preferably contains an epoxy resin having two or more epoxy groups in one molecule, and the proportion of the epoxy resin having two or more epoxy groups in one molecule is preferably 50% by mass or more, more preferably 60% by mass or more, and even more preferably 70% by mass or more, relative to 100% by mass of the non-volatile components of the epoxy resin.

[0159] Epoxy resins include epoxy resins that are liquid at a temperature of 20°C (hereinafter sometimes referred to as "liquid epoxy resins") and epoxy resins that are solid at a temperature of 20°C (hereinafter sometimes referred to as "solid epoxy resins"). The thermosetting resin composition may contain only a liquid epoxy resin as the epoxy resin, only a solid epoxy resin, or a combination of a liquid epoxy resin and a solid epoxy resin.

[0160] The liquid epoxy resin is preferably a liquid epoxy resin having two or more epoxy groups in one molecule, such as bisphenol A epoxy resin, bisphenol F epoxy resin, bisphenol AF epoxy resin, naphthalene epoxy resin, glycidyl ester epoxy resin, glycidyl amine epoxy resin, phenol novolac epoxy resin, alicyclic epoxy resin having an ester skeleton, cyclohexane epoxy resin, cyclohexanedimethanol epoxy resin, or epoxy resin having a butadiene structure.

[0161] Specific examples of liquid epoxy resins include "HP-4032", "HP-4032-D", and "HP-4032-SS" (naphthalene type epoxy resins) manufactured by DIC Corporation; "828US", "828EL", "jER828EL", "825", and "Epikote 828EL" (bisphenol A type epoxy resins) manufactured by Mitsubishi Chemical Corporation; "jER807" and "1750" (bisphenol F type epoxy resins) manufactured by Mitsubishi Chemical Corporation; "jER152" (phenol novolac type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "630", "630LSD", and "604" (glycidylamine type epoxy resins) manufactured by Mitsubishi Chemical Corporation; "ED-523T" (glycirol type epoxy resin) manufactured by ADEKA Corporation; and "EP-3950L" and "EP-3980" manufactured by ADEKA Corporation. Examples of epoxy resins include "EP-4088S" (glycidylamine type epoxy resin) manufactured by ADEKA Corporation, "EP-4088S" (dicyclopentadiene type epoxy resin) manufactured by Nippon Steel Chemical & Material Co., Ltd., "ZX1059" (a mixture of bisphenol A type epoxy resin and bisphenol F 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 resins having a butadiene structure) manufactured by Nippon Soda Co., Ltd., and "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.

[0162] The solid epoxy resin is preferably a solid epoxy resin having three or more epoxy groups per molecule, and more preferably an aromatic solid epoxy resin having three or more epoxy groups per molecule.The solid epoxy resin is preferably a bixylenol type epoxy resin, a naphthalene type epoxy resin, a naphthalene type tetrafunctional epoxy resin, a naphthol novolac type epoxy resin, a cresol novolac 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, or a phenolphthalimidine type epoxy resin.

[0163] Specific examples of solid epoxy resins include DIC Corporation's "HP4032H" (naphthalene-type epoxy resin); DIC Corporation's "HP-4700" and "HP-4710" (naphthalene-type tetrafunctional epoxy resins); DIC Corporation's "N-690" (cresol novolac-type epoxy resin); DIC Corporation's "N-695" (cresol novolac-type epoxy resin); DIC Corporation's "HP-7200," "HP-7200HH," "HP-7200H," and "HP-7200L" (dicyclopentadiene-type epoxy resins); and DIC Corporation's "EXA-7311." "EXA-7311-G3", "EXA-7311-G4", "EXA-7311-G4S", "HP6000" (naphthylene ether type epoxy resin); "EPPN-502H" (trisphenol type epoxy resin) manufactured by Nippon Kayaku Co., Ltd.; "NC7000L" (naphthol novolac type epoxy resin) manufactured by Nippon Kayaku Co., Ltd.; "NC3000H", "NC3000", "NC3000L", "NC3000FH", "NC3100" (biphenyl type epoxy resin) manufactured by Nippon Kayaku Co., Ltd.; "ESN475V", "ESN4" manufactured by Nippon Steel Chemical & Material Co., Ltd. 100V" (naphthalene-type epoxy resin); "ESN485" (naphthol-type epoxy resin) manufactured by Nippon Steel Chemical & Material Co., Ltd.; "ESN375" (dihydroxynaphthalene-type epoxy resin) manufactured by Nippon Steel Chemical & Material Co., Ltd.; "YX4000H", "YX4000", "YX4000HK", and "YL7890" (bixylenol-type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "YL6121" (biphenyl-type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "YX8800" (anthracene-type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "Y" manufactured by Mitsubishi Chemical Corporation Examples include "X7700" (phenol aralkyl type epoxy resin); "PG-100" and "CG-500" manufactured by Osaka Gas Chemicals Co., Ltd.; "YX7760" (bisphenol AF type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "YL7800" (fluorene type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "jER1010" (bisphenol A type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "jER1031S" (tetraphenylethane type epoxy resin) manufactured by Mitsubishi Chemical Corporation; and "WHR991S" (phenolphthalimidine type epoxy resin) manufactured by Nippon Kayaku Co., Ltd.These may be used alone or in combination of two or more.

[0164] When a liquid epoxy resin and a solid epoxy resin are used in combination as the 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.

[0165] The epoxy equivalent of the epoxy resin is preferably 50 g / eq. to 5,000 g / eq., more preferably 60 g / eq. to 3,000 g / eq., even more preferably 80 g / eq. to 2,000 g / eq., and particularly preferably 110 g / eq. to 1,000 g / eq. The epoxy equivalent represents the mass of the resin per equivalent of epoxy groups. This epoxy equivalent can be measured according to JIS K7236.

[0166] As the phenolic resin, a resin having one or more, preferably two or more, hydroxyl groups (phenolic hydroxyl groups) bonded to an aromatic ring such as a benzene ring or a naphthalene ring per molecule can be used. From the viewpoint of heat resistance and water resistance, phenolic resins having a novolac structure are preferred. From the viewpoint of adhesion, nitrogen-containing phenolic resins are preferred, and triazine skeleton-containing phenolic resins are more preferred. Among these, triazine skeleton-containing phenolic novolac resins are preferred from the viewpoint of highly satisfying heat resistance, water resistance, and adhesion.

[0167] Specific examples of phenolic resins include "MEH-7700", "MEH-7810", "MEH-7851", and "MEH-8000H" manufactured by Meiwa Kasei Co., Ltd.; "NHN", "CBN", and "GPH" manufactured by Nippon Kayaku Co., Ltd.; and "SN-170", "SN-180", "SN-190", "SN-475", "SN-485", "SN-495", "SN-495V", and "SN- 375" and "SN-395" manufactured by DIC Corporation; "TD-2090", "TD-2090-60M", "LA-7052", "LA-7054", "LA-1356", "LA-3018", "LA-3018-50P", "LA-1356", "TD2090", and "TD-2090-60M" manufactured by DIC Corporation; and "GDP-6115L", "GDP-6115H", and "ELPC75" manufactured by Gun-ei Chemical Co., Ltd.

[0168] The benzoxazine resin may be a resin having one or more, preferably two or more, benzoxazine rings in one molecule. Specific examples of the benzoxazine resin include "JBZ-OP100D" and "ODA-BOZ" manufactured by JFE Chemical Corporation, "HFB2006M" manufactured by Showa Polymer Co., Ltd., and "Pd", "Fa", and "ALP-d" manufactured by Shikoku Chemicals Corporation.

[0169] The active ester resin may be a resin having one or more active ester groups in one molecule. Among them, preferred active ester resins are compounds having two or more highly reactive ester groups in one molecule, such as phenol esters, thiophenol esters, N-hydroxyamine esters, and esters of heterocyclic hydroxy compounds.

[0170] 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. From the viewpoint of improving heat resistance in particular, an active ester resin obtained from a carboxylic acid compound and a hydroxy compound is preferred, and an active ester resin obtained from a carboxylic acid compound and a phenol compound and / or a naphthol compound is more preferred. Examples of the carboxylic acid compound include benzoic acid, acetic acid, succinic acid, maleic acid, itaconic acid, phthalic acid, isophthalic acid, terephthalic acid, and pyromellitic acid. Examples of phenol compounds or naphthol compounds include hydroquinone, resorcinol, bisphenol A, bisphenol F, bisphenol S, phenolphthalene, methylated bisphenol A, methylated bisphenol F, methylated bisphenol S, phenol, o-cresol, m-cresol, p-cresol, catechol, α-naphthol, β-naphthol, 1,5-dihydroxynaphthalene, 1,6-dihydroxynaphthalene, 2,6-dihydroxynaphthalene, dihydroxybenzophenone, trihydroxybenzophenone, tetrahydroxybenzophenone, phloroglucin, benzenetriol, dicyclopentadiene-type diphenol compounds, and phenol novolak. Here, "dicyclopentadiene-type diphenol compounds" refers to diphenol compounds obtained by condensing one dicyclopentadiene molecule with two phenol molecules.

[0171] 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 among these, a naphthalene-type active ester resin is more preferred. The dicyclopentadiene-type active ester resin is preferably an active ester resin containing a dicyclopentadiene-type diphenol structure.

[0172] Commercially available active ester resins include, for example, "EXB9451", "EXB9460", "EXB9460S", "EXB-8000L", "EXB-8000L-65M", "EXB-8000L-65TM", "HPC-8000L-65TM", "HPC-8000", "HPC-8000-65T", "HPC-8000H", and "HPC-8000H-65TM" (manufactured by DIC Corporation) as active ester resins containing a dicyclopentadiene-type diphenol structure; and "HP-B-8151-62T", "EXB-8100L-65T", "EXB-8150-60T", and "EXB-8150-62" as active ester resins containing a naphthalene structure. Examples of such active ester resins include "EXB9401" (manufactured by DIC Corporation), "EXB-9416-70BK", "HPC-8150-60T", "HPC-8150-62T", and "HPC-8151-62T" (manufactured by DIC Corporation), a phosphorus-containing active ester resin, "EXB9401" (manufactured by DIC Corporation), "DC808" (manufactured by Mitsubishi Chemical Corporation), an active ester resin which is an acetylated product of phenol novolac, "YLH1026", "YLH1030", and "YLH1048" (manufactured by Mitsubishi Chemical Corporation), and an active ester resin containing a styryl group and a naphthalene structure, "PC1300-02-65MA" (manufactured by Air Water Inc.).

[0173] As the cyanate ester resin, a resin having one or more, preferably two or more, cyanate groups in one molecule can be used. Examples of cyanate ester resins include bifunctional cyanate ester resins such as bisphenol A dicyanate, polyphenol cyanate, oligo(3-methylene-1,5-phenylene cyanate), 4,4'-methylenebis(2,6-dimethylphenyl cyanate), 4,4'-ethylidene diphenyl dicyanate, hexafluorobisphenol A dicyanate, 2,2-bis(4-cyanate)phenylpropane, 1,1-bis(4-cyanatephenylmethane), bis(4-cyanate-3,5-dimethylphenyl)methane, 1,3-bis(4-cyanatephenyl-1-(methylethylidene))benzene, bis(4-cyanatephenyl)thioether, and bis(4-cyanatephenyl)ether; multifunctional cyanate ester resins derived from phenol novolac, cresol novolac, and the like; and prepolymers in which these cyanate ester resins are partially triazine converted. Specific examples of cyanate ester resins include "PT30" and "PT60" (phenol novolac type multifunctional cyanate ester resins) manufactured by Lonza, "BA230" and "BA230S75" (prepolymers in which part or all of bisphenol A dicyanate has been triazine converted to a trimer).

[0174] As the carbodiimide resin, a resin having one or more, preferably two or more, carbodiimide structures in one molecule can be used. Specific examples of the carbodiimide resin include aliphatic biscarbodiimides such as tetramethylene-bis(t-butylcarbodiimide) and cyclohexanebis(methylene-t-butylcarbodiimide); aromatic biscarbodiimides such as phenylene-bis(xylylcarbodiimide); aliphatic polycarbodiimides such as polyhexamethylenecarbodiimide, polytrimethylhexamethylenecarbodiimide, polycyclohexylenecarbodiimide, poly(methylenebiscyclohexylenecarbodiimide), and poly(isophoronecarbodiimide); poly(phenylenecarbodiimide), poly(naphthalenecarbodiimide); Examples of polycarbodiimides include aromatic polycarbodiimides such as poly(methylenediphenylenecarbodiimide), poly(tolylenecarbodiimide), poly(methyldiisopropylphenylenecarbodiimide), poly(triethylphenylenecarbodiimide), poly(diethylphenylenecarbodiimide), poly(triisopropylphenylenecarbodiimide), poly(diisopropylphenylenecarbodiimide), poly(xylylenecarbodiimide), poly(tetramethylxylylenecarbodiimide), poly(methylenediphenylenecarbodiimide), and poly[methylenebis(methylphenylene)carbodiimide]. Commercially available carbodiimide resins include, for example, "Carbodilite V-02B," "Carbodilite V-03," "Carbodilite V-04K," "Carbodilite V-05," "Carbodilite V-07," and "Carbodilite V-09" manufactured by Nisshinbo Chemical Inc.; and "Stavaxol P," "Stavaxol P400," and "Hykasil 510" manufactured by Lanxess AG.

[0175] As the acid anhydride resin, a resin having one or more, preferably two or more, acid anhydride groups in one molecule can be used. Specific examples of the acid anhydride resin include phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, methylnadic anhydride, hydrogenated methylnadic anhydride, trialkyltetrahydrophthalic anhydride, dodecenyl succinic anhydride, 5-(2,5-dioxotetrahydro-3-furanyl)-3-methyl-3-cyclohexene-1,2-dicarboxylic anhydride, trimellitic anhydride, pyromellitic anhydride, and benzophenonetetracarboxylic dianhydride. Examples of suitable anhydrides include anhydrides, biphenyltetracarboxylic dianhydride, naphthalenetetracarboxylic dianhydride, oxydiphthalic dianhydride, 3,3'-4,4'-diphenylsulfonetetracarboxylic dianhydride, 1,3,3a,4,5,9b-hexahydro-5-(tetrahydro-2,5-dioxo-3-furanyl)-naphtho[1,2-C]furan-1,3-dione, ethylene glycol bis(anhydrotrimellitate), and polymeric anhydrides such as styrene-maleic acid resins, which are copolymers of styrene and maleic acid. Commercially available acid anhydride resins include, for example, "HNA-100," "MH-700," "MTA-15," "DDSA," and "OSA" manufactured by New Japan Chemical Co., Ltd.; "YH-306" and "YH-307" manufactured by Mitsubishi Chemical Corporation; "HN-2200" and "HN-5500" manufactured by Resonac Corporation; and "EF-30," "EF-40," "EF-60," and "EF-80" manufactured by Cray Valley Chemical Industries, Ltd.

[0176] The amine resin may be a resin having one or more, preferably two or more, amino groups in one molecule. Examples of the amine resin include aliphatic amines, polyether amines, alicyclic amines, and aromatic amines, with aromatic amines being preferred. The amine resin is preferably a primary amine or secondary amine, with primary amines being more preferred. Specific examples of the amine resin include 4,4'-methylenebis(2,6-dimethylaniline), 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenyl sulfone, 3,3'-diaminodiphenyl sulfone, m-phenylenediamine, m-xylylenediamine, diethyltoluenediamine, 4,4'-diaminodiphenyl ether, 3,3'-dimethyl-4,4'-diaminobiphenyl, 2,2'-dimethyl-4,4'-diaminobiphenyl, 3,3'-dihydroxybenzidine, and 2,2-bis(3-amino-4-hydroxyphenyl)propanol. Examples of suitable bis(4-aminophenoxy)benzene include bis(4-aminophenyl)propane, 3,3-dimethyl-5,5-diethyl-4,4-diphenylmethanediamine, 2,2-bis(4-aminophenyl)propane, 2,2-bis(4-(4-aminophenoxy)phenyl)propane, 1,3-bis(3-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, 1,4-bis(4-aminophenoxy)benzene, 4,4'-bis(4-aminophenoxy)biphenyl, bis(4-(4-aminophenoxy)phenyl)sulfone, and bis(4-(3-aminophenoxy)phenyl)sulfone. Commercially available amine-based resins include, for example, "SEIKACURE-S" manufactured by Seika Corporation; "KAYABOND C-200S," "KAYABOND C-100," "KAYAHARD AA," "KAYAHARD AB," and "KAYAHARD AS" manufactured by Nippon Kayaku Co., Ltd.; "Epicure W" manufactured by Mitsubishi Chemical Corporation; and "DTDA" manufactured by Sumitomo Seika Chemicals Co., Ltd.

[0177] In one example, the active group equivalent of the (D) thermosetting resin is preferably 50 g / eq. to 3000 g / eq., more preferably 100 g / eq. to 1000 g / eq., even more preferably 100 g / eq. to 500 g / eq., and particularly preferably 100 g / eq. to 300 g / eq. The active group equivalent represents the mass of the resin per equivalent of the active group.

[0178] For example, the weight average molecular weight (Mw) of the (D) thermosetting resin is preferably in the range of 100 to 5,000, more preferably 250 to 3,000, and even more preferably 400 to 1,500. The weight average molecular weight can be measured by gel permeation chromatography (GPC) as a polystyrene-equivalent value.

[0179] The amount of the (D) thermosetting resin is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, and even more preferably 1% by mass or more, relative to 100% by mass of the nonvolatile components in the thermosetting resin composition, and is preferably 20% by mass or less, more preferably 10% by mass or less, and even more preferably 6% by mass or less.

[0180] The amount of the (D) thermosetting resin is preferably 0.1% by mass or more, more preferably 1% by mass or more, and even more preferably 2% by mass or more, relative to 100% by mass of the resin components in the thermosetting resin composition, and is preferably 40% by mass or less, more preferably 30% by mass or less, and even more preferably 20% by mass or less.

[0181] <(E) Polymer resin> The thermosetting resin composition according to this embodiment may contain a polymer resin (E) as an optional component. Unless otherwise specified, the polymer resin (E) as component (E) does not include those corresponding to the above-mentioned components (A) to (D).

[0182] The weight-average molecular weight of the (E) polymer resin is usually greater than 5,000, preferably greater than 8,000, more preferably greater than 10,000, even more preferably greater than 20,000, and preferably less than 100,000, more preferably less than 70,000, even more preferably less than 60,000. The weight-average molecular weight of the (E) polymer resin can be measured as a polystyrene-equivalent value by GPC. Specifically, the polystyrene-equivalent weight-average molecular weight of the resin can be measured at a column temperature of 40°C using a Shimadzu LC-9A / RID-6A measuring device, a Showa Denko Shodex K-800P / K-804L / K-804L column, and chloroform or the like as the mobile phase, and calculated using a calibration curve of standard polystyrene.

[0183] Examples of (E) polymer resins include oxazoline group-containing resins, phenoxy resins, polybutadiene resins, polyimide resins, polyvinyl acetal resins, polyolefin resins, polyamideimide resins, polyetherimide resins, polysulfone resins, polyethersulfone resins, polyphenylene ether resins, polycarbonate resins, polyetheretherketone resins, and polyester resins. Among these, oxazoline group-containing resins, phenoxy resins, polybutadiene resins, and polyimide resins are preferred. One type of polymer resin may be used alone, or two or more types may be used in combination.

[0184] The oxazoline group-containing resin can be obtained by polymerizing an addition-polymerizable oxazoline compound (vinyloxazoline skeleton-containing monomer) such as 2-isopropenyl-2-oxazoline, 5-methyl-2-isopropenyl-2-oxazoline, 4,4-dimethyl-2-isopropenyl-2-oxazoline, 4-methyl-2-isopropenyl-2-oxazoline, 4,4,5-trimethyl-2-isopropenyl-2-oxazoline, 2-vinyl-2-oxazoline, 5-methyl-2-vinyl-2-oxazoline, 4,4-dimethyl-2-vinyl-2-oxazoline, 4-methyl-2-vinyl-2-oxazoline, or 4,4,5-trimethyl-2-vinyl-2-oxazoline. Furthermore, the oxazoline group-containing resin may be copolymerized with any monomer, such as a styrene-based monomer such as styrene, α-methylstyrene, 4-methylstyrene, 3-methylstyrene, 2-methylstyrene, 4-ethylstyrene, 4-tert-butylstyrene, p-divinylbenzene, m-divinylbenzene, etc. A specific example of the oxazoline group-containing resin is "PX-3-RP-61" manufactured by Nippon Shokubai Co., Ltd.

[0185] Examples of phenoxy resins include phenoxy resins having one or more skeletons selected from the group consisting of bisphenol A, bisphenol F, bisphenol S, bisphenolacetophenone, novolac, biphenyl, fluorene, dicyclopentadiene, norbornene, naphthalene, anthracene, adamantane, terpene, and trimethylcyclohexane. The terminal of the phenoxy resin may be any functional group such as a phenolic hydroxyl group or an epoxy group. Specific examples of phenoxy resins include "1256" and "4250" manufactured by Mitsubishi Chemical Corporation (both of which are phenoxy resins containing a bisphenol A skeleton); "YX8100" manufactured by Mitsubishi Chemical Corporation (phenoxy resin containing a bisphenol S skeleton); "YX6954" manufactured by Mitsubishi Chemical Corporation (phenoxy resin containing a bisphenol acetophenone skeleton); "FX280" and "FX293" manufactured by Nippon Steel Chemical & Material Co., Ltd.; and "YX7200B35," "YL7500BH30," "YX6954BH30," "YX7553BH30," "YL7769BH30," "YL6794," "YL7213," "YL7290," and "YL7482" manufactured by Mitsubishi Chemical Corporation.

[0186] Examples of polybutadiene resins include hydrogenated polybutadiene skeleton-containing resins, hydroxy group-containing polybutadiene resins, phenolic hydroxy group-containing polybutadiene resins, carboxy group-containing polybutadiene resins, acid anhydride group-containing polybutadiene resins, epoxy group-containing polybutadiene resins, isocyanate group-containing polybutadiene resins, urethane group-containing polybutadiene resins, polyphenylene ether-polybutadiene resins, etc. Polybutadiene resins whose molecular ends are blocked with phenol resins may also be used.

[0187] The polyimide resin may be a resin having an imide structure (preferably a cyclic imide structure), such as an imide compound of an acid anhydride and a diamine compound; an imide compound of an acid anhydride and a diisocyanate compound; etc. Among these, an imide compound of an acid anhydride and a diamine compound is preferred. The polyimide resin may also contain an indane skeleton such as a trimethylindane skeleton, for example, a structural unit formed by polymerization of a diamine compound may contain an indane skeleton.

[0188] As the acid anhydride for producing the polyimide resin, tetracarboxylic acid anhydrides are preferred. Examples of tetracarboxylic acid anhydrides include aromatic tetracarboxylic acid dianhydrides and aliphatic tetracarboxylic acid dianhydrides, with aromatic tetracarboxylic acid dianhydrides being preferred. Examples of aromatic tetracarboxylic acid dianhydrides include benzenetetracarboxylic acid dianhydride, naphthalenetetracarboxylic acid dianhydride, anthracenetetracarboxylic acid dianhydride, and diphthalic acid dianhydride, with diphthalic acid dianhydride being preferred. Examples of diphthalic acid dianhydrides include 3,3',4,4'-benzophenonetetracarboxylic acid dianhydride, 3,3',4,4'-diphenylethertetracarboxylic acid dianhydride, 3,3',4,4'-diphenylsulfonetetracarboxylic acid dianhydride, 3,3',4,4'-biphenyltetracarboxylic acid dianhydride, 2,2',3,3'-biphenyltetracarboxylic acid dianhydride, and 2,3,3',4'-biphenyltetracarboxylic acid dianhydride. carboxylic dianhydride, 2,3,3',4'-benzophenonetetracarboxylic dianhydride, 2,3,3',4'-diphenylethertetracarboxylic dianhydride, 2,3,3',4'-diphenylsulfonetetracarboxylic dianhydride, 2,2'-bis(3,4-dicarboxyphenoxyphenyl)sulfone dianhydride, 4,4'-oxydiphthalic anhydride, methylene-4,4'-diphthalic dianhydride, 1,1-ethynylidene-4 ,4'-Diphthalic dianhydride, 2,2-propylidene-4,4'-diphthalic dianhydride, 1,2-ethylene-4,4'-diphthalic dianhydride, 1,3-trimethylene-4,4'-diphthalic dianhydride, 1,4-tetramethylene-4,4'-diphthalic dianhydride, 1,5-pentamethylene-4,4'-diphthalic dianhydride, 1,3-bis(3,4-dicarboxyphenyl)benzene dianhydride, 1,4-bis(3,4-dicarboxyphenyl)benzene dianhydride Examples of the dianhydride include 1,3-bis(3,4-dicarboxyphenoxy)benzene dianhydride, 1,4-bis(3,4-dicarboxyphenoxy)benzene dianhydride, 2,2-bis(2,3-dicarboxyphenyl)propane dianhydride, 2,2-bis(3,4-dicarboxyphenyl)propane dianhydride, and 4,4'-(4,4'-isopropylidenediphenoxy)bisphthalic dianhydride.

[0189] Examples of diamine compounds for producing polyimide resins include aliphatic diamine compounds and aromatic diamine compounds, with aromatic diamine compounds being preferred. Examples of the dianiline compound include 4,4'-diamino-2,2'-ditrifluoromethyl-1,1'-biphenyl, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl sulfide, 4-aminophenyl 4-aminobenzoate, 1,3-bis(3-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, 1,4-bis(4-aminophenoxy)benzene, 2,2-bis(4-aminophenyl)propane, 4,4'-(hexafluoroisopropylidene)dianiline, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, [4-(4-aminophenoxy)phenyl]hexafluoropropane, α,α-bis[4-(4-aminophenoxy)phenyl]-1,3-diisopropylbenzene, α,α-bis[4-(4-aminophenoxy)phenyl]-1,4-diisopropylbenzene, 4,4'-(9-fluorenylidene)dianiline, 2,2-bis(3-methyl-4-aminophenyl)propane, 2,2-bis(3-methyl-4-aminophenyl)benzene, 4,4'-diamino-3,3'-dimethyl-1,1'-biphenyl, 4,4'-diamino-2,2'-dimethyl-1,1'-biphenyl, 9,9'-bis(3-methyl-4-aminophenyl)fluorene, 5-(4-aminophenoxy)-3-[4-(4-aminophenoxy)phenyl]-1,1,3-trimethylindane, and the like.

[0190] Commercially available examples of polyimide resins include "Rikacoat SN20" and "Rikacoat PN20" manufactured by New Japan Chemical Co., Ltd. Other examples of polyimide resins include linear polyimides obtained by reacting bifunctional hydroxyl-terminated polybutadiene, a diisocyanate compound, and a tetrabasic acid anhydride (as described in JP-A No. 2006-37083), and modified polyimides such as polysiloxane skeleton-containing polyimides (as described in JP-A Nos. 2002-12667 and 2000-319386).

[0191] The (E) polymer resin may contain an elastomer. The elastomer is a flexible resin, preferably a resin with rubber elasticity or a resin that exhibits rubber elasticity by polymerizing with other components. Examples of rubber elasticity include resins that exhibit an elastic modulus of 1 GPa or less when subjected to a tensile test in accordance with Japanese Industrial Standards (JIS K7161) at a temperature of 25°C and a humidity of 40% RH.

[0192] The elastomer is preferably one or more types selected from resins having a glass transition temperature (Tg) of 25°C or less and resins that are liquid at 25°C or less. The glass transition temperature of resins having a glass transition temperature (Tg) of 25°C or less is preferably 20°C or less, more preferably 15°C or less. The lower limit of the glass transition temperature is not particularly limited, but is usually -15°C or higher. Furthermore, resins that are liquid at 25°C are preferably resins that are liquid at 20°C or less, more preferably resins that are liquid at 15°C or less. The glass transition temperature can be measured by DSC (differential scanning calorimetry).

[0193] The (E) polymer resin may be included in the thermosetting resin composition in a state compatible with resin components other than the (E) polymer resin. Such a compatible (E) polymer resin is usually included in the cured product in a state compatible with resin components other than the (E) polymer resin. Alternatively, the (E) polymer resin may be included in the thermosetting resin composition in a particulate state in a state in which it is not compatible with resin components other than the (E) polymer resin. Such particulate (E) polymer resin is usually included in the cured product in a particulate state in which it is not compatible with resin components other than the (E) polymer resin. Furthermore, a particulate (E) polymer resin compatible with resin components other than the (E) polymer resin may be used in combination with a particulate (E) polymer resin.

[0194] Examples of particulate (E) polymer resins include rubber particles, polyamide microparticles, silicone particles, and core-shell particles. Among these, rubber particles and core-shell particles are preferred, with core-shell particles being more preferred. Core-shell particles are particulate polymer resins comprising a core particle and one or more shell layers covering the core particle. Core-shell particles are preferably core-shell graft copolymer particles comprising a core particle containing a resin and a shell portion formed by graft copolymerizing a copolymerizable monomer component with the resin contained in the core particle. Here, the term "core-shell" does not necessarily refer only to particles in which the core particle and the shell portion are clearly distinguishable, but also encompasses particles in which the boundary between the core particle and the shell portion is unclear. Furthermore, the core particle does not necessarily have to be completely covered by the shell portion.

[0195] Commercially available core-shell graft copolymer particles include, for example, "CHT" manufactured by Samsung SDI; "B602" manufactured by Techno UMG; "Paraloid EXL2602," "Paraloid EXL2603," "Paraloid EXL2655," "Paraloid EXL2311," "Paraloid EXL2313," "Paraloid EXL2315," "Paraloid KM330," "Paraloid KM336P," and "Paraloid KCZ201" manufactured by Dow Chemical Japan; "Metablen C-223A," "Metablen E-901," "Metablen S-2001," "Metablen W-450A," and "Metablen SRK-200" manufactured by Mitsubishi Rayon; and "Kane Ace M-511," "Kane Ace M-600," "Kane Ace M-400," "Kane Ace M-580," and "Kane Ace MR-01" manufactured by Kaneka Corporation.

[0196] The amount of the (E) polymer resin 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 nonvolatile components in the thermosetting resin composition, and is preferably 40% by mass or less, more preferably 30% by mass or less, and even more preferably 20% by mass or less.

[0197] The amount of the (E) polymer resin is preferably 0.1% by mass or more, more preferably 1% by mass or more, and even more preferably 2% by mass or more, relative to 100% by mass of the resin components in the thermosetting resin composition, and is preferably 60% by mass or less, more preferably 50% by mass or less, and even more preferably 40% by mass or less.

[0198] <(F) Thermal polymerization initiator> The thermosetting resin composition according to the present embodiment may contain a thermal polymerization initiator (F) as an optional component. The thermal polymerization initiator (F) as component (F) can promote the reaction between the internally reactive silane compound (A) and the radically reactive resin (B) during heating, thereby significantly achieving the effects of the present invention.

[0199] As the (F) thermal polymerization initiator, a compound capable of generating free radicals upon heating is usually used. Examples of the (F) thermal polymerization initiator include peroxide-based radical polymerization initiators and azo-based radical polymerization initiators, with peroxide-based radical polymerization initiators being preferred.

[0200] 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-butylperoxyisopropyl monocarbonate, tert-butylperoxy-2-ethylhexanoate, tert-butylperoxyneodecanoate, 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; and the like.

[0201] 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], and 2,2'-azobis[2-methyl-N-[1,1-bis(hydroxymethyl)-2-hydroxyethyl]propionamide]. azoamide 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.

[0202] Commercially available (F) thermal 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 Corp. One type of (F) thermal polymerization initiator may be used alone, or two or more types may be used in combination.

[0203] The amount of the (F) thermal polymerization initiator is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, even more preferably 0.1% by mass or more, relative to 100% by mass of the nonvolatile components in the thermosetting resin composition, and is preferably 5% by mass or less, more preferably 2% by mass or less, even more preferably 1% by mass or less.

[0204] The amount of the (F) thermal polymerization initiator is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and even more preferably 0.5% by mass or more, relative to 100% by mass of the resin component in the thermosetting resin composition, and is preferably 10% by mass or less, more preferably 5% by mass or less, and even more preferably 2% by mass or less.

[0205] <(G) Curing accelerator> The thermosetting resin composition according to this embodiment may contain a (G) curing accelerator as an optional component. The (G) curing accelerator as component (G) does not include components (A) to (F) described above. The (G) curing accelerator acts as a catalyst for the reaction of the (D) thermosetting resin, thereby accelerating the curing of the thermosetting resin composition.

[0206] Examples of the (G) curing accelerator include phosphorus-based curing accelerators, urea-based curing accelerators, guanidine-based curing accelerators, imidazole-based curing accelerators, metal-based curing accelerators, amine-based curing accelerators, etc. One type of (G) curing accelerator may be used alone, or two or more types may be used in combination.

[0207] Examples of the phosphorus-based curing accelerator include aliphatic phosphonium salts such as tetrabutylphosphonium bromide, tetrabutylphosphonium chloride, tetrabutylphosphonium acetate, tetrabutylphosphonium decanoate, tetrabutylphosphonium laurate, bis(tetrabutylphosphonium)pyromellitate, tetrabutylphosphonium hydrogenhexahydrophthalate, tetrabutylphosphonium 2,6-bis[(2-hydroxy-5-methylphenyl)methyl]-4-methylphenolate, and di-tert-butyldimethylphosphonium tetraphenylborate; methyltriphenylphosphonium bromide, ethyltriphenylphosphonium bromide, propyltriphenylphosphonium bromide, butyltriphenylphosphonium bromide, benzyltriphenylphosphonium chloride, tetraphenylphosphonium bromide, p-tolyltriphenylphosphonium tetra-p-tolylborate, and tetraphenylphosphonium tetra-p-tolylborate. aromatic phosphonium salts such as tetraphenylborate, tetraphenylphosphonium tetra-p-tolylborate, triphenylethylphosphonium tetraphenylborate, tris(3-methylphenyl)ethylphosphonium tetraphenylborate, tris(2-methoxyphenyl)ethylphosphonium tetraphenylborate, (4-methylphenyl)triphenylphosphonium thiocyanate, tetraphenylphosphonium thiocyanate, and butyltriphenylphosphonium thiocyanate; aromatic phosphine-borane complexes such as triphenylphosphine-triphenylborane; aromatic phosphine-quinone adducts such as triphenylphosphine-p-benzoquinone adduct; aliphatic phosphines such as tributylphosphine, tri-tert-butylphosphine, trioctylphosphine, di-tert-butyl(2-butenyl)phosphine, di-tert-butyl(3-methyl-2-butenyl)phosphine, and tricyclohexylphosphine;Dibutylphenylphosphine, di-tert-butylphenylphosphine, methyldiphenylphosphine, ethyldiphenylphosphine, butyldiphenylphosphine, diphenylcyclohexylphosphine, triphenylphosphine, tri-o-tolylphosphine, tri-m-tolylphosphine, tri-p-tolylphosphine, tris(4-ethylphenyl)phosphine, tris(4-propylphenyl)phosphine, tris(4-isopropylphenyl)phosphine, tris(4-butylphenyl)phosphine, tris(4-tert-butylphenyl)phosphine, tris(2,4-dimethylphenyl)phosphine, tris(2,5-dimethylphenyl)phosphine, tris(2,6-dimethylphenyl)phosphine aromatic phosphines such as benzene, tris(3,5-dimethylphenyl)phosphine, tris(2,4,6-trimethylphenyl)phosphine, tris(2,6-dimethyl-4-ethoxyphenyl)phosphine, tris(2-methoxyphenyl)phosphine, tris(4-methoxyphenyl)phosphine, tris(4-ethoxyphenyl)phosphine, tris(4-tert-butoxyphenyl)phosphine, diphenyl-2-pyridylphosphine, 1,2-bis(diphenylphosphino)ethane, 1,3-bis(diphenylphosphino)propane, 1,4-bis(diphenylphosphino)butane, 1,2-bis(diphenylphosphino)acetylene, and 2,2'-bis(diphenylphosphino)diphenyl ether;

[0208] Examples of the urea-based curing accelerator include 1,1-dimethylurea; aliphatic dimethylureas such as 1,1,3-trimethylurea, 3-ethyl-1,1-dimethylurea, 3-cyclohexyl-1,1-dimethylurea, and 3-cyclooctyl-1,1-dimethylurea; 3-phenyl-1,1-dimethylurea, 3-(4-chlorophenyl)-1,1-dimethylurea, 3-(3,4-dichlorophenyl)-1,1-dimethylurea, 3-(3-chloro-4-methylphenyl)-1,1-dimethylurea, 3-(2-methylphenyl)-1,1-dimethylurea, 3-(4-methylphenyl)-1,1-dimethylurea, and 3-(3,4-dimethylphenyl)-1,1-dimethylurea. aromatic dimethylureas such as toluene bis(dimethylurea), 3-(4-isopropylphenyl)-1,1-dimethylurea, 3-(4-methoxyphenyl)-1,1-dimethylurea, 3-(4-nitrophenyl)-1,1-dimethylurea, 3-[4-(4-methoxyphenoxy)phenyl]-1,1-dimethylurea, 3-[4-(4-chlorophenoxy)phenyl]-1,1-dimethylurea, 3-[3-(trifluoromethyl)phenyl]-1,1-dimethylurea, N,N-(1,4-phenylene)bis(N',N'-dimethylurea), and N,N-(4-methyl-1,3-phenylene)bis(N',N'-dimethylurea) [toluene bisdimethylurea].

[0209] Examples of guanidine curing accelerators include dicyandiamide, 1-methylguanidine, 1-ethylguanidine, 1-cyclohexylguanidine, 1-phenylguanidine, 1-(o-tolyl)guanidine, dimethylguanidine, diphenylguanidine, trimethylguanidine, tetramethylguanidine, pentamethylguanidine, 1,5,7-triazabicyclo[4.4.0]dec-5-ene, 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene, 1-methylbiguanide, 1-ethylbiguanide, 1-n-butylbiguanide, 1-n-octadecylbiguanide, 1,1-dimethylbiguanide, 1,1-diethylbiguanide, 1-cyclohexylbiguanide, 1-allylbiguanide, 1-phenylbiguanide, and 1-(o-tolyl)biguanide.

[0210] Examples of the imidazole curing accelerator include 2-methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 1,2-dimethylimidazole, 2-ethyl-4-methylimidazole, 1,2-dimethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 1-benzyl-2-methylimidazole, and 1-benzyl-2-methylimidazole. Phenylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-undecylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 1-cyanoethyl-2-phenylimidazole, 1-cyanoethyl-2-undecylimidazole, 1-cyanoethyl-2-phenylimidazolium trimellitate, 1-cyanoethyl-2-phenylimidazolium trimellitate, 2,4-diamino-6-[2'-methylimidazolyl -(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-undecylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-ethyl-4'-methylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine isocyanuric acid adduct, 2-phenylimidazole isocyanuric acid adduct Examples of imidazole compounds include 2-phenyl-4,5-dihydroxymethylimidazole, 2-phenyl-4-methyl-5-hydroxymethylimidazole, 2,3-dihydro-1H-pyrrolo[1,2-a]benzimidazole, 1-dodecyl-2-methyl-3-benzylimidazolium chloride, 2-methylimidazoline, and 2-phenylimidazoline, as well as adducts of imidazole compounds with epoxy resins. Commercially available imidazole curing accelerators include "1B2PZ," "2E4MZ," "2MZA-PW," "2MZ-OK," "2MA-OK," "2MA-OK-PW," "2PHZ," "2PHZ-PW," "Cl1Z," "Cl1Z-CN," "Cl1Z-CNS," and "C11Z-A" manufactured by Shikoku Chemicals Corporation; and "P200-H50" manufactured by Mitsubishi Chemical Corporation.

[0211] Examples of metal-based curing accelerators include organometallic complexes or organometallic salts of metals such as cobalt, copper, zinc, iron, nickel, manganese, and tin. Specific examples of organometallic complexes include organic cobalt complexes such as cobalt(II) acetylacetonate and cobalt(III) acetylacetonate, organic copper complexes such as copper(II) acetylacetonate, organic zinc complexes such as zinc(II) acetylacetonate, organic iron complexes such as iron(III) acetylacetonate, organic nickel complexes such as nickel(II) acetylacetonate, and organic manganese complexes such as manganese(II) acetylacetonate. Examples of organometallic salts include zinc octoate, tin octoate, zinc naphthenate, cobalt naphthenate, tin stearate, and zinc stearate.

[0212] Examples of the amine curing accelerator include trialkylamines such as triethylamine and tributylamine, 4-dimethylaminopyridine, benzyldimethylamine, 2,4,6-tris(dimethylaminomethyl)phenol, 1,8-diazabicyclo(5,4,0)-undecene, etc. Commercially available amine curing accelerators may be used, such as "MY-25" manufactured by Ajinomoto Fine-Techno Co., Inc.

[0213] The amount of (G) curing accelerator is preferably 0.01% by mass or more, more preferably 0.02% by mass or more, even more preferably 0.05% by mass or more, and is preferably 2% by mass or less, more preferably 1% by mass or less, even more preferably 0.1% by mass or less, relative to 100% by mass of non-volatile components in the thermosetting resin composition.

[0214] The amount of (G) curing accelerator is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, even more preferably 0.2% by mass or more, relative to 100% by mass of the resin component in the thermosetting resin composition, and is preferably 5% by mass or less, more preferably 1% by mass or less, even more preferably 0.5% by mass or less.

[0215] <(H) Optional Additives> The thermosetting resin composition according to this embodiment may further contain (H) an optional additive as an optional component. The optional additive (H) as component (H) does not include those corresponding to the above-mentioned components (A) to (G). Examples of the optional additive (H) include organometallic compounds such as organocopper compounds, organozinc compounds, and organocobalt compounds; colorants such as phthalocyanine blue, phthalocyanine green, iodine green, diazo yellow, crystal violet, titanium oxide, and carbon black; polymerization inhibitors such as hydroquinone, catechol, pyrogallol, and phenothiazine; leveling agents such as silicone-based leveling agents and acrylic polymer-based leveling agents; thickeners such as bentone and montmorillonite; antifoaming agents such as silicone-based antifoaming agents, acrylic-based antifoaming agents, fluorine-based antifoaming agents, and vinyl resin-based antifoaming agents; ultraviolet absorbers such as benzotriazole-based ultraviolet absorbers; adhesion improvers such as urea silanes; triazole-based adhesion promoters, tetrazole-based adhesion promoters, and triazine-based adhesion promoters. 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.

[0216] The thermosetting resin composition preferably does not substantially contain a photopolymerization initiator such as a photoacid generator or a photoradical generator. Specifically, when the resin component in the thermosetting resin composition is taken as 100% by mass, the amount of the photopolymerization initiator is preferably less than 0.1% by mass, 0.05% by mass or less, 0.04% by mass or less, 0.02% by mass or less, 0.01% by mass or less, less than 0.01% by mass, 0.005% by mass or less, 0.001% by mass or less, or less than 0.001% by mass.

[0217] <(I) Solvent> The thermosetting resin composition may further contain (I) a solvent as an optional volatile component in addition to the nonvolatile components (A) to (H) described above. The (I) solvent is typically an organic solvent. Examples of organic solvents include ketone-based solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; ester-based solvents such as methyl acetate, ethyl acetate, butyl acetate, isobutyl acetate, isoamyl acetate, methyl propionate, ethyl propionate, and γ-butyrolactone; ether-based solvents such as tetrahydropyran, tetrahydrofuran, 1,4-dioxane, diethyl ether, diisopropyl ether, dibutyl ether, diphenyl ether, and anisole; alcohol-based solvents such as methanol, ethanol, propanol, butanol, and ethylene glycol; 2-ethoxyethyl acetate, propylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, ethyl diglycol acetate, γ-butyrolactone, and methyl methoxypropionate. Examples of suitable solvents include ether ester solvents such as ethyl acetate; ester alcohol solvents such as methyl lactate, ethyl lactate, and methyl 2-hydroxyisobutyrate; ether alcohol solvents such as 2-methoxypropanol, 2-methoxyethanol, 2-ethoxyethanol, propylene glycol monomethyl ether, and diethylene glycol monobutyl ether (butyl carbitol); amide solvents such as N,N-dimethylformamide, N,N-dimethylacetamide, and N-methyl-2-pyrrolidone; sulfoxide solvents such as dimethyl sulfoxide; nitrile solvents such as acetonitrile and propionitrile; aliphatic hydrocarbon solvents such as hexane, cyclopentane, cyclohexane, and methylcyclohexane; and aromatic hydrocarbon solvents such as benzene, toluene, xylene, ethylbenzene, and trimethylbenzene. (I) The solvents may be used singly or in combination of two or more.

[0218] The amount of (I) solvent, relative to 100% by mass of all components in the thermosetting resin composition, may be, for example, 60% by mass or less, 40% by mass or less, 30% by mass or less, 20% by mass or less, 15% by mass or less, or 10% by mass or less, or may be 0% by mass.

[0219] <Method for producing thermosetting resin composition> The thermosetting resin composition can be produced, for example, by mixing components that can be contained in the thermosetting resin composition. Therefore, the thermosetting resin composition can be produced by a production method including a step of mixing (A) an internally reactive silane compound and (B) a radically reactive resin. This production method may also include a step of mixing optional components such as components (C) to (I). Components (A) to (I) may be mixed in part or all at the same time, or they may be mixed sequentially.

[0220] In particular, it is preferable that the thermosetting resin composition containing the (C-1) specially treated inorganic filler be produced by a production method including the steps of: mixing (A) an internally reactive silane compound with (C') an inorganic filler before surface treatment to obtain the (C-1) specially treated inorganic filler; and mixing the (C-1) specially treated inorganic filler with the (B) radical-reactive resin.

[0221] (C') Pre-surface-treated inorganic filler refers to an inorganic filler before being subjected to surface treatment with (A) an internally reactive silane compound. "(C') Pre-surface-treated inorganic filler" may be referred to as "(C') Pre-treated filler" hereinafter. (C') Pre-treated filler may be particles that have not been surface-treated with any surface treatment agent. Alternatively, (C') Pre-treated filler may be particles that have been surface-treated with any surface treatment agent.

[0222] The surface treatment of the (C') pre-treatment filler can be carried out by contacting the (C') pre-treatment filler with the (A) internally reactive silane compound. For example, the (C') pre-treatment filler can be stirred while the (A) internally reactive silane compound is supplied to the (C') pre-treatment filler, thereby contacting the (C') pre-treatment filler with the (A) internally reactive silane compound, thereby carrying out the surface treatment. From the viewpoint of carrying out a uniform surface treatment, it is preferable to supply the (A) internally reactive silane compound by spraying.

[0223] After the (C') pre-treatment filler is surface-treated with the (A) internally reactive silane compound to obtain the (C-1) specifically treated inorganic filler, the (C-1) specifically treated inorganic filler may be further surface-treated with an optional surface treatment agent. The surface treatment with the optional surface treatment agent may be carried out, for example, by the same method as the surface treatment with the (A) internally reactive silane compound. Furthermore, the surface treatment with the (A) internally reactive silane compound and the surface treatment with the optional surface treatment agent may be carried out simultaneously.

[0224] After obtaining the (C-1) specially treated inorganic filler, the (C) inorganic filler containing the (C-1) specially treated inorganic filler and the (B) radical-reactive resin, as well as optional components, can be mixed to obtain a thermosetting resin composition. These components may be mixed in part or in whole simultaneously, or sequentially. Furthermore, as described above, the temperature may be appropriately set during the process of mixing the components, and thus heating and / or cooling may be performed temporarily or throughout the process. Furthermore, stirring or shaking may be performed during the process of mixing the components.

[0225] <Characteristics of the thermosetting resin composition and its cured product> The thermosetting resin composition according to this embodiment can usually have a low minimum melt viscosity. Therefore, for example, when a thermosetting resin composition layer is formed on a substrate having wiring on its surface, the wiring on the substrate surface can be satisfactorily embedded in the thermosetting resin composition layer. The specific minimum melt viscosity range of the thermosetting resin composition is preferably 4500 poise or less, more preferably 4200 poise or less, and even more preferably 4000 poise or less. The lower limit can be, for example, 500 poise or more, 1000 poise or more, etc.

[0226] The minimum melt viscosity of the thermosetting resin composition can be determined by measuring the dynamic viscoelastic modulus while raising the temperature from a starting temperature of 60°C to 200°C under the following measurement conditions: a temperature rise rate of 5°C / min, a measurement interval temperature of 2.5°C, a vibration frequency of 1 Hz, and a strain of 5°C, using a dynamic viscoelasticity measuring device. The minimum melt viscosity can be determined as the minimum value of the measured melt viscosities. Specific measurement methods that can be used include those described in the Examples below.

[0227] The thermosetting resin composition according to this embodiment can be cured by heat. Therefore, a cured product of the thermosetting resin composition can be obtained by thermally curing the thermosetting resin composition. Generally, among the components contained in the thermosetting resin composition, volatile components such as (I) solvent can be volatilized by the heat during thermal curing. Therefore, the cured product of the thermosetting resin composition can contain non-volatile components such as components (A) to (H) or reaction products thereof.

[0228] In the cured product of the thermosetting resin composition according to this embodiment, the formation of unevenness can be suppressed. In one example, when a thermosetting resin composition layer containing the thermosetting resin composition is thermally cured to obtain a cured product, the formation of unevenness can be suppressed at least in the center of the layer, and preferably throughout the entire layer. The effect of suppressing unevenness can be evaluated, for example, by the method described in the examples below.

[0229] The cured product of the thermosetting resin composition according to this embodiment typically has excellent dielectric properties, for example, a low dielectric loss tangent. In one example, the dielectric loss tangent of the cured product is preferably 0.0100 or less, more preferably 0.0080 or less, and even more preferably 0.0050 or less. The lower limit of the dielectric loss tangent is not particularly limited, and may be, for example, 0.0010 or more. The dielectric loss tangent of the cured product can be measured by a cavity resonance perturbation method at a measurement frequency of 5.8 GHz and a measurement temperature of 23°C. When the sample is a thermosetting resin composition before curing, the thermosetting resin composition may be heated at 190°C for 90 minutes to obtain a cured product, and the dielectric loss tangent of the cured product may be measured. Specific measurement methods may be those described in the Examples below.

[0230] The cured product of the thermosetting resin composition according to this embodiment typically exhibits excellent mechanical strength. For example, the strength at break of the cured product is preferably 85 MPa or more, more preferably 90 MPa or more, and even more preferably 95 MPa or more. The upper limit of the strength at break is not particularly limited and may be, for example, 150 MPa or less, 140 MPa or less, or 130 MPa or less. Furthermore, for example, the elongation at break of the cured product is preferably 1.3% or more, more preferably 1.4% or more, even more preferably 1.5% or more, and particularly preferably 1.6% or more. The upper limit of the elongation at break is not particularly limited and may be, for example, 5% or less, 4% or less, or 3% or less. The strength at break and elongation at break of the cured product can be measured at a temperature of 23°C by tensile strength measurement using a tensile tester. This measurement is performed in accordance with JIS K7127. When the sample is a thermosetting resin composition before curing, the thermosetting resin composition may be heated at 190°C for 90 minutes to obtain a cured product, and the strength at break and elongation at break of the cured product may be measured. Specific measurement methods may be those described in the Examples below.

[0231] The cured product of the thermosetting resin composition according to this embodiment can usually have high metal foil adhesion. When forming an insulating layer for a circuit board, the insulating layer may be formed from the cured product of the thermosetting resin composition on a conductor layer such as wiring formed on the surface of an inner layer substrate. The conductor layer is generally formed from metal. Therefore, the high metal foil adhesion of the cured product can improve the adhesion between the conductor layer and the insulating layer. In one example, when the copper foil peel strength is measured using the method described in the Examples below, the copper foil peel strength is preferably 0.40 kgf / cm or more, more preferably 0.50 kgf / cm or more, and particularly preferably 0.55 kgf / cm or more. There is no particular upper limit, and it may be, for example, 1 kgf / cm or less or 0.9 kgf / cm or less.

[0232] <Uses of thermosetting resin compositions> The thermosetting resin composition according to this embodiment can be used to form an insulating layer, and is particularly preferably used to form an insulating layer for a circuit board. The thermosetting resin composition can also be used to manufacture a resin sheet. Typically, an insulating layer is formed using this resin sheet. The thermosetting resin composition may also be used for other purposes, such as a solder resist, an underfill material, a die bonding material, a hole-filling resin, a sealing resin, or a component-embedding resin.

[0233] <Resin sheet> A resin sheet according to one embodiment of the present invention includes a support and a thermosetting resin composition layer formed on the support. The thermosetting resin composition layer contains the above-described thermosetting resin composition, and preferably contains only the above-described thermosetting resin composition.

[0234] Since the thermosetting resin composition layer contains the above-mentioned thermosetting resin composition, the formation of unevenness can be suppressed in the cured product obtained by curing the thermosetting resin composition layer of the resin sheet. Therefore, the formation of unevenness can be suppressed in the insulating layer formed by the cured product. Furthermore, since the thermosetting resin composition usually has a low minimum melt viscosity, when laminating the resin sheet and the inner layer substrate, the wiring on the surface of the inner layer substrate can be well embedded by the thermosetting resin composition layer. Furthermore, the formed insulating layer usually has excellent mechanical strength and excellent adhesion to conductor layers such as wiring.

[0235] From the viewpoint of thinning, the thickness of the thermosetting resin composition layer provided in the resin sheet is preferably 200 μm or less, more preferably 150 μm or less, and even more preferably 100 μm or less. The lower limit of the thickness of the thermosetting resin composition layer can be, for example, 1 μm or more, 3 μm or more, 5 μm or more, etc.

[0236] Examples of the support include plastic film, metal foil, and release paper, with plastic film and metal foil being preferred.

[0237] When a film of a plastic material is used as the support, examples of the plastic material include polyesters such as polyethylene terephthalate (hereinafter sometimes abbreviated as "PET") and polyethylene naphthalate (hereinafter sometimes abbreviated as "PEN"), polycarbonate (hereinafter sometimes abbreviated as "PC"), acrylics such as polymethyl methacrylate (PMMA), cyclic polyolefins, triacetyl cellulose (TAC), polyether sulfide (PES), polyether ketone, polyimide, etc. Among these, polyethylene terephthalate and polyethylene naphthalate are preferred, with inexpensive polyethylene terephthalate being particularly preferred.

[0238] When a metal foil is used as the support, examples of the metal foil include copper foil and aluminum foil, with copper foil being preferred. The copper foil may be a foil made of a single metal, copper, or an alloy of copper and another metal (e.g., tin, chromium, silver, magnesium, nickel, zirconium, silicon, titanium, etc.).

[0239] The surface of the support that is to be bonded to the thermosetting resin composition layer may be subjected to a surface treatment such as matte treatment, corona treatment, or antistatic treatment.

[0240] The support may be a support with a release layer, which has a release layer on the surface that bonds to the thermosetting resin composition layer. Examples of the release agent used in the release layer of the support with a release layer include one or more release agents selected from the group consisting of alkyd-based release agents, polyolefin-based release agents, urethane-based release agents, and silicone-based release agents. Commercially available products may be used as the support with a release layer, including PET films having a release layer primarily composed of a silicone-based release agent or an alkyd resin-based release agent, such as "PET501010," "SK-1," "AL-5," and "AL-7" manufactured by Lintec Corporation; "Lumirror T60" manufactured by Toray Industries, Inc.; "Purex" manufactured by Teijin Limited; and "Uni-Peel" manufactured by Unitika Limited.

[0241] The thickness of the support is not particularly limited, but is preferably 1 μm or more, more preferably 5 μm or more, even more preferably 10 μm or more, and is preferably 75 μm or less, more preferably 60 μm or less, even more preferably 50 μm or less. When a support with a release layer is used, it is preferable that the thickness of the entire support with a release layer is within the above range.

[0242] The resin sheet may include any optional member as needed. For example, the resin sheet may include a protective film for protecting the thermosetting resin composition layer. The protective film is usually provided on the surface of the thermosetting resin composition layer that is not bonded to the support (i.e., the surface opposite the support). The thickness of the protective film is not particularly limited, but is, for example, 1 μm to 40 μm. When the protective film is provided, adhesion of dust and scratches to the surface of the thermosetting resin composition layer can be suppressed.

[0243] The resin sheet can be produced, for example, by a method including forming a thermosetting resin composition layer on a support. Specifically, the resin sheet can be produced by applying a liquid (varnish-like) thermosetting resin composition directly or by mixing a solvent and the thermosetting resin composition to prepare a liquid (varnish-like) thermosetting resin composition, applying the liquid (varnish-like) thermosetting resin composition to a support, and then drying it as necessary to form a thermosetting resin composition layer. The solvent may be the same as the solvent (I) described as a component of the thermosetting resin composition.

[0244] The thermosetting resin composition can be applied using a coating device such as a die coater. Drying can be performed by a drying method such as heating or hot air blowing. The drying conditions are not particularly limited, but drying is typically performed so that the solvent content in the thermosetting resin composition layer is 10% by mass or less, preferably 5% by mass or less. Although this may vary depending on the boiling point of the solvent, for example, when a thermosetting resin composition containing 30% by mass to 60% by mass of solvent is used, a thermosetting resin composition layer can be formed by drying at 50°C to 150°C for 3 to 10 minutes.

[0245] The produced resin sheet can be stored by being wound up in a roll. When the resin sheet has a protective film, the resin sheet can usually be used by peeling off the protective film.

[0246] <Circuit board> A circuit board according to one embodiment of the present invention includes a cured product of the thermosetting resin composition described above. Typically, the circuit board includes an insulating layer, and this insulating layer includes a cured product of the thermosetting resin composition. The insulating layer may include only a cured product of the thermosetting resin composition. The thickness of the insulating layer is not particularly limited and may be, for example, in the same range as the thickness of the thermosetting resin composition layer included in the resin sheet.

[0247] Preferably, the circuit board includes an inner layer substrate and the insulating layer is provided on the inner layer substrate. The circuit board may also include a conductor layer. For example, the conductor layer may be provided on an insulating layer. An example of a preferred method for manufacturing a circuit board will be described below.

[0248] A preferred example of a method for manufacturing a circuit board includes the steps of: Step (I) of forming a thermosetting resin composition layer on an inner layer substrate; a step (II) of curing the thermosetting resin composition layer; Includes:

[0249] An "inner layer substrate" is a member that serves as the base material of a circuit board, and examples thereof include glass epoxy substrates, metal substrates, polyester substrates, polyimide substrates, BT resin substrates, and thermosetting polyphenylene ether substrates. The inner layer substrate may have a conductor layer on one or both sides. The conductor layer of the inner layer substrate may be patterned. An inner layer substrate having a conductor layer (circuit) formed on one or both sides of the substrate is sometimes called an "inner layer circuit board." The term "inner layer substrate" also includes intermediate products on which insulating layers and / or conductor layers are to be further formed during the production of a circuit board. In addition, inner layer substrates with built-in components may also be used.

[0250] The thermosetting resin composition layer can be formed on the inner layer substrate by, for example, laminating the resin sheet and the inner layer substrate. The resin sheet and the inner layer substrate are laminated so that the thermosetting resin composition layer of the resin sheet and the inner layer substrate are bonded. This lamination may be performed, for example, by thermocompression bonding the resin sheet to the inner layer substrate from the support side. Examples of a member for thermocompression bonding the resin sheet to the inner layer substrate (hereinafter also referred to as a "thermocompression bonding member") include a heated metal plate (such as a SUS panel) or a metal roll (such as a SUS roll). Note that, rather than pressing the resin sheet directly with the thermocompression bonding member, it is preferable to press it via an elastic material such as heat-resistant rubber so that the resin sheet can sufficiently conform to the surface irregularities of the inner layer substrate.

[0251] The lamination of the inner layer substrate and the resin sheet may be carried out by a vacuum lamination method. In the vacuum lamination method, the thermocompression temperature is preferably in the range of 60°C to 160°C, more preferably 80°C to 140°C, the thermocompression pressure is preferably in the range of 0.098MPa to 1.77MPa, more preferably 0.29MPa to 1.47MPa, and the thermocompression time is preferably in the range of 20 seconds to 400 seconds, more preferably 30 seconds to 300 seconds. The lamination is preferably carried out under reduced pressure conditions of 26.7hPa or less.

[0252] The lamination may be performed using a commercially available vacuum laminator, such as a vacuum pressure laminator manufactured by Meiki Seisakusho Co., Ltd., a vacuum applicator manufactured by Nikko Materials Co., Ltd., or a batch-type vacuum pressure laminator.

[0253] The method for manufacturing a circuit board may include smoothing the resin sheet after lamination under normal pressure (atmospheric pressure), for example, by pressing the resin sheet from the support side with a thermocompression member. The pressing conditions for the smoothing may be the same as those for the thermocompression bonding of the lamination. The smoothing may be performed using a commercially available laminator. The lamination and smoothing may be performed consecutively using the commercially available vacuum laminator.

[0254] The method for producing a circuit board according to this example includes a step (II) of curing the thermosetting resin composition layer after the step (I). By curing the thermosetting resin composition layer in the step (II), an insulating layer can be formed.

[0255] The thermosetting resin composition layer is usually cured by heat curing. The heat curing conditions for the thermosetting resin composition layer may vary depending on the type of thermosetting 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.

[0256] The method for producing a circuit board may include preheating the thermosetting resin composition layer at a temperature lower than the curing temperature before thermally curing the thermosetting resin composition layer. For example, prior to thermally curing the thermosetting resin composition layer, the thermosetting resin composition layer may be preheated for typically 5 minutes or more, preferably 5 minutes to 150 minutes, more preferably 15 minutes to 120 minutes, and even more preferably 15 minutes to 100 minutes, at a temperature of typically 50°C to 150°C, preferably 60°C to 140°C, and more preferably 70°C to 130°C. Preheating is typically performed after step (I). Furthermore, when a smoothing treatment is performed after laminating the inner layer substrate and the resin sheet, preheating can be performed after the smoothing treatment.

[0257] When a resin sheet is used, the method for producing a circuit board may include a step of peeling off the support of the resin sheet after laminating the inner layer substrate and the resin sheet. The peeling off of the support may be performed between steps (I) and (II), or after step (II). Furthermore, when the method for producing a circuit board includes step (III) of forming holes in the insulating layer, step (IV) of roughening the insulating layer, and step (V) of forming a conductor layer, as described below, the peeling off of the support may be performed between steps (II) and (III), between steps (III) and (IV), or between steps (IV) and (V).

[0258] The method for producing a circuit board may include, after step (II), step (III) of forming holes such as via holes or through holes in the insulating layer. The method for forming the holes may be selected depending on factors such as the composition of the thermosetting resin composition used to form the insulating layer. For example, holes may be formed by processing methods such as drilling, laser processing, and plasma processing, with laser processing being preferred. For example, holes may be formed by irradiating the insulating layer with laser light after peeling off the support, or by irradiating the insulating layer with laser light through the support. The dimensions and shape of the holes may be determined appropriately depending on the design of the circuit board.

[0259] The method for manufacturing a circuit board may include a step (IV) of roughening the insulating layer. The roughening treatment can roughen the surface of the insulating layer. The roughening treatment can also remove smears (resin residues) from the insulating layer. Therefore, this roughening treatment is sometimes called a "desmear treatment." For example, when holes are formed in step (III), smears may form in the holes. Therefore, it is preferable to perform the roughening treatment of step (IV) after step (III) to remove the smears.

[0260] The procedure and conditions for the roughening treatment are not particularly limited, and known procedures and conditions that are commonly used when forming an insulating layer for a circuit board can be adopted. For example, the roughening treatment may be performed by subjecting the insulating layer to a swelling treatment using a swelling liquid, an oxidation treatment using an oxidizing agent, and a neutralization treatment using a neutralizing liquid in this order.

[0261] Examples of swelling liquids used in the roughening treatment include alkaline solutions and surfactant solutions, with alkaline solutions being preferred. Examples of the alkaline solution include sodium hydroxide solution and potassium hydroxide solution. Examples of commercially available swelling liquids include "Swelling Dip Securigance P" and "Swelling Dip Securigance SBU" manufactured by Atotech Japan. Swelling treatment using a swelling liquid can be performed by immersing the insulating layer in the swelling liquid at 30°C to 90°C for 1 to 20 minutes. From the viewpoint of suppressing swelling of the resin in the insulating layer to an appropriate level, it is preferable to immerse the insulating layer in the swelling liquid at 40°C to 80°C for 5 to 15 minutes.

[0262] Examples of oxidizing agents used in the roughening treatment include alkaline permanganate solutions prepared by dissolving potassium permanganate or sodium permanganate in an aqueous solution of sodium hydroxide. Oxidation treatment using an oxidizing agent such as alkaline permanganate solution is preferably carried out by immersing the insulating layer in an oxidizing agent solution heated to 60°C to 100°C for 10 to 30 minutes. The concentration of permanganate in the alkaline permanganate solution is preferably 5% by mass to 10% by mass. Commercially available oxidizing agents include alkaline permanganate solutions such as "Concentrate Compact CP" and "Dosing Solution Securigance P" manufactured by Atotech Japan.

[0263] The neutralizing solution used in the roughening treatment is preferably an acidic aqueous solution, and a commercially available product such as "Reduction Solution Securigant P" manufactured by Atotech Japan can be cited as an example. Neutralization treatment using a neutralizing solution can be carried out by immersing the surface that has been oxidized with an oxidizing agent in a neutralizing solution at 30°C to 80°C for 5 to 30 minutes. From the standpoint of workability, a preferred method is to immerse the object that has been oxidized with an oxidizing agent in a neutralizing solution at 40°C to 70°C for 5 to 20 minutes.

[0264] The method for producing a circuit board may include step (V) of forming a conductor layer on the insulating layer. When the method for producing a circuit board includes step (III) or (IV), step (V) of forming a conductor layer is usually preferably carried out after steps (III) and (IV).

[0265] The conductive material used for the conductor layer is not particularly limited. In a preferred embodiment, the conductor layer contains one or more metals selected from the group consisting of gold, platinum, palladium, silver, copper, aluminum, cobalt, chromium, zinc, nickel, titanium, tungsten, iron, tin, and indium. The conductor layer may be a single metal layer or an alloy layer. Examples of alloy layers include layers formed from 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 these, from the viewpoints of versatility in forming the conductor layer, cost, ease of patterning, etc., single metal layers of chromium, nickel, titanium, aluminum, zinc, gold, palladium, silver, or copper, or alloy layers of nickel-chromium alloy, copper-nickel alloy, or copper-titanium alloy are preferred. Single metal layers of chromium, nickel, titanium, aluminum, zinc, gold, palladium, silver, or copper, or alloy layers of nickel-chromium alloy are more preferred, and single metal layers of copper are even more preferred.

[0266] The conductor layer may have a single layer structure or a multi-layer structure including two or more single metal or alloy layers made of different types of metals or alloys. When the conductor layer has a multi-layer structure, the layer in contact with the insulating layer is preferably a single metal layer of chromium, zinc, or titanium, or an alloy layer of a nickel-chromium alloy.

[0267] 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.

[0268] The conductor layer may be formed by plating. For example, a conductor layer having a desired wiring pattern can be formed by plating the surface of the insulating layer using a conventionally known technique such as a semi-additive method or a full-additive method. From the viewpoint of ease of production, the semi-additive method is preferred. An example of forming a conductor layer by a semi-additive method will be described below.

[0269] First, an electroless plated layer (plating seed layer) is formed on the surface of the insulating layer by electroless plating. Next, a mask pattern is formed on the formed electroless plated layer, exposing a portion of the electroless plated layer corresponding to the desired wiring pattern. After forming an electroless plated layer on the exposed electroless plated layer by electrolytic plating, the mask pattern is removed. Thereafter, unnecessary electroless plated layer is removed by etching, thereby forming a conductor layer having the desired wiring pattern.

[0270] As another example, the conductor layer may be formed using a metal foil. When a metal foil is used to form the conductor layer, step (V) is preferably performed between steps (I) and (II). For example, after step (I), the support is removed, and a metal foil is laminated on the exposed surface of the thermosetting resin composition layer. The lamination of the resin composition layer and the metal foil may be performed by a vacuum lamination method. The lamination conditions may be the same as those described for step (I). Next, step (II) is performed to form an insulating layer. Thereafter, a conductor layer having a desired wiring pattern can be formed using the metal foil on the insulating layer by a known technique such as a subtractive method or a modified semi-additive method. The metal foil can be manufactured by a known method such as an electrolytic method or a rolling method. Commercially available metal foils include, for example, HLP foil and JXUT-III foil manufactured by JX Nippon Mining & Smelting Co., Ltd., and 3EC-III foil and TP-III foil manufactured by Mitsui Mining & Smelting Co., Ltd.

[0271] When a conductor layer is formed on an insulating layer, the method for manufacturing a circuit board may include performing an annealing treatment after the formation of the conductor layer. The annealing treatment can improve the adhesion between the insulating layer and the conductor layer. The annealing treatment can be performed, for example, by heating at 150°C to 210°C for 20 to 180 minutes.

[0272] In the method for manufacturing a circuit board, each of the above steps may be performed only once or may be repeated two or more times. For example, steps (I) to (V) may be performed repeatedly to form a circuit board having a multilayer structure, such as a multilayer printed wiring board having a plurality of insulating layers and conductor layers.

[0273] The method for manufacturing a circuit board may further include any optional steps in addition to the steps described above. For example, the method for manufacturing a circuit board may include a step of providing a semiconductor chip so that the semiconductor chip is bonded to the conductor layer. Specifically, when manufacturing a circuit board for a semiconductor chip package including a semiconductor chip, the method for manufacturing a circuit board may include a step of providing the semiconductor chip. The semiconductor chip may be bonded under appropriate conditions that allow conductive connection between the terminal electrodes of the semiconductor chip and the conductor layer formed on the insulating layer. For example, conditions used in flip-chip mounting may be employed. The semiconductor chip may be bonded via an insulating adhesive or by reflow bonding. If necessary, the provided semiconductor chip may be filled with a mold underfill material. The method for manufacturing a circuit board may also include, for example, a step of forming a sealing layer, a step of forming a solder resist layer, and a step of dicing the manufactured circuit board into individual pieces.

[0274] Examples of circuit boards include printed wiring boards and semiconductor chip packages. Examples of semiconductor chip packages include FC-CSP, MIS-BGA package, ETS-BGA package, fan-out type WLP (Wafer Level Package), fan-in type WLP, fan-out type PLP (Panel Level Package), and fan-in type PLP. In these semiconductor chip packages, it is preferable to form a rewiring formation layer using an insulating layer obtained by curing the above-mentioned thermosetting resin composition layer. However, the circuit board is not limited to those exemplified here.

[0275] <Semiconductor device> The circuit board can be used to manufacture a semiconductor device. The semiconductor device includes the circuit board described above. Examples of the semiconductor device include various semiconductor devices used in electrical appliances (e.g., computers, mobile phones, smartphones, tablet devices, wearable devices, digital cameras, medical equipment, and televisions) and vehicles (e.g., motorcycles, automobiles, trains, ships, and aircraft). [Example]

[0276] The present invention will be specifically described below 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 "% by mass", respectively, unless otherwise specified. Furthermore, the temperature and pressure conditions were room temperature (23°C) and atmospheric pressure (1 atm), unless otherwise specified.

[0277] <Synthesis Example 1: Synthesis of Maleimide Resin A> A methyl ethyl ketone solution (70% by mass of non-volatile components) of maleimide resin A synthesized by the method described in Synthesis Example 1 of the Japan Institute of Invention and Innovation's Technical Journal Publication No. 2020-500211 was prepared. This maleimide resin A has a structure represented by the following formula.

[0278] [ka]

[0279] <Synthesis Example 2: Synthesis of styryl resin B> According to Example 1 of WO 2017 / 115813, 3.0 mol (390.6 g) of divinylbenzene, 1.8 mol (229.4 g) of ethylvinylbenzene, 10.2 mol (1066.3 g) of styrene, and 15.0 mol (1532.0 g) of n-propyl acetate were charged into a 5.0 L reactor, and 600 mmol of boron trifluoride diethyl ether complex was added at 70 °C. The reaction was allowed to proceed for 4 hours. After the polymerization solution was terminated with aqueous sodium bicarbonate, the oil layer was washed three times with pure water, and the polymer was recovered by devolatilization under reduced pressure at 60 °C. The resulting product was weighed, confirming that 896.7 g of styryl resin B was obtained. The weight average molecular weight (Mw) of styryl resin B was 41,300.

[0280] <Synthesis Example 3: Synthesis of Elastomer C> A flask equipped with a stirrer, thermometer, and condenser was charged with 271.7 parts by mass of propylene glycol methyl ether acetate (PGMAc), 14.1 parts by mass (0.064 mol) of isophorone diisocyanate (IPDI), and 112.2 parts by mass (0.03 mol) of polybutadiene ("G-3000" manufactured by Nippon Soda Co., Ltd., hydroxyl value: 30 mg KOH / g) containing OH groups at both ends to obtain a mixed solution. The mixed solution was heated to 50°C and then maintained at this temperature for 1 hour. Next, after confirming that the amount of isocyanate groups was below a predetermined value, 145.2 parts by mass (0.09 mol) of an oligophenylene ether resin containing phenolic hydroxyl groups at both ends ("SA90-100" manufactured by Sabic, hydroxyl group equivalent: 807 g / mol) and 1 part by mass (0.003 mol) of benzophenone tetracarboxylic dianhydride (BTDA) were added to the mixed solution. The mixed solution was then heated to 140°C, and the reaction was continued for 4 hours. Characteristic absorption was measured by infrared spectroscopy, and the characteristic absorption of the isocyanate group at 2270 cm was confirmed. -1The reaction was terminated when it was confirmed that the absorption peak had completely disappeared and the increase in viscosity had subsided. In this way, a solution of Elastomer C was obtained, which had a structure in which the molecular ends were blocked with a phenolic resin (oligophenylene ether resin containing phenolic hydroxyl groups at both ends). The content of non-volatile components in the solution was 50% by mass. The weight-average molecular weight of Elastomer C was 15,000.

[0281] <Synthesis Example 4: Synthesis of Polyimide Resin D> A 500 mL separable flask was prepared, equipped with a water content receiver connected to a reflux condenser, a nitrogen inlet tube, and a stirrer. 20.3 g of 4,4'-oxydiphthalic anhydride (ODPA), 200 g of γ-butyrolactone, 20 g of toluene, and 29.6 g of 5-(4-aminophenoxy)-3-[4-(4-aminophenoxy)phenyl]-1,1,3-trimethylindane were added to the flask and stirred at 45°C for 2 hours under a nitrogen stream. The reaction solution was then heated and maintained at approximately 160°C, while the condensed water was azeotropically removed with toluene under a nitrogen stream. It was confirmed that the specified amount of water had accumulated in the water content receiver and that no water was leaking out. After confirmation, the reaction solution was further heated and stirred at 200°C for 1 hour. The mixture was then cooled to obtain a polyimide resin solution (20% by mass of non-volatile components) containing polyimide resin D having a 1,1,3-trimethylindane skeleton. The obtained polyimide resin D had a repeating unit represented by the following formula (X1) and a repeating unit represented by the following formula (X2). The weight-average molecular weight of the polyimide resin D was 12,000.

[0282] [ka]

[0283] <Production Example 1. Production of Silica 1 Surface-Treated with Internally Reactive Silane Compound> Spherical silica (average particle size 0.5 μm, specific surface area 5.8 m 2100 parts by mass of silica 1 (1 / g, manufactured by Admatechs Co., Ltd., "SO-C2") was placed in a Henschel-type mixer. 0.8 parts by mass of an internally reactive silane compound (manufactured by Shin-Etsu Chemical Co., Ltd., "X-12-1333A") was sprayed onto the spherical silica while stirring for 10 minutes, yielding silica 1 surface-treated with the internally reactive silane compound. The amount of silica 1 surface-treated with the internally reactive silane compound was 0.8% by mass.

[0284] <Production Example 2: Production of Silica 2 Surface-Treated with Internally Reactive Silane Compound> Silica 2 surface-treated with an internally reactive silane compound was produced by the same method as in Production Example 1, except that the amount of the internally reactive silane compound ("X-12-1333A" manufactured by Shin-Etsu Chemical Co., Ltd.) was changed to 0.4 parts by mass. The amount of the internally reactive silane compound surface-treated on silica 2 was 0.4% by mass.

[0285] <Production Example 3: Production of Silica 3 Surface-Treated with Internally Reactive Silane Compound> Silica 3 surface-treated with an internally reactive silane compound was produced in the same manner as in Production Example 1, except that the amount of the internally reactive silane compound ("X-12-1333A" manufactured by Shin-Etsu Chemical Co., Ltd.) was changed to 1.4 parts by mass. The amount of the internally reactive silane compound surface-treated on silica 3 was 1.4% by mass.

[0286] <Production Example 4. Production of Silica 4 Surface-Treated with Internally Reactive Silane Compound> Spherical silica (average particle size 0.5 μm, specific surface area 5.8 m 2100 parts by mass of silica (1000 ppm / g, Admatechs "SO-C2") was placed in a Henschel-type mixer. While spraying 0.4 parts by mass of an internally reactive silane compound (Shin-Etsu Chemical Co., Ltd. "X-12-1333A"), the spherical silica was stirred for 10 minutes to surface-treat the spherical silica with the internally reactive silane compound. Subsequently, while spraying 0.3 parts by mass of an amine-based alkoxysilane compound (Shin-Etsu Chemical Co., Ltd. "KBM-573"), the spherical silica was stirred for 10 minutes to further surface-treat the spherical silica with the amine-based alkoxysilane compound. Thus, silica 4 was obtained, which was surface-treated with the internally reactive silane compound and the amine-based alkoxysilane compound in that order. The amount of silica 4 surface-treated with the internally reactive silane compound was 0.4% by mass, and the amount of silica 4 surface-treated with the amine-based alkoxysilane compound was 0.3% by mass.

[0287] <Production Example 5: Production of Silica 5 Surface-Treated with Internally Reactive Silane Compound> Spherical silica (average particle size 0.5 μm, specific surface area 5.8 m 2 100 parts by mass of silica (100% ethanol / g, Admatechs "SO-C2") was placed in a Henschel-type mixer. While spraying 0.3 parts by mass of an amine-based alkoxysilane compound (Shin-Etsu Chemical Co., Ltd. "KBM-573"), the spherical silica was stirred for 10 minutes to surface-treat the spherical silica with the amine-based alkoxysilane compound. Subsequently, while spraying 0.4 parts by mass of an internally reactive silane compound (Shin-Etsu Chemical Co., Ltd. "X-12-1333A"), the spherical silica was stirred for 10 minutes to further surface-treat the spherical silica with the internally reactive silane compound. Thus, silica 5 was obtained, which was surface-treated with the amine-based alkoxysilane compound and the internally reactive silane compound in that order. The amount of silica 5 surface-treated with the amine-based alkoxysilane compound was 0.3% by mass, and the amount of silica 5 surface-treated with the internally reactive silane compound was 0.4% by mass.

[0288] <Production Example 6: Production of hollow silica 6 surface-treated with internally reactive silane compound> Hollow silica 6 surface-treated with an internally reactive silane compound was produced in the same manner as in Production Example 1, except that 100 parts by mass of hollow silica (average particle size 0.5 μm, porosity 30%-50%, Ube Exsymo "Hipressica FH") was used instead of 100 parts by mass of spherical silica (Admatechs "SO-C2"), and the amount of internally reactive silane compound (Shin-Etsu Chemical Co., Ltd. "X-12-1333A") was changed to 1.2 parts by mass. The amount of surface treatment of hollow silica 6 with the internally reactive silane compound was 1.2% by mass.

[0289] <Production Example 7: Production of Silica 7 Surface-Treated with Internally Reactive Silane Compound> Instead of 100 parts by mass of spherical silica ("SO-C2" manufactured by Admatechs Co., Ltd.), spherical silica (average particle size 0.3 μm, specific surface area 5.8 m) was used. 2 Silica 7 surface-treated with an internally reactive silane compound was produced by the same method as in Production Example 1, except that 100 parts by mass of an internally reactive silane compound (X-12-1333A manufactured by Shin-Etsu Chemical Co., Ltd.) was used, and the amount of the internally reactive silane compound was changed to 2.2 parts by mass. The amount of the internally reactive silane compound used for surface treatment of silica 7 was 2.2% by mass.

[0290] <Production Example 8: Production of Silica 8 Surface-Treated with an Arbitrary Silane Compound> Silica 8 surface-treated with an amine-based alkoxysilane compound was produced by the same method as in Production Example 1, except that 0.8 parts by mass of an amine-based alkoxysilane compound ("KBM-573" manufactured by Shin-Etsu Chemical Co., Ltd.) was used instead of 0.8 parts by mass of an internally reactive silane compound ("X-12-1333A" manufactured by Shin-Etsu Chemical Co., Ltd.). The amount of the amine-based alkoxysilane compound surface-treated on silica 8 was 0.8% by mass.

[0291] <Production Example 9: Production of Silica 9 Surface-Treated with an Arbitrary Silane Compound> Silica 9 surface-treated with a methacrylic alkoxysilane compound was produced in the same manner as in Production Example 1, except that 0.8 parts by mass of a methacrylic alkoxysilane compound (3-methacryloxypropyltrimethoxysilane, "KBM-503" manufactured by Shin-Etsu Chemical Co., Ltd.) was used instead of 0.8 parts by mass of the internally reactive silane compound ("X-12-1333A" manufactured by Shin-Etsu Chemical Co., Ltd.). The amount of the methacrylic alkoxysilane compound surface-treated on silica 9 was 0.8% by mass.

[0292] <Production Example 10: Production of Silica 10 Surface-Treated with an Arbitrary Silane Compound> Instead of 100 parts by mass of spherical silica ("SO-C2" manufactured by Admatechs Co., Ltd.), spherical silica (average particle size 0.3 μm, specific surface area 5.8 m) was used. 2 Silica 10 surface-treated with an amine-based alkoxysilane compound was produced by the same method as in Production Example 1, except that 100 parts by mass of an amine-based alkoxysilane compound (manufactured by Shin-Etsu Chemical Co., Ltd., "KBM-573") was used instead of 0.8 parts by mass of an internally reactive silane compound (manufactured by Shin-Etsu Chemical Co., Ltd., "X-12-1333A") was used. The amount of silica 10 surface-treated with the amine-based alkoxysilane compound was 2.0% by mass.

[0293] <Examples 1 to 7 and Comparative Examples 1 to 3. Production of Resin Varnish> Each component was weighed out and mixed in the amount (parts by mass) shown in the table below, and then 10 parts by mass of methyl ethyl ketone and 10 parts by mass of cyclohexanone were added and uniformly dispersed using a high-speed rotating mixer to obtain a resin varnish. Details of each component shown in the table below are as follows.

[0294] (A) Internally reactive silane compounds: X-12-1333A: Internally reactive silane compound (Shin-Etsu Chemical Co., Ltd., molecular weight 304)

[0295] (B) Radical reactive resin: Maleimide A: a solution containing 70% by mass of non-volatile components, the maleimide resin synthesized in Synthesis Example 1 MIR-3000-70T: 70% non-volatile component in toluene solution, maleimide resin, manufactured by Nippon Kayaku Co., Ltd. SLK-6895-T90: 90% non-volatile matter in toluene solution, maleimide resin, manufactured by Shin-Etsu Chemical Co., Ltd. BMI-2300: Maleimide resin, manufactured by Daiwa Chemical Industry Co., Ltd. OPE-2St: solution of 65% non-volatile components, styryl resin (vinylbenzyl-modified polyphenylene ether), manufactured by Mitsubishi Gas Chemical Co., Ltd. NE-V-1100-70T: Allyl resin, toluene solution with 70% non-volatile components, manufactured by DIC Styryl resin B: a solution containing 50% by mass of nonvolatile components, the styryl resin synthesized in Synthesis Example 2 A-DOG: (meth)acrylic resin (multifunctional acrylate; dioxane glycol diacrylate), manufactured by Shin-Nakamura Chemical Co., Ltd.

[0296] (C-1) Inorganic filler surface-treated with an internally reactive silane compound: Silica 1: Silica produced in Production Example 1. Surface treatment amount with internal reactive silane compound: 0.8 mass %. Silica 2: Silica produced in Production Example 2. The amount of surface treatment with the internal reactive silane compound was 0.4% by mass. Silica 3: Silica produced in Production Example 3. The amount of surface treatment with the internal reactive silane compound was 1.4 mass %. Silica 4: Silica produced in Production Example 4. Surface treatment amount with internal reactive silane compound: 0.4 mass %, surface treatment amount with amine-based alkoxysilane compound: 0.3 mass %. Silica 5: Silica produced in Production Example 5. Surface treatment amount with amine-based alkoxysilane compound: 0.3 mass %, surface treatment amount with internally reactive silane compound: 0.4 mass %. Silica 6: Hollow silica produced in Production Example 6. The amount of surface treatment with the internal reactive silane compound was 1.2% by mass. Silica 7: Silica produced in Production Example 7. The amount of surface treatment with the internal reactive silane compound was 2.2 mass %.

[0297] (C-2) Inorganic fillers that have not been surface-treated with internally reactive silane compounds: Silica 8: Silica produced in Production Example 8. Amount of surface treatment with amine-based alkoxysilane compound: 0.8 mass %. Silica 9: Silica produced in Production Example 9. Amount of surface treatment with methacrylic alkoxysilane compound: 0.8 mass %. Silica 10: Silica produced in Production Example 10. Amount of surface treatment with an amine-based alkoxysilane compound: 2.0 mass%.

[0298] (D) Thermosetting resin: ZX-1059: Epoxy resin (1:1 mixture of bisphenol A epoxy resin and bisphenol F epoxy resin), epoxy equivalent 169g / eq., manufactured by Nippon Steel Chemical & Material Co., Ltd. LA-3018-50P: Phenolic resin, 1-methoxy-2-propanol solution containing 50% non-volatile components by mass, active group equivalent weight 151 g / eq., manufactured by DIC Corporation. ALP-d: Benzoxazine resin, solution with 50% non-volatile content by mass, active group equivalent weight 257g / eq., manufactured by Shikoku Chemicals Corporation. HPC-8150-62T: Activated ester resin with a naphthalene structure, solution with 62% non-volatile content, active group equivalent weight of approximately 229 g / eq., manufactured by DIC Corporation.

[0299] (E) Polymer resin: Elastomer C: Resin synthesized in Synthesis Example 3. Non-volatile components: 50% by mass. PX-3-RP-61: Polystyrene resin, manufactured by Nippon Shokubai Co., Ltd. YX7553BH30: Phenoxy resin, manufactured by Mitsubishi Chemical Corporation. Non-volatile content: 30% by mass. EXL2655: Core-shell graft copolymer rubber particles, manufactured by The Dow Chemical Company. Polyimide D: Resin synthesized in Synthesis Example 4. Non-volatile content: 20% by mass.

[0300] (F) Thermal polymerization initiator: Perhexyl D: Peroxide radical polymerization initiator, di-tert-hexyl peroxide, manufactured by NOF Corporation.

[0301] (G) Curing accelerator: 1B2PZ: Imidazole curing accelerator, manufactured by Shikoku Chemicals Corporation

[0302] <Manufacturing of resin sheets> A polyethylene terephthalate film ("AL5" manufactured by Lintec Corporation, thickness 38 μm) with a release layer was prepared as a support. The resin varnishes obtained in the Examples and Comparative Examples were uniformly applied onto the release layer of this support so that the thickness of the thermosetting resin composition layer after drying would be 40 μm. The applied resin varnish was then dried at 80°C to 100°C (average 90°C) for 2 minutes to obtain a resin sheet including the support and the thermosetting resin composition layer.

[0303] <Measurement of minimum melt viscosity> A portion of the thermosetting resin composition layer was peeled off from the resin sheet to obtain a sample resin composition. The melt viscosity of the sample resin composition was measured using a dynamic viscoelasticity measuring device (Rheosol-G3000, manufactured by UBM). Specifically, 1 g of the sample resin composition was heated from an initial temperature of 60°C to 200°C at a heating rate of 5°C / min using parallel plates with a diameter of 18 mm. The dynamic viscoelasticity was measured under the following conditions: measurement interval temperature 2.5°C, frequency 1 Hz, and strain 5°C, and the minimum melt viscosity (poise) was calculated.

[0304] <Measurement of dielectric loss tangent, strength at break, and elongation at break> (1) Preparation of hardened product: The resin sheets obtained in the examples and comparative examples were heated in an oven at 190°C for 90 minutes to cure the thermosetting resin composition layer. The support was peeled off from the resin sheet taken out of the oven to obtain a cured product of the thermosetting resin composition layer.

[0305] (2) Measurement of dielectric loss tangent: The cured product was cut into a piece of 80 mm long and 2 mm wide to obtain a test piece. The dielectric loss tangent (Df value) of the test piece was measured by the cavity resonance perturbation method using a measuring device (Agilent Technologies "HP8362B") at a measurement frequency of 5.8 GHz and a measurement temperature of 23°C. Measurements were performed on two test pieces, and the average was calculated.

[0306] (3) Measurement of breaking strength and breaking elongation: The cured product was subjected to tensile strength measurement using a tensile tester ("RTC-1250A" manufactured by Orientec Co., Ltd.), and the strength at break and elongation at break at 23°C were measured. The measurement was carried out in accordance with JIS K7127. The measurement was carried out five times, and the average value of the top three points was calculated.

[0307] <Metal foil adhesion evaluation method> The metal foil adhesion was evaluated by measuring the copper foil peel strength according to the following procedure.

[0308] (1) Copper foil surface preparation: The shiny side of an electrolytic copper foil (Mitsui Mining & Smelting Co., Ltd., "3EC-III," 35 μm thick) was etched to a depth of 1 μm with a microetching agent (Mec Co., Ltd., "CZ8101") to roughen the copper surface, followed by a rust-proofing treatment (CL8300). The copper foil whose surface had been etched with the microetching agent in this manner is hereinafter sometimes referred to as "CZ copper foil." Furthermore, this copper foil was heat-treated in an oven at 130°C for 30 minutes to obtain copper foil I having a roughened treated surface.

[0309] (2) Preparation of inner layer board: A glass cloth-based epoxy resin double-sided copper-clad laminate (copper foil thickness 18 μm, substrate thickness 0.4 mm, Panasonic "R1515A") with copper foil on the surface and inner layer circuitry was prepared. Both sides of this glass cloth-based epoxy resin double-sided copper-clad laminate were etched to a depth of 1 μm using a microetching agent (MEC "CZ8101") to roughen the copper foil surface. This resulted in an inner layer substrate with a treated CZ copper foil on its surface.

[0310] (3) Lamination of thermosetting resin composition layer: The resin sheets prepared in the Examples and Comparative Examples were laminated on both sides of an inner layer substrate. This lamination was performed using a batch-type vacuum pressure laminator (Nikko Materials Co., Ltd., two-stage build-up laminator "CVP700") so that the thermosetting resin composition layer was in contact with the inner layer substrate. The lamination was performed by reducing the pressure for 30 seconds to 13 hPa or less, followed by pressure bonding at 120°C and a pressure of 0.74 MPa for 30 seconds. The laminated resin sheets were then heat-pressed at 100°C and a pressure of 0.5 MPa for 60 seconds to produce evaluation substrate A. The support was then peeled off to expose the thermosetting resin composition layer.

[0311] (4) Lamination of copper foil and curing of thermosetting resin composition layer: The treated surface of copper foil I was laminated onto the exposed thermosetting resin composition layer under the same conditions as in "(3) Lamination of thermosetting resin composition layer" above. The thermosetting resin composition layer was then cured at 200°C for 90 minutes to form an insulating layer containing a cured product of the thermosetting resin composition. Through these operations, evaluation substrate C was obtained, in which CZ copper foil was laminated on both sides of the insulating layer. This evaluation substrate C had a layer structure of copper foil I / insulating layer / inner layer substrate / insulating layer / copper foil I.

[0312] (5) Copper foil peel strength measurement: Evaluation board C was cut into small pieces measuring 150 mm x 30 mm. A cutter was used to cut a small piece of copper foil I, enclosing a rectangular area 10 mm wide and 100 mm long. One end of this rectangular area was peeled off and gripped with the gripper of a tensile tester (TSE Autocom Universal Tester AC-50C-SL). The copper foil was pulled vertically at a rate of 50 mm / min at room temperature (25°C), and the load [kgf / cm] required to peel off 35 mm was measured as the copper foil peel strength. Higher copper foil peel strength indicates better metal foil adhesion. Measurements were performed in accordance with Japanese Industrial Standard JIS C6481.

[0313] <Evaluation of unevenness after lamination> The above-described evaluation substrate A (evaluation substrate A before lamination with copper foil I) was heated at 200°C for 90 minutes to thermally cure the thermosetting resin composition layer, yielding a cured product. The cured product thus obtained was visually inspected for unevenness. Specifically, the unevenness was formed as depressions in the resin portion (here, the portion other than the inorganic filler), and the unevenness was evaluated based on the depressions in the resin portion. An inner layer substrate in which no depressions in the resin portion were observed over the entire substrate was rated as "excellent," one in which depressions in the resin portion were observed at the edges of the substrate but not in the center of the substrate was rated as "good," and one in which depressions in the resin portion were observed in the center of the substrate was rated as "poor."

[0314] <Result> The results of the examples and comparative examples are shown in the table below.

[0315] [Table 1]

[0316] [Table 2]

Claims

1. A thermosetting resin composition comprising (A) a silane compound having intramolecular cyclization reactivity and (B) a radical-reactive resin.

2. 2. The thermosetting resin composition according to claim 1, wherein the amount of component (A) is 0.1% by mass or more and 2.0% by mass or less, based on 100% by mass of the nonvolatile components of the thermosetting resin composition.

3. 2. The thermosetting resin composition according to claim 1, wherein the component (B) comprises at least one selected from the group consisting of a maleimide resin, a (meth)acrylic resin, a styryl resin, and an allyl resin.

4. The thermosetting resin composition according to claim 1 , wherein component (B) comprises a maleimide resin.

5. The thermosetting resin composition according to claim 1, further comprising (C) an inorganic filler.

6. 6. The thermosetting resin composition according to claim 5, wherein the component (C) comprises (C-1) an inorganic filler that has been surface-treated with the component (A).

7. 7. The thermosetting resin composition according to claim 6, wherein the amount of the surface treatment of the component (C-1) with the component (A) is 0.1% by mass or more and 3.0% by mass or less.

8. 6. The thermosetting resin composition according to claim 5, wherein the amount of component (C) is 50% by mass or more based on 100% by mass of the nonvolatile components of the thermosetting resin composition.

9. The thermosetting resin composition according to claim 1, further comprising (D) a thermosetting resin.

10. 2. The thermosetting resin composition of claim 1, having a minimum melt viscosity of 4000 poise or less.

11. The thermosetting resin composition according to claim 1, which is used to form an insulating layer of a circuit board.

12. A method for producing the thermosetting resin composition of claim 1, comprising: A method for producing a thermosetting resin composition, comprising the step of mixing (A) a silane compound having intramolecular cyclization reactivity and (B) a radical-reactive resin.

13. A method for producing the thermosetting resin composition according to claim 6, comprising: (A) a silane compound having intramolecular cyclization reactivity and (C') an inorganic filler before surface treatment are mixed to obtain (C-1) an inorganic filler surface-treated with component (A); a step of mixing the component (C-1) with the radical reactive resin (B); A method for producing a thermosetting resin composition, comprising:

14. A support and a thermosetting resin composition layer provided on the support, A resin sheet, wherein the thermosetting resin composition layer comprises the thermosetting resin composition according to any one of claims 1 to 11.

15. A cured product of the thermosetting resin composition according to any one of claims 1 to 11.

16. A circuit board comprising a cured product of the thermosetting resin composition according to any one of claims 1 to 11.

17. A semiconductor device comprising the circuit board according to claim 16.

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