Resin sheet with metal foil

Abstract

To provide a resin sheet with a metal foil capable of giving a cured product having a high glass transition temperature and excellent mechanical characteristics.SOLUTION: A resin sheet with a metal foil includes a metal foil, a resin composition layer, and a protective film in this order. The resin composition layer contains (A) a polyimide resin, (B) a phenoxy resin, and (C) an inorganic filler. When the content of the component (A) is a1 based on 100 mass% of a resin component in the resin composition layer and the content of the component (B) is b1 based on 100 mass% of the resin component in the resin composition layer, a1 / b1 is 0.05 or more and 50 or less.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a resin sheet with a metal foil. Further, the present invention relates to a circuit board manufactured using the resin sheet with a metal foil, a semiconductor device including the circuit board, and a method for manufacturing the circuit board.

Background Art

[0002] Conventionally, polyimide resins having excellent heat resistance and insulation properties have been used for insulating layers of circuit boards and the like (see, for example, Patent Documents 1 and 2).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] In recent years, as a method for forming a conductor layer on an insulating layer, a resin sheet with a metal foil is used. In this case, a resin sheet with a metal foil having a metal foil, a resin composition layer, and a protective film in this order is prepared, and the protective film is peeled off. Then, vacuum press treatment (vacuum hot press treatment) of the inner layer substrate and the resin sheet with a metal foil is performed so that the resin composition layer and the inner layer substrate are joined. Since the resin composition layer thermosets during the vacuum press treatment, an insulating layer including a cured product of the resin composition layer and a conductor layer corresponding to the metal foil can be formed on the inner layer substrate.

[0005] However, in the above method, during the vacuum press treatment, the resin composition layer is sandwiched between the inner layer substrate and the metal foil. Therefore, when the resin composition layer is thermally cured, the movement between molecules in the curing reaction of the resin component contained in the resin composition layer is suppressed. For this reason, the curing of the resin composition layer does not proceed sufficiently, the glass transition temperature of the insulating layer is low, and the mechanical properties of the cured product may be inferior.

[0006] Thus, the inventors have found a new problem that when forming an insulating layer by vacuum press treatment using a resin sheet with a metal foil, the glass transition temperature of the cured product of the resin composition layer is low and the mechanical properties are inferior.

[0007] The present invention was devised in view of the above problems, and an object thereof is to provide a resin sheet with a metal foil capable of obtaining a cured product having a high glass transition temperature and excellent mechanical properties; a circuit board manufactured using the resin sheet with a metal foil; a semiconductor device including the circuit board; and a method for manufacturing a circuit board.

Means for Solving the Problems

[0008] As a result of intensive studies by the inventors, a resin sheet with a metal foil including a metal foil, a resin composition layer, and a protective film in this order, wherein (A) a polyimide resin and (B) a phenoxy resin are contained in the resin composition layer so that each content is within a predetermined range, and further (C) an inorganic filler is contained, and it has been found that a cured product having a high glass transition temperature and excellent mechanical strength can be obtained, thus completing the present invention.

[0009] That is, the present invention includes the following content. [1] A resin sheet with a metal foil including a metal foil, a resin composition layer, and a protective film in this order, The resin composition layer contains (A) a polyimide resin, (B) a phenoxy resin, and (C) an inorganic filler, A metal foil - attached resin sheet, wherein when the content of component (A) is a1 and the content of component (B) is b1, with respect to 100% by mass of the resin component in the resin composition layer, a1 / b1 is 0.05 or more and 50 or less. [2] The metal foil - attached resin sheet according to [1], wherein component (A) has an ester bond. [3] The metal foil - attached resin sheet according to [1] or [2], further comprising a (G) flame retardant. [4] The metal foil - attached resin sheet according to any one of [1] to [3], wherein when the weight - average molecular weight of component (A) is a2 and the weight - average molecular weight of component (B) is b2, a2 / b2 is 0.01 or more and 10 or less. [5] The metal foil - attached resin sheet according to any one of [1] to [4], further comprising a (D) thermosetting resin. [6] The metal foil - attached resin sheet according to any one of [1] to [5], which is used for forming an insulating layer and a conductor layer by vacuum press treatment. [7] The metal foil - attached resin sheet according to any one of [1] to [6], wherein the metal foil is a copper foil. [8] A circuit board comprising an insulating layer formed by a cured product of the resin composition layer of the metal foil - attached resin sheet according to any one of [1] to [7], and a conductor layer formed from the metal foil of the metal foil - attached resin sheet according to any one of [1] to [7]. [9] A semiconductor device comprising the circuit board according to [8].

[10] A method for manufacturing a circuit board, comprising: (I) a step of laminating a resin composition layer in the metal foil - attached resin sheet according to any one of [1] to [7] on an inner - layer substrate by vacuum press treatment; and (II) a step of thermally curing the resin composition layer to form an insulating layer. [Effects of the Invention]

[0010] According to the present invention, there can be provided a metal foil - attached resin sheet capable of obtaining a cured product having a high glass transition temperature and excellent mechanical properties; a circuit board manufactured using the metal foil - attached resin sheet, a semiconductor device including the circuit board, and a method for manufacturing a circuit board.

Mode for Carrying Out the Invention

[0011] Hereinafter, the present invention will be described in detail with reference to embodiments and exemplifications. However, the present invention is not limited to the embodiments and exemplifications listed below, and can be arbitrarily modified and implemented without departing from the scope of the claims of the present invention and its equivalent scope.

[0012] [Resin Sheet with Metal Foil] The resin sheet with metal foil of the present invention includes a metal foil, a resin composition layer, and a protective film in this order. Usually, the metal foil and the resin composition layer are in direct contact with each other, and no other layer is provided between the metal foil and the resin composition layer. Also, usually, the resin composition layer and the protective film are in direct contact with each other, and no other layer is provided between the resin composition layer and the protective film. The resin composition layer contains (A) a polyimide resin, (B) a phenoxy resin, and (C) an inorganic filler. When the content of component (A) is a1 and the content of component (B) is b1 when the resin component excluding component (C) in the resin composition layer is 100% by mass, a1 / b1 is 0.05 or more and 50 or less. Such a resin sheet with metal foil can obtain a cured product having a high glass transition temperature and excellent mechanical properties. Also, the resin sheet with metal foil usually has excellent film flexibility, can obtain a cured product having a low dielectric constant and a low dielectric tangent, and has excellent flame retardancy. Here, the film flexibility refers to the property that the flexibility of the resin composition layer is high and cracks and chips in the resin composition layer can be suppressed.

[0013] [Metal Foil] The resin sheet with metal foil of the present invention has a metal foil. The conductor layer of the circuit board may be formed from the metal foil. At this time, the conductor layer may be formed by the entire metal foil or a part of the metal foil.

[0014] Examples of the metal foil include, for example, copper foil, aluminum foil, etc., and copper foil is preferred. As the copper foil, a foil made of single metal of copper may be used, or a foil made of an alloy of copper and other metals (for example, tin, chromium, silver, magnesium, nickel, zirconium, silicon, titanium, etc.) may be used.

[0015] The metal foil may have a single-layer structure or a multi-layer structure in which two or more single metal layers or alloy layers made of different types of metals or alloys are laminated. Examples of the multi-layer structure metal foil include, for example, a metal foil including a carrier metal foil and an ultra-thin metal foil joined to the carrier metal foil. Such a multi-layer structure metal foil may include a release layer between the carrier metal foil and the ultra-thin metal foil to make the ultra-thin metal foil peelable from the carrier metal foil. The release layer is not particularly limited as long as the ultra-thin metal foil can be peeled from the carrier metal foil, and examples include an alloy layer of an element selected from the group consisting of Cr, Ni, Co, Fe, Mo, Ti, W, and P; an organic film, etc. When using a multi-layer structure metal foil, the resin composition layer is provided on the ultra-thin metal foil.

[0016] From the viewpoint of significantly obtaining the effects of the present invention, the thickness of the metal foil is preferably 1 μm or more, more preferably 1.5 μm or more, and still more preferably 2 μm or more. The upper limit is not particularly limited, but is preferably 35 μm or less, more preferably 25 μm or less, and still more preferably 15 μm or less. When the metal foil has a multi-layer structure, it is preferable that the total thickness of the metal foil is within such a range, and among them, the thickness of the ultra-thin metal foil may be, for example, in the range of 0.1 μm or more and 10 μm or less.

[0017] The arithmetic mean roughness (Ra) of the surface in contact with the resin composition layer of the metal foil is preferably 300 nm or more, preferably 350 nm or more, more preferably 400 nm or more, and still more preferably 500 nm or more from the viewpoint of improving the adhesion to the resin composition layer. The upper limit is not particularly limited, but is preferably 1000 nm or less, more preferably 900 nm or less, and still more preferably 800 nm or less. The arithmetic mean roughness (Ra) is a value measured in accordance with ISO 25178 and can be measured using a non-contact surface roughness meter. Examples of the non-contact surface roughness meter include "WYKO NT3300" manufactured by Veeco Instruments Inc.

[0018] Commercially available products may be used for the metal foil. Examples of commercially available products of the metal foil include "Microsin MT18Ex", "Microsin MT18FL", "3EC-III", "3EC-M3-VLP", "3EC-M2S-VLP" manufactured by Mitsui Mining & Smelting Co., Ltd., "JDLC", "JTCSLC", "HA-V2", "HA", "HG" manufactured by JX Metals, "CF-TX4-SV", "V9", "HD", "FLEQ HD", "FUTF", "RCF-T4X", "RCF-T5B", etc. manufactured by Fukuda Metal Foil & Powder Co., Ltd.

[0019] As a method for manufacturing the metal foil, for example, it can be manufactured by a known method such as an electrolytic method or a rolling method.

[0020] <Resin composition layer> The resin sheet with metal foil has a resin composition layer. An insulating layer can be formed by thermally curing the resin composition layer. Usually, the insulating layer contains a cured product of the resin composition layer and preferably contains only the cured product of the resin composition layer.

[0021] The resin composition layer contains (A) a polyimide resin, (B) a phenoxy resin, and (C) an inorganic filler. Further, the resin composition layer may contain (D) a thermosetting resin, (E) a thermoplastic resin (excluding those corresponding to the (A) component and the (B) component), (F) a flame retardant, (G) a curing accelerator, (H) other additives, and (I) a solvent as required.

[0022] In the present invention, unless otherwise specified, the content of each component in the resin composition layer is a value when the non-volatile components in the resin composition layer are 100% by mass. In the present invention, the non-volatile components mean all the components excluding the solvent in the resin composition layer. In the present invention, the resin component in the resin composition layer represents the component excluding (C) the inorganic filler among the non-volatile components of the resin composition layer.

[0023] -(A) Polyimide resin- The resin composition layer contains a polyimide resin as the component (A). By including the component (A) in the resin composition layer, it becomes possible to obtain a cured product with a high glass transition temperature. The component (A) may be used alone or in combination of two or more.

[0024] As the (A) polyimide resin, a resin having an imide bond in the repeating unit can be used, and from the viewpoint of increasing the glass transition temperature of the cured product, it preferably has an ester bond. The (A) polyimide resin generally includes those obtained by an imidization reaction of a diamine compound and an acid anhydride.

[0025] The diamine compound for preparing the (A) polyimide resin is not particularly limited, and examples thereof include an aliphatic diamine compound and an aromatic diamine compound. Among them, as the diamine compound, an aromatic diamine compound is preferable. From the viewpoint of increasing the glass transition temperature of the cured product, the diamine compound preferably has an ester bond, and an aromatic diamine compound having an ester bond is more preferable.

[0026] Examples of the aliphatic diamine compound include linear aliphatic diamine compounds such as 1,2-ethylenediamine, 1,2-diaminopropane, 1,3-diaminopropane, 1,4-diaminobutane, 1,6-hexamethylenediamine, 1,5-diaminopentane, 1,10-diaminodecane; branched aliphatic diamine compounds such as 1,2-diamino-2-methylpropane, 2,3-diamino-2,3-butane, and 2-methyl-1,5-diaminopentane; alicyclic diamine compounds such as 1,3-bis(aminomethyl)cyclohexane, 1,4-bis(aminomethyl)cyclohexane, 1,4-diaminocyclohexane, 4,4'-methylenebis(cyclohexylamine); dimer acid type diamine (hereinafter also referred to as "dimer diamine"), etc. Among them, the dimer acid type diamine is preferred.

[0027] The dimer acid type diamine means a diamine compound obtained by substituting two terminal carboxylic acid groups (-COOH) of dimer acid with an aminomethyl group (-CH2-NH2) or an amino group (-NH2). Dimer acid is a known compound obtained by dimerizing unsaturated fatty acids (preferably those having 11 to 22 carbon atoms, particularly preferably those having 18 carbon atoms), and its industrial manufacturing process is almost standardized in the industry. Dimer acid is mainly composed of dimer acid having 36 carbon atoms obtained by dimerizing unsaturated fatty acids having 18 carbon atoms such as oleic acid and linoleic acid, which are particularly inexpensive and easily available, and is easily available. In addition, dimer acid may contain an arbitrary amount of monomer acid, trimer acid, and other polymerized fatty acids depending on the manufacturing method, degree of purification, etc. Further, double bonds remain after the polymerization reaction of unsaturated fatty acids, but in this specification, hydrogenated products obtained by further hydrogenation reaction to reduce the degree of unsaturation are also included in dimer acid. Commercially available dimer acid type diamines are available, and examples include "PRIAMINE 1073", "PRIAMINE 1074", "PRIAMINE 1075" manufactured by Croda Japan; "Versamine 551", "Versamine 552" manufactured by Cognis Japan, etc.

[0028] Examples of the aromatic diamine compound include, for example, a phenylenediamine compound, a naphthalenediamine compound, a dianiline compound, etc., and a dianiline compound is preferred.

[0029] The phenylenediamine compound means a compound composed of a benzene ring having two amino groups, and further, the benzene ring herein may optionally have 1 to 3 substituents. Specific examples of the phenylenediamine compound include 1,4-phenylenediamine, 1,2-phenylenediamine, 1,3-phenylenediamine, 2,4-diaminotoluene, 2,6-diaminotoluene, 3,5-diaminobiphenyl, 2,4,5,6-tetrafluoro-1,3-phenylenediamine, etc.

[0030] The substituent is not particularly limited. For example, a halogen atom, -OH, -O-C 1-6 alkyl group, -N(C 1-10 alkyl group)2, C 1-20 alkyl group, C 2-30 alkenyl group, C 2-30 alkynyl group, C 6-10 aryl group, -NH2, -CN, -C(O)O-C 1-10 alkyl group, -COOH, -C(O)H, -NO2, etc. are mentioned. Here, the term "C p-q "(p and q are positive integers and satisfy p < q.) represents that the number of carbon atoms of the organic group described immediately after this term is p to q. For example, the expression "C 1-10 alkyl group" indicates an alkyl group having 1 to 10 carbon atoms. These substituents may be bonded to each other to form a ring, and the ring structure includes a spiro ring and a condensed ring.

[0031] The naphthalenediamine compound means a compound consisting of a naphthalene ring having two amino groups, and further, the naphthalene ring herein may optionally have 1 to 3 substituents. The substituents are the same as those that the phenylenediamine compound may have. Specific examples of the naphthalenediamine compound include 1,5-diaminonaphthalene, 1,8-diaminonaphthalene, 2,6-diaminonaphthalene, 2,3-diaminonaphthalene, and the like.

[0032] The dianiline compound means a compound containing two aniline structures in the molecule, and further, the two benzene rings in the two aniline structures may each optionally have 1 to 3 substituents. The substituents are the same as those that the phenylenediamine compound may have. The two aniline structures in the dianiline compound may be bonded directly and / or via one or two linker structures having 1 to 100 backbone atoms selected from carbon atoms, oxygen atoms, sulfur atoms, and nitrogen atoms. The dianiline compound includes those in which the two aniline structures are bonded by two bonds.

[0033] As the "linker structure" in the dianiline compound, specifically, -NHCO-, -CONH-, -OCO-, -COO-, -CH2-, -CH2CH2-, -CH2CH2CH2-, -CH2CH2CH2CH2-, -CH2CH2CH2CH2CH2-, -CH(CH3)-, -C(CH3)2-, -C(CF3)2-, -CH=CH-, -O-, -S-, -CO-, -SO2-, -NH-, -Ph-, -Ph-Ph-, -C(CH3)2-Ph-C(CH3)2-, -O-Ph-O-, -O-Ph-Ph-O-, -O-Ph-SO2-Ph-O-, -O-Ph-C(CH3)2-Ph-O-, -Ph-CO-O-Ph-, -C(CH3)2-Ph-C(CH3)2-, -O-Ph-C(CH3)2-Ph-C(CH3)2-Ph-O-, -Ph-O-Ph-C(CH3)2-Ph-C(CH3)2-Ph-O-Ph-, the groups represented by the following formulas (I) and (II), and groups composed of combinations thereof, etc. may be mentioned. In the present specification, "Ph" represents a 1,4-phenylene group, a 1,3-phenylene group, or a 1,2-phenylene group. Among them, as the linker structure, -COO-, -Ph-CO-O-Ph-, -C(CH3)2-Ph-C(CH3)2-, -O-Ph-C(CH3)2-Ph-C(CH3)2-Ph-O-, or -Ph-O-Ph-C(CH3)2-Ph-C(CH3)2-Ph-O-Ph- is preferable.

[0034] [Chemical formula]

[0035] In one embodiment, as the diamine compound, a diamine compound represented by the following formula (A-1) is preferable. [Chemical formula] (In formula (A-1), R 1 ~R 8 each independently represents a hydrogen atom, a halogen atom, a cyano group, a nitro group, -X 9 -R 9 , or -X 10 -R 10 represents, and R 1 ~R8 at least one of which is -X 10 -R 10 wherein X 9 is, independently of one another, a single bond, -NR 9’ -, -O-, -S-, -CO-, -SO2-, -NR 9’ CO-, -CONR 9’ -, -OCO-, or -COO-, and R 9 is, independently of one another, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted alkenyl group, and R 9’ is, independently of one another, a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted alkenyl group, and X 10 is, independently of one another, a single bond, -(substituted or unsubstituted alkylene group)-, -NH-, -O-, -S-, -CO-, -SO2-, -NHCO-, -CONH-, -OCO-, or -COO-, and R 10 is, independently of one another, a substituted or unsubstituted aryl group, or a substituted or unsubstituted heteroaryl group.)

[0036] The R 9 and R 9’ in formula (A-1) represent an alkyl group which is a linear, branched or cyclic monovalent aliphatic saturated hydrocarbon group. As the alkyl group, an alkyl group having 1 to 6 carbon atoms is preferable, and an alkyl group having 1 to 3 carbon atoms is more preferable. Examples of such an 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 neopentyl group, a cyclopentyl group, a cyclohexyl group and the like.

[0037] The R 9 and R 9’The alkenyl group represented by [the formula] refers to a linear, branched or cyclic monovalent unsaturated hydrocarbon group having at least one carbon-carbon double bond. As the alkenyl group, an alkenyl group having 2 to 6 carbon atoms is preferable, and an alkenyl group having 2 or 3 carbon atoms is more preferable. Examples of such alkenyl groups include a vinyl group, 1-propenyl group, 2-propenyl group, 2-methyl-1-propenyl group, 1-butenyl group, 2-butenyl group, 3-butenyl group, 3-methyl-2-butenyl group, 1-pentenyl group, 2-pentenyl group, 3-pentenyl group, 4-pentenyl group, 4-methyl-3-pentenyl group, 1-hexenyl group, 3-hexenyl group, 5-hexenyl group, 2-cyclohexenyl group and the like. The substituent of the alkenyl group in the "substituted or unsubstituted alkenyl group" is not particularly limited, and examples thereof include a halogen atom, a cyano group, an alkoxy group, an aryl group, a heteroaryl group, an amino group, a nitro group, a hydroxy group, a carboxy group, a sulfo group and the like. The number of substituents is preferably 1 to 3, and more preferably 1.

[0038] The substituent of the alkyl group in the "substituted or unsubstituted alkyl group" and the substituent of the alkenyl group in the "substituted or unsubstituted alkenyl group" are not particularly limited, and examples thereof include a halogen atom, a cyano group, an alkoxy group, an amino group, a nitro group, a hydroxy group, a carboxy group, a sulfo group and the like. The number of substituents is preferably 1 to 3, and more preferably 1.

[0039] The alkoxy group refers to a monovalent group (alkyl-O-) formed by bonding an alkyl group to an oxygen atom. As the alkoxy group, an alkoxy group having 1 to 6 carbon atoms is preferable, and an alkoxy group having 1 to 3 carbon atoms is more preferable. Examples of such alkoxy groups include a methoxy group, an ethoxy group, a propoxy group, an isopropoxy group, a butoxy group, an isobutoxy group, a sec-butoxy group, a tert-butoxy group, a pentyloxy group and the like.

[0040] X in formula (A-1) 10The alkylene group represented by [it] refers to a linear, branched or cyclic divalent aliphatic saturated hydrocarbon group, preferably an alkylene group having 1 to 6 carbon atoms, more preferably an alkylene group having 1 to 3 carbon atoms. Examples of the alkylene group include, for example, -CH2-, -CH2-CH2-, -CH(CH3)-, -CH2-CH2-CH2-, -CH2-CH(CH3)-, -CH(CH3)-CH2-, -C(CH3)2-, -CH2-CH2-CH2-CH2-, -CH2-CH2-CH(CH3)-, -CH2-CH(CH3)-CH2-, -CH(CH3)-CH2-CH2-, -CH2-C(CH3)2-, -C(CH3)2-CH2- and the like. The substituent of the alkylene group in the "substituted or unsubstituted alkylene group" is not particularly limited, and examples thereof include a halogen atom, a cyano group, an alkoxy group, an aryl group, a heteroaryl group, an amino group, a nitro group, a hydroxy group, a carboxy group, a sulfo group and the like. The number of substituents is preferably 1 to 3, more preferably 1.

[0041] R in formula (A-1) 10 The aryl group represented by [it] is preferably an aryl group having 6 to 14 carbon atoms, more preferably an aryl group having 6 to 10 carbon atoms. Examples of such an aryl group include, for example, a phenyl group, a 1-naphthyl group, a 2-naphthyl group and the like, and preferably a phenyl group. The substituent of the aryl group in the "substituted or unsubstituted aryl group" is not particularly limited, and examples thereof include a halogen atom, a cyano group, an alkyl group, an alkoxy group, an aryl group, a heteroaryl group, an amino group, a nitro group, a hydroxy group, a carboxy group, a sulfo group and the like. The number of substituents is preferably 1 to 3, more preferably 1.

[0042] R in formula (A-1) 10The heteroaryl group represented by means an aromatic heterocyclic group having 1 to 4 heteroatoms selected from an oxygen atom, a nitrogen atom and a sulfur atom. The heteroaryl group is preferably a monocyclic, bicyclic or tricyclic (preferably monocyclic) aromatic heterocyclic group having 5 to 12 members (preferably 5 or 6 members). Examples of such heteroaryl groups include a furyl group, a thienyl group, a pyrrolyl group, an oxazolyl group, an isoxazolyl group, a thiazolyl group, an isothiazolyl group, an imidazolyl group, a pyrazolyl group, a 1,2,3-oxadiazolyl group, a 1,2,4-oxadiazolyl group, a 1,3,4-oxadiazolyl group, a furazanyl group, a 1,2,3-thiadiazolyl group, a 1,2,4-thiadiazolyl group, a 1,3,4-thiadiazolyl group, a 1,2,3-triazolyl group, a 1,2,4-triazolyl group, a tetrazolyl group, a pyridyl group, a pyridazinyl group, a pyrimidinyl group, a pyrazinyl group, a triazinyl group and the like. The substituents of the heteroaryl group in the "substituted or unsubstituted heteroaryl group" are the same as the substituents of the aryl group in the "substituted or unsubstituted aryl group".

[0043] R 1 ~R 8 each independently represents a hydrogen atom, a halogen atom, a cyano group, a nitro group, -X 9 -R 9 or -X 10 -R 10 R 1 ~R 8 are preferably each independently a hydrogen atom or -X 10 -R 10 is.

[0044] R 1 ~R 8 at least one of is -X 10 -R 10 Preferably, one or two of R 1 ~R 8 are -X 10 -R 10 More preferably, one or two of R 5 ~R 8 are -X 10 -R 10and more preferably, R 5 and R 7 wherein one or two of them are -X 10 -R 10 .

[0045] In one embodiment, preferably, one or two of R 1 ~R 8 are -X 10 -R 10 , and the others of R 1 ~R 8 are hydrogen atoms. More preferably, one or two of R 5 ~R 8 are -X 10 -R 10 , and the others of R 1 ~R 8 are hydrogen atoms. Even more preferably, one or two of R 5 and R 7 are -X 10 -R 10 , and the others of R 1 ~R 8 are hydrogen atoms.

[0046] X 9 each independently represents a single bond, -NR 9’ -, -O-, -S-, -CO-, -SO2-, -NR 9’ CO-, -CONR 9’ -, -OCO-, or -COO-. R 9 each independently represents a substituted or unsubstituted alkyl group, or a substituted or unsubstituted alkenyl group. X 9 is preferably a single bond.

[0047] R 9’ each independently represents a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted alkenyl group. R 9 is preferably a substituted or unsubstituted alkyl group.

[0048] X 10Each independently represents a single bond, -(substituted or unsubstituted alkylene group)-, -NH-, -O-, -S-, -CO-, -SO2-, -NHCO-, -CONH-, -OCO-, or -COO-. X 10 is preferably a single bond.

[0049] R 10 Each independently represents a substituted or unsubstituted aryl group, or a substituted or unsubstituted heteroaryl group. R 10 is preferably a substituted or unsubstituted aryl group.

[0050] In one embodiment, the diamine compound represented by formula (A-1) is preferably a compound represented by the following formula (A-2), and more preferably a compound represented by the following formula (A-3) (4-aminobenzoic acid 5-amino-1,1'-biphenyl-2-yl (also known as: (5-amino-2-biphenyl)-4-aminobenzoate, PHBAAB)).

Chemical formula

Chemical formula

[0051] In another embodiment, the diamine compound is specifically 4,4'-diamino-2,2'-ditrifuluoromethyl-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]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, 4,4'-(m-phenylenediisopropylidene)dianiline (Bisaniline-M), 4,4'-[1,4-phenylenebis[(1-methylethylidene)-4,1-phenyleneoxy]]bisbenzeneamine (BPPAN), etc. Preferably, they are 4,4'-(m-phenylenediisopropylidene)dianiline and 4,4'-[1,4-phenylenebis[(1-methylethylidene)-4,1-phenyleneoxy]]bisbenzeneamine.Incidentally, 4,4'-(m-phenylenediisopropylidene)dianiline (Bisaniline-M) is a compound represented by the following formula (I), and 4,4'-[1,4-phenylenebis[(1-methylethylidene)-4,1-phenyleneoxy]]bisbenzeneamine (BPPAN) is a compound represented by the following formula (II). [Chemical formula]

[0052] In one embodiment, the diamine compound for preparing the polyimide resin preferably contains 4,4'-(m-phenylenediisopropylidene)dianiline (the compound represented by the above formula (I)), more preferably contains a combination of 4,4'-(m-phenylenediisopropylidene)dianiline and a diamine compound represented by formula (A-1), even more preferably contains a combination of 4,4'-(m-phenylenediisopropylidene)dianiline and a diamine compound represented by formula (A-2), and even more preferably contains a combination of 4,4'-(m-phenylenediisopropylidene)dianiline and (5-amino-2-biphenyl)-4-aminobenzoate (the compound represented by the above formula (A-3)).

[0053] When the diamine compound for preparing the polyimide resin contains 4,4'-(m-phenylenediisopropylidene)dianiline, the content of the structure derived from 4,4'-(m-phenylenediisopropylidene)dianiline is preferably 10 mol% or more, more preferably 30 mol% or more, even more preferably 50 mol% or more, and even more preferably 60 mol% or more with respect to 100 mol% of the total structure derived from the diamine compound constituting the polyimide resin.

[0054] As for the diamine compound, a commercially available one may be used, or one synthesized by a known method may be used. For example, the diamine compound represented by the formula (A-1) can be synthesized by the synthesis method described in Patent No. 6240798 or a method analogous thereto. The diamine compound may be used alone or in combination of two or more.

[0055] The acid anhydride for preparing the polyimide resin is not particularly limited, but in a preferred embodiment, it is an aromatic tetracarboxylic dianhydride. Examples of the aromatic tetracarboxylic dianhydride include benzene tetracarboxylic dianhydride, naphthalene tetracarboxylic dianhydride, anthracene tetracarboxylic dianhydride, diphthalic dianhydride, etc., and preferably diphthalic dianhydride.

[0056] Benzene tetracarboxylic dianhydride means a dianhydride of benzene having four carboxy groups, and further, the benzene ring here may optionally have 1 to 3 substituents. Here, the substituents include a halogen atom, a cyano group, and -X 13 -R 13 (the same as the definition of the following formula (A-4)) are preferably selected. Specific examples of the benzene tetracarboxylic dianhydride include pyromellitic dianhydride, 1,2,3,4-benzene tetracarboxylic dianhydride, etc.

[0057] Naphthalene tetracarboxylic dianhydride means a dianhydride of naphthalene having four carboxy groups, and further, the naphthalene ring here may optionally have 1 to 3 substituents. Here, the substituents include a halogen atom, a cyano group, and -X 13 -R 13 (the same as the definition of the following formula (A-4)) are preferably selected. Specific examples of the naphthalene tetracarboxylic dianhydride include 1,4,5,8-naphthalene tetracarboxylic dianhydride, 2,3,6,7-naphthalene tetracarboxylic dianhydride, etc.

[0058] Anthracenetetracarboxylic dianhydride means the dianhydride of anthracene having four carboxy groups, and further, the anthracene ring herein may optionally have 1 to 3 substituents. Here, examples of the substituent include a halogen atom, a cyano group, and -X 13 -R 13 (the same as the definition of formula (A-4) below) are preferably selected. Specific examples of the anthracenetetracarboxylic dianhydride include 2,3,6,7-anthracenetetracarboxylic dianhydride and the like.

[0059] Phthalic dianhydride means a compound containing two phthalic anhydrides in the molecule, and further, the two benzene rings in the two phthalic anhydrides may each optionally have 1 to 3 substituents. Here, examples of the substituent include a halogen atom, a cyano group, and -X 13 -R 13 (the same as the definition of formula (A-4) below) are preferably selected. The two phthalic anhydrides in the phthalic dianhydride may be bonded directly or via a linker structure having 1 to 100 skeletal atoms selected from a carbon atom, an oxygen atom, a sulfur atom, and a nitrogen atom.

[0060] Examples of the phthalic dianhydride include the compound represented by formula (A-4). [Chemical formula] (In the formula, R 11 and R 12 each independently represent a halogen atom, a cyano group, a nitro group, or -X 13 -R 13 and X 13 each independently represent a single bond, -NR 13’ -, -O-, -S-, -CO-, -SO2-, -NR 13’ CO-, -CONR 13’ -, -OCO-, or -COO-, and R 13 each independently represent a substituted or unsubstituted alkyl group, or a substituted or unsubstituted alkenyl group, R13’ each independently represents a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted alkenyl group, Y represents a single bond or a linker structure having 1 to 100 backbone atoms selected from carbon atoms, oxygen atoms, sulfur atoms, and nitrogen atoms, n1 and m1 each independently represent an integer from 0 to 3. )

[0061] Y is preferably a linker structure having 1 to 100 backbone atoms selected from carbon atoms, oxygen atoms, sulfur atoms, and nitrogen atoms. n1 and m1 are preferably 0.

[0062] The "linker structure" in Y has 1 to 100 backbone atoms selected from carbon atoms, oxygen atoms, sulfur atoms, and nitrogen atoms. The "linker structure" is preferably -[A-Ph] a -A-[Ph-A] b - [wherein A each independently represents a single bond, -(substituted or unsubstituted alkylene group)-, -O-, -S-, -CO-, -SO2-, -CONH-, -NHCO-, -COO-, or -OCO-, and a and b each independently represent an integer from 0 to 2 (preferably 0 or 1). ] is a divalent group represented by

[0063] Specific examples of the "linker structure" in Y include -CH2-, -CH2CH2-, -CH2CH2CH2-, -CH2CH2CH2CH2-, -CH2CH2CH2CH2CH2-, -CH(CH3)-, -C(CH3)2-, -O-, -CO-, -SO2-, -Ph-, -O-Ph-O-, -O-Ph-SO2-Ph-O-, -O-Ph-C(CH3)2-Ph-O-, etc., and -O-Ph-C(CH3)2-Ph-O- is preferred.

[0064] Specific examples of the diphthalic anhydride include 3,3’,4,4’-benzophenone tetracarboxylic dianhydride, 3,3’,4,4’-diphenyl ether tetracarboxylic dianhydride, 3,3’,4,4’-diphenyl sulfone tetracarboxylic dianhydride, 3,3’,4,4’-biphenyl tetracarboxylic dianhydride, 2,2’,3,3’-biphenyl tetracarboxylic dianhydride, 2,3,3’,4’-biphenyl tetracarboxylic dianhydride, 2,3,3’,4’-benzophenone tetracarboxylic dianhydride, 2,3,3’,4’-diphenyl ether tetracarboxylic dianhydride, 2,3,3’,4’-diphenyl sulfone tetracarboxylic dianhydride, 2,2’-bis(3,4-dicarboxyphenoxyphenyl) sulfone dianhydride, 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, 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, 4,4’-(4,4’-isopropylidenediphenoxy) bisphthalic dianhydride (BPADA), and the like.

[0065] In one embodiment, the diphthalic acid compound represented by formula (A-4) is preferably a compound represented by the following formula (A-5), and more preferably a compound represented by the following formula (A-6) (4,4’-(4,4’-isopropylidenediphenoxy) bisphthalic dianhydride: BPADA). [Chemical formula] (In the formula, R 11 and R12 is, independently of each other, a halogen atom, a cyano group, a nitro group, or -X 13 -R 13 wherein n1 and m1 each independently represent an integer of 0 to 3, and the other symbols are the same as in formula (A-4).)

Chemical formula

[0066] As the aromatic tetracarboxylic dianhydride, commercially available ones may be used, or those synthesized by known methods or methods analogous thereto may be used. The aromatic tetracarboxylic dianhydride may be used alone or in combination of two or more.

[0067] In one embodiment, the acid anhydride for preparing the polyimide resin may contain other acid anhydrides in addition to the aromatic tetracarboxylic dianhydride.

[0068] Specific examples of the other acid anhydrides include aliphatic tetracarboxylic dianhydrides such as 1,2,3,4-cyclobutanetetracarboxylic dianhydride, cyclopentanetetracarboxylic dianhydride, cyclohexane-1,2,3,4-tetracarboxylic dianhydride, cyclohexane-1,2,4,5-tetracarboxylic dianhydride, 3,3’,4,4’-bicyclohexyltetracarboxylic dianhydride, carbonyl-4,4’-bis(cyclohexane-1,2-dicarboxylic acid) dianhydride, methylene-4,4’-bis(cyclohexane-1,2-dicarboxylic acid) dianhydride, 1,2-ethylene-4,4’-bis(cyclohexane-1,2-dicarboxylic acid) dianhydride, oxy-4,4’-bis(cyclohexane-1,2-dicarboxylic acid) dianhydride, thio-4,4’-bis(cyclohexane-1,2-dicarboxylic acid) dianhydride, sulfonyl-4,4’-bis(cyclohexane-1,2-dicarboxylic acid) dianhydride, and the like.

[0069] The content of the structure derived from the aromatic tetracarboxylic dianhydride in the entire structure derived from the acid anhydride constituting the polyimide resin is preferably 10 mol% or more, more preferably 30 mol% or more, still more preferably 50 mol% or more, even more preferably 70 mol% or more, even more preferably 90 mol% or more, and particularly preferably 100 mol%.

[0070] The polyimide resin preferably has a structural unit represented by the following general formula (A).

Chemical formula

[0071] R 51 each independently represents a single bond or a residue derived from a phthalic dianhydride, and is preferably a residue derived from a phthalic dianhydride. The residue derived from the phthalic dianhydride represented by R 51 refers to a divalent group obtained by removing two phthalic anhydrides from the phthalic dianhydride. The phthalic dianhydride is as described above.

[0072] R 51 The examples of the residue derived from the phthalic dianhydride represented by are the same as the examples of the "linker structure" represented by Y in the formula (A-4). The residue derived from the phthalic dianhydride represented by R 51 is preferably a divalent group obtained by removing two phthalic anhydrides from 4,4'-(4,4'-isopropylidenediphenoxy)bisphtalic dianhydride (the compound represented by the above formula (A-6)).

[0073] R 52 each independently represents a single bond or a residue derived from a diamine compound, and is preferably a residue derived from a diamine compound. R 52The residue derived from the diamine compound represented by refers to a divalent group obtained by removing two amino groups from the diamine compound. The diamine compound is as described above.

[0074] R 52 The residue derived from the diamine compound represented by is preferably a divalent group obtained by removing two amino groups from 4,4'-(m-phenylenediisopropylidene)dianiline (the compound represented by the above formula (I)), or a divalent group obtained by removing two amino groups from the diamine compound represented by the formula (A-1). More preferably, it is a divalent group obtained by removing two amino groups from 4,4'-(m-phenylenediisopropylidene)dianiline, or the diamine compound represented by the formula (A-2). Even more preferably, it is a divalent group obtained by removing two amino groups from 4,4'-(m-phenylenediisopropylidene)dianiline, or (5-amino-2-biphenyl)-4-aminobenzoate (the compound represented by the above formula (A-3)).

[0075] In one embodiment, the polyimide resin may be a copolymer having a plurality of different structural units represented by the formula (A). In such an embodiment, the polyimide resin preferably has a structural unit in which R 52 in the formula (A) is a divalent group obtained by removing two amino groups from 4,4'-(m-phenylenediisopropylidene)dianiline (the compound represented by the above formula (I)), and a structural unit in which R 52 in the formula (A) is a divalent group obtained by removing two amino groups from a diamine compound other than 4,4'-(m-phenylenediisopropylidene)dianiline. As the diamine compound other than 4,4'-(m-phenylenediisopropylidene)dianiline, the diamine compound represented by the formula (A-1) is preferred, the diamine compound represented by the formula (A-2) is more preferred, and (5-amino-2-biphenyl)-4-aminobenzoate (the compound represented by the above formula (A-3)) is even more preferred. In a more preferred embodiment, the polyimide resin has R 52is a divalent group obtained by removing two amino groups from 4,4'-(m-phenylenediisopropylidene)dianiline, and R in formula (A) 52 is a divalent group obtained by removing two amino groups from (5-amino-2-biphenyl)-4-aminobenzoate.

[0076] In one embodiment, the polyimide resin preferably contains a structural unit (hereinafter sometimes referred to as "structural unit A1") obtained by reacting 4,4'-(m-phenylenediisopropylidene)dianiline (the compound represented by the above formula (I)) with 4,4'-(4,4'-isopropylidenediphenoxy)bisphtalic dianhydride (BPADA: the compound represented by the above formula (A-6)). Further, in such an embodiment, it is more preferable that the polyimide resin contains, in addition to the structural unit A1, a structural unit obtained by reacting (5-amino-2-biphenyl)-4-aminobenzoate (the compound represented by the above formula (A-3)) with 4,4'-(4,4'-isopropylidenediphenoxy)bisphtalic dianhydride.

[0077] (A) The polyimide resin can be prepared by a conventionally known method. Examples of the known method include a method of heating and reacting a mixture of a diamine compound, an acid anhydride, and a solvent. The mixing amount of the diamine compound can be, for example, usually 0.5 to 1.5 molar equivalents, preferably 0.9 to 1.1 molar equivalents, relative to the acid anhydride.

[0078] (A) Solvents used in the preparation of polyimide resins include amide solvents such as N,N-dimethylacetamide, N,N-diethylacetamide, N,N-dimethylformamide, and N-methyl-2-pyrrolidone; ketone solvents such as acetone, methyl ethyl ketone (MEK), and cyclohexanone; ester solvents such as γ-butyrolactone; and hydrocarbon solvents such as cyclohexane and methylcyclohexane. In addition, for the preparation of polyimide resins, an imidization catalyst, an azeotropic dehydrating solvent, an acid catalyst, etc. may be used as necessary. Examples of imidization catalysts include tertiary amines such as triethylamine, triisopropylamine, triethylenediamine, N-methylpyrrolidine, N-ethylpyrrolidine, N,N-dimethyl-4-aminopyridine, and pyridine. Examples of azeotropic dehydrating solvents include toluene, xylene, and ethylcyclohexane. Examples of acid catalysts include acetic anhydride. The usage amounts of the imidization catalyst, azeotropic dehydrating solvent, acid catalyst, etc. can be appropriately set by those skilled in the art. The reaction temperature for the preparation of (A) polyimide resin is usually 100 to 250 °C.

[0079] (A) The weight average molecular weight of the component is preferably 3000 or more, more preferably 5000 or more, still more preferably 8000 or more, and preferably 200000 or less, more preferably 100000 or less, still more preferably 80000 or less. The Mw of component (A) can be measured as a value in terms of polystyrene by gel permeation chromatography (GPC) method.

[0080] (A) component's weight-average molecular weight is preferably 5000 or more, more preferably 8000 or more, still more preferably 10000 or more, and preferably 100000 or less, more preferably 80000 or less, still more preferably 50000 or less. The weight-average molecular weight means the weight-average molecular weight based on the content ratio of the (A) component present in the resin composition layer. For example, when the resin composition layer contains the (A) component with a weight-average molecular weight of Mw1 and a content of w1 and the (A) component with a weight-average molecular weight of Mw2 and a content of w2, the weight-average molecular weight of the (A) component can be obtained by (Mw1×w1 + Mw2×w2) / (w1 + w2).

[0081] As the content of the (A) component, when the non-volatile component in the resin composition layer is 100% by mass, it is preferably 0.1% by mass or more, more preferably 0.15% by mass or more, still more preferably 0.2% by mass or more, 0.3% by mass or more, 0.4% by mass or more, 0.5% by mass or more, and preferably 30% by mass or less, more preferably 20% by mass or less, still more preferably 10% by mass or less, 8% by mass or less, 5% by mass or less, 4% by mass or less, 3% by mass or less, 3% by mass or less, 2% by mass or less, 1% by mass or less.

[0082] When the resin component in the resin composition layer is 100% by mass, the content of the (A) component is preferably 0.5% by mass or more, more preferably 1% by mass or more, still more preferably 1.5% by mass or more, and preferably 40% by mass or less, more preferably 30% by mass or less, still more preferably 20% by mass or less, 10% by mass or less, 5% by mass or less.

[0083] -(B) Phenoxy resin- The resin composition layer contains a (B) phenoxy resin as the (B) component. The (B) phenoxy resin as this (B) component does not include those corresponding to the above-mentioned (A) component. By containing the (B) phenoxy resin in the resin composition layer, the stress during curing of the resin composition layer can be relaxed, the mechanical strength can be improved, and the film flexibility can also be improved. The (B) component may be used alone or in combination of two or more.

[0084] (B) The weight average molecular weight (Mw) of the phenoxy resin is preferably 5000 or more, more preferably 8000 or more, still more preferably 10000 or more. The upper limit of the Mw is not particularly limited, but is preferably 100000 or less, more preferably 80000 or less, still more preferably 50000 or less. The Mw of component (B) can be measured as a polystyrene-equivalent value by gel permeation chromatography (GPC).

[0085] (B) The weight average molecular weight of the phenoxy resin is preferably 5000 or more, more preferably 8000 or more, still more preferably 10000 or more, and preferably 100000 or less, more preferably 80000 or less, still more preferably 50000 or less. The weight average molecular weight means the weight average molecular weight based on the content ratio of component (B) present in the resin composition layer. The weight average molecular weight can be obtained, for example, when the resin composition layer contains component (B) with a weight average molecular weight of Mw3 and a content of w3 and component (B) with a weight average molecular weight of Mw4 and a content of w4, by (Mw3×w3 + Mw4×w4) / (w3 + w4).

[0086] When the weight average molecular weight of component (A) is a2 and the weight average molecular weight of component (B) is b2, a2 / b2 is preferably 0.01 or more, more preferably 0.05 or more, still more preferably 0.1 or more, 0.15 or more, 0.2 or more, 0.25 or more, and preferably 10 or less, more preferably 8 or less, still more preferably 5 or less, 4 or less, 3 or less, 2 or less. By including components (A) and (B) in the resin composition layer such that a2 / b2 is within such a range, the glass transition temperature is high, the film flexibility is excellent, and the mechanical strength of the cured product of the resin composition layer is excellent.

[0087] (B) Examples of the phenoxy resin include a phenoxy resin having one or more skeletons selected from the group consisting of a bisphenol A skeleton, a bisphenol F skeleton, a bisphenol S skeleton, a bisphenol acetophenone skeleton, a novolac skeleton, a biphenyl skeleton, a fluorene skeleton, a dicyclopentadiene skeleton, a norbornene skeleton, a naphthalene skeleton, an anthracene skeleton, an adamantane skeleton, a terpene skeleton, and a trimethylcyclohexane skeleton. The terminal of the (B) phenoxy resin may be any functional group such as a phenolic hydroxyl group or an epoxy group.

[0088] (B) Commercially available products of the phenoxy resin include, for example, "1256" and "4250" manufactured by Mitsubishi Chemical Corporation (both are bisphenol A skeleton-containing phenoxy resins); "YX8100" manufactured by Mitsubishi Chemical Corporation (bisphenol S skeleton-containing phenoxy resin); "YX6954" manufactured by Mitsubishi Chemical Corporation (bisphenol acetophenone skeleton-containing phenoxy resin); "FX280" and "FX293" manufactured by Nippon Steel Chemical & Material Co., Ltd.; "YL7500BH30", "YX6954BH30", "YX7553", "YX7553BH30", "YL7891BH30", "YX7200B35", "YL7769BH30", "YL6794", "YL7213", "YL7290", and "YL7482" manufactured by Mitsubishi Chemical Corporation; etc.

[0089] (B) When the non-volatile components in the resin composition layer are 100% by mass, the content of the (B) component is preferably 0.1% by mass or more, more preferably 0.15% by mass or more, still more preferably 0.2% by mass or more, and preferably 15% by mass or less, more preferably 10% by mass or less, still more preferably 8% by mass or less, 7% by mass or less, 5% by mass or less.

[0090] (B) When the resin components in the resin composition layer are 100% by mass, the content of the (B) component is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, still more preferably 1% by mass or more, 1.5% by mass or more, 2% by mass or more, and preferably 25% by mass or less, more preferably 20% by mass or less, still more preferably 10% by mass or less, 8% by mass or less.

[0091] When the content of component (A) is defined as a1 and the content of component (B) is defined as b1, both based on 100% by mass of the resin component in the resin composition layer, a1 / b1 is 0.05 or more, preferably 0.1 or more, more preferably 0.15 or more, and even more preferably 0.2 or more. The upper limit is 50 or less, preferably 45 or less, more preferably 40 or less, even more preferably 35 or less, 30 or less, 25 or less, 20 or less, 15 or less, 10 or less, 5 or less, or 4 or less. By adjusting the contents of component (A) and component (B) so that a1 / b1 falls within such a range, it becomes possible to obtain a cured product having a high glass transition temperature and excellent film flexibility and mechanical strength.

[0092] As the total content of component (A) and component (B), when the non-volatile components in the resin composition layer are 100% by mass, it is preferably 0.2% by mass or more, more preferably 0.3% by mass or more, and even more preferably 0.4% by mass or more, and preferably 45% by mass or less, more preferably 30% by mass or less, and even more preferably 20% by mass or less.

[0093] -(C) Inorganic filler- The resin composition layer contains an inorganic filler as component (C). By using a resin composition layer containing component (C), a cured product having a low dielectric constant and a low dielectric tangent can be obtained. The (C) inorganic filler may be used alone or in combination of two or more in any ratio.

[0094] (C) The inorganic filler is contained in the resin composition layer in a particulate state. As the material of the (C) inorganic filler, an inorganic compound is used. As the material of the (C) inorganic filler, for example, silica, alumina, glass, cordierite, silicon oxide, barium sulfate, barium carbonate, talc, clay, mica powder, zinc oxide, hydrotalcite, boehmite, aluminum hydroxide, magnesium hydroxide, calcium carbonate, magnesium carbonate, magnesium oxide, boron nitride, aluminum nitride, manganese nitride, aluminum borate, strontium carbonate, strontium titanate, calcium titanate, magnesium titanate, bismuth titanate, titanium oxide, zirconium oxide, barium titanate, barium zirconate titanate, barium zirconate, calcium zirconate, zirconium phosphate, and zirconium tungstate phosphate, etc. may be mentioned. Among these, silica is particularly preferred. As silica, for example, amorphous silica, fused silica, crystalline silica, synthetic silica, hollow silica, etc. may be mentioned. Also, spherical silica is preferred as silica.

[0095] (C) Examples of commercially available products of the inorganic filler include "SP60-05", "SP507-05" manufactured by Nippon Steel Chemical & Material Co., Ltd.; "YC100C", "YA050C", "YA050C-MJE", "YA010C", "SC2500SQ", "SO-C4", "SO-C2", "SO-C1" manufactured by Admatechs Co., Ltd.; "UFP-30", "DAW-03", "FB-105FD" manufactured by Denka Co., Ltd.; "Silfill NSS-3N", "Silfill NSS-4N", "Silfill NSS-5N" manufactured by Tokuyama Corporation; "Celsifers", "MGH-005" manufactured by Taiheiyo Cement Corporation; and the like.

[0096] (C) The average particle size of the inorganic filler is not particularly limited, but is preferably 10 μm or less, more preferably 5 μm or less, still more preferably 3 μm or less, even more preferably 2 μm or less, and particularly preferably 1.5 μm or less. The lower limit of the average particle size of the (C) inorganic filler is not particularly limited, but is preferably 0.01 μm or more, more preferably 0.05 μm or more, still more preferably 0.1 μm or more, and particularly preferably 0.2 μm or more. The average particle size of the (C) inorganic filler can be measured by the laser diffraction / scattering method based on the Mie scattering theory. Specifically, it can be measured by creating a volume-based particle size distribution of the inorganic filler with a laser diffraction / scattering type particle size distribution measuring device and taking the median diameter thereof as the average particle size. As the measurement sample, 100 mg of the inorganic filler and 10 g of methyl ethyl ketone can be weighed into a vial and dispersed by ultrasonic waves for 10 minutes. The measurement sample is used to measure the volume-based particle size distribution of the inorganic filler using a laser diffraction type particle size distribution measuring device with the wavelengths of the light sources used being blue and red and in a flow cell method, and the average particle size is calculated as the median diameter from the obtained particle size distribution. Examples of the laser diffraction type particle size distribution measuring device include "LA-960" manufactured by Horiba, Ltd.

[0097] (C) The specific surface area of the inorganic filler is not particularly limited, but is preferably 0.1 m 2 / g or more, more preferably 0.5 m 2 / g or more, still more preferably 1 m 2 / g or more, and particularly preferably 3 m 2 / g or more. The upper limit of the specific surface area of the (C) inorganic filler is not particularly limited, but is preferably 100 m 2 / g or less, more preferably 70 m 2 / g or less, still more preferably 50 m 2 / g or less, even more preferably 30 m 2 / g or less, and particularly preferably 10 m 2It is below / g. The specific surface area of the inorganic filler is obtained by adsorbing nitrogen gas on the sample surface using a specific surface area measuring device (Macsorb HM-1210 manufactured by Mountech Co., Ltd.) according to the BET method and calculating the specific surface area using the BET multi-point method.

[0098] (C) From the viewpoints of enhancing moisture resistance and dispersibility, the inorganic filler is preferably treated with a surface treatment agent. Examples of the surface treatment agent include fluorine-containing silane coupling agents, aminosilane-based coupling agents, epoxysilane-based coupling agents, mercaptosilane-based coupling agents, silane-based coupling agents, alkoxysilanes, organosilazane compounds, titanate-based coupling agents, and the like. Further, the surface treatment agent may be used alone or in any combination of two or more.

[0099] Examples of commercially available surface treatment agents include "KBM403" (3-glycidoxypropyltrimethoxysilane) manufactured by Shin-Etsu Chemical Co., Ltd., "KBM803" (3-mercaptopropyltrimethoxysilane) manufactured by Shin-Etsu Chemical Co., Ltd., "KBE903" (3-aminopropyltriethoxysilane) manufactured by Shin-Etsu Chemical Co., Ltd., "KBM573" (N-phenyl-3-aminopropyltrimethoxysilane) manufactured by Shin-Etsu Chemical Co., Ltd., "SZ-31" (hexamethyldisilazane) manufactured by Shin-Etsu Chemical Co., Ltd., "KBM103" (phenyltrimethoxysilane) manufactured by Shin-Etsu Chemical Co., Ltd., "KBM-4803" (long-chain epoxy type silane coupling agent) manufactured by Shin-Etsu Chemical Co., Ltd., "KBM-7103" (3,3,3-trifluoropropyltrimethoxysilane) manufactured by Shin-Etsu Chemical Co., Ltd., and the like.

[0100] From the viewpoint of improving the dispersibility of the inorganic filler, the degree of surface treatment with the surface treatment agent preferably falls within a predetermined range. Specifically, 100% by mass of the inorganic filler is preferably surface-treated with 0.2% to 5% by mass of the surface treatment agent, more preferably surface-treated with 0.2% to 3% by mass, and even more preferably surface-treated with 0.3% to 2% by mass.

[0101] The degree of surface treatment with the surface treatment agent can be evaluated by the amount of carbon per unit surface area of the inorganic filler. From the viewpoint of improving the dispersibility of the inorganic filler, the amount of carbon per unit surface area of the inorganic filler is preferably 0.02 mg / m 2 or more, more preferably 0.1 mg / m 2 or more, and even more preferably 0.2 mg / m 2 or more. On the other hand, from the viewpoint of preventing an increase in the melt viscosity of the resin composition layer and the melt viscosity in the sheet form, the amount of carbon per unit surface area of the inorganic filler is preferably 1.0 mg / m 2 or less, more preferably 0.8 mg / m 2 or less, and even more preferably 0.5 mg / m 2 or less.

[0102] (C) The amount of carbon per unit surface area of the inorganic filler can be measured after washing the surface-treated inorganic filler with a solvent (for example, methyl ethyl ketone (MEK)). Specifically, a sufficient amount of MEK as a solvent is added to the inorganic filler surface-treated with the surface treatment agent, and ultrasonic cleaning is performed at 25 °C for 5 minutes. After removing the supernatant and drying the solid content, the amount of carbon per unit surface area of the inorganic filler can be measured using a carbon analyzer. As the carbon analyzer, "EMIA-320V" manufactured by Horiba, Ltd. can be used.

[0103] (C) When the non-volatile components in the resin composition layer are 100% by mass, the content of the inorganic filler is preferably 35% by mass or more, more preferably 40% by mass or more, and even more preferably 50% by mass or more. The upper limit is preferably 85% by mass or less, more preferably 80% by mass or less, and even more preferably 75% by mass or less.

[0104] -(D) Thermosetting resin- The resin composition layer may contain a (D) thermosetting resin as the (D) component. The (D) thermosetting resin as the (D) component excludes those corresponding to the (A) to (C) components. The type of the (D) thermosetting resin is not particularly limited as long as it can be cured by heat. The (D) thermosetting resin may be used alone or in combination of two or more.

[0105] Examples of the (D) thermosetting resin include epoxy resins, radically polymerizable resins, phenol resins, cyanate resins, active ester resins, carbodiimide resins, acid anhydride resins, amine resins, benzoxazine resins, and thiol resins. The thermosetting resin may be used alone or in combination of two or more.

[0106] From the viewpoint of significantly obtaining the effects of the present invention, the (D) thermosetting resin is preferably used in combination with an epoxy resin and a resin that can react with the epoxy resin to cure the resin composition layer. A resin that can react with the epoxy resin to cure the resin composition layer may be hereinafter referred to as a "curing agent". Examples of the curing agent include, for example, phenol resins, cyanate resins, active ester resins, carbodiimide resins, acid anhydride resins, amine resins, benzoxazine resins, and thiol resins. Among them, as the curing agent, phenol resins and active ester resins are preferable. The curing agent may be used alone or in combination of two or more. As one embodiment, the thermosetting resin includes an epoxy resin and a phenol resin.

[0107] Epoxy resin is a thermosetting resin having an epoxy group. Examples of epoxy resins include tetramethyl bisphenol type epoxy resin, biphenyl type epoxy resin, naphthalene type epoxy resin, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, bisphenol AF type epoxy resin, dicyclopentadiene type epoxy resin, tris phenol type epoxy resin, naphthol novolak type epoxy resin, phenol novolak type epoxy resin, tert-butyl-catechol type epoxy resin, naphthol type epoxy resin, anthracene type epoxy resin, glycidyl amine type epoxy resin, glycidyl ester type epoxy resin, cresol novolak type epoxy resin, phenol aralkyl type epoxy resin, linear aliphatic epoxy resin, epoxy resin having a butadiene structure, alicyclic epoxy resin, heterocyclic epoxy resin, spiro ring-containing epoxy resin, cyclohexane type epoxy resin, cyclohexanedimethanol type epoxy resin, naphthylene ether type epoxy resin, trimethylol type epoxy resin, tetraphenylethane type epoxy resin, isocyanurate type epoxy resin, phenolphthalimide type epoxy resin, etc. The epoxy resin may be used alone or in combination of two or more types.

[0108] (D) The thermosetting resin preferably contains, as the epoxy resin, an epoxy resin having two or more epoxy groups in one molecule. The proportion of the epoxy resin having two or more epoxy groups in one molecule is preferably 50% by mass or more, more preferably 60% by mass or more, particularly preferably 70% by mass or more, and usually 100% by mass or less with respect to 100% by mass of the epoxy resin.

[0109] Epoxy resins include liquid epoxy resins (hereinafter sometimes referred to as "liquid epoxy resins") that are liquid at a temperature of 20°C and solid epoxy resins (hereinafter sometimes referred to as "solid epoxy resins") that are solid at a temperature of 20°C. The resin composition layer may contain only a liquid epoxy resin as the epoxy resin, or may contain only a solid epoxy resin, or may contain a combination of a liquid epoxy resin and a solid epoxy resin.

[0110] As the liquid epoxy resin, a liquid epoxy resin having two or more epoxy groups in one molecule is preferred.

[0111] Preferred liquid epoxy resins include bisphenol A type epoxy resins, bisphenol F type epoxy resins, bisphenol AF type epoxy resins, naphthalene type epoxy resins, glycidyl ester type epoxy resins, glycidyl amine type epoxy resins, phenol novolac type epoxy resins, alicyclic epoxy resins having an ester skeleton, cyclohexane type epoxy resins, cyclohexanedimethanol type epoxy resins, and epoxy resins having a butadiene structure. More preferred are glycidyl amine type epoxy resins, bisphenol A type epoxy resins, and bisphenol F type epoxy resins. Even more preferred are bisphenol A type epoxy resins and bisphenol F type epoxy resins.

[0112] Specific examples of the liquid epoxy resin include "HP4032", "HP4032D", "HP4032SS" (naphthalene-type epoxy resin) manufactured by DIC Corporation; "828US", "828EL", "jER828EL", "825", "Epicoat 828EL" (bisphenol A-type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "jER807", "1750" (bisphenol F-type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "jER152" (phenol novolac-type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "630", "630LSD", "604" (glycidylamine-type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "ED-523T" (glycerol-type epoxy resin) manufactured by ADEKA Corporation; "EP-3950L", "EP-3980S" (glycidylamine-type epoxy resin) manufactured by ADEKA Corporation; "EP-4088S" (dicyclopentadiene-type epoxy resin) manufactured by ADEKA Corporation; "ZX1059" (a mixture of bisphenol A-type epoxy resin and bisphenol F-type epoxy resin) manufactured by Nippon Steel Chemical & 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", "JP-100", "JP-200" (epoxy resin having a butadiene structure (epoxidized polybutadiene resin)) manufactured by Nippon Soda Co., Ltd.; "ZX1658", "ZX1658GS" (liquid 1,4-glycidylcyclohexane-type epoxy resin) manufactured by Nippon Steel Chemical & Material Co., Ltd., etc. These may be used alone or in combination of two or more.

[0113] As the solid epoxy resin, a solid epoxy resin having three or more epoxy groups in one molecule is preferred, and an aromatic solid epoxy resin having three or more epoxy groups in one molecule is more preferred.

[0114] Examples of the solid epoxy resin include tetramethyl bisphenol type epoxy resin (bixylenol type epoxy resin), naphthalene type epoxy resin, naphthalene type tetrafunctional epoxy resin, naphthol novolak type epoxy resin, cresol novolak type epoxy resin, dicyclopentadiene type epoxy resin, trisphenol type epoxy resin, naphthol type epoxy resin, biphenyl type epoxy resin, naphthylene ether type epoxy resin, anthracene type epoxy resin, bisphenol A type epoxy resin, bisphenol AF type epoxy resin, phenol aralkyl type epoxy resin, tetraphenylethane type epoxy resin, and phenol phthalimide type epoxy resin. Bixylenol type epoxy resin and biphenyl type epoxy resin are preferred, and bixylenol type epoxy resin and biphenyl type epoxy resin are more preferred.

[0115] Specific examples of solid epoxy resins include "HP4032H" (naphthalene-type epoxy resin) manufactured by DIC Corporation; "HP-4700", "HP-4710" (naphthalene-type tetrafunctional epoxy resin) manufactured by DIC Corporation; "N-690" (cresol novolak-type epoxy resin) manufactured by DIC Corporation; "N-695" (cresol novolak-type epoxy resin) manufactured by DIC Corporation; "HP-7200", "HP-7200HH", "HP-7200H", "HP-7200L" (dicyclopentadiene-type epoxy resin) manufactured by DIC Corporation; "EXA-7311", "EXA-7311-G3", "EXA-7311-G4", "EXA-7311-G4S", "HP6000" (naphthylene ether-type epoxy resin) manufactured by DIC Corporation; "EPPN-502H" (trisphenol-type epoxy resin) manufactured by Nippon Kayaku Co., Ltd.; "NC7000L" (naphthol novolak-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", "ESN4100V" (naphthalene-type epoxy resin) manufactured by Nippon Steel Chemical & Material Co., Ltd.; "ESN485" (naphthol-type epoxy resin) manufactured by Nippon Steel Chemical & Material Co., Ltd.; "ESN375" (dihydroxynaphthalene-type epoxy resin) manufactured by Nippon Steel Chemical & Material Co., Ltd.; "YX4000H", "YX4000", "YX4000HK", "YL7890" (bixylenol-type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "YL6121" (biphenyl-type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "YX8800" (anthracene-type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "YX7700" (phenol aralkyl-type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "PG-100", "CG-500" manufactured by Osaka Gas Chemical 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; "WHR991S" (phenolphthalimide-type epoxy resin) manufactured by Nippon Kayaku Co., Ltd., and the like.These may be used individually or in combination of two or more types.

[0116] When using a combination of a liquid epoxy resin and a solid epoxy resin as the epoxy resin, their mass ratio (liquid epoxy resin: solid epoxy resin) is preferably 1:0.01 to 1:20, more preferably 1:0.05 to 1:10, and particularly preferably 1:0.1 to 1:7.

[0117] 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., still 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.

[0118] The weight average molecular weight (Mw) of the epoxy resin is preferably 100 to 5,000, more preferably 250 to 3,000, and still more preferably 400 to 1,500. The weight average molecular weight of the resin can be measured as a value in terms of polystyrene by the gel permeation chromatography (GPC) method.

[0119] (D) When the non-volatile components in the resin composition layer are 100% by mass, the content of the epoxy resin as the thermosetting resin is preferably 1% by mass or more, more preferably 5% by mass or more, and particularly preferably 10% by mass or more, and preferably 45% by mass or less, more preferably 40% by mass or less, and particularly preferably 30% by mass or less.

[0120] (D) When the resin components in the resin composition layer are 100% by mass, the content of the epoxy resin as the thermosetting resin is preferably 20% by mass or more, more preferably 25% by mass or more, and particularly preferably 30% by mass or more, and preferably 75% by mass or less, more preferably 70% by mass or less, and particularly preferably 65% by mass or less.

[0121] (D) As the radically polymerizable resin, as long as it has one or more (preferably two or more) radically polymerizable unsaturated groups in one molecule, its type is not particularly limited. Examples of the radically polymerizable resin include resins having one or more selected from maleimide groups, vinyl groups, allyl groups, styryl groups, vinylphenyl groups, acryloyl groups, methacryloyl groups, fumaroyl groups, and maleoyl groups as the radically polymerizable unsaturated groups. Among them, from the viewpoint of significantly obtaining the effects of the present invention, the radically polymerizable resin is preferably a maleimide resin.

[0122] As the maleimide resin, as long as it has one or more (preferably two or more) maleimide groups (2,5-dihydro-2,5-dioxo-1H-pyrrol-1-yl groups) in one molecule, its type is not particularly limited. Examples of the maleimide resin include (1) maleimide resins containing an aliphatic skeleton (preferably an aliphatic skeleton having 36 carbon atoms derived from dimer diamine) such as "BMI-3000J", "BMI-5000", "BMI-1400", "BMI-1500", "BMI-1700", "BMI-689" (all manufactured by Designer Molecules Inc.), "SLK6895-T90" (manufactured by Shin-Etsu Chemical Co., Ltd.); (2) maleimide resins containing an indane skeleton described in Japanese Patent Application Laid-Open No. 2020-500211; and (3) maleimide resins containing an aromatic ring skeleton directly bonded to the nitrogen atom of the maleimide group such as "MIR-3000-70MT" (manufactured by Nippon Kayaku Co., Ltd.), "BMI-4000" (manufactured by Daiwa Kasei Co., Ltd.), and "BMI-80" (manufactured by KAI Chemical Co., Ltd.).

[0123] (Meta)acrylic resins are not particularly limited in type as long as they have one or more (preferably two or more) (meta)acryloyl groups in one molecule, and they may be monomers or oligomers. Here, the term "(meta)acryloyl group" is a general term for acryloyl groups and methacryloyl groups. Examples of (meta)acrylic resins include, in addition to (meta)acrylate monomers, for example, "(A-DOG)" (manufactured by Shin-Nakamura Chemical Co., Ltd.), "DCP-A" (manufactured by Kyoeisha Chemical Co., Ltd.), "NPGDA", "FM-400", "R-687", "THE-330", "PET-30", "DPHA" (all manufactured by Nippon Kayaku Co., Ltd.), etc.

[0124] (D) When the content of the radical-polymerizable resin as the thermosetting resin is based on 100% by mass of the non-volatile components in the resin composition layer, it is preferably 1% by mass or more, more preferably 1.5% by mass or more, still more preferably 2% by mass or more, and preferably 10% by mass or less, more preferably 5% by mass or less, still more preferably 3% by mass or less.

[0125] (D) When the content of the radical-polymerizable resin as the thermosetting resin is based on 100% by mass of the resin components in the resin composition layer, it is preferably 1% by mass or more, more preferably 2% by mass or more, still more preferably 3% by mass or more, and preferably 15% by mass or less, more preferably 10% by mass or less, still more preferably 8% by mass or less.

[0126] As the phenolic resin, a compound having one or more, preferably two or more hydroxyl groups bonded to an aromatic ring such as a benzene ring or a naphthalene ring in one molecule can be used. Since the phenolic resin can react with the epoxy resin to cure the resin composition layer when combined with the epoxy resin, it is sometimes referred to as a "phenolic curing agent". From the viewpoint of significantly obtaining the effects of the present invention, a phenolic resin having a novolak structure is preferable. Further, from the viewpoint of adhesion, a nitrogen-containing phenolic resin is preferable, and a phenolic resin containing a triazine skeleton is more preferable. Among them, from the viewpoint of significantly obtaining the effects of the present invention, a phenolic novolak resin containing a triazine skeleton is preferable. Specific examples of the phenolic resin include, for example, "MEH-7700", "MEH-7810", "MEH-7851" manufactured by Meiwa Kasei Co., Ltd., "NHN", "CBN", "GPH" manufactured by Nippon Kayaku Co., Ltd., "SN-170", "SN-180", "SN-190", "SN-475", "SN-485", "SN-495", "SN-375", "SN-395" manufactured by Nippon Steel Chemical & Material Co., Ltd., "LA-7052", "LA-7054", "LA-3018", "LA-3018-50P", "LA-1356", "TD2090", "TD-2090-60M", "KA-1163" manufactured by DIC Corporation, etc.

[0127] As the active ester resin, generally, compounds having two or more highly reactive ester groups in one molecule, such as phenol esters, thiophenol esters, N-hydroxyamine esters, esters of heterocyclic hydroxy compounds, etc., are preferably used. Since the active ester resin can react with the epoxy resin to cure the resin composition layer when combined with the epoxy resin, it is sometimes referred to as an "active ester-based curing agent". The active ester resin is preferably obtained by a condensation reaction of a carboxylic acid compound and / or a thiocarboxylic acid compound with a hydroxy compound and / or a thiol compound. Particularly from the viewpoint of improving the high-temperature reflow bulge resistance, an active ester resin obtained from a carboxylic acid compound and a hydroxy compound is preferred, and an active ester resin obtained from a carboxylic acid compound and a phenol compound and / or a naphthol compound is more preferred. Examples of the carboxylic acid compound include benzoic acid, acetic acid, succinic acid, maleic acid, itaconic acid, phthalic acid, isophthalic acid, terephthalic acid, pyromellitic acid, etc. Examples of the phenol compound or naphthol compound include hydroquinone, resorcinol, bisphenol A, bisphenol F, bisphenol S, phenolphthalein, methylated bisphenol A, methylated bisphenol F, methylated bisphenol S, phenol, o-cresol, m-cresol, p-cresol, catechol, α-naphthol, β-naphthol, 1,5-dihydroxynaphthalene, 1,6-dihydroxynaphthalene, 2,6-dihydroxynaphthalene, dihydroxybenzophenone, trihydroxybenzophenone, tetrahydroxybenzophenone, phloroglucin, benzenetriol, dicyclopentadiene-type diphenol compound, phenol novolak, etc. Here, the "dicyclopentadiene-type diphenol compound" refers to a diphenol compound obtained by condensing two molecules of phenol with one molecule of dicyclopentadiene.

[0128] Specifically, as the active ester resin, 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 novolak, and an active ester resin containing a benzoylated product of phenol novolak are preferable. Among them, it is more preferable that it is at least one selected from a dicyclopentadiene type active ester resin and a naphthalene type active ester resin. As the dicyclopentadiene type active ester resin, an active ester resin containing a dicyclopentadiene type diphenol structure is preferable.

[0129] Examples of commercially available products of the active ester resin include, for example, as the active ester resin containing a dicyclopentadiene type diphenol structure, "EXB9451", "EXB9460", "EXB9460S", "EXB-8000L", "EXB-8000L-65M", "EXB-8000L-65TM", "HPC-8000L-65TM", "HPC-8000L-65T", "HPC-8000", "HPC-8000-65T", "EXB-8000H" (manufactured by DIC Corporation); as the active ester resin containing a naphthalene structure, "EXB-8100L-65T", "EXB-8150-60T", "EXB-8150-62T", "EXB-9416-70BK", "HPC-8150-62T", "EXB-8" (manufactured by DIC Corporation); as the phosphorus-containing active ester resin, "EXB9401" (manufactured by DIC Corporation); as the active ester resin which is an acetylated product of phenol novolak, "DC808" (manufactured by Mitsubishi Chemical Corporation); as the active ester resin which is a benzoylated product of phenol novolak, "YLH1026", "YLH1030", "YLH1048" (manufactured by Mitsubishi Chemical Corporation); as the active ester resin containing a styryl group and a naphthalene structure, "PC1300-02-65MA" (manufactured by Air Water Incorporated), and the like.

[0130] As the cyanate resin, a compound having one or more, preferably two or more cyanate groups in one molecule can be used. Since the cyanate resin can react with the epoxy resin to cure the resin composition layer when combined with the epoxy resin, it is sometimes referred to as a "cyanate-based curing agent". Examples of the cyanate resin include bifunctional cyanate resins such as bisphenol A dicyanate, polyphenol cyanate (oligo(3-methylene-1,5-phenylene cyanate)), 4,4'-methylenebis(2,6-dimethylphenyl cyanate), 4,4'-ethylidenediphenyl dicyanate, hexafluorobisphenol A dicyanate, 2,2-bis(4-cyanate)phenylpropane, 1,1-bis(4-cyanatephenylmethane), bis(4-cyanate-3,5-dimethylphenyl)methane, 1,3-bis(4-cyanatephenyl-1-(methylethylidene))benzene, bis(4-cyanatephenyl)thioether, and bis(4-cyanatephenyl)ether; polyfunctional cyanate resins derived from phenol novolak and cresol novolak; prepolymers in which some of these cyanate resins are partially triazine-ized, and the like. Specific examples of the cyanate resin include "PT30" and "PT60" (both are phenol novolak type polyfunctional cyanate resins) manufactured by arxada, "BA230", "BA230S75" (a prepolymer in which part or all of bisphenol A dicyanate is triazine-ized to form a trimer), and the like.

[0131] As the carbodiimide resin, a compound having one or more, preferably two or more carbodiimide structures in one molecule can be used. Since the carbodiimide resin can react with an epoxy resin to cure the resin composition layer when combined with the epoxy resin, it is sometimes referred to as a "carbodiimide-based curing agent". Specific examples of the carbodiimide resin include aliphatic biscarbodiimides such as tetramethylene-bis(t-butylcarbodiimide) and cyclohexane bis(methylene-t-butylcarbodiimide); biscarbodiimides such as aromatic biscarbodiimides like phenylene-bis(xilylcarbodiimide); aliphatic polycarbodiimides such as polyhexamethylene carbodiimide, polytrimethylhexamethylene carbodiimide, polycyclohexylene carbodiimide, poly(methylenebiscyclohexylene carbodiimide), and poly(isophorone carbodiimide); aromatic polycarbodiimides such as poly(phenylene carbodiimide), poly(naphthylene carbodiimide), poly(tolylene carbodiimide), poly(methyldiisopropylphenylene carbodiimide), poly(triethylphenylene carbodiimide), poly(diethylphenylene carbodiimide), poly(triisopropylphenylene carbodiimide), poly(diisopropylphenylene carbodiimide), poly(xylene carbodiimide), poly(tetramethylxylene carbodiimide), poly(methylenediphenylene carbodiimide), and poly[methylenebis(methylphenylene) carbodiimide]. Commercially available products of the carbodiimide resin include, for example, "Carbodilite V-02B", "Carbodilite V-03", "Carbodilite V-04K", "Carbodilite V-07", and "Carbodilite V-09" manufactured by Nisshinbo Chemical Inc.; "Stabaxol P", "Stabaxol P400", "Hycadil 510", etc. manufactured by LANXESS Co., Ltd.

[0132] As the acid anhydride resin, a compound having one or more, preferably two or more acid anhydride groups in one molecule can be used. Since the acid anhydride resin can react with an epoxy resin to cure the resin composition layer when combined with an epoxy group, it is sometimes referred to as an "acid anhydride-based curing agent". Specific examples of the acid anhydride resin include phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, methyl nadic anhydride, hydrogenated methyl nadic anhydride, trialkyltetrahydrophthalic anhydride, dodecenyl succinic anhydride, 5-(2,5-dioxotetrahydro-3-furanyl)-3-methyl-3-cyclohexene-1,2-dicarboxylic anhydride, trimellitic anhydride, pyromellitic anhydride, benzophenone tetracarboxylic dianhydride, 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 polymer-type acid anhydrides such as styrene-maleic acid resin copolymerized from styrene and maleic acid. Commercially available products of the acid anhydride resin include, for example, "HNA-100", "MH-700", "MTA-15", "DDSA", "OSA" manufactured by Shin Nippon Rika Co., Ltd.; "YH-306", "YH-307" manufactured by Mitsubishi Chemical Corporation; "HN-2200", "HN-5500" manufactured by Resonaak Co., Ltd.; "EF-30", "EF-40", "EF-60", "EF-80" manufactured by Cray Valley Co., Ltd., etc.

[0133] As the amine resin, a compound having one or more, preferably two or more amino groups in one molecule can be used. Since the amine resin can react with an epoxy resin to cure the resin composition layer when combined with an epoxy group, it is sometimes referred to as an "amine-based curing agent". Examples of the amine resin include aliphatic amines, polyether amines, alicyclic amines, aromatic amines, etc. Among them, aromatic amines are preferred. The amine resin is preferably a primary amine or a secondary amine, and more preferably a primary amine. Specific examples of the amine resin include 4,4'-methylenebis(2,6-dimethylaniline), 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylsulfone, 3,3'-diaminodiphenylsulfone, m-phenylenediamine, m-xylylenediamine, diethyltoluenediamine, 4,4'-diaminodiphenyl ether, 3,3'-dimethyl-4,4'-diaminobiphenyl, 2,2'-dimethyl-4,4'-diaminobiphenyl, 3,3'-dihydroxybenzidine, 2,2-bis(3-amino-4-hydroxyphenyl)propane, 3,3-dimethyl-5,5-diethyl-4,4-diphenylmethanediamine, 2,2-bis(4-aminophenyl)propane, 2,2-bis(4-(4-aminophenoxy)phenyl)propane, 1,3-bis(3-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, 1,4-bis(4-aminophenoxy)benzene, 4,4'-bis(4-aminophenoxy)biphenyl, bis(4-(4-aminophenoxy)phenyl)sulfone, bis(4-(3-aminophenoxy)phenyl)sulfone, etc. Commercially available products of the amine resin include, for example, "SEIKACURE-S" manufactured by Seika Corporation; "KAYABOND C-200S", "KAYABOND C-100", "KAYAHARD A-A", "KAYAHARD A-B", "KAYAHARD A-S" manufactured by Nippon Kayaku Co., Ltd.; "EPICURE W" manufactured by Mitsubishi Chemical Corporation; "DTDA" manufactured by Sumitomo Seika Chemicals Co., Ltd., etc.

[0134] Since a benzoxazine resin can react with an epoxy resin to cure a resin composition layer when combined with the epoxy resin, it is sometimes referred to as a "benzoxazine-based curing agent". Specific examples of benzoxazine resins include "JBZ-OP100D" and "ODA-BOZ" manufactured by JFE Chemical Corporation; "HFB2006M" manufactured by Showa Highpolymer Co., Ltd.; "P-d" and "F-a" manufactured by Shikoku Kasei Kogyo Co., Ltd., etc.

[0135] Since a thiol resin can react with an epoxy resin to cure a resin composition layer when combined with the epoxy resin, it is sometimes referred to as a "thiol-based curing agent". Examples of thiol resins include trimethylolpropane tris(3-mercaptopropionate), pentaerythritol tetrakis(3-mercaptobutyrate), tris(3-mercaptopropyl)isocyanurate, etc.

[0136] The active group equivalent weight of the curing agent is preferably 50 g / eq. to 3000 g / eq., more preferably 100 g / eq. to 1000 g / eq., still more preferably 100 g / eq. to 500 g / eq., and particularly preferably 100 g / eq. to 300 g / eq. The active group equivalent weight is the mass of the curing agent per equivalent of the active group.

[0137] The weight average molecular weight (Mw) of the curing agent is preferably 100 to 5,000, more preferably 250 to 3,000, and still more preferably 400 to 1,500. The weight average molecular weight of the resin can be measured as a value in terms of polystyrene by the gel permeation chromatography (GPC) method.

[0138] When the epoxy equivalent of the epoxy resin is set to 1, the active hydrogen equivalent of the curing agent is preferably 0.01 or more, more preferably 0.05 or more, still more preferably 0.1 or more, and preferably 5 or less, more preferably 3 or less, particularly preferably 2 or less. The "epoxy equivalent of the epoxy resin" represents the total value obtained by dividing the mass of the epoxy resin present in the resin composition layer by the epoxy equivalent. The "active hydrogen equivalent of the curing agent" represents the total value obtained by dividing the mass of the curing agent present in the resin composition layer by the active hydrogen equivalent.

[0139] (D) When the non-volatile components in the resin composition layer are 100% by mass, the content of the curing agent as the thermosetting resin is preferably 1% by mass or more, more preferably 3% by mass or more, still more preferably 5% by mass or more, and preferably 20% by mass or less, more preferably 15% by mass or less, still more preferably 10% by mass or less.

[0140] (D) When the resin components in the resin composition layer are 100% by mass, the content of the curing agent as the thermosetting resin is preferably 10% by mass or more, more preferably 15% by mass or more, still more preferably 20% by mass or more, and preferably 50% by mass or less, more preferably 45% by mass or less, still more preferably 40% by mass or less.

[0141] (D) When the non-volatile components in the resin composition layer are 100% by mass, the content of the thermosetting resin is preferably 10% by mass or more, more preferably 15% by mass or more, still more preferably 20% by mass or more, and preferably 65% by mass or less, more preferably 50% by mass or less, still more preferably 45% by mass or less, 40% by mass or less.

[0142] (D) From the viewpoint of significantly obtaining the effects of the present invention, when the resin components in the resin composition layer are 100% by mass, the content of the thermosetting resin is preferably 40% by mass or more, more preferably 50% by mass or more, still more preferably 60% by mass or more, and preferably 90% by mass or less, more preferably 88% by mass or less, still more preferably 85% by mass or less.

[0143] When the total content of components (A) to (D) is 100% by mass of the non-volatile components in the resin composition layer, it is preferably 15% by mass or more, more preferably 20% by mass or more, still more preferably 25% by mass or more, and preferably 65% by mass or less, more preferably 60% by mass or less, still more preferably 60% by mass or less, 55% by mass or less, 50% by mass or less.

[0144] -(E) Thermoplastic resin- The resin composition layer may contain (E) thermoplastic resin as component (E). The (E) thermoplastic resin as this component (E) does not include those corresponding to the above-mentioned components (A) to (D). The component (E) may be used alone or in combination of two or more.

[0145] Examples of the (E) thermoplastic resin include polyvinyl acetal resin, polyolefin resin, polybutadiene resin, polyamideimide resin, polyetherimide resin, polysulfone resin, polyethersulfone resin, polyphenylene ether resin, polycarbonate resin, polyetheretherketone resin, polyester resin, etc. The (E) thermoplastic resin may be used alone or in combination of two or more.

[0146] Examples of the polyvinyl acetal resin include polyvinyl formal resin and polyvinyl butyral resin, and polyvinyl butyral resin is preferred. Specific examples of the polyvinyl acetal resin include Esrec BH series, BX series (e.g., BX-5Z), KS series (e.g., KS-1), BL series, BM series manufactured by Sekisui Chemical Co., Ltd.; etc.

[0147] Examples of the polyolefin resin include ethylene-based copolymer resins such as low-density polyethylene, ultra-low-density polyethylene, high-density polyethylene, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, ethylene-methyl acrylate copolymer; polyolefin polymers such as polypropylene, ethylene-propylene block copolymer, etc.

[0148] Examples of the polybutadiene resin include, for example, a resin containing a hydrogenated polybutadiene skeleton, a hydroxy group-containing polybutadiene resin, a phenolic hydroxy group-containing polybutadiene resin, a carboxy group-containing polybutadiene resin, an acid anhydride group-containing polybutadiene resin, an epoxy group-containing polybutadiene resin, an isocyanate group-containing polybutadiene resin, a urethane group-containing polybutadiene resin, a polyphenylene ether-polybutadiene resin, and the like.

[0149] Specific examples of the polyamideimide resin include "Vylon Max HR11NN" and "Vylon Max HR16NN" manufactured by Toyobo Co., Ltd. Specific examples of the polyamideimide resin also include modified polyamideimides such as "KS9100" and "KS9300" (polyamideimide containing a polysiloxane skeleton) manufactured by Resona Co., Ltd.

[0150] Specific examples of the polyethersulfone resin include "PES5003P" manufactured by Sumitomo Chemical Co., Ltd.

[0151] Specific examples of the polysulfone resin include polysulfones "P1700", "P3500", etc. manufactured by Solvay Advanced Polymers, LLC.

[0152] Specific examples of the polyphenylene ether resin include "NORYL SA90" manufactured by SABIC. Specific examples of the polyetherimide resin include "ULTEM" manufactured by GE. The polyphenylene ether resin may have one or more (preferably two or more) styryl groups or vinylphenyl groups in one molecule. Examples of such polyphenylene ether resins include, in addition to styrene monomer, for example, "OPE-2St", "OPE-2St 1200", "OPE-2St 2200" (all manufactured by Mitsubishi Gas Chemical Company, Inc.).

[0153] Examples of the polycarbonate resin include a hydroxy group-containing carbonate resin, a phenolic hydroxyl group-containing carbonate resin, a carboxy group-containing carbonate resin, an acid anhydride group-containing carbonate resin, an isocyanate group-containing carbonate resin, a urethane group-containing carbonate resin, and the like. Specific examples of the polycarbonate resin include "FPC-0220" manufactured by Mitsubishi Gas Chemical Company, "T6002", "T6001" (polycarbonate diol) manufactured by Asahi Kasei Corporation, "C-1090", "C-2090", "C-3090" (polycarbonate diol) manufactured by Kuraray Co., Ltd., and the like. Specific examples of the polyetheretherketone resin include "Sumipro EK" manufactured by Sumitomo Chemical Company, and the like.

[0154] Examples of the polyester resin include a polyethylene terephthalate resin, a polyethylene naphthalate resin, a polybutylene terephthalate resin, a polybutylene naphthalate resin, a polytrimethylene terephthalate resin, a polytrimethylene naphthalate resin, a polycyclohexanedimethylene terephthalate resin, and the like.

[0155] (E) The thermoplastic resin may be an organic filler that is insoluble in the solvent described below and exists in a particulate form in the resin composition layer. Examples of the organic filler include rubber particles, polyamide fine particles, silicone particles, core-shell type particles, and the like, and rubber particles are preferred.

[0156] Examples of the rubber component contained in the rubber particles include olefin-based thermoplastic elastomers such as polybutadiene, polyisoprene, polychlorobutadiene, ethylene-vinyl acetate copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-isobutylene copolymer, acrylonitrile-butadiene copolymer, isoprene-isobutylene copolymer, isobutylene-butadiene copolymer, ethylene-propylene-diene terpolymer, and ethylene-propylene-butene terpolymer; and thermoplastic elastomers such as acrylic-based thermoplastic elastomers like poly(propyl (meth)acrylate), poly(butyl (meth)acrylate), poly(cyclohexyl (meth)acrylate), and poly(octyl (meth)acrylate). Preferably, it is an olefin-based thermoplastic elastomer, and more preferably, it is a styrene-butadiene copolymer. Further, a silicone-based rubber such as polyorganosiloxane rubber may be mixed into the rubber component. The rubber component contained in the rubber particles has a glass transition temperature of, for example, 0 °C or lower, preferably -10 °C or lower, more preferably -20 °C or lower, and even more preferably -30 °C or lower.

[0157] As the rubber particles, commercially available products may be used. Examples thereof include "EXL2655" manufactured by Dow Chemical Japan, "AC3401N", "AC3816N", etc. manufactured by Aika Industries Co., Ltd.

[0158] The core-shell type particles are particulate organic fillers composed of core particles containing a rubber component as described above and one or more shell portions covering the core particles. Further, the core-shell type particles are preferably core-shell type graft copolymer particles composed of core particles containing a rubber component as described above and a shell portion obtained by graft copolymerizing a monomer component copolymerizable with the rubber component contained in the core particles. Here, the core-shell type does not necessarily refer only to those in which the core particles and the shell portion can be clearly distinguished. It also includes those in which the boundary between the core particles and the shell portion is unclear, and the core particles do not have to be completely covered by the shell portion.

[0159] The rubber component is preferably contained in the core-shell type graft copolymer particles in an amount of 40% by mass or more, more preferably 50% by mass or more, and even more preferably 60% by mass or more. The upper limit of the content of the rubber component in the core-shell type graft copolymer particles is not particularly limited, but from the viewpoint of sufficiently coating the core particles with the shell portion, for example, it is preferably 95% by mass or less, and preferably 90% by mass.

[0160] Examples of the monomer component forming the shell portion of the core-shell type graft copolymer particles include (meth)acrylic acid esters such as methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, cyclohexyl (meth)acrylate, octyl (meth)acrylate, and glycidyl (meth)acrylate; (meth)acrylic acid; N-substituted maleimides such as N-methylmaleimide and N-phenylmaleimide; maleimide; α,β-unsaturated carboxylic acids such as maleic acid and itaconic acid; aromatic vinyl compounds such as styrene, 4-vinyltoluene, and α-methylstyrene; and (meth)acrylonitrile. Among them, (meth)acrylic acid esters are preferred, and methyl (meth)acrylate is more preferred.

[0161] Examples of commercially available products of the core-shell type graft copolymer particles include "CHT" manufactured by Samsung SDI Co., Ltd.; "B602" manufactured by Techno UMG Co., Ltd.; "Paraloid EXL2602", "Paraloid EXL2603", "Paraloid EXL2655", "Paraloid EXL2311", "Paraloid EXL2313", "Paraloid EXL2315", "Paraloid KM330", "Paraloid KM336P", "Paraloid KCZ201" manufactured by Dow Chemical Japan Co., Ltd.; "Metablen C-223A", "Metablen E-901", "Metablen S-2001", "Metablen W-450A", "Metablen SRK-200" manufactured by Mitsubishi Rayon Co., Ltd.; "Kanekaes M-511", "Kanekaes M-600", "Kanekaes M-400", "Kanekaes M-580", "Kanekaes MR-01" manufactured by Kaneka Corporation. These may be used alone or in combination of two or more.

[0162] The average particle diameter (average primary particle diameter) of the core-shell type graft copolymer particles is not particularly limited, but is preferably 20 nm or more, more preferably 50 nm or more, still more preferably 80 nm or more, particularly preferably 100 nm or more, preferably 5,000 nm or less, more preferably 2,000 nm or less, still more preferably 1,000 nm or less, and particularly preferably 500 nm or less. The average particle diameter (average primary particle diameter) of the core-shell type graft copolymer particles can be measured using a zeta potential particle size distribution measuring device or the like.

[0163] (E) The weight average molecular weight (Mw) of the thermoplastic resin is preferably greater than 5,000, more preferably 8,000 or more, still more preferably 10,000 or more, particularly preferably 20,000 or more, and preferably 100,000 or less, more preferably 70,000 or less, still more preferably 60,000 or less, and particularly preferably 50,000 or less.

[0164] (E) When the non-volatile component of the resin composition layer is 100% by mass, the content of the (E) component is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, still more preferably 1% by mass or more, and preferably 5% by mass or less, more preferably 3% by mass or less, and still more preferably 2% by mass or less.

[0165] (E) When the resin component of the resin composition layer is 100% by mass, the content of the (E) component is preferably 1% by mass or more, more preferably 1.5% by mass or more, still more preferably 2% by mass or more, and preferably 5% by mass or less, more preferably 4% by mass or less, and still more preferably 3% by mass or less.

[0166] When the content of component (E) is defined as e1 based on 100% by mass of the resin component in the resin composition layer, (a1 + b1) / (a1 + b1 + e1) is preferably 0.6 or more, more preferably 0.7 or more, still more preferably 0.8 or more, and preferably 5 or less, more preferably 3 or less, still more preferably 1.5 or less. By adjusting the amounts of component (A), component (B), and component (E) such that (a1 + b1) / (a1 + b1 + e1) falls within such a range, it becomes possible to further improve the film flexibility.

[0167] -(F) Flame retardant- The resin composition layer may contain an (F) flame retardant as component (F). The (F) flame retardant as this component (F) does not include those corresponding to the above-mentioned components (A) to (E). By containing the (F) flame retardant, the (F) flame retardant can react with the epoxy resin in component (D), making it possible to further improve the glass transition temperature and flame retardancy of the cured product. Component (F) may be used alone or in combination of two or more.

[0168] Examples of the (F) flame retardant include phosphazene compounds, organic phosphorus-based flame retardants, organic nitrogen-containing phosphorus compounds, nitrogen compounds, silicone-based flame retardants, metal hydroxides, etc., and phosphazene compounds are preferred. The flame retardant may be used alone or in combination of two or more.

[0169] The phosphazene compound is not particularly limited as long as it is a cyclic compound having nitrogen and phosphorus as constituent elements, but the phosphazene compound is preferably a phosphazene compound having a phenolic hydroxyl group.

[0170] Specific examples of the phosphazene compound include, for example, "SPH-100", "SPS-100", "SPB-100", "SPE-100" manufactured by Otsuka Chemical Co., Ltd., "FP-100", "FP-110", "FP-300", "FP-400" manufactured by Fushimi Pharmaceutical Co., Ltd., etc., and "SPH-100" manufactured by Otsuka Chemical Co., Ltd. is preferred.

[0171] As the flame retardant other than the phosphazene compound, commercially available products may be used. For example, "HCA-HQ" manufactured by Sanko Chemical Co., Ltd., "PX-200" manufactured by Daihachi Chemical Industry Co., Ltd., etc. may be mentioned. As the flame retardant, those that are difficult to hydrolyze are preferable. For example, 10-(2,5-dihydroxyphenyl)-10-hydroxy-9-oxa-10-phosphaphenanthrene-10-oxide, etc. are preferable.

[0172] (F) When the non-volatile components in the resin composition layer are taken as 100% by mass, the content of the flame retardant is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, still more preferably 1% by mass or more, and preferably 5% by mass or less, more preferably 3% by mass or less, still more preferably 2% by mass or less.

[0173] (F) When the resin components in the resin composition layer are taken as 100% by mass, the content of the flame retardant is preferably 1% by mass or more, more preferably 1.5% by mass or more, still more preferably 2% by mass or more, and preferably 15% by mass or less, more preferably 10% by mass or less, still more preferably 8% by mass or less.

[0174] (A) When the non-volatile components in the resin composition layer are taken as 100% by mass, the total content of components (D) and (F) is preferably 15% by mass or more, more preferably 20% by mass or more, still more preferably 25% by mass or more, and preferably 65% by mass or less, more preferably 60% by mass or less, still more preferably 60% by mass or less, 55% by mass or less, 50% by mass or less.

[0175] -(G) Curing accelerator- The resin composition layer may contain a (G) curing accelerator as the (G) component. The (G) curing accelerator as the (G) component does not include those corresponding to the above-mentioned components (A) to (F). The (G) curing accelerator has a function as a curing catalyst that promotes the curing of the epoxy resin in the (D) component.

[0176] (G) As a curing accelerator, a compound that accelerates the curing of the epoxy resin can be used. Examples of such (G) curing accelerators 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, and the like. The (G) curing accelerator may be used alone or in combination of two or more.

[0177] Examples of phosphorus-based hardening accelerators include aliphatic phosphonium salts such as tetrabutylphosphonium bromide, tetrabutylphosphonium chloride, tetrabutylphosphonium acetate, tetrabutylphosphonium decanoate, tetrabutylphosphonium laurate, bis(tetrabutylphosphonium) pyromellitate, tetrabutylphosphonium hydrogen hexahydrophthalate, tetrabutylphosphonium 2,6-bis[(2-hydroxy-5-methylphenyl)methyl]-4-methylphenolate, di-tert-butyldimethylphosphonium tetraphenylborate; aromatic phosphonium salts such as methyltriphenylphosphonium bromide, ethyltriphenylphosphonium bromide, propyltriphenylphosphonium bromide, butyltriphenylphosphonium bromide, benzyltriphenylphosphonium chloride, tetraphenylphosphonium bromide, p-tolyltriphenylphosphonium tetra-p-tolylborate, tetraphenylphosphonium tetraphenylborate, tetraphenylphosphonium tetra-p-tolylborate, triphenylethylphosphonium tetraphenylborate, tris(3-methylphenyl)ethylphosphonium tetraphenylborate, tris(2-methoxyphenyl)ethylphosphonium tetraphenylborate, (4-methylphenyl)triphenylphosphonium thiocyanate, tetraphenylphosphonium thiocyanate, butyltriphenylphosphonium thiocyanate; aromatic phosphine-borane complexes such as triphenylphosphine·triphenylborane; aromatic phosphine-quinone addition reactants such as triphenylphosphine·p-benzoquinone addition reactant; aliphatic phosphines such as tributylphosphine, tri-tert-butylphosphine, trioctylphosphine, di-tert-butyl(2-butenyl)phosphine, di-tert-butyl(3-methyl-2-butenyl)phosphine, tricyclohexylphosphine;Aromatic phosphines such as 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, 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, 2,2'-bis(diphenylphosphino)diphenylether, etc. are mentioned.;

[0178] Examples of the urea-based curing accelerators include, for example, 1,1-dimethylurea; aliphatic dimethylureas such as 1,1,3-trimethylurea, 3-ethyl-1,1-dimethylurea, 3-cyclohexyl-1,1-dimethylurea, 3-cyclooctyl-1,1-dimethylurea; aromatic dimethylureas such as 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, 3-(3,4-dimethylphenyl)-1,1-dimethylurea, 3-(4-isopropylphenyl)-1,1-dimethylurea, 3-(4-methoxyphenyl)-1,1-dimethylurea, 3-(4-nitrophenyl)-1,1-dimethylurea, 3-[4-(4-methoxyphenoxy)phenyl]-1,1-dimethylurea, 3-[4-(4-chlorophenoxy)phenyl]-1,1-dimethylurea, 3-[3-(trifluoromethyl)phenyl]-1,1-dimethylurea, N,N-(1,4-phenylene)bis(N’,N’-dimethylurea), N,N-(4-methyl-1,3-phenylene)bis(N’,N’-dimethylurea) [toluene bisdimethylurea], and the like.

[0179] Examples of the guanidine-based curing accelerators include, for example, 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, 1-(o-tolyl)biguanide, and the like.

[0180] Examples of imidazole-based curing accelerators include imidazole compounds such as 2-methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 1,2-dimethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 1-benzyl-2-methylimidazole, 1-benzyl-2-phenylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-undecylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 1-cyanoethyl-2-phenylimidazole, 1-cyanoethyl-2-undecylimidazolium trimellitate, 1-cyanoethyl-2-phenylimidazolium trimellitate, 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-undecylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-ethyl-4'-methylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine isocyanuric acid adduct, 2-phenylimidazole isocyanuric acid adduct, 2-phenyl-4,5-dihydroxymethylimidazole, 2-phenyl-4-methyl-5-hydroxymethylimidazole, 2,3-dihydro-1H-pyrrolo[1,2-a]benzimidazole, 1-dodecyl-2-methyl-3-benzylimidazolium chloride, 2-methylimidazoline, 2-phenylimidazoline, and adducts of imidazole compounds and epoxy resins. Commercially available products of imidazole-based curing accelerators include, for example, "1B2PZ", "2E4MZ", "2MZA-PW", "2MZ-OK", "2MA-OK", "2MA-OK-PW", "2PHZ", "2PHZ-PW", "Cl1Z", "Cl1Z-CN", "Cl1Z-CNS", "C11Z-A" manufactured by Shikoku Kasei Kogyo Co., Ltd.; "P200-H50" manufactured by Mitsubishi Chemical Corporation, etc.

[0181] Examples of the metal-based hardening accelerator include organometallic complexes or organometallic salts of metals such as cobalt, copper, zinc, iron, nickel, manganese, and tin. Specific examples of the organometallic complexes include organocobalt complexes such as cobalt(II) acetylacetonate and cobalt(III) acetylacetonate, organocopper complexes such as copper(II) acetylacetonate, organozinc complexes such as zinc(II) acetylacetonate, organoiron complexes such as iron(III) acetylacetonate, organonickel complexes such as nickel(II) acetylacetonate, and organomanganese complexes such as manganese(II) acetylacetonate. Examples of the organometallic salts include zinc octylate, tin octylate, zinc naphthenate, cobalt naphthenate, tin stearate, and zinc stearate.

[0182] Examples of the amine-based hardening accelerator include trialkylamines such as triethylamine and tributylamine, 4-dimethylaminopyridine, benzyldimethylamine, 2,4,6-tris(dimethylaminomethyl)phenol, 1,8-diazabicyclo(5,4,0)-undecene, and the like. As the amine-based hardening accelerator, commercially available products may be used. For example, "MY-25" manufactured by Ajinomoto Fine-Techno Co., Inc. and the like can be mentioned.

[0183] (G) When the non-volatile component in the resin composition layer is 100% by mass, the content of the hardening accelerator is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, still more preferably 0.1% by mass or more, and preferably 1.5% by mass or less, more preferably 1% by mass or less, still more preferably 0.5% by mass or less.

[0184] (G) When the resin component in the resin composition layer is 100% by mass, the content of the hardening accelerator is preferably 0.1% by mass or more, more preferably 0.2% by mass or more, still more preferably 0.3% by mass or more, and preferably 5% by mass or less, more preferably 3% by mass or less, still more preferably 2% by mass or less.

[0185] -(H) Other Additives- The resin composition layer may contain, as an optional non-volatile component, (H) other additives. Examples of (H) other additives include, for example, elastomers (excluding those corresponding to the (A) component, (B) component, and (E) component); polymerization initiators; organometallic compounds such as organic copper compounds, organic zinc compounds, and organic cobalt 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 benton 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 silane; adhesion imparting agents such as triazole-based adhesion imparting agents, tetrazole-based adhesion imparting agents, and triazine-based adhesion imparting agents; antioxidants such as hindered phenol-based antioxidants; fluorescent brighteners such as stilbene derivatives; surfactants such as fluorine-based surfactants and silicone-based surfactants; dispersants such as phosphate ester-based dispersants, polyoxyalkylene-based dispersants, acetylene-based dispersants, silicone-based dispersants, anionic dispersants, and cationic dispersants; stabilizers such as borate-based stabilizers, titanate-based stabilizers, aluminate-based stabilizers, zirconate-based stabilizers, isocyanate-based stabilizers, carboxylic acid-based stabilizers, and carboxylic anhydride-based stabilizers; photo-polymerization initiation aids such as tertiary amines; photosensitizers such as pyralizones, anthracenes, coumarins, xanthones, and thioxanthones. (H) Other additives may be used alone or in combination of two or more.

[0186] <(I) Solvent> The resin composition layer may further contain, as an optional volatile component, (I) a solvent in combination with the non-volatile components such as the above-described components (A) to (H). Usually, an organic solvent is used as the (I) solvent. Examples of the organic solvent include ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; ester solvents such as methyl acetate, ethyl acetate, butyl acetate, isobutyl acetate, isoamyl acetate, methyl propionate, ethyl propionate, and γ-butyrolactone; ether solvents such as tetrahydropyran, tetrahydrofuran, 1,4-dioxane, diethyl ether, diisopropyl ether, dibutyl ether, diphenyl ether, and anisole; alcohol solvents such as methanol, ethanol, propanol, butanol, and ethylene glycol; ether ester solvents such as 2-ethoxyethyl acetate, propylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, ethyl diglycol acetate, γ-butyrolactone, and methyl methoxypropionate; ester alcohol solvents such as methyl lactate, ethyl lactate, and methyl 2-hydroxyisobutyrate; ether alcohol solvents such as 2-methoxypropanol, 2-methoxyethanol, 2-ethoxyethanol, propylene glycol monomethyl ether, and diethylene glycol monobutyl ether (butyl carbitol); amide solvents such as N,N-dimethylformamide, N,N-dimethylacetamide, and N-methyl-2-pyrrolidone; sulfoxide solvents such as dimethyl sulfoxide; nitrile solvents such as acetonitrile and propionitrile; aliphatic hydrocarbon solvents such as hexane, cyclopentane, cyclohexane, and methylcyclohexane; aromatic hydrocarbon solvents such as benzene, toluene, xylene, ethylbenzene, and trimethylbenzene. The (I) solvent may be used alone or in combination of two or more.

[0187] (I) The amount of the solvent is not particularly limited, and 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, 10% by mass or less, etc., or even 0% by mass, based on 100% by mass of all the components of the resin composition layer.

[0188] From the viewpoints of thinning the circuit board and providing a cured product having excellent insulation even if the cured product of the resin composition layer is a thin film, the thickness of the resin composition layer is preferably 100 μm or less, more preferably 80 μm or less, and still more preferably 55 μm or less. The lower limit of the thickness of the resin composition layer is not particularly limited, but it can usually be 5 μm or more, 10 μm or more, etc.

[0189] <Protective film> The resin sheet with a metal foil includes a protective film. By laminating the protective film on the resin sheet with a metal foil, it is possible to suppress the adhesion of dust or the like and scratches on the surface of the resin composition layer.

[0190] Examples of the protective film include a film made of a plastic material, a metal foil, and a release paper, and a film made of a plastic material and a metal foil are preferable.

[0191] When using a film made of a plastic material as the protective film, examples of the plastic material include polyesters such as polyethylene terephthalate (hereinafter sometimes abbreviated as "PET"), polyethylene naphthalate (hereinafter sometimes abbreviated as "PEN"), polycarbonate (hereinafter sometimes abbreviated as "PC"), acrylics such as polymethyl methacrylate (PMMA), cyclic polyolefin, triacetyl cellulose (TAC), polyethersulfide (PES), polyether ketone, polyimide, and the like. Among them, polyethylene terephthalate and polyethylene naphthalate are preferable, and inexpensive polyethylene terephthalate is particularly preferable.

[0192] When using a metal foil as the protective film, examples of the metal foil include a copper foil and an aluminum foil, and a copper foil is preferable. As the copper foil, a foil made of single metal copper may be used, or a foil made of an alloy of copper and other metals (for example, tin, chromium, silver, magnesium, nickel, zirconium, silicon, titanium, etc.) may be used.

[0193] The protective film may be subjected to a matting treatment, a corona treatment, or an antistatic treatment on the surface that is joined to the resin composition layer.

[0194] Moreover, as the protective film, a protective film with a release layer having a release layer on the surface joined to the resin composition layer may be used. Examples of the release agent used for the release layer of the protective film with a release layer include one or more release agents selected from the group consisting of alkyd resins, polyolefin resins, urethane resins, and silicone resins. As the protective film with a release layer, commercially available products may be used. For example, "SK-1", "AL-5", "AL-7" manufactured by Lintec Corporation, which are PET films having a release layer mainly composed of an alkyd resin-based release agent, "Lumirror T60", "Lumirror R80", "Lumirror" manufactured by Toray Industries, Inc., "Purex" manufactured by Teijin Limited, "Unipile" manufactured by Unitika Ltd., etc.

[0195] The thickness of the protective film is not particularly limited, but is, for example, 1 μm to 40 μm. When the protective film has a multilayer structure such as a protective film with a release layer, it is preferable that the total thickness of the protective film is within such a range.

[0196] <Method for manufacturing a resin sheet with a metal foil> The method for manufacturing a resin sheet with a metal foil is, for example, to prepare a resin varnish in which the components contained in the resin composition layer are dissolved in a solvent, apply this resin varnish onto a protective film using a die coater or the like, and further dry it to form a resin composition layer on the protective film. Next, a resin sheet with a metal foil can be manufactured by laminating a metal foil on the surface of the resin composition layer using a roll laminator or the like. The solvents described above can be used for the solvent.

[0197] Drying may be carried out by known methods such as heating and hot air blowing. The drying conditions are not particularly limited, but drying is performed so that the content of the solvent in the resin composition layer falls within the above-described range. Although it varies depending on the boiling point of the solvent in the resin varnish, for example, when using a resin varnish containing 30% to 60% by mass of the solvent, the resin composition layer can be formed by drying at 50°C to 150°C for 3 minutes to 10 minutes.

[0198] The resin sheet with a metal foil can be wound up and stored in a roll shape. When using the resin sheet with a metal foil, it can be made usable by peeling off the protective film.

[0199] <Physical properties, etc. of the resin sheet with a metal foil> Since the resin sheet with a metal foil of the present invention has a resin composition layer containing components (A) and (B) combined in a predetermined ratio, it exhibits the characteristic that the glass transition temperature (Tg) of the cured product of the resin composition layer thermally cured by vacuum press treatment is high. The glass transition temperature of the cured product of the resin composition layer thermally cured by vacuum press treatment is preferably 150°C or higher, more preferably 155°C or higher, and even more preferably 160°C or higher. The upper limit of the glass transition temperature of the cured product is not particularly limited, but can be 300°C or lower, etc. The glass transition temperature can be measured by the method described in the examples below.

[0200] The resin sheet with a metal foil of the present invention exhibits the characteristic of excellent mechanical strength because the glass transition temperature (Tg) of the cured product of the resin composition layer is high. Therefore, it provides an insulating layer with excellent mechanical strength. Further, as a result of the increased mechanical strength of the cured product, it becomes possible to obtain a cured product with excellent bending resistance. The resin sheet with a metal foil from which the protective film has been removed is laminated on a copper foil such that the resin composition layer is in contact with the copper foil. After lamination, the resin composition layer is thermally cured by vacuum press treatment, the copper foil is removed, and a cured product for evaluation is obtained. Then, the cured product for evaluation is cut into test pieces having a width of 2 mm and a length of 80 mm, and the tensile strength is measured using a tensile testing machine. At this time, the tensile strength is preferably 100 MPa or more, more preferably 115 MPa or more. The upper limit is not particularly limited, and may be 1000 MPa or less, etc. The measurement of the mechanical strength can be performed by the method described in the examples described later.

[0201] The resin composition layer in the resin sheet with a metal foil of the present invention usually exhibits the characteristic of excellent film flexibility. Therefore, it provides a resin sheet with a metal foil having excellent handleability. Specifically, the resin sheet with a metal foil is cut with a temporary attachment device, and cracks and chips at the cut edge ends are visually confirmed. As a result, there are no cracks or chips in the resin sheet with a metal foil. The evaluation of the film flexibility can be measured by the method described in the examples described later.

[0202] The resin sheet with a metal foil of the present invention usually exhibits the characteristic of excellent flame retardancy of the cured product of the resin composition layer. Therefore, the cured product provides an insulating layer with excellent flame retardancy. The flame retardancy is preferably "V-1", more preferably "V-0" or better, by performing a flame retardancy test according to the UL94 vertical flame retardancy test. The evaluation of the flame retardancy can be measured by the method described in the examples described later.

[0203] The resin sheet with a metal foil of the present invention usually exhibits the property that the cured product of the resin composition layer has a low dielectric loss tangent. Therefore, the cured product provides an insulating layer with a low dielectric loss tangent. The dielectric loss tangent is preferably 0.01 or less, more preferably 0.009 or less, still more preferably 0.008 or less, or 0.005 or less. The lower limit is not particularly limited, and it can be 0.0001 or more, etc. The measurement of the dielectric loss tangent can be carried out according to the method described in the examples below.

[0204] The resin sheet with a metal foil of the present invention usually exhibits the property that the cured product of the resin composition layer has a low dielectric constant. Therefore, the cured product provides an insulating layer with a low dielectric constant. The dielectric constant is preferably 3.5 or less, more preferably 3.4 or less, still more preferably 3.3 or less. The lower limit is not particularly limited, and it can be 0.1 or more, etc. The measurement of the dielectric constant can be carried out according to the method described in the examples below.

[0205] The resin sheet with a metal foil of the present invention can provide a cured product having a high glass transition temperature and excellent film flexibility and mechanical strength. Therefore, the resin sheet with a metal foil of the present invention can be suitably used as a resin sheet (for forming an insulating layer and a conductor layer) for forming both an insulating layer and a conductor layer in the manufacture of a circuit board, and can be suitably used as a resin sheet (for forming an insulating layer and a conductor layer using a vacuum press treatment) for forming both an insulating layer and a conductor layer using a vacuum press treatment in the manufacture of a circuit board, and can be suitably used as a resin sheet (for forming an insulating layer and a conductor layer) for forming both an insulating layer and a conductor layer in the manufacture of a printed wiring board, and can be suitably used as a resin sheet (for forming an insulating layer and a conductor layer using a vacuum press treatment) for forming both an insulating layer and a conductor layer using a vacuum press treatment in the manufacture of a printed wiring board.

[0206] [Circuit Board and Method for Manufacturing the Same] The circuit board of the present invention can be manufactured using the resin sheet with metal foil of the present invention. That is, a circuit board including an insulating layer made of a cured product of the resin composition layer of the resin sheet with metal foil of the present invention and a conductor layer formed from a metal foil can be provided.

[0207] Examples of the circuit board include a printed wiring board, a semiconductor chip package, etc. The circuit board includes an insulating layer made of a cured product of the resin composition layer of the resin sheet with metal foil of the present invention and a conductor layer formed from a metal foil.

[0208] The circuit board can be manufactured, for example, by a method including the following steps (I) and (II) using the above-mentioned resin sheet with metal foil. (I) A step of laminating the resin composition layer in the resin sheet with metal foil on the inner layer substrate by vacuum pressing (II) A step of thermally curing the resin composition layer to form an insulating layer

[0209] The "inner layer substrate" used in step (I) is a member serving as the substrate of the circuit board. Examples include a glass epoxy substrate, a metal substrate, a polyester substrate, a polyimide substrate, a BT resin substrate, a thermosetting polyphenylene ether substrate, etc. Further, the substrate may have a conductor layer on one or both sides thereof, and this conductor layer may be pattern-processed. An inner layer substrate having a conductor layer (circuit) formed on one or both sides of the substrate may be referred to as an "inner layer circuit board". Also, when manufacturing a circuit board, an intermediate product on which an insulating layer and / or a conductor layer is to be further formed is also included in the "inner layer substrate" referred to in the present invention. When the circuit board is a circuit board with built-in components, an inner layer substrate with built-in components can be used.

[0210] The lamination of the inner layer substrate and the resin sheet with metal foil is performed by vacuum pressing after peeling the protective film so that the resin composition layer of the resin sheet with metal foil is laminated to be joined to the inner layer substrate.

[0211] First, peel off the protective film of the resin sheet with a metal foil, and set the inner layer substrate and the resin sheet with a metal foil from which the protective film has been peeled into a vacuum press device so that the resin composition layer of the resin sheet with a metal foil and the inner layer substrate are joined. Next, perform a vacuum press treatment in which the inner layer substrate and the resin composition layer are heat-bonded under reduced pressure conditions.

[0212] The inner layer substrate and the resin sheet with a metal foil from which the protective film has been peeled may be set in the vacuum press device via a cushion paper, a metal plate such as a stainless steel plate (SUS plate), a release film, or the like.

[0213] The vacuum press treatment can be carried out using a conventionally known vacuum press device that presses the resin sheet with a metal foil from which the inner layer substrate and the protective film have been peeled from both sides by a heated metal plate such as a SUS plate. Examples of commercially available vacuum press devices include "VH1-1603" manufactured by Kitakawa Seiki Co., Ltd.

[0214] The vacuum press treatment may be carried out only once, or may be repeated two or more times. When carried out repeatedly two or more times, the crimping pressure, heating temperature, press time, etc. may be the same or different.

[0215] In the vacuum press treatment, the crimping pressure (pressing force) is preferably 5 kgf / cm 2 or more, more preferably 10 kgf / cm 2 or more, still more preferably 15 kgf / cm 2 or more, and preferably 50 kgf / cm 2 or less, more preferably 35 kgf / cm 2 or less, still more preferably 25 kgf / cm 2 or less.

[0216] In the vacuum press treatment, the pressure of the atmosphere, that is, the pressure (degree of vacuum) at the time of decompression in the chamber in which the laminated structure to be treated is stored, is preferably 3 × 10 -2 MPa or less, more preferably 1 × 10 -2 MPa or less. The lower limit is not particularly limited, but 1 × 10-10 It can be, for example, MPa or higher.

[0217] In the vacuum press treatment, the heating temperature varies depending on the composition of the resin composition layer, but is preferably 80°C or higher, more preferably 90°C or higher, and even more preferably 100°C or higher. The upper limit of the heating temperature is not particularly limited, but it can usually be 300°C or lower, for example. Note that the resin composition layer may be thermoset by heating in the vacuum press treatment to form an insulating layer.

[0218] In the vacuum press treatment, the press time is preferably 5 minutes or longer, more preferably 10 minutes or longer, and even more preferably 15 minutes or longer. The upper limit is not particularly limited, but is preferably 300 minutes or shorter, more preferably 200 minutes or shorter, and even more preferably 150 minutes or shorter.

[0219] After laminating a resin sheet with a metal foil from which the protective film has been peeled on the inner layer substrate by vacuum press treatment, in step (II), the resin composition layer is thermoset to form an insulating layer. As a method for thermosetting the resin composition layer, for example, when performing a press treatment by vacuum press treatment, a method of thermosetting the resin composition layer using the heat during pressing to form an insulating layer can be mentioned.

[0220] The thermosetting conditions of the resin composition layer are not particularly limited, and the conditions usually employed when forming the insulating layer of the circuit board and the printed wiring board may be used.

[0221] For example, the thermosetting conditions of the resin composition layer vary depending on the type of the resin composition layer and the like, but 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 can be preferably 5 minutes to 120 minutes, more preferably 10 minutes to 100 minutes, and even more preferably 15 minutes to 100 minutes.

[0222] Before thermosetting the resin composition layer, the resin composition layer may be preheated at a temperature lower than the curing temperature. For example, prior to thermosetting the resin composition layer, the resin composition layer may be preheated at a temperature of 50°C or higher and less than 120°C (preferably 60°C or higher and 115°C or lower, more preferably 70°C or higher and 110°C or lower) for 5 minutes or longer (preferably 5 minutes to 150 minutes, more preferably 15 minutes to 120 minutes, still more preferably 15 minutes to 100 minutes).

[0223] Since the resin sheet with a metal foil used in the present invention contains a metal foil, as step (III), it may include a step of forming a conductor layer (circuit) by a subtractive method or a modified semi-additive method.

[0224] In step (III), a conductor layer can be formed by a subtractive method or a modified semi-additive method using the metal foil in the resin sheet with a metal foil.

[0225] In the subtractive method, unnecessary portions (non-circuit forming portions) of the metal foil are selectively removed by etching or the like to form a circuit. Circuit formation by the subtractive method may be carried out according to a known procedure. For example, circuit formation by the subtractive method can be carried out by a method including: i) providing an etching resist on the surface of the metal foil (i.e., the surface opposite to the surface joined to the resin composition layer); ii) exposing and developing the etching resist to form a wiring pattern; iii) etching and removing the exposed metal foil portion; and iv) removing the etching resist.

[0226] In the modified semi-additive method, the non-circuit forming portion of the metal foil is protected by a plating resist, and after thickening the circuit forming portion with a metal such as copper by electrolytic plating, the plating resist is removed, and the metal foil other than the circuit forming portion is removed by etching to form a circuit. Circuit formation by the modified semi-additive method may be carried out according to a known procedure. For example, circuit formation by the modified semi-additive method may be carried out by a method including: i) providing a plating resist on the surface of the metal foil (i.e., the surface opposite to the surface joined to the resin composition layer); ii) exposing and developing the plating resist to form a wiring pattern; iii) performing electrolytic plating through the plating resist; iv) removing the plating resist; and v) etching and removing the metal foil other than the circuit forming portion. When the metal foil is thick, before the above i), the entire surface of the metal foil may be thinned by etching or the like so that the metal foil has a desired thickness (usually 5 μm or less, 4 μm or less, or 3 μm or less).

[0227] When manufacturing a circuit board, a step of (IV) drilling and a step of (V) roughening the insulating layer may be further carried out. These steps (IV) to (V) may be carried out according to various methods known to those skilled in the art used for manufacturing a circuit board. Further, if necessary, the formation of the insulating layer and the conductor layer in steps (I) to (V) may be repeated to form a multilayer wiring board.

[0228] [Semiconductor device] The semiconductor device of the present invention includes the circuit board of the present invention. The semiconductor device of the present invention can be manufactured using the circuit board of the present invention.

[0229] Examples of the semiconductor device include various semiconductor devices used in electrical products (e.g., computers, mobile phones, digital cameras, and televisions, etc.) and vehicles (e.g., motorcycles, automobiles, trains, ships, and airplanes, etc.).

[0230] The semiconductor device of the present invention can be manufactured by mounting components (semiconductor chips) on the conductive portions of a circuit board. The "conductive portion" refers to "a portion that transmits an electrical signal in the circuit board", and the location thereof may be either the surface or an embedded portion. Further, the semiconductor chip is not particularly limited as long as it is an electric circuit element made of a semiconductor.

[0231] The method for mounting a semiconductor chip when manufacturing a semiconductor device is not particularly limited as long as the semiconductor chip functions effectively. Specifically, examples include a wire bonding mounting method, a flip chip mounting method, a mounting method using a bump-less build-up layer (BBUL), a mounting method using an anisotropic conductive film (ACF), a mounting method using a non-conductive film (NCF), and the like. Here, the "mounting method using a bump-less build-up layer (BBUL)" refers to "a mounting method in which a semiconductor chip is directly embedded in a recess of a circuit board and the semiconductor chip is connected to wiring on the circuit board".

Example

[0232] Hereinafter, the present invention will be specifically described with reference to examples. The present invention is not limited to these examples. In the following, "parts" and "%" mean "parts by mass" and "mass%", respectively, unless otherwise specified.

[0233] <Synthesis Example 1: Synthesis of Polyimide Resin 1> Into a 500-ml separable flask equipped with a nitrogen inlet tube and a stirring device, 9.13 g (30 mmol) of 4-amino-benzoic acid 5-amino-1,1'-biphenyl-2-yl (compound of formula (A-3)), 15.61 g (30 mmol) of 4,4'-(4,4'-isopropylidenediphenoxy) bisphthalic dianhydride, 94.64 g of N-methyl-2-pyrrolidone, 0.47 g (6 mmol) of pyridine, and 10 g of toluene were added. Under a nitrogen atmosphere, the reaction was carried out at 180 °C for 4 hours while removing toluene out of the system during the reaction, to obtain a polyimide solution (non-volatile content: 20%) containing a polyimide resin. No precipitation of the synthesized polyimide resin 1 was observed in the polyimide solution. The weight-average molecular weight of the polyimide resin 1 was 10,000.

[0234] <Synthesis Example 2: Synthesis of Polyimide Resin 2> Into a 1000-ml separable flask equipped with a nitrogen inlet tube and a stirring device, 62.46 g (120 mmol) of 4,4'-(4,4'-isopropylidenediphenoxy) bisphthalic dianhydride (BPADA), 12.17 g (40 mmol) of (5-amino-2-biphenyl)-4-aminobenzoate (PHBAAB), 27.56 g (80 mmol) of 4,4'-(m-phenylenediisopropylidene) dianiline (Bisaniline-M), 303 g of N-methylpyrrolidone (NMP), 1.90 g (24 mmol) of pyridine, and 34 g of toluene were added. Under a nitrogen atmosphere, the reaction was carried out at 180 °C for 10 hours while removing toluene out of the system during the reaction, to obtain a 25% by mass polyimide solution. The weight-average molecular weight of the polyimide resin 2 was 50,000.

[0235] <Synthesis Example 3: Synthesis of Polyimide Resin 3> Into a reaction vessel equipped with a stirrer, a water separator, a thermometer, and a nitrogen gas inlet tube, 65.0 g of a commercially available aromatic tetracarboxylic dianhydride ("BisDA-1000" manufactured by SABIC), 266.5 g of cyclohexanone, and 44.4 g of methylcyclohexane were charged, and the solution was heated to 60°C. Next, 43.7 g of a commercially available dimer diamine ("PRIAMINE 1075" manufactured by Clariant Japan) and 5.4 g of 1,3-bisaminomethylcyclohexane were added dropwise, and then imidization reaction was carried out at 140°C for 1 hour. Thereby, a polyimide solution (non-volatile content 30%) containing a dimer diamine polyimide resin was obtained. The weight average molecular weight of the polyimide resin 3 was 25000.

[0236] <Production of resin varnish> Each component was weighed in the number of parts by mass shown in the following table, and further 10 parts of methyl ethyl ketone (MEK) and 10 parts of cyclohexanone were mixed and uniformly dispersed using a high-speed rotating mixer to obtain a resin varnish.

Table 1

[0237] Details of each component described in the table are as follows. (A) Polyimide resin · Polyimide 1: Polyimide resin synthesized in Synthesis Example 1 · Polyimide 2: Polyimide resin synthesized in Synthesis Example 2 · Polyimide 3: Polyimide resin synthesized in Synthesis Example 3 (B) Phenoxy resin · YX7553BH30: Phenoxy resin, 1:1 solution of MEK and cyclohexanone with a non-volatile content of 30% by mass, weight average molecular weight 35000, manufactured by Mitsubishi Chemical Corporation · YL7891BH30: Phenoxy resin, 1:1 solution of MEK and cyclohexanone with a non-volatile content of 30% by mass, weight average molecular weight 26000, manufactured by Mitsubishi Chemical Corporation · YX7200B35: Phenoxy resin, MEK solution with a non-volatile content of 30% by mass, weight-average molecular weight of 10,000, manufactured by Mitsubishi Chemical Corporation (C) Inorganic filler · SO-C2: Spherical silica surface-treated with an amine-based alkoxysilane compound ("KBM573" manufactured by Shin-Etsu Chemical Co., Ltd.), average particle size of 0.5 μm, specific surface area of 5.8 m 2 / g, manufactured by Admatechs Co., Ltd. · UFP-30: Spherical silica surface-treated with an amine-based alkoxysilane compound ("KBM573" manufactured by Shin-Etsu Chemical Co., Ltd.), average particle size of 0.3 μm, specific surface area of 5.8 m 2 / g, manufactured by Denka Co., Ltd. (D) Thermosetting resin · YX4000HK: Bixylenol-type epoxy resin, epoxy equivalent of 194 g / eq., manufactured by Mitsubishi Chemical Corporation · NC-3000-L: Biphenyl-type epoxy resin, epoxy equivalent of 269 g / eq., manufactured by Nippon Kayaku Co., Ltd. · ZX-1059: A 1:1 mixture of bisphenol A-type epoxy resin and bisphenol F-type epoxy resin, epoxy equivalent of 169 g / eq., manufactured by Nippon Steel Chemical & Material Co., Ltd. · 630: Aminophenol-type epoxy compound, epoxy equivalent of 98 g / eq., manufactured by Mitsubishi Chemical Corporation · HPC-8000-65T: Active ester resin containing a dicyclopentadiene-type diphenol structure, functional group equivalent of 223 g / eq., toluene solution with a non-volatile content of 65% by mass, manufactured by DIC Corporation · LA-7054: Phenolic curing agent having a triazine skeleton and a phenol novolac structure, functional group equivalent of 125 g / eq., MEK solution with a non-volatile content of 60% by mass, manufactured by DIC Corporation · SN-485: Naphthol-type phenolic curing agent, functional group equivalent of 205 g / eq., manufactured by Nippon Steel Chemical & Material Co., Ltd. · MIR-3000-70MT: Maleimide compound containing an aromatic ring skeleton, functional group equivalent of 275 g / eq., 1:1 solution of MEK and toluene with a non-volatile content of 70% by mass, manufactured by Nippon Kayaku Co., Ltd. · V03: Carbodiimide-based curing agent, functional group equivalent of 216, toluene solution with a non-volatile content of 50% by mass, manufactured by Nisshinbo Chemical Inc. ·ODA-BOZ: Benzoxazine compound, functional group equivalent weight 218 g / eq., manufactured by JFE Chemical (E) Thermoplastic resin ·FPC-0220: Polycarbonate resin, viscosity average molecular weight 20,000, manufactured by Mitsubishi Gas Chemical Company ·AC3816N: Stafiloid, manufactured by Aika Industries (F) Flame retardant ·FP-100: Phosphorus-based flame retardant, manufactured by Fushimi Pharmaceutical ·HCA-HQ-HST: Phosphorus-based flame retardant, manufactured by Sanko Chemical Industries (G) Curing accelerator ·DMAP: Manufactured by Tokyo Chemical Industry ·1B2PZ: Manufactured by Shikoku Chemicals

[0238] <Fabrication of resin sheet with metal foil> The resin varnishes obtained in the examples and comparative examples were applied onto the release surface of a polyethylene terephthalate film with release treatment (Toray Industries, Inc.'s "Lumirror R80, thickness 38 μm") which served as a support, using a die coater so that the thickness of the resin composition layer became 40 μm, and dried at 80 to 120 °C (average 100 °C) for 5 minutes. Subsequently, a copper foil with carrier (Mitsui Mining & Smelting Co., Ltd.'s "Micro Shin MT18Ex", 3-μm-thick ultra-thin copper foil / 18-μm-thick carrier copper foil) equipped with a carrier copper foil and an ultra-thin copper foil was laminated using a roll laminator (manufactured by Daising Lamicator Co., Ltd., "FIRST LAMINATOR VA-770H") at a roll pressure of 0.25 MPa, a feed rate of 0.3 m / min, and a roll temperature of 90 °C to obtain a resin sheet with metal foil.

[0239] <Evaluation of film flexibility> The resin sheet with metal foil was cut with a temporary fixing device, and cracks and chips at the cut edge ends were visually confirmed. Then, based on the following evaluation criteria, resin chipping was evaluated. 〇: There are no cracks or chips in the resin sheet with metal foil. ×: There are cracks or chips in the resin sheet with metal foil.

[0240] <Fabrication of cured product for evaluation by vacuum press curing> From the resin sheet with metal foil, the support was peeled off, and it was overlapped so that another copper foil ( "Micro Shin MT18Ex" manufactured by Mitsui Mining & Smelting Co., Ltd.) was in contact with the resin composition layer. Using a vacuum press machine (VH1-1603 manufactured by Kitakawa Seiki Co., Ltd.), the degree of vacuum during pressing was 1×10 -3 MPa or less, and the pressure condition was 20 kgf / cm 2 and as the heating condition, for the first stage of pressing, the temperature was 100°C and the time was 30 minutes, and for the second stage of pressing, the temperature was 190°C and the time was 120 minutes to thermally cure the resin composition layer. The thermally cured resin sheet with metal foil was immersed in an aqueous solution of iron(II) chloride (manufactured by Tsurumi Soda Co., Ltd., Baumé degree 40), and after removing the copper foil, it was dried at 130°C for 15 minutes to obtain a sheet-like cured product. The obtained cured product was referred to as "Cured product for evaluation by vacuum press curing".

[0241] <Measurement of dielectric constant and dielectric loss tangent> The cured product for evaluation by vacuum press curing was cut into test pieces with a width of 2 mm and a length of 80 mm. For the test pieces, using "HP8362B" manufactured by Agilent Technologies, the dielectric loss tangent was measured at a measurement frequency of 5.8 GHz and a measurement temperature of 23°C by the cavity resonance perturbation method. Measurements were performed on two test pieces and the average value was calculated.

[0242] <Measurement of glass transition temperature> The cured product for evaluation by vacuum press curing was cut into test pieces with a width of 2 mm and a length of 80 mm. For the test pieces, they were cut into test pieces with a width of about 5 mm and a length of about 15 mm, and thermomechanical analysis was performed by the tensile loading method using a dynamic viscoelasticity measuring device (EXSTAR6000, manufactured by SII NanoTechnology Inc.). After mounting the test pieces on the device, measurements were performed under the measurement conditions of a load of 200 mN and a heating rate of 2°C / min. The peak top of the obtained tanδ was calculated as the glass transition temperature (°C) and evaluated according to the following criteria. 〇: 160°C or higher. △: 150°C or higher and less than 160°C ×: Less than 150°C

[0243] <Measurement of mechanical strength> The cured product for evaluation by vacuum press curing was cut into test pieces with a width of 2 mm and a length of 80 mm. For these test pieces, Agilent Technologies measured the tensile strength using a tensile testing machine "RTC-1250A" manufactured by Orientec Co., Ltd., and measured the mechanical strength at 23°C. The measurement was carried out in accordance with JIS K7127. The measurement was performed 5 times, and the average value of the top 3 points was calculated and evaluated according to the following criteria. 〇: 115 MPa or more. △: 100 MPa or more and less than 115 MPa. ×: Less than 100 MPa.

[0244] <Evaluation of Flame Retardancy> In the same procedure as the resin sheet with a metal foil having a resin composition layer thickness of 40 μm, a resin sheet with a metal foil having a resin composition layer thickness of 90 μm was produced. The support of this resin sheet with a metal foil was peeled off, and it was overlaid on both sides of a substrate obtained by etching and removing the copper foil of a copper-clad laminate (Resona Co., Ltd. "MCL-E-700G") with a substrate thickness of 0.2 mm. Using a vacuum press machine (VH1-1603 manufactured by Kitakawa Seiki Co., Ltd.), the degree of vacuum during pressing was 1×10 -3 MPa or less, and the pressure condition was 20 kgf / cm 2 And as the heating condition, the first stage of pressing was at a temperature of 100°C for 30 minutes, and the second stage of pressing was at a temperature of 190°C for 120 minutes to thermally cure the resin composition layer. The thermally cured resin with a metal foil was immersed in an aqueous solution of iron(II) chloride (manufactured by Tsurumi Soda Co., Ltd., Baumé degree 40), and after removing the copper foil, it was dried at 130°C for 15 minutes to obtain a sample for the flame retardancy test. The sample for the flame retardancy test was cut into a width of 12.7 mm and a length of 127 mm, and the cut surface was polished with a polishing machine (RotoPol-22 manufactured by Struers). Taking 5 such samples as a set, a flame retardancy test was carried out according to the UL94 vertical flame retardancy test and evaluated according to the following criteria. 〇: The evaluation result of the UL94 vertical flame retardancy test is V-0. △: The evaluation result of the UL94 vertical flame retardancy test is V-1. ×: The evaluation result of the UL94 vertical flame retardancy test is other than V-0 and V-1.

[0245]

Table 2

[0246] Examples 1 to 9 are excellent in film flexibility, and it can be seen that even when an insulating layer is formed by vacuum press treatment, the glass transition temperature (Tg), film flexibility, mechanical strength, flame retardancy, dielectric tangent, and dielectric constant of the insulating layer are excellent.

[0247] In contrast, in Comparative Example 1, since it does not contain a polyimide resin, the glass transition temperature after vacuum press treatment is low, and it can be seen that the mechanical strength and flame retardancy are inferior to those of Examples 1 to 9. In Comparative Examples 2 and 4, since they do not contain a phenoxy resin, it can be seen that either the film flexibility or the mechanical strength is inferior to those of Examples 1 to 9. Further, in Comparative Example 3, since it does not contain a polyimide resin and a phenoxy resin, the resin varnish is repelled even when trying to apply the resin varnish on the support, and the resin composition layer cannot be formed into a film, and the glass transition temperature and the like cannot be measured. Also, in Comparative Examples 5 and 6 where a1 / b1 is outside the range of 0.05 or more and 50 or less, it can be seen that either the mechanical strength or the film flexibility is inferior to those of Examples 1 to 9.

Claims

1. A resin sheet with a metal foil, comprising a metal foil, a resin composition layer, and a protective film in this order, The resin composition layer contains (A) a polyimide resin, (B) a phenoxy resin, and (C) an inorganic filler, A resin sheet with a metal foil, wherein a1 / b1 is 0.05 or more and 50 or less, where a1 is the content of the (A) component when the resin component in the resin composition layer is 100% by mass, and b1 is the content of the (B) component when the resin component in the resin composition layer is 100% by mass.

2. The resin sheet with a metal foil according to claim 1 , wherein the component (A) has an ester bond.

3. The resin sheet with a metal foil according to claim 1 , further comprising (G) a flame retardant.

4. 2. The resin sheet with a metal foil according to claim 1, wherein a2 / b2 is 0.01 or more and 10 or less, where a2 is the weighted average molecular weight of the component (A) and b2 is the weighted average molecular weight of the component (B).

5. The resin sheet with a metal foil according to claim 1 , further comprising (D) a thermosetting resin.

6. 2. The resin sheet with a metal foil according to claim 1, which is used for forming an insulating layer and a conductor layer using a vacuum press treatment.

7. The resin sheet with a metal foil according to claim 1 , wherein the metal foil is a copper foil.

8. A circuit board comprising: an insulating layer formed from a cured product of a resin composition layer of the resin sheet with a metal foil according to any one of claims 1 to 7; and a conductor layer formed from the metal foil of the resin sheet with a metal foil according to any one of claims 1 to 7.

9. A semiconductor device comprising the circuit board according to claim 8.

10. (I) a step of laminating a resin composition layer of the resin sheet with a metal foil according to any one of claims 1 to 7 on an inner layer substrate by vacuum pressing; and (II) a step of thermally curing the resin composition layer to form an insulating layer.

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