Resin sheet with metal foil

Abstract

To provide a resin sheet with a metal foil capable of giving a cured product having a high glass transition temperature and excellent film flexibility.SOLUTION: A resin sheet with a metal foil includes a metal foil, a resin composition layer, and a protective film in this order. The resin composition layer contains (A) an organic solvent, (B) a thermosetting resin, and (C) an inorganic filler. The component (A) contains (A-1) an organic solvent having a boiling point of 180°C or higher. The content of the component (A-1) is 20 mass% or more based on 100 mass% of the whole component (A) contained in the resin composition layer.SELECTED DRAWING: None

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 resins having excellent heat resistance and insulation properties have been used for insulating layers such as circuit boards (see, for example, Patent Documents 1 and 2).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

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

[0005] However, in the above method, during the vacuum press treatment, the resin composition layer is sandwiched between the inner layer substrate and the metal foil. Therefore, when the resin composition layer is thermally cured, the organic solvent contained in the resin composition layer cannot smoothly escape from the resin composition layer. For this reason, the curing of the resin composition layer may not proceed sufficiently, and the glass transition temperature of the insulating layer may be lowered.

[0006] 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, when the amount of the organic solvent is reduced, the flexibility of the resin composition layer is impaired, and cracks and chips may occur in the resin composition layer of the resin sheet with metal foil. Hereinafter, the property of having high flexibility of the resin composition layer and being able to suppress cracks and chips in the resin composition layer may be referred to as "film flexibility".

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

[0008] The present invention has been devised in view of the above problems, and an object thereof is to provide a resin sheet with 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 metal foil; a semiconductor device including the circuit board; and a method for manufacturing a circuit board.

Means for Solving the Problems

[0009] As a result of intensive studies by the present inventors, a resin sheet with metal foil including a metal foil, a resin composition layer, and a protective film in this order, wherein 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, the present invention has been completed by finding that a cured product having a high glass transition temperature and excellent film flexibility can be obtained.

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

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

[10] . A semiconductor device including the circuit board described in

[11] .

[13] (I) A step of laminating the resin composition layer in the resin sheet with metal foil according to any one of [1] to

[10] on the inner layer substrate by vacuum pressing, and (II) A method for manufacturing a circuit board, including a step of thermosetting the resin composition layer to form an insulating layer.

Effect of the Invention

[0011] According to the present invention, it is possible to provide a resin sheet with metal foil that can obtain a cured product having a high glass transition temperature and excellent film flexibility; a circuit board manufactured using the resin sheet with metal foil, a semiconductor device including the circuit board, and a method for manufacturing a circuit board.

Embodiments for Carrying Out the Invention

[0012] Hereinafter, the present invention will be described in detail with reference to embodiments and examples. However, the present invention is not limited to the embodiments and examples described below, and can be arbitrarily modified and implemented without departing from the scope of the claims of the present invention and its equivalent scope.

[0013] [Resin Sheet with Metal Foil] The resin sheet with metal foil of the present invention is a resin sheet with metal foil including a metal foil, a resin composition layer, and a protective film in this order, and the resin composition layer includes (A) an organic solvent, (B) a thermosetting resin, and (C) an inorganic filler. The (A) component includes (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 100% by mass. Such a resin sheet with metal foil can obtain a cured product having a high glass transition temperature and excellent film flexibility. In addition, the resin sheet with metal foil usually has excellent tackiness, a low dielectric tangent, and can also obtain a cured product having excellent elongation at break.

[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 may be formed from the metal foil. At this time, the conductor layer may be formed by the entire metal foil or a part of the metal foil.

[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 made of single metal of copper may be used, or a foil made of an alloy of copper and other metals (for example, tin, chromium, silver, magnesium, nickel, zirconium, silicon, titanium, etc.) may be used.

[0016] The metal foil may have a single-layer structure or a multilayer structure in which two or more single metal layers or alloy layers made of different types of metals or alloys are laminated. Examples of the metal foil having a multilayer structure include a metal foil including a carrier metal foil and an ultra-thin metal foil joined to the carrier metal foil. Such a metal foil having a multilayer structure may include a release layer between the carrier metal foil and the ultra-thin metal foil to make the ultra-thin metal foil peelable from the carrier metal foil. The release layer is not particularly limited as long as the ultra-thin metal foil can be peeled from the carrier metal foil, and examples thereof include an alloy layer of an element selected from the group consisting of Cr, Ni, Co, Fe, Mo, Ti, W, and P; an organic film, etc. In addition, when using a metal foil having a multilayer structure, the resin composition layer is provided on the ultra-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 still more preferably 2 μm or more. The upper limit is not particularly limited, but is preferably 35 μm or less, more preferably 25 μm or less, and still more preferably 15 μm or less. When the metal foil has a multilayer structure, it is preferable that the total thickness of the metal foil is within such a range, and the thickness of the ultra-thin metal foil among them may 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 in contact with the resin composition layer of the metal foil is preferably 300 nm or more, preferably 350 nm or more, more preferably 400 nm or more, and still more preferably 500 nm or more from the viewpoint of improving the adhesion with the resin composition layer. The upper limit is not particularly limited, but is preferably 1000 nm or less, more preferably 900 nm or less, and still more preferably 800 nm or less. The arithmetic mean roughness (Ra) is a value measured in accordance with ISO 25178 and can be measured using a non-contact surface roughness meter. Examples of the non-contact surface roughness meter include "WYKO NT3300" manufactured by Veeco Instruments Inc.

[0019] Commercially available products may be used for the metal foil. Examples of commercially available products of the metal foil include "Microsin MT18Ex", "Microsin MT18FL", "3EC-III", "3EC-M3-VLP", "3EC-M2S-VLP" manufactured by Mitsui Mining & Smelting Co., Ltd., "JDLC", "JTCSLC", "HA-V2", "HA", "HG" manufactured by JX Metals, "CF-TX4-SV", "V9", "HD", "FLEQ HD", "FUTF", "RCF-T4X", "RCF-T5B", etc. manufactured by Fukuda Metal Foil Powder Industry Co., Ltd.

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

[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. Usually, 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 usually has a single-layer structure, but may have a two-layer or more structure as long as the effects of the present invention are not impaired.

[0022] The resin composition layer contains (A) an organic solvent, (A-1) an organic solvent having a boiling point of 180 °C or higher, (B) a thermosetting resin, and (C) an inorganic filler. Further, the resin composition layer may optionally contain (A-2) an organic solvent having a boiling point of 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, the content of each component in the resin composition layer is a value when the non-volatile components in the resin composition layer are 100% by mass, unless otherwise specified. Further, in the present invention, the non-volatile components mean all components excluding the solvent in the resin composition layer. Further, in the present invention, the resin component in the resin composition layer represents the component excluding (C) the inorganic filler among the non-volatile components of the resin composition layer.

[0024] In the present invention, the boiling point represents the boiling point under atmospheric pressure (760 mmHg) unless otherwise specified.

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

[0026] The (A) component may optionally contain, in addition to the (A-1) component, (A-2) an organic solvent having a boiling point of less than 180 °C. The (A-1) component and the (A-2) component may be used alone or in combination of two or more.

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

[0028] The content (residual solvent amount) of component (A-1) is 20% by mass or more, preferably 25% by mass or more, more preferably 30% by mass or more, still more 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 when the total amount of component (A) contained in the resin composition layer is 100% by mass. The upper limit is preferably 100% by mass or less, more preferably 95% by mass or less, still more preferably 90% by mass or less, 85% by mass or less, 80% by mass or less. By adjusting the content of component (A-1) so as to be within such a range and incorporating component (A-1) into the resin composition layer, it becomes possible to obtain a cured product having a high glass transition temperature and excellent film flexibility. The content of component (A-1) represents the residual solvent amount contained in the resin composition layer in the resin sheet with a metal foil. The residual solvent amount can be measured by the method described in the examples below.

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

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

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

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

[0033] Specific examples of the component (A-1) include, for example, sulfur atom-containing organic solvents 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 ethyl diglycol acetate; petroleum-based organic solvents such as petroleum ether, petroleum naphtha, hydrogenated petroleum naphtha, solvent naphtha, and Isopar 150. Among them, the component (A-1) preferably contains either a sulfur atom-containing organic solvent, a lactone-based organic solvent, or a lactam-based organic solvent, and more preferably contains 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 taken as 100% by mass, the content of the component (A-1) is preferably 5% by mass or more, more preferably 5.5% by mass or more, and still more preferably 6% by mass or more. The upper limit is preferably 10% by mass or less, more preferably 8% by mass or less, and still more preferably 7% by mass or less. As described above, the non-volatile components mean all the components excluding the solvent in the resin composition layer.

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

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

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

[0038] Specific examples of the (A-2) component 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, ethyl diglycol 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] 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, still more 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, still more preferably 5% by mass or more, 10% by mass or more, when the total amount of component (A) contained in the resin composition layer is 100% by mass. The residual solvent amount can be measured by the method described in the examples below.

[0040] 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, still more preferably 1% by mass or less, when all components contained in the resin composition layer are 100% by mass. The lower limit is not particularly limited and can be 0.01% by mass or more, etc.

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

[0042] -(B) Thermosetting resin- The resin composition layer contains a (B) thermosetting resin as component (B). The (B) thermosetting resin as this component (B) excludes those corresponding to 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 may be used alone or in combination of two or more.

[0043] (B) Examples of the thermosetting resin include epoxy resins, polyphenylene ether resins, radically polymerizable resins, phenol resins, cyanate resins, active ester resins, carbodiimide resins, acid anhydride resins, amine resins, benzoxazine resins, and thiol resins. The thermosetting resin may be used alone or in combination of two or more kinds.

[0044] (B) From the viewpoint of significantly obtaining the effects of the present invention, the 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 may be hereinafter referred to as a "curing agent". Examples of the curing agent include, for example, phenol resins, cyanate resins, active ester resins, carbodiimide resins, acid anhydride resins, amine resins, benzoxazine resins, and thiol resins. As the curing agent, carbodiimide resins, phenol resins, and active ester resins are preferable, 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 preferable. The curing agent may be used alone or in combination of two or more kinds. As one embodiment, the thermosetting resin contains an epoxy resin, a carbodiimide resin, and a phenol resin.

[0045] Epoxy resin is a thermosetting resin having an epoxy group. Examples of epoxy resins include tetramethyl bisphenol type epoxy resin, biphenyl type epoxy resin, naphthalene type epoxy resin, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, bisphenol AF type epoxy resin, dicyclopentadiene type epoxy resin, tris phenol type epoxy resin, naphthol novolak type epoxy resin, phenol novolak type epoxy resin, tert-butyl-catechol type epoxy resin, naphthol type epoxy resin, anthracene type epoxy resin, glycidyl amine type epoxy resin, glycidyl ester type epoxy resin, cresol novolak type epoxy resin, phenol aralkyl type epoxy resin, linear aliphatic epoxy resin, epoxy resin having a butadiene structure, alicyclic epoxy resin, heterocyclic epoxy resin, spiro ring-containing epoxy resin, cyclohexane type epoxy resin, cyclohexanedimethanol type epoxy resin, naphthylene ether type epoxy resin, trimethylol type epoxy resin, tetraphenylethane type epoxy resin, isocyanurate type epoxy resin, phenolphthalimide type epoxy resin, etc. The epoxy resin may be used alone or in combination of two or more kinds.

[0046] (B) The thermosetting resin preferably contains, as the epoxy resin, an epoxy resin having two or more epoxy groups in one molecule. The proportion of the epoxy resin having two or more epoxy groups in one molecule is preferably 50% by mass or more, more preferably 60% by mass or more, particularly preferably 70% by mass or more, and usually 100% by mass or less, based on 100% by mass of the epoxy resin.

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

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

[0049] Preferred liquid epoxy resins include bisphenol A type epoxy resins, bisphenol F type epoxy resins, bisphenol AF type epoxy resins, naphthalene type epoxy resins, glycidyl ester type epoxy resins, glycidyl amine type epoxy resins, phenol novolac type epoxy resins, alicyclic epoxy resins having an ester skeleton, cyclohexane type epoxy resins, cyclohexanedimethanol type epoxy resins, and epoxy resins having a butadiene structure. More preferred are glycidyl amine type epoxy resins, bisphenol A type epoxy resins, and bisphenol F type epoxy resins, and even more preferred are bisphenol A type epoxy resins and bisphenol F type epoxy resins.

[0050] Specific examples of the liquid epoxy resin include "HP4032", "HP4032D", "HP4032SS" (naphthalene-type epoxy resin) manufactured by DIC Corporation; "828US", "828EL", "jER828EL", "825", "Epicoat 828EL" (bisphenol A-type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "jER807", "1750" (bisphenol F-type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "jER152" (phenol novolak-type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "630", "630LSD", "604" (glycidylamine-type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "ED-523T" (glycerol-type epoxy resin) manufactured by ADEKA Corporation; "EP-3950L", "EP-3980S" (glycidylamine-type epoxy resin) manufactured by ADEKA Corporation; "EP-4088S" (dicyclopentadiene-type epoxy resin) manufactured by ADEKA Corporation; "ZX1059" (a mixture of bisphenol A-type epoxy resin and bisphenol F-type epoxy resin) manufactured by Nippon Steel Chemical & Material Co., Ltd.; "EX-721" (glycidyl ester-type epoxy resin) manufactured by Nagase ChemteX Corporation; "Celoxide 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., and the like. These may be used alone or in combination of two or more.

[0051] As the solid epoxy resin, a solid epoxy resin having three or more epoxy groups in one molecule is preferable, and an aromatic solid epoxy resin having three or more epoxy groups in one molecule is more preferable.

[0052] Examples of the solid epoxy resin include tetramethyl bisphenol type epoxy resin (bixylenol type epoxy resin), naphthalene type epoxy resin, naphthalene type tetrafunctional epoxy resin, naphthol novolak type epoxy resin, cresol novolak type epoxy resin, dicyclopentadiene type epoxy resin, tris phenol type epoxy resin, naphthol type epoxy resin, biphenyl type epoxy resin, naphthylene ether type epoxy resin, anthracene type epoxy resin, bisphenol A type epoxy resin, bisphenol AF type epoxy resin, phenol aralkyl type epoxy resin, tetraphenylethane type epoxy resin, and phenol phthalimide type epoxy resin. Among them, bixylenol type epoxy resin and biphenyl type epoxy resin are preferred, and bixylenol type epoxy resin and biphenyl type epoxy resin are more preferred.

[0053] Specific examples of the solid epoxy resin include "HP4032H" (naphthalene-type epoxy resin) manufactured by DIC Corporation; "HP-4700" and "HP-4710" (naphthalene-type tetrafunctional epoxy resin) manufactured by DIC Corporation; "N-690" (cresol novolak-type epoxy resin) manufactured by DIC Corporation; "N-695" (cresol novolak-type epoxy resin) manufactured by DIC Corporation; "HP-7200", "HP-7200HH", "HP-7200H", and "HP-7200L" (dicyclopentadiene-type epoxy resin) manufactured by DIC Corporation; "EXA-7311", "EXA-7311-G3", "EXA-7311-G4", "EXA-7311-G4S", and "HP6000" (naphthylene ether-type epoxy resin) manufactured by DIC Corporation; "EPPN-502H" (trisphenol-type epoxy resin) manufactured by Nippon Kayaku Co., Ltd.; "NC7000L" (naphthol novolak-type epoxy resin) manufactured by Nippon Kayaku Co., Ltd.; "NC3000H", "NC3000", "NC3000L", "NC3000FH", and "NC3100" (biphenyl-type epoxy resin) manufactured by Nippon Kayaku Co., Ltd.; "ESN475V" and "ESN4100V" (naphthalene-type epoxy resin) manufactured by Nippon Steel Chemical & Material Co., Ltd.; "ESN485" (naphthol-type epoxy resin) manufactured by Nippon Steel Chemical & Material Co., Ltd.; "ESN375" (dihydroxynaphthalene-type epoxy resin) manufactured by Nippon Steel Chemical & Material Co., Ltd.; "YX4000H", "YX4000", "YX4000HK", and "YL7890" (bixylenol-type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "YL6121" (biphenyl-type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "YX8800" (anthracene-type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "YX7700" (phenol aralkyl-type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "PG-100" and "CG-500" manufactured by Osaka Gas Chemical Co., Ltd.; "YX7760" (bisphenol AF-type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "YL7800" (fluorene-type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "jER1010" (bisphenol A-type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "jER1031S" (tetraphenylethane-type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "WHR991S" (phenolphthalimide-type epoxy resin) manufactured by Nippon Kayaku Co., Ltd., and the like.These may be used alone or in combination of two or more kinds.

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

[0056] The weight average molecular weight (Mw) of the epoxy resin is preferably 100 to 5,000, more preferably 250 to 3,000, and still more preferably 400 to 1,500. The weight average molecular weight of the resin can be measured as a value in terms of polystyrene by the gel permeation chromatography (GPC) method.

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

[0058] (B) When the content of the epoxy resin as the thermosetting resin is based on 100% by mass of the resin components in the resin composition layer, it is preferably 30% by mass or more, more preferably 35% by mass or more, and particularly preferably 40% by mass or more, and is 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 component (B) include "NORYL SA90" manufactured by SABIC. The polyphenylene ether resin may have one or more (preferably two or more) styryl groups or vinylphenyl groups in one molecule. Examples of such polyphenylene ether resins include, in addition to styrene monomer, "OPE-2St", "OPE-2St 1200", "OPE-2St 2200" (all manufactured by Mitsubishi Gas Chemical Company).

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

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

[0062] The type of the radical polymerizable resin as component (B) is not particularly limited as long as it has one or more (preferably two or more) radical polymerizable unsaturated groups in one molecule. Examples of the radical polymerizable resin include resins having one or more selected from maleimide group, vinyl group, allyl group, styryl group, vinylphenyl group, acryloyl group, methacryloyl group, fumaroyl group, and maleoyl group as the radical polymerizable unsaturated group. Among them, from the viewpoint of significantly obtaining the effects of the present invention, the radical polymerizable resin is preferably a maleimide resin.

[0063] As long as the maleimide resin has one or more (preferably two or more) maleimide groups (2,5-dihydro-2,5-dioxo-1H-pyrrol-1-yl groups) in one molecule, its type is not particularly limited. Examples of the maleimide resin include (1) maleimide resins containing an aliphatic skeleton (preferably an aliphatic skeleton with 36 carbon atoms derived from dimer diamine), such as "BMI-3000J", "BMI-5000", "BMI-1400", "BMI-1500", "BMI-1700", "BMI-689" (all manufactured by Designer Molecules Inc.), "SLK6895-T90" (manufactured by Shin-Etsu Chemical Co., Ltd.); (2) maleimide resins containing an indane skeleton described in JP-A No. 2020-500211 of the Japan Institute of Invention and Innovation; (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.), "BMI-80" (manufactured by KAI Chemical Co., Ltd.).

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

[0065] (B) When the non-volatile components in the resin composition layer are 100% by mass, the content of the radical-polymerizable resin as the thermosetting resin is preferably 0.5% by mass or more, more preferably 1% by mass or more, still more preferably 1.5% by mass or more, and preferably 10% by mass or less, more preferably 5% by mass or less, still more preferably 3% by mass or less.

[0066] (B) When the content of the radically polymerizable resin as the thermosetting resin is based on 100% by mass of the resin components in the resin composition layer, it is preferably 1% by mass or more, more preferably 2% by mass or more, still more preferably 3% by mass or more, and preferably 15% by mass or less, more preferably 12% by mass or less, still more 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. Since the phenol resin can react with the epoxy resin to cure the resin composition layer when combined with the epoxy resin, it is sometimes referred to as a "phenolic curing agent". From the viewpoint of obtaining the effects of the present invention remarkably, a phenol resin having a novolac structure is preferable. Further, from the viewpoint of adhesion, a nitrogen-containing phenol resin is preferable, and a triazine skeleton-containing phenol resin is more preferable. Among them, from the viewpoint of obtaining the effects of the present invention remarkably, a triazine skeleton-containing phenol novolac resin is preferable. Specific examples of the phenol resin include, for example, "MEH-7700", "MEH-7810", "MEH-7851" manufactured by Meiwa Kasei Co., Ltd., "NHN", "CBN", "GPH" manufactured by Nippon Kayaku Co., Ltd., "SN-170", "SN-180", "SN-190", "SN-475", "SN-485", "SN-495", "SN-375", "SN-395" manufactured by Nippon Steel Chemical & Material Co., Ltd., "LA-7052", "LA-7054", "LA-3018", "LA-3018-50P", "LA-1356", "TD2090", "TD-2090-60M", "KA-1163" manufactured by DIC Corporation, etc.

[0068] As the active ester resin, compounds having two or more highly reactive ester groups in one molecule, such as phenol esters, thiophenol esters, N-hydroxyamine esters, esters of heterocyclic hydroxy compounds, etc., are generally preferably used. Since the active ester resin can react with the epoxy resin to cure the resin composition layer when combined with the epoxy resin, it is sometimes referred to as an "active ester-based curing agent". The active ester resin is preferably obtained by a condensation reaction of a carboxylic acid compound and / or a thiocarboxylic acid compound with a hydroxy compound and / or a thiol compound. Particularly from the viewpoint of improving the high-temperature reflow bulge resistance, an active ester resin obtained from a carboxylic acid compound and a hydroxy compound is preferred, and an active ester resin obtained from a carboxylic acid compound and a phenol compound and / or a naphthol compound is more preferred. Examples of the carboxylic acid compound include benzoic acid, acetic acid, succinic acid, maleic acid, itaconic acid, phthalic acid, isophthalic acid, terephthalic acid, pyromellitic acid, etc. Examples of the phenol compound or naphthol compound include hydroquinone, resorcin, bisphenol A, bisphenol F, bisphenol S, phenolphthalein, methylated bisphenol A, methylated bisphenol F, methylated bisphenol S, phenol, o-cresol, m-cresol, p-cresol, catechol, α-naphthol, β-naphthol, 1,5-dihydroxynaphthalene, 1,6-dihydroxynaphthalene, 2,6-dihydroxynaphthalene, dihydroxybenzophenone, trihydroxybenzophenone, tetrahydroxybenzophenone, phloroglucin, benzenetriol, dicyclopentadiene-type diphenol compounds, phenol novolac, 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 phenol novolak, and an active ester resin containing a benzoylated product of phenol novolak are preferable. Among them, it is more preferable that it is at least one selected from a dicyclopentadiene-type active ester resin and a naphthalene-type active ester resin. As the dicyclopentadiene-type active ester resin, an active ester resin containing a dicyclopentadiene-type diphenol structure is preferable.

[0070] Examples of commercially available products of the active ester resin include, for example, as the active ester resin containing a dicyclopentadiene-type diphenol structure, "EXB9451", "EXB9460", "EXB9460S", "EXB-8000L", "EXB-8000L-65M", "EXB-8000L-65TM", "HPC-8000L-65TM", "HPC-8000L-65T", "HPC-8000", "HPC-8000-65T", "EXB-8000H" (manufactured by DIC Corporation); as the active ester resin containing a naphthalene structure, "EXB-8100L-65T", "EXB-8150-60T", "EXB-8150-62T", "EXB-9416-70BK", "HPC-8150-62T", "EXB-8" (manufactured by DIC Corporation); as the phosphorus-containing active ester resin, "EXB9401" (manufactured by DIC Corporation); as the active ester resin which is an acetylated product of phenol novolak, "DC808" (manufactured by Mitsubishi Chemical Corporation); as the active ester resin which is a benzoylated product of phenol novolak, "YLH1026", "YLH1030", "YLH1048" (manufactured by Mitsubishi Chemical Corporation); as the active ester resin containing a styryl group and a naphthalene structure, "PC1300-02-65MA" (manufactured by Air Water Inc.), and the like.

[0071] As the cyanate resin, a compound having one or more, preferably two or more cyanate groups in one molecule can be used. Since the cyanate resin can react with an epoxy resin to cure the resin composition layer when combined with the epoxy resin, it is sometimes referred to as a "cyanate-based curing agent". Examples of the cyanate resin include bifunctional cyanate resins such as bisphenol A dicyanate, polyphenol cyanate (oligo(3-methylene-1,5-phenylene cyanate)), 4,4'-methylenebis(2,6-dimethylphenyl cyanate), 4,4'-ethylidenebis(phenyl dicyanate), hexafluorobisphenol A dicyanate, 2,2-bis(4-cyanate)phenylpropane, 1,1-bis(4-cyanatephenylmethane), bis(4-cyanate-3,5-dimethylphenyl)methane, 1,3-bis(4-cyanatephenyl-1-(methylethylidene))benzene, bis(4-cyanatephenyl)thioether, and bis(4-cyanatephenyl)ether; polyfunctional cyanate resins derived from phenol novolac and cresol novolac; prepolymers in which some of these cyanate resins are partially triazine-ized, and the like. Specific examples of the cyanate resin include "PT30" and "PT60" (both are phenol novolac type polyfunctional cyanate resins), "BA230", "BA230S75" (a prepolymer in which part or all of bisphenol A dicyanate is triazine-ized to form a trimer), etc. manufactured by arxada.

[0072] As the carbodiimide resin, a compound having one or more, preferably two or more carbodiimide structures in one molecule can be used. Since the carbodiimide resin can react with an epoxy resin to cure the resin composition layer when combined with the epoxy resin, it is sometimes referred to as a "carbodiimide-based curing agent". Specific examples of the carbodiimide resin include aliphatic biscarbodiimides such as tetramethylene-bis(t-butylcarbodiimide) and cyclohexane bis(methylene-t-butylcarbodiimide); biscarbodiimides such as aromatic biscarbodiimides like phenylene-bis(xilylcarbodiimide); aliphatic polycarbodiimides such as polyhexamethylene carbodiimide, polytrimethylhexamethylene carbodiimide, polycyclohexylene carbodiimide, poly(methylenebiscyclohexylene carbodiimide), and poly(isophorone carbodiimide); aromatic polycarbodiimides such as poly(phenylene carbodiimide), poly(naphthylene carbodiimide), poly(tolylene carbodiimide), poly(methyldiisopropylphenylene carbodiimide), poly(triethylphenylene carbodiimide), poly(diethylphenylene carbodiimide), poly(triisopropylphenylene carbodiimide), poly(diisopropylphenylene carbodiimide), poly(xylene carbodiimide), poly(tetramethylxylene carbodiimide), poly(methylenediphenylene carbodiimide), and poly[methylenebis(methylphenylene) carbodiimide]. Commercially available products of the carbodiimide resin include, for example, "Carbodilite V-02B", "Carbodilite V-03", "Carbodilite V-04K", "Carbodilite V-07", and "Carbodilite V-09" manufactured by Nisshinbo Chemical Inc.; "Stabaxol P", "Stabaxol P400", "Hycadil 510", etc. manufactured by LANXESS 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. Since the acid anhydride resin can react with an epoxy resin to cure the resin composition layer when combined with an epoxy group, it is sometimes referred to as an "acid anhydride-based curing agent". Specific examples of the acid anhydride resin include phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, methyl nadic anhydride, hydrogenated methyl nadic anhydride, trialkyltetrahydrophthalic anhydride, dodecenyl succinic anhydride, 5-(2,5-dioxotetrahydro-3-furanyl)-3-methyl-3-cyclohexene-1,2-dicarboxylic anhydride, trimellitic anhydride, pyromellitic anhydride, benzophenone tetracarboxylic dianhydride, biphenyltetracarboxylic dianhydride, naphthalene tetracarboxylic 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(anhydrotrimellitate), and polymer-type acid anhydrides such as a styrene-maleic acid resin obtained by copolymerizing styrene and maleic acid. Commercially available products of the acid anhydride resin include, for example, "HNA-100", "MH-700", "MTA-15", "DDSA", "OSA" manufactured by Shin Nippon Rika Co., Ltd.; "YH-306", "YH-307" manufactured by Mitsubishi Chemical Corporation; "HN-2200", "HN-5500" manufactured by Resonaak Co., Ltd.; "EF-30", "EF-40", "EF-60", "EF-80" manufactured by Cray Valley Co., Ltd., and the like.

[0074] As the amine resin, a compound having one or more, preferably two or more amino groups in one molecule can be used. Since the amine resin can react with the epoxy resin when combined with an epoxy group to cure the resin composition layer, it is sometimes referred to as an "amine-based curing agent". Examples of the amine resin include aliphatic amines, polyether amines, alicyclic amines, aromatic amines, etc. Among them, aromatic amines are preferred. The amine resin is preferably a primary amine or a secondary amine, and more preferably a primary amine. Specific examples of the amine resin include 4,4'-methylenebis(2,6-dimethylaniline), 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenyl sulfone, 3,3'-diaminodiphenyl sulfone, m-phenylenediamine, m-xylylenediamine, diethyltoluenediamine, 4,4'-diaminodiphenyl ether, 3,3'-dimethyl-4,4'-diaminobiphenyl, 2,2'-dimethyl-4,4'-diaminobiphenyl, 3,3'-dihydroxybenzidine, 2,2-bis(3-amino-4-hydroxyphenyl)propane, 3,3-dimethyl-5,5-diethyl-4,4-diphenylmethanediamine, 2,2-bis(4-aminophenyl)propane, 2,2-bis(4-(4-aminophenoxy)phenyl)propane, 1,3-bis(3-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, 1,4-bis(4-aminophenoxy)benzene, 4,4'-bis(4-aminophenoxy)biphenyl, bis(4-(4-aminophenoxy)phenyl)sulfone, bis(4-(3-aminophenoxy)phenyl)sulfone, etc. Commercially available products of the amine resin include, for example, "SEIKACURE-S" manufactured by Seika Corporation; "KAYABOND C-200S", "KAYABOND C-100", "KAYAHARD A-A", "KAYAHARD A-B", "KAYAHARD A-S" manufactured by Nippon Kayaku Co., Ltd.; "EPICURE W" manufactured by Mitsubishi Chemical Corporation; "DTDA" manufactured by Sumitomo Seika Chemicals Co., Ltd., etc.

[0075] Since benzoxazine resin can react with an epoxy resin to cure the resin composition layer when combined with the epoxy resin, it is sometimes referred to as a "benzoxazine-based curing agent". Specific examples of benzoxazine resin include "JBZ-OP100D" and "ODA-BOZ" manufactured by JFE Chemical Corporation; "HFB2006M" manufactured by Showa Highpolymer Co., Ltd.; "P-d" and "F-a" manufactured by Shikoku Kasei Kogyo Co., Ltd., etc.

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

[0077] The active group equivalent of the curing agent is preferably 50 g / eq. to 3000 g / eq., more preferably 100 g / eq. to 1000 g / eq., still more preferably 100 g / eq. to 500 g / eq., and particularly preferably 100 g / eq. to 300 g / eq. The active group equivalent is the mass of the curing agent per equivalent of the active group.

[0078] The weight average molecular weight (Mw) of the curing agent is preferably 100 to 5,000, more preferably 250 to 3,000, and still more preferably 400 to 1,500. The weight average molecular weight of the resin can be measured as a value in terms of polystyrene by the gel permeation chromatography (GPC) method.

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

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

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

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

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

[0084] -(C) Inorganic filler- The resin composition layer contains an inorganic filler as component (C). By using the resin composition layer containing component (C), a cured product with a low dielectric tangent can be obtained. The (C) inorganic filler may be used alone or in combination of two or more kinds at an arbitrary 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. As the material of the (C) inorganic filler, for example, silica, alumina, glass, cordierite, silicon oxide, barium sulfate, barium carbonate, talc, clay, mica powder, zinc oxide, hydrotalcite, boehmite, aluminum hydroxide, magnesium hydroxide, calcium carbonate, magnesium carbonate, magnesium oxide, boron nitride, aluminum nitride, manganese nitride, aluminum borate, strontium carbonate, strontium titanate, calcium titanate, magnesium titanate, bismuth titanate, titanium oxide, zirconium oxide, barium titanate, barium zirconate titanate, barium zirconate, calcium zirconate, zirconium phosphate, and zirconium tungstate phosphate, etc. are mentioned. Among these, silica is particularly preferable. As silica, for example, amorphous silica, fused silica, crystalline silica, synthetic silica, hollow silica, etc. are mentioned. Also, spherical silica is preferable as silica.

[0086] (C) Examples of commercially available products of the inorganic filler include "SP60-05", "SP507-05" manufactured by Nippon Steel Chemical & Material Co., Ltd.; "YC100C", "YA050C", "YA050C-MJE", "YA010C", "SC2500SQ", "SO-C4", "SO-C2", "SO-C1" manufactured by Admatechs Co., Ltd.; "UFP-30", "DAW-03", "FB-105FD" manufactured by Denka Co., Ltd.; "Silfill NSS-3N", "Silfill NSS-4N", "Silfill NSS-5N" manufactured by Tokuyama Corporation; "Cellspheres", "MGH-005" manufactured by Taiheiyo Cement Corporation; and the like.

[0087] (C) The average particle size of the inorganic filler is not particularly limited, but is preferably 10 μm or less, more preferably 5 μm or less, still more preferably 3 μm or less, even more preferably 2 μm or less, and particularly preferably 1.5 μm or less. The lower limit of the average particle size of the (C) inorganic filler is not particularly limited, but is preferably 0.01 μm or more, more preferably 0.05 μm or more, still more preferably 0.1 μm or more, and particularly preferably 0.2 μm or more. The average particle size of the (C) inorganic filler can be measured by a laser diffraction / scattering method based on the Mie scattering theory. Specifically, it can be measured by creating a volume-based particle size distribution of the inorganic filler with a laser diffraction / scattering type particle size distribution measuring device and taking the median diameter thereof as the average particle size. As the measurement sample, 100 mg of the inorganic filler and 10 g of methyl ethyl ketone can be weighed into a vial and dispersed by ultrasonic waves for 10 minutes. The measurement sample is measured for the volume-based particle size distribution of the inorganic filler using a laser diffraction type particle size distribution measuring device with the light source wavelengths being blue and red and in a flow cell method, and the average particle size is calculated as the median diameter from the obtained particle size distribution. Examples of the laser diffraction type particle size distribution measuring device include "LA-960" manufactured by Horiba, Ltd.

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

[0089] (C) From the viewpoint of enhancing moisture resistance and dispersibility, the inorganic filler is preferably treated with a surface treatment agent. Examples of the surface treatment agent include fluorine-containing silane coupling agents, aminosilane-based coupling agents, epoxysilane-based coupling agents, mercaptosilane-based coupling agents, silane-based coupling agents, alkoxysilanes, organosilazane compounds, titanate-based coupling agents, and the like. Further, the surface treatment agent may be used alone or in any combination of two or more kinds.

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

[0091] From the viewpoint of improving the dispersibility of the inorganic filler, the degree of surface treatment with the surface treatment agent preferably falls within a predetermined range. Specifically, 100% by mass of the inorganic filler is preferably surface-treated with 0.2% to 5% by mass of the surface treatment agent, more preferably surface-treated with 0.2% to 3% by mass, and even more preferably surface-treated with 0.3% to 2% by mass.

[0092] The degree of surface treatment with the surface treatment agent can be evaluated by the amount of carbon per unit surface area of the inorganic filler. The amount of carbon per unit surface area of the inorganic filler is preferably 0.02 mg / m 2 or more, more preferably 0.1 mg / m 2 or more, and even more preferably 0.2 mg / m 2 or more, from the viewpoint of improving the dispersibility of the inorganic filler. On the other hand, from the viewpoint of preventing an increase in the melt viscosity of the resin composition layer and the melt viscosity in the sheet form, the amount of carbon per unit surface area of the inorganic filler is preferably 1.0 mg / m 2 or less, more preferably 0.8 mg / m 2 or less, and even more preferably 0.5 mg / m 2 or less.

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

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

[0095] (C) The inorganic filler is preferably uniformly dispersed and contained in the resin composition layer. 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 the inorganic filler (C) contained in the resin composition layer in the region where the distance from the boundary between the metal foil and the resin composition layer is from 0 μm to 15 μm is preferably within the above-mentioned range, and the content of the inorganic filler (C) contained in the resin composition layer in the region where the distance exceeds 15 μm and reaches the surface of the resin composition layer opposite to the surface joined to the metal foil is also preferably within the above-mentioned range.

[0096] -(D) Flexible resin- The resin composition layer may contain (D) flexible resin as component (D). The (D) flexible resin as this component (D) does not include those corresponding to the above-mentioned components (A) to (C). By incorporating the (D) flexible resin into the resin composition layer, it becomes possible to obtain a cured product excellent in film flexibility. Component (D) may 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 polyimide resin.

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

[0099] Examples of polyolefin resins include ethylene-based copolymer resins such as low-density polyethylene, ultra-low density polyethylene, high-density polyethylene, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, ethylene-methyl acrylate copolymer, etc.; polyolefin polymers such as polypropylene, ethylene-propylene block copolymer, etc.

[0100] Examples of polybutadiene resins include, for example, resins containing a hydrogenated polybutadiene skeleton, hydroxy group-containing polybutadiene resins, phenolic hydroxyl group-containing polybutadiene resins, carboxy group-containing polybutadiene resins, acid anhydride group-containing polybutadiene resins, epoxy group-containing polybutadiene resins, isocyanate group-containing polybutadiene resins, urethane group-containing polybutadiene resins, polyphenylene ether-polybutadiene resins, etc.

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

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

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

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

[0105] Examples of the polycarbonate resin include a hydroxy group-containing carbonate resin, a phenolic hydroxyl group-containing carbonate resin, a carboxy group-containing carbonate resin, an acid anhydride group-containing carbonate resin, an isocyanate group-containing carbonate resin, a urethane group-containing carbonate resin, and the like. Specific examples of the polycarbonate resin include "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., and the like. Specific examples of the polyetheretherketone resin include "Sumipro EK" manufactured by Sumitomo Chemical Company, and the like.

[0106] Examples of the polyester resin include a polyethylene terephthalate resin, a polyethylene naphthalate resin, a polybutylene terephthalate resin, a polybutylene naphthalate resin, a polytrimethylene terephthalate resin, a polytrimethylene naphthalate resin, a polycyclohexanedimethylene terephthalate resin, and the like.

[0107] As the polyimide resin as 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, it preferably has an ester bond. The polyimide resin generally includes those obtained by an imidization reaction of a diamine compound and an acid anhydride.

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

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

[0110] The dimer acid type diamine means a diamine compound obtained by substituting two terminal carboxylic acid groups (-COOH) of dimer acid with an aminomethyl group (-CH2-NH2) or an amino group (-NH2). Dimer acid is a known compound obtained by dimerizing unsaturated fatty acids (preferably those having 11 to 22 carbon atoms, particularly preferably those having 18 carbon atoms), and its industrial manufacturing process is almost standardized in the industry. Dimer acid is mainly composed of dimer acid having 36 carbon atoms obtained by dimerizing unsaturated fatty acids having 18 carbon atoms such as oleic acid and linoleic acid, which are particularly inexpensive and easily available, and is easily available. In addition, dimer acid may contain an arbitrary amount of monomer acid, trimer acid, and other polymerized fatty acids depending on the manufacturing method, degree of purification, etc. Further, although double bonds remain after the polymerization reaction of unsaturated fatty acids, in this specification, hydrogenated products obtained by further hydrogenation reaction to reduce the degree of unsaturation are also included in dimer acid. Commercially available dimer acid type diamines are available, for example, "PRIAMINE1073", "PRIAMINE1074", "PRIAMINE1075" manufactured by Croda Japan; "Versamine 551", "Versamine 552" manufactured by Cognis Japan, etc.

[0111] Examples of the aromatic diamine compound include, for example, a phenylenediamine compound, a naphthalenediamine compound, a dianiline compound, etc., and a dianiline compound is preferred.

[0112] The phenylenediamine compound means a compound composed of a benzene ring having two amino groups, and further, the benzene ring herein may optionally have 1 to 3 substituents. Specific examples of the phenylenediamine compound include 1,4-phenylenediamine, 1,2-phenylenediamine, 1,3-phenylenediamine, 2,4-diaminotoluene, 2,6-diaminotoluene, 3,5-diaminobiphenyl, 2,4,5,6-tetrafluoro-1,3-phenylenediamine, etc.

[0113] The substituent is not particularly limited, and examples thereof include a halogen atom, -OH, -O-C 1-6 alkyl group, -N(C 1-10 alkyl group)2, C 1-20 alkyl group, C 2-30 alkenyl group, C 2-30 alkynyl group, C 6-10 aryl group, -NH2, -CN, -C(O)O-C 1-10 alkyl group, -COOH, -C(O)H, -NO2, etc. Here, the term "C p-q "(p and q are positive integers and satisfy p < q.) represents that the number of carbon atoms of the organic group described immediately after this term is p to q. For example, the expression "C 1-10 alkyl group" indicates an alkyl group having 1 to 10 carbon atoms. These substituents may be bonded to each other to form a ring, and the ring structure includes a spiro ring and a condensed ring.

[0114] The naphthalenediamine compound means a compound composed of a naphthalene ring having two amino groups, and further, the naphthalene ring herein may optionally have 1 to 3 substituents. The substituents are the same as those that the phenylenediamine compound may have. Specific examples of the naphthalenediamine compound include 1,5-diaminonaphthalene, 1,8-diaminonaphthalene, 2,6-diaminonaphthalene, 2,3-diaminonaphthalene, and the like.

[0115] The dianiline compound means a compound containing two aniline structures in the molecule, and further, the two benzene rings in the two aniline structures may each optionally have 1 to 3 substituents. The substituents are the same as those that the phenylenediamine compound may have. The two aniline structures in the dianiline compound may be bonded directly and / or via one or two linker structures having 1 to 100 skeletal atoms selected from carbon atoms, oxygen atoms, sulfur atoms, and nitrogen atoms. The dianiline compound includes those in which the two aniline structures are bonded by two bonds.

[0116] As the "linker structure" in the dianiline compound, specifically, -NHCO-, -CONH-, -OCO-, -COO-, -CH2-, -CH2CH2-, -CH2CH2CH2-, -CH2CH2CH2CH2-, -CH2CH2CH2CH2CH2-, -CH(CH3)-, -C(CH3)2-, -C(CF3)2-, -CH=CH-, -O-, -S-, -CO-, -SO2-, -NH-, -Ph-, -Ph-Ph-, -C(CH3)2-Ph-C(CH3)2-, -O-Ph-O-, -O-Ph-Ph-O-, -O-Ph-SO2-Ph-O-, -O-Ph-C(CH3)2-Ph-O-, -Ph-CO-O-Ph-, -C(CH3)2-Ph-C(CH3)2-, -O-Ph-C(CH3)2-Ph-C(CH3)2-Ph-O-, -Ph-O-Ph-C(CH3)2-Ph-C(CH3)2-Ph-O-Ph-, the groups represented by the following formulas (I) and (II), and groups composed of combinations thereof, etc. may be mentioned. In this specification, "Ph" represents a 1,4-phenylene group, a 1,3-phenylene group or a 1,2-phenylene group. Among them, as the linker structure, -COO-, -Ph-CO-O-Ph-, -C(CH3)2-Ph-C(CH3)2-, -O-Ph-C(CH3)2-Ph-C(CH3)2-Ph-O-, or -Ph-O-Ph-C(CH3)2-Ph-C(CH3)2-Ph-O-Ph- is preferable.

[0117]

Chemical formula

[0118] In one embodiment, as the diamine compound, a diamine compound represented by the following formula (D-1) is preferable.

Chemical formula

[0119] The alkyl group represented by R 9 and R 9’ in formula (D-1) refers to a linear, branched or cyclic monovalent aliphatic saturated hydrocarbon group. As the alkyl group, an alkyl group having 1 to 6 carbon atoms is preferable, and an alkyl group having 1 to 3 carbon atoms is more preferable. Examples of such an alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a pentyl group, an isopentyl group, a neopentyl group, a cyclopentyl group, a cyclohexyl group and the like.

[0120] R 9 and R 9’The alkenyl group represented by [it] refers to a linear, branched or cyclic monovalent unsaturated hydrocarbon group having at least one carbon-carbon double bond. As the alkenyl group, an alkenyl group having 2 to 6 carbon atoms is preferable, and an alkenyl group having 2 or 3 carbon atoms is more preferable. Examples of such alkenyl groups include a vinyl group, a 1-propenyl group, a 2-propenyl group, a 2-methyl-1-propenyl group, a 1-butenyl group, a 2-butenyl group, a 3-butenyl group, a 3-methyl-2-butenyl group, a 1-pentenyl group, a 2-pentenyl group, a 3-pentenyl group, a 4-pentenyl group, a 4-methyl-3-pentenyl group, a 1-hexenyl group, a 3-hexenyl group, a 5-hexenyl group, a 2-cyclohexenyl group, and the like. The substituent of the alkenyl group in the "substituted or unsubstituted alkenyl group" is not particularly limited, and examples thereof include a halogen atom, a cyano group, an alkoxy group, an aryl group, a heteroaryl group, an amino group, a nitro group, a hydroxy group, a carboxy group, a sulfo group, and the like. The number of substituents is preferably 1 to 3, and more preferably 1.

[0121] The substituent of the alkyl group in the "substituted or unsubstituted alkyl group" and the substituent of the alkenyl group in the "substituted or unsubstituted alkenyl group" are not particularly limited, and examples thereof include a halogen atom, a cyano group, an alkoxy group, an amino group, a nitro group, a hydroxy group, a carboxy group, a sulfo group, and the like. The number of substituents is preferably 1 to 3, and more preferably 1.

[0122] The alkoxy group refers to a monovalent group (alkyl-O-) formed by bonding an alkyl group to an oxygen atom. As the alkoxy group, an alkoxy group having 1 to 6 carbon atoms is preferable, and an alkoxy group having 1 to 3 carbon atoms is more preferable. Examples of such alkoxy groups include a methoxy group, an ethoxy group, a propoxy group, an isopropoxy group, a butoxy group, an isobutoxy group, a sec-butoxy group, a tert-butoxy group, a pentyloxy group, and the like.

[0123] X in formula (D-1) 10The alkylene group represented by [it] refers to a linear, branched or cyclic divalent aliphatic saturated hydrocarbon group, preferably an alkylene group having 1 to 6 carbon atoms, more preferably an alkylene group having 1 to 3 carbon atoms. Examples of the alkylene group include, for example, -CH2-, -CH2-CH2-, -CH(CH3)-, -CH2-CH2-CH2-, -CH2-CH(CH3)-, -CH(CH3)-CH2-, -C(CH3)2-, -CH2-CH2-CH2-CH2-, -CH2-CH2-CH(CH3)-, -CH2-CH(CH3)-CH2-, -CH(CH3)-CH2-CH2-, -CH2-C(CH3)2-, -C(CH3)2-CH2- and the like. The substituent of the alkylene group in the "substituted or unsubstituted alkylene group" is not particularly limited, and examples thereof include a halogen atom, a cyano group, an alkoxy group, an aryl group, a heteroaryl group, an amino group, a nitro group, a hydroxy group, a carboxy group, a sulfo group and the like. The number of substituents is preferably 1 to 3, more preferably 1.

[0124] R in formula (D-1) 10 The aryl group represented by [it] is preferably an aryl group having 6 to 14 carbon atoms, more preferably an aryl group having 6 to 10 carbon atoms. Examples of such an aryl group include, for example, a phenyl group, a 1-naphthyl group, a 2-naphthyl group and the like, and preferably a phenyl group. The substituent of the aryl group in the "substituted or unsubstituted aryl group" is not particularly limited, and examples thereof include a halogen atom, a cyano group, an alkyl group, an alkoxy group, an aryl group, a heteroaryl group, an amino group, a nitro group, a hydroxy group, a carboxy group, a sulfo group and the like. The number of substituents is preferably 1 to 3, more preferably 1.

[0125] R in formula (D-1) 10The heteroaryl group represented by means an aromatic heterocyclic group having 1 to 4 heteroatoms selected from an oxygen atom, a nitrogen atom and a sulfur atom. The heteroaryl group is preferably a monocyclic, bicyclic or tricyclic (preferably monocyclic) aromatic heterocyclic group having 5 to 12 members (preferably 5 or 6 members). Examples of such a heteroaryl group include a furyl group, a thienyl group, a pyrrolyl group, an oxazolyl group, an isoxazolyl group, a thiazolyl group, an isothiazolyl group, an imidazolyl group, a pyrazolyl group, a 1,2,3-oxadiazolyl group, a 1,2,4-oxadiazolyl group, a 1,3,4-oxadiazolyl group, a furazanyl group, a 1,2,3-thiadiazolyl group, a 1,2,4-thiadiazolyl group, a 1,3,4-thiadiazolyl group, a 1,2,3-triazolyl group, a 1,2,4-triazolyl group, a tetrazolyl group, a pyridyl group, a pyridazinyl group, a pyrimidinyl group, a pyrazinyl group, a triazinyl group and the like. The substituents of the heteroaryl group in the "substituted or unsubstituted heteroaryl group" are the same as the substituents of the aryl group in the "substituted or unsubstituted aryl group".

[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 are preferably each independently a hydrogen atom or -X 10 -R 10 .

[0127] R 1 ~R 8 at least one of is -X 10 -R 10 Preferably, one or two of R 1 ~R 8 are -X 10 -R 10 More preferably, one or two of R 5 ~R 8 are -X 10 -R 10and more preferably, R 5 and R 7 one or two of which are -X 10 -R 10 .

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

[0129] X 9 each independently represents a single bond, -NR 9’ -, -O-, -S-, -CO-, -SO2-, -NR 9’ CO-, -CONR 9’ -, -OCO-, or -COO-. R 9 each independently represents a substituted or unsubstituted alkyl group, or a substituted or unsubstituted alkenyl group. X 9 is preferably a single bond.

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

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

[0133] In one embodiment, the diamine compound represented by formula (D-1) is preferably a compound represented by the following formula (D-2), and more preferably a 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

Chemical formula

[0134] In another embodiment, the diamine compound is specifically 4,4'-diamino-2,2'-ditrifluoromethyl-1,1'-biphenyl, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl sulfide, 4-aminophenyl 4-aminobenzoate, 1,3-bis(3-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, 1,4-bis(4-aminophenoxy)benzene, 2,2-bis(4-aminophenyl)propane, 4,4'-(hexafluoroisopropylidene)dianiline, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane, α,α-bis[4-(4-aminophenoxy)phenyl]-1,3-diisopropylbenzene, α,α-bis[4-(4-aminophenoxy)phenyl]-1,4-diisopropylbenzene, 4,4'-(9-fluorenylidene)dianiline, 2,2-bis(3-methyl-4-aminophenyl)propane, 2,2-bis(3-methyl-4-aminophenyl)benzene, 4,4'-diamino-3,3'-dimethyl-1,1'-biphenyl, 4,4'-diamino-2,2'-dimethyl-1,1'-biphenyl, 9,9'-bis(3-methyl-4-aminophenyl)fluorene, 5-(4-aminophenoxy)-3-[4-(4-aminophenoxy)phenyl]-1,1,3-trimethylindane, 4,4'-(m-phenylenediisopropylidene)dianiline (Bisaniline-M), 4,4'-[1,4-phenylenebis[(1-methylethylidene)-4,1-phenyleneoxy]]bisbenzeneamine (BPPAN), etc. Preferably, they are 4,4'-(m-phenylenediisopropylidene)dianiline and 4,4'-[1,4-phenylenebis[(1-methylethylidene)-4,1-phenyleneoxy]]bisbenzeneamine.Note that 4,4'-(m-phenylenediisopropylidene)dianiline (Bisaniline-M) is a compound represented by the following formula (I), and 4,4'-[1,4-phenylenebis[(1-methylethylidene)-4,1-phenyleneoxy]]bisbenzenamine (BPPAN) is a compound represented by the following formula (II). [Chemical formula]

[0135] In one embodiment, the diamine compound for preparing the polyimide resin preferably contains 4,4'-(m-phenylenediisopropylidene)dianiline (the compound represented by the above formula (I)), more preferably contains a combination of 4,4'-(m-phenylenediisopropylidene)dianiline and a diamine compound represented by formula (D-1), even more preferably contains a combination of 4,4'-(m-phenylenediisopropylidene)dianiline and a diamine compound represented by formula (D-2), and even more preferably contains a combination of (5-amino-2-biphenyl)-4-aminobenzoate (the compound represented by the above formula (D-3)).

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

[0137] As for the diamine compound, commercially available ones may be used, or those synthesized by known methods may also be used. For example, the diamine compound represented by the formula (D-1) can be synthesized by the synthesis method described in Patent No. 6240798 or a method analogous thereto. The diamine compound may be used alone or in combination of two or more.

[0138] The acid anhydride for preparing the polyimide resin is not particularly limited, but in a preferred embodiment, it is an aromatic tetracarboxylic dianhydride. Examples of the aromatic tetracarboxylic dianhydride include benzene tetracarboxylic dianhydride, naphthalene tetracarboxylic dianhydride, anthracene tetracarboxylic dianhydride, diphthalic dianhydride, etc., and preferably diphthalic dianhydride.

[0139] Benzene tetracarboxylic dianhydride means the dianhydride of benzene having four carboxy groups, and further, the benzene ring herein may optionally have 1 to 3 substituents. Here, examples of the substituent include a halogen atom, a cyano group, and -X 13 -R 13 (the same as the definition of the following formula (D-4)) are preferred. Specific examples of the benzene tetracarboxylic dianhydride include pyromellitic dianhydride, 1,2,3,4-benzene tetracarboxylic dianhydride, etc.

[0140] Naphthalene tetracarboxylic dianhydride means the dianhydride of naphthalene having four carboxy groups, and further, the naphthalene ring herein may optionally have 1 to 3 substituents. Here, examples of the substituent include a halogen atom, a cyano group, and -X 13 -R 13 (the same as the definition of the following formula (D-4)) are preferred. Specific examples of the naphthalene tetracarboxylic dianhydride include 1,4,5,8-naphthalene tetracarboxylic dianhydride, 2,3,6,7-naphthalene tetracarboxylic dianhydride, etc.

[0141] Anthracenetetracarboxylic dianhydride means a dianhydride of anthracene having four carboxy groups, and further, the anthracene ring herein may optionally have 1 to 3 substituents. Here, examples of the substituent include a halogen atom, a cyano group, and -X 13 -R 13 (the same as the definition of the following formula (D-4)) are preferred. Specific examples of the anthracenetetracarboxylic dianhydride include 2,3,6,7-anthracenetetracarboxylic dianhydride and the like.

[0142] Phthalic dianhydride means a compound containing two phthalic anhydrides in the molecule, and further, the two benzene rings in the two phthalic anhydrides may each optionally have 1 to 3 substituents. Here, examples of the substituent include a halogen atom, a cyano group, and -X 13 -R 13 (the same as the definition of the following formula (D-4)) are preferred. The two phthalic anhydrides in the phthalic dianhydride may be bonded directly or via a linker structure having 1 to 100 backbone atoms selected from a carbon atom, an oxygen atom, a sulfur atom, and a nitrogen atom.

[0143] Examples of the phthalic dianhydride include the compound represented by the formula (D-4). [Chemical formula] (In the formula, R 11 and R 12 each independently represent a halogen atom, a cyano group, a nitro group, or -X 13 -R 13 and X 13 each independently represent a single bond, -NR 13’ -, -O-, -S-, -CO-, -SO2-, -NR 13’ CO-, -CONR 13’ -, -OCO-, or -COO-, and R 13 each independently represent a substituted or unsubstituted alkyl group, or a substituted or unsubstituted alkenyl group, R13’ each independently represents a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted alkenyl group, Y represents a single bond or a linker structure having 1 to 100 backbone atoms selected from carbon atoms, oxygen atoms, sulfur atoms, and nitrogen atoms, n1 and m1 each independently represent an integer from 0 to 3. )

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

[0145] The "linker structure" in Y has 1 to 100 backbone atoms selected from carbon atoms, oxygen atoms, sulfur atoms, and nitrogen atoms. The "linker structure" is preferably -[A-Ph] a -A-[Ph-A] b - [wherein A each independently represents a single bond, -(substituted or unsubstituted alkylene group)-, -O-, -S-, -CO-, -SO2-, -CONH-, -NHCO-, -COO-, or -OCO-, and a and b each independently represent an integer from 0 to 2 (preferably 0 or 1). ] is a divalent group represented by

[0146] Specific examples of the "linker structure" in Y include -CH2-, -CH2CH2-, -CH2CH2CH2-, -CH2CH2CH2CH2-, -CH2CH2CH2CH2CH2-, -CH(CH3)-, -C(CH3)2-, -O-, -CO-, -SO2-, -Ph-, -O-Ph-O-, -O-Ph-SO2-Ph-O-, -O-Ph-C(CH3)2-Ph-O-, etc., and -O-Ph-C(CH3)2-Ph-O- is preferred.

[0147] Specific examples of the diphthalic anhydride include 3,3',4,4'-benzophenone tetracarboxylic dianhydride, 3,3',4,4'-diphenyl ether tetracarboxylic dianhydride, 3,3',4,4'-diphenyl sulfone tetracarboxylic dianhydride, 3,3',4,4'-biphenyl tetracarboxylic dianhydride, 2,2',3,3'-biphenyl tetracarboxylic dianhydride, 2,3,3',4'-biphenyl tetracarboxylic dianhydride, 2,3,3',4'-benzophenone tetracarboxylic dianhydride, 2,3,3',4'-diphenyl ether tetracarboxylic dianhydride, 2,3,3',4'-diphenyl sulfone tetracarboxylic dianhydride, 2,2'-bis(3,4-dicarboxyphenoxyphenyl) sulfone dianhydride, methylene-4,4'-diphthalic dianhydride, 1,1-ethynylidene-4,4'-diphthalic dianhydride, 2,2-propylidene-4,4'-diphthalic dianhydride, 1,2-ethylene-4,4'-diphthalic dianhydride, 1,3-trimethylene-4,4'-diphthalic dianhydride, 1,4-tetramethylene-4,4'-diphthalic dianhydride, 1,5-pentamethylene-4,4'-diphthalic dianhydride, 1,3-bis(3,4-dicarboxyphenyl) benzene dianhydride, 1,4-bis(3,4-dicarboxyphenyl) benzene dianhydride, 1,3-bis(3,4-dicarboxyphenoxy) benzene dianhydride, 1,4-bis(3,4-dicarboxyphenoxy) benzene dianhydride, 2,2-bis(2,3-dicarboxyphenyl) propane dianhydride, 2,2-bis(3,4-dicarboxyphenyl) propane dianhydride, 4,4'-(4,4'-isopropylidenediphenoxy) bisphthalic dianhydride (BPADA), and the like.

[0148] In one embodiment, the diphthalic acid compound represented by the formula (D-4) is preferably a compound represented by the following formula (D-5), and more preferably a compound represented by the following formula (D-6) (4,4'-(4,4'-isopropylidenediphenoxy) bisphthalic dianhydride: BPADA). [Chemical formula] (In the formula, R 11 and R12 each independently represents a halogen atom, a cyano group, a nitro group, or -X 13 -R 13 wherein n1 and m1 each independently represent an integer of 0 to 3, and other symbols are the same as in formula (D-4).) [Chemical formula]

[0149] Commercially available aromatic tetracarboxylic dianhydrides may be used, or those synthesized by known methods or methods analogous thereto may be used. The aromatic tetracarboxylic dianhydride may be used alone or in combination of two or more.

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

[0151] Specific examples of the other acid anhydrides include aliphatic tetracarboxylic dianhydrides such as 1,2,3,4-cyclobutanetetracarboxylic dianhydride, cyclopentanetetracarboxylic dianhydride, cyclohexane-1,2,3,4-tetracarboxylic dianhydride, cyclohexane-1,2,4,5-tetracarboxylic dianhydride, 3,3’,4,4’-bicyclohexyltetracarboxylic dianhydride, carbonyl-4,4’-bis(cyclohexane-1,2-dicarboxylic acid) dianhydride, methylene-4,4’-bis(cyclohexane-1,2-dicarboxylic acid) dianhydride, 1,2-ethylene-4,4’-bis(cyclohexane-1,2-dicarboxylic acid) dianhydride, oxy-4,4’-bis(cyclohexane-1,2-dicarboxylic acid) dianhydride, thio-4,4’-bis(cyclohexane-1,2-dicarboxylic acid) dianhydride, sulfonyl-4,4’-bis(cyclohexane-1,2-dicarboxylic acid) dianhydride, etc.

[0152] The content of the structure derived from the aromatic tetracarboxylic dianhydride in the entire structure derived from the acid anhydride constituting the polyimide resin is preferably 10 mol% or more, more preferably 30 mol% or more, still more preferably 50 mol% or more, yet more preferably 70 mol% or more, even 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

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

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

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

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

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

[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-phenylenediisopropylidene)dianiline (the compound represented by the above formula (I)) with 4,4'-(4,4'-isopropylidenediphenoxy)bisphtalic dianhydride (BPADA: the compound represented by the above formula (D-6)). Further, in such an embodiment, the polyimide resin more preferably contains, in addition to the structural unit D1, 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'-isopropylidenediphenoxy)bisphtalic dianhydride

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

[0161] As solvents used for preparing the polyimide resin as component (D), there may be mentioned amide solvents such as N,N-dimethylacetamide, N,N-diethylacetamide, N,N-dimethylformamide, N-methyl-2-pyrrolidone; ketone solvents such as acetone, methyl ethyl ketone (MEK) and cyclohexanone; ester solvents such as γ-butyrolactone; and hydrocarbon solvents such as cyclohexane and methylcyclohexane. Further, for preparing the polyimide resin, an imidization catalyst, an azeotropic dehydrating solvent, an acid catalyst, etc. may be used as necessary. Examples of the imidization catalyst include tertiary amines such as triethylamine, triisopropylamine, triethylenediamine, N-methylpyrrolidine, N-ethylpyrrolidine, N,N-dimethyl-4-aminopyridine, and pyridine. Examples of the azeotropic dehydrating solvent include toluene, xylene, ethylcyclohexane, etc. Examples of the acid catalyst include acetic anhydride, etc. The amounts of use of the imidization catalyst, the azeotropic dehydrating solvent, the acid catalyst, etc. can be appropriately set by those skilled in the art. The reaction temperature for preparing the polyimide resin is usually 100 to 250°C.

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

[0163] As the content of component (D), when the non-volatile component in the resin composition layer is 100% by mass, it is preferably 0.1% by mass or more, more preferably 0.15% by mass or more, still more preferably 0.2% by mass or more, 0.3% by mass or more, 0.4% by mass or more, 0.5% by mass or more, and preferably 30% by mass or less, more preferably 20% by mass or less, still more preferably 10% by mass or less, 8% by mass or less, 5% by mass or less, 4% by mass or less, 3% by mass or less, 3% by mass or less, 2% by mass or less, 1.5% by mass or less.

[0164] When the content of the (D) component is based on 100% by mass of the resin component in the resin composition layer, it is preferably 0.5% by mass or more, more preferably 1% by mass or more, still more preferably 1.5% by mass or more, and preferably 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 (A-1) component contained in the resin composition layer is a1 and the content of the (D) component contained in the resin composition layer is d1, a1 / d1 is preferably 0.1 or more, more preferably 1 or more, still more preferably 5 or more, 7 or more, and preferably 25 or less, more preferably 20 or less, still more preferably 15 or less, 10 or less. By adjusting the contents of the (A-1) component and the (D) component so that a1 / d1 is within such a range, the effects of the present invention can be remarkably obtained.

[0166] When the total content of the (B) component and the (D) component is based on 100% by mass of the non-volatile components in the resin composition layer, it is preferably 10% by mass or more, more preferably 15% by mass or more, still more preferably 20% by mass or more, and preferably 65% by mass or less, more preferably 50% by mass or less, still more preferably 45% by mass or less, 40% by mass or less.

[0167] -(E) Phenoxy resin- The resin composition layer may contain a (E) phenoxy resin as the (E) component. The (E) phenoxy resin as the (E) component does not include those corresponding to the above-mentioned (A) to (D) components. By containing the (E) phenoxy resin in the resin composition layer, the stress during curing of the resin composition layer can be relaxed, and the film flexibility can also be improved. The (E) component may be used alone or in combination of two or more.

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

[0169] Examples of the (E) phenoxy resin include phenoxy resins having one or more skeletons selected from the group consisting of a bisphenol A skeleton, a bisphenol F skeleton, a bisphenol S skeleton, a bisphenol acetophenone skeleton, a novolak skeleton, a biphenyl skeleton, a fluorene skeleton, a dicyclopentadiene skeleton, a norbornene skeleton, a naphthalene skeleton, an anthracene skeleton, an adamantane skeleton, a terpene skeleton, and a trimethylcyclohexane skeleton. The terminal of the (B) phenoxy resin may be any functional group such as a phenolic hydroxyl group or an epoxy group.

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

[0171] When the content of component (E) is based on 100% by mass of the non-volatile components in the resin composition layer, it is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, still more preferably 1% by mass or more, and preferably 10% by mass or less, more preferably 5% by mass or less, still more preferably 3% by mass or less, and it is particularly preferable that it is not contained.

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

[0173] -(F) Flame retardant- The resin composition layer may contain a (F) flame retardant as component (F). The (F) flame retardant as this component (F) does not include those corresponding to the above-mentioned components (A) to (E). By containing the (F) flame retardant, the (F) flame retardant can react with the epoxy resin in component (D), and it becomes possible to further improve the glass transition temperature and flame retardancy of the cured product. Component (F) may be used alone or in combination of two or more.

[0174] Examples of the (F) flame retardant include phosphazene compounds, organic phosphorus-based flame retardants, organic nitrogen-containing phosphorus compounds, nitrogen compounds, silicone-based flame retardants, metal hydroxides, etc., and phosphazene compounds are preferred. The flame retardant may be used alone or in combination of two or more.

[0175] The phosphazene compound is not particularly limited as long as it is a cyclic compound containing nitrogen and phosphorus as constituent elements, but the phosphazene compound is preferably a phosphazene compound having a phenolic hydroxyl group.

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

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

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

[0180] -(G) Curing accelerator- The resin composition layer may contain a (G) curing accelerator as the (G) component. The (G) curing accelerator as the (G) component does not include those corresponding to the above-mentioned (A) to (F) components. The (G) curing accelerator has a function as a curing catalyst that promotes the curing of the epoxy resin in the (D) component.

[0181] (G) As a curing accelerator, a compound that accelerates the curing of the epoxy resin can be used. Examples of such (G) curing accelerators include phosphorus-based curing accelerators, urea-based curing accelerators, guanidine-based curing accelerators, imidazole-based curing accelerators, metal-based curing accelerators, amine-based curing accelerators, and the like. The (G) curing accelerator may be used alone or in combination of two or more.

[0182] Examples of phosphorus-based curing accelerators include aliphatic phosphonium salts such as tetrabutylphosphonium bromide, tetrabutylphosphonium chloride, tetrabutylphosphonium acetate, tetrabutylphosphonium decanoate, tetrabutylphosphonium laurate, bis(tetrabutylphosphonium) pyromellitate, tetrabutylphosphonium hydrogen hexahydrophthalate, tetrabutylphosphonium 2,6-bis[(2-hydroxy-5-methylphenyl)methyl]-4-methylphenolate, di-tert-butyldimethylphosphonium tetraphenylborate; aromatic phosphonium salts such as methyltriphenylphosphonium bromide, ethyltriphenylphosphonium bromide, propyltriphenylphosphonium bromide, butyltriphenylphosphonium bromide, benzyltriphenylphosphonium chloride, tetraphenylphosphonium bromide, p-tolyltriphenylphosphonium tetra-p-tolylborate, tetraphenylphosphonium tetraphenylborate, tetraphenylphosphonium tetra-p-tolylborate, triphenylethylphosphonium tetraphenylborate, tris(3-methylphenyl)ethylphosphonium tetraphenylborate, tris(2-methoxyphenyl)ethylphosphonium tetraphenylborate, (4-methylphenyl)triphenylphosphonium thiocyanate, tetraphenylphosphonium thiocyanate, butyltriphenylphosphonium thiocyanate; aromatic phosphine-borane complexes such as triphenylphosphine·triphenylborane; aromatic phosphine-quinone addition reactants such as triphenylphosphine·p-benzoquinone addition reactant; aliphatic phosphines such as tributylphosphine, tri-tert-butylphosphine, trioctylphosphine, di-tert-butyl(2-butenyl)phosphine, di-tert-butyl(3-methyl-2-butenyl)phosphine, tricyclohexylphosphine;Aromatic phosphines such as dibutylphenylphosphine, di-tert-butylphenylphosphine, methyldiphenylphosphine, ethyldiphenylphosphine, butyldiphenylphosphine, diphenylcyclohexylphosphine, triphenylphosphine, tri-o-tolylphosphine, tri-m-tolylphosphine, tri-p-tolylphosphine, tris(4-ethylphenyl)phosphine, tris(4-propylphenyl)phosphine, tris(4-isopropylphenyl)phosphine, tris(4-butylphenyl)phosphine, tris(4-tert-butylphenyl)phosphine, tris(2,4-dimethylphenyl)phosphine, tris(2,5-dimethylphenyl)phosphine, tris(2,6-dimethylphenyl)phosphine, tris(3,5-dimethylphenyl)phosphine, tris(2,4,6-trimethylphenyl)phosphine, tris(2,6-dimethyl-4-ethoxyphenyl)phosphine, tris(2-methoxyphenyl)phosphine, tris(4-methoxyphenyl)phosphine, tris(4-ethoxyphenyl)phosphine, tris(4-tert-butoxyphenyl)phosphine, diphenyl-2-pyridylphosphine, 1,2-bis(diphenylphosphino)ethane, 1,3-bis(diphenylphosphino)propane, 1,4-bis(diphenylphosphino)butane, 1,2-bis(diphenylphosphino)acetylene, 2,2'-bis(diphenylphosphino)diphenylether, etc. are mentioned.;

[0183] Examples of urea-based curing accelerators include, for example, 1,1-dimethylurea; aliphatic dimethylureas such as 1,1,3-trimethylurea, 3-ethyl-1,1-dimethylurea, 3-cyclohexyl-1,1-dimethylurea, 3-cyclooctyl-1,1-dimethylurea; aromatic dimethylureas such as 3-phenyl-1,1-dimethylurea, 3-(4-chlorophenyl)-1,1-dimethylurea, 3-(3,4-dichlorophenyl)-1,1-dimethylurea, 3-(3-chloro-4-methylphenyl)-1,1-dimethylurea, 3-(2-methylphenyl)-1,1-dimethylurea, 3-(4-methylphenyl)-1,1-dimethylurea, 3-(3,4-dimethylphenyl)-1,1-dimethylurea, 3-(4-isopropylphenyl)-1,1-dimethylurea, 3-(4-methoxyphenyl)-1,1-dimethylurea, 3-(4-nitrophenyl)-1,1-dimethylurea, 3-[4-(4-methoxyphenoxy)phenyl]-1,1-dimethylurea, 3-[4-(4-chlorophenoxy)phenyl]-1,1-dimethylurea, 3-[3-(trifluoromethyl)phenyl]-1,1-dimethylurea, N,N-(1,4-phenylene)bis(N’,N’-dimethylurea), N,N-(4-methyl-1,3-phenylene)bis(N’,N’-dimethylurea) [toluene bisdimethylurea], and the like.

[0184] Examples of guanidine-based curing accelerators include, for example, dicyandiamide, 1-methylguanidine, 1-ethylguanidine, 1-cyclohexylguanidine, 1-phenylguanidine, 1-(o-tolyl)guanidine, dimethylguanidine, diphenylguanidine, trimethylguanidine, tetramethylguanidine, pentamethylguanidine, 1,5,7-triazabicyclo[4.4.0]dec-5-ene, 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene, 1-methylbiguanide, 1-ethylbiguanide, 1-n-butylbiguanide, 1-n-octadecylbiguanide, 1,1-dimethylbiguanide, 1,1-diethylbiguanide, 1-cyclohexylbiguanide, 1-allylbiguanide, 1-phenylbiguanide, 1-(o-tolyl)biguanide, and the like.

[0185] Examples of imidazole-based curing accelerators include imidazole compounds such as 2-methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 1,2-dimethylimidazole, 2-ethyl-4-methylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 1-benzyl-2-methylimidazole, 1-benzyl-2-phenylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-undecylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 1-cyanoethyl-2-phenylimidazole, 1-cyanoethyl-2-undecylimidazolium trimellitate, 1-cyanoethyl-2-phenylimidazolium trimellitate, 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-undecylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-ethyl-4'-methylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine isocyanuric acid adduct, 2-phenylimidazole isocyanuric acid adduct, 2-phenyl-4,5-dihydroxymethylimidazole, 2-phenyl-4-methyl-5-hydroxymethylimidazole, 2,3-dihydro-1H-pyrrolo[1,2-a]benzimidazole, 1-dodecyl-2-methyl-3-benzylimidazolium chloride, 2-methylimidazoline, 2-phenylimidazoline, and adducts of imidazole compounds and epoxy resins. Commercially available products of imidazole-based curing accelerators include, for example, "1B2PZ", "2E4MZ", "2MZA-PW", "2MZ-OK", "2MA-OK", "2MA-OK-PW", "2PHZ", "2PHZ-PW", "Cl1Z", "Cl1Z-CN", "Cl1Z-CNS", "C11Z-A" manufactured by Shikoku Kasei Kogyo Co., Ltd.; "P200-H50" manufactured by Mitsubishi Chemical Corporation, etc.

[0186] Examples of the metal-based hardening accelerators include organometallic complexes or organometallic salts of metals such as cobalt, copper, zinc, iron, nickel, manganese, tin, etc. Specific examples of the organometallic complexes include organocobalt complexes such as cobalt(II) acetylacetonate and cobalt(III) acetylacetonate, organocopper complexes such as copper(II) acetylacetonate, organozinc complexes such as zinc(II) acetylacetonate, organoiron complexes such as iron(III) acetylacetonate, organonickel complexes such as nickel(II) acetylacetonate, and organomanganese complexes such as manganese(II) acetylacetonate. Examples of the organometallic salts include zinc octylate, tin octylate, zinc naphthenate, cobalt naphthenate, tin stearate, zinc stearate, etc.

[0187] Examples of the amine-based hardening accelerators include trialkylamines such as triethylamine and tributylamine, 4-dimethylaminopyridine, benzyldimethylamine, 2,4,6-tris(dimethylaminomethyl)phenol, 1,8-diazabicyclo(5,4,0)-undecene, etc. As the amine-based hardening accelerator, commercially available products may be used, for example, "MY-25" manufactured by Ajinomoto Fine-Techno Co., Inc., etc.

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

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

[0190] -(H) Other Additives- The resin composition layer may contain, as an optional non-volatile component, (H) other additives. Examples of (H) other additives include, for example, elastomers (excluding those corresponding to component (D) and component (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 and montmorillonite; antifoaming agents such as silicone-based antifoaming agents, acrylic-based antifoaming agents, fluorine-based antifoaming agents, and vinyl resin-based antifoaming agents; ultraviolet absorbers such as benzotriazole-based ultraviolet absorbers; adhesion improvers such as urea silane; adhesion imparting agents such as triazole-based adhesion imparting agents, tetrazole-based adhesion imparting agents, and triazine-based adhesion imparting agents; antioxidants such as hindered phenol-based antioxidants; fluorescent brighteners such as stilbene derivatives; surfactants such as fluorine-based surfactants and silicone-based surfactants; dispersants such as phosphate ester-based dispersants, polyoxyalkylene-based dispersants, acetylene-based dispersants, silicone-based dispersants, anionic dispersants, and cationic dispersants; stabilizers such as borate-based stabilizers, titanate-based stabilizers, aluminate-based stabilizers, zirconate-based stabilizers, isocyanate-based stabilizers, carboxylic acid-based stabilizers, and carboxylic anhydride-based stabilizers; photopolymerization initiation aids such as tertiary amines; photosensitizers such as pyralizones, anthracenes, coumarins, xanthones, and thioxanthones. (H) Other additives may be used alone or in combination of two or more.

[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 still more preferably 55 μm or less. The lower limit of the thickness of the resin composition layer is not particularly limited, but may usually 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 and scratches on the surface of the resin composition layer.

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

[0194] When using a film made of a plastic material as the protective film, examples of the plastic material include polyesters such as polyethylene terephthalate (hereinafter sometimes abbreviated as "PET") and polyethylene naphthalate (hereinafter sometimes abbreviated as "PEN"), polycarbonate (hereinafter sometimes abbreviated as "PC"), acrylics such as polymethyl methacrylate (PMMA), cyclic polyolefin, triacetyl cellulose (TAC), polyethersulfide (PES), polyether ketone, polyimide, and the like. Among them, polyethylene terephthalate and polyethylene naphthalate are preferred, and inexpensive polyethylene terephthalate is particularly preferred.

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

[0196] The protective film may be subjected to a mat treatment, a corona treatment, or an antistatic treatment on the surface that joins the resin composition layer.

[0197] Further, as the protective film, a protective film with a release layer having a release layer on the surface that bonds to the resin composition layer may be used. Examples of the release agent used for the release layer of the protective film with a release layer include one or more release agents selected from the group consisting of alkyd resins, polyolefin resins, urethane resins, and silicone resins. As the protective film with a release layer, a commercially available product may be used. For example, "SK-1", "AL-5", "AL-7" manufactured by Lintec Corporation, which are PET films having a release layer mainly composed of an alkyd resin-based release agent, "Lumirror T60", "Lumirror R80", "Lumirror" manufactured by Toray Industries, Inc., "Purex" manufactured by Teijin Limited, "Unipile" manufactured by Unitika Ltd., etc. may be mentioned.

[0198] The thickness of the protective film is not particularly limited, but for example, it is 1 μm to 40 μm. When the protective film has a multilayer structure such as a protective film with a release layer, it is preferable that the thickness of the entire protective film is within such a range.

[0199] <Method for manufacturing a resin sheet with a metal foil> The method for manufacturing a resin sheet with a metal foil is, for example, preparing a resin varnish in which the components contained in the resin composition layer are dissolved in a solvent, applying this resin varnish onto a protective film using a die coater or the like, and further drying it to form a resin composition layer on the protective film. Next, a resin sheet with a metal foil can be manufactured by laminating a metal foil onto the surface of the resin composition layer using a roll laminator or the like. As the solvent, those described above can be used.

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

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

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

[0203] Also, the 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, still more preferably 8%. The lower limit is preferably 0.01% or more, more preferably 0.1 mass% or more, still more preferably 0.5 mass% or more, 1 mass% or more. The weight loss rate can be measured by the method described in the examples below.

[0204] The resin sheet with a metal foil can be wound up and stored in a roll. When using the resin sheet with a metal foil, it can be used by peeling off the protective film.

[0205] <Physical properties of the resin sheet with a metal foil, etc.> Since the resin sheet with a metal foil of the present invention has a resin composition layer containing a specific amount of the component (A-1), it exhibits the characteristic that the glass transition temperature (Tg) of the cured product of the resin composition layer thermally cured by vacuum press treatment is high. The glass transition temperature of the cured product of the resin composition layer thermally cured by vacuum press treatment is preferably 150 °C or higher, more preferably 155 °C or higher, still more 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] In the resin composition layer of the resin sheet with a metal foil of the present invention, since it has a resin composition layer containing a specific amount of component (A-1), it exhibits the characteristic of excellent film flexibility. Therefore, it provides a resin sheet with a metal foil having excellent handleability. Specifically, the resin sheet with a metal foil is cut with a temporary fixing device, and cracks and chips at the cut edge ends are visually confirmed. As a result, there are no cracks or chips in the resin sheet with a metal foil. The evaluation of film flexibility can be measured by the method described in the examples below.

[0207] In the resin composition layer of the resin sheet with a metal foil of the present invention, it usually exhibits the characteristic of excellent tackiness. Therefore, it provides a resin sheet with a metal foil having excellent handleability. Specifically, the tack 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 even more preferably less than 0.4 N. The lower limit is not particularly limited, but can be 0.01 N or more, etc. The evaluation of tackiness can be measured by the method described in the examples below.

[0208] In the resin sheet with a metal foil of the present invention, since the glass transition temperature (Tg) of the cured product of the resin composition layer is high, it usually exhibits the characteristic of excellent mechanical strength. Therefore, it provides an insulating layer with excellent mechanical strength. The resin sheet with a metal foil with the protective film removed is laminated on a copper foil such that the resin composition layer is in contact with the copper foil. After lamination, the resin composition layer is thermally cured by vacuum press treatment, the copper foil is removed, and a cured product for evaluation is obtained. Then, the cured product for evaluation is cut into test pieces with a width of 2 mm and a length of 80 mm, and the elongation at break is measured using a tensile tester. At this time, the elongation at break is preferably 3.0% or more, more preferably 4.0% or more, and even more preferably 5.0% or more. The upper limit is not particularly limited, but 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 the characteristic that the cured product of the resin composition layer has a low dielectric loss tangent. Therefore, the cured product provides an insulating layer with a low dielectric loss tangent. The dielectric loss tangent is preferably 0.01 or less, more preferably 0.009 or less, still more preferably 0.008 or less, or 0.005 or less. The lower limit is not particularly limited, and it can be 0.0001 or more, etc. The measurement of the dielectric loss tangent can be carried out according to the method described in the examples below.

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

[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 including an insulating layer made of a cured product of the resin composition layer of the resin sheet with a metal foil of the present invention and a conductor layer formed from a metal foil can be provided.

[0212] Examples of the circuit board include a printed wiring board, a semiconductor chip package, etc. The circuit board includes an insulating layer made of a cured product of the resin composition layer of the resin sheet with 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, by a method including the following steps (I) and (II) using the resin sheet with a metal foil described above. (I) A step of laminating the resin composition layer in the resin sheet with a metal foil on the inner layer substrate by vacuum pressing. (II) A step of thermosetting the resin composition layer to form an insulating layer.

[0214] The "inner layer substrate" used in step (I) is a member serving as the substrate of the circuit board, and examples thereof include a glass epoxy substrate, a metal substrate, a polyester substrate, a polyimide substrate, a BT resin substrate, a thermosetting polyphenylene ether substrate, and the like. Further, the substrate may have a conductor layer on one or both sides thereof, and this conductor layer may be pattern-processed. The inner layer substrate having a conductor layer (circuit) formed on one or both sides of the substrate may be referred to as an "inner layer circuit board". In addition, when manufacturing the circuit board, an intermediate product on which an insulating layer and / or a conductor layer is to be further formed is also included in the "inner layer substrate" referred to in the present invention. When the circuit board is a circuit board with built-in components, an inner layer substrate with built-in components can be used.

[0215] The lamination of the inner layer substrate and the resin sheet with a metal foil is performed by vacuum pressing so that the resin composition layer of the resin sheet with a metal foil is joined to the inner layer substrate after peeling the protective film.

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

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

[0218] The vacuum press treatment can be carried out using a conventionally known vacuum press apparatus that presses a resin sheet with a metal foil from which an inner layer substrate and a protective film have been peeled off from both sides thereof by a heated metal plate such as a SUS plate. Examples of commercially available vacuum press apparatuses include "VH1-1603" manufactured by Kitakawa Seiki Co., Ltd.

[0219] The vacuum press treatment may be carried out only once, or may be repeated two or more times. When carried out repeatedly two or more times, the crimping pressure, heating temperature, press time, etc. may be the same or different.

[0220] In the vacuum press treatment, the crimping pressure (pressing force) is preferably 5 kgf / cm 2 or more, more preferably 10 kgf / cm 2 or more, still more preferably 15 kgf / cm 2 or more, and preferably 50 kgf / cm 2 or less, more preferably 35 kgf / cm 2 or less, still more preferably 25 kgf / cm 2 or less.

[0221] In the vacuum press treatment, the pressure of the atmosphere, that is, the pressure (degree of vacuum) during decompression in the chamber in which the laminated structure to be treated is stored, is preferably 3×10 -2 MPa or less, more preferably 1×10 -2 MPa or less. The lower limit is not particularly limited, but may be 1×10 -10 MPa or more, etc.

[0222] In the vacuum press treatment, the heating temperature varies depending on the composition of the resin composition layer, but is preferably 80°C or more, more preferably 90°C or more, still more preferably 100°C or more. The upper limit of the heating temperature is not particularly limited, but may usually be 300°C or less, etc. Note that the resin composition layer may be thermoset by heating in the vacuum press treatment to form an insulating layer.

[0223] In the vacuum press treatment, the press time is preferably 5 minutes or more, more preferably 10 minutes or more, and even more preferably 15 minutes or more. The upper limit is not particularly limited, but is preferably 300 minutes or less, more preferably 200 minutes or less, and even more preferably 150 minutes or less.

[0224] After laminating a resin sheet with a metal foil from which the protective film has been peeled on the inner layer substrate by vacuum press treatment, in step (II), the resin composition layer is thermoset to form an insulating layer. As a method of thermosetting the resin composition layer, for example, when performing a press treatment by vacuum press treatment, a method of thermosetting the resin composition layer using the heat during pressing to form an insulating layer can be mentioned.

[0225] The thermosetting conditions of the resin composition layer are not particularly limited, and conditions usually employed when forming an insulating layer of a circuit board and a printed wiring board may be used.

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

[0227] Before thermosetting the resin composition layer, the resin composition layer may be preheated at a temperature lower than the curing temperature. For example, prior to thermosetting the resin composition layer, at a temperature of 50°C or higher and lower 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 may be preheated for 5 minutes or more (preferably 5 minutes to 150 minutes, more preferably 15 minutes to 120 minutes, and even more preferably 15 minutes to 100 minutes).

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

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

[0230] In the subtractive method, unnecessary portions (non-circuit forming portions) of the metal foil are selectively removed by etching or the like to form a circuit. Circuit formation by the subtractive method may be carried out according to a known procedure. For example, circuit formation by the subtractive method can be carried out by a method including: i) providing an etching resist on the surface of the metal foil (i.e., the surface opposite to the surface joined to the resin composition layer); ii) exposing and developing the etching resist to form a wiring pattern; iii) etching and removing the exposed metal foil portion; and iv) removing the etching resist.

[0231] In the modified semi-additive method, non-circuit forming portions of the metal foil are protected by a plating resist, a metal such as copper is thickened on the circuit forming portion by electrolytic plating, then the plating resist is removed, and the metal foil other than the circuit forming portion is removed by etching to form a circuit. Circuit formation by the modified semi-additive method may be carried out according to a known procedure. For example, circuit formation by the modified semi-additive method can be carried out by a method including: i) providing a plating resist on the surface of the metal foil (i.e., the surface opposite to the surface joined to the resin composition layer); ii) exposing and developing the plating resist to form a wiring pattern; iii) performing electrolytic plating through the plating resist; iv) removing the plating resist; and v) etching and removing the metal foil other than the circuit forming portion. When the metal foil is thick, before the above step i), the entire surface of the metal foil may be thinned by etching or the like so that the metal foil has a desired thickness (usually 5 μm or less, 4 μm or less, or 3 μm or less).

[0232] When manufacturing a circuit board, the steps of (IV) drilling holes and (V) roughening the insulating layer may be further performed. These steps (IV) to (V) may be carried out according to various methods known to those skilled in the art used for manufacturing circuit boards. Further, if necessary, the formation of the insulating layer and the conductor layer in steps (I) to (V) may be repeated to form a multilayer wiring board.

[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 semiconductor devices include various semiconductor devices used in electrical products (such as computers, mobile phones, digital cameras, and televisions, etc.) and vehicles (such as motorcycles, automobiles, trains, ships, and airplanes, etc.).

[0235] The semiconductor device of the present invention can be manufactured by mounting components (semiconductor chips) at the conductive locations of the circuit board. The "conductive location" means "the location on the circuit board that transmits electrical signals", and the location can be either the surface or an embedded location. Further, the semiconductor chip is not particularly limited as long as it is an electric circuit element made of semiconductor.

[0236] The method of mounting the semiconductor chip when manufacturing the semiconductor device is not particularly limited as long as the semiconductor chip functions effectively. Specifically, examples include wire bonding mounting method, flip chip mounting method, mounting method using bump-less build-up layer (BBUL), mounting method using anisotropic conductive film (ACF), mounting method using non-conductive film (NCF), and the like. Here, the "mounting method using bump-less build-up layer (BBUL)" means "the mounting method of directly embedding the semiconductor chip into the recess of the circuit board and connecting the semiconductor chip and the wiring on the circuit board".

Examples

[0237] Hereinafter, the present invention will be specifically described with reference to examples. The present invention is not limited to these examples. In the following, "parts" and "%" mean "parts by mass" and "mass%" respectively, unless otherwise specified.

[0238] <Synthesis Example 1: Synthesis of Polyimide 1> Into a 1000 ml separable flask equipped with a nitrogen inlet tube and a stirrer, 62.46 g (120 mmol) of 4,4'-(4,4'-isopropylidenediphenoxy)bisphtalic dianhydride (BPADA), 12.17 g (40 mmol) of (5-amino-2-biphenyl)-4-aminobenzoate (PHBAAB), 27.56 g (80 mmol) of 4,4'-(m-phenylenediisopropylidene)dianiline (Bisaniline-M), 303 g of 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 during the reaction, 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> A monomer composition obtained by mixing 49.6 g of 4,4'-(4,4'-isopropylidenediphenoxy)bisphtalic dianhydride (BPADA), 50.4 g of 4,4'-[1,4-phenylenebis[(1-methylethylidene)-4,1-phenyleneoxy]]bisbenzenamine (BPPAN), and 40 g of toluene as a solvent in 400 g of cyclohexanone (hereinafter also referred to as "Anone") as a solvent was stirred and reacted at room temperature and atmospheric pressure for 3 hours. Thereby, a polyamide solution was obtained.

[0240] Subsequently, after raising the temperature of the polyamide solution, while maintaining it at about 160 °C, azeotropic removal of the condensed water together with toluene was carried out under a nitrogen stream. It was confirmed that a predetermined amount of water had accumulated in the water metering receiver and that the outflow of water had stopped. After confirmation, the reaction solution was further heated and stirred at 200 °C for 1 hour. Then, it was cooled. As a result, a cyclohexanone solution containing 20% by mass of polyimide resin 2 as a non-volatile component was obtained.

[0241] It was presumed that polyimide resin 2 contained a structural unit represented by the following formula (a) from the above reaction route. Also, it was presumed that polyimide resin 2 contained a skeleton derived from BPADA and a skeleton derived from BPPAN from the above reaction route.

Chemical formula

[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 Publication No. 2020-500211 of the Technical Report of the Japan Institute of Invention and Innovation 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

[0243] <Manufacture of resin varnish> Each component was weighed in the number of parts by mass shown in Table 1 below and uniformly dispersed using a high-speed rotary mixer to obtain a resin varnish. In Table 1 below, the number of parts by mass of component (A-1) and component (A-2) is the total number of parts by mass of component (A-1) and component (A-2) contained in each component used as component (B) to component (G). Also, in Table 1 below, the number of parts by mass of component (B) to component (G) is the number of parts by mass of the non-volatile component.

Table 1

[0244] Details of each component described in the table are as follows. (A-1) Organic solvent 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: Ipozol, boiling point 184 - 205 °C, manufactured by Idemitsu Kosan Co., Ltd. (A-2) Organic solvent with a boiling point of 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 phenol novolak structure, functional group equivalent 125 g / eq., 60% by mass MEK solution of non-volatile content, manufactured by DIC Corporation · P-d: Benzoxazine compound, functional group equivalent 217 g / eq., manufactured by Shikoku Chemicals Corporation ·HPC-8000-65T: An active ester resin containing a dicyclopentadiene-type diphenol structure, with a functional group equivalent of 223 g / eq., a toluene solution with a non-volatile content of 65% by mass, manufactured by DIC Corporation ·V03: A carbodiimide-based curing agent, with a functional group equivalent of 216 g / eq., a toluene solution with a non-volatile content of 50% by mass, manufactured by Nisshinbo Chemicals, Inc. ·OPE-2St: Vinylbenzyl-modified polyphenylene ether, with a functional group equivalent of 590 g / eq., manufactured by Mitsubishi Gas Chemical Company ·Maleimide A: The maleimide synthesized in Synthesis Example 3 ·A-DOG: A polyfunctional acrylate, with a functional group equivalent of 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 (Shin-Etsu Chemical Co., Ltd.'s "KBM573"), with an average particle size of 0.5 μm and a specific surface area of 5.8 m 2 / g, manufactured by Admatechs Co., Ltd. (D) Flexible resin ·Polyimide 1: The polyimide synthesized in Synthesis Example 1 ·Polyimide 2: The polyimide synthesized in Synthesis Example 2 (E) Phenoxy resin ·YX7553BH30: A phenoxy resin, a 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: A phosphorus-containing phenolic flame retardant, manufactured by Sanko Chemical Industries, Ltd. (G) Curing accelerator ·1B2PZ: Manufactured by Shikoku Kasei Kogyo Co., Ltd.

[0245] (Production of resin sheet with metal foil) The resin varnishes obtained in the examples and comparative examples were applied onto the release surface of a polyethylene terephthalate film with a release treatment (Toray Industries, Inc.'s "Lumirror R80, thickness 38 μm") serving as a support using a die coater so that the thickness of the resin composition layer became 40 μm, and dried under the drying conditions described in the above table. Subsequently, a copper foil with a carrier having a carrier copper foil and an ultra-thin copper foil (Mitsui Mining & Smelting Co., Ltd.'s "Micro Shin MT18Ex", ultra-thin copper foil with a thickness of 3 μm / carrier copper foil with a thickness of 18 μm) was laminated onto the surface of the resin composition layer using a roll laminator (manufactured by Daisheng Laminator Co., Ltd., "FIRST LAMINATOR VA-770H") at a roll pressure of 0.25 MPa, a feed rate of 0.3 m / min, and a roll temperature of 90°C to obtain a resin sheet with a metal foil.

[0246] <Measurement of the content rate of the organic solvent (residual solvent amount) in the resin composition layer> A part (5 mg) of the resin composition layer was measured from the resin sheets with a metal foil prepared in the examples and comparative examples, and the sample measured under the oven conditions of 250°C for 10 minutes using GCMS-QP2020-NX (manufactured by Shimadzu Corporation) was processed, and measured under the conditions of a sample line temperature of 260°C, a transfer line temperature of 260°C, and a cycle time of 55 minutes. The solvent species were specified from each detected peak, and by comparing with a calibration curve prepared in advance, the types and contents of the organic solvents contained in the resin composition layer of the resin sheet with a metal foil were analyzed.

[0247] <Measurement of the weight loss rate> The resin sheets with metal foils prepared in the examples and comparative examples were cut into 10 cm × 10 cm pieces, which were placed in a desiccator together with sufficiently dried silica gel and left for 30 minutes. Then, the mass (g) of the resin sheet with metal foil was measured, and the value was designated as α1 (g). Next, the resin sheet with metal foil was heated in an oven at 200°C for 30 minutes, and after being left to cool in the desiccator for 30 minutes in the same manner as before, the mass (g) of the resin sheet with metal foil was measured again, and the value was designated as α2 (g). Also, only the metal foil was cut into 10 cm × 10 cm pieces, and after being left in the desiccator for 30 minutes, the mass (g) of the metal foil was measured, and the value was designated as β (g). The value of the weight loss rate α (%) of the resin composition layer when the resin sheet with metal foil was heat-treated at 200°C for 30 minutes was calculated from the following formula (A).

Equation

[0248] <Evaluation of Film Flexibility> The resin sheet with metal foil was cut with a temporary fixing device, and cracks and chips at the cut edge ends were visually confirmed Then, based on the following evaluation criteria, the resin chips were evaluated. 〇: There are no cracks or chips in the resin sheet with metal foil. ×: There are cracks or chips in the resin sheet with metal foil.

[0249] <Evaluation of Tackiness> The tack force was measured using a probe tack tester with a thermostat (manufactured by Tester Sangyo Co., Ltd., TE-6002). A SUS-made 5 mmφ cylindrical probe was brought into contact with the resin sheet with metal foil placed in a thermostat at 25°C at a contact speed of 0.5 cm / second, and after being held for 1 second under a load of 1000 gf / cm 2 the peel force when the probe was pulled away at 0.5 cm / second was measured and taken as the probe tack. The measurement was performed 3 times for each sample, and the average value in each measurement was obtained and evaluated according to the following criteria. 〇: The peel force is less than 0.4 N. △: The peel force is 0.4 or more and less than 0.6 N. ×: The peel force is 0.6 or more.

[0250] <Preparation of Cured Product for Evaluation by Vacuum Press Curing> From the resin sheets with metal foils obtained in the examples and comparative examples, the support was peeled off, and another copper foil ("Microcin MT18Ex" manufactured by Mitsui Mining & Smelting Co., Ltd.) was overlaid so that the resin composition layer was in contact. Using a vacuum hot press machine (VH1-1603 manufactured by Kitakawa Seiki Co., Ltd.), the degree of vacuum during pressing was 1×10 -3 MPa or less, and the pressure condition was 20 kgf / cm 2 The resin composition layer was thermally cured under the heating conditions that the first-stage pressing had a temperature of 100°C for 30 minutes and the second-stage pressing had a temperature of 190°C for 120 minutes. The thermally cured resin sheet with metal foil was immersed in an aqueous solution of iron(II) chloride (manufactured by Tsurumi Soda Co., Ltd., Baumé degree 40), and after removing the copper foil, it was dried at 130°C for 15 minutes to obtain a sheet-shaped cured product. The obtained cured product is referred to as "Cured Product for Evaluation by Vacuum Press Curing".

[0251] <Measurement of Dielectric Constant and Dielectric Loss Tangent of Cured Product for Evaluation by Vacuum Press Curing> The cured product for evaluation by vacuum press curing was cut into test pieces with a width of 2 mm and a length of 80 mm. For the test pieces, using "HP8362B" manufactured by Agilent Technologies, the dielectric loss tangent was measured at a measurement frequency of 5.8 GHz and a measurement temperature of 23°C by the cavity resonance perturbation method. Measurements were performed on two test pieces and the average value was calculated.

[0252] <Measurement of Glass Transition Temperature of Cured Product for Evaluation by Vacuum Press Curing> The cured product for evaluation by vacuum press 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 by the tensile loading method using a dynamic viscoelasticity measuring device (EXSTAR6000, manufactured by SII NanoTechnology Inc.). After mounting the test pieces on the device, measurements were performed under the measurement conditions of a load of 200 mN and a heating rate of 2°C / min. The peak top of the obtained tanδ was calculated as the glass transition temperature (°C) and evaluated according to the following criteria. 〇: The glass transition temperature is 160°C or higher. △: The glass transition temperature is 150°C or higher and less than 160°C ×: The glass transition temperature is less than 150°C

[0253] <Measurement of Mechanical Strength of Cured Product for Evaluation by Vacuum Press Curing> The cured product for evaluation by vacuum press curing was subjected to a tensile strength measurement using a tensile testing machine "RTC-1250A" manufactured by Orientec Co., Ltd., and the elongation at break at 23 °C was measured. The measurement was carried out in accordance with JIS K7127. The measurement was performed 5 times, the average value of the top 3 points was calculated, and the evaluation was made 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

[0255] Since the resin composition layers in Examples 1 to 12 contain either a carbodiimide resin or a polyimide resin, it has been confirmed that the adhesion to the metal foil is also excellent.

Claims

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

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

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

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

5. The resin sheet with a 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 a metal foil according to claim 1, wherein the component (A-1) contains either a carbon-oxygen double bond or a carbon-sulfur double bond.

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

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

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

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

11. A circuit board comprising: an insulating layer formed from a cured product of a resin composition layer of the resin sheet with a metal foil according to any one of claims 1 to 10; and a conductor layer formed from the metal foil of the resin sheet with a metal foil according to any one of claims 1 to 10.

12. A semiconductor device comprising the circuit board according to claim 11.

13. (I) a step of laminating a resin composition layer of the resin sheet with a metal foil according to any one of claims 1 to 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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