Laminated structure, method for producing same, cured product, and electronic component

Abstract

Provided is a laminated structure which is capable of forming a cured product having a low-roughness surface, excellent plating adhesion, and excellent heat resistance. This laminated structure is provided with a first film and a resin layer provided on the first film, and is characterized in that the resin layer contains (A) an epoxy resin, (B) a polyarylate compound having a bisphenol structure and an ester group, (C) an inorganic filler, and (D) a solvent, and that the resin layer contains 38-82% by mass of the (C) inorganic filler in terms of solid content. The weight loss ratio of the resin layer after being heated for 20 minutes at a temperature of 100 DEG C under atmospheric pressure is 3.0 mass% or less.

Description

Technical Field

[0001] The present invention relates to a laminated structure, and more particularly, to a laminated structure including a resin layer formed using a curable resin composition suitably used for electronic components such as printed circuit boards, a method for manufacturing the same, a cured product, and an electronic component. Background Art

[0002] With the miniaturization and high performance of electronic devices, for multilayer printed circuit boards, higher lamination and higher density of laminated layers are also required. The additive method and semi-additive method of forming a conductor layer on the surface of an insulating layer by plating treatment have become mainstream, and an insulating layer material capable of ensuring adhesion to the plated conductor layer is sought.

[0003] Therefore, for example, in the use of an interlayer insulating material for electronic components, a resin composition capable of forming a cured product having excellent adhesion to a plating layer is required. In response to this requirement, for example, Patent Document 1 proposes a thermosetting epoxy resin composition that can form a roughened surface having excellent adhesion to a plating layer by adding a specified amount of an active ester compound containing a naphthalene structure to an epoxy resin. In addition, as another aspect of the thermosetting epoxy resin composition, an adhesive film for forming an insulating layer of a laminated structure including a resin layer formed from the thermosetting epoxy resin composition is also proposed.

[0004] Prior Art Documents

[0005] Patent Documents

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 2014-47318 Summary of the Invention

[0007] Problems to be Solved by the Invention

[0008] However, for the thermosetting epoxy resin composition using an active ester compound containing a naphthalene structure proposed in Patent Document 1, a cured product having a glass transition temperature of 180°C or higher cannot be obtained, and the heat resistance is insufficient. In order to improve the heat resistance, as a method of increasing the glass transition temperature without changing the resin type, an operation of increasing the crosslink density of the cured product is generally performed. The present inventors conducted various studies and determined that when the blending ratio of the active ester compound containing a naphthalene structure is increased to increase the crosslink density, the glass transition temperature becomes higher and the heat resistance is improved, but the adhesion to the plating layer is reduced.

[0009] Therefore, the main object of the present invention is made in view of the above problems, and the object is to provide a laminated structure capable of forming a cured product having a low surface roughness, excellent adhesion to a plating layer, and excellent heat resistance. Another object of the present invention is to provide a method for manufacturing the laminated structure, a cured product, and an electronic component.

[0010] Solution for solving problems

[0011] The inventors further advanced the research and as a result obtained the following insight: The surface roughness of the cured product and the reduction of the coating adhesion also affect the weight loss rate after heating the resin layer in the laminated structure under specified conditions. The present invention is based on the above insight. That is, the gist of the present invention is as described below.

[0012] [1] A laminated structure, characterized by comprising: a first thin film, and a resin layer provided on the aforementioned first thin film,

[0013] The aforementioned resin layer contains:

[0014] (A) Epoxy resin,

[0015] (B) A polyarylate compound having a bisphenol structure and an ester group,

[0016] (C) Inorganic filler, and

[0017] (D) Solvent,

[0018] In the aforementioned resin layer, the aforementioned (C) inorganic filler is contained in an amount of 38 to 82% by mass based on the solid content,

[0019] The weight loss rate of the aforementioned resin layer after heating the resin layer at a temperature of 100 °C for 20 minutes under atmospheric pressure is 3.0% by mass or less.

[0020] [2] The laminated structure according to [1], wherein the weight loss rate of the aforementioned resin layer after heating the resin layer at a temperature of 100 °C for 20 minutes is 2.0% by mass or less.

[0021] [3] The laminated structure according to [1] or [2], wherein the aforementioned resin layer substantially does not contain a photoinitiator and a photopolymerizable compound.

[0022] [4] A method for manufacturing a laminated structure, which is a method for manufacturing the laminated structure according to any one of [1] to [3], and the manufacturing method includes the following steps:

[0023] Prepare a curable resin composition, the curable resin composition contains (A) epoxy resin, (B) a polyarylate compound having a bisphenol structure and an ester group, (C) inorganic filler and (D) solvent, and the aforementioned (C) inorganic filler is contained in an amount of 38 to 82% by mass based on the solid content in the aforementioned resin layer;

[0024] Coat the aforementioned curable resin composition on one surface of the first thin film to form a coating film;

[0025] The aforementioned coating film is dried at a temperature of 60 to 180°C for 1 to 30 minutes to form a resin layer.

[0026] [5] A cured product which is a cured product of the resin layer of the laminated structure according to any one of [1] to [3].

[0027] [6] An electronic component which has the cured product according to [5].

[0028] Effects of the Invention

[0029] According to the present invention, in a laminated structure having a resin layer containing an epoxy resin, a polyarylate compound having a bisphenol structure and an ester group, a specified amount of an inorganic filler, and a solvent, a resin layer is formed such that the weight loss rate after heating under specified conditions is 3.0 mass% or less, whereby a laminated structure capable of forming a cured product having a surface with low roughness, excellent plating adhesion, and excellent heat resistance can be achieved. Further, according to the laminated structure of the present invention, a cured product having a surface roughness lower than 0.30 μm, further lower than 0.20 μm, a peel strength from a plating of 3.0 N / cm or more, further 3.5 N / cm or more, and a glass transition temperature of 180°C or more, further 190°C or more can be obtained. Detailed Description of the Invention

[0030] <Laminated Structure>

[0031] The laminated structure of the present invention includes: a first thin film, and a resin layer provided on the first thin film. The resin layer contains: (A) an epoxy resin, (B) a polyarylate compound having a bisphenol structure and an ester group, a specified amount of (C) an inorganic filler, and (D) a solvent. The resin layer constituting the laminated structure is formed as follows: a curable resin composition containing the above components is coated on one surface of the first thin film to form a coating film, and it is usually dried at a temperature of 60 to 180°C for 1 to 30 minutes, thereby forming. In the present invention, the weight loss rate when the formed resin layer is heated at 100°C under atmospheric pressure for 20 minutes (that is, (the mass of the resin layer before heating - the mass of the resin layer after heating) / the mass of the resin layer before heating × 100) is 3.0% by mass or less. Thus, by forming a resin layer containing a specified amount of an inorganic filler and having a weight loss rate of 3.0% by mass or less after heating, a laminated structure capable of obtaining a cured product having a low-roughness surface, excellent plating adhesion, and excellent heat resistance can be formed. That is, it is considered that the volatile components contained in the resin layer become factors hindering curing under specific conditions. As a result, it is considered that, as in the present invention, in the resin layer containing a specified amount of an inorganic filler, the weight loss rate after heating is 3.0% by mass or less, so that the curing reaction proceeds moderately, and thus the effects of the present invention are suitably obtained. As volatile components, trace solvents, silane coupling agents, etc. are considered. However, the above mechanism is only the speculation of the present inventors and is not necessarily limited to this theory.

[0032] The weight loss rate of the resin layer after heating can be adjusted according to the material types, compounding ratios, drying temperature, drying time, etc. of the respective components contained in the curable resin composition described later. The weight loss rate (hereinafter, sometimes simply referred to as "weight loss rate") when the resin layer is heated at 100°C for 20 minutes is preferably 2.5% by mass or less, more preferably 2.0% by mass or less. In addition, since the resin layer of the laminated structure of the present invention contains (D) a solvent, the lower limit value of the weight loss rate is theoretically considered not to be 0% by mass, and exceeding 0% by mass, for example, can be 0.5% by mass or more, or can be 1.0% by mass or more. Hereinafter, the curable resin composition for forming the resin layer will be described.

[0033] <Curable Resin Composition>

[0034] The resin layer constituting the laminated structure of the present invention contains (A) an epoxy resin, (B) a polyarylate compound having a bisphenol structure and an ester group, (C) an inorganic filler, and (D) a solvent as essential components. By heating the resin layer, (A) the epoxy resin and (B) the polyarylate compound having a bisphenol structure and an ester group react to form a cured product, and substantially does not contain a photoinitiator and a photopolymerizable compound.

[0035] [(A) Epoxy Resin]

[0036] The resin layer constituting the laminated structure of the present invention contains (A) an epoxy resin. As the epoxy resin, any thermosetting resin having an epoxy group in one molecule can be used without limitation, and it is, for example, one having an epoxy equivalent of less than 2000 g / eq. Examples of the (A) epoxy resin include: bisphenol A type epoxy resin, bisphenol F type epoxy resin, hydrogenated bisphenol A type epoxy resin, brominated bisphenol A type epoxy resin, bisphenol S type epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin, novolac type epoxy resin of bisphenol A, biphenyl type epoxy resin, naphthol type epoxy resin, naphthalene type epoxy resin, dicyclopentadiene type epoxy resin, triphenylmethane type epoxy resin, alicyclic epoxy resin, aliphatic chain type epoxy resin, phosphorus-containing epoxy resin, anthracene type epoxy resin, norbornene type epoxy resin, adamantane type epoxy resin, fluorene type epoxy resin, aminophenol type epoxy resin, aminocresol type epoxy resin, alkylphenol type epoxy resin, etc. These (A) epoxy resins can be used alone or in combination of two or more. The (A) epoxy resin preferably contains at least one of bisphenol A type epoxy resin, bisphenol F type epoxy resin, and biphenyl novolac type epoxy resin, and particularly preferably contains bisphenol A type epoxy resin. By containing bisphenol A type epoxy resin, the heat resistance of the cured product and the adhesion to the second film become good.

[0037] (A) Among the epoxy resins, there are solid, semi-solid, and liquid epoxy resins. It should be noted that "liquid" means a state of being liquid with fluidity at 20°C, "semi-solid" means a solid state without fluidity at 20°C but a liquid state with fluidity at 40°C, and "solid" means a solid state without fluidity at 20°C and 40°C.

[0038] Examples of solid epoxy resins include: epoxides of condensates of phenols and aromatic aldehydes having phenolic hydroxyl groups (trisphenol type epoxy resins) such as EPPN-502H (trisphenol epoxy resin) manufactured by Nippon Kayaku Co., Ltd.; dicyclopentadiene aralkyl type epoxy resins such as EPICLON (registered trademark) HP-7200H (multifunctional solid epoxy resin containing dicyclopentadiene skeleton) manufactured by DIC Corporation; biphenyl aralkyl type epoxy resins such as NC-3000H and NC-3000L (biphenol novolak type epoxy resins) manufactured by Nippon Kayaku Co., Ltd.; novolak type epoxy resins such as EPICLON (registered trademark) N660, EPICLON (registered trademark) N690 manufactured by DIC Corporation and EOCN-104S manufactured by Nippon Kayaku Co., Ltd.; phenol novolak type epoxy resins such as D.E.N. 431 manufactured by Dow Chemical Company; biphenyl type epoxy resins such as YX-4000 manufactured by Mitsubishi Chemical Corporation; phosphorus-containing epoxy resins such as TX0712 manufactured by NIPPON STEEL Chemical & Material Co., Ltd.; tris(2,3-epoxypropyl) isocyanurate such as TEPIC manufactured by Nissan Chemical Industries, Ltd.; bisphenol A type epoxy resins such as jER (registered trademark) 1001 manufactured by Mitsubishi Chemical Corporation, etc.

[0039] Examples of semi-solid epoxy resins include: bisphenol A type epoxy resins such as EPICLON (registered trademark) 860, EPICLON (registered trademark) 900-IM, EPICLON (registered trademark) EXA-4816, EPICLON (registered trademark) EXA-4822 manufactured by DIC Corporation, EPOTOHTO YD-134 manufactured by NIPPONSTEEL Chemical & Material Co., Ltd., jER (registered trademark) 834 and jER (registered trademark) 872 manufactured by Mitsubishi Chemical Corporation, and ELA-134 manufactured by Sumitomo Chemical Co., Ltd.; novolak type epoxy resins such as EPICLON (registered trademark) N-740 manufactured by DIC Corporation, etc.

[0040] Examples of the liquid epoxy resin include: ZX-1059 manufactured by NIPPON STEEL Chemical&Material Co.,Ltd. (a mixture of bisphenol A type and bisphenol F type epoxy resins), jER (registered trademark) 828 manufactured by Mitsubishi Chemical Corporation (bisphenol A type epoxy resin), jER (registered trademark) 807 manufactured by Mitsubishi Chemical Corporation, jER (registered trademark) 4004P manufactured by Mitsubishi Chemical Corporation (bisphenol F type epoxy resin), EP-3300E manufactured by ADEKA Corporation (hydroxybenzophenone type liquid epoxy resin), jER (registered trademark) 630 manufactured by Mitsubishi Chemical Corporation (aminophenol type liquid epoxy resin), ELM-100 manufactured by Sumitomo Chemical Co.,Ltd. (p-aminophenol type liquid epoxy resin), etc.

[0041] [(B) Polyarylate compound having a bisphenol structure and an ester group]

[0042] The resin layer constituting the laminated structure of the present invention contains: (B) a polyarylate compound having a bisphenol structure and an ester group, which also functions as a curing agent for the above-mentioned (A) epoxy resin. The (B) polyarylate compound having a bisphenol structure and an ester group is a polymer obtained by polycondensing a binary bisphenol component and a binary aromatic carboxylic acid component.

[0043] As the binary bisphenol component, any compound containing two phenolic hydroxyl groups in one molecule can be used without particular limitation, and the compound represented by the following formula (1) can be suitably used.

[0044]

[0045] In the above formula (1), X 1 ~X 4 each independently represents a hydrogen atom, a hydrocarbon group having 1 to 12 carbon atoms or a halogen atom, and Y represents a linear or branched alkylene group having 1 to 20 carbon atoms which may optionally have a substituent. Examples of the substituent include a cyclic hydrocarbon group containing an aromatic and an alicyclic group, a trihalomethane group, an alkyl ester group, and a phenyl ester group.

[0046] Among the above, as the binary bisphenol component, the compound represented by the following formula (2) can be preferably used.

[0047]

[0048] In the above formula (2), X 1 ~X 4 each independently represents a hydrogen atom, a saturated aliphatic hydrocarbon group having 1 to 12 carbon atoms, an unsaturated aliphatic hydrocarbon group having 2 to 6 carbon atoms or an aromatic hydrocarbon group having 6 to 10 carbon atoms, or a halogen atom. X 1 ~X 4When it is a saturated aliphatic hydrocarbon group, it is preferably an alkyl group having 1 to 6 carbon atoms, more preferably an alkyl group having 1 to 3 carbon atoms. Examples of the saturated aliphatic hydrocarbon group include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, and n-hexyl. X 1 ~X 4 When it is an unsaturated aliphatic hydrocarbon group, it is preferably an alkenyl group having 2 to 3 carbon atoms. Examples of the unsaturated aliphatic hydrocarbon group include vinyl and allyl. X 1 ~X 4 When it is an aromatic hydrocarbon group, it is preferably an aryl group having 6 to 10 carbon atoms. Examples of the aromatic hydrocarbon group include phenyl and naphthyl. In addition, examples of the halogen atom include fluorine atom, chlorine atom, bromine atom, and iodine atom, and chlorine atom and bromine atom are preferred.

[0049] X 1 ~X 4 They are preferably the same group. In addition, preferred X 1 ~X 4 is a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an aryl group having 6 to 10 carbon atoms, or a halogen atom.

[0050] In the above formula (2), Y 1 represents a carbon atom that forms a saturated aliphatic hydrocarbon ring (monocyclic ring) together with the carbon atom to which the hydroxyphenyl group is bonded. The saturated aliphatic hydrocarbon ring represents a cycloalkane ring corresponding to the number of m. Examples of the saturated aliphatic hydrocarbon ring include a cyclopentane ring (m = 4), a cyclohexane ring (m = 5), and a cycloheptane ring (m = 6).

[0051] In the above formula (2), R 1 and R 2 each independently represent a hydrogen atom or a hydrocarbon group. The hydrocarbon group may be a saturated aliphatic hydrocarbon group having 1 to 4 carbon atoms or an unsaturated aliphatic hydrocarbon group having 2 to 4 carbon atoms. The saturated aliphatic hydrocarbon group is preferably an alkyl group having 1 to 3 carbon atoms. Examples of the saturated aliphatic hydrocarbon group include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, and tert-butyl. The unsaturated aliphatic hydrocarbon group is preferably an alkenyl group having 2 to 3 carbon atoms. Examples of the unsaturated aliphatic hydrocarbon group include vinyl and allyl. R 1 and R 2 exist in plural according to the value of m, and these plural R 1 and R 2 can each independently be selected from the above ranges, and a hydrogen atom or an alkyl group having 1 to 4 carbon atoms is preferred. In the above formula (2), m is an integer of 4 to 11, and 4 or 5 is preferred.

[0052] The binary aromatic carboxylic acid component may be used without particular limitation as long as it is a compound having two carboxyl groups directly bonded to an aromatic ring in one molecule, and terephthalic acid, isophthalic acid, phthalic acid, 4,4'-diphenyldicarboxylic acid, diphenyl ether-2,2'-dicarboxylic acid, diphenyl ether-2,3'-dicarboxylic acid, diphenyl ether-2,4'-dicarboxylic acid, diphenyl ether-3,3'-dicarboxylic acid, diphenyl ether-3,4'-dicarboxylic acid, diphenyl ether-4,4'-dicarboxylic acid, 2,6-naphthalenedicarboxylic acid may be preferably used. The above binary aromatic carboxylic acid component may be used alone or in combination of two or more.

[0053] In the present invention, a polyarylate compound having a bisphenol structure and an ester group represented by the following formula (3) obtained by polycondensing the binary bisphenol component shown in the above formula (1) and terephthalic acid, isophthalic acid or phthalic acid as the binary aromatic carboxylic acid component may also be used. It should be noted that X in the formula (3) 1 ~X 4 and Y represent the same as X in the above formula (1) 1 ~X 4 and Y, and n represents a repeating unit.

[0054]

[0055] (B) The polyarylate compound having a bisphenol structure and an ester group can be obtained by polycondensing a binary bisphenol component and a binary aromatic carboxylic acid component. The polycondensation reaction is usually carried out under reduced pressure of 130 Pa or less and at a temperature of 220 to 280 °C using a polymerization catalyst. As the polymerization catalyst, for example, titanium compounds such as tetrabutyl titanate; metal acetates such as zinc acetate, magnesium acetate, zinc acetate; antimony trioxide; organotin compounds such as hydroxybutyltin oxide, tin octanoate can be cited.

[0056] The number average molecular weight of the (B) polyarylate compound having a bisphenol structure and an ester group obtained as described above is not particularly limited, and is, for example, 1000 to 100000. It should be noted that the number average molecular weight can be measured by gel permeation chromatography (GPC) according to a general method.

[0057] In addition, the functional group equivalent (equivalent derived from the content of the ester group and phenolic hydroxyl group) of the (B) polyarylate compound having a bisphenol structure and an ester group is, for example, 150 to 350 g / eq.

[0058] (B) The terminals of the polyarylate compound having a bisphenol structure and an ester group can be capped with a capping agent. As a method for obtaining the capped polyarylate compound, a conventionally well-known method can be adopted. For example, it can be a method of mixing a binary bisphenol component, a binary aromatic carboxylic acid component, and a capping agent and carrying out polycondensation, or it can be a method of carrying out polycondensation of a binary bisphenol component and a binary aromatic carboxylic acid component and then reacting the capping agent.

[0059] As the capping agent, for example, monohydric phenols, monohydric acid chlorides, monohydric alcohols, and monohydric carboxylic acids can be cited. As monohydric phenols, for example, phenol, o-cresol, m-cresol, p-cresol, p-tert-butylphenol [PTBP], o-phenylphenol, m-phenylphenol, p-phenylphenol, o-methoxyphenol, m-methoxyphenol, p-methoxyphenol, 2,3,6-trimethylphenol, 2,3-xylenol, 2,4-xylenol, 2,5-xylenol, 2,6-xylenol, 3,4-xylenol, 3,5-xylenol, 2-phenyl-2-(4-hydroxyphenyl)propane, 2-phenyl-2-(2-hydroxyphenyl)propane, 2-phenyl-2-(3-hydroxyphenyl)propane can be cited. As monohydric acid chlorides, for example, benzoyl chloride, benzenesulfonyl chloride, phenyl chloroformate can be cited. As monohydric alcohols, for example, methanol, ethanol, n-propanol, isopropanol, n-butanol, 2-butanol, pentanol, hexanol, dodecanol, stearyl alcohol, benzyl alcohol, phenethyl alcohol can be cited. As monohydric carboxylic acids, for example, acetic acid, propionic acid, octanoic acid, cyclohexanecarboxylic acid, benzoic acid, toluic acid, phenylacetic acid, p-tert-butylbenzoic acid, p-methoxyphenylacetic acid can be cited.

[0060] The above-mentioned (B) polyarylate compound having a bisphenol structure and an ester group can also use commercially available products, such as Unifiner (registered trademark) M-2000H, M-2040, V-575, W-575 (manufactured by UNITIKA LTD.), Zylon (registered trademark) 200H, 240V, 300H, 340V, 400H, 500H (manufactured by Asahi Glass Co., Ltd.), etc. They can be used alone as one kind, or two or more kinds can be used in combination.

[0061] (B) The polyarylate compound having a bisphenol structure and an ester group is preferably contained in the resin layer of the laminated structure in such a manner that the ratio of the equivalent derived from the content of the epoxy groups contained in (A) the epoxy resin to the equivalent derived from the content of the ester groups and phenolic hydroxyl groups contained in (B) the polyarylate compound having a bisphenol structure and an ester group is 0.10 to 1.20, and a more preferable range is 0.30 to 1.00. (B) The polyarylate compound having a bisphenol structure and an ester group can be used alone or in combination of two or more kinds.

[0062] [(C) Inorganic filler]

[0063] The resin layer constituting the laminated structure of the present invention contains a specified amount of (C) inorganic filler in addition to the above resin. In the present invention, as described above, together with (A) an epoxy resin and (B) a polyarylate compound having a bisphenol structure and an ester group, a specified proportion of inorganic filler is contained in the resin layer, whereby the surface roughness of the cured product formed from the laminated structure can be reduced, and the plating adhesion and heat resistance can be achieved in high dimensions. In the present invention, the (C) inorganic filler must be contained in the resin layer of the laminated structure in an amount of 38 to 82% by mass based on the solid content, preferably 38 to 75% by mass, more preferably 38 to 72% by mass.

[0064] As the (C) inorganic filler, conventionally known substances can be used without limitation. For example, silica, barium sulfate, calcium carbonate, silicon nitride, aluminum nitride, boron nitride, alumina, magnesia, aluminum hydroxide, magnesium hydroxide, titanium oxide, mica, talc, barium titanate, clay, Noyport silica particles, boehmite, magnesium carbonate, calcium zirconate and other non-metallic fillers, copper, gold, platinum, silver, palladium, silicon, alloys, ferrites, tin, zinc, nickel, aluminum, iron, cobalt and other metal fillers can be cited. The above inorganic fillers can be used alone or in combination of two or more.

[0065] In the (C) inorganic filler, from the viewpoint of reducing the surface roughness of the cured product and simultaneously exhibiting plating adhesion and heat resistance in high dimensions, silica is preferably used. As the silica, it can be amorphous, crystalline, or a mixture thereof.

[0066] The shape of the (C) inorganic filler is not particularly limited, and examples include spherical, needle-like, plate-like, scaly, hollow, amorphous, hexagonal, cubic, flaky shapes.

[0067] From the viewpoint of dispersibility and the like, the average particle size of the (C) inorganic filler is, for example, 0.1 μm to 25 μm, preferably 0.1 μm to 15 μm, more preferably 1 μm to 10 μm. It should be noted that the average particle size refers to the D50 value when making a particle size distribution based on volume, and can be obtained by a laser diffraction particle size distribution measuring device or a measuring device based on the dynamic light scattering method. As a measuring device based on the laser diffraction method, MicrotracMT3300EXII manufactured by MicrotracBEL Corp. can be cited, and as a measuring device based on the dynamic light scattering method, Nanotrac Wave II UT151 manufactured by MicrotracBEL Corp. can be cited. The measurement sample is preferably a sample in which the (C) inorganic filler is dispersed in PMA (propylene glycol monomethyl ether acetate).

[0068] In addition, considering the dispersibility of the inorganic filler (C), etc., surface treatment can be performed on the surface of the inorganic filler. As the surface treatment, surface treatments that do not introduce organic groups, such as surface treatment based on a coupling agent and alumina treatment, can be carried out. The surface treatment method of the inorganic filler (C) is not particularly limited, and a publicly known and commonly used method can be used. It is sufficient to treat the surface of the inorganic filler (C) with a surface treatment agent having a curable reactive group, such as a coupling agent having a curable reactive group.

[0069] As the coupling agent, coupling agents such as silane-based, titanate-based, aluminate-based, and zirconium aluminate-based coupling agents can be used. Among them, silane-based coupling agents are preferred. Examples of the above silane-based coupling agents include vinylsilane-based coupling agents such as vinyltrimethoxysilane and vinyltriethoxysilane, aminosilane-based coupling agents such as N-(2-aminomethyl)-3-aminopropylmethyldimethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-anilinopropyltrimethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, epoxy silane-based coupling agents such as 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, (meth)acryloylsilane-based coupling agents such as 3-methacryloyloxypropyltrimethoxysilane, and mercapto silane-based coupling agents such as 3-mercaptopropyltrimethoxysilane. They can be used alone or in combination. These silane-based coupling agents are preferably immobilized on the surface of the inorganic filler (C) in advance by adsorption or reaction. The treatment amount of the coupling agent relative to 100 parts by mass of the inorganic filler is, for example, 0.1 to 10 parts by mass.

[0070] As the curable reactive group, a thermosetting reactive group is preferred. As the thermosetting reactive group, hydroxyl group, carboxyl group, isocyanate group, amino group, imino group, epoxy group, oxetanyl group, mercapto group, oxazoline group, etc. can be cited. Among them, any at least one of amino group and epoxy group is preferred.

[0071] The surface-treated (C) inorganic filler only needs to be included in the curable resin composition in a surface-treated state. That is, the inorganic filler and the surface treatment agent can be separately compounded in the curable resin composition, and the inorganic filler can be surface-treated in the curable resin composition. It is preferred to compound the pre-surface-treated inorganic filler. By compounding the pre-surface-treated inorganic filler, it is possible to prevent a decrease in crack resistance and the like caused by the surface treatment agent that may remain unconsumed in the surface treatment during separate compounding. In the case of pre-surface treatment, it is preferred to compound a pre-dispersion liquid in which the inorganic filler is pre-dispersed in a solvent or a resin. More preferably, the surface-treated inorganic filler is pre-dispersed in a solvent, and this pre-dispersion liquid is compounded in the composition, or when the surface-untreated inorganic filler is pre-dispersed in a solvent, after sufficient surface treatment, the pre-dispersion liquid is compounded in the composition.

[0072] (C) The inorganic filler can be compounded with an epoxy resin or the like in a powder or solid state, or can be mixed with a solvent and a dispersant to form a slurry and then compounded with an epoxy resin or the like. (C) The inorganic filler can be used singly or in combination of two or more.

[0073] [Phenoxy resin]

[0074] From the viewpoint of improving the mechanical strength of the cured product, the resin layer constituting the laminated structure of the present invention may further contain a phenoxy resin as a thermoplastic resin.

[0075] Examples of the phenoxy resin include: a phenoxy resin which is a condensate of epichlorohydrin and various difunctional phenol compounds, or a phenoxy resin obtained by esterifying the hydroxyl groups of the hydroxyl ether moiety existing in its skeleton with various acid anhydrides and acyl chlorides, etc., and the epoxy equivalent is, for example, 2000 g / eq. or more. Among these, a phenoxy resin having a bisphenol skeleton is preferred. By containing a bisphenol skeleton in the phenoxy resin, it is possible to suitably obtain a cured product having a high glass transition temperature, high plating adhesion, and a low surface roughness.

[0076] Specific examples of the phenoxy resin include FX280S, FX293 manufactured by NIPPON STEEL Chemical&Material Co.,Ltd., jER (registered trademark) YX8100BH30, jER (registered trademark) YX6954BH30, jER (registered trademark) YL6974, jER (registered trademark) YX7200B35, jER (registered trademark) 1256B40 manufactured by Mitsubishi Chemical Corporation, etc. The phenoxy resin can be used singly or in combination of two or more.

[0077] The compounding ratio of the phenoxy resin is preferably 0.1 to 20% by mass, more preferably 1.0 to 10% by mass, based on the solid content in the resin layer. One kind of phenoxy resin or a combination of two or more kinds can be used.

[0078] [Curing accelerator]

[0079] In the resin layer constituting the laminated structure of the present invention, in addition to the above components, a curing accelerator may also be included. The curing accelerator can be used to mainly promote the reaction between (A) an epoxy resin and (B) a polyarylate compound having a bisphenol structure and an ester group.

[0080] Examples of the curing accelerator include: imidazoles such as imidazole, 2-methylimidazole, 2-ethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 4-phenylimidazole, 1-cyanoethyl-2-phenylimidazole, 1-(2-cyanoethyl)-2-ethyl-4-methylimidazole; guanamines such as methylguanamine and benzoguanamine; polyamines such as diaminodiphenylmethane, m-phenylenediamine, m-xylylenediamine, diaminodiphenylsulfone, dicyandiamide, urea, urea derivatives, melamine, and polyhydrazides; their organic acid salts and / or epoxy adducts; amine complexes of boron trifluoride; triazine derivatives such as ethyldiamino-s-triazine, 2,4-diamino-s-triazine, 2,4-diamino-6-dimethylphenyl-s-triazine; amines such as trimethylamine, triethanolamine, N,N-dimethyloctylamine, N-benzyldimethylamine, pyridine, dimethylaminopyridine, N-methylmorpholine, hexakis(N-methyl)melamine, 2,4,6-tris(dimethylaminophenol), tetramethylguanidine, and m-aminophenol; polyphenols such as polyvinylphenol, polyvinylphenol bromide, phenol novolac, and alkylphenol novolac; organic phosphines such as tributylphosphine, triphenylphosphine, and tris(2-cyanoethyl)phosphine; phosphonium salts such as tributyl(2,5-dihydroxyphenyl)phosphonium bromide and cetyltributylammonium chloride; quaternary ammonium salts such as benzyltrimethylammonium chloride and phenyltributylammonium chloride; polyanhydrides; photo cationic polymerization catalysts such as diphenyliodonium tetrafluoroborate, triphenylsulfonium hexafluoroantimonate, and 2,4,6-triphenylthiopyrylium hexafluorophosphate; styrene-maleic anhydride resins; equimolar reactants of phenyl isocyanate and dimethylamine, organic polyisocyanates such as toluene diisocyanate and isophorone diisocyanate with dimethylamine, and metal catalysts and other conventionally known curing accelerators. Among the above, from the viewpoints of low surface roughness and simultaneously exhibiting high-dimensional plating adhesion and heat resistance, imidazoles and imidazole derivatives are preferred.

[0081] The curing accelerator is not essential, but particularly when it is desired to promote the curing reaction, it is preferably used in the range of 0.1 to 2.0% by mass relative to the total amount of (A) the epoxy resin and (B) the polyarylate compound having a bisphenol structure and an ester group. One kind of curing accelerator or a combination of two or more kinds can be used.

[0082] [(D) Solvent]

[0083] The resin layer constituting the laminate of the present invention contains a (D) solvent. Together with (A) an epoxy resin, (B) a polyarylate compound having a bisphenol structure and an ester group, and an inorganic filler in a specified ratio, the (D) solvent is contained, so that it becomes easy to form a resin layer with a weight loss rate change of 3.0 mass% or less. The (D) solvent makes it easy to adjust the weight loss rate as described above, but also has the function of adjusting the viscosity for preparing a curable resin composition for forming a resin layer and for coating the curable resin composition on the first film. There is no particular limitation on the solvent, and examples thereof include ketones, aromatic hydrocarbons, glycol ethers, glycol ether acetates, esters, alcohols, aliphatic hydrocarbons, petroleum-based solvents, etc. More specifically, in addition to ketones such as methyl ethyl ketone, cyclohexanone, methyl butyl ketone, and methyl isobutyl ketone; aromatic hydrocarbons such as toluene, xylene, and tetramethylbenzene; glycol ethers such as cellosolve, methyl cellosolve, butyl cellosolve, carbitol, methyl carbitol, butyl carbitol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, propylene glycol monomethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol diethyl ether, and triethylene glycol monoethyl ether; esters such as ethyl acetate, butyl acetate, isobutyl acetate, ethylene glycol monoethyl ether acetate, dipropylene glycol methyl ether acetate, propylene glycol methyl ether acetate, propylene glycol ethyl ether acetate, and propylene glycol butyl ether acetate; alcohols such as ethanol, propanol, 2-methoxypropanol, n-butanol, isobutanol, isopentanol, ethylene glycol, and propylene glycol; aliphatic hydrocarbons such as octane and decane; petroleum-based solvents such as petroleum ether, petroleum naphtha, hydrogenated petroleum naphtha, and solvent naphtha, N,N-dimethylformamide (DMF), tetrachloroethylene, turpentine, etc. can also be cited. In addition, organic solvents such as Swasol 1000, Swasol 1500 manufactured by Maruzen Petrochemical Co., Ltd., Solvent #100, Solvent #150 manufactured by Sankyo Chemical Co., Ltd., Shellsol A100, Shellsol A150 manufactured by Shell Chemicals Japan Limited, IPSOL 100, IPSOL 150 manufactured by Idemitsu Kosan Co., Ltd. can also be used. These (D) solvents can be used alone or in combination of two or more.

[0084] The content of the (D) solvent in the resin layer is not particularly limited and can be in the range of 0.1 to 10.0 mass%.

[0085] [Other components]

[0086] In the resin layer constituting the laminate structure of the present invention, in addition to the above components, thermosetting components such as oxetane compounds and episulfide resins, organic fillers such as silica powder, fluorine powder, and nylon powder, coloring agents such as phthalocyanine blue, phthalocyanine green, iodine green, bisazo yellow, crystal violet, titanium oxide, carbon black, naphthol black, thickeners such as asbestos, Orben, Benton, and fine silica powder, defoamers and / or leveling agents such as silicone-based, fluorine-based, and polymer-based, and adhesion imparting agents such as thiazole-based and triazole-based and silane coupling agents, and other known additives can be contained.

[0087] <Manufacturing Method of Laminate Structure>

[0088] The laminate structure of the present invention can be manufactured as follows: Using a comma coater, knife coater, lip coater, bar coater, extrusion coater, reverse coater, transfer roll coater, gravure coater, spray coater, etc., a curable resin composition containing (A) an epoxy resin, (B) a polyarylate compound having a bisphenol structure and an ester group, a specified amount of (C) an inorganic filler, and (D) a solvent as essential components is coated on one surface of the first film with a uniform thickness to form a coating film. Usually, it is dried at a temperature of 60 to 180°C for 1 to 30 minutes to form a resin layer, and thus it can be manufactured. The thickness of the resin layer is usually 1 to 200 μm, preferably 10 to 150 μm.

[0089] As the first film, metal foils (such as copper foils, etc.), carrier films, etc. can be mentioned. The carrier film is not particularly limited. For example, polyester films such as polyethylene terephthalate and polyethylene naphthalate, polyimide films, polyamideimide films, polyethylene films, polytetrafluoroethylene films, polypropylene films, polystyrene films, etc. can be used. In addition, from the viewpoint of improving mechanical strength, the films as described above can be films stretched in the uniaxial or biaxial direction.

[0090] The surface of the first film on the resin layer side is preferably subjected to a release treatment. The release treatment can be carried out by coating a release agent on the surface of the first film to form a release layer. As the release agent, known silicone resins and non-silicone resins can be used, but in the present invention, non-silicone resins are preferably used. By combining a non-silicone resin with a polyarylate compound (B) having a bisphenol structure and an ester group, it is possible to suppress the occurrence of pinholes and shrinkage when coating a curable resin composition on the surface (resin layer side) of the first film. It should be noted that the non-silicone resin does not contain waxes. Conventionally, since the peelability of the first film using a silicone resin as a release agent is excellent, it is preferably used. However, when coating a curable resin composition containing a polyarylate compound (B) having a bisphenol structure and an ester group on the first film subjected to a release treatment with a silicone resin, pinholes and shrinkage are likely to occur. In contrast, in the first film subjected to a release treatment with a non-silicone resin, the occurrence of pinholes and shrinkage when coating a curable resin composition containing a polyarylate compound (B) having a bisphenol structure and an ester group can be suppressed. In addition, when using a silicone resin as a release agent, the polyarylate compound (B) having a bisphenol structure and an ester group absorbs the silicone resin, and as a result, there is a concern that the adhesion between the cured product and the plating layer may be reduced. However, in the first film subjected to a release treatment with a non-silicone resin, the adhesion between the cured product and the plating layer can be improved.

[0091] For the laminated structure, for the purpose of preventing dust from adhering to the surface of the resin layer, etc., a second film can be provided on the surface of the resin layer so as to be peelable. As the second film, the same film as the first film can be used. For example, a polyester film, a polyethylene film, a polypropylene film, etc. can be used. It should be noted that peelable means that when the second film is peeled from the resin layer, the adhesion between the resin layer and the second film is less than the adhesion between the resin layer and the first film. For example, the surface of the second film can be subjected to a release treatment.

[0092] The laminated structure of the present invention can be suitably used as a resin-coated copper foil (RCC: Resin-Coated-Copper) for a modified / semi-additive process (MSAP) and a laminated film for a semi-additive process (SAP).

[0093] <Cured Product and Electronic Component>

[0094] The cured product of the present invention is obtained by curing the resin layer of the laminated structure. For example, by heating the resin layer of the laminated structure at a temperature of 150 to 250 °C for 30 to 90 minutes to thermally cure the resin component, a cured product of the resin layer can be obtained.

[0095] As a substrate for laminating the resin layer of the laminated structure, in addition to printed wiring boards and flexible printed wiring boards in which circuits are formed in advance of copper or the like, there may be mentioned: copper-clad laminates of all grades (such as FR-4), metal substrates, polyimide films, polyethylene terephthalate films, polyethylene naphthalate (PEN) films, glass substrates, ceramic substrates, wafer boards, etc., and the copper-clad laminates use materials such as phenolic paper, paper epoxy, glass cloth epoxy, glass polyimide, glass cloth / non-woven fabric epoxy, glass cloth / paper epoxy, synthetic fiber epoxy, high-frequency circuit copper-clad laminates using fluororesin / polyethylene / polyphenylene oxide, polyphenylene oxide / cyanate ester, etc.

[0096] When laminating the resin layer of the laminated structure on a substrate, it is preferably carried out under pressure and heating using a vacuum laminator or the like. By using such a vacuum laminator, even if there are irregularities on the surface of the circuit board, the resin layer adheres closely to the circuit board, so that no air bubbles are mixed in, and in addition, the filling property of the concave portions on the substrate surface is also improved. After laminating the resin layer of the laminated structure on the substrate, it is heated at a temperature of 150 to 250 °C for 30 to 90 minutes to thermally cure the resin component, and a cured product can be obtained.

[0097] According to the laminated structure of the present invention, a cured product having a surface roughness lower than 0.30 μm, further lower than 0.20 μm, a peel strength from the plating layer of 3.0 N / cm or more, further 3.5 N / cm or more, and a glass transition temperature of 180 °C or more, further 190 °C or more can be obtained.

[0098] The cured product obtained from the laminated structure of the present invention can be used as an insulating layer of an electronic component and can be suitably used as an interlayer insulating film of a multilayer printed circuit board. It should be noted that the cured product can also be used as a passivation film of a semiconductor, a protective film of a semiconductor element, an interlayer insulating film of a semiconductor, a solder resist layer of a printed circuit board, and a cover layer of a flexible printed circuit board.

[0099] As electronic components, in addition to printed circuit boards and semiconductors, there are also passive components such as inductors, etc. In addition, as electronic components for high-frequency applications, for example, there may be mentioned: millimeter-wave radars for autonomous driving, substrates for millimeter-wave sensors, mobile motherboards for high-speed communication, SLP (Substrate-Like PCB) formed by the modified / semi-additive process (MSAP) method, application processors (APs) for mobile and personal computers, high-multilayer substrates for base station servers or routers, substrates for antennas, etc.

[0100] Examples

[0101] Next, examples are given to illustrate the present invention in more detail, but the present invention is not limited to these examples. It should be noted that unless otherwise specified, the following "parts" and "%" are all based on mass.

[0102] <Preparation of curable resin composition>

[0103] After compounding each component described in Table 1 below and stirring well, it was kneaded and mixed with a three-roll mill to obtain each curable resin composition described in the same table. It should be noted that each value in the table represents parts by mass or mass% in terms of solid content.

[0104] It should be noted that each component *1 to *9 in Table 1 below is as described below.

[0105] *1: Bisphenol A-bisphenol F type mixed epoxy resin (solid content 100% by mass) manufactured by NIPPON STEEL Chemical&Material Co., Ltd., epoxy equivalent (equivalent derived from the content of epoxy groups) 165 g / eq.

[0106] *2: Biphenol novolac type epoxy resin (solid content 100% by mass) manufactured by Nippon Kayaku Co., Ltd., epoxy equivalent (equivalent derived from the content of epoxy groups) 290 g / eq.

[0107] *3: Unifiner (registered trademark) W-575 manufactured by UNITIKA LTD. (solid content 100% by mass), functional group equivalent (equivalent derived from the content of ester groups and phenolic hydroxyl groups) 220 g / eq., number average molecular weight 3200, capped type with phenolic hydroxyl end

[0108] *4: Unifiner (registered trademark) V-575 manufactured by UNITIKA LTD. (solid content 100% by mass), functional group equivalent (equivalent derived from the content of ester groups and phenolic hydroxyl groups) 210 g / eq., number average molecular weight 3300, phenolic hydroxyl end type

[0109] *5: Active ester compound having a dicyclopentadiene skeleton manufactured by DIC Corporation (solid content 65% by mass), ester equivalent 223 g / eq.

[0110] *6: Active ester compound having a naphthalene skeleton manufactured by DIC Corporation (solid content 62% by mass), ester equivalent 230 g / eq.

[0111] *7: Spherical silica treated with phenylaminosilane manufactured by Admatechs Co., Ltd. (solid content 100% by mass), average particle size (D50): 0.5 μm

[0112] *8: Phenoxy resin containing a bisphenol skeleton (solid content: 30% by mass) manufactured by Mitsubishi Chemical Corporation, epoxy equivalent: 13,000 g / eq.

[0113] *9: 2-Ethyl-4-methylimidazole manufactured by Shikoku Kasei Kogyo Co., Ltd.

[0114] <Fabrication of the laminated structure>

[0115] Using a film applicator, apply each of the above-obtained curable resin compositions onto the release-treated surface of a polyethylene terephthalate film (manufactured by Toyobo Co., Ltd., product number: TN-200, a film having a release layer of non-silicone resin on one side) to form a coating film. Thereafter, dry the coating film in a hot air circulation drying oven under the drying conditions shown in Table 2 to form a resin layer with a thickness of 40 μm, and fabricate a laminated structure.

[0116] <Measurement of weight loss rate>

[0117] Heat a copper foil with a thickness of 18 μm and cut into 150 mm × 90 mm (manufactured by Furukawa Electric Co., Ltd., F2-WS) using a hot plate at 80°C, and bond the resin layer of each of the above laminated structures to the shiny surface of the copper foil within 10 seconds. Thereafter, immediately return to room temperature, and peel off the polyethylene terephthalate film.

[0118] After measuring the mass of the obtained copper foil with a resin layer, measure the mass of the copper foil with a resin layer after heating the copper foil with a resin layer at 100°C under atmospheric pressure for 20 minutes and then naturally cooling at room temperature for 20 minutes.

[0119] The weight loss rate is calculated according to the following formula. The calculation results are shown in Table 2.

[0120] 100 × (mass of the resin layer before heating - mass of the resin layer after heating) / mass of the resin layer before heating

[0121] <Evaluation of the surface roughness of the cured product>

[0122] Using an intermittent vacuum pressure laminator (MVLP-500, manufactured by Meiki Seisakusho Co., Ltd.), laminate the resin layers of the laminated structures of the examples and comparative examples on both sides of a copper-clad laminate (CCL-HL832NX, manufactured by Mitsubishi Gas Chemical Company, Inc., copper thickness: 0.4 mm). The lamination is carried out as follows: reduce the pressure for 30 seconds to make the air pressure 13 hPa or less, and then apply pressure at 110°C and 0.5 MPa for 30 seconds.

[0123] Next, it was heated at 150°C for 30 minutes in a hot air circulation drying furnace to cure the resin layer, and then the polyethylene terephthalate film was peeled off from the surface of the cured product to obtain a laminate having cured products formed on both sides of the copper-clad laminate.

[0124] Then, the obtained laminate was immersed in a commercially available wet high-manganese acid desmear agent (manufactured by Atotech Japan K.K., Swelling Dip Securiganth P) at 60°C for 10 minutes (swelling treatment), and then immersed in potassium permanganate (manufactured by Atotech Japan K.K., CONCENTRATE COMPACT CP) at 80°C for 20 minutes to perform roughening treatment. Next, it was immersed in a neutralizing solution (manufactured by Atotech Japan K.K., Reduction Securiganth P500) at 40°C for 5 minutes (reduction treatment), and then dried at 100°C for 30 minutes in a hot air circulation drying furnace.

[0125] In order to evaluate the surface state of the cured product after the roughening treatment, the surface roughness Ra was measured using a laser microscope (VK-8500, manufactured by KEYENCE CORPORATION, magnification: 100 times). The evaluation of the surface roughness was carried out according to the following criteria.

[0126] ◎: Less than 0.20 μm

[0127] 〇: 0.20 μm or more and less than 0.30 μm

[0128] △: 0.30 μm or more and less than 0.35 μm

[0129] ×: 0.35 μm or more

[0130] The evaluation results are shown in Table 2 below.

[0131] <Evaluation of plating adhesion>

[0132] A test substrate for evaluating plating adhesion was produced according to the following procedure.

[0133] (1) Both sides of a copper-clad laminate (CCL-HL832NX, manufactured by Mitsubishi Gas Chemical Co., Ltd., copper thickness: 0.4 mm, length: 150 mm, width: 100 mm) were immersed in CZ8100 manufactured by MEC Co., Ltd. to perform roughening treatment of the copper surface (etching amount: about 1 μm).

[0134] (2) Next, the resin layers of the laminated structures of the examples and comparative examples were laminated on both sides of the copper-clad laminate subjected to the roughening treatment described above using an intermittent vacuum pressurizing laminator (MVLP-500, manufactured by Meiki Seisakusho Co., Ltd.). The lamination was performed by reducing the pressure for 30 seconds to a pressure of 13 hPa or less, and then pressurizing at 110° C. and a pressure of 0.5 MPa for 30 seconds.

[0135] (3) Then, the resin layer was cured by heating at 150° C. for 30 minutes in a hot air circulation drying oven, and the polyethylene terephthalate film was peeled off from the surface of the cured product to obtain a laminate having cured products formed on both surfaces of the copper-clad laminate.

[0136] (4) The obtained laminate was immersed in a commercially available wet permanganate desmear (Swelling Dip Securiganth P manufactured by Atotech Japan K.K.) at 60°C for 10 minutes (swelling treatment), then immersed in potassium permanganate (CONCENTRATE COMPACT CP manufactured by Atotech Japan KK) at 80°C for 20 minutes (roughening treatment), then immersed in a neutralizing solution (Reduction Securiganth P500 manufactured by Atotech Japan KK) at 40°C for 5 minutes (reduction treatment), and then dried in a hot air circulation drying oven at 100°C for 30 minutes.

[0137] (5) Then, chemical copper plating was performed on the roughened solid (Cleaner 40°C for 5 minutes, Predip 25°C for 2 minutes, Activator 40°C for 5 minutes, Reducer 35°C for 3 minutes, Accelerator 25°C for 1 minute, THRU-CUP Ver2, manufactured by Uemura Industries, Ltd., 36°C for 20 minutes). The solid formed with the chemical copper plating layer was heated at 150°C for 30 minutes in a hot air circulation drying furnace, and then copper sulfate electroplating was performed to form an electrolytic copper plating layer with a thickness of 25±5μm on the solid, and then heated at 190-200°C for 60 minutes to prepare a test substrate.

[0138] In the copper-plated layer of the test substrate obtained as described above, a cut of 10 mm in width and 60 mm in length was introduced to remove the copper-plated layers at both ends in the width direction. One end of the remaining copper-plated layer in the length direction was peeled off, clamped with a gripper, and a table-type tensile tester (manufactured by Shimadzu Corporation, AG-X) was used to measure the peel strength (N / cm) when the copper-plated layer was peeled off at an angle of 90 degrees and at a speed of 50 mm / min for a length of 35 mm. The evaluation of the adhesion of the coating was carried out according to the following benchmarks.

[0139] ◎: Above 3.5 N / cm

[0140] 〇: Above 3.0 N / cm and below 3.5 N / cm

[0141] △: Above 2.5 N / cm and below 3.0 N / cm

[0142] ×: Below 2.5 N / cm

[0143] The evaluation results are shown in Table 2 below.

[0144] <Evaluation of heat resistance>

[0145] Using a film applicator, each curable resin composition was coated on the glossy surface of a copper foil (F2-WS manufactured by Furukawa Electric Co., Ltd., thickness 18 μm), dried in a hot air circulation drying oven at 90°C for 10 minutes, and then cured at 200°C for 60 minutes to obtain a cured product. After that, the copper foil was peeled off from the surface of the cured product to produce a film-like cured product with a thickness of about 40 μm.

[0146] The cured product obtained as described above was cut into a measurement size (size of 3 mm × 10 mm), and the glass transition temperature (Tg) was measured using a TMA Q400EM manufactured by TA Instruments. The glass transition temperature was set as follows: After heating from room temperature to 300°C at a heating rate of 10°C / minute, it was cooled to room temperature, and heating measurement was repeated 2 times under the same conditions again. The temperature (Tg) was the intersection temperature of 2 tangents with different linear thermal expansion coefficients in the second time. The evaluation of the heat resistance of the cured product was carried out according to the following criteria.

[0147] ◎: Tg is 190°C or higher

[0148] 〇: Tg is above 180°C and below 190°C

[0149] ×: Tg is below 180°C

[0150] The evaluation results are shown in Table 2 below.

[0151] [Table 1]

[0152]

[0153] [Table 2]

[0154]

[0155] It is also clearly understood from Tables 1 and 2 that in a laminated structure in which a resin layer is formed of a curable resin composition containing (A) an epoxy resin, (B) a polyarylate compound having a bisphenol structure and an ester group, a specified amount of (C) an inorganic filler, and (D) a solvent, for the laminated structures (Examples 1 to 7) having a weight loss rate of 3.0% by mass or less after heating the resin layer under specified conditions, a cured product having a low surface roughness, excellent plating adhesion, and excellent heat resistance is obtained.

[0156] In contrast, in a laminated structure in which a resin layer is formed of a curable resin composition containing (A) an epoxy resin, (B) a polyarylate compound having a bisphenol structure and an ester group, a specified amount of (C) an inorganic filler, and (D) a solvent, for the laminated structure (Comparative Example 1) having a weight loss rate exceeding 3.0% by mass after heating the resin layer under specified conditions, although the obtained cured product has excellent heat resistance, the surface roughness and plating adhesion are insufficient.

[0157] In addition, for the laminated structures (Comparative Examples 2 and 3) in which even if the weight loss rate after heating the resin layer under specified conditions is 3.0% by mass or less and the resin layer does not contain (B) a polyarylate compound having a bisphenol structure and an ester group, although the surface of the obtained cured product has a low roughness, the plating adhesion and heat resistance are insufficient.

[0158] In addition, for the laminated structure (Comparative Example 4) in which even if the weight loss rate after heating the resin layer under specified conditions is 3.0% by mass or less and the content of (C) the inorganic filler contained in the resin layer is less than 38% by mass based on the solid content, the obtained cured product has a surface with a low roughness and excellent heat resistance, but the plating adhesion is insufficient.

[0159] Moreover, for the laminated structure (Comparative Example 5) in which even if the weight loss rate after heating the resin layer under specified conditions is 3.0% by mass or less and the content of (C) the inorganic filler contained in the resin layer exceeds 82% by mass based on the solid content, although the obtained cured product also has excellent heat resistance, the surface roughness and plating adhesion are insufficient.

[0160] Furthermore, for the laminated structure (Comparative Example 6) in which the resin layer does not contain (B) a polyarylate compound having a bisphenol structure and an ester group and the content of (C) the inorganic filler is less than 38% by mass based on the solid content, although the obtained cured product has a surface with a low roughness, the plating adhesion and heat resistance are insufficient.

Claims

1. A stacked structure, characterized in that, Comprising: a first film, and a resin layer provided on the first film, The resin layer contains: (A) an epoxy resin, (B) a polyarylate compound having a bisphenol structure and an ester group, (C) an inorganic filler, and (D) a solvent, The resin layer contains 38 to 82% by mass of the (C) inorganic filler based on the solid content, The weight loss rate of the resin layer after heating the resin layer at 100°C under atmospheric pressure for 20 minutes is 3.0% by mass or less.

2. The laminated structure according to claim 1, wherein, The weight loss rate of the resin layer after heating the resin layer at 100°C for 20 minutes is 2.0% by mass or less.

3. The laminated structure according to claim 1, wherein, The resin layer substantially does not contain a photoinitiator and a photopolymerizable compound.

4. A method for manufacturing a laminated structure, which is a method for manufacturing the laminated structure according to any one of claims 1 to 3, and the manufacturing method includes the following steps: Preparing a curable resin composition, the curable resin composition contains (A) an epoxy resin, (B) a polyarylate compound having a bisphenol structure and an ester group, (C) an inorganic filler, and (D) a solvent, and the resin layer contains 38 to 82% by mass of the (C) inorganic filler based on the solid content; Coating the curable resin composition on one surface of the first film to form a coating film; Drying the coating film at a temperature of 60 to 180°C for 1 to 30 minutes to form a resin layer.

5. A cured product, which is a cured product of the resin layer of the laminated structure according to any one of claims 1 to 3.

6. An electronic component, which has the cured product according to claim 5.

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