Resin sheet with metal foil

Abstract

The present invention addresses the problem of providing, for example, a resin sheet with a metal foil, which is capable of obtaining a cured product having a high glass transition temperature and excellent film flexibility. [Solution] A metal foil-attached resin sheet provided with a metal foil, a resin composition layer, and a protective film in this order, the resin composition layer containing (A) an organic solvent, (B) a thermosetting resin, and (C) an inorganic filler, the component (A) containing (A-1) an organic solvent having a boiling point of 180 DEG C or more, the component (B) containing (A-2) an organic solvent having a boiling point of 180 DEG C or more, and the component (C) containing (A-3) an organic solvent having a boiling point of 180 DEG C or more, and the component (C) containing (A-3) an organic solvent having a boiling point of 180 DEG C or more. The content of the component (A-1) is 20% by mass or more when the total amount of the component (A) contained in the resin composition layer is 100% by mass.

Description

Technical Field

[0001] The present invention relates to a resin sheet with a metal foil. Furthermore, 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 resin having excellent heat resistance and insulation properties has been used in an insulating layer such as a circuit board (see, for example, Patent Documents 1 and 2).

[0003] Prior Art Documents Patent Documents Patent Document 1: Japanese Unexamined Patent Application Publication No. 2020-66694 Patent Document 2: Japanese Patent No. 6240798 Summary of the Invention

[0004] Technical Problem to be Solved by the Invention In recent years, as a method for forming a conductor layer on an insulating layer, a resin sheet with a metal foil is used. At this time, 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, a vacuum pressing process (vacuum hot pressing process) of the inner layer substrate and the resin sheet with a metal foil is performed in such a manner that the resin composition layer is bonded to the inner layer substrate. Since the resin composition layer is thermally cured during the vacuum pressing process, 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, the resin composition layer is formed in a state of being sandwiched between the inner layer substrate and the metal foil during the vacuum pressing process. Therefore, when the resin composition layer is thermally cured, the organic solvent contained in the resin composition layer cannot be smoothly removed from the resin composition layer. Therefore, the curing of the resin composition layer may not be sufficient, and the glass transition temperature of the insulating layer becomes low.

[0006] In order to sufficiently cure the resin composition layer, a method of reducing the amount of the organic solvent contained in the resin composition layer can be considered. However, if the amount of the organic solvent is reduced, the flexibility of the resin composition layer is impaired, and cracks or notches sometimes occur in the resin composition layer of the resin sheet with a metal foil. Hereinafter, the property that the resin composition layer has high flexibility and can suppress cracks and notches in the resin composition layer is sometimes referred to as "film flexibility".

[0007] Thus, the present inventors have found a new problem that the glass transition temperature of the cured product of the resin composition layer is low and the film flexibility is poor when an insulating layer is formed by a vacuum pressing process using a resin sheet with a metal foil.

[0008] The present invention has been made in view of the above problems, and therefore an object of the present invention is to provide: a resin sheet with a metal foil capable of obtaining a cured product having a high glass transition temperature and excellent film flexibility; 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.

[0009] Means for Solving Technical Problems The inventors of the present invention conducted intensive research and found that: a resin sheet with a metal foil sequentially including a metal foil, a resin composition layer, and a protective film, the resin composition layer contains (B) a thermosetting resin and (C) an inorganic filler, and by containing a specific amount of (A-1) an organic solvent having a boiling point of 180°C or higher, a cured product having a high glass transition temperature and excellent film flexibility can be obtained, thereby completing the present invention.

[0010] That is, the present invention includes the following content. [1] A resin sheet with a metal foil, which is a resin sheet with a metal foil sequentially including a metal foil, a resin composition layer, and a protective film, the resin composition layer contains (A) an organic solvent, (B) a thermosetting resin, and (C) an inorganic filler, the (A) component contains (A-1) an organic solvent having a boiling point of 180°C or higher, and when the total amount of the (A) component contained in the resin composition layer is set to 100% by mass, the content of the (A-1) component is 20% by mass or more. [2] The resin sheet with a metal foil according to [1], further including (D) a flexible resin. [3] The resin sheet with a metal foil according to [2], wherein the (D) component contains a polyimide resin. [4] The resin sheet with a metal foil according to [2] or [3], wherein when the content of the (A-1) component contained in the resin composition layer is set to a1 and the content of the (D) component contained in the resin composition layer is set to d1, a1 / d1 is 0.1 or more and 25 or less. [5] The resin sheet with a metal foil according to any one of [1] to [4], wherein the boiling point of the (A-1) component is 250°C or lower. [6] The resin sheet with a metal foil according to any one of [1] to [5], wherein the (A-1) component contains any one of a carbon-oxygen double bond and a carbon-sulfur double bond. [7] The resin sheet with a metal foil according to any one of [1] to [6], wherein the (A-1) component contains a lactam-based organic solvent. [8] The resin sheet with a metal foil according to any one of [1] to [7], wherein the (A-1) component contains γ-butyrolactone. [9] The resin sheet with a metal foil according to any one of [1] to [8] is used to form an insulating layer and a conductor layer by vacuum pressing treatment.

[10] The resin sheet with a metal foil according to any one of [1] to [9], wherein the metal foil is a copper foil.

[11] A circuit board, comprising: An insulating layer formed by curing a resin composition layer of the resin sheet with a metal foil according to any one of [1] to

[10] , and A conductor layer formed by the metal foil of the resin sheet with a metal foil according to any one of [1] to

[10] .

[12] A semiconductor device, comprising the circuit board described in

[11] .

[13] A method for manufacturing a circuit board, the manufacturing method comprising: (I) A step of laminating the resin composition layer in the resin sheet with a metal foil according to any one of [1] to

[10] on an inner layer substrate by vacuum pressing treatment, and (II) A step of thermally curing the resin composition layer to form an insulating layer. Effects of the Invention

[0011] According to the present invention, it is possible to provide: a resin sheet with a metal foil capable of obtaining a cured product having a high glass transition temperature and excellent film flexibility; 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. Detailed Embodiments

[0011] Hereinafter, embodiments and examples are shown to describe the present invention in detail. However, the present invention is not limited to the following-described embodiments and examples, and can be arbitrarily modified and implemented within the scope of the claims of the present invention and their equivalents.

[0012] [Resin Sheet with a Metal Foil] The resin sheet with a metal foil of the present invention is a resin sheet with a metal foil sequentially having a metal foil, a resin composition layer, and a protective film. The resin composition layer contains (A) an organic solvent, (B) a thermosetting resin, and (C) an inorganic filler. The (A) component contains (A-1) an organic solvent having a boiling point of 180 °C or higher, and the content of the (A-1) component is 20% by mass or more when the total amount of the (A) component contained in the resin composition layer is set to 100% by mass. Such a resin sheet with a metal foil can obtain a cured product having a high glass transition temperature and excellent film flexibility. In addition, a cured product having excellent tackiness, a low dielectric loss tangent, and excellent elongation at break can generally be obtained from the resin sheet with a metal foil.

[0014] <Metal foil> The resin sheet with a metal foil of the present invention has a metal foil. The conductor layer of the circuit board can also be formed of a metal foil. At this time, the conductor layer can be formed of the whole of the metal foil or a part of the metal foil.

[0015] Examples of the metal foil include a copper foil, an aluminum foil, etc., and a copper foil is preferred. As the copper foil, a foil formed of single metal of copper or a foil formed of an alloy of copper and other metals (such as tin, chromium, silver, magnesium, nickel, zirconium, silicon, titanium, etc.) can be used.

[0016] The metal foil can be a single-layer structure or a multilayer structure in which two or more single metal layers or alloy layers formed of different kinds of metals or alloys are laminated. Examples of the metal foil of the multilayer structure include a metal foil including a carrier metal foil and an extremely thin metal foil joined to the carrier metal foil. The metal foil of the multilayer structure may also include a release layer between the carrier metal foil and the extremely thin metal foil that enables the extremely thin metal foil to be peeled off from the carrier metal foil. For the release layer, as long as the extremely thin metal foil can be peeled off from the carrier metal foil, there is no particular limitation, and examples thereof include an alloy layer of an element selected from Cr, Ni, Co, Fe, Mo, Ti, W, and P; an organic film, etc. It should be noted that when using a metal foil of a multilayer structure, the resin composition layer is provided on the extremely thin metal foil.

[0017] 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 further preferably 2 μm or more. The upper limit is not particularly limited, and it is preferably 35 μm or less, more preferably 25 μm or less, and further preferably 15 μm or less. In the case where the metal foil is a multilayer structure, it is preferred that the thickness of the whole metal foil is in the above range, and the thickness of the extremely thin metal foil can be, for example, in the range of 0.1 μm or more and 10 μm or less.

[0018] The arithmetic mean roughness (Ra) of the surface of the metal foil that is joined to the resin composition layer is preferably 300 nm or more, preferably 350 nm or more, more preferably 400 nm or more, and further preferably 500 nm or more from the viewpoint of improving the adhesion to the resin composition layer. The upper limit is not particularly limited, and it is preferably 1000 nm or less, more preferably 900 nm or less, and further preferably 800 nm or less. The arithmetic mean roughness (Ra) is a value measured based on ISO 25178, and a non-contact surface roughness meter can be used for measurement. Examples of the non-contact surface roughness meter include "WYKO NT3300" manufactured by VEECO INSTRUMENTS.

[0019] The metal foil can be a commercially available product. Examples of commercially available metal foils include "Micro Thin MT18Ex", "Micro Thin 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 Co., Ltd., "CF-TX4-SV", "V9", "HD", "FLEQ HD", "FUTF", "RCF-T4X", "RCF-T5B", etc. manufactured by Fukuda Metal Foil Powder Industry Co., Ltd.

[0020] As a method for manufacturing the metal foil, it can be manufactured by known methods such as the electrolytic method and the rolling method, for example.

[0021] <Resin composition layer> The resin sheet with a metal foil has a resin composition layer. An insulating layer can be formed by thermally curing the resin composition layer. Generally, the insulating layer contains the cured product of the resin composition layer, and preferably contains only the cured product of the resin composition layer. The resin composition layer is usually a single-layer structure, but may also be a structure of two or more layers as long as the effects of the present invention are not hindered.

[0022] The resin composition layer contains (A-1) an organic solvent having a boiling point of 180°C or higher as (A) an organic solvent, (B) a thermosetting resin, and (C) an inorganic filler. Additionally, as needed, the resin composition layer can contain (A-2) an organic solvent having a boiling point less than 180°C, (D) a flexible resin, (E) a phenoxy resin, (F) a flame retardant, (G) a curing accelerator, and (H) other additives.

[0023] 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 set to 100% by mass. Additionally, in the present invention, the non-volatile components refer to the entire components after removing the solvent from the resin composition layer. Further, in the present invention, the resin component in the resin composition layer refers to the components after removing (C) the inorganic filler from the non-volatile components of the resin composition layer.

[0024] In the present invention, unless otherwise stated, the boiling point refers to the boiling point at atmospheric pressure (760 mmHg).

[0025] -(A) Organic solvent- The resin composition layer contains (A) an organic solvent as component (A). The (A) organic solvent includes (A-1) an organic solvent having a boiling point of 180°C or higher, and when the total amount of component (A) contained in the resin composition layer is 100% by mass, the content of component (A-1) is 20% by mass or more. By containing a specific amount of component (A-1) in the resin composition layer, a cured product with a high glass transition temperature and excellent film flexibility can be obtained.

[0026] As needed, in addition to component (A-1), component (A) may further contain (A-2) an organic solvent having a boiling point of less than 180°C. Component (A-1) and component (A-2) can be used individually as one kind, or two or more kinds can be used in combination.

[0027] ((A-1) organic solvent having a boiling point of 180°C or higher) The resin composition layer contains (A-1) an organic solvent having a boiling point of 180°C or higher as component (A-1), and when the total amount of component (A) contained in the resin composition layer is 100% by mass, the content of component (A-1) is 20% by mass or more. By containing a specific amount of component (A-1) in the resin composition layer, a cured product with a high glass transition temperature, excellent mechanical strength and film flexibility can be obtained.

[0028] When the total amount of component (A) contained in the resin composition layer is 100% by mass, the content of component (A-1) (residual solvent amount) is 20% by mass or more, preferably 25% by mass or more, more preferably 30% by mass or more, further preferably 35% by mass or more, 40% by mass or more, 45% by mass or more, 50% by mass or more, 55% by mass or more. The upper limit is preferably 100% by mass or less, more preferably 95% by mass or less, further preferably 90% by mass or less, 85% by mass or less, 80% by mass or less. By adjusting the content of component (A-1) within the above range, component (A-1) is contained in the resin composition layer, and thus a cured product with a high glass transition temperature and excellent film flexibility can be obtained. The content of component (A-1) represents the residual solvent amount contained in the resin composition layer of the resin sheet with a metal foil. The residual solvent amount can be measured by the method described in the following examples.

[0029] The boiling point of component (A-1) is 180°C or higher, preferably 185°C or higher, more preferably 190°C or higher, further preferably 195°C or higher, 200°C or higher. The upper limit is preferably 250°C or lower, more preferably 230°C or lower, further preferably 220°C or lower.

[0030] (Component (A-1) may include a non-aromatic solvent that does not contain an aromatic ring in the molecule and an aromatic solvent that contains an aromatic ring in the molecule. Among them, from the viewpoint of further improving the glass transition temperature and the flexibility of the film, component (A-1) is preferably a non-aromatic solvent.)

[0031] From the viewpoint of increasing the glass transition temperature and enhancing the mechanical strength, component (A-1) preferably contains either a carbon-oxygen double bond (C=O) or a carbon-sulfur double bond (S=O).

[0032] (Component (A-1) preferably has a cyclic structure, and more preferably has either a lactam structure or a lactone structure.)

[0033] Specific examples of component (A-1) include, for example: organic solvents containing a sulfur atom such as dimethyl sulfoxide (DMSO); lactone-based organic solvents such as γ-butyrolactone (GBL) and δ-valerolactone; lactam-based organic solvents such as N-methylpyrrolidone (NMP); aromatic hydrocarbon-based organic solvents such as tetramethylbenzene; glycol ether-based organic solvents such as methyl carbitol, butyl carbitol, and dipropylene glycol monoethyl ether; ester-based organic solvents such as butyl cellosolve acetate, carbitol acetate, and ethyldiglycol acetate; petroleum-based organic solvents such as petroleum ether, petroleum naphtha, hydrogenated petroleum naphtha, solvent naphtha, and Ipzole 150. Among them, as component (A-1), it is preferably to contain any one of an organic solvent containing a sulfur atom, a lactone-based organic solvent, and a lactam-based organic solvent, and more preferably to contain a lactone-based organic solvent. Among the lactone-based organic solvents, γ-butyrolactone is preferred.)

[0034] When the non-volatile components contained in the resin varnish are set to 100% by mass, the content of component (A-1) is preferably 5% by mass or more, more preferably 5.5% by mass or more, and further preferably 6% by mass or more. The upper limit is preferably 10% by mass or less, more preferably 8% by mass or less, and further preferably 7% by mass or less. As described above, the non-volatile components refer to the entire components after removing the solvent from the resin composition layer.)

[0035] When all the components contained in the resin composition layer are set to 100% by mass, the content of component (A-1) (the residual solvent amount of component (A-1)) is preferably 0.5% by mass or more, more preferably 1% by mass or more, further preferably 3% by mass or more, preferably 20% by mass or less, more preferably 18% by mass or less, further preferably 15% by mass or less, and 10% by mass or less.)

[0036] ((Organic solvent with a boiling point less than 180 °C) (A-2)) The resin composition layer may contain an organic solvent (A-2) with a boiling point of less than 180°C as an optional volatile component. Component (A-2) may be used alone as one kind, or two or more kinds may be used in combination.

[0037] The boiling point of component (A-2) is less than 180°C, preferably 170°C or lower, more preferably 165°C or lower, and further preferably 160°C or lower. The lower limit is preferably 40°C or higher, more preferably 50°C or higher, and further preferably 60°C or higher.

[0038] Specific examples of component (A-2) include, for example, ketone solvents such as ethyl methyl ketone (MEK) and cyclohexanone; aromatic hydrocarbon solvents such as toluene and xylene; glycol ether solvents such as methyl cellosolve, butyl cellosolve, dipropylene glycol diethyl ether, triethylene glycol monoethyl ether, and propylene glycol monomethyl ether; ester solvents such as ethyl acetate and butyl acetate; ether ester solvents such as propylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, carbitol acetate, and methyl methoxypropionate; amide solvents such as N,N-dimethylacetamide; aliphatic hydrocarbon solvents such as octane and decane; and petroleum solvents such as petroleum ether, petroleum naphtha, hydrogenated petroleum naphtha, and solvent naphtha.

[0039] When the total amount of component (A) contained in the resin composition layer is set to 100% by mass, the content of component (A-2) (residual solvent amount of component (A-2)) is preferably 50% by mass or less, more preferably 45% by mass or less, further preferably 40% by mass or less, 35% by mass or less, preferably 0% by mass or more than 0% by mass, more preferably more than 0% by mass, further preferably 5% by mass or more, and 10% by mass or more. The residual solvent amount can be measured by the method described in the examples below.

[0040] When the total amount of all components contained in the resin composition layer is set to 100% by mass, the content of component (A-2) (residual solvent amount of component (A-2)) is preferably 3% by mass or less, more preferably 2% by mass or less, and further preferably 1% by mass or less. The lower limit is not particularly limited and may be 0.01% by mass or more, etc.

[0041] When the total amount of all components contained in the resin composition layer is set to 100% by mass, the content of component (A) (total content of component (A-1) and component (A-2) (total residual solvent amount)) is preferably 1% by mass or more, more preferably 2% by mass or more, further preferably 4% by mass or more, preferably 20% by mass or less, more preferably 18% by mass or less, further preferably 15% by mass or less, and 10% by mass or less.

[0042] -(B) Thermosetting resin- The resin composition layer contains a (B) thermosetting resin as the component (B). The (B) thermosetting resin as the component (B) does not include the substances belonging to the component (A). The type of the (B) thermosetting resin is not particularly limited as long as it can be cured by heat. The (B) thermosetting resin can be used alone as one kind, or two or more kinds can be used in combination.

[0043] Examples of the (B) thermosetting resin include epoxy resins, polyphenylene ether resins, free-radical polymerizable resins, phenolic resins, cyanate ester resins, active ester resins, carbodiimide resins, acid anhydride resins, amine resins, benzoxazine resins, and thiol resins. The thermosetting resin can be used alone as one kind, or two or more kinds can be used in combination.

[0044] From the viewpoint of significantly obtaining the effects of the present invention, the (B) thermosetting resin is preferably used in combination with an epoxy resin and a resin capable of reacting with the epoxy resin to cure the resin composition layer. The resin capable of reacting with the epoxy resin to cure the resin composition layer is sometimes hereinafter referred to as a "curing agent". Examples of the curing agent include phenolic resins, cyanate ester resins, active ester resins, carbodiimide resins, acid anhydride resins, amine resins, benzoxazine resins, thiol resins, etc. As the curing agent, carbodiimide resins, phenolic resins, and active ester resins are preferred, and among them, from the viewpoint of significantly obtaining the effects of the present invention and improving the adhesion to the metal foil, carbodiimide resins are more preferred. The curing agent can be used alone as one kind, or two or more kinds can be used in combination. In one embodiment, the thermosetting resin includes an epoxy resin, a carbodiimide resin, and a phenolic resin.

[0045] The epoxy resin is a thermosetting resin having an epoxy group. Examples of the epoxy resin include tetramethylbisphenol 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, triphenol 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, glycidylamine 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, epoxy resin containing a spiro ring, cyclohexane type epoxy resin, cyclohexanedimethanol type epoxy resin, naphthalene ether type epoxy resin, trimethylol type epoxy resin, tetraphenylethane type epoxy resin, isocyanurate type epoxy resin, phenolphthalimidine type epoxy resin, etc. The epoxy resin can be used alone as one kind, or two or more kinds can be used in combination.

[0046] (B) Among thermosetting resins, as the epoxy resin, it is preferably an epoxy resin having two or more epoxy groups in one molecule. With respect to 100% by mass of the epoxy resin, 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.

[0047] Among epoxy resins, there are epoxy resins that are liquid at a temperature of 20°C (hereinafter sometimes referred to as "liquid epoxy resins") and epoxy resins that are solid at a temperature of 20°C (hereinafter sometimes referred to as "solid epoxy resins"). In the resin composition layer, as the epoxy resin, it may contain only a liquid epoxy resin, or it may contain only a solid epoxy resin, or it may also contain a liquid epoxy resin and a solid epoxy resin in combination.

[0048] As the liquid epoxy resin, a liquid epoxy resin having two or more epoxy groups in one molecule is preferred.

[0049] As the liquid epoxy resin, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol AF type epoxy resin, naphthalene type epoxy resin, glycidyl ester type epoxy resin, glycidyl amine type epoxy resin, phenol novolac type epoxy resin, alicyclic epoxy resin having an ester skeleton, cyclohexane type epoxy resin, cyclohexanedimethanol type epoxy resin, and epoxy resin having a butadiene structure are preferred, and glycidyl amine type epoxy resin, bisphenol A type epoxy resin, and bisphenol F type epoxy resin are more preferred, and bisphenol A type epoxy resin and bisphenol F type epoxy resin are further preferred.

[0050] As specific examples of the liquid epoxy resin, there can be mentioned "HP4032", "HP4032D", "HP4032SS" (naphthalene-type epoxy resin) manufactured by DIC Corporation; "828US", "828EL", "jER828EL", "825", "EPIKOTE 828EL" (bisphenol A-type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "jER807", "1750" (bisphenol F-type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "jER152" (phenolic novolac-type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "630", "630LSD", "604" (glycidylamine-type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "ED-523T" (Glycirol-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. They can be used alone, or two or more of them can be used in combination.

[0051] 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.

[0052] As the solid epoxy resin, tetramethylbisphenol-type epoxy resin (xylenol-type epoxy resin), naphthalene-type epoxy resin, naphthalene-type tetrafunctional epoxy resin, naphthol novolac-type epoxy resin, cresol novolac-type epoxy resin, dicyclopentadiene-type epoxy resin, triphenol-type epoxy resin, naphthol-type epoxy resin, biphenyl-type epoxy resin, naphthyl ether-type epoxy resin, anthracene-type epoxy resin, bisphenol A-type epoxy resin, bisphenol AF-type epoxy resin, phenol aralkyl-type epoxy resin, tetraphenylethane-type epoxy resin, phenol benzopyrrolone-type epoxy resin are preferred, and xylenol-type epoxy resin and biphenyl-type epoxy resin are more preferred.

[0053] As specific examples of solid epoxy resins, there can be mentioned "HP4032H" (naphthalene-type epoxy resin) manufactured by DIC Corporation; "HP-4700", "HP-4710" (naphthalene-type tetrafunctional epoxy resins) 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 resins) manufactured by DIC Corporation; "EXA-7311", "EXA-7311-G3", "EXA-7311-G4", "EXA-7311-G4S", "HP6000" (naphthalene ether-type epoxy resins) manufactured by DIC Corporation; "EPPN-502H" (triphenol-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 resins) manufactured by Nippon Kayaku Co., Ltd.; "ESN475V", "ESN4100V" (naphthalene-type epoxy resins) 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" (xylenol-type epoxy resins) 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" (phenol benzopyrrolidone-type epoxy resin) manufactured by Nippon Kayaku Co., Ltd., etc. They can be used alone or in combination of two or more.

[0054] When a liquid epoxy resin and a solid epoxy resin are used in combination 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.

[0055] The epoxy equivalent of the epoxy resin is preferably from 50 g / eq. to 5000 g / eq., more preferably from 60 g / eq. to 3000 g / eq., further preferably from 80 g / eq. to 2000 g / eq., and particularly preferably from 110 g / eq. to 1000 g / eq. The epoxy equivalent represents the mass of the resin per 1 equivalent of epoxy groups. This epoxy equivalent can be measured in accordance with JIS K 7236.

[0056] The weight-average molecular weight (Mw) of the epoxy resin is preferably from 100 to 5000, more preferably from 250 to 3000, and further preferably from 400 to 1500. The weight-average molecular weight of the resin can be measured by gel permeation chromatography (GPC) as a value in terms of polystyrene conversion.

[0057] When the non-volatile components in the resin composition layer are set to 100% by mass, the content of the epoxy resin as the (B) thermosetting resin is preferably 1% by mass or more, more preferably 5% by mass or more, particularly preferably 10% by mass or more, preferably 45% by mass or less, more preferably 40% by mass or less, and particularly preferably 30% by mass or less.

[0058] When the resin components in the resin composition layer are set to 100% by mass, the content of the epoxy resin as the (B) thermosetting resin is preferably 30% by mass or more, more preferably 35% by mass or more, particularly preferably 40% by mass or more, preferably 85% by mass or less, more preferably 80% by mass or less, and particularly preferably 75% by mass or less.

[0059] Specific examples of the polyphenylene ether resin as the (B) component include "NORYL SA90" manufactured by SABIC. The polyphenylene ether resin may have one or more (preferably two or more) styryl or vinylphenyl groups in one molecule. As such polyphenylene ether resins, in addition to styrene monomers, for example, "OPE-2St", "OPE-2St1200", "OPE-2St 2200" (all manufactured by Mitsubishi Gas Chemical Company) etc. can be cited.

[0060] When the non-volatile components in the resin composition layer are set to 100% by mass, the content of the polyphenylene ether resin as the (B) thermosetting resin is preferably 1% by mass or more, more preferably 1.5% by mass or more, further preferably 2% by mass or more, preferably 10% by mass or less, more preferably 5% by mass or less, and further preferably 3% by mass or less.

[0061] When the resin component in the resin composition layer is 100% by mass, the content of the polyphenylene ether resin as the (B) thermosetting resin is preferably 1% by mass or more, more preferably 2% by mass or more, still more preferably 3% by mass or more, preferably 15% by mass or less, more preferably 12% by mass or less, and still more preferably 10% by mass or less.

[0062] The radically polymerizable resin as the component (B) is not particularly limited as long as it has one or more (preferably two or more) radically polymerizable unsaturated groups in one molecule. 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.

[0063] The maleimide resin is not particularly limited as long as it has one or more (preferably two or more) maleimide groups (2,5-dihydro-2,5-dioxo-1H-pyrrol-1-yl) in one molecule. Examples of the maleimide resin include: (1) maleimide resins containing an aliphatic skeleton (preferably an aliphatic skeleton having 36 carbon atoms derived from a dimer diamine) such as "BMI-3000J", "BMI-5000", "BMI-1400", "BMI-1500", "BMI-1700", "BMI-689" (all manufactured by Designer Molecules Inc.), and "SLK6895-T90" (manufactured by Shin-Etsu Chemical Co., Ltd.); (2) maleimide resins containing an indane skeleton described in Japanese Invention Association Publication Technical Report Public Technical No. 2020-500211; (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 KI Kasei Co., Ltd.).

[0064] As the (meth)acrylic resin, as long as it has one or more (preferably two or more) (meth)acryloyl groups in one molecule, its type is not particularly limited, and it may also be a monomer or an oligomer. Here, the term "(meth)acryloyl group" is a general term for acryloyl group and methacryloyl group. As the (meth)acrylic resin, in addition to (meth)acrylate monomers, for example, "(meth)acrylic resins such as "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.) can be cited.

[0065] Regarding the content of the free-radical polymerizable resin as the (B) thermosetting resin, when the non-volatile content in the resin composition layer is set to 100% by mass, it is preferably 0.5% by mass or more, more preferably 1% by mass or more, further preferably 1.5% by mass or more, preferably 10% by mass or less, more preferably 5% by mass or less, and further preferably 3% by mass or less.

[0066] Regarding the content of the free-radical polymerizable resin as the (B) thermosetting resin, when the resin component in the resin composition layer is set to 100% by mass, it is preferably 1% by mass or more, more preferably 2% by mass or more, further preferably 3% by mass or more, preferably 15% by mass or less, more preferably 12% by mass or less, and further preferably 10% by mass or less.

[0067] As the phenol 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. When the phenol resin is combined with an epoxy resin, it can react with the epoxy resin to cure the resin composition layer, and thus is sometimes referred to as a "phenolic curing agent". From the viewpoint of significantly obtaining the effects of the present invention, the phenol resin is preferably a phenol resin having a novolak structure. In addition, from the viewpoint of adhesion, a nitrogen-containing phenol resin is preferred, and a phenol resin containing a triazine skeleton is more preferred. Among them, from the viewpoint of significantly obtaining the effects of the present invention, a linear novolak resin containing a triazine skeleton is preferred. Specific examples of the phenol resin include, for example, "MEH-7700", "MEH-7810", "MEH-7851" manufactured by Meiji Seika Kaisha, 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.

[0068] As the active ester resin, it is generally preferred to use compounds having two or more highly reactive ester groups in one molecule, such as phenolic esters, thiophenolic esters, N-hydroxyamine esters, esters of heterocyclic hydroxy compounds, etc. When combined with an epoxy resin, the active ester resin can react with the epoxy resin to cure the resin composition layer, and thus is sometimes referred to as an "active ester-based curing agent". The active ester resin is preferably a resin 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. In particular, from the viewpoint of improving the swelling resistance to high-temperature reflow soldering, 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, phenolphthalin, 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, phloroglucinol, pyrogallol, dicyclopentadiene-type diphenol compound, novolak resin, etc. Here, the "dicyclopentadiene-type diphenol compound" refers to a diphenol compound obtained by condensing two molecules of phenol with one molecule of dicyclopentadiene.

[0069] 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 a novolak resin, and an active ester resin containing a benzoylated product of a novolak resin are preferred, and at least one selected from the dicyclopentadiene-type active ester resin and the naphthalene-type active ester resin is more preferred. As the dicyclopentadiene-type active ester resin, an active ester resin containing a dicyclopentadiene-type diphenol structure is preferred.

[0070] Regarding commercially available products of active ester resins, for example, as active ester resins containing a dicyclopentadiene-type diphenol structure, there can be mentioned "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 active ester resins containing a naphthalene structure, there can be mentioned "EXB-8100L-65T", "EXB-8150-60T", "EXB-8150-62T", "EXB-9416-70BK", "HPC-8150-62T", "EXB-8" (manufactured by DIC Corporation); as active ester resins containing phosphorus, there can be mentioned "EXB9401" (manufactured by DIC Corporation); as active ester resins which are acetylated products of linear phenolic resins, there can be mentioned "DC808" (manufactured by Mitsubishi Chemical Corporation); as active ester resins which are benzoylated products of linear phenolic resins, there can be mentioned "YLH1026", "YLH1030", "YLH1048" (manufactured by Mitsubishi Chemical Corporation); as active ester resins containing a styryl group and a naphthalene structure, there can be mentioned "PC1300-02-65MA" (manufactured by AIR WATER Corporation), etc.

[0071] As the cyanate ester resin, a compound having one or more, preferably two or more, cyanate ester groups in one molecule can be used. The cyanate ester resin can react with an epoxy resin to cure the resin composition layer when combined with the epoxy resin, and thus is sometimes referred to as a "cyanate ester-based curing agent". As the cyanate ester resin, there can be mentioned, for example, bifunctional cyanate ester resins such as bisphenol A dicyanate, polyphenol cyanate (oligomeric (3-methylidene-1,5-phenylene cyanate)), 4,4'-methylenebis(2,6-dimethylphenyl cyanate), 4,4'-ethylenediphenyl dicyanate, hexafluorobisphenol A dicyanate, 2,2-bis(4-cyanate phenyl) propane, 1,1-bis(4-cyanate phenyl) methane, bis(4-cyanate-3,5-dimethylphenyl) methane, 1,3-bis(4-cyanate phenyl-1-(methylethylidene)) benzene, bis(4-cyanate phenyl) sulfide, and bis(4-cyanate phenyl) ether; polyfunctional cyanate ester resins derived from linear phenolic resins and cresol phenolic resins, and prepolymers obtained by triazine-forming a part of these cyanate ester resins. As specific examples of the cyanate ester resin, there can be mentioned "PT30" and "PT60" (both are linear phenolic resin-type polyfunctional cyanate ester resins), "BA230", "BA230S75" (prepolymers in which a part or all of bisphenol A dicyanate has been triazine-formed to form a trimer) manufactured by arxada company, etc.

[0072] As the carbodiimide resin, a compound having one or more, preferably two or more carbodiimide structures in one molecule can be used. When combined with an epoxy resin, the carbodiimide resin can react with the epoxy resin to cure the resin composition layer, and thus is sometimes referred to as a "carbodiimide-based curing agent". Specific examples of the carbodiimide resin include: aliphatic biscarbodiimides such as tetramethylene-bis(tert-butylcarbodiimide) and cyclohexane bis(methylene-tert-butylcarbodiimide); biscarbodiimides such as phenyl-bis(xylenylcarbodiimide); aliphatic polycarbodiimides such as polyhexamethylene carbodiimide, polytrimethylhexamethylene carbodiimide, polycyclohexylene carbodiimide, poly(methylenebiscyclohexylene carbodiimide), and poly(isophorone carbodiimide); aromatic polycarbodiimides such as poly(phenylcarbodiimide), poly(naphthylcarbodiimide), poly(tolylene carbodiimide), poly(methyldiisopropylphenylcarbodiimide), poly(triethylphenylcarbodiimide), poly(diethylphenylcarbodiimide), poly(triisopropylphenylcarbodiimide), poly(diisopropylphenylcarbodiimide), poly(xylenylcarbodiimide), poly(tetramethylxylenylcarbodiimide), poly(methylenediphenylcarbodiimide), and poly[methylenebis(methylphenyl)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", "Hycasyl 510", etc. manufactured by Lanxess Corporation.

[0073] As the acid anhydride resin, a compound having one or more, preferably two or more acid anhydride groups in one molecule can be used. The acid anhydride resin can react with the epoxy resin when combined with an epoxy group to cure the resin composition layer, and thus 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, methylnadic anhydride, hydrogenated methylnadic anhydride, trialkyltetrahydrophthalic anhydride, dodecenyl succinic anhydride, 5-(2,5-dioxotetrahydro-3-furanyl)-3-methyl-3-cyclohexene-1,2-dicarboxylic anhydride, trimellitic anhydride, pyromellitic anhydride, benzophenone tetracarboxylic dianhydride, biphenyltetracarboxylic dianhydride, naphthalenetetracarboxylic dianhydride, oxydiphthalic dianhydride, 3,3'-4,4'-diphenylsulfone tetracarboxylic dianhydride, 1,3,3a,4,5,9b-hexahydro-5-(tetrahydro-2,5-dioxo-3-furanyl)-naphtho[1,2-c]furan-1,3-dione, ethylene glycol bis(trimellitate), polymer-type acid anhydrides such as styrene-maleic acid resin obtained by copolymerizing styrene and maleic acid, etc. 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 Resonac Co., Ltd.; "EF-30", "EF-40", "EF-60", "EF-80", etc. manufactured by Cray Valley Company.

[0074] As the amine resin, a compound having one or more, preferably two or more, amino groups in one molecule can be used. When combined with an epoxy group, the amine resin can react with the epoxy resin to cure the resin composition layer, and is therefore sometimes referred to as an "amine curing agent". As the amine resin, for example, aliphatic amines, polyether amines, alicyclic amines, aromatic amines, etc. can be cited, among which aromatic amines are preferred. The amine resin is preferably a primary amine or a secondary amine, more preferably a primary amine. Specific examples of the amine resin include 4,4'-methylenebis(2,6-dimethylaniline), 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenyl sulfone, 3,3'-diaminodiphenyl sulfone, metaphenylenediamine, metaxylylenediamine, 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) bis(4-aminophenoxy)phenyl)sulfone, bis(4-(3-aminophenoxy)phenyl)sulfone, and the like. Examples of commercially available amine resins include “SEIKACURE-S” manufactured by SEIKA Corporation; “KAYABOND C-200S”, “KAYABOND C-100”, “KAYAHARD AA”, “KAYAHARD AB”, and “KAYAHARD AS” manufactured by Nippon Kayaku Co., Ltd.; “Epicure W” manufactured by Mitsubishi Chemical Corporation; and “DTDA” manufactured by Sumitomo Seika Chemicals Co., Ltd.

[0075] When combined with an epoxy resin, the benzoxazine resin can react with the epoxy resin to cure the resin composition layer, and therefore is sometimes referred to as a "benzoxazine-based curing agent". Specific examples of the benzoxazine resin include "JBZ-OP100D" and "ODA-BOZ" manufactured by JFE Chemical Co., Ltd.; "HFB2006M" manufactured by Showa High Molecular Co., Ltd.; and "Pd" and "Fa" manufactured by Shikoku Chemical Industry Co., Ltd.

[0076] When combined with an epoxy resin, a thiol resin can react with the epoxy resin to cure the resin composition layer, and therefore is sometimes referred to as a "thiol-based curing agent." Examples of the thiol resin include trimethylolpropane tris(3-mercaptopropionate), pentaerythritol tetrakis(3-mercaptobutyrate), and tris(3-mercaptopropyl)isocyanurate.

[0077] The equivalent weight of the active groups 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 equivalent weight of the active groups is the mass of the curing agent per 1 equivalent of active groups.

[0078] The weight-average molecular weight (Mw) of the curing agent is preferably 100 to 5000, more preferably 250 to 3000, still more preferably 400 to 1500. The weight-average molecular weight of the resin can be measured by gel permeation chromatography (GPC) as a value in terms of polystyrene conversion.

[0079] When the number of epoxy groups of the epoxy resin is set to 1, the number of active groups of the curing agent is preferably 0.01 or more, more preferably 0.05 or more, still more preferably 0.1 or more, preferably 5 or less, more preferably 3 or less, and particularly preferably 2 or less. The "number of epoxy groups of the epoxy resin" represents the value obtained by summing up all the values obtained by dividing the mass of the epoxy resin present in the resin composition layer by the epoxy equivalent. In addition, the "number of active groups of the curing agent" represents the value obtained by summing up all the values obtained by dividing the mass of the curing agent present in the resin composition layer by the equivalent weight of the active groups.

[0080] When the non-volatile components in the resin composition layer are set to 100% by mass, the content of the curing agent as the (B) thermosetting resin is preferably 1% by mass or more, more preferably 3% by mass or more, still more preferably 5% by mass or more, preferably 25% by mass or less, more preferably 20% by mass or less, and still more preferably 15% by mass or less.

[0081] When the resin components in the resin composition layer are set to 100% by mass, the content of the curing agent as the (B) thermosetting resin is preferably 10% by mass or more, more preferably 15% by mass or more, still more preferably 20% by mass or more, preferably 55% by mass or less, more preferably 50% by mass or less, and still more preferably 45% by mass or less.

[0082] When the non-volatile components in the resin composition layer are set to 100% by mass, the content of the (B) thermosetting resin is preferably 10% by mass or more, more preferably 15% by mass or more, still more preferably 20% by mass or more, preferably 65% by mass or less, more preferably 50% by mass or less, still more preferably 45% by mass or less, and 40% by mass or less.

[0083] When the resin component in the resin composition layer is 100% by mass, the content of (B) thermosetting resin is preferably 60% by mass or more, more preferably 70% by mass or more, still more preferably 80% by mass or more, preferably 97% by mass or less, more preferably 95% by mass or less, and still more preferably 94% by mass or less.

[0084] -(C) Inorganic filler- The resin composition layer contains an inorganic filler as the (C) component. By using the resin composition layer containing the (C) component, a cured product with a low dielectric loss tangent can be obtained. The (C) inorganic filler can be used alone or in combination of two or more in any ratio.

[0085] (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. Examples of the material of the (C) inorganic filler include silica, alumina, glass, cordierite, silicon oxide, barium sulfate, barium carbonate, talc, clay, mica powder, zinc oxide, hydrotalcite, boehmite, aluminum hydroxide, magnesium hydroxide, calcium carbonate, magnesium carbonate, magnesium oxide, boron nitride, aluminum nitride, manganese nitride, aluminum borate, strontium carbonate, strontium titanate, calcium titanate, magnesium titanate, bismuth titanate, titanium oxide, zirconium oxide, barium titanate, barium zirconate titanate, barium zirconate, calcium zirconate, zirconium phosphate, and zirconium tungstate phosphate, etc. Among them, silica is particularly preferred. Examples of silica include amorphous silica, fused silica, crystalline silica, synthetic silica, hollow silica, etc. In addition, spherical silica is preferred as silica.

[0086] Examples of commercially available products of the (C) inorganic filler include "SP60-05", "SP507-05" manufactured by Nippon Steel Chemical Materials 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.; "Silfil NSS-3N", "Silfil NSS-4N", "Silfil NSS-5N" manufactured by Tokuyama Corporation; "CellSpheres", "MGH-005", etc. manufactured by Pacific Cement Co., Ltd.

[0087] (C) The average particle diameter of the inorganic filler is not particularly limited, preferably 10 μm or less, more preferably 5 μm or less, further preferably 3 μm or less, still more preferably 2 μm or less, and particularly preferably 1.5 μm or less. The lower limit of the average particle diameter of the inorganic filler is not particularly limited, preferably 0.01 μm or more, more preferably 0.05 μm or more, further preferably 0.1 μm or more, and particularly preferably 0.2 μm or more. The average particle diameter of the inorganic filler can be measured by the laser diffraction / scattering method based on the Mie scattering theory. Specifically, a particle size distribution of the inorganic filler can be prepared on a volume basis by a laser diffraction scattering type particle size distribution measuring device, and the median particle size thereof can be measured as the average particle diameter. As the measurement sample, a sample obtained by weighing 100 mg of the inorganic filler and 10 g of methyl ethyl ketone in a vial and dispersing them ultrasonically for 10 minutes can be used. For the measurement sample, using a laser diffraction type particle size distribution measuring device, the light source wavelength is set to blue and red, and the volume-based particle size distribution of the inorganic filler is measured by the flow cell method, and the average particle diameter is calculated as the median particle size from the obtained particle size distribution. As the laser diffraction type particle size distribution measuring device, for example, "LA-960" manufactured by Horiba, Ltd. can be mentioned.

[0088] (C) The specific surface area of the inorganic filler is not particularly limited, preferably 0.1 m 2 / g or more, more preferably 0.5 m 2 / g or more, further preferably 1 m 2 / g or more, particularly preferably 3 m 2 / g or more. The upper limit of the specific surface area of the inorganic filler is not particularly limited, preferably 100 m 2 / g or less, more preferably 70 m 2 / g or less, further preferably 50 m 2 / g or less, still further preferably 30 m 2 / g or less, particularly preferably 10 m 2 / g or less. The specific surface area of the inorganic filler can be obtained by the BET method by adsorbing nitrogen on the surface of the sample using a specific surface area measuring device (Macsorb HM-1210 manufactured by Mountech Co., Ltd.) and calculating the specific surface area using the BET multipoint method.

[0089] From the viewpoint of improving moisture resistance and dispersibility, the (C) inorganic filler is preferably treated with a surface treatment agent. Examples of the surface treatment agent include fluorine-containing silane coupling agents, amino-silane coupling agents, epoxy-silane coupling agents, mercapto-silane coupling agents, silane coupling agents, alkoxysilanes, organosilazane compounds, titanate coupling agents, and the like. In addition, the surface treatment agent may be used alone as one kind, or two or more kinds may be used in any combination.

[0090] Examples of commercially available products of the surface treatment agent include "KBM403" (3-glycidoxypropyltrimethoxysilane), "KBM803" (3-mercaptopropyltrimethoxysilane), "KBE903" (3-aminopropyltriethoxysilane), "KBM573" (N-phenyl-3-aminopropyltrimethoxysilane), "SZ-31" (hexamethyldisilazane), "KBM103" (phenyltrimethoxysilane), "KBM-4803" (long-chain epoxy type silane coupling agent), "KBM-7103" (3,3,3-trifluoropropyltrimethoxysilane), etc., all manufactured by Shin-Etsu Chemical Co., Ltd.

[0091] From the viewpoint of improving the dispersibility of the inorganic filler, the degree of surface treatment with the surface treatment agent is preferably within a specified 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 still more preferably surface-treated with 0.3% to 2% by mass.

[0092] The degree of surface treatment with the surface treatment agent can be evaluated by the carbon amount per unit surface area of the inorganic filler. From the viewpoint of improving the dispersibility of the inorganic filler, the carbon amount 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 still 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 or the melt viscosity in the sheet form, it is preferably 1.0 mg / m 2 or less, more preferably 0.8 mg / m 2 or less, and still more preferably 0.5 mg / m 2 or less.

[0093] (C) The amount of carbon per unit surface area of the inorganic filler can be measured after cleaning the surface-treated inorganic filler with a solvent (such as methyl ethyl ketone (MEK)). Specifically, an adequate amount of MEK is added as a solvent to the inorganic filler surface-treated with a surface treatment agent, and ultrasonic cleaning is performed at 25 °C for 5 minutes. After removing the supernatant and drying the solid component, a carbon analyzer can be used to measure the amount of carbon per unit surface area of the inorganic filler. As the carbon analyzer, "EMIA-320V" manufactured by Horiba, Ltd. can be used, etc.

[0094] When the non-volatile components in the resin composition layer are set to 100% by mass, the content of (C) the inorganic filler is preferably 35% by mass or more, more preferably 40% by mass or more, further preferably more than 40% by mass, 50% by mass or more, 55% by mass or more. The upper limit is preferably 85% by mass or less, more preferably 80% by mass or less, and further preferably 75% by mass or less.

[0095] (C) The inorganic filler is preferably contained in the resin composition layer in a uniformly dispersed state. For example, in the cross-section of the resin composition layer in the direction perpendicular to the surface of the metal foil, the content of (C) the inorganic filler contained in the resin composition layer in the region at a distance of 0 μm to 15 μm from the boundary between the metal foil and the resin composition layer is preferably within the above range, and the content of (C) the inorganic filler contained in the resin composition layer in the region of the resin composition layer where the distance exceeds 15 μm to the surface on the side opposite to the surface joined to the metal foil is also preferably within the above range.

[0096] -(D) Flexible resin- The resin composition layer may contain (D) a flexible resin as the (D) component. The (D) flexible resin as the (D) component does not include substances belonging to the above (A) to (C) components. By making the resin composition layer contain (D) a flexible resin, a cured product with excellent film flexibility can be obtained. The (D) component can be used alone or in combination of two or more.

[0097] Examples of the (D) flexible resin include polyimide resin, polyvinyl acetal resin, polyolefin resin, polybutadiene resin, polyamideimide resin, polyetherimide resin, polysulfone resin, polyethersulfone resin, polycarbonate resin, polyetheretherketone resin, polyester resin, etc. Among them, from the viewpoint of improving the adhesion to the metal foil, the (D) flexible resin preferably contains a polyimide resin.

[0098] As the polyvinyl acetal resin, examples thereof include polyvinyl formal resin and polyvinyl butyral resin, and polyvinyl butyral resin is preferred. Specific examples of the polyvinyl acetal resin include S-LEC BH series, BX series (e.g., BX-5Z), KS series (e.g., KS-1), BL series, BM series, etc. manufactured by Sekisui Chemical Co., Ltd.

[0099] As the polyolefin resin, examples thereof include ethylene-based copolymer resins such as low density polyethylene, ultra-low density polyethylene, high density polyethylene, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, and ethylene-methyl acrylate copolymer; polyolefin-based polymers such as polypropylene and ethylene-propylene block copolymer.

[0100] As the polybutadiene resin, examples thereof include resins containing a hydrogenated polybutadiene skeleton, polybutadiene resins containing a hydroxyl group, polybutadiene resins containing a phenolic hydroxyl group, polybutadiene resins containing a carboxyl group, polybutadiene resins containing an acid anhydride group, polybutadiene resins containing an epoxy group, polybutadiene resins containing an isocyanate group, polybutadiene resins containing a urethane group, polyphenylene ether-polybutadiene resins, etc.

[0101] Specific examples of the polyamideimide resin include "VYLOMAX HR11NN" and "VYLOMAX HR16NN" manufactured by Toyobo Co., Ltd. Specific examples of the polyamideimide resin include modified polyamideimides such as "KS9100" and "KS9300" (polyamideimide containing a polysiloxane skeleton) manufactured by Hitachi Chemical Co., Ltd.

[0102] Specific examples of the polyethersulfone resin include "PES5003P" manufactured by Sumitomo Chemical Co., Ltd.

[0103] Specific examples of the polysulfone resin include polysulfones "P1700", "P3500", etc. manufactured by Solvay Advanced Polymers.

[0104] Specific examples of the polyetherimide resin include "Ultem" manufactured by GE.

[0105] As the polycarbonate resin, examples thereof include a carbonate resin containing a hydroxyl group, a carbonate resin containing a phenolic hydroxyl group, a carbonate resin containing a carboxyl group, a carbonate resin containing an acid anhydride group, a carbonate resin containing an isocyanate group, a carbonate resin containing a urethane group, etc. Specific examples of the polycarbonate resin include "FPC0220" 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., etc. Specific examples of the polyetheretherketone resin include "Sumiploy K" manufactured by Sumitomo Chemical Company, etc.

[0106] As the polyester resin, examples thereof include polyethylene terephthalate resin, polyethylene naphthalate resin, polybutylene terephthalate resin, polybutylene naphthalate resin, polypropylene terephthalate resin, polypropylene naphthalate resin, polycyclohexanedimethylene terephthalate resin, etc.

[0107] As the polyimide resin of the component (D), 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, an ester bond is preferably present. The polyimide resin generally includes a resin obtained by an imidization reaction of a diamine compound and an acid anhydride.

[0108] The diamine compound used for preparing the polyimide resin is not particularly limited, and examples thereof include aliphatic diamine compounds and aromatic diamine compounds. Among them, as the diamine compound, an aromatic diamine compound is preferably used. From the viewpoint of increasing the glass transition temperature of the cured product, the diamine compound preferably has an ester bond, and more preferably an aromatic diamine compound having an ester bond.

[0109] As the aliphatic diamine compound, examples thereof include linear aliphatic diamine compounds such as 1,2-ethylenediamine, 1,2-diaminopropane, 1,3-diaminopropane, 1,4-diaminobutane, 1,6-hexanediamine, 1,5-diaminopentane, 1,10-diaminodecane, etc.; branched aliphatic diamine compounds such as 1,2-diamino-2-methylpropane, 2,3-diamino-2,3-butane, and 2-methyl-1,5-diaminopentane, etc.; alicyclic diamine compounds such as 1,3-bis(aminomethyl)cyclohexane, 1,4-bis(aminomethyl)cyclohexane, 1,4-diaminocyclohexane, 4,4'-methylenebis(cyclohexylamine), etc.; dimer acid type diamine (hereinafter also referred to as "dimer diamine"), etc., and dimer acid type diamine is preferably used.

[0110] The so-called dimer acid type diamine means that the two terminal carboxylic acid groups (-COOH) of the dimer acid are replaced by aminomethyl (-CH 2 -NH2 ) or amino group (-NH 2 )-substituted diamine compounds. The dimer acid is a known compound obtained by dimerizing unsaturated fatty acids (preferably unsaturated fatty acids having 11 to 22 carbon atoms, particularly preferably unsaturated fatty acids having 18 carbon atoms), and its industrial manufacturing process has been roughly standardized in the industry. For dimer acids, in particular, dimer acids mainly composed of dimer acids having 36 carbon atoms obtained by dimerizing inexpensive and easily available unsaturated fatty acids having 18 carbon atoms such as oleic acid and linoleic acid can be easily obtained. In addition, for dimer acids, depending on the manufacturing method, degree of purification, etc., they sometimes contain any amount of monomeric acids, trimeric acids, other polymeric fatty acids, etc. In addition, although double bonds remain after the polymerization reaction of unsaturated fatty acids, in this specification, hydrogenated products with reduced unsaturation obtained by further hydrogenation reaction are also included in the dimer acid. For dimer acid type diamines, commercially available products can be obtained, and examples include "PRIAMINE 1073", "PRIAMINE 1074", "PRIAMINE 1075" manufactured by Croda Japan Co., Ltd., "VERSAMINE 551", "VERSAMINE 552" manufactured by Cognis Japan Co., Ltd., etc.

[0111] As the aromatic diamine compound, examples include benzenediamine compounds, naphthalenediamine compounds, diphenylamine compounds, etc., and diphenylamine compounds are preferred.

[0112] The so-called benzenediamine compound refers to a compound formed by a benzene ring having 2 amino groups. Furthermore, the benzene ring here may arbitrarily have 1 to 3 substituents. Specifically, as the benzenediamine compound, examples include 1,4-benzenediamine, 1,2-benzenediamine, 1,3-benzenediamine, 2,4-diaminotoluene, 2,6-diaminotoluene, 3,5-diaminobiphenyl, 2,4,5,6-tetrafluoro-1,3-benzenediamine, etc.

[0113] The substituents are not particularly limited, and examples include halogen atoms, -OH, -O-C 1-6 alkyl, -N(C 1-10 alkyl) 2 , C 1-20 alkyl, C 2-30 alkenyl, C 2-30 alkynyl, C 6-10 aryl, -NH 2 , -CN, -C(O)O-C 1-10 alkyl, -COOH, -C(O)H, -NO 2 , etc. Here, "C p-qThe term “(where p and q are positive integers satisfying p < q)” means that the number of carbon atoms in the organic group described immediately after this term is p to q. For example, the expression “C 1-10 alkyl” means an alkyl group having 1 to 10 carbon atoms. These substituents may also combine with each other to form a ring, and the ring structure also includes a spiro ring or a fused ring.

[0114] The naphthalenediamine compound refers to a compound formed by a naphthalene ring having 2 amino groups. Further, the naphthalene ring here may optionally have 1 to 3 substituents. As the substituents, they are the same as the substituents that the phenylenediamine compound may optionally have. Specifically, as the naphthalenediamine compound, 1,5-diaminonaphthalene, 1,8-diaminonaphthalene, 2,6-diaminonaphthalene, 2,3-diaminonaphthalene, etc. can be cited.

[0115] The diphenylamine compound refers to a compound containing 2 aniline structures in the molecule. Further, the 2 benzene rings in the 2 aniline structures may each further optionally have 1 to 3 substituents. As the substituents, they are the same as the substituents that the phenylenediamine compound may optionally have. The 2 aniline structures in the diphenylamine compound may be directly bonded and / or bonded via one or two linking structures having 1 to 100 backbone atoms selected from carbon atoms, oxygen atoms, sulfur atoms, and nitrogen atoms. The diphenylamine compound also includes a compound in which the 2 aniline structures are bonded by 2 bonds.

[0116] As the “linking structure” in the diphenylamine compound, specifically, -NHCO-, -CONH-, -OCO-, -COO-, -CH 2 -, -CH 2 CH 2 -, -CH 2 CH 2 CH 2 -, -CH 2 CH 2 CH 2 CH 2 -, -CH 2 CH 2 CH 2 CH 2 CH 2 -, -CH(CH 3 )-, -C(CH 3 ) 2 -, -C(CF 3 ) 2 -, -CH=CH-, -O-, -S-, -CO-, -SO 2 -, -NH-, -Ph-, -Ph-Ph-, -C(CH 3 ) 2 -Ph-C(CH 3 )2 -, -O-Ph-O-, -O-Ph-Ph-O-, -O-Ph-SO 2 -Ph-O-, -O-Ph-C(CH 3 ) 2 -Ph-O-, -Ph-CO-O-Ph-, -C(CH 3 ) 2 -Ph-C(CH 3 ) 2 -, -O-Ph-C(CH 3 ) 2 -Ph-C(CH 3 ) 2 -Ph-O-, -Ph-O-Ph-C(CH 3 ) 2 -Ph-C(CH 3 ) 2 -Ph-O-Ph-, the groups represented by the following formulas (I) and (II), and the groups formed by combining them, etc. In this specification, "Ph" represents 1,4-phenylene, 1,3-phenylene or 1,2-phenylene. Among them, as the linking structure, -COO-, -Ph-CO-O-Ph-, -C(CH 3 ) 2 -Ph-C(CH 3 ) 2 -, -O-Ph-C(CH 3 ) 2 -Ph-C(CH 3 ) 2 -Ph-O-, or -Ph-O-Ph-C(CH 3 ) 2 -Ph-C(CH 3 ) 2 -Ph-O-Ph-.

[0117] [Chemical formula 1]

[0118] In one embodiment, as the diamine compound, the diamine compound represented by the following formula (D-1) is preferred. [Chemical formula 2] (In formula (D-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 , R 1 ~R8 at least one of them is -X 10 -R 10 , X 9 each independently represents a single bond, -NR 9’ -, -O-, -S-, -CO-, -SO 2 -, -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, R 9’ each independently represents a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted alkenyl group, X 10 each independently represents a single bond, -(substituted or unsubstituted alkylene)-, -NH-, -O-, -S-, -CO-, -SO 2 -, -NHCO-, -CONH-, -OCO- or -COO-, R 10 each independently represents a substituted or unsubstituted aryl group, or a substituted or unsubstituted heteroaryl group.)

[0119] R in formula (D-1) 9 and R 9 ' represents an alkyl group which means a straight-chain, branched-chain or cyclic monovalent aliphatic saturated hydrocarbon group. As the alkyl group, an alkyl group having 1 to 6 carbon atoms is preferred, and an alkyl group having 1 to 3 carbon atoms is more preferred. Examples of such an alkyl group include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, pentyl, isopentyl, neopentyl, cyclopentyl, cyclohexyl, etc.

[0120] R in formula (D-1) 9 and R 9 ' represents an alkenyl group which means a straight-chain, branched-chain 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 preferred, and an alkenyl group having 2 or 3 carbon atoms is more preferred. Examples of such an alkenyl group include vinyl, 1-propenyl, 2-propenyl, 2-methyl-1-propenyl, 1-buteneyl, 2-buteneyl, 3-buteneyl, 3-methyl-2-buteneyl, 1-pentenyl, 2-pentenyl, 3-pentenyl, 4-pentenyl, 4-methyl-3-pentenyl, 1-hexenyl, 3-hexenyl, 5-hexenyl, 2-cyclohexenyl, etc. As the substituent of the alkenyl group in the "substituted or unsubstituted alkenyl group", there is no particular limitation, 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 hydroxyl group, a carboxyl group, a sulfo group, etc. As the number of substituents, 1 to 3 are preferred, and 1 is more preferred.

[0121] As the substituents of the alkyl group in "substituted or unsubstituted alkyl" and the substituents of the alkenyl group in "substituted or unsubstituted alkenyl", there are no particular limitations, and examples thereof include a halogen atom, a cyano group, an alkoxy group, an amino group, a nitro group, a hydroxyl group, a carboxyl group, a sulfo group, etc. The number of substituents is preferably 1 to 3, and more preferably 1.

[0122] An alkoxy group refers to a monovalent group formed by bonding an alkyl group to an oxygen atom (alkyl-O-). As the alkoxy group, an alkoxy group having 1 to 6 carbon atoms is preferred, and an alkoxy group having 1 to 3 carbon atoms is more preferred. Examples of such an alkoxy group 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, etc.

[0123] X in formula (D-1) 10 The alkylene group represented refers to a straight-chain, branched-chain or cyclic divalent aliphatic saturated hydrocarbon group, preferably an alkylene group having 1 to 6 carbon atoms, and more preferably an alkylene group having 1 to 3 carbon atoms. Examples of the alkylene group include -CH 2 -, -CH 2 -CH 2 -, -CH(CH 3 )-, -CH 2 -CH 2 -CH 2 -, -CH 2 -CH(CH 3 )-, -CH(CH 3 )-CH 2 -, -C(CH 3 ) 2 -, -CH 2 -CH 2 -CH 2 -CH 2 -, -CH 2 -CH 2 -CH(CH 3 )-, -CH 2 -CH(CH 3 )-CH 2 -, -CH(CH 3 )-CH 2 -CH 2 -, -CH 2 -C(CH 3 ) 2 -, -C(CH 3 ) 2 -CH 2- etc. As the substituent of the alkylene group in "substituted or unsubstituted alkylene group", there is no particular limitation, 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 hydroxyl group, a carboxyl group, a sulfo group, etc. As the number of substituents, 1 to 3 are preferred, and 1 is more preferred.

[0124] As R in formula (D-1) 10 The aryl group represented 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 aryl groups include a phenyl group, a 1-naphthyl group, a 2-naphthyl group, etc., and a phenyl group is preferred. As the substituent of the aryl group in "substituted or unsubstituted aryl group", there is no particular limitation, 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 hydroxyl group, a carboxyl group, a sulfo group, etc. As the number of substituents, 1 to 3 are preferred, and 1 is more preferred.

[0125] R in formula (D-1) 10 The heteroaryl group represented refers to 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 5- to 12-membered (preferably 5- or 6-membered) monocyclic, bicyclic, or tricyclic (preferably monocyclic) aromatic heterocyclic group. 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, etc. As the substituent of the heteroaryl group in "substituted or unsubstituted heteroaryl group", it is the same as the substituent of the aryl group in "substituted or unsubstituted aryl group".

[0126] 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 Preferably, each independently is a hydrogen atom or -X 10 -R 10 .

[0127] R 1 ~R 8 At least one of them is -X 10 -R 10 . Preferably, R 1 ~R 8One or both of them is / are -X 10 -R 10 , more preferably R 5 ~R 8 One or both of them is / are -X 10 -R 10 , further preferably R 5 and R 7 One or both of them is / are -X 10 -R 10 .

[0128] In one embodiment, preferably R 1 ~R 8 One or two of them is / are -X 10 -R 10 , and the others of R 1 ~R 8 are hydrogen atoms, more preferably R 5 ~R 8 One or two of them is / are -X 10 -R 10 , and the others of R 1 ~R 8 are hydrogen atoms, further preferably R 5 and R 7 One or two of them is / are -X 10 -R 10 , and the others of R 1 ~R 8 are hydrogen atoms.

[0129] X 9 Each independently represents a single bond, -NR 9’ -, -O-, -S-, -CO-, -SO 2 -, -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.

[0130] 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.

[0131] X 10 Each independently represents a single bond, -(substituted or unsubstituted alkylene)-, -NH-, -O-, -S-, -CO-, -SO 2 -, -NHCO-, -CONH-, -OCO- or -COO-. X10 Preferably a single bond.

[0132] R 10 Each independently represents a substituted or unsubstituted aryl group, or a substituted or unsubstituted heteroaryl group. R 10 Preferably a substituted or unsubstituted aryl group.

[0133] In one embodiment, the diamine compound represented by formula (D-1) is preferably the compound represented by the following formula (D-2), and more preferably the compound represented by the following formula (D-3) (4-aminobenzoic acid 5-amino-1,1'-biphenyl-2-yl (alias: (5-amino-2-biphenyl)-4-aminobenzoate, PHBAAB)). [Chemical formula 3] (In the formula, R 1 ~R 6 and R 8 Each independently represents a hydrogen atom, a halogen atom, a cyano group, a nitro group, -X 9 -R 9 , and other symbols are the same as those in formula (D-1).) [Chemical formula 4]

[0134] In another embodiment, specific examples of the diamine compound include 4,4'-diamino-2,2'-bis(trifluoromethyl)-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-fluorenylene)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]]dianiline (BPPAN), etc. Preferred are 4,4'-(m-phenylenediisopropylidene)dianiline and 4,4'-[1,4-phenylenebis[(1-methylethylidene)-4,1-phenyleneoxy]]dianiline. It should be noted that 4,4'-(m-phenylenediisopropylidene)dianiline (Bisaniline-M) is the compound represented by the following formula (I), and 4,4'-[1,4-phenylenebis[(1-methylethylidene)-4,1-phenyleneoxy]]dianiline (BPPAN) is the compound represented by the following formula (II). [Chemical formula 5]

[0135] In one embodiment, the diamine compound for preparing the polyimide resin preferably contains 4,4'-(m-phenylene diisopropylidene) diphenylamine (the compound shown in the above formula (I)), more preferably contains 4,4'-(m-phenylene diisopropylidene) diphenylamine and the diamine compound shown in formula (D-1) in combination, further preferably contains 4,4'-(m-phenylene diisopropylidene) diphenylamine and the diamine compound shown in formula (D-2) in combination, and even more preferably further contains (5-amino-2-biphenyl)-4-aminobenzoate (the compound shown in the above formula (D-3)) in combination.

[0136] When the diamine compound for preparing the polyimide resin contains 4,4'-(m-phenylene diisopropylidene) diphenylamine, the content of the structure derived from 4,4'-(m-phenylene diisopropylidene) diphenylamine is preferably 10 mol% or more, more preferably 30 mol% or more, further preferably 50 mol% or more, and even more preferably 60 mol% or more, based on 100 mol% of all the structures of the diamine compound constituting the polyimide resin.

[0137] The diamine compound can be a commercially available compound or a compound synthesized by a known method. For example, the diamine compound shown in formula (D-1) can be synthesized by the synthesis method described in Japanese Patent No. 6240798 or a method based thereon. The diamine compound can be used alone or in combination of two or more.

[0138] The acid anhydride for preparing the polyimide resin is not particularly limited, and in a preferred embodiment, it is an aromatic tetracarboxylic dianhydride. Examples of the aromatic tetracarboxylic dianhydride include pyromellitic dianhydride, naphthalene tetracarboxylic dianhydride, anthracene tetracarboxylic dianhydride, bis(phthalic anhydride), etc., and bis(phthalic anhydride) is preferred.

[0139] Pyromellitic dianhydride refers to the dianhydride of benzene having 4 carboxyl groups, and further, the benzene ring therein may optionally have 1 to 3 substituents. Here, as the substituent, it is preferably selected from a halogen atom, a cyano group, and -X 13 -R 13 (the same as the definition of the following formula (D-4)). Specific examples of pyromellitic dianhydride include pyromellitic dianhydride, 1,2,3,4-benzenetetracarboxylic dianhydride, etc.

[0140] Naphthalene tetracarboxylic dianhydride refers to the dianhydride of naphthalene having 4 carboxyl groups, and further, the naphthalene ring therein may optionally have 1 to 3 substituents. Here, as the substituent, it is preferably selected from a halogen atom, a cyano group, and -X 13 -R 13 (the same as the definition of the following formula (D-4)). Specific examples of naphthalene tetracarboxylic dianhydride include 1,4,5,8-naphthalenetetracarboxylic dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, etc.

[0141] Anthracene tetracarboxylic dianhydride refers to the dianhydride of anthracene having 4 carboxyl groups. Further, the anthracene ring therein may optionally have 1 to 3 substituents. Here, as the substituent, it is preferably selected from a halogen atom, a cyano group, and -X 13 -R 13 (same as the definition of the following formula (D-4)). As anthracene tetracarboxylic dianhydride, 2,3,6,7-anthracene tetracarboxylic dianhydride etc. can be specifically cited.

[0142] Bis(phthalic anhydride) refers to a compound containing 2 phthalic anhydrides in the molecule. Further, the 2 benzene rings in the 2 phthalic anhydrides may each optionally have 1 to 3 substituents. Here, as the substituent, it is preferably selected from a halogen atom, a cyano group, and -X 13 -R 13 (same as the definition of the following formula (D-4)). The two phthalic anhydrides in bis(phthalic anhydride) may be directly bonded, or bonded via a linking structure having 1 to 100 backbone atoms selected from carbon atoms, oxygen atoms, sulfur atoms, and nitrogen atoms.

[0143] As bis(phthalic anhydride), a compound represented by the formula (D-4) can be cited, for example. [Chemical formula 6] (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 , X 13 each independently represent a single bond, -NR 13’ -, -O-, -S-, -CO-, -SO 2 -, -NR 13’ CO-, -CONR 13’ (, -OCO-, or -COO-, R 13 each independently represent a substituted or unsubstituted alkyl group, or a substituted or unsubstituted alkenyl group, R 13 ' each independently represent a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted alkenyl group, Y represents a single bond, or a linking 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 of 0 to 3.)

[0144] Y is preferably a linking structure having 1 to 100 backbone atoms selected from carbon atoms, oxygen atoms, sulfur atoms, and nitrogen atoms. n1 and m1 are preferably 0.

[0145] The "linking structure" in Y has 1 to 100 skeletal atoms selected from carbon atoms, oxygen atoms, sulfur atoms, and nitrogen atoms. The "linking structure" is preferably -[A-Ph] a -A-[Ph-A] b -[wherein, A independently represents a single bond, -(substituted or unsubstituted alkylene)-, -O-, -S-, -CO-, -SO 2 -, -CONH-, -NHCO-, -COO-, or -OCO-, and a and b independently represent integers from 0 to 2 (preferably 0 or 1)]-shown divalent group.

[0146] Specific examples of the "linking structure" in Y include -CH 2 -, -CH 2 CH 2 -, -CH 2 CH 2 CH 2 -, -CH 2 CH 2 CH 2 CH 2 -, -CH 2 CH 2 CH 2 CH 2 CH 2 -, -CH(CH 3 )-, -C(CH 3 ) 2 -, -O-, -CO-, -SO 2 -, -Ph-, -O-Ph-O-, -O-Ph-SO 2 -Ph-O-, -O-Ph-C(CH 3 ) 2 -Ph-O-, etc., preferably -O-Ph-C(CH 3 ) 2 -Ph-O-.

[0147] As the bisphthalic anhydride, specifically, 3,3',4,4'-benzophenonetetracarboxylic dianhydride, 3,3',4,4'-diphenylethertetracarboxylic dianhydride, 3,3',4,4'-diphenylsulfonetetracarboxylic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 2,2',3,3'-biphenyltetracarboxylic dianhydride, 2,3,3',4'-biphenyltetracarboxylic dianhydride, 2,3,3',4'-benzophenonetetracarboxylic dianhydride, 2,3,3',4'-diphenylethertetracarboxylic dianhydride, 2,3,3',4'-diphenylsulfonetetracarboxylic dianhydride, 2,2'-bis(3,4-dicarboxyphenoxyphenyl)sulfone dianhydride, methylene-4,4'-bisphthalic dianhydride, 1,1-ethylidene-4,4'-bisphthalic dianhydride, 2,2-propylidene-4,4'-bisphthalic dianhydride, 1,2-ethylidene-4,4'-bisphthalic dianhydride, 1,3-propylidene-4,4'-bisphthalic dianhydride, 1,4-butylidene-4,4'-bisphthalic dianhydride, 1,5-pentylidene-4,4'-bisphthalic 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), etc. can be cited.

[0148] In one embodiment, the phthalic acid compound represented by the formula (D-4) is preferably the compound represented by the following formula (D-5), and more preferably the compound represented by the following formula (D-6) (4,4'-(4,4'-isopropylidenediphenoxy)bisphthalic dianhydride: BPADA). [Chemical formula 7] (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 , n1 and m1 each independently represent an integer of 0 to 3, and other symbols are the same as those in the formula (D-4).) [Chemical formula 8]

[0149] The aromatic tetracarboxylic dianhydride can be a commercially available product or a substance synthesized by a known method or a method based thereon. The aromatic tetracarboxylic dianhydride can be used alone in one kind or in combination of two or more kinds.

[0150] In one embodiment, the acid anhydride used for preparing the polyimide resin may contain other acid anhydrides in addition to the aromatic tetracarboxylic dianhydride.

[0151] As other acid anhydrides, specifically, 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 other aliphatic tetracarboxylic dianhydrides can be cited.

[0152] The content of the structure derived from the aromatic tetracarboxylic dianhydride in all the structures of the acid anhydride constituting the polyimide resin is preferably 10 mol% or more, more preferably 30 mol% or more, further preferably 50 mol% or more, further preferably 70 mol% or more, further more preferably 90 mol% or more, and particularly preferably 100 mol%.

[0153] The polyimide resin preferably has a structural unit represented by the following general formula (D). [Chemical formula 9] (In the general formula (D), R 51 each independently represents a single bond or a residue derived from bisphthalic anhydride, and R 52 each independently represents a single bond or a residue derived from a diamine compound.)

[0154] R 51 each independently represents a single bond or a residue derived from bisphthalic anhydride, and is preferably a residue derived from bisphthalic anhydride. The residue derived from bisphthalic anhydride represented by R 51 refers to a divalent group obtained by removing two phthalic anhydrides from bisphthalic anhydride. Regarding bisphthalic anhydride, as described above.

[0155] R 51 The examples of the residue derived from bisphthalic anhydride represented are the same as the examples of the "linking structure" represented by Y in the formula (D-4). R 51The residue derived from the bisphthalic anhydride is preferably a divalent group obtained by removing two phthalic anhydrides from 4,4'-(4,4'-isopropylidenediphenoxy)bisphthalic anhydride (the compound represented by the above formula (D-6)).

[0156] R 52 each independently represents a single bond or a residue derived from a diamine compound, preferably a residue derived from a diamine compound. R 52 The residue derived from the diamine compound is a divalent group obtained by removing two amino groups from the diamine compound. Regarding the diamine compound, as described above.

[0157] R 52 The residue derived from the diamine compound is preferably a divalent group obtained by removing two amino groups from 4,4'-(m-phenyleneisopropylidene)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 (D-1), more preferably a divalent group obtained by removing two amino groups from 4,4'-(m-phenyleneisopropylidene)dianiline, or the diamine compound represented by the formula (D-2), and further preferably a divalent group obtained by removing two amino groups from 4,4'-(m-phenyleneisopropylidene)dianiline, or a divalent group obtained by removing two amino groups from (5-amino-2-biphenyl)-4-aminobenzoate (the compound represented by the above formula (D-3)).

[0158] In one embodiment, the polyimide resin may be a copolymer having a plurality of different structural units represented by the formula (D). In such an embodiment, the polyimide resin preferably has: R in the formula (D) 52 a structural unit that is a divalent group obtained by removing two amino groups from 4,4'-(m-phenyleneisopropylidene)dianiline (the compound represented by the above formula (I)), and R in the formula (D) 52 a structural unit that is a divalent group obtained by removing two amino groups from a diamine compound other than 4,4'-(m-phenyleneisopropylidene)dianiline. As the diamine compound other than 4,4'-(m-phenyleneisopropylidene)dianiline, the diamine compound represented by the formula (D-1) is preferred, the diamine compound represented by the formula (D-2) is more preferred, and (5-amino-2-biphenyl)-4-aminobenzoate (the compound represented by the above formula (D-3)) is further preferred. In a more preferred embodiment, the polyimide resin has: R in the formula (D) 52 a structural unit that is a divalent group obtained by removing two amino groups from 4,4'-(m-phenyleneisopropylidene)dianiline, and R in the formula (D) 52 a structural unit that is a divalent group obtained by removing two amino groups from (5-amino-2-biphenyl)-4-aminobenzoate.

[0159] In one embodiment, the polyimide resin preferably contains a structural unit (hereinafter sometimes referred to as "structural unit D1") obtained by reacting 4,4'-(m-phenylene diisopropylidene) diphenylamine (the compound represented by the above formula (I)) with 4,4'-(4,4'-isopropylidene diphenoxy) bisphthalic anhydride (BPADA: the compound represented by the above formula (D-6)). Further, in the said embodiment, it is more preferable that the polyimide resin, in addition to containing the structural unit D1, also contains a structural unit obtained by reacting (5-amino-2-biphenyl)-4-aminobenzoate (the compound represented by the above formula (D-3)) with 4,4'-(4,4'-isopropylidene diphenoxy) bisphthalic anhydride.

[0160] The polyimide resin as the component (D) can be prepared by a conventionally known method. As a known method, for example, a method of heating a mixture of a diamine compound, an acid anhydride, and a solvent to cause a reaction can be cited. The mixing amount of the diamine compound is, for example, usually 0.5 to 1.5 molar equivalents relative to the acid anhydride, and preferably 0.9 to 1.1 molar equivalents.

[0161] As the solvent used in the preparation of the polyimide resin as the component (D), amide solvents such as N,N-dimethylacetamide, N,N-diethylacetamide, N,N-dimethylformamide, and N-methyl-2-pyrrolidone can be cited; 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, in the preparation of the polyimide resin, an imidization catalyst, an azeotropic dehydration solvent, an acid catalyst, etc. can be used as needed. As the imidization catalyst, for example, tertiary amines such as triethylamine, triisopropylamine, triethylenediamine, N-methylpyrrolidone, N-ethylpyrrolidone, N,N-dimethyl-4-aminopyridine, and pyridine can be cited. As the azeotropic dehydration solvent, for example, toluene, xylene, ethylcyclohexane, etc. can be cited. As the acid catalyst, for example, acetic anhydride, etc. can be cited. If a person skilled in the art, the usage amounts of the imidization catalyst, the azeotropic dehydration solvent, the acid catalyst, etc. can be appropriately set. The reaction temperature for preparing the polyimide resin is usually 100 to 250 °C.

[0162] The weight average molecular weight of the component (D) is preferably 3000 or more, more preferably 5000 or more, further preferably 8000 or more, preferably 200000 or less, more preferably 100000 or less, and further preferably 80000 or less. The Mw of the component (D) can be measured by gel permeation chromatography (GPC) as a value in terms of polystyrene.

[0163] As the content of the component (D), when the non-volatile components in the resin composition layer are set to 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, 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, 1.5% by mass or less.

[0164] When the resin component in the resin composition layer is set to 100% by mass, the content of the component (D) is preferably 0.5% by mass or more, more preferably 1% by mass or more, still more preferably 1.5% by mass or more, preferably 20% by mass or less, more preferably 15% by mass or less, still more preferably 10% by mass or less, 8% by mass or less, 5% by mass or less.

[0165] When the content of the component (A-1) contained in the resin composition layer is set to a1 and the content of the component (D) contained in the resin composition layer is set to d1, a1 / d1 is preferably 0.1 or more, more preferably 1 or more, still more preferably 5 or more, 7 or more, preferably 25 or less, more preferably 20 or less, still more preferably 15 or less, 10 or less. By adjusting the contents of the component (A-1) and the component (D) so that a1 / d1 is within the above range, the effects of the present invention can be significantly obtained.

[0166] The total content of the component (B) and the component (D), when the non-volatile components in the resin composition layer are set to 100% by mass, is preferably 10% by mass or more, more preferably 15% by mass or more, still more preferably 20% by mass or more, 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.

[0167] -(E) Phenoxy resin- The resin composition layer may contain (E) phenoxy resin as the component (E). The (E) phenoxy resin as the component (E) does not contain substances belonging to the above components (A) to (D). By making the resin composition layer contain (E) phenoxy resin, the stress during curing of the resin composition layer can be relaxed, and the film flexibility can also be improved. The component (E) can be used alone in 1 kind, or 2 or more kinds can be used.

[0168] (E) The weight-average molecular weight (Mw) of the phenoxy resin is preferably 5000 or more, more preferably 8000 or more, and further preferably 10000 or more. The upper limit of the Mw is not particularly limited, preferably 100000 or less, more preferably 80000 or less, and further preferably 50000 or less. The Mw of the component (E) can be measured by gel permeation chromatography (GPC) as a value in terms of polystyrene conversion.

[0169] Examples of the (E) phenoxy resin include phenoxy resins having one or more skeletons selected from a bisphenol A skeleton, a bisphenol F skeleton, a bisphenol S skeleton, a bisphenol acetophenone skeleton, a phenolic aldehyde 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 (E) phenoxy resin can be any functional group such as a phenolic hydroxyl group or an epoxy group.

[0170] Examples of commercially available products of the (E) phenoxy resin include "1256" and "4250" (both are phenoxy resins containing a bisphenol A skeleton) manufactured by Mitsubishi Chemical Corporation; "YX8100" (a phenoxy resin containing a bisphenol S skeleton) manufactured by Mitsubishi Chemical Corporation; "YX6954" (a phenoxy resin containing a bisphenol acetophenone skeleton) manufactured by Mitsubishi Chemical Corporation; "FX280" and "FX293" manufactured by Nippon Steel Chemical & Materials Co., Ltd.; "YL7500BH30", "YX6954BH30", "YX7553", "YX7553BH30", "YL7891BH30", "YX7200B35", "YL7769BH30", "YL6794", "YL7213", "YL7290", and "YL7482" manufactured by Mitsubishi Chemical Corporation, etc.

[0171] As the content of the component (E), when the non-volatile content in the resin composition layer is 100% by mass, it is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, further preferably 1% by mass or more, preferably 10% by mass or less, more preferably 5% by mass or less, further preferably 3% by mass or less, and particularly preferably not contained.

[0172] When the resin component in the resin composition layer is 100% by mass, the content of the component (E) is preferably 1% by mass or more, more preferably 2% by mass or more, further preferably 3% by mass or more, preferably 10% by mass or less, more preferably 8% by mass or less, further preferably 5% by mass or less, and particularly preferably not contained.

[0173] -(F) Flame retardant- The resin composition layer may contain a (F) flame retardant as the (F) component. The (F) flame retardant as the (F) component does not contain substances belonging to the above (A) to (E) components. By containing the (F) flame retardant, the (F) flame retardant reacts with the epoxy resin in the (D) component, and the glass transition temperature and flame retardancy of the cured product can be further improved. The (F) component can be used alone as one kind, or two or more kinds can be used in combination.

[0174] Examples of the (F) flame retardant include, for example, phosphazene compounds, organic phosphorus-based flame retardants, organic nitrogen-containing phosphorus compounds, nitrogen compounds, organosilicon-based flame retardants, metal hydroxides, etc., and phosphazene compounds are preferred. The flame retardant can be used alone as one kind, or two or more kinds can be used in combination.

[0175] The phosphazene compound is not particularly limited as long as it is a cyclic compound composed of nitrogen and phosphorus, and the phosphazene compound is preferably a phosphazene compound having phenolic hydroxyl groups.

[0176] 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.

[0177] As the flame retardant other than the phosphazene compound, commercially available products can be used, and examples include "HCA-HQ" manufactured by Mitsuho Corporation, "PX-200" manufactured by Daihachi Chemical Industry Co., Ltd., etc. As the flame retardant, a flame retardant that is difficult to hydrolyze is preferred. For example, 10-(2,5-dihydroxyphenyl)-10H-9-oxa-10-phosphaphenanthrene-10-oxide, etc. are preferred.

[0178] When the non-volatile components in the resin composition layer are set to 100% by mass, the content of the (F) flame retardant is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, further preferably 0.8% by mass or more, preferably 5% by mass or less, more preferably 4% by mass or less, and further preferably 3% by mass or less.

[0179] When the resin components in the resin composition layer are set to 100% by mass, the content of the (F) flame retardant is preferably 1% by mass or more, more preferably 1.5% by mass or more, further preferably 2% by mass or more, preferably 15% by mass or less, more preferably 10% by mass or less, and further preferably 8% by mass or less.

[0180] -(G) Curing accelerator- The resin composition layer may contain a (G) curing accelerator as the component (G). The (G) curing accelerator as the component (G) does not contain substances belonging to the above components (A) to (F). The (G) curing accelerator has a function as a curing catalyst for promoting the curing of the epoxy resin in the component (D).

[0181] As the (G) curing accelerator, a compound that promotes the curing of epoxy resin can be used. Examples of such (G) curing accelerators include, for example, 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 can be used alone as one kind, or two or more kinds can be used in combination.

[0182] Examples of the phosphorus-based curing accelerators include aliphatic phosphonium salts such as tetrabutylphosphonium bromide, tetrabutylphosphonium chloride, tetrabutylphosphonium acetate, tetrabutylphosphonium caprate, tetrabutylphosphonium laurate, bis(tetrabutylphosphonium) pyromellitate, tetrabutylphosphonium hydrogen hexahydrophthalate, tetrabutylphosphonium 2,6-bis[(2-hydroxy-5-methylphenyl)methyl]-4-methylphenolate, and di-tert-butylmethylphosphonium tetraphenylborate; aromatic phosphonium salts such as methyltriphenylphosphonium bromide, ethyltriphenylphosphonium bromide, propyltriphenylphosphonium bromide, butyltriphenylphosphonium bromide, benzyltriphenylphosphonium chloride, tetraphenylphosphonium bromide, p-tolyltriphenylphosphonium tetrakis(p-tolyl)borate, tetraphenylphosphonium tetraphenylborate, tetraphenylphosphonium tetrakis(p-tolyl)borate, triphenylethylphosphonium tetraphenylborate, tris(3-methylphenyl)ethylphosphonium tetraphenylborate, tris(2-methoxyphenyl)ethylphosphonium tetraphenylborate, (4-methylphenyl)triphenylphosphonium thiocyanate, tetraphenylphosphonium thiocyanate, and butyltriphenylphosphonium thiocyanate; aromatic phosphine-borane complexes such as triphenylphosphine-triphenylborane; aromatic phosphine-quinone 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, and tricyclohexylphosphine; and 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, and 2,2'-bis(diphenylphosphino)diphenyl ether, etc.

[0183] 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], etc.

[0184] 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, etc.

[0185] As imidazole-based curing accelerators, for example, 2-methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 1,2-dimethylimidazole, 2-ethyl-4-methylimidazole, 1,2-dimethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 1-benzyl-2-methylimidazole, 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 other imidazole compounds, as well as adducts of imidazole compounds and epoxy resins. As commercially available products of imidazole-based curing accelerators, 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" etc. manufactured by Mitsubishi Chemical Corporation.

[0186] As metal-based curing accelerators, for example, organometallic complexes or organometallic salts of metals such as cobalt, copper, zinc, iron, nickel, manganese, tin, etc. Specific examples of organometallic complexes include organocobalt complexes such as cobalt(II) acetylacetonate, 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; organomanganese complexes such as manganese(II) acetylacetonate, etc. As organometallic salts, for example, zinc octoate, tin octoate, zinc naphthenate, cobalt naphthenate, tin stearate, zinc stearate, etc.

[0187] Examples of the amine-based curing accelerator include trialkylamines such as triethylamine and tributylamine; 4-dimethylaminopyridine, benzyldimethylamine, 2,4,6-tris(dimethylaminomethyl)phenol, 1,8-diazabicyclo(5,4,0)-undecene, and the like. As the amine-based curing accelerator, commercially available products can be used, and examples include "MY-25" manufactured by Ajinomoto Fine-Techno Co., Ltd.

[0188] When the non-volatile content in the resin composition layer is 100% by mass, the content of the (G) curing accelerator is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, further preferably 0.1% by mass or more, preferably 1.5% by mass or less, more preferably 1% by mass or less, and further preferably 0.8% by mass or less.

[0189] When the resin component in the resin composition layer is 100% by mass, the content of the (G) curing accelerator is preferably 0.1% by mass or more, more preferably 0.2% by mass or more, further preferably 0.3% by mass or more, preferably 5% by mass or less, more preferably 3% by mass or less, and further preferably 2% by mass or less.

[0190] -(H) Other additives- The resin composition layer may contain (H) other additives as optional non-volatile components. Examples of the (H) other additives include, for example: elastomers (excluding substances belonging to components (D) and (E)); 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 (bentonite) and montmorillonite; defoaming agents such as silicone-based defoaming agents, acrylic-based defoaming agents, fluorine-based defoaming agents, and vinyl resin-based defoaming agents; ultraviolet absorbers such as benzotriazole-based ultraviolet absorbers; adhesion improvers such as ureidosilanes; 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 ester-based stabilizers, titanate ester-based stabilizers, aluminate ester-based stabilizers, zirconate ester-based stabilizers, isocyanate-based stabilizers, carboxylic acid-based stabilizers, and carboxylic anhydride-based stabilizers; photopolymerization initiator aids such as tertiary amines; photosensitizers such as pyrazolines, anthracenes, coumarins, xanthones, and thioxanthones. The (H) other additives may be used alone or in combination of two or more.

[0191] From the viewpoints of thinning the circuit board and providing a cured product with 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 further preferably 55 μm or less. The lower limit of the thickness of the resin composition layer is not particularly limited and can generally be 5 μm or more, 10 μm or more, etc.

[0192] <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 and the like or the generation of damage on the surface of the resin composition layer.

[0193] Examples of the protective film include, for example, a film formed of a plastic material, a metal foil, and a release paper, and a film formed of a plastic material and a metal foil are preferred.

[0194] When using a film formed of a plastic material as the protective film, examples of the plastic material include polyesters such as polyethylene terephthalate (hereinafter sometimes simply referred to as "PET"), polyethylene naphthalate (hereinafter sometimes simply referred to as "PEN"), polycarbonate (hereinafter sometimes simply referred to as "PC"), acrylic polymers such as polymethyl methacrylate (PMMA), cyclic polyolefins, triacetyl cellulose (TAC), polyether sulfide (PES), polyether ketone, polyimide, etc. Among them, polyethylene terephthalate and polyethylene naphthalate are preferred, and inexpensive polyethylene terephthalate is particularly preferred.

[0195] When using a metal foil as the protective film, examples of the metal foil include copper foil, aluminum foil, etc., and copper foil is preferred. As the copper foil, a foil formed of single metal of copper or a foil formed of an alloy of copper and other metals (such as tin, chromium, silver, magnesium, nickel, zirconium, silicon, titanium, etc.) can be used.

[0196] For the protective film, the surface joined to the resin composition layer can be subjected to matting treatment, corona treatment, antistatic treatment.

[0197] In addition, as the protective film, a protective film with a release layer on the surface joined to the resin composition layer can be used. Examples of the release agent used in the release layer of the protective film with a release layer include one or more release agents selected from alkyd resins, polyolefin resins, polyurethane resins, and silicone resins. The protective film with a release layer can use commercially available products, such as PET films having a release layer mainly composed of an alkyd resin-based release agent, namely "SK-1", "AL-5", "AL-7" manufactured by Lintec Corporation, "Lumirror T60", "Lumirror R80", "Lumirror" manufactured by Toray Industries, Inc.; "Purex" manufactured by Teijin Limited; "Unipeel" manufactured by Unitika Ltd., etc.

[0198] The thickness of the protective film is not particularly limited, for example, it is 1 μm to 40 μm. In the case where the protective film is a multilayer structure such as a protective film with a release layer, it is preferred that the thickness of the entire protective film is within the above range.

[0199] <Manufacturing method of resin sheet with metal foil> Regarding the manufacturing method of the resin sheet with metal foil, for example, a resin varnish in which the components contained in the resin composition layer are dissolved in a solvent is prepared, and this resin varnish is coated on the protective film using a die coater or the like, and then dried to form a resin composition layer on the protective film. Then, by laminating a metal foil on the surface of the resin composition layer using a roll laminator or the like, a resin sheet with metal foil can be manufactured. Regarding the solvent, the above-mentioned solvents can be used.

[0200] Drying can be carried out by known methods such as heating and hot air blowing. The drying conditions are not particularly limited, and drying is carried out so that the content of the (A-1) component after drying is 20% by mass or more when the total amount of the (A) component contained in the resin composition layer is set to 100% by mass.

[0201] Regarding the drying temperature, it is preferably carried out at a temperature lower than the boiling point of the (A-1) component in the resin composition layer. The specific drying temperature is preferably 80°C or higher, more preferably 90°C or higher, further preferably 100°C or higher, 110°C or higher, preferably 150°C or lower, more preferably 140°C or lower, and further preferably 130°C or lower.

[0202] As the drying time, for example, it is preferably 0.5 minutes or more, more preferably 1 minute or more, further preferably 1.5 minutes or more, 2 minutes or more, preferably 10 minutes or less, more preferably 8 minutes or less, and further preferably 5 minutes or less.

[0203] In addition, the weight reduction rate (weight loss rate) of the resin composition layer after heating the resin composition layer at 200°C for 30 minutes is preferably 10% or less, more preferably 9% or less, and further preferably 8% or less. The lower limit is preferably 0.01% or more, more preferably 0.1% by mass or more, and further preferably 0.5% by mass or more, 1% by mass or more. The weight reduction rate can be measured by the method described in the examples below.

[0204] The resin sheet with a metal foil can be wound into a roll for storage. When using the resin sheet with a metal foil, it can be used by peeling off the protective film.

[0205] <Physical properties, etc. of the resin sheet with a metal foil> The resin sheet with a metal foil of the present invention has a resin composition layer containing a specific amount of the (A-1) component, and thus exhibits the characteristic of a high glass transition temperature (Tg) of the cured product of the resin composition layer thermally cured by vacuum pressing treatment. The glass transition temperature of the cured product of the resin composition layer thermally cured by vacuum pressing treatment is preferably 150°C or higher, more preferably 155°C or higher, and further preferably 160°C or higher. The upper limit of the glass transition temperature of the cured product is not particularly limited and can be 300°C or lower, etc. The glass transition temperature can be measured by the method described in the examples below.

[0206] The resin composition layer in the resin sheet with a metal foil of the present invention exhibits excellent thin-film flexibility due to the resin composition layer containing a specific amount of component (A-1). Therefore, a resin sheet with a metal foil having excellent operability is provided. Specifically, the resin sheet with a metal foil is cut by a temporary assembly device, and cracks and notches at the end of the cut edge are visually confirmed. As a result, there are no cracks or notches in the resin sheet with a metal foil. The evaluation of thin-film flexibility can be measured by the method described in the examples below.

[0207] The resin composition layer in the resin sheet with a metal foil of the present invention generally exhibits excellent adhesiveness. Therefore, a resin sheet with a metal foil having excellent operability is provided. Specifically, the adhesive force (peeling force) of the resin composition layer is measured using a probe tack tester. As a result, it is preferably less than 0.6 N, more preferably 0.4 N or less, and further preferably less than 0.4 N. The lower limit is not particularly limited and can be 0.01 N or more, etc. The evaluation of adhesiveness can be measured by the method described in the examples below.

[0208] The resin sheet with a metal foil of the present invention generally exhibits excellent mechanical strength due to the high glass transition temperature (Tg) of the cured product of the resin composition layer. Therefore, an insulating layer with excellent mechanical strength is provided. The resin sheet with a metal foil from which the protective film has been peeled is laminated such that the resin composition layer is in contact with the copper foil. After lamination, the resin composition layer is thermally cured by vacuum pressing treatment, and the copper foil is removed to obtain a cured product for evaluation. Then, the cured product for evaluation is cut into test pieces with a width of 2 mm and a length of 80 mm, and the elongation at break is measured using a tensile testing machine. At this time, the elongation at break is preferably 3.0% or more, more preferably 4.0% or more, and further preferably 5.0% or more. The upper limit is not particularly limited and can be 10% or less, etc. The measurement of mechanical strength can be measured by the method described in the examples below.

[0209] The resin sheet with a metal foil of the present invention generally exhibits a low dielectric loss tangent of the cured product of the resin composition layer. 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, further preferably 0.008 or less, or 0.005 or less. The lower limit is not particularly limited and 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.

[0210] The resin sheet with a metal foil of the present invention can provide a cured product having a high glass transition temperature, excellent film flexibility, and mechanical strength. Therefore, for the resin sheet with a metal foil of the present invention, in the manufacture of a circuit board, it can be suitably used as a resin sheet (for forming an insulating layer and a conductor layer) for forming these two layers; in the manufacture of a circuit board, it can be suitably used as a resin sheet (for forming an insulating layer and a conductor layer using a vacuum pressing process) for forming these two layers by a vacuum pressing process; in the manufacture of a printed wiring board, it can be suitably used as a resin sheet (for forming an insulating layer and a conductor layer) for forming these two layers; in the manufacture of a printed wiring board, it can be suitably used as a resin sheet (for forming an insulating layer and a conductor layer using a vacuum pressing process) for forming these two layers by a vacuum pressing process.

[0211] [Circuit board] The circuit board of the present invention can be manufactured using the resin sheet with a metal foil of the present invention. That is, a circuit board can be provided that includes an insulating layer formed from a cured product of a resin composition layer of the resin sheet with a metal foil of the present invention, and a conductor layer formed from a metal foil.

[0212] Examples of the circuit board include a printed wiring board, a semiconductor chip package, etc. The circuit board includes an insulating layer formed from a cured product of a resin composition layer of the resin sheet with a metal foil of the present invention, and a conductor layer formed from a metal foil.

[0213] The circuit board can be manufactured, for example, using the above-mentioned resin sheet with a metal foil by a method including the following steps (I) and (II). (I) A step of laminating the resin composition layer in the resin sheet with a metal foil on an inner layer substrate by a vacuum pressing process; (II) A step of thermally curing the resin composition layer to form an insulating layer.

[0214] The "inner layer substrate" used in step (I) refers to a component of the substrate that becomes the circuit board, and 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. In addition, the substrate may have a conductor layer on one or both sides thereof, and the conductor layer can be patterned. An inner layer substrate having a conductor layer (circuit) formed on one or both sides of the substrate is sometimes referred to as an "inner layer circuit board". In addition, in the manufacture of a circuit board, an intermediate product to which an insulating layer and / or a conductor layer is to be further formed is also included in the "inner layer substrate" as referred to in the present invention. When the circuit board is a component-embedded circuit board, an inner layer substrate with components embedded therein can be used.

[0215] Regarding the lamination of the inner substrate and the resin sheet with a metal foil, after peeling off the protective film, the resin composition layer of the resin sheet with a metal foil is laminated to the inner substrate by a vacuum pressing process.

[0216] First, peel off the protective film of the resin sheet with a metal foil, and assemble the inner substrate and the resin sheet with a metal foil from which the protective film has been peeled off into a vacuum pressing device in such a manner that the resin composition layer of the resin sheet with a metal foil is joined to the inner substrate. Next, perform a vacuum pressing process of thermocompression bonding the inner substrate and the resin composition layer under reduced pressure conditions.

[0217] The inner substrate and the resin sheet with a metal foil from which the protective film has been peeled off may also be assembled into a vacuum pressing device via a buffer paper, a metal plate such as a stainless steel plate (SUS plate), a release film, or the like.

[0218] The vacuum pressing process can be carried out using a conventionally known vacuum pressing device, in which the inner substrate and the resin sheet with a metal foil from which the protective film has been peeled off are pressed from both sides thereof using a heated metal plate such as a SUS plate. As a commercially available vacuum pressing device, for example, "VH1-1603" manufactured by Kitakawa Seiki Co., Ltd. can be cited.

[0219] The vacuum pressing process can be carried out only once, or can be repeated two or more times. In the case of repeating two or more times, the crimping pressure, heating temperature, pressing time, etc. can be the same or different.

[0220] In the vacuum pressing process, 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, preferably 50 kgf / cm 2 or less, more preferably 35 kgf / cm 2 or less, still more preferably 25 kgf / cm 2 or less.

[0221] In the vacuum pressing process, the pressure of the atmosphere, that is, the pressure (degree of decompression) during decompression in the chamber that houses the laminated structure of the objects to be processed, is preferably 3×10 -2 MPa or less, more preferably 1×10 -2 MPa or less. There is no particular limitation on the lower limit, and it can be 1×10 -10 MPa or more, etc.

[0222] In the vacuum pressing process, the heating temperature also varies depending on the composition of the resin composition layer, preferably being 80 °C or higher, more preferably 90 °C or higher, and further preferably 100 °C or higher. The upper limit of the heating temperature is not particularly limited and can generally be 300 °C or lower, etc. It should be noted that through the heating in the vacuum pressing process, the resin composition layer can be thermally cured to form an insulating layer.

[0223] In the vacuum pressing process, the pressing time is preferably 5 minutes or longer, more preferably 10 minutes or longer, and further preferably 15 minutes or longer. The upper limit is not particularly limited, preferably being 300 minutes or shorter, more preferably 200 minutes or shorter, and further preferably 150 minutes or shorter.

[0224] After laminating the resin sheet with a metal foil from which the protective film has been peeled off on the inner layer substrate through the vacuum pressing process, in step (II), the resin composition layer is thermally cured to form an insulating layer. As a method for thermally curing the resin composition layer, for example, in the case of performing a pressing process through the vacuum pressing process, a method of thermally curing the resin composition layer using the heat during pressing to form an insulating layer can be cited.

[0225] The thermal curing conditions of the resin composition layer are not particularly limited, and the conditions generally adopted when forming the insulating layer of a circuit board and a printed wiring board can be used.

[0226] For example, the thermal curing conditions of the resin composition layer also vary depending on the type of the resin composition layer, etc. The curing temperature is preferably 120 °C to 240 °C, more preferably 150 °C to 220 °C, and further preferably 170 °C to 210 °C. The curing time can preferably be 5 minutes to 120 minutes, more preferably 10 minutes to 100 minutes, and further preferably 15 minutes to 100 minutes.

[0227] Before thermally curing the resin composition layer, the resin composition layer can be preheated at a temperature lower than the curing temperature. For example, before thermally curing the resin composition layer, 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), the resin composition layer can be preheated for 5 minutes or longer (preferably 5 minutes to 150 minutes, more preferably 15 minutes to 120 minutes, and further preferably 15 minutes to 100 minutes).

[0228] Since the resin sheet with a metal foil used in the present invention contains a metal foil, as step (III), it can include a step of forming a conductor layer (circuit) by a subtractive method or a modified semi-additive method.

[0229] In step (III), the metal foil in the resin sheet with a metal foil can be used to form a conductor layer by a subtractive method or a modified semi-additive method.

[0230] In the subtractive method, unnecessary portions (non-circuit forming portions) of the metal foil are selectively removed, such as by etching, to form a circuit. Circuit formation using the subtractive method can be carried out according to well-known steps. For example, circuit formation using the subtractive method can be carried out by a method including the following steps: i) providing a resist layer 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 resist layer to form a wiring pattern; iii) etching and removing the exposed metal foil portion; and iv) removing the resist layer.

[0231] In the improved semi-additive method, the non-circuit forming portions of the metal foil are protected by an anti-plating layer. After thickening a metal such as copper by electrolytic plating on the circuit forming portions, the anti-plating layer is removed, and the metal foil except for the circuit forming portions is removed by etching to form a circuit. Circuit formation using the improved semi-additive method can be carried out according to well-known steps. For example, circuit formation using the improved semi-additive method can be carried out by a method including the following steps: i) providing an anti-plating layer 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 anti-plating layer to form a wiring pattern; iii) performing electrolytic plating through the anti-plating layer; iv) removing the anti-plating layer; and v) etching and removing the metal foil except for the circuit forming portions. It should be noted that in the case where the metal foil is thick, before the above step i), the entire surface of the metal foil can be thinned by etching or the like so that the metal foil becomes a desired thickness (usually 5 μm or less, 4 μm or less, or 3 μm or less).

[0232] When manufacturing a circuit board, a step (IV) of opening holes and a step (V) of roughening the insulating layer can be further carried out. These steps (IV) to step (V) can be carried out according to various methods well-known to those skilled in the art used in the manufacture of circuit boards. In addition, if necessary, the formation of the insulating layer and the conductor layer in steps (I) to (V) can be repeatedly carried out to form a multilayer wiring board.

[0233] [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 or a printed wiring board.

[0234] Examples of the semiconductor device include various semiconductor devices used in electrical products (such as computers, mobile phones, digital cameras, and televisions, etc.) and transportation means (such as motorcycles, automobiles, trams, ships, and airplanes, etc.).

[0235] 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 portions" refer to "the portions in the circuit board that transmit electrical signals", and their positions can be on the surface or buried portions. In addition, the semiconductor chips are not particularly limited as long as they are circuit elements made of semiconductors.

[0236] The method of mounting semiconductor chips when manufacturing a semiconductor device is not particularly limited as long as the semiconductor chips function effectively. Specifically, examples include wire bonding mounting methods, flip chip mounting methods, mounting methods based on built-in non-protruding and non-recessed layers (BBUL), mounting methods based on anisotropic conductive films (ACF), mounting methods based on non-conductive films (NCF), and the like. Here, the "mounting method based on built-in non-protruding and non-recessed layers (BBUL)" refers to "a mounting method in which a semiconductor chip is directly buried in a recess of a circuit board and the semiconductor chip is connected to the wiring on the circuit board". Examples

[0237] Hereinafter, the present invention will be specifically described by way of examples. The present invention is not limited to these examples. It should be noted that in the following, "parts" and "%" respectively refer to "parts by mass" and "% by mass" unless otherwise specified.

[0238] <Synthesis Example 1: Synthesis of Polyimide 1> Into a 1000 ml detachable flask equipped with a nitrogen inlet tube and a stirring device, 62.46 g (120 mmol) of 4,4'-(4,4'-isopropylidenediphenoxy)diphthalic anhydride (BPADA), 12.17 g (40 mmol) of (5-amino-2-biphenyl)-4-aminobenzoate (PHBAAB), 27.56 g (80 mmol) of 4,4'-(m-phenyleneisopropylidene)dianiline (Bisaniline-M), 303 g of γ-butyrolactone (GBL), 1.90 g (24 mmol) of pyridine, and 34 g of toluene were charged. Under a nitrogen atmosphere, the reaction was carried out at 180 °C for 10 hours while removing toluene out of the system halfway, thereby obtaining a GBL solution containing 25% by mass of polyimide resin 1 as a non-volatile component.

[0239] <Synthesis Example 2: Synthesis of Polyimide 2> In 400 g of cyclohexanone (hereinafter also referred to as "Anone") as a solvent, 49.6 g of 4,4'-(4,4'-isopropylidenediphenoxy) bisphthalic anhydride (BPADA), 50.4 g of 4,4'-[1,4-phenylenebis[(1-methylethylidene)-4,1-phenyleneoxy]] bisaniline (BPPAN), and 40 g of toluene as a solvent were mixed, and the resulting monomer composition was stirred and reacted at room temperature and atmospheric pressure for 3 hours. Thus, a polyamide solution was obtained.

[0240] Next, after raising the temperature of the polyamide solution, while maintaining it at about 160 °C, the condensed water and toluene were removed azeotropically under a nitrogen stream. It was confirmed that a specified amount of water had accumulated in the water quantitative receiver and that no water was flowing out. After confirmation, the reaction solution was heated again and stirred at 200 °C for 1 hour. Then, it was cooled. Thus, a cyclohexanone solution containing 20% by mass of polyimide resin 2 as a non-volatile component was obtained.

[0241] Based on the above reaction path, it is speculated that polyimide resin 2 contains a structural unit represented by the following formula (a). In addition, based on the above reaction path, it is speculated that polyimide resin 2 contains a skeleton derived from BPADA and a skeleton derived from BPPAN. [Chemical formula 10]

[0242] <Synthesis Example 3: Synthesis of Maleimide A> A MEK solution (non-volatile component: 62% by mass) of a maleimide compound synthesized by the method described in Synthesis Example 1 of Japanese Invention Association Publication Bulletin Public Technology No. 2020-500211 was prepared. This maleimide compound has a structure represented by the following formula (1) (Mw / Mn = 1.81, t” = 1.47 (mainly 1, 2, or 3). [Chemical formula 11]

[0243] <Manufacture of Resin Varnish> Each component was weighed in the parts by mass shown in Table 1 below and uniformly dispersed using a high-speed rotary mixer to obtain a resin varnish. It should be noted that in Table 1 below, the parts by mass of component (A-1) and component (A-2) are the parts by mass obtained by adding the amounts of component (A-1) and component (A-2) contained in each component used as component (B) to component (G). In addition, in Table 1 below, the parts by mass of component (B) to component (G) are the parts by mass of the non-volatile component. [Table 1] (Table 1) *1: Represents the content when the non-volatile components contained in the resin varnish are set to 100% by mass. *2: Represents the content when the non-volatile components in the resin composition layer are set to 100% by mass. *3: Represents the content when the whole of component (A) contained in the resin composition layer is set to 100% by mass.

[0244] The details of each component described in the table are as follows. (A-1) Organic solvents with a boiling point of 180 °C or higher · DMSO: Dimethyl sulfoxide, boiling point 189 °C · NMP: N-Methyl-2-pyrrolidone, boiling point 202 °C · GBL: γ-Butyrolactone, boiling point 204 °C · IP150: Ipzole, boiling point 184 - 205 °C, manufactured by Idemitsu Kosan Co., Ltd. (A-2) Organic solvents with a boiling point less than 180 °C · MEK: Methyl ethyl ketone, boiling point 79 °C · Toluene: Boiling point 110 °C · PGM: Propylene glycol monomethyl ether, boiling point 120 °C · DMAc: N,N-Dimethylacetamide · Anone: Cyclohexanone: Boiling point 155 °C (B) Thermosetting resin · NC-3000-L: Biphenyl type epoxy resin, functional group equivalent 269 g / eq., manufactured by Nippon Kayaku Co., Ltd. · ZX-1059: 1:1 mixture of bisphenol A type epoxy resin and bisphenol F type epoxy resin, functional group equivalent 169 g / eq., manufactured by Nippon Steel Chemical & Material Co., Ltd. · 630: Aminophenol type epoxy compound, equivalent 98 g / eq., manufactured by Mitsubishi Chemical Corporation · LA-7054: Phenolic curing agent having a triazine skeleton and a linear phenolic resin structure, functional group equivalent 125 g / eq., MEK solution with 60% by mass of non-volatile components, manufactured by DIC Corporation · P-d: Benzoxazine compound, functional group equivalent 217 g / eq., manufactured by Shikoku Kasei Kogyo Co., Ltd. · HPC-8000-65T: Active ester resin containing a dicyclopentadiene type diphenol structure, functional group equivalent 223 g / eq., toluene solution with 65% by mass of non-volatile components, manufactured by DIC Corporation · V03: Carbodiimide based curing agent, functional group equivalent 216 g / eq., toluene solution with 50% by mass of non-volatile components, manufactured by Nisshinbo Chemical Inc. · OPE-2St: Vinylbenzyl-modified polyphenylene ether, functional group equivalent weight 590 g / eq., manufactured by Mitsubishi Gas Chemical Company · Maleimide A: Maleimide synthesized in Synthesis Example 3 · A-DOG: Polyfunctional acrylate, functional group equivalent weight 163 g / eq., manufactured by Shin-Nakamura Chemical Co., Ltd. (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 diameter 0.5 μm, specific surface area 5.8 m 2 / g, manufactured by Admatechs Co., Ltd. (D) Flexible resin · Polyimide 1: Polyimide synthesized in Synthesis Example 1 · Polyimide 2: Polyimide synthesized in Synthesis Example 2 (E) Phenoxy resin · YX7553BH30: Phenoxy resin, 1:1 solution of MEK and cyclohexanone with a non-volatile content of 30% by mass, manufactured by Mitsubishi Chemical Corporation (F) Flame retardant · HCA-HQ-HST: Phosphorus-containing phenolic flame retardant, manufactured by Mitsuwa Corporation (G) Curing accelerator · 1B2PZ: Manufactured by Shikoku Kasei Kogyo Co., Ltd.

[0245] <Production of resin sheet with metal foil> Using a die coater, the resin varnishes obtained in the examples and comparative examples were coated on the release surface of a release-treated polyethylene terephthalate film (Toray Industries, Inc. “Lumirror R80, thickness 38 μm) as a support so that the thickness of the resin composition layer became 40 μm, and dried according to the drying conditions described in the above table. Next, using a roll laminator (manufactured by Daishin Laminator Co., Ltd., “FIRST LAMINATOR VA-770H”), a copper foil with a carrier (manufactured by Mitsui Mining & Smelting Co., Ltd. “MicroThin MT18Ex”, 3-μm-thick ultra-thin copper foil / 18-μm-thick carrier copper foil) having a carrier copper foil and an ultra-thin copper foil was bonded to the surface of the resin composition layer under the conditions of a roll pressure of 0.25 MPa, a conveyance speed of 0.3 m / min, and a roll temperature of 90 °C to obtain a resin sheet with a metal foil.

[0246] <Measurement of content rate (residual solvent amount) of organic solvent in resin composition layer> Measure 5 mg of a part of the resin composition layer from the resin sheets with metal foils prepared in the examples and comparative examples, and treat the measured samples under oven conditions of 250 °C for 10 minutes using a GCMS-QP2020-NX (manufactured by Shimadzu Corporation). Perform measurements under conditions of a sample line temperature of 260 °C, a transfer line temperature of 260 °C, and a cycle time of 55 minutes. Determine the solvent types based on the detected peaks, and compare with a pre-made standard curve to analyze the types and contents of the organic solvents contained in the resin composition layer of the resin sheets with metal foils.

[0247] <Measurement of weight reduction rate> Cut the resin sheets with metal foils prepared in the examples and comparative examples into 10 cm × 10 cm, place them together with sufficiently dried silica gel in a desiccator, and leave for 30 minutes. Then, measure the mass (g) of the metal foil resin sheet and set its value as α1 (g). Next, heat the metal foil resin sheet in an oven at 200 °C for 30 minutes, cool it in the desiccator with silica gel in the same manner as before for 30 minutes, and then measure the mass (g) of the metal foil resin sheet again and set its value as α2 (g). In addition, cut only the metal foil into 10 cm × 10 cm, place it in the desiccator for 30 minutes, measure the mass (g) of the metal foil, and set its value as β (g). Calculate the value of the weight reduction rate α (%) of the resin composition layer when the metal foil resin sheet is heat-treated at 200 °C for 30 minutes using the following formula (A). [Mathematical formula 1]

[0248] <Evaluation of film flexibility> Cut the resin sheets with metal foils using a temporary assembly device, and visually confirm cracks and notches at the cut edge ends. Then, evaluate the resin notches based on the following evaluation criteria. 〇: There are no cracks or notches in the resin sheets with metal foils. ×: There are cracks or notches in the resin sheets with metal foils.

[0249] <Evaluation of adhesiveness> Measure the adhesive force using a probe-type initial adhesiveness tester with a thermostat (manufactured by TESTER Sangyo Co., Ltd., TE-6002). Bring a 5 mmφ cylindrical probe made of SUS into contact with the resin sheet with metal foil placed statically in a thermostat at 25 °C at a contact speed of 0.5 cm / second, and after maintaining for 1 second under a load of 1000 gf / cm 2 measure the peel force when pulling the probe at 0.5 cm / second as the probe adhesiveness (adhesive force). Perform 3 measurements for one sample, calculate the average value in each measurement, and evaluate according to the following criteria. 〇: The peel strength is less than 0.4 N △: The peel strength is 0.4 N or more and less than 0.6 N ×: The peel strength is 0.6 N or more.

[0250] <Production of a cured product for evaluation based on vacuum pressing and curing> The resin sheet with a metal foil obtained from the examples and comparative examples was peeled from the support, and another copper foil ("MicroThin MT18Ex" manufactured by Mitsui Mining & Smelting Co., Ltd.) was overlapped so as to be in contact with the resin composition layer. Using a vacuum hot press (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 , as the heating condition, the first-stage pressing was at a temperature of 100 °C for 30 minutes, and the second-stage pressing was at a temperature of 190 °C for 120 minutes to thermally cure the resin composition layer. The resin sheet with a metal foil after thermal curing was immersed in an aqueous solution of iron(II) chloride (manufactured by Tsurumi Soda Co., Ltd., Baume degree 40), the copper foil was removed, and then dried at 130 °C for 15 minutes to obtain a sheet-like cured product. The obtained cured product was called "a cured product for evaluation based on vacuum pressing and curing".

[0251] <Measurement of the dielectric constant / dissipation factor of a cured product for evaluation based on vacuum pressing and curing> The cured product for evaluation based on vacuum pressing and curing was cut into test pieces with a width of 2 mm and a length of 80 mm. For this test piece, using "HP8362B" manufactured by Agilent Technologies, the dissipation factor was measured at a measurement frequency of 5.8 GHz and a measurement temperature of 23 °C by the resonant cavity perturbation method. Two test pieces were measured and the average value was calculated.

[0252] <Measurement of the glass transition temperature of a cured product for evaluation based on vacuum pressing and curing> The cured product for evaluation based on vacuum pressing and curing was cut into test pieces with a width of about 5 mm and a length of about 15 mm, and thermomechanical analysis was performed using a dynamic viscoelasticity measuring device (EXSTAR6000, manufactured by SII Nanotechnology Inc.) by the tensile load method. After mounting the test piece on the above device, the measurement was performed under the measurement conditions of a load of 200 mN and a heating rate of 2 °C / minute. The peak of the obtained tanδ was calculated as the glass transition temperature (°C) and evaluated according to the following criteria. 〇: The glass transition temperature is 160 °C or more △: The glass transition temperature is 150 °C or more and less than 160 °C ×: The glass transition temperature is less than 150 °C.

[0253] <Measurement of Mechanical Strength of Cured Product for Evaluation Based on Vacuum Pressing Curing> Using the tensile testing machine “RTC-1250A” manufactured by Orientec, the tensile strength of the cured product for evaluation based on vacuum pressing curing was measured, and the elongation at break at 23°C was measured. The measurement was carried out in accordance with JIS K 7127. Five measurements were made, and the average values of the top three from top to bottom were calculated and evaluated according to the following criteria. 〇: Elongation at break is 5.0% or more △: Elongation at break is 3.0% or more and less than 5.0% ×: Elongation at break is less than 3.0%.

[0254] [Table 2] (Table 2)

[0255] It was confirmed that the resin composition layers in Examples 1 to 12 contained either a carbodiimide resin or a polyimide resin, and thus the adhesion to the metal foil was also excellent.

Claims

1. A resin sheet with metal foil, comprising a metal foil, a resin composition layer and a protective film in this order, The resin composition layer comprises (A) an organic solvent, (B) a thermosetting resin and (C) an inorganic filler. The component (A) comprises (A-1) an organic solvent having a boiling point of 180° C. or higher, When the entire amount of the component (A) contained in the resin composition layer is 100% by mass, the content of the component (A-1) is 20% by mass or more.

2. The resin sheet with metal foil according to claim 1, wherein Further comprising (D) a flexible resin.

3. The resin sheet with metal foil according to claim 2, wherein (D) The component contains a polyimide resin.

4. The resin sheet with metal foil according to claim 2, wherein When the content of the component (A-1) contained in the resin composition layer is a1 and the content of the component (D) contained in the resin composition layer is d1, a1 / d1 is 0.1 or more and 25 or less.

5. The resin sheet with metal foil according to claim 1, wherein The boiling point of the component (A-1) is 250°C or lower.

6. The resin sheet with metal foil according to claim 1, wherein The component (A-1) contains any of a carbon-oxygen double bond and a carbon-sulfur double bond.

7. The resin sheet with metal foil according to claim 1, wherein The component (A-1) contains a lactam-based organic solvent.

8. The resin sheet with metal foil according to claim 1, wherein The component (A-1) contains γ-butyrolactone.

9. The resin sheet with metal foil according to claim 1, which is used to form an insulating layer and a conductor layer by vacuum pressing.

10. The resin sheet with metal foil according to claim 1, wherein The metal foil is copper foil.

11. A circuit substrate, comprising: An insulating layer formed by a cured product of a resin composition layer of a resin sheet with metal foil according to any one of claims 1 to 10, and A conductor layer formed using the metal foil of the resin sheet with metal foil according to any one of claims 1 to 10. 12 . A semiconductor device comprising the circuit substrate according to claim 11 .

13. A method for manufacturing a circuit substrate, the method comprising: (I) a step of laminating the resin composition layer in the resin sheet with metal foil according to any one of claims 1 to 10 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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