Manufacturing method of printed wiring board

Abstract

The objective of this invention is to provide a method for manufacturing a printed circuit board (PCB) that can suppress poor peeling between the insulating layer and the support while simultaneously manufacturing the PCB. The solution of this invention is a method for manufacturing a PCB, which sequentially includes: (I) a step of laminating a resin sheet onto an inner layer substrate in a manner that bonds a resin composition layer to the inner layer substrate, wherein the resin sheet comprises: a support having a release layer, and a resin composition layer formed on the release layer of the support; (II) a step of thermosetting the resin composition layer in a nitrogen atmosphere; and (III) a step of peeling off the support, wherein the release layer comprises a (meth)acrylic resin, the resin composition layer comprises a resin composition comprising an imidazole compound, and the thermosetting of the resin composition layer sequentially includes: subjecting the resin composition layer to a heat treatment held at a temperature T1, and subjecting the resin composition layer to a heat treatment held at a temperature T2 higher than T1.

Description

Technical Field

[0001] This invention relates to a method for manufacturing a printed wiring board. Prior Technology

[0002] Printed wiring boards (PCBs) are widely used in various electronic instruments. For PCBs, miniaturization and high functionality in electronic instruments necessitate finer and higher-density circuit wiring. One known method for manufacturing PCBs is a buildup method that alternately stacks insulating and conductive layers on an inner substrate. The insulating layer is formed, for example, by forming a resin composition layer containing a resin composition on the inner substrate and then thermally curing the resin composition layer (Patent Documents 1 and 2). [Previous Technical Documents] [Patent Literature]

[0003] [Patent Document 1]: Japanese Patent Application Publication No. 2002-167427 [Patent Document 2]: Japanese Patent Application Publication No. 2013-75948. Summary of the Invention

[0004] [The problem that the invention aims to solve]

[0005] One method for forming the insulating layer of a printed circuit board is using a resin sheet. In this method, a resin sheet comprising a support and a resin composition layer is prepared, an inner substrate and the resin composition layer are laminated, and then the resin composition layer is thermo-cured to obtain the insulating layer. In this method, sometimes the thermo-curing of the resin composition layer is performed while it is in contact with the support, and the support is peeled off after this thermo-curing. For example, sometimes, to suppress damage to the insulating layer when forming vias using laser irradiation, the resin composition layer is thermo-cured to form an insulating layer, and then the support is peeled off after a via is formed in the insulating layer.

[0006] Furthermore, the thermosetting of the resin composition layer is sometimes carried out in a nitrogen atmosphere. For example, if the thermosetting of the resin composition layer is carried out in an air atmosphere, the components contained in the resin composition layer may sometimes deteriorate due to oxidation. In contrast, when the thermosetting of the resin composition layer is carried out in a nitrogen atmosphere, the above-mentioned deterioration caused by oxidation can be suppressed, and thus an insulating layer with excellent dielectric and mechanical properties can be formed.

[0007] However, when the resin composition layer is thermo-cured in a nitrogen atmosphere without peeling off the support, poor peeling sometimes occurs between the insulating layer obtained by curing the resin composition layer and the support. The inventors' research shows that the aforementioned poor peeling occurs when the resin composition layer contains an imidazole compound and the support has a release layer containing a (meth)acrylic resin.

[0008] The present invention was created in view of the above-mentioned problems, and its object is to provide a method for manufacturing a printed wiring board, which can suppress poor peeling between the insulation layer and the support body and simultaneously manufacture a printed wiring board. [Methods for solving problems]

[0009] The inventors have conducted diligent research to solve the aforementioned problems. As a result, the inventors discovered that the thermosetting of the resin composition layer, which involves changing the curing temperature and curing the resin composition layer in stages, can solve the aforementioned problems, thus completing the present invention. That is, the present invention includes the following solutions.

[0010] [1]. A method for manufacturing a printed wiring board, the method comprising, in sequence: (I) A step of laminating a resin sheet onto an inner substrate in such a manner as bonding a resin composition layer to an inner substrate, wherein the resin sheet comprises: a support having a release layer, and a resin composition layer formed on the release layer of the support; (II) The step of heat-curing the resin composition layer in a nitrogen atmosphere; and (III) Steps for peeling off the support body, The release layer contains (meth)acrylic resin ((meth)acrylic resin). The resin composition layer comprises a resin composition, wherein the resin composition comprises an imidazole compound. The thermosetting of the resin composition layer includes, in sequence: performing a heat treatment on the resin composition layer at a temperature T1, and performing a heat treatment on the resin composition layer at a temperature T2 higher than T1. [2]. The method for manufacturing a printed wiring board as described in [1], wherein the resin composition comprises a thermosetting resin. [3]. The method for manufacturing a printed wiring board as described in [2], wherein the thermosetting resin comprises one or more selected from epoxy resin, phenolic resin, reactive ester resin, carbodiimide resin, acid anhydride resin, amine resin, benzoxazine resin, cyanate ester resin and thiol resin. [4]. A method for manufacturing a printed wiring board as described in any one of [1] to [3], wherein the temperature T2 is 150°C or higher. [5]. A method for manufacturing a printed wiring board as described in any one of [1] to [4], wherein the temperature difference T2-T1 between temperature T2 and temperature T1 is 20°C or more. [6]. A method for manufacturing a printed wiring board as described in any one of [1] to [5], wherein the temperature T1 is 50°C or higher. [7]. A method for manufacturing a printed wiring board as described in any one of [1] to [6], wherein step (II) comprises: heating the resin composition layer to a temperature T2 at a heating rate of 0.5°C / min or more and 30°C / min or less. [The effects of the invention]

[0011] According to the present invention, it is possible to manufacture printed wiring boards while suppressing poor peeling between the insulation layer and the support. Implementation

[0012] [Optimal Form of Invention Implementation]

[0013] Hereinafter, embodiments and examples of the present invention will be described. However, the present invention is not limited to the embodiments and examples shown below, and can be implemented by any modifications without departing from the scope of the claims and their equivalents.

[0014] In the following description, "strip" unless otherwise stated refers to a film or sheet having a length that is 10 times or more than its width. Preferably, the length is 20 times or more than the width, and specifically, it can be a length suitable for winding into a roll for storage or handling. There is no particular upper limit to the length; for example, it can be less than 100,000 times the width.

[0015] [Overview of the manufacturing method of printed circuit boards] One embodiment of the present invention relates to a method for manufacturing a printed wiring board using a resin sheet. The resin sheet comprises: a support having a release layer, and a resin composition layer formed on the release layer of the support. Specifically, the method for manufacturing a printed wiring board according to this embodiment includes, in sequence: (I) The step of laminating a resin sheet onto an inner substrate in a manner that bonds a resin composition layer to the inner substrate. (II) The steps of thermosetting the resin composition layer in a nitrogen atmosphere, and (III) Step of peeling off the support. In this method, an insulating layer is formed by curing the resin composition layer, thus enabling the manufacture of a printed wiring board having the insulating layer.

[0016] The release layer of the support comprises a (meth)acrylic resin. Additionally, the resin composition layer comprises a resin composition containing an imidazole compound. Furthermore, the thermosetting of the resin composition layer in step (II) comprises subjecting the resin composition layer to a heat treatment held at temperature T1, and then subjecting it to a heat treatment held at a temperature T2 higher than temperature T1.

[0017] Conventionally, when a release layer containing (meth)acrylic resin and a resin composition containing imidazole compounds are combined and then heat-treated in a nitrogen atmosphere, poor peeling occurs between the insulation layer and the support. Specifically, when attempting to peel off the support, adhesion (fixation) occurs between the insulation layer and the support, and either the insulation layer or the support may break. In contrast, by controlling the heat curing conditions in step (II) as in this embodiment, poor peeling between the insulation layer and the support can be suppressed.

[0018] The inventors speculate that the aforementioned poor peeling structure (mechanism) can be suppressed as described below. However, the scope of the present invention is not limited to the structure described below.

[0019] Assuming that the resin composition layer is thermocured in air, the catalytic activity of imidazole compounds can be suppressed by the oxygen and carbon dioxide contained in the air. However, the catalytic activity of imidazole compounds is not suppressed when thermocure is performed in a nitrogen atmosphere. Therefore, conventionally, due to the catalytic activity of imidazole compounds, a reaction occurs between the (meth)acrylic resin contained in the release layer and one or more components contained in the resin composition, resulting in the release layer sometimes sticking to the resin composition layer. According to the inventors' research, it is speculated that the (meth)acrylic resin in the release layer reacts with thermosetting resins that may be contained in the resin composition, particularly epoxy resins, phenolic resins, and reactive ester resins. The inventors speculate that this adhesion is one of the causes of previous poor peeling.

[0020] In contrast, in the manufacturing method of the printed wiring board according to this embodiment, the resin composition layer is hardened in stages by holding at a temperature T1 and then holding at a temperature T2 higher than T1. During this staged hardening, the reaction between the components contained in the resin composition layer and each other occurs preferentially compared to the reaction between the (meth)acrylic resin contained in the release layer and the components contained in the resin composition. For example, if the reaction between the components contained in the resin composition layer occurs at temperature T1, the number of reactive components in the resin composition layer decreases. Therefore, at temperature T2, the reaction between the (meth)acrylic resin contained in the release layer and the components contained in the resin composition layer proceeds less. Therefore, adhesion between the release layer and the resin composition layer can be suppressed, thereby suppressing poor peeling.

[0021] [Resin Sheets] One embodiment of the present invention relates to a method for manufacturing a printed wiring board, wherein the resin sheet used comprises: a support having a release layer, and a resin composition layer disposed on the release layer of the support.

[0022] -Support Body- The support typically has a support substrate on which a release layer is provided. Examples of support substrates include thermoplastic resin films, metal foils, and release paper, with thermoplastic resin films and metal foils being preferred.

[0023] When using a thermoplastic resin film as a support substrate, examples of thermoplastic resins include polyesters such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), acrylic polymers such as polycarbonate (PC) and polymethyl methacrylate (PMMA), cyclic polyolefins, triacetin cellulose (TAC), polyether sulfide (PES), polyether ketone, and polyimide. Among these, polyethylene terephthalate and polyethylene naphthalate are preferred, and inexpensive polyethylene terephthalate is particularly preferred.

[0024] When using metal foil as a support substrate, examples of metal foils include copper foil and aluminum foil, with copper foil being preferred. As copper foil, foil formed from copper as a single metal can be used, or foil formed from an alloy of copper with other metals (e.g., tin, chromium, silver, magnesium, nickel, zirconium, silicon, titanium, etc.) can be used.

[0025] For the supporting substrate, surface treatments such as matte treatment, corona treatment, and antistatic treatment can be applied to the surface of the release layer side.

[0026] The thickness of the support substrate is not particularly limited, but it is preferably in the range of 5μm to 75μm, and more preferably in the range of 10μm to 60μm.

[0027] The release layer comprises (meth)acrylic resin. In this specification, "(meth)acrylic resin" includes (meth)acrylic compounds and their polymers. Additionally, "(meth)acrylic compounds" includes acrylic compounds containing an acrylonitrile group, methacrylic compounds containing a methacrylic group, and combinations thereof.

[0028] Generally, a release layer is formed using a release agent. Release agents typically contain a release compound that imparts release properties, and may further contain any resin other than the release compound, depending on the need. Therefore, in one example, a release layer formed using a release agent contains a release compound, and may further contain any resin, depending on the need. Alternatively, in another example, a release layer formed using a release agent can be formed by combining some or all of the components contained in the release agent through reactions such as polymerization and crosslinking, after which the release agent hardens. Therefore, in this example, the release layer may contain the release compound and any resin contained in the release agent, as well as their reaction products (e.g., polymers). (Meth)acrylic resins may be contained as a release compound, as any resin, or as their reaction products.

[0029] Release compounds are compounds that can reduce the surface free energy of the release layer or reduce the static friction coefficient of the release layer. Therefore, (meth)acrylic resins as release compounds can be (meth)acrylic resins that can perform the above-mentioned functions.

[0030] Examples of (meth)acrylic resins that serve as mold release compounds include, for example, (meth)acrylic resins containing long-chain alkyl groups and (meth)acrylic resins containing fluorine atoms.

[0031] Long-chain alkyl groups typically have 12 or more carbon atoms, preferably 16 or more. (Meth)acrylic resins containing such long carbon chains exhibit high hydrophobicity and therefore excellent mold release properties. The upper limit for the number of carbon atoms in a long-chain alkyl group can be, for example, 25 or less. Examples of (meth)acrylic resins containing long-chain alkyl groups include, for example, long-chain acrylic acrylates such as tetradecyl acrylate and octadecyl acrylate; long-chain acrylic methacrylates such as tetradecyl methacrylate and octadecyl methacrylate; and polymers thereof.

[0032] Examples of (meth)acrylic resins containing fluorine atoms include fluoroalkyl acrylates such as trifluoroethyl acrylate; fluoroaryl acrylates such as pentafluorophenyl acrylate; fluoroalkyl methacrylates such as trifluoroethyl methacrylate; fluoroaryl methacrylates such as pentafluorophenyl methacrylate; and polymers thereof.

[0033] Examples of (meth)acrylic resins that can be classified as any type of resin include acrylic acid, methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, n-hexyl acrylate, lauryl acrylate, 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, hydroxypropyl acrylate, acrylamide, N-hydroxymethylacrylamide, diacetone acrylamide, and other acrylic acid compounds; methacrylic acid, methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-hexyl methacrylate, lauryl methacrylate, 2-hydroxyethyl methacrylate, hydroxypropyl methacrylate, and other methacrylic acid compounds; and polymers thereof.

[0034] (Meth)acrylic resins can be used alone or in combination of two or more.

[0035] The amount of (meth)acrylic resin in the release layer is preferably 30% by mass or more, more preferably 50% by mass or more, further preferably 70% by mass or more, particularly preferably 90% by mass or more, and typically less than 100% by mass, relative to 100% by mass of the release layer. Conventionally, when using a release layer containing (meth)acrylic resin, a problem of poor peeling between the insulating layer and the support has occurred. According to the manufacturing method described in this embodiment, this problem of poor peeling can be suppressed.

[0036] Furthermore, the amount of (meth)acrylic resin in the release agent used in the manufacture of the aforementioned release layer is preferably 30% by mass or more, more preferably 50% by mass or more, further preferably 70% by mass or more, particularly preferably 90% by mass or more, and typically less than 100% by mass, relative to 100% by mass of the non-volatile components of the release agent. Conventionally, when using a release agent containing (meth)acrylic resin to form a release layer, a problem of poor peeling between the insulating layer and the support occurs. According to the manufacturing method described in this embodiment, this problem of poor peeling can be suppressed.

[0037] The release layer may also be combined with the aforementioned (meth)acrylic resin to further include any components other than (meth)acrylic resin. Additionally, the release agent used to form this release layer may also be combined with the aforementioned (meth)acrylic resin to further include any components other than (meth)acrylic resin. Examples of any components other than (meth)acrylic resin include, for example, release compounds other than (meth)acrylic resin. Examples of release compounds other than (meth)acrylic resin include, for example, resins containing long-chain alkyl groups, olefin resins, fluorinated compounds, wax compounds, etc.

[0038] Examples of compounds containing long-chain alkyl groups include compounds other than (meth)acrylic resins. Specific examples of compounds containing long-chain alkyl groups include long-chain alkyl compounds manufactured by ASHIO Corporation, namely the "ASHIO RESIN" (registered trademark) series; long-chain alkyl compounds manufactured by LION SPECIALTY CHEMICALS Corporation, namely the "Peeloil" (registered trademark) series; and aqueous dispersions of long-chain alkyl compounds manufactured by Chukyo Oils & Fats Corporation, namely the "Resem" series.

[0039] Examples of olefin resins include propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-heptene, 1-octene, 1-nonene, 1-decene, 1-undecene, and 1-dodecene.

[0040] Examples of fluorinated compounds include compounds other than (meth)acrylic resins that contain fluorine atoms in their molecules. Specific examples of fluorinated compounds include compounds containing perfluoroalkyl groups, polymers of olefin compounds containing fluorine atoms, and aromatic fluorinated compounds such as fluorobenzenes.

[0041] Examples of wax compounds include natural waxes, synthetic waxes, and waxes composed of combinations thereof. Natural waxes include plant-based waxes, animal-based waxes, mineral-based waxes, and petroleum waxes. Examples of plant-based waxes include candelilla wax, carnauba wax, rice wax, wood wax, and jojoba oil. Examples of animal-based waxes include beeswax, lanolin, and whale wax. Examples of mineral-based waxes include lignite wax, ozocerite, and ceresin. Examples of petroleum waxes include paraffin wax, microcrystalline wax, and petrolatum. Examples of synthetic waxes include synthetic hydrocarbons, modified waxes, hydrogenated waxes, fatty acids, amides, amines, amides, esters, and ketones. Examples of synthetic hydrocarbons include Fischer-Tropsch wax (also known as Sasol Wax) and polyethylene wax. Furthermore, in the synthetic hydrocarbon, a low molecular weight substance (specifically, a viscosity-average molecular weight of 500 or more and 20,000 or less) may be included in polymers selected from polypropylene, ethylene / acrylic acid copolymers, polyethylene glycol, polypropylene glycol, block copolymers of polyethylene glycol and polypropylene glycol, and graft copolymers of polyethylene glycol and polypropylene glycol. Examples of modified waxes include, for example, lignite wax derivatives, paraffin wax derivatives, and microcrystalline wax derivatives. Here, "derivative" refers to a compound obtained through any of the following treatments: refining, oxidation, esterification, saponification, or a combination thereof. Examples of hydrogenated waxes include, for example, hydrogenated castor oil and hydrogenated castor oil derivatives.

[0042] Any release compound other than (meth)acrylic resins may be used alone or in combination of two or more.

[0043] The amount of the release compound in the release agent (the total amount of (meth)acrylic resins and other release compounds besides (meth)acrylic resins) relative to 100% by mass of the non-volatile components of the release agent is preferably 10% by mass or more, more preferably 15% by mass or more, particularly preferably 20% by mass or more, preferably 90% by mass or less, more preferably 60% by mass or less, and particularly preferably 40% by mass or less.

[0044] In addition, the amount of the release compound in the release layer (the total amount of (meth)acrylic resin and other release compounds besides (meth)acrylic resin) relative to 100% by mass of the release layer is preferably 10% by mass or more, more preferably 15% by mass or more, particularly preferably 20% by mass or more, preferably 90% by mass or less, more preferably 60% by mass or less, and particularly preferably 40% by mass or less.

[0045] Other examples of arbitrary components include any resin other than (meth)acrylic resins. Examples of arbitrary resins other than (meth)acrylic resins include epoxy resins, melamine resins, oxazoline compounds, carbodiimide compounds, polyester resins, and urethane resins. Any resin other than (meth)acrylic resins may be used alone or in combination of two or more.

[0046] The amount of any resin in the release agent (the total of (meth)acrylic resins and any resins other than (meth)acrylic resins) relative to 100% by mass of the non-volatile components of the release agent is preferably 10% by mass or more, more preferably 20% by mass or more, particularly preferably 40% by mass or more, preferably 90% by mass or less, more preferably 80% by mass or less, and particularly preferably 60% by mass or less.

[0047] In addition, the amount of any resin in the release layer (the total of (meth)acrylic resins and any resins other than (meth)acrylic resins) relative to 100% by mass of the release layer is preferably 10% by mass or more, more preferably 20% by mass or more, particularly preferably 40% by mass or more, preferably 90% by mass or less, more preferably 80% by mass or less, and particularly preferably 60% by mass or less.

[0048] Further examples of any component include additives such as lubricants, inorganic particles, organic particles, surfactants, antioxidants, and thermal initiators. These additives can be used alone or in combination of two or more. There are no particular limitations on the amount of additives; for example, it can be 0.01% by mass or more and 10% by mass or less relative to 100% by mass of the total amount of the release compound and any resin.

[0049] The thickness of the release layer is preferably above 50nm, more preferably above 70nm, better than below 400nm, better than below 200nm, and especially preferably below 130nm.

[0050] The support can be manufactured, for example, by applying a release agent to the surface of a support substrate. The release agent may also contain a solvent in combination with the aforementioned (meth)acrylic resin and any other non-volatile components. When the release agent contains a solvent, the support is preferably manufactured by drying after applying the release agent.

[0051] From the viewpoint of suppressing rapid evaporation of the solvent and forming a uniform release layer, an aqueous solvent is preferred. Examples of aqueous solvents include water; and mixtures of water with water-soluble organic solvents such as alcohols, ketones, and glycols. A single solvent or a combination of two or more solvents can be used. When using a solvent, from the viewpoint of achieving good coatability and forming a uniform release layer, the concentration of the non-volatile component of the release agent is preferably 40% by mass or less.

[0052] Coating methods used as release agents include, for example, wirebar coating, reverse coating, gravure coating, die coating, blade coating, dipping coating, air knife coating, curtain coating, and roller coating.

[0053] There are no particular limitations on the drying temperature of the mold release agent. In one example, drying can be carried out in a temperature range of 80°C to 130°C. In another example, drying can be carried out in a temperature range of 160°C to 240°C.

[0054] By applying a release agent to the surface of a supporting substrate and drying it as needed, a layer containing a non-volatile component of the release agent can be formed. This layer can be used as a release layer. Alternatively, the aforementioned layer containing the non-volatile component of the release agent can be subjected to a hardening treatment to obtain a release layer. Examples of hardening treatments include heat treatment and ultraviolet irradiation treatment. Generally, through the aforementioned hardening treatment, the polymerization and cross-linking reactions of some or all of the components contained in the release agent occur, which hardens the release agent, thus obtaining a release layer formed from the hardened release agent.

[0055] In addition, the manufacturing method of the support body may include any treatment such as stretching, as needed.

[0056] -Resin Composition Layer- The resin sheet has a resin composition layer formed on a release layer of a support. Typically, the resin composition layer is in contact with the release layer of the support, and no other layer is disposed between the release layer and the resin composition layer. This resin composition layer contains the resin composition, and preferably contains only the resin composition.

[0057] The resin composition contains (A) imidazole compounds. (A) imidazole compounds typically function as curing catalysts in the resin composition. Specifically, the resin composition typically contains (B) a thermosetting resin, and (A) imidazole compounds can function as catalysts that promote the curing reaction of (B) the thermosetting resin.

[0058] Examples of (A) imidazole compounds include, for example, 2-methylimidazolium, 2-undecylimidazolium, 2-heptadecylimidazolium, 1,2-dimethylimidazolium, 2-ethyl-4-methylimidazolium, 1,2-dimethylimidazolium, 2-ethyl-4-methylimidazolium, 2-phenylimidazolium, 2-phenyl-4-methylimidazolium, 1-benzyl-2-methylimidazolium, 1-benzyl-2-phenylimidazolium, 1-cyanoethyl-2-methylimidazolium, 1-cyanoethyl-2-undecylimidazolium, 1-cyanoethyl-2-ethyl-4-methylimidazolium, 1-cyanoethyl-2-phenylimidazolium, 1-cyanoethyl-2-undecylimidazolium trimellitate, 1-cyanoethyl-2-phenylimidazolium trimellitate, and 2,4-diamino-6-[2'-methylimidazolium-(1')] Imidazole compounds such as 2,4-diamino-6-[2'-undecylimidazolyl-(1')]-ethyl-triazine, 2,4-diamino-6-[2'-ethyl-4'-methylimidazolyl-(1')]-ethyl-triazine, 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-triazine isocyanuric acid adduct, 2-phenylimidazolyl isocyanuric acid adduct, 2-phenyl-4,5-dihydroxymethylimidazolium, 2-phenyl-4-methyl-5-hydroxymethylimidazolium, 2,3-dihydro-1H-pyrrolo[1,2-a]benzimidazole, 1-dodecyl-2-methyl-3-benzylimidazolium chloride, 2-methylimidazoline, 2-phenylimidazoline, etc.; and adducts of the aforementioned imidazole compounds with epoxy resins.

[0059] Commercially available (A) imidazole compounds can be used. Examples of commercially available (A) imidazole compounds include "1B2PZ", "2E4MZ", "2MZA-PW", "2MZ-OK", "2MA-OK", "2MA-OK-PW", "2PHZ", "2PHZ-PW", "C11Z", "C11Z-CN", "C11Z-CNS", and "C11Z-A" manufactured by Shikoku Chemical Co., Ltd.; and "P200-H50" manufactured by Mitsubishi Chemical Co., Ltd. One (A) imidazole compound can be used alone, or two or more can be used in combination.

[0060] The amount of (A) imidazole compounds in the resin composition relative to 100% by mass of the non-volatile components of the resin composition is preferably 0.01% by mass or more, more preferably 0.02% by mass or more, particularly preferably 0.03% by mass or more, preferably 1% by mass or less, more preferably 0.5% by mass or less, and particularly preferably 0.1% by mass or less.

[0061] The amount of (A) imidazole compounds in the resin composition relative to 100% by mass of the resin component is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, particularly preferably 0.1% by mass or more, preferably 5% by mass or less, more preferably 2% by mass or less, and particularly preferably 1% by mass or less. The resin component of the resin composition indicates the component from which the inorganic filler material (C) described later has been removed from the non-volatile components of the resin composition.

[0062] The resin composition typically includes (B) a thermosetting resin. As the (B) thermosetting resin, a resin capable of reacting upon application of heat to form a bond, thereby hardening the resin composition, can be used. Examples of (B) thermosetting resins include epoxy resins, phenolic resins, reactive ester resins, carbodiimide resins, acid anhydride resins, amine resins, benzoxazine resins, cyanate ester resins, and thiol resins. The (B) thermoplastic resin can be used alone or in combination of two or more.

[0063] Epoxy resins can be resins containing epoxy groups. Examples of epoxy resins include: bixylenol type epoxy resin, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, bisphenol AF type epoxy resin, dicyclopentadiene type epoxy resin, triphenol type epoxy resin, naphthol novolac type epoxy resin, phenol novolac type epoxy resin, tert-butyl-catechol type epoxy resin, naphthalene type epoxy resin, naphthol type epoxy resin, anthracene type epoxy resin, glycidylamine type epoxy resin, glycidyl ester type epoxy resin, and cresol novolac. Novolac type epoxy resins include phenolic aryl alkyl type epoxy resins, biphenyl type epoxy resins, linear aliphatic epoxy resins, butadiene-structured epoxy resins, alicyclic epoxy resins, heterocyclic epoxy resins, spirocyclic epoxy resins, cyclohexane type epoxy resins, cyclohexanediethanol type epoxy resins, naphthyl ether type epoxy resins, tris(hydroxymethyl) type epoxy resins, tetraphenylethane type epoxy resins, isocyanurate type epoxy resins, and phenolphthalimidine type epoxy resins, etc. Epoxy resins can be used alone or in combination of two or more.

[0064] From the perspective of obtaining an insulating layer with excellent heat resistance, epoxy resins containing aromatic structures are preferable. Aromatic structures are generally defined as aromatic chemical structures, including polycyclic aromatics and aromatic heterocycles. Examples of epoxy resins containing aromatic structures include bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, bisphenol AF type epoxy resin, dicyclopentadiene type epoxy resin, triphenol type epoxy resin, naphthol phenolic varnish type epoxy resin, phenol phenolic varnish type epoxy resin, tert-butylcatechol type epoxy resin, naphthyl type epoxy resin, naphthol type epoxy resin, anthracene type epoxy resin, bixylenol type epoxy resin, glycidylamine type epoxy resin with aromatic structures, and glycidylamine type epoxy resin with aromatic structures. Glyceryl ester type epoxy resin, cresol phenolic varnish type epoxy resin, biphenyl type epoxy resin, linear aliphatic epoxy resin with aromatic structure, butadiene type epoxy resin with aromatic structure, alicyclic epoxy resin with aromatic structure, heterocyclic epoxy resin, spirocyclic epoxy resin with aromatic structure, cyclohexanediol type epoxy resin with aromatic structure, naphthyl ether type epoxy resin, trihydroxymethyl type epoxy resin with aromatic structure, tetraphenylethane type epoxy resin with aromatic structure, etc.

[0065] The resin composition is preferably an epoxy resin containing two or more epoxy groups per molecule. The proportion of epoxy resin containing two or more epoxy groups per molecule is preferably 50% by mass or more, more preferably 60% by mass or more, and particularly preferably 70% by mass or more, relative to 100% by mass of the total non-volatile components of the epoxy resin.

[0066] Epoxy resins include epoxy resins that are liquid at 20°C (hereinafter sometimes referred to as "liquid epoxy resins") and epoxy resins that are solid at 20°C (hereinafter sometimes referred to as "solid epoxy resins"). In a resin composition, the epoxy resin may consist only of liquid epoxy resin, or only of solid epoxy resin, or a combination of both.

[0067] As a liquid epoxy resin, it is preferable to be a liquid epoxy resin having two or more epoxy groups in one molecule.

[0068] As liquid epoxy resins, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol AF type epoxy resin, naphthalene type epoxy resin, glycidyl ester type epoxy resin, glycidylamine type epoxy resin, phenolic varnish type epoxy resin, alicyclic epoxy resin with ester skeleton, cyclohexane type epoxy resin, cyclohexanediethanol type epoxy resin, and epoxy resin with butadiene structure are preferred.

[0069] Specific examples of liquid epoxy resins include: DIC's "HP4032", "HP4032D", and "HP4032SS" (naphthalene-type epoxy resin); and Mitsubishi Chemical's "828US", "828EL", "jER828EL", "825", and "EPIKOTE". 828EL (Bisphenol A type epoxy resin); "jER807" and "1750" (Bisphenol F type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "jER152" (Phenolic varnish type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "630", "630LSD", and "604" (Glycidylamine type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "ED-523T" (Glycirol type epoxy resin) manufactured by ADEKA Corporation; "EP-3950L" and "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 Materials Co., Ltd.; "EX-721" (Glycidyl ester type epoxy resin) manufactured by Nagase ChemteX Corporation; "Celloxide" manufactured by Daicel Corporation. 2021P (alicyclic epoxy resin with an ester skeleton); Daicel's "PB-3600"; Nippon Soda's "JP-100" and "JP-200" (epoxy resins with a butadiene structure); JITAC Chemical Materials' "ZX1658" and "ZX1658GS" (liquid 1,4-glycidylcyclohexane type epoxy resin); and Mitsubishi Chemical's "YX8000" (hydrogenated bisphenol A type epoxy resin), etc. These can be used individually or in combination of two or more.

[0070] As a solid epoxy resin, it is preferable to be a solid epoxy resin having three or more epoxy groups in one molecule, and more preferably an aromatic solid epoxy resin having three or more epoxy groups in one molecule.

[0071] As solid epoxy resins, the preferred types are xylenol-type epoxy resins, naphthalene-type epoxy resins, naphthalene-type tetrafunctional epoxy resins, naphthol phenolic varnish-type epoxy resins, cresol phenolic varnish-type epoxy resins, dicyclopentadiene-type epoxy resins, triphenol-type epoxy resins, naphthol-type epoxy resins, biphenyl-type epoxy resins, naphthyl ether-type epoxy resins, anthracene-type epoxy resins, bisphenol A-type epoxy resins, bisphenol AF-type epoxy resins, phenol aralkyl-type epoxy resins, tetraphenylethane-type epoxy resins, and phenol benzopyrrolidone-type epoxy resins.

[0072] Specific examples of solid epoxy resins include: DIC's "HP4032H" (naphthalene-type epoxy resin); DIC's "HP-4700" and "HP-4710" (naphthalene-type tetrafunctional epoxy resins); DIC's "N-690" (cresol phenolic varnish type epoxy resin); DIC's "N-695" (cresol phenolic varnish type epoxy resin); DIC's "HP-7200," "HP-7200HH," "HP-7200H," and "HP-7200L" (dicyclopentadiene type epoxy resin); DIC... The following are listed: "EXA-7311", "EXA-7311-G3", "EXA-7311-G4", "EXA-7311-G4S", and "HP6000" (naphthyl ether type epoxy resin); "EPPN-502H" (triphenol type epoxy resin) manufactured by Nippon Kayaku Co., Ltd.; "NC7000L" (naphthol phenolic varnish 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.; [The last sentence appears to be incomplete and possibly refers to a different product or company.] The following epoxy resins are manufactured by Jitsugaku Chemical Materials Co., Ltd.: "ESN475V" and "ESN4100V" (naphthalene-type epoxy resin); "ESN485" (naphthol-type epoxy resin); "ESN375" (dihydroxynaphthalene-type epoxy resin); "YX4000H," "YX4000," "YX4000HK," and "YL7890" (bi-xylenol-type epoxy resin); "YL6121" (biphenyl-type epoxy resin); and "YX8800" (anthracite-type epoxy resin). The following are epoxy resins manufactured by Mitsubishi Chemical Corporation: YX7700 (phenolic aralkyl type epoxy resin); PG-100 and CG-500 (Osaka Gas Chemical Co., Ltd.); YL7760 (bisphenol AF type epoxy resin); YL7800 (fluorene type epoxy resin); jER1010 (bisphenol A type epoxy resin); jER1031S (tetraphenylethane type epoxy resin); and WHR991S (phenolic benzopyrrolidone type epoxy resin). These can be used individually or in combination with other resins.

[0073] When using liquid and solid epoxy resins in combination, the ideal ratio of their quality (liquid epoxy resin: solid epoxy resin) is 20:1 to 1:20, even better is 10:1 to 1:10, and particularly good is 7:1 to 1:7.

[0074] The epoxy equivalent of epoxy resin is preferably 50 g / eq. to 5000 g / eq., more preferably 60 g / eq. to 3000 g / eq., further preferably 80 g / eq. to 2000 g / eq., and particularly preferably 110 g / eq. to 1000 g / eq. Epoxy equivalent represents the mass of resin per equivalent of epoxy groups. This epoxy equivalent can be determined according to JIS K7236.

[0075] The weight-average molecular weight (Mw) of epoxy resin is preferably 100–5000, more preferably 250–3000, and even more preferably 400–1500. The weight-average molecular weight of the resin can be determined using gel permeation chromatography (GPC) as a conversion value to polystyrene.

[0076] The amount of epoxy resin in the resin composition is, relative to 100% by mass of the non-volatile components in the resin composition, preferably 1% by mass or more, more preferably 5% by mass or more, particularly preferably 10% by mass or more, preferably less than 50% by mass, more preferably less than 40% by mass, and particularly preferably less than 30% by mass.

[0077] The amount of epoxy resin in the resin composition is, relative to 100% by mass of the resin component in the resin composition, preferably 10% by mass or more, more preferably 30% by mass or more, particularly preferably 50% by mass or more, preferably 90% by mass or less, more preferably 85% by mass or less, and particularly preferably 80% by mass or less.

[0078] Phenolic resins can be resins having one or more, preferably two or more, hydroxyl groups bonded to aromatic rings such as benzene rings or naphthalene rings in one molecule. From the viewpoint of heat resistance and water resistance, phenolic resins with a novolak structure are preferred. Furthermore, from the viewpoint of adhesion, nitrogen-containing phenolic resins are preferred, and phenolic resins containing a triazine skeleton are even more preferred. Among these, from the viewpoint of highly satisfying heat resistance, water resistance, and adhesion, linear phenolic resins containing a triazine skeleton are preferred.

[0079] Specific examples of phenolic resins include: "MEH-7700", "MEH-7810", and "MEH-7851" manufactured by Meiwa Kasei Corporation; "NHN", "CBN", and "GPH" manufactured by Nippon Kayaku Co., Ltd.; "SN-170", "SN-180", "SN-190", "SN-475", "SN-485", "SN-495", "SN-375", and "SN-395" manufactured by JITAC Chemical Materials Co., Ltd.; and "LA-7052", "LA-7054", "LA-3018", "LA-3018-50P", "LA-1356", "TD2090", and "TD-2090-60M" manufactured by DIC Corporation. Phenolic resins can be used alone or in combination of two or more.

[0080] The amount of phenolic resin in the resin composition relative to the non-volatile components in the resin composition is 100% by weight, preferably 0.1% by weight or more, more preferably 0.5% by weight or more, particularly preferably 1% by weight or more, preferably less than 50% by weight, more preferably less than 40% by weight, and particularly preferably less than 30% by weight.

[0081] The amount of phenolic resin in the resin composition relative to 100% by weight of the resin content in the resin composition is preferably 0.1% or more by weight, more preferably 1% or more by weight, particularly preferably 3% or more by weight, preferably less than 60% by weight, more preferably less than 50% by weight, and particularly preferably less than 40% by weight.

[0082] An active ester resin can be a resin having one or more active ester groups in one molecule. The active ester group can be an ester bond directly bonded to an aromatic ring. Generally, it is preferable to use compounds with two or more highly reactive ester groups in one molecule, such as phenolic esters, thiophenolic esters, N-hydroxyamine esters, or esters of heterocyclic hydroxyl compounds. This active ester resin is preferably a compound obtained through a condensation reaction of a carboxylic acid compound and / or a thiocarboxylic acid compound with a hydroxyl compound and / or a thiol compound. Especially from the viewpoint of improved heat resistance, an active ester resin obtained from a carboxylic acid compound and a hydroxyl compound is preferred, and an active ester resin obtained from a carboxylic acid compound and a phenolic compound and / or a naphthol compound is even more preferred. Examples of carboxylic acid compounds include benzoic acid, acetic acid, succinic acid, maleic acid, itaconic acid, phthalic acid, isophthalic acid, terephthalic acid, and pyromellitic acid. Examples of phenolic or naphthol compounds include hydroquinone, resorcinol, bisphenol A, bisphenol F, bisphenol S, phenolphthalein, methylated bisphenol A, methylated bisphenol F, methylated bisphenol S, phenol, o-cresol, m-cresol, p-cresol, catechol, α-naphthol, β-naphthol, 1,5-dihydroxynaphthol, 1,6-dihydroxynaphthol, 2,6-dihydroxynaphthol, dihydroxybenzophenone, trihydroxybenzophenone, tetrahydroxybenzophenone, phloroglucinol, pyroglucinol, dicyclopentadiene-type diphenol compounds, and linear phenolic resins. Here, "dicyclopentadiene-type diphenol compounds" refers to diphenol compounds obtained by condensing one molecule of dicyclopentadiene with two molecules of phenol.

[0083] Specifically, the preferred active ester resins are dicyclopentadiene-type active ester resins, naphthalene-type active ester resins containing a naphthalene structure, active ester resins containing acetylated linear phenolic resins, and active ester resins containing benzoylated linear phenolic resins. More preferably, at least one type selected from dicyclopentadiene-type and naphthalene-type active ester resins is preferred. As a dicyclopentadiene-type active ester resin, an active ester resin containing a dicyclopentadiene-type diphenol structure is preferred.

[0084] Commercially available reactive ester resins include, for example, those containing a dicyclopentadiene-type diphenol structure such as "EXB9451", "EXB9460", "EXB9460S", "EXB-8000L", "EXB-8000L-65M", "EXB-8000L-65TM", "HPC-8000L-65TM", "HPC-8000", "HPC-8000-65T", "HPC-8000H", and "HPC-8000H-65TM" (manufactured by DIC Corporation); and reactive ester resins containing a naphthalene structure such as "HP-B-8151-62T", "EXB-8100L-65T", and "EXB-8150-60T". "EXB-8150-62T", "EXB-9416-70BK", "HPC-8150-60T", "HPC-8150-62T", and "EXB-8" (manufactured by DIC Corporation); "EXB9401" (manufactured by DIC Corporation) is an example of a phosphorus-containing reactive ester resin; "DC808" (manufactured by Mitsubishi Chemical Corporation) is an example of a reactive ester resin containing acetylated linear phenolic resins; "YLH1026", "YLH1030", and "YLH1048" (manufactured by Mitsubishi Chemical Corporation) are examples of reactive ester resins containing styrene and naphthalene structures; and "PC1300-02-65MA" (manufactured by AIR WATER Corporation) is an example of such a reactive ester resin. Active ester resins can be used alone or in combination with two or more.

[0085] The amount of active ester resin in the resin composition relative to the non-volatile components in the resin composition is 100% by weight, preferably 0.1% by weight or more, more preferably 0.5% by weight or more, particularly preferably 1% by weight or more, preferably less than 50% by weight, more preferably less than 40% by weight, and particularly preferably less than 30% by weight.

[0086] The amount of active ester resin in the resin composition is, relative to 100% by weight of the resin content in the resin composition, preferably 0.1% by weight or more, more preferably 1% by weight or more, particularly preferably 3% by weight or more, preferably less than 60% by weight, more preferably less than 50% by weight, and particularly preferably less than 40% by weight.

[0087] Carbodiimide resins can be resins having one or more, preferably two or more, carbodiimide structures in one molecule. Examples of carbodiimide resins include dicarbodiimides and polycarbodiimides. Specific examples of dicarbodiimides include aliphatic dicarbodiimides such as tetramethylene-bis(tert-butylcarbodiimide) and cyclohexane-bis(methylene-tert-butylcarbodiimide); and aromatic dicarbodiimides such as phenyl-bis(xylylcarbodiimide). Specific examples of polycarbodiimides include aliphatic polycarbodiimides such as polyhexamethylene carbodiimide, polytrimethylhexamethylene carbodiimide, polycyclohexylcarbodiimide, poly(methylene bis(cyclohexylcarbodiimide), poly(isophorone carbodiimide); and aromatic polycarbodiimides such as poly(phenylcarbodiimide), poly(naphthylcarbodiimide), poly(methylphenylcarbodiimide), poly(methyldiisopropylphenylcarbodiimide), poly(triethylphenylcarbodiimide), poly(diethylphenylcarbodiimide), poly(triisopropylphenylcarbodiimide), poly(diisopropylphenylcarbodiimide), poly(xylylcarbodiimide), poly(tetramethylxylylcarbodiimide), poly(methylene bis(methylphenyl)carbodiimide). Commercially available carbodiimide resins include, for example, "CARBODILITE V-02B," "CARBODILITE V-03," "CARBODILITE V-04K," "CARBODILITE V-07," and "CARBODILITE V-09" manufactured by Nisshinbo Chemical Co., Ltd.; and "Stabaxol P," "Stabaxol P400," and "Hycasyl 510" manufactured by Rhein Chemie. Carbodiimide resins can be used alone or in combination of two or more types.

[0088] Anhydride resins can be resins having one or more anhydride groups in one molecule, preferably resins having two or more anhydride groups in one molecule. Specific examples of anhydride resins include phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, methylnadic anhydride, hydrogenated methylnadic anhydride, trialkyltetrahydrophthalic anhydride, dodecenylsuccinic anhydride, 5-(2,5-dioxotetrahydro-3-furanyl)-3-methyl-3-cyclohexene-1,2-dicarboxylic anhydride, trimellitic anhydride, pyromellitic anhydride, and diphenylmethane. Polymer-type anhydrides such as ketone tetracarboxylic dianhydride, biphenyl tetracarboxylic dianhydride, naphthalene tetracarboxylic dianhydride, oxobis(phthalic acid) dianhydride, 3,3'-4,4'-diphenyltrimethyltetracarboxylic 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(trimethoxybenzoic acid ester), and styrene-maleic acid resin obtained by copolymerizing styrene with maleic acid. Commercially available anhydride resins include, for example, those manufactured by Shin Nippon Rika Co., Ltd. such as "HNA-100", "MH-700", "MTA-15", "DDSA", and "OSA"; those manufactured by Mitsubishi Chemical Co., Ltd. such as "YH-306" and "YH-307"; those manufactured by Hitachi Chemical Co., Ltd. such as "HN-2200" and "HN-5500"; and those manufactured by Cray Valley Co., Ltd. such as "EF-30", "EF-40", "EF-60", and "EF-80". Anhydride resins can be used alone or in combination of two or more.

[0089] Amine resins can be resins having one or more, preferably two or more, amine groups in one molecule. Examples of amine resins include aliphatic amines, polyether amines, alicyclic amines, and aromatic amines, with aromatic amines being preferred. Amine resins are preferably primary or secondary amines, and more preferably primary amines. Specific examples of amine resins include 4,4'-methylenebis(2,6-dimethylaniline), 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenyl sulfone, 3,3'-diaminodiphenyl sulfone, m-phenylenediamine, m-phenylenediamine, diethyltoluenediamine, 4,4'-diaminodiphenyl ether, 3,3'-dimethyl-4,4'-diaminobiphenyl, 2,2'-dimethyl-4,4'-diaminobiphenyl, 3,3'-dihydroxybenzidine, and 2,2-bis(3-amino-4-hydroxy)benzidine. 2,2-bis(4-aminophenyl)propane, 3,3-dimethyl-5,5-diethyl-4,4-diphenylmethanediamine, 2,2-bis(4-aminophenyl)propane, 2,2-bis(4-(4-aminophenoxy)phenyl)propane, 1,3-bis(3-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, 1,4-bis(4-aminophenoxy)benzene, 4,4'-bis(4-aminophenoxy)biphenyl, bis(4-(4-aminophenoxy)phenyl) benzoxide, bis(4-(3-aminophenoxy)phenyl) benzoxide, etc. Commercially available amine resins include, for example, "SEIKACURE-S" manufactured by SEIKA Corporation; "KAYABOND C-200S", "KAYABOND C-100", "KAYAHARD AA", "KAYAHARD AB", and "KAYAHARD AS" manufactured by Nippon Kayaku Co., Ltd.; "Epicure W" manufactured by Mitsubishi Chemical Co., Ltd.; and "DTDA" manufactured by Sumitomo Seika Co., Ltd. Amine resins can be used alone or in combination of two or more.

[0090] Specific examples of benzoxazine resins include "JBZ-OP100D" and "ODA-BOZ" manufactured by JFE Chemical Co., Ltd.; "HFB2006M" manufactured by Showa Polymer Co., Ltd.; and "Pd" and "Fa" manufactured by Shikoku Chemical Co., Ltd. Benzoxazine resins can be used alone or in combination of two or more types.

[0091] Cyanate ester resin can be a resin having one or more, preferably two or more, cyanate ester groups in one molecule. Examples of difunctional cyanate resins include bisphenol A dicyanate, polyphenol cyanate (oligomeric (3-methylene-1,5-phenyl cyanate)), 4,4'-methylenebis(2,6-dimethylphenyl cyanate), 4,4'-ethylidene diphenyl dicyanate, hexafluorobisphenol A dicyanate, 2,2-bis(4-cyanate)phenylpropane, 1,1-bis(4-cyanate-phenylmethane), bis(4-cyanate-3,5-dimethylphenyl)methane, 1,3-bis(4-cyanate-phenyl-1-(methylethylidene))benzene, bis(4-cyanate-phenyl) sulfide, and bis(4-cyanate-phenyl) ether; multifunctional cyanate resins derived from phenolic varnish resins and cresol varnish resins; and prepolymers obtained by partially triazinizing these cyanate resins. Specific examples of cyanate ester resins include "PT30" and "PT60" (both linear phenolic varnish-type multifunctional cyanate ester resins) manufactured by Lonza Japan, "BA230" and "BA230S75" (prepolymers obtained by triazinizing part or all of bisphenol A dicyanate to form a trimer), etc. A single cyanate ester resin can be used alone, or two or more can be used in combination.

[0092] Examples of thiol resins include trimethylolpropane tris(3-mercaptopropionate), pentaerythritol tetra(3-mercaptobutyrate), and tris(3-mercaptopropyl)isocyanurate. A single thiol resin can be used alone, or two or more can be used in combination.

[0093] In a preferred embodiment, (B) the thermosetting resin comprises an epoxy resin. In a more preferred embodiment, (B) the thermosetting resin composition comprises an "epoxy resin" and a "resin that can react with the epoxy resin to cure the resin composition". Hereinafter, the resin that can react with the epoxy resin to cure the resin composition is sometimes referred to as an "epoxy curing agent". Examples of epoxy curing agents include phenolic resins, reactive ester resins, carbodiimide resins, acid anhydride resins, amine resins, benzoxazine resins, cyanate ester resins, and thiol resins. Phenolic resins and reactive ester resins are preferred among epoxy curing agents. One type of epoxy curing agent may be used alone, or two or more may be used in combination.

[0094] The active group equivalent of the epoxy curing agent is preferably 50 g / eq. to 3000 g / eq., more preferably 100 g / eq. to 1000 g / eq., further preferably 100 g / eq. to 500 g / eq., and particularly preferably 100 g / eq. to 300 g / eq. The active group equivalent indicates the mass of epoxy curing agent per 1 equivalent of active group.

[0095] When epoxy resin and epoxy curing agent are used in combination, the ratio of the number of epoxy groups in the epoxy resin to the number of active groups in the epoxy curing agent (“number of active groups in the epoxy curing agent” / “number of epoxy groups in the epoxy resin”) is preferably within a specific range. Specifically, the aforementioned ratio (“number of active groups in the epoxy curing agent” / “number of epoxy groups in the epoxy resin”) is preferably 0.1 or more, more preferably 0.2 or more, further preferably 0.3 or more, preferably 5.0 or less, more preferably 3.0 or less, and particularly preferably 1.5 or less. “Number of epoxy groups in the epoxy resin” refers to the sum of all values ​​obtained by dividing the mass of the non-volatile component of the epoxy resin present in the resin composition by the epoxy equivalent. Similarly, “number of active groups in the epoxy curing agent” refers to the sum of all values ​​obtained by dividing the mass of the non-volatile component of the epoxy curing agent present in the resin composition by the active group equivalent of the epoxy curing agent.

[0096] The amount of (B) thermosetting resin in the resin composition is 100% by mass of the non-volatile components of the resin composition, preferably 5% by mass or more, more preferably 10% by mass or more, particularly preferably 20% by mass or more, preferably 70% by mass or less, more preferably 60% by mass or less, and particularly preferably 50% by mass or less.

[0097] The amount of (B) thermosetting resin in the resin composition is, relative to 100% by mass of the resin component of the resin composition, preferably 60% by mass or more, more preferably 70% by mass or more, particularly preferably 80% by mass or more, preferably 99.9% by mass or less, and more preferably 99% by mass or less.

[0098] The mass ratio of (B) thermosetting resin to (A) imidazole compound in the resin composition ((B) thermosetting resin / (A) imidazole compound) is preferably 100 or more, more preferably 200 or more, further preferably 300 or more, particularly preferably 400 or more, preferably 1000 or less, more preferably 900 or less, further preferably 800 or less, and particularly preferably 700 or less.

[0099] The resin composition may further include (C) inorganic filler materials. (C) Inorganic filler materials are typically included in the resin composition in the form of particles.

[0100] Inorganic compounds are used as materials for (C) inorganic filler. Examples of materials for (C) inorganic filler include, for example, silicon dioxide, 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. Among these, silicon dioxide and alumina are suitable, and silicon dioxide is particularly suitable. Examples of silicon dioxide include, for example, amorphous silicon dioxide, fused silicon dioxide, crystalline silicon dioxide, synthetic silicon dioxide, and hollow silicon dioxide. Furthermore, spherical silicon dioxide is preferred as the silicon dioxide. (C) Inorganic filler materials may be used alone or in combination of two or more.

[0101] Commercially available products as (C) inorganic filler materials include, for example, “SP60-05” and “SP507-05” manufactured by Nippon Steel Chemical Materials Co., Ltd.; “YC100C”, “YA050C”, “YA050C-MJE”, “YA010C”, “SC2500SQ”, “SO-C4”, “SO-C2”, “SO-C1”, and “SC2050-SXF” manufactured by Admatechs Co., Ltd.; “UFP-30” manufactured by Denka Co., Ltd.; and “Silfil NSS-3N”, “Silfil NSS-4N”, and “Silfil NSS-5N” manufactured by Tokuyama Co., Ltd.

[0102] (C) The average particle size of the inorganic filler material is preferably 0.01 μm or more, more preferably 0.05 μm or more, even more preferably 0.1 μm or more, particularly preferably 0.2 μm or more, preferably 10 μm or less, more preferably 5 μm or less, even more preferably 2 μm or less, and particularly preferably 1 μm or less.

[0103] (C) The average particle size of inorganic filler materials can be determined by laser diffraction-scattering based on the Mie scattering theory. Specifically, a laser diffraction-scattering particle size distribution measuring device can be used to prepare the particle size distribution of the inorganic filler material on a volume basis, and the median particle size can be used as the average particle size for measurement. The sample for measurement can be obtained by weighing 100 mg of inorganic filler material and 10 g of methyl ethyl ketone into a tube and dispersing it ultrasonically for 10 minutes. For the sample for measurement, a laser diffraction-scattering particle size distribution measuring device is used, with the light source wavelength set to blue and red, and the volume-based particle size distribution of the inorganic filler material is measured in a flow cell manner. The average particle size can be calculated based on the obtained particle size distribution as the median particle size. Examples of laser diffraction-scattering particle size distribution measuring devices include the "LA-960" manufactured by (tsubo)Horiba Corporation.

[0104] (C) The specific surface area of ​​the inorganic filler material is preferably 0.1 m² / g or more, more preferably 0.5 m² / g or more, further preferably 1 m² / g or more, particularly preferably 3 m² / g or more, preferably below 100 m² / g, more preferably below 70 m² / g, further preferably below 50 m² / g, and particularly preferably below 40 m² / g. The specific surface area of ​​the inorganic filler material can be determined as follows: according to the BET method, nitrogen gas is adsorbed onto the sample surface using a specific surface area measuring device (Macsorb HM-1210 manufactured by Mountech), and the specific surface area is calculated using the BET multi-point method.

[0105] From the perspective of improving moisture resistance and dispersibility, (C) inorganic filler materials are preferably treated with surface treatment agents. Examples of surface treatment agents include fluorinated silane coupling agents, aminosilane coupling agents, epoxysilane coupling agents, mercaptosilane coupling agents, silane coupling agents, alkoxysilanes, organosilazane compounds, titanate coupling agents, etc. A single surface treatment agent can be used, or two or more can be used in any combination.

[0106] Commercially available surface treatment agents include, for example, "KBM403" (3-epoxypropoxypropyltrimethoxysilane) manufactured by Shin-Etsu Chemical Industry Co., Ltd., "KBM803" (3-mercaptopropyltrimethoxysilane) manufactured by Shin-Etsu Chemical Industry Co., Ltd., "KBE903" (3-aminopropyltriethoxysilane) manufactured by Shin-Etsu Chemical Industry Co., Ltd., "KBM573" (N-phenyl-3-aminopropyltrimethoxysilane) manufactured by Shin-Etsu Chemical Industry Co., Ltd., "SZ-31" (hexamethyldisilazane) manufactured by Shin-Etsu Chemical Industry Co., Ltd., "KBM103" (phenyltrimethoxysilane) manufactured by Shin-Etsu Chemical Industry Co., Ltd., "KBM-4803" (long-chain epoxy silane coupling agent) manufactured by Shin-Etsu Chemical Industry Co., Ltd., and "KBM-7103" (3,3,3-trifluoropropyltrimethoxysilane) manufactured by Shin-Etsu Chemical Industry Co., Ltd.

[0107] From the perspective of improving the dispersibility of inorganic fillers, the degree of surface treatment with surface treatment agents should preferably be controlled within a specific range. Specifically, it is preferable that 100% by mass of the inorganic filler has been surface treated with 0.2% to 5% by mass of surface treatment agent, more preferably with 0.2% to 3% by mass of surface treatment agent, and even more preferably with 0.3% to 2% by mass of surface treatment agent.

[0108] The degree of surface treatment with a surface treatment agent can be evaluated by the carbon content per unit surface area of ​​the inorganic filler. From the viewpoint of improving the dispersibility of the inorganic filler, the carbon content per unit surface area of ​​the inorganic filler is preferably 0.02 mg / m² or more, more preferably 0.1 mg / m² or more, and even more preferably 0.2 mg / m² or more. On the other hand, from the viewpoint of preventing an increase in the melt viscosity of the resin composition, it is preferably 1.0 mg / m² or less, more preferably 0.8 mg / m² or less, and even more preferably 0.5 mg / m² or less.

[0109] (C) The carbon content per unit surface area of ​​the inorganic filler material can be determined after cleaning the surface-treated inorganic filler material with a solvent (e.g., methyl ethyl ketone (MEK)). Specifically, sufficient MEK as a solvent is added to the surface-treated inorganic filler material, and ultrasonic cleaning is performed at 25°C for 5 minutes. After removing the supernatant and drying the solid components, the carbon content per unit surface area of ​​the inorganic filler material can be determined using a carbon analyzer. A carbon analyzer such as the "EMIA-320V" manufactured by Horiba Corporation can be used.

[0110] The amount of inorganic filler (C) in the resin composition is approximately 20% or more, more preferably 40% or more, particularly preferably 60% or more, more preferably less than 90% or more, more preferably less than 85% or more, and particularly preferably less than 80% or more, relative to 100% of the non-volatile components in the resin composition.

[0111] The resin composition may further include (D) thermoplastic resin. This (D) thermoplastic resin does not include substances belonging to (A) imidazole compounds, (B) thermosetting resins, or (C) inorganic fillers.

[0112] Examples of (D) thermoplastic resins include phenoxy resins, polyimide resins, polyvinyl alcohol acetal resins, polyolefin resins, polybutadiene resins, polyamide-imide resins, polyether-imide resins, polyurethane resins, polyphenylene ether resins, polycarbonate resins, polyether ether ketone resins, and polyester resins. (D) Thermoplastic resins can be used alone or in combination of two or more.

[0113] Examples of phenoxy resins include those having one or more skeletons selected from the following: bisphenol A skeleton, bisphenol F skeleton, bisphenol S skeleton, bisphenol acetobenzene skeleton, phenolic skeleton, biphenyl skeleton, fluorene skeleton, dicyclopentadiene skeleton, norbornene skeleton, naphthalene skeleton, anthracene skeleton, adamantane skeleton, terpene skeleton, and trimethylcyclohexane skeleton. The terminal group of the phenoxy resin can be any functional group selected from phenolic hydroxyl groups, epoxy groups, etc. Specific examples of phenoxy resins include Mitsubishi Chemical's "1256" and "4250" (both containing a bisphenol A backbone); Mitsubishi Chemical's "YX8100" (containing a bisphenol S backbone); Mitsubishi Chemical's "YX6954" (containing a bisphenol acetobenzene backbone); Nippon Steel & Sumitomo Metal Chemicals' "FX280" and "FX293"; Mitsubishi Chemical's "YL7500BH30", "YX6954BH30", "YX7553", "YX7553BH30", "YL7769BH30", "YL6794", "YL7213", "YL7290", "YL7482", and "YL7891BH30"; etc.

[0114] Specific examples of polyimide resins include "SLK-6100" manufactured by Shin-Etsu Chemical Industry Co., Ltd., and "RIKACOAT SN20" and "RIKACOAT PN20" manufactured by Shin Nippon Rika Co., Ltd. Other specific examples of polyimide resins include linear polyimides (the polyimides described in Japanese Patent Application Publication No. 2006-37083) obtained by reacting difunctional hydroxyl-terminated polybutadiene, diisocyanate compounds, and tetracarboxylic anhydrides, and modified polyimides containing a polysiloxane backbone (the polyimides described in Japanese Patent Application Publication Nos. 2002-12667 and 2000-319386, etc.).

[0115] Examples of polyvinyl alcohol acetal resins include polyvinyl alcohol formal resin and polyvinyl alcohol butyral resin, with polyvinyl alcohol butyral resin being preferred. Specific examples of polyvinyl alcohol acetal resins include "Denka Butyral 4000-2", "Denka Butyral 5000-A", "Denka Butyral 6000-C", and "Denka Butyral 6000-EP" manufactured by Denka Kogyo Co., Ltd., and the S-LEC BH series, BX series (e.g., BX-5Z), KS series (e.g., KS-1), BL series, and BM series manufactured by Sekisui Chemicals Co., Ltd.

[0116] Examples of polyolefin resins include low-density polyethylene, ultra-low-density polyethylene, high-density polyethylene, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, ethylene-methyl acrylate copolymer, and other ethylene-based copolymer resins; and polyolefin polymers such as polypropylene and ethylene-propylene block copolymers.

[0117] Examples of polybutadiene resins include resins containing a hydrogenated polybutadiene backbone, polybutadiene resins containing hydroxyl groups, polybutadiene resins containing phenolic hydroxyl groups, polybutadiene resins containing carboxyl groups, polybutadiene resins containing acid anhydride groups, polybutadiene resins containing epoxy groups, polybutadiene resins containing isocyanate groups, polybutadiene resins containing urethane groups, and polyphenylene ether-polybutadiene resins.

[0118] Specific examples of polyamide-imide resins include "VYLOMAX HR11NN" and "VYLOMAX HR16NN" manufactured by Toyobo Co., Ltd. Other specific examples of polyamide-imide resins include modified polyamides such as "KS9100" and "KS9300" (polyamide-imide containing a polysiloxane backbone) manufactured by Hitachi Chemical Co., Ltd.

[0119] Specific examples of polyether resins include "PES5003P" manufactured by Sumitomo Chemical Co., Ltd.

[0120] Specific examples of polyurethane resins include "P1700" and "P3500" manufactured by Solvay Advanced Polymers.

[0121] Specific examples of polyphenylene ether resins include SABIC's "NORYL SA90". Specific examples of polyetherimide resins include GE's "ULTEM".

[0122] Examples of polycarbonate resins include hydroxyl-containing carbonate resins, phenolic hydroxyl-containing carbonate resins, carboxyl-containing carbonate resins, anhydride-containing carbonate resins, isocyanate-containing carbonate resins, and aminocarbamate-containing carbonate resins. Specific examples of polycarbonate resins include "FPC0220" manufactured by Mitsubishi Gas Chemical Co., Ltd., "T6002" and "T6001" (polycarbonate diol) manufactured by Asahi Kasei Chemical Co., Ltd., and "C-1090," "C-2090," and "C-3090" (polycarbonate diol) manufactured by Kuraray Co., Ltd. Specific examples of polyetheretherketone (PEEK) resins include "SUMIPLOY K" manufactured by Sumitomo Chemical Co., Ltd.

[0123] Examples of polyester resins include polyethylene terephthalate resin, polyethylene naphthalate resin, polybutylene terephthalate resin, polybutylene naphthalate resin, polypropylene terephthalate resin, polypropylene naphthalate resin, and polycyclohexanediol terephthalate resin.

[0124] (D) The weight-average molecular weight (Mw) of the thermoplastic resin is preferably greater than 5,000, more preferably greater than 8,000, even more preferably greater than 10,000, especially preferably greater than 20,000, preferably less than 100,000, more preferably less than 70,000, even more preferably less than 60,000, and especially preferably less than 50,000.

[0125] The amount of (D) thermoplastic resin in the resin composition relative to 100% by mass of the non-volatile components in the resin composition is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, particularly preferably 0.2% by mass or more, preferably 20% by mass or less, more preferably 10% by mass or less, and particularly preferably 5% by mass or less.

[0126] The amount of (D) thermoplastic resin in the resin composition is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, particularly preferably 1% by mass or more, preferably 30% by mass or less, more preferably 20% by mass or less, and particularly preferably 10% by mass or less, relative to 100% by mass of the resin component in the resin composition.

[0127] The resin composition may further include (E) a flame retardant. (E) The flame retardant does not include substances belonging to (A) imidazole compounds, (B) thermosetting resins, (C) inorganic fillers, or (D) thermoplastic resins. Examples of (E) flame retardants include phosphazene compounds, organophosphorus flame retardants, organic nitrogen-containing phosphorus compounds, nitrogen compounds, organosilicon flame retardants, and metal hydroxides. A single flame retardant may be used, or two or more may be used in combination.

[0128] Examples of flame retardants include "SPH-100", "SPS-100", "SPB-100", and "SPE-100" (phosphazenes) manufactured by Otsuka Chemical Co., Ltd.; "FP-100", "FP-110", "FP-300", and "FP-400" (phosphazenes) manufactured by Fushimi Pharmaceutical Co., Ltd.; "HCA-NQ", "HCA-HQ", and "HCA-HQ-HST" (phosphonates (containing phenolic hydroxyl groups)) manufactured by Sanko Co., Ltd.; and "PX-200", "PX-201", "PX-202", "CR-733S", "CR-741", and "CR-747" (phosphate esters) manufactured by Daihachi Chemical Industry Co., Ltd.

[0129] The amount of flame retardant (E) in the resin composition is preferably 0.1% by mass or more, more preferably 0.2% by mass or more, and even more preferably 0.3% by mass or more, relative to 100% by mass of the non-volatile components in the resin composition. The upper limit is preferably 5% by mass or less, more preferably 3% by mass or less, and even more preferably 1% by mass or less.

[0130] The resin composition may further include any additives (F). Examples of any additives (F) include: hardening catalysts other than imidazole compounds; free radical polymerizable compounds; organometallic compounds such as organocopper compounds, organozinc compounds, and organocobalt compounds; colorants such as phthalocyanine blue, phthalocyanine green, iodine green, diazo yellow, crystal violet, titanium dioxide, and carbon black; polymerization inhibitors such as hydroquinone, catechol, pyrogallol, and phenothiazine; leveling agents such as organosilicon-based leveling agents and acrylic polymer-based leveling agents; thickeners such as bentonite and montmorillonite; defoamers such as organosilicon-based defoamers, acrylic defoamers, fluorine-based defoamers, and vinyl resin-based defoamers; ultraviolet absorbers such as benzotriazole-based ultraviolet absorbers; and adhesion improvers such as ureasilane. Triazole-based binding agents, tetraazole-based binding agents, triazine-based binding agents, and other binding agents; hindered phenolic antioxidants and other antioxidants; zirconia derivatives and other fluorescent whitening agents; fluorinated surfactants, organosilicon surfactants and other surfactants; phosphate ester dispersants, polyoxyethylene dispersants, alkyne dispersants, organosilicon dispersants, anionic dispersants, cationic dispersants and other dispersants; borate ester stabilizers, titanate stabilizers, aluminate stabilizers, zirconate stabilizers, isocyanate stabilizers, carboxylic acid stabilizers, carboxylic anhydride stabilizers and other stabilizers; tertiary amines and other photopolymerization initiators; pyrazoline derivatives, anthracene derivatives, coumarins, xanthanone derivatives, thioxanthone derivatives, and other photosensitizers. (F) Any additive may be used alone or in combination of two or more.

[0131] The resin composition may also include (G) a solvent as an arbitrary volatile component, in combination with the above-mentioned (A) imidazole compounds, (B) thermosetting resins, (C) inorganic fillers, (D) thermoplastic resins, (E) flame retardants, and (F) any additives. Organic solvents are typically used as (G) solvent. Examples of organic solvents include: ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; ester solvents such as methyl acetate, ethyl acetate, butyl acetate, isobutyl acetate, isoamyl acetate, methyl propionate, ethyl propionate, and γ-butyrolactone; ether solvents such as tetrahydropyran, tetrahydrofuran, 1,4-dioxane, diethyl ether, diisopropyl ether, dibutyl ether, diphenyl ether, and anisole; alcohol solvents such as methanol, ethanol, propanol, butanol, and ethylene glycol; and 2-ethoxyethyl acetate, propylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, and carbitol acetate. Ether ester solvents such as acetate (diethylene glycol monoethyl ether acetate), γ-butyrolactone, methyl methoxypropionate, etc.; ester alcohol solvents such as methyl lactate, ethyl lactate, methyl 2-hydroxyisobutyrate, etc.; ether alcohol solvents such as 2-methoxypropanol, 2-methoxyethanol, 2-ethoxyethanol, propylene glycol monomethyl ether, diethylene glycol monobutyl ether (butyl carbitol), etc.; acetylamine solvents such as N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, etc.; argonite solvents such as dimethyl sulfoxide; nitrile solvents such as acetonitrile, propionitrile, etc.; aliphatic hydrocarbon solvents such as hexane, cyclopentane, cyclohexane, methylcyclohexane, etc.; aromatic hydrocarbon solvents such as benzene, toluene, xylene, ethylbenzene, trimethylbenzene, etc. (G) Solvents can be used alone or in combination of two or more.

[0132] (G) The amount of solvent is not particularly limited. When all components in the resin composition are set to 100% by mass, it can be 60% or less by mass, 40% or less by mass, 30% or less by mass, 20% or less by mass, 15% or less by mass, 10% or less by mass, etc., or it can be 0% by mass.

[0133] From the perspective of thinner printed circuit boards, the thickness of the resin composition layer is preferably less than 100 μm, more preferably less than 80 μm, and even more preferably less than 50 μm. There is no particular limitation on the lower limit of the resin composition layer thickness; it can be greater than 5 μm, greater than 10 μm, etc.

[0134] -Manufacturing Method of Resin Sheets- There are no particular limitations on the manufacturing method of the resin sheet. For example, the resin sheet can be manufactured by coating a resin composition onto a release layer of a support. When using a liquid (varnish-like) resin composition, it can be directly coated onto the release layer of the support. Alternatively, a liquid (varnish-like) resin composition can be prepared by mixing a solvent with a non-volatile component of the resin composition and then coated onto the release layer. Examples of solvents include those described in (G) of the resin composition description. Furthermore, coating equipment such as a die coater can be used for coating.

[0135] The manufacturing method of resin sheets may, as needed, include drying the coated resin composition. Drying can be carried out using methods such as heating or blowing hot air. There are no particular limitations on the drying conditions, but drying is generally carried out when the solvent content in the resin composition layer is typically 10% by mass or less, preferably 5% by mass or less. Depending on the boiling point of the solvent in the resin composition, for example, when using a resin composition containing 30% to 60% by mass of solvent, a resin composition layer can be formed by drying at 50°C to 150°C for 3 to 10 minutes.

[0136] The method for manufacturing the resin sheet may further include any steps. For example, the method may include laminating a resin composition layer with a protective film selected according to the support. The thickness of the protective film is not particularly limited, for example, it is 1 μm to 40 μm. When the protective film is laminated, it is possible to prevent the adhesion of debris or damage to the surface of the resin composition layer. Usually, the protective film is removed in step (I) before the resin sheet is laminated with the inner substrate.

[0137] [Step (I): Lamination of resin sheet and inner substrate] One embodiment of the present invention relates to a method for manufacturing a printed wiring board, comprising step (I) of laminating a resin sheet onto an inner layer substrate in such a manner as bonding a resin composition layer to an inner layer substrate. The "inner layer substrate" used in step (I) refers to a component that becomes the substrate of the printed wiring board, and examples include glass epoxy substrates, metal substrates, polyester substrates, polyimide substrates, BT resin substrates, thermosetting polyphenylene ether substrates, etc. Furthermore, the substrate may have a conductor layer on one or both sides, and this conductor layer may be patterned. Sometimes, an inner layer substrate with a conductor layer (circuit) formed on one or both sides of the substrate is referred to as an "inner circuit substrate." Additionally, intermediate components for which an insulating layer and / or a conductor layer will be further formed during the manufacturing of the printed wiring board are also included in the aforementioned "inner layer substrate." When the printed wiring board is a component-integrated circuit board, an inner layer substrate with the component integrated can be used.

[0138] The lamination of the inner substrate and the resin sheet can be achieved, for example, by heat-pressing the resin sheet onto the inner substrate from the support side. Examples of components for heat-pressing the resin sheet onto the inner substrate (hereinafter also referred to as "heat-pressing components") include, for example, heated metal plates (SUS end plates, etc.) or metal rollers (SUS rollers, etc.). It should be noted that, preferably, the heat-pressing component is not pressed directly onto the resin sheet, but rather pressed using an elastic material such as heat-resistant rubber, so that the resin sheet fully follows the surface irregularities of the inner substrate.

[0139] The lamination of the inner substrate and the resin sheet can be carried out by vacuum lamination. In vacuum lamination, the heating and pressing temperature is preferably 60℃~160℃, more preferably 80℃~140℃; the heating and pressing pressure is preferably 0.098MPa~1.77MPa, more preferably 0.29MPa~1.47MPa; and the heating and pressing time is preferably 20 seconds~400 seconds, more preferably 30 seconds~300 seconds. Lamination is preferably carried out under reduced pressure conditions below 26.7 hPa.

[0140] Lamination can be performed using commercially available vacuum laminators. Examples of commercially available vacuum laminators include the vacuum pressure laminator manufactured by Meiki Seisakusho, the vacuum applicator manufactured by Nikko-Materials, and batch vacuum pressure laminators.

[0141] After lamination, the heated pressing member is pressed under normal pressure (atmospheric pressure), for example, from the support side, thereby performing a smoothing treatment on the laminated resin sheet. The pressing conditions for the smoothing treatment can be set to the same conditions as the heated pressing conditions for the lamination described above. The smoothing treatment can be performed using a commercially available laminator. It should be noted that lamination and smoothing treatment can be performed continuously using the aforementioned commercially available vacuum laminator.

[0142] [Step (II): Thermosetting of the resin composition layer] One embodiment of the present invention relates to a method for manufacturing a printed wiring board, comprising: step (II) after step (I), a step of thermally curing a resin composition layer in a nitrogen atmosphere. By thermally curing the resin composition layer, an insulating layer can be formed. The formed insulating layer comprises a cured resin composition, preferably only a cured resin composition.

[0143] The thermosetting of the resin composition layer in step (II) is carried out in a nitrogen atmosphere. Because the nitrogen atmosphere is filled with nitrogen, the oxygen concentration in the nitrogen atmosphere is low. The oxygen concentration in the nitrogen atmosphere is preferably below 5% by mass, more preferably below 3% by mass, particularly preferably below 1% by mass, and ideally 0% by mass.

[0144] The pressure conditions of the nitrogen atmosphere in step (II) can be atmospheric pressure or reduced pressure. In one example, the specific pressure conditions of the nitrogen atmosphere are preferably 0.075 mmHg (0.1 hPa) or higher, more preferably 1 mmHg (1.3 hPa) or higher, more preferably 3751 mmHg (5000 hPa) or lower, and more preferably 1875 mmHg (2500 hPa) or lower.

[0145] The thermosetting of the resin composition layer in step (II) includes the following sequence: (II-2) The resin composition layer is subjected to heat treatment at a temperature of T1, and (II-4) The resin composition layer is subjected to heat treatment at a temperature T2 that is higher than temperature T1. Hereinafter, the step of heat treatment at temperature T1 is sometimes referred to as the "pre-curing step (II-2)". In addition, the step of heat treatment at temperature T2 is sometimes referred to as the "post-curing step (II-4)".

[0146] Typically, prior to the pre-curing step (II-2), the resin composition layer is at a heating start temperature T0, which is lower than temperature T1. The heating start temperature T0 can be, for example, room temperature. Therefore, for step (II), a step (II-1) can be included prior to the pre-curing step (II-2) to heat the resin composition layer from the heating start temperature T0 to temperature T1. From the viewpoint of significantly obtaining the effects of the present invention, the heating rate in step (II-1) is preferably 0.5°C / min or more, more preferably 1°C / min or more, further preferably 1.5°C / min or more, further preferably 2°C / min or more, particularly preferably 2.5°C / min or more, preferably 30°C / min or less, more preferably 25°C / min or less, further preferably 20°C / min or less, further preferably 15°C / min or less, and particularly preferably 10°C / min or less. The heating rate in step (II-1) can be constant or variable.

[0147] In the pre-curing step (II-2), the resin composition layer is subjected to a heat treatment maintained at temperature T1. The heating temperature T1 in this pre-curing step (II-2) is set within a temperature range above room temperature and below temperature T2. From the viewpoint of significantly obtaining the effects of the present invention, the specific range of the heating temperature T1 is preferably 50°C or higher, more preferably 60°C or higher, further preferably 70°C or higher, particularly preferably 80°C or higher, preferably less than 150°C, more preferably less than 140°C, and further preferably less than 130°C. Maintaining the resin composition layer at temperature T1 in the pre-curing step (II-2) includes not only maintaining the temperature of the resin composition layer at a constant temperature, but also allowing the temperature of the resin composition layer to vary within a range that does not significantly impair the effects of the present invention. For example, in the pre-curing step (II-2), the temperature of the resin composition layer may also vary within a range of ±10°C, ±8°C, or ±5°C. However, it is preferable that even when the temperature of the resin composition layer changes in this way, the temperature of the resin composition layer in the pre-curing step (II-2) remains within the aforementioned preferred range, for example, between 50°C and 150°C. Particularly preferable, in the pre-curing step (II-2), is that the temperature of the resin composition layer remains constant and does not change.

[0148] In the pre-curing step (II-2), the range of time for which the resin composition layer is held at the heating temperature T1 depends on the composition of the resin composition and the value of the heating temperature T1. From the viewpoint of obtaining significant effects of the present invention, it is preferable to hold the resin composition layer for 10 minutes or more, more preferably for 15 minutes or more, particularly preferably for 20 minutes or more, preferably for 150 minutes or less, more preferably for 120 minutes or less, and particularly preferably for 120 minutes or less.

[0149] Typically, before the post-curing step (II-4), the resin composition layer is at a temperature lower than temperature T2. Therefore, step (II) may include a step (II-3) of heating the resin composition layer to temperature T2, after the pre-curing step (II-2) and before the post-curing step (II-4). From the viewpoint of significantly obtaining the effects of the present invention, the heating rate in step (II-3) is preferably 0.5°C / min or more, more preferably 1°C / min or more, further preferably 1.5°C / min or more, further preferably 2°C / min or more, particularly preferably 2.5°C / min or more, preferably 30°C / min or less, more preferably 25°C / min or less, further preferably 20°C / min or less, further preferably 15°C / min or less, and particularly preferably 10°C / min or less. The heating rate in step (II-3) may be constant or variable.

[0150] In the post-curing step (II-4), the resin composition layer is subjected to a heat treatment maintained at temperature T2. The heating temperature T2 in the post-curing step (II-4) is set to be higher than temperature T1. From the viewpoint of significantly obtaining the effects of the present invention, the specific range of the heating temperature T2 is preferably 150°C or higher, more preferably 155°C or higher, further preferably 160°C or higher, particularly preferably 170°C or higher, preferably 250°C or lower, more preferably 230°C or lower, further preferably 220°C or lower, further preferably 210°C or lower, and particularly preferably 200°C or lower. Maintaining the resin composition layer at temperature T2 in the post-curing step (II-4) includes not only maintaining the temperature of the resin composition layer at a constant temperature, but also allowing the temperature of the resin composition layer to vary within a range that does not significantly impair the effects of the present invention. For example, in the post-curing step (II-4), the temperature of the resin composition layer may also vary within a range of ±10°C, ±8°C, or ±5°C. However, it is preferable that even when the temperature of the resin composition layer changes in this way, the temperature of the resin composition layer in the post-curing step (II-4) remains within the aforementioned preferred range, for example, between 150°C and 250°C. Particularly preferable is that the temperature of the resin composition layer remains constant in the post-curing step (II-4).

[0151] From the viewpoint of achieving significant effects of the present invention, the difference T2-T1 between the heating temperature T2 in the post-curing step (II-4) and the heating temperature T1 in the pre-curing step (II-2) is preferably within a specific range. Specifically, the aforementioned difference T2-T1 is preferably 20°C or more, more preferably 30°C or more, particularly preferably 40°C or more, preferably 150°C or less, more preferably 140°C or less, further preferably 130°C or less, and particularly preferably 120°C or less. In the event of temperature changes in the resin composition layer during the pre-curing step (II-2) and / or the post-curing step (II-4), the difference between the median temperature of the resin composition in the post-curing step (II-4) and the median temperature of the resin composition in the pre-curing step (II-2) is preferably within the aforementioned range.

[0152] In the post-curing step (II-4), the range of time for which the resin composition layer is held at the heating temperature T2 depends on the composition of the resin composition and the value of the heating temperature T2, but from the viewpoint of obtaining significant effects of the present invention, it is preferable to hold for 10 minutes or more, more preferably 15 minutes or more, particularly preferably 20 minutes or more, preferably 150 minutes or less, and more preferably 120 minutes or less.

[0153] After the heat treatment at temperature T1 in the pre-curing step (II-2), the resin composition layer can be temporarily cooled before the heat treatment at temperature T2 in the post-curing step (II-4) is performed. Alternatively, after the heat treatment at temperature T1 in the pre-curing step (II-2), the resin composition layer can be left uncooled, and the heat treatment at temperature T2 in the pre-curing step (II-4) can be performed.

[0154] The heat treatment in the pre-curing step (II-2) and the heat treatment in the post-curing step (II-4) can be performed using the same heat treatment apparatus. Alternatively, the heat treatment in the pre-curing step (II-2) can be performed using a first heat treatment apparatus, and the heat treatment in the post-curing step (II-4) can be performed using a second heat treatment apparatus different from the first heat treatment apparatus. There are no particular limitations on the heat treatment apparatus as long as it can thermally cure the resin composition layer. Examples of heat treatment apparatus include, for instance, an oven and a hot press. For example, after performing the heat treatment in the pre-curing step (II-2) using an oven set to temperature T1, the inner layer substrate and resin sheet can be transferred to an oven set to temperature T2 for the heat treatment in the post-curing step (II-4). Alternatively, a heat treatment apparatus capable of temperature control can be used to perform the heat treatment in the pre-curing step (II-2), and then the temperature can be increased from temperature T1 to temperature T2 for the heat treatment in the post-curing step (II-4).

[0155] Step (II) may also be combined with steps (II-1) to (II-4) above to further include any additional steps. For example, step (II) may also include a step of performing a heat treatment on the resin composition layer at a heating temperature other than the aforementioned temperatures T1 and T2. That is, step (II) is not limited to two heat treatment steps, but may include three or more heat treatment steps.

[0156] [Step (III): Peeling off the support] One embodiment of the present invention relates to a method for manufacturing a printed circuit board, comprising a step (III) of peeling off the support body after step (II). According to this embodiment, adhesion between the support body and the insulating layer, which is a hardened resin composition layer, can be suppressed. Therefore, poor peeling can be suppressed, thereby enabling smooth peeling of the support body.

[0157] Typically, peeling is performed by stretching the support relative to the insulating layer, thereby removing the support. For example, the insulating layer and inner substrate can be transported while the support is fixed, and the support can be peeled off. Alternatively, the support can be stretched while the insulating layer and inner substrate are fixed, and the support can be peeled off. Furthermore, the support can be stretched while transporting the insulating layer and inner substrate, and the support can be peeled off.

[0158] Typically, the support is peeled off by stretching it relative to the surface of the insulating layer along a peeling direction that forms a specific angle with respect to the surface of the insulating layer. There is no particular limitation on the range of the angle formed by the peeling direction relative to the surface of the insulating layer. From the viewpoint of smoothly peeling off the support, the aforementioned angle range is preferably 0° or more, preferably 70° or less, more preferably 60° or less, further preferably 50° or less, further preferably 40° or less, further preferably 30° or less, further preferably 20° or less, and particularly preferably 10° or less.

[0159] There are no particular limitations on the temperature conditions for peeling off the support. From the viewpoint of reducing the energy required to manufacture the printed circuit board, the peeling off of the support is usually performed at room temperature or close to room temperature. Therefore, the inner substrate, insulating layer and support are usually cooled after the aforementioned step (II), and then the support is peeled off. The specific temperature range for peeling off the support is preferably 10°C or higher and 40°C or lower. In addition, there are no particular limitations on the cooling rate in the cooling step from temperature T2, but it is preferably 0.5°C / min or higher, more preferably 1°C / min or higher, further preferably 1.5°C / min or higher, further preferably 2°C / min or higher, particularly preferably 2.5°C / min or higher, preferably 30°C / min or lower, more preferably 25°C / min or lower, further preferably 20°C / min or lower, further preferably 15°C / min or lower, and particularly preferably 10°C / min or lower.

[0160] In the manufacturing method of the printed circuit board according to this embodiment, poor peeling between the insulation layer and the support is suppressed, thus accelerating the peeling speed of the support. From the viewpoint of improving the production speed of the printed circuit board, a fast peeling speed is preferable. Specifically, the peeling speed is preferably 1 m / min or more, more preferably 2 m / min or more, further preferably 3 m / min or more, even more preferably 4 m / min or more, and particularly preferably 5 m / min or more. There is no particular upper limit, for example, it can be 20 m / min or less, 10 m / min or less, etc.

[0161] [Step (IV): Opening the hole] The method for manufacturing a printed wiring board according to one embodiment of the present invention may further include any steps. For example, the method for manufacturing a printed wiring board according to this embodiment may also include a step (IV) of opening holes in the insulating layer. This step (IV) may be performed before or after step (III).

[0162] Step (IV) involves forming vias or through-holes in the insulating layer. The formation of the vias can be carried out using, for example, a drill bit, laser, or plasma, depending on the composition of the resin composition used in the formation of the insulating layer. The size and shape of the vias can be appropriately determined according to the design of the printed circuit board.

[0163] [Step (V): Roughening] One embodiment of the present invention relates to a method for manufacturing a printed circuit board, which may include a step (V) of roughening an insulating layer. This step (V) is typically performed after step (III), but may also be performed before step (III). Alternatively, step (V) is preferably performed after step (IV). For example, in step (IV), a hole may be formed in the insulating layer, and after performing the roughening step (V), the step (III) of peeling off the support may be performed. When step (V) is performed after the hole is formed in step (IV), resin residue (smear) that may remain in the hole can be removed.

[0164] There are no particular restrictions on the steps and conditions of the roughening treatment, and known steps and conditions used in forming the insulating layer of a printed wiring board can be adopted. For example, the insulating layer can be roughened by sequentially performing a swelling treatment based on a swelling solution, a roughening treatment based on an oxidant, and a neutralization treatment based on a neutralizing solution.

[0165] Examples of swelling solutions used in roughening treatment include alkali solutions and surfactant solutions, with alkali solutions being preferred. Sodium hydroxide solutions and potassium hydroxide solutions are particularly desirable as alkali solutions. Commercially available swelling solutions include, for example, "Swelling Dip Securiganth P" and "Swelling Dip Securiganth SBU" manufactured by ATOTECH JAPAN. Swelling treatment based on the swelling solution can be performed, for example, by immersing the insulating layer in a swelling solution at 30°C to 90°C for 1 to 20 minutes. From the viewpoint of suppressing the swelling of the resin in the insulating layer to a suitable level, it is preferable to immerse the insulating layer in a swelling solution at 40°C to 80°C for 5 to 15 minutes.

[0166] Examples of oxidants used in roughening treatments include alkaline permanganate solutions, such as potassium permanganate or sodium permanganate dissolved in an aqueous solution of sodium hydroxide. Roughening treatment based on oxidants such as alkaline permanganate solutions is preferably performed by immersing the insulating layer in an oxidant solution heated to 60°C to 100°C for 10 to 30 minutes. Furthermore, the concentration of permanganate in the alkaline permanganate solution is preferably 5% to 10% by mass. Commercially available oxidants include alkaline permanganate solutions such as "Concentrate Compact CP" and "Dosing Solution Securiganth P" manufactured by Ammet Japan Co., Ltd.

[0167] The neutralizing solution used in the roughening treatment is preferably an acidic aqueous solution. Commercially available examples include "Reduction Solution Securiganth P" manufactured by Ammet Japan Co., Ltd. The treatment based on the neutralizing solution can be performed by immersing the surface that has undergone oxidant-based roughening treatment in a neutralizing solution at 30°C to 80°C for 5 to 30 minutes. From an operability perspective, it is preferable to immerse the object that has undergone oxidant-based roughening treatment in a neutralizing solution at 40°C to 70°C for 5 to 20 minutes.

[0168] In one example, the arithmetic mean roughness (Ra) of the surface of the roughened insulating layer is preferably below 500 nm, more preferably below 400 nm, and even more preferably below 300 nm. There is no particular limitation on the lower limit; for example, it can be above 1 nm, above 2 nm, etc. Furthermore, the root mean square roughness (Rq) of the surface of the roughened insulating layer is preferably below 500 nm, more preferably below 400 nm, and even more preferably below 300 nm. There is no particular limitation on the lower limit; for example, it can be above 1 nm, above 2 nm, etc. The arithmetic mean roughness (Ra) and root mean square roughness (Rq) of the insulating layer surface can be measured using a non-contact surface roughness meter.

[0169] [Step (VI): Formation of the conductor layer] One embodiment of the present invention relates to a method for manufacturing a printed wiring board, which may also include a step (VI) of forming a conductor layer. In this step (VI), the conductor layer is typically formed on an insulating layer. Therefore, step (VI) is usually performed after step (III). In a preferred embodiment, steps (IV), (V), and (VI) are performed sequentially.

[0170] There are no particular limitations on the conductor material used in the conductor layer. In a suitable embodiment, the conductor layer comprises one or more metals selected from the group consisting of gold, platinum, palladium, silver, copper, aluminum, cobalt, chromium, zinc, nickel, titanium, tungsten, iron, tin, and indium. The conductor layer can be a single metal layer or an alloy layer. Examples of alloy layers include layers formed from alloys of two or more metals selected from the above group (e.g., nickel-chromium alloys, copper-nickel alloys, and copper-titanium alloys). From the viewpoints of versatility, cost, and ease of patterning in conductor layer formation, it is preferable to have a single metal layer of chromium, nickel, titanium, aluminum, zinc, gold, palladium, silver, or copper, or an alloy layer of nickel-chromium alloy, copper-nickel alloy, or copper-titanium alloy. More preferably, it is a single metal layer of chromium, nickel, titanium, aluminum, zinc, gold, palladium, silver, or copper, or an alloy layer of nickel-chromium alloy. It is even more preferable to have a single metal layer of copper.

[0171] The conductor layer can be a single-layer structure or a multi-layer structure consisting of two or more single-metal or alloy layers made of different types of metals or alloys. When the conductor layer is a multi-layer structure, the layer in contact with the insulating layer is preferably a single-metal layer of chromium, zinc, or titanium, or an alloy layer of nickel-chromium alloy.

[0172] The thickness of the conductor layer depends on the desired design of the printed wiring board, typically 3μm to 35μm, preferably 5μm to 30μm.

[0173] The conductor layer can be formed, for example, by plating. Specifically, known techniques such as semi-additive and fully additive methods can be used to plate the surface of the insulating layer to form a conductor layer with the desired wiring pattern. From the viewpoint of ease of manufacturing, the semi-additive method is preferred. The following shows an example of forming a conductor layer using the semi-additive method.

[0174] First, a seed layer is formed on the surface of an insulating layer using electroless plating. Next, corresponding to the desired wiring pattern, a mask pattern is formed on the formed seed layer, exposing a portion of the seed layer. A metal layer is formed on the exposed seed layer using electrolytic plating, and then the mask pattern is removed. Finally, the unwanted seed layer is removed using etching or similar methods, thus forming a conductor layer with the desired wiring pattern.

[0175] As needed, steps (I) to (VI) can be repeated to form the insulating and conductor layers to manufacture a multilayer printed wiring board.

[0176] [Other steps] One embodiment of the present invention relates to a method for manufacturing a printed wiring board, which may be combined with the above steps to further include any additional steps.

[0177] For example, there are cases where a long strip of resin sheet is continuously transported along its length. In this case, the resin sheet is typically drawn from a roll and fed onto an inner layer substrate. In this case, the method for manufacturing the printed circuit board may also include a step of cutting the long strip of resin sheet into appropriate sizes. The cutting of the resin sheet may be performed before or after step (I).

[0178] For example, there are cases where resin sheets with a protective film covering the resin composition layer are used. The protective film is typically located on the side of the resin composition layer opposite to the support. In this case, the method for manufacturing the printed circuit board may also include a step of removing the protective film. Typically, the removal of the protective film is performed before step (I).

[0179] Applications of printed circuit boards The printed wiring board manufactured using the manufacturing method according to one embodiment of the present invention can be used for a wide range of applications, such as semiconductor devices. These semiconductor devices include the aforementioned printed wiring board. Specific examples of semiconductor devices include various semiconductor devices used in electrical products (e.g., computers, mobile phones, digital cameras, and televisions) and vehicles (e.g., motorcycles, automobiles, trams, ships, and aircraft). However, the printed wiring board can also be used for applications other than those described above. [Example]

[0180] Hereinafter, embodiments of the present invention will be shown to illustrate the invention in detail. However, the present invention is not limited to the following embodiments. In the following description, unless otherwise expressly stated, "parts" and "%" refer to "parts by mass" and "% by mass," respectively. Furthermore, unless otherwise expressly stated, the operations described below are performed in an atmospheric environment at normal temperature and pressure (25°C, 1 atm).

[0181] <Manufacturing Example 1: Manufacturing of Support 1 with an Acrylic Resin Release Layer> (Manufacturing of acrylic resin (A1)) In a temperature-controlled reactor equipped with a stirrer, thermometer, and condenser, 500 parts by mass of toluene, 80 parts by mass of stearate methacrylate (18 carbon atoms in the alkyl chain), 15 parts by mass of methacrylic acid, 5 parts by mass of 2-hydroxyethyl methacrylate, and 1 part by mass of azobisisobutyronitrile were added dropwise over 4 hours at a reaction temperature of 85°C to carry out a polymerization reaction. The reaction was then cured at the same temperature for 2 hours to terminate the reaction, yielding an acrylic resin (A). This acrylic resin (A) was dissolved in water containing 5% by mass of isopropanol and 5% by mass of n-butyl solvent to obtain a resin solution containing an acrylic resin (A1) as a release compound.

[0182] (Preparation of acrylic resin (B1)) In a stainless steel reaction vessel, methyl methacrylate (a), hydroxyethyl methacrylate (b), and aromatic amino carbamate acrylate oligomer (Daicel-Allnex "EBECRYL 220", with 6 acrylonitrile groups) (c) were loaded at a mass ratio of (a) / (b) / (c) = 94 / 1 / 5. Then, sodium dodecylbenzenesulfonate as an emulsifier was added to the aforementioned reaction vessel in a mass ratio of 2 parts by mass relative to a total of 100 parts by mass of (a)+(b)+(c), and the mixture was stirred to prepare a mixture (1).

[0183] Next, a reaction apparatus equipped with a stirrer, a reflux condenser, a thermometer, and a dropping funnel was prepared. 60 parts by mass of the above mixture (1), 200 parts by mass of isopropanol, and 5 parts by mass of potassium persulfate as a polymerization initiator were added to the reaction apparatus and heated to 60°C to prepare mixture (2). Mixture (2) was kept at 60°C for 20 minutes.

[0184] Next, a mixture (3) was prepared, consisting of 40 parts by mass of mixture (1), 50 parts by mass of isopropanol, and 5 parts by mass of potassium persulfate. The mixture (3) was added dropwise to mixture (2) over 2 hours using a dropping funnel to prepare mixture (4).

[0185] Then, the mixture (4) was kept at 60°C for 2 hours. After cooling the resulting mixture (4) to below 50°C, it was transferred to a container equipped with a stirrer and a vacuum distillation device. 60 parts by weight of 25% ammonia and 900 parts by weight of pure water were added to the container, and isopropanol and unreacted monomers were recovered under reduced pressure while heating to 60°C to obtain a composition containing an acrylic resin (B1) as any resin dispersed in pure water.

[0186] (Preparation of release agent (1)) A resin solution containing acrylic resin (A1) and a composition containing acrylic resin (B1) are mixed in such a way that the mass ratio of acrylic resin (A1) to acrylic resin (B1) is (A1) / (B1) = 20 / 80, to obtain an intermediate composition. Then, a fluorinated surfactant (PLASCOAT RY-2, manufactured by Koyo Chemical Industry Co., Ltd.) is added to this intermediate composition in a manner that is 0.1 parts by mass relative to all 100 parts by mass of the aforementioned intermediate composition, to obtain a liquid mold release agent (1) as part of the acrylic resin composition.

[0187] (Manufacturing of Support 1) A PET film (Toray Industries "T60" (38 μm thick)) was prepared as the support substrate. A release agent (1) was applied to one side of the support substrate using a gravure coating machine and dried to form a release layer with a thickness of 0.1 μm. Through the above operations, a support body 1 with a support substrate and a release layer containing acrylic resin was obtained.

[0188] <Manufacturing Example 2: Manufacturing of Support 2 with a Release Layer Free of Acrylic Resin> (Preparation of polyolefin resin (C1)) In a four-necked flask, 280 g of a propylene-ethylene copolymer (propylene / ethylene = 99 / 1 (mass ratio)) was heated and melted under a nitrogen atmosphere. Then, the temperature was maintained at 170°C, and 5.5 g of dicumyl peroxide, acting as a free radical generator, was added over 1 hour with stirring. The reaction was then allowed to proceed for 1 hour. After the reaction was complete, the resulting product was added to a large amount of acetone to precipitate the resin. The resin was then washed several times with acetone to remove unreacted monomers. Finally, the resin was dried under reduced pressure in a vacuum dryer to obtain a polyolefin resin (C1).

[0189] (Preparation of aqueous dispersions of polyolefin resin (C1)) Prepare a stirrer equipped with a heater and a 1-liter pressure-resistant glass container capable of being sealed. In the glass container of this stirrer, add 60g of polyolefin resin (C1), 45.0g of ethylene glycol-n-butyl ether (boiling point 171℃), and 188.1g of distilled water. Stir at 300 rpm. After 10 minutes, heat to maintain the system temperature at 140℃ and stir for 60 minutes. Then, cool to room temperature (approximately 25℃) by air cooling while maintaining stirring at 300 rpm. Filter the contents of the glass container under pressure (0.2MPa air pressure) using a 300-mesh stainless steel filter (0.035mm wire diameter, plain weave) to obtain an aqueous dispersion of polyolefin resin (C1) (non-volatile component concentration 25% by mass).

[0190] (Preparation of release agent (2)) A water-based dispersion of polyolefin resin (C1) with 100 parts by weight (based on non-volatile components) and a polyvinyl alcohol aqueous solution ("JT-05" manufactured by VAM & POVAL Co., Ltd. of Japan, with a saponification rate of 94.5%, a degree of polymerization of 500, and a non-volatile component concentration of 8% by weight) with 300 parts by weight (based on non-volatile components) were mixed. Water was then added to adjust the final non-volatile component concentration to 6.0% by weight, resulting in a liquid release agent (2) as a component of polyolefin resin.

[0191] (Manufacturing of Support 2) As the support substrate, a PET film (Toray Industries "T60" (thickness 38μm)) was prepared. A release agent (2) was applied to one side of this support substrate using a gravure coating machine and dried to form a release layer with a thickness of 0.1μm. Through the above operations, a support body 2 with a support substrate and a release layer free of acrylic resin was obtained.

[0192] <Manufacturing Example 3: Manufacturing of Resin Varnish A1> While stirring, 6 parts of bisphenol-type epoxy resin (Nippon Steel & Sumitomo Chemical Co., Ltd. "ZX1059", epoxy equivalent approximately 169 g / eq., a 1:1 mixture of bisphenol A and bisphenol F), 9 parts of bixylenol-type epoxy resin (Mitsubishi Chemical Co., Ltd. "YX4000HK", epoxy equivalent approximately 185 g / eq.), 21 parts of biphenyl-type epoxy resin (Nippon Kayaku Co., Ltd. "NC3000L", epoxy equivalent 288 g / eq.), and 10 parts of phenoxy resin (Mitsubishi Chemical Co., Ltd. "YX7553BH30", a 1:1 solution of cyclohexanone and methyl ethyl ketone (MEK) with 30% by mass of non-volatile components) were heated and dissolved in a mixed solvent of 20 parts naphtha and 5 parts cyclohexanone to obtain a mixture. After cooling to room temperature, add 6 parts of a cresol-phenolic varnish hardener containing a triazine skeleton (hydroxyl equivalent 151 g / eq., DIC's "LA-3018-50P", 50% non-volatile component in 2-methoxypropanol solution) and an active ester hardener (DIC's "HPC-8000-65T", weight average molecular weight approximately 2700, active group equivalent approximately 223 g / eq., 65% by mass of non-volatile component). The mixture was prepared by uniformly dispersing 20 parts of toluene solution, 2 parts of imidazole-based curing accelerator (1-benzyl-2-phenylimidazolium manufactured by Shikoku Chemical Co., Ltd., MEK solution with 5% by mass of non-volatile components), 2 parts of flame retardant (HCA-HQ manufactured by Sanko Co., Ltd., 10-(2,5-dihydroxyphenyl)-10-hydro-9-oxa-10-phosphaphenanthrene-10-oxide, average particle size 2 μm), and 170 parts of inorganic filler material using a high-speed rotary mixer. The mixture was then filtered through a cartridge filter (SHP050 manufactured by ROKITECHNO Co., Ltd.) to prepare resin varnish A1. As the inorganic filler material, spherical silica (SOC2 manufactured by Yaduma Co., Ltd., average particle size 0.5 μm, specific surface area 5.8 m² / g) surface-treated with an aminosilane coupling agent (KBM573 manufactured by Shin-Etsu Chemical Co., Ltd.) was used.

[0193] <Manufacturing Example 4: Manufacturing of Resin Varnish A2> While stirring, 30 parts of biphenyl-type epoxy resin (epoxy equivalent approximately 290 g / eq., manufactured by Nippon Kayaku Co., Ltd., "NC3000H"), 5 parts of naphthalene-type tetrafunctional epoxy resin (epoxy equivalent 162 g / eq., manufactured by DIC, "HP-4700"), 15 parts of liquid bisphenol A-type epoxy resin (epoxy equivalent 180 g / eq., manufactured by Mitsubishi Chemical Co., Ltd., "jER828EL"), and 2 parts of phenoxy resin (weight average molecular weight 35000, manufactured by Mitsubishi Chemical Co., Ltd., "YX7553BH30", methyl ethyl ketone (MEK) solution with 30% by mass of non-volatile components) were heated and dissolved in a mixed solvent of 8 parts MEK and 8 parts cyclohexanone to obtain a mixture. To prepare resin varnish A2, 32 parts of a phenolic varnish hardener containing a triazine skeleton (phenolic hydroxyl equivalent of approximately 124 g / eq., DIC Corporation's "LA-7054", a MEK solution with 60% by mass of non-volatile components) and 2 parts of an imidazole-based hardening accelerator (Shikoku Chemical Co., Ltd.'s "1-benzyl-2-phenylimidazolium", a MEK solution with 5% by mass of non-volatile components) were mixed, along with 160 parts of inorganic filler and 2 parts of a polyvinyl butyral resin solution (weight average molecular weight 27,000, glass transition temperature 105°C, Sekisui Chemicals Co., Ltd.'s "KS-1", a mixed solution of ethanol and toluene with 15% by mass of non-volatile components in a 1:1 mass ratio) were uniformly dispersed using a high-speed rotary mixer. As an inorganic filler material, spherical silica (SOC2, manufactured by Artuma Corporation, with an average particle size of 0.5 μm and a specific surface area of ​​5.8 m² / g) that has been surface-treated with an aminosilane coupling agent ("KBM573" manufactured by Shin-Etsu Chemical Co., Ltd.) is used.

[0194] <Manufacturing Example 5: Manufacturing of Resin Varnish B1> Except for replacing 2 parts of the imidazole-based curing accelerator (1-benzyl-2-phenylimidazolium manufactured by Shikoku Kasei Corporation, a MEK solution with 5% by mass of non-volatile components) with 2 parts of the phosphorus-based curing accelerator (Tetrabutylphosphonium decanoate manufactured by Hokuko Chemical Industry Co., Ltd., a MEK solution with 5% by mass of non-volatile components), the resin varnish B1 was prepared using the same method as in Manufacturing Example 3.

[0195] [Example 1] (Manufacturing of resin sheets) Resin varnish A1 was uniformly applied to the release layer side of the support 1 obtained in Manufacturing Example 1 using a die coater, and dried at 80°C to 120°C (average 100°C) for 6 minutes to obtain a resin sheet having a support substrate, a release layer, and a resin composition layer in sequence. The thickness of the resin composition layer of the resin sheet was 40 μm.

[0196] (Lamination of resin sheet onto the inner circuit board) A glass cloth substrate epoxy resin double-sided copper-clad laminate (copper foil thickness 18μm, substrate thickness 0.8mm, Panasonic Electric Works "R1515A") was immersed in an etchant (MEC "CZ8100") to roughen the copper surface, resulting in an inner layer circuit board. Resin sheets were then laminated onto both sides of this inner layer circuit board using an intermittent vacuum pressure laminator (Nichigo-Morton, 2-Stage Buildup Laminator "CVP700"). This lamination was performed by bonding the resin composition layer of the resin sheet to the inner layer circuit board. Furthermore, this lamination was performed by: depressurizing for 30 seconds, adjusting the pressure to below 13 hPa, and then pressing under pressure conditions of 100°C, 0.74 MPa, and 30 seconds. Through the aforementioned lamination, a sample laminate containing a support, a resin composition layer, an inner circuit board, a resin composition layer, and a support is obtained in sequence.

[0197] (Curing of the resin composition layer) After laminating the resin composition layer and the inner circuit board, the sample laminate, with the support attached, was placed in a nitrogen oven. After placement, the door was closed, and nitrogen was allowed to circulate until the oxygen concentration inside the oven reached 0.5%. Once the oxygen concentration in the oven was confirmed to be 0.5%, the resin composition layer was heat-cured under the following curing conditions. Specifically, in the curing conditions of Example 1, the oven temperature was increased from 30°C to 130°C at a rate of 10°C / min, and then heat-cured at 130°C for 30 minutes. The temperature was then increased to 170°C at a rate of 10°C / min, and then heat-cured at 170°C for 30 minutes. Then, the temperature was decreased to 30°C at a rate of 5°C / min, and the sample laminate was removed from the nitrogen oven. The resin composition layer heat-cured to form an insulating layer, thus obtaining an evaluation sample sequentially comprising a support, an insulating layer, an inner circuit board, an insulating layer, and a support. The thickness of the insulating layer on the inner circuit was 40 μm.

[0198] (Stripping of the support) The evaluation sample was cooled to room temperature (approximately 25°C), and then the support was peeled off. Peeling was successful; the support and insulation layer were peeled off without damage. The result of the peeling was a printed wiring board with an insulation layer and a support peeled off from the aforementioned insulation layer.

[0199] [Example 2] Except for changing resin varnish A1 to resin varnish A2, the resin sheet, evaluation sample, and printed wiring board were manufactured in the same manner as in Example 1. During the peeling step, peeling was successful, and the support and insulation layer were peeled off without damage.

[0200] [Comparative Example 1] Except for altering the curing conditions in the steps of thermosetting the resin composition layer as described below, the resin sheet and evaluation sample were manufactured in the same manner as in Example 1. In the curing conditions of Comparative Example 1, after confirming that the oxygen concentration in the oven was 0.5%, the oven temperature was increased from 30°C to 200°C at a rate of 10°C / min, and then thermoset at 200°C for 90 minutes. Then, the temperature was decreased to 30°C at a rate of 5°C / min, and the sample laminate was removed from the nitrogen oven to obtain the evaluation sample.

[0201] The evaluation sample was cooled to room temperature (approximately 25°C), and then an attempt was made to peel off the support. However, the insulation layer adhered to the support, making peeling difficult. Furthermore, a forced peel was attempted, resulting in damage to the support.

[0202] [Comparative Example 2] Except that resin varnish A1 was changed to resin varnish A2, resin sheets and evaluation samples were manufactured in the same manner as in Comparative Example 1. The evaluation samples were cooled to room temperature (approximately 25°C), and then an attempt was made to peel off the support. However, the insulation layer adhered to the support, making peeling difficult. Furthermore, peeling was attempted with difficulty, resulting in the destruction of the support.

[0203] [Reference Example 1] Except that resin varnish A1 was changed to resin varnish B, resin sheets and evaluation samples were manufactured in the same manner as in Comparative Example 1. The evaluation samples were cooled to room temperature (approximately 25°C), and then the support was peeled off. The peeling performance was good, and the support and insulation layer were peeled off without damage. As a result of the peeling, a printed wiring board with an insulation layer and a support peeled off from the aforementioned insulation layer were obtained.

[0204] [Reference Example 2] Except that support 1 was changed to support 2, resin sheets and evaluation samples were manufactured in the same manner as in Comparative Example 1. The evaluation samples were cooled to room temperature (approximately 25°C), and then the support was peeled off. The peeling was successful, and the support and insulation layer were peeled off without damage. As a result of the peeling, a printed wiring board with an insulation layer and a support peeled off from the aforementioned insulation layer were obtained.

[0205] [Reference Example 3] Except that the support 1 was replaced with a PET film (Toyobo Co., Ltd. "E7004", thickness 38 μm) with an organosilicon release layer, resin sheets and evaluation samples were manufactured in the same manner as in Comparative Example 1. The evaluation samples were cooled to room temperature (approximately 25°C), and then the support was peeled off. The peeling performance was good, and the support and the insulating layer were peeled off without damage. As a result of the peeling, a printed wiring board with an insulating layer and a support peeled off from the aforementioned insulating layer were obtained.

[0206] [Reference Example 4] After placing the sample laminate into a nitrogen oven, the resin composition layers were thermo-cured in an air atmosphere without nitrogen recirculation. Otherwise, resin sheets and evaluation samples were manufactured in the same manner as in Comparative Example 1. The evaluation samples were cooled to room temperature (approximately 25°C), and then the support was peeled off. Peeling was successful; the support and insulation layer were peeled off without damage. As a result of the peeling, a printed circuit board with an insulation layer and a support peeled off from the aforementioned insulation layer were obtained.

[0207] [result] The results of the foregoing embodiments, comparative examples, and reference examples are shown in the following table. The abbreviations in the "Determination" section of the following table have the following meanings: "OK": The support and insulation layer are undamaged, and the support can be peeled off. “NG”: Poor peeling results in damage to the support or insulation layer.

[0208] [Table 1. Results of the Examples, Comparative Examples, and Reference Examples] Release agent resin composition atmosphere T1 (°C) T2 (°C) determination Example 1 acrylic A1 (containing imidazole compounds) Nitrogen 130 170 OK Example 2 acrylic A2 (containing imidazole compounds) Nitrogen 130 170 OK Comparative Example 1 acrylic A1 (containing imidazole compounds) Nitrogen - 200 NG Comparative Example 2 acrylic A2 (containing imidazole compounds) Nitrogen - 200 NG Reference Example 1 acrylic B (excluding imidazole compounds) Nitrogen - 200 OK See Example 2 Polyolefin A1 (containing imidazole compounds) Nitrogen - 200 OK See Example 3 Organosilicon A1 (containing imidazole compounds) Nitrogen - 200 OK See Example 4 acrylic A1 (containing imidazole compounds) Air - 200 OK .

[0209] [discuss] The results of Comparative Examples 1 and 2 show that, conventionally, poor peeling occurs between the support and the resin composition layer. Furthermore, the results of Reference Examples 1-4 show that the aforementioned poor peeling is a particular (specific) problem that arises when all conditions are met: the release agent contains a (meth)acrylic resin, the resin composition layer contains a resin composition containing an imidazole compound, and thermosetting is performed in a nitrogen atmosphere. Based on Examples 1 and 2, it has been confirmed that the aforementioned specific problem can be solved by the manufacturing method of the present invention.

Claims

1. A method for manufacturing a printed wiring board, the method comprising, in sequence: (I) a step of laminating a resin sheet onto an inner layer substrate in such a manner as bonding a resin composition layer to an inner layer substrate, wherein the resin sheet comprises: a support having a release layer, and a resin composition layer formed on the release layer of the support; (II) a step of thermosetting the resin composition layer in a nitrogen atmosphere; and (III) a step of peeling off the support, wherein, The release layer comprises (meth)acrylic resin, the resin composition layer comprises a resin composition comprising an imidazole compound, and the thermosetting of the resin composition layer comprises, in sequence, a heat treatment of the resin composition layer at a temperature T1 and a heat treatment of the resin composition layer at a temperature T2 higher than T1.

2. The method for manufacturing a printed circuit board as described in claim 1, wherein, The resin composition includes thermosetting resin.

3. The method for manufacturing a printed circuit board as described in claim 2, wherein, Thermosetting resins include one or more selected from epoxy resins, phenolic resins, reactive ester resins, carbodiimide resins, acid anhydride resins, amine resins, benzoxazine resins, cyanate ester resins, and thiol resins.

4. The method for manufacturing a printed circuit board as described in claim 1, wherein, Temperature T2 is above 150℃.

5. The method for manufacturing a printed circuit board as described in claim 1, wherein, The temperature difference between T2 and T1, T2-T1, is greater than 20℃.

6. A method for manufacturing a printed circuit board as described in claim 1, wherein, Temperature T1 is above 50℃.

7. The method for manufacturing a printed circuit board as described in claim 1, wherein, Step (II) includes heating the resin composition layer to temperature T2 at a heating rate of more than 0.5°C / min and less than 30°C / min.