Photo-curable thermosetting resin composition, dry film, cured product, and electronic component having the cured product

Abstract

To provide a photocurable and thermosetting resin composition which is excellent in storage stability, suppresses defects such as pinholes and cissing in an obtained dry film, and is excellent in electrical characteristics, a cured product thereof, and an electronic component having the cured product.SOLUTION: The photocurable and thermosetting resin composition comprises (A) an epoxy resin, (B) a carboxyl group-containing resin, (C) a photopolymerization initiator, (D) a photosensitive monomer, (E) silica, (F) barium sulfate and an organic solvent, and is composed of at least two liquid resin compositions to obtain the photocurable and thermosetting resin composition. The photocurable and thermosetting resin composition is characterized in that (B) a carboxyl group-containing resin, (D) a photosensitive monomer and (E) silica are contained in a resin composition different from (A) an epoxy resin, (F) barium sulfate and (C) a photopolymerization initiator, and the resin composition containing (C) the photopolymerization initiator contains an organic solvent capable of dissolving (C) the photopolymerization initiator.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a photocurable thermosetting resin composition, a dry film, a cured product, and an electronic component having the cured product. In particular, the present invention relates to a photocurable thermosetting resin composition consisting of at least two components, a cured product thereof suitable for printed wiring boards, such as a solder resist, and an electronic component having the cured product. [Background technology]

[0002] Conventionally, solder resists have been used in printed wiring boards as protective materials for wiring board circuits, and high solder heat resistance and electrical insulation properties are required. An example of such a material composition is an alkali-developable photocurable thermosetting resin composition. Such photocurable thermosetting resin compositions primarily contain a photosensitive polymer having a carboxyl group as a material, but may also contain an epoxy resin to improve the solder heat resistance of the cured product obtained after curing of the composition. However, because epoxy resins react relatively easily with photosensitive polymers having a carboxyl group, long-term storage stability of the composition is an issue. Therefore, a method has generally been used to prepare a photocurable thermosetting resin composition by blending the reactive components into separate compositions to form a two-part system, which is then mixed at the time of use. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 5688116 Summary of the Invention [Problem to be solved by the invention]

[0004] In recent years, the density of printed wiring boards has increased dramatically, with circuits now having line and space dimensions of as small as 10 μm and 10 μm, respectively, requiring higher insulation reliability than ever before. This increased density of printed circuit boards has led to the presence of particles of insoluble substances (inorganic fillers, crystalline epoxy resins, etc.) between fine pattern circuits, which have become the cause of short circuits between circuits. Furthermore, when a dry film was produced by applying a two-component photocurable thermosetting resin composition onto a carrier film and drying it, when the two-component resin compositions stored for one month after preparation were mixed and then applied to the carrier film, there were problems with long-term storage stability, such as the occurrence of repelling and pinholes due to coarse particles that were thought to have been generated during the storage period of the resin compositions stored in separate containers.

[0005] In response to this, for example, Patent Document 1 above discloses that attention is focused on epoxy resins among the components of photocurable thermosetting resin compositions, thereby preventing the generation of these coarse particles. However, as mentioned above, the density of printed wiring boards is increasing significantly, and higher insulation reliability is required for photocurable thermosetting resin compositions. There is a demand for further improvements in electrical properties (HAST resistance) by suppressing the generation of coarse particles due to various factors, not just epoxy resins. Furthermore, from the viewpoint of inventory security, it is desirable to obtain long-term storage stability, such as by suppressing the generation of coarse particles due to not only the epoxy resin but also various other factors, even one month after the preparation of each resin composition, and by suppressing the generation of repelling and pinholes during the dry film preparation process.

[0006] Therefore, an object of the present invention is to provide a photocurable thermosetting resin composition which is formulated into at least a two-component system, which has excellent electrical properties (HAST resistance) of the cured product, good long-term storage stability, and can suppress the occurrence of cissing and pinholes during the dry film production process. A further object of the present invention is to provide a dry film and a cured product which are obtained by using such an alkali-developable solder resist composition and which have the above-mentioned excellent properties, and a printed wiring board on which a cured coating such as a solder resist is formed using the dry film or the cured product. [Means for solving the problem]

[0007] As a result of intensive research by the present inventors, it has been found that the above-mentioned problems can be solved by a photocurable thermosetting resin composition comprising (A) an epoxy resin, (B) a carboxyl group-containing resin, (C) a photopolymerization initiator, (D) a photosensitive monomer, (E) silica, and (F) barium sulfate, To obtain the photocurable thermosetting resin composition, at least a two-component resin composition is prepared, the (B) carboxyl group-containing resin, the (D) photosensitive monomer, and the (E) silica are contained in a resin composition separate from the (A) epoxy resin, the (F) barium sulfate, and the (C) photopolymerization initiator; It was found that the above-mentioned resin composition containing the (C) photopolymerization initiator can be solved by a photocurable thermosetting resin composition which is formulated into at least a two-component system and contains an organic solvent capable of dissolving the (C) photopolymerization initiator, and the present invention was completed based on this finding. Among these, a preferred embodiment of the present invention relates to a photocurable thermosetting resin composition characterized in that the (A) epoxy resin contains three types of epoxy resins: a semi-solid or solid epoxy resin at room temperature, a biphenyl-type epoxy resin, and a novolac-type epoxy resin. A further preferred embodiment of the present invention relates to a photocurable thermosetting resin composition, wherein the composition containing the epoxy resin (A) has a viscosity of 4 dPa s or less, and the photocurable thermosetting resin composition obtained by mixing the respective resin compositions has a viscosity of 4 dPa s or less. An even more preferred embodiment of the present invention relates to a photocurable thermosetting resin composition, wherein the composition containing the (A) epoxy resin also contains the (C) photopolymerization initiator and an organic solvent, and the organic solvent is contained in an amount of 3 parts by mass or more per part by mass of the (C) photopolymerization initiator. Another aspect of the present invention relates to a dry film having a thickness of 10 μm to 30 μm, which is obtained by applying the above photocurable thermosetting resin composition to a carrier film and drying it. Yet another aspect of the present invention relates to the above-mentioned photocurable thermosetting resin composition, which is used as a solder resist material. Yet another aspect of the present invention relates to a cured product obtained by curing a photocurable thermosetting resin composition, a cured product obtained by curing a resin layer of a dry film, and an electronic component having these cured products. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a photocurable thermosetting resin composition which is formulated as at least a two-component system, and which has excellent electrical properties (HAST resistance) of a cured product obtained by curing the photocurable thermosetting resin composition, has good long-term storage stability of each resin composition, and can suppress the occurrence of cissing and pinholes during the dry film production process. Furthermore, according to the present invention, it is possible to provide a dry film and a cured product obtained by using such a photocurable thermosetting resin composition, which have the above-mentioned excellent properties, as well as electronic components such as printed wiring boards on which a cured coating such as a solder resist is formed using the dry film or the cured product. DETAILED DESCRIPTION OF THE INVENTION

[0009] The photocurable thermosetting resin composition of the present invention is preferably composed of at least a two-component resin composition. For example, a two-component system can be used in which one resin composition is a base composition and the other resin composition is a curing agent composition. In this case, for example, the base composition is preferably composed of (B) a carboxyl group-containing resin, (D) a photosensitive monomer, (E) silica, and, if necessary, an organic solvent, and the curing agent composition is preferably composed of (A) an epoxy resin, (C) a photopolymerization initiator, (F) barium sulfate, and an organic solvent capable of dissolving the (C) photopolymerization initiator. To prevent chemical reactions during storage, it is preferable that the (A) epoxy resin and (B) carboxyl group-containing resin, as well as the (D) photosensitive monomer and (C) photopolymerization initiator, are contained in separate compositions. Furthermore, because separation of the liquid surface of each composition (color floating or color separation), known as Benard cells, can occur and impair the appearance of the liquid surface of each composition, it is also preferable that the (E) silica and (F) barium sulfate are contained in separate compositions. Furthermore, if the (B) carboxyl group-containing resin and the (C) photopolymerization initiator are contained in the same composition, the composition may have a poor appearance and large particles may be produced, although the detailed mechanism is unknown. Therefore, it is preferable that the (B) carboxyl group-containing resin be contained in a composition separate from the (C) photopolymerization initiator and the organic solvent for dissolving it. Furthermore, it is preferable that the composition containing the epoxy resin (A) has a viscosity of 4 dPa·s or less, and that the photocurable thermosetting resin composition obtained by mixing the resin compositions has a viscosity of 0.1 dPa·s or more and 4 dPa·s or less, since this prevents precipitation of the epoxy resin (A). It is also preferable that the viscosity of the composition containing the epoxy resin (A) is 0.1 dPa·s or more, since this makes the composition easier to handle.

[0010] Each component constituting the photocurable thermosetting resin composition of the present invention will be described below.

[0011] [(A) Epoxy resin] The (A) epoxy resin functions as a thermosetting component in the photocurable thermosetting resin composition and forms a cured product. As such epoxy resin (A), a known and commonly used multifunctional epoxy resin having at least two epoxy groups in one molecule can be used. The (A) epoxy resin may be in a liquid state, or may be in a solid or semi-solid state. Preferred examples of polyfunctional epoxy resins include bisphenol A epoxy resins, brominated epoxy resins, novolac epoxy resins, bisphenol F epoxy resins, hydrogenated bisphenol A epoxy resins, glycidylamine epoxy resins, hydantoin epoxy resins, alicyclic epoxy resins, trihydroxyphenylmethane epoxy resins, bixylenol or biphenol epoxy resins or mixtures thereof, bisphenol S epoxy resins, bisphenol A novolac epoxy resins, tetraphenylolethane epoxy resins, heterocyclic epoxy resins, diglycidyl phthalate resins, tetraglycidylxylenoylethane resins, naphthalene group-containing epoxy resins, epoxy resins having a dicyclopentadiene skeleton, glycidyl methacrylate copolymer epoxy resins, cyclohexylmaleimide and glycidyl methacrylate copolymer epoxy resins, epoxy-modified polybutadiene rubber derivatives, CTBN-modified epoxy resins, and epoxy resins having an isocyanuric ring, but the present invention is not limited to these. These epoxy resins can be used alone or in combination of two or more. As the epoxy resin, it is preferable to use a novolac type epoxy resin in combination with an epoxy resin or biphenyl type epoxy resin that is semi-solid or solid at room temperature. The combined use of these epoxy resins can suppress the occurrence of cissing and pinholes during dry film formation. Furthermore, as a solid epoxy resin, an epoxy resin having a dicyclopentadiene skeleton is particularly preferable, as it has low water absorption and therefore excellent electrical properties. The blending ratio of novolac type epoxy resin to epoxy resin or biphenyl type epoxy resin that is semi-solid or solid at room temperature (epoxy resin:biphenyl type epoxy resin:novolac type epoxy resin) is preferably 1:1:1.5, more preferably 1:1:2.

[0012] The "epoxy resin that is solid or semi-solid at room temperature" in component (A) can also be any known or commonly used resin. For example, examples of epoxy resins that are solid at room temperature include bisphenol A epoxy resin (manufactured by Mitsubishi Chemical Corporation, jER1001), bisphenol F epoxy resin (manufactured by Mitsubishi Chemical Corporation, jER4004P), naphthalene epoxy resin (manufactured by DIC Corporation, HP-4700), naphthalene skeleton-containing multifunctional solid epoxy resin (manufactured by Nippon Kayaku Co., Ltd., NC-7000), trisphenol epoxy resin (manufactured by Nippon Kayaku Co., Ltd., EPPN-502H), dicyclopentadiene skeleton-containing multifunctional solid epoxy resin (manufactured by DIC Corporation, Epicron HP-7200), phosphorus-containing epoxy resin (manufactured by Nippon Steel & Sumikin Chemical Co., Ltd., TX0712), and tris(2,3-epoxypropyl)isocyanurate (manufactured by Nissan Chemical Industries, Ltd., TEPIC). Examples of epoxy resins that are semi-solid at room temperature include bisphenol A epoxy resin (manufactured by Mitsubishi Chemical Corporation, Epoxy resin (manufactured by DIC Corporation, HP-4032), and naphthalene type epoxy resin. Here, in the present invention, being solid or semi-solid at room temperature means being solid or semi-solid at 15° C. Whether a substance is solid or semi-solid can be determined in accordance with the "Method for Confirming Liquid State" in Appendix 2 of the Ministerial Ordinance on the Testing and Properties of Hazardous Materials (Ministry of Home Affairs Ordinance No. 1 of 1989). The biphenyl-type epoxy resin in component (A) may be a known, commonly used multifunctional epoxy resin having a biphenyl skeleton, such as a biphenyl-skeleton-containing multifunctional solid epoxy resin (NC-3000H, NC-3000, manufactured by Nippon Kayaku Co., Ltd.) or a biphenyl-type epoxy resin (YX-4000, YL-6121HA, manufactured by Mitsubishi Chemical Corporation). Examples of novolac epoxy resins in component (A) include cresol novolac epoxy resins (Epiclon N-690 manufactured by DIC Corporation) and phenol novolac epoxy resins (Epiclon N-770 manufactured by DIC Corporation, jER152 manufactured by Mitsubishi Chemical Corporation).

[0013] The content of the epoxy resin (A) as explained above is preferably in the range of about 30 to 60 parts by mass, more preferably 35 to 45 parts by mass, per 100 parts by mass of the carboxyl group-containing resin (B) described below.

[0014] [(B) Carboxyl group-containing resin] As the (B) carboxyl group-containing resin used in the present invention, various conventionally known carboxyl group-containing resins that have a carboxyl group in the molecule and further have no ethylenically unsaturated group (non-photosensitive) or have an ethylenically unsaturated group (photosensitive) can be used.

[0015] Specific examples of carboxyl group-containing resins having no ethylenically unsaturated groups include the following compounds (which may be either oligomers or polymers):

[0016] (1) Carboxyl group-containing urethane resins obtained by the polyaddition reaction of diisocyanates such as aliphatic diisocyanates, branched aliphatic diisocyanates, alicyclic diisocyanates, and aromatic diisocyanates with diol compounds containing carboxyl groups such as dimethylolpropionic acid and dimethylolbutanoic acid, such as dialcohol compounds, polycarbonate polyols, polyether polyols, polyester polyols, polyolefin polyols, bisphenol A alkylene oxide adduct diols, and compounds having phenolic hydroxyl groups and alcoholic hydroxyl groups.

[0017] (2) Carboxyl group-containing urethane resin obtained by polyaddition reaction of diisocyanate and carboxyl group-containing dialcohol compound.

[0018] (3) Carboxyl group-containing resins obtained by copolymerizing unsaturated carboxylic acids such as (meth)acrylic acid with unsaturated group-containing compounds such as styrene, α-methylstyrene, lower alkyl (meth)acrylates, and isobutylene.

[0019] (4) Carboxyl group-containing polyester resins obtained by reacting a dicarboxylic acid such as adipic acid, phthalic acid, or hexahydrophthalic acid with a difunctional epoxy resin or a difunctional oxetane resin, and then adding a dibasic acid anhydride such as phthalic anhydride, tetrahydrophthalic anhydride, or hexahydrophthalic anhydride to the resulting hydroxyl groups.

[0020] (5) A carboxyl group-containing resin obtained by ring-opening an epoxy resin or an oxetane resin and reacting the resulting hydroxyl group with a polybasic acid anhydride.

[0021] (6) A carboxyl group-containing resin obtained by reacting a polyalcohol resin or other reaction product obtained by reacting a compound having multiple phenolic hydroxyl groups in one molecule, i.e., a polyphenol compound, with an alkylene oxide such as ethylene oxide or propylene oxide, with a polybasic acid anhydride.

[0022] Specific examples of carboxyl group-containing resins having ethylenically unsaturated groups include the following compounds (which may be either oligomers or polymers): The ethylenically unsaturated bond in the carboxyl group-containing resin is preferably derived from acrylic acid, methacrylic acid, or a derivative thereof.

[0023] (7) Carboxyl group-containing photosensitive urethane resins obtained by the polyaddition reaction of diisocyanates such as aliphatic diisocyanates, branched aliphatic diisocyanates, alicyclic diisocyanates, and aromatic diisocyanates with diol compounds containing carboxyl groups such as dimethylolpropionic acid and dimethylolbutanoic acid, such as dialcohol compounds, polycarbonate polyols, polyether polyols, polyester polyols, polyolefin polyols, acrylic polyols, bisphenol A alkylene oxide adduct diols, and compounds having phenolic hydroxyl groups and alcoholic hydroxyl groups.

[0024] (8) Carboxyl group-containing photosensitive urethane resin obtained by the polyaddition reaction of diisocyanate with a (meth)acrylate of a bifunctional epoxy resin such as bisphenol A type epoxy resin, hydrogenated bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, bixylenol type epoxy resin, or biphenol type epoxy resin, or a partially acid anhydride-modified product thereof, and a carboxyl group-containing dialcohol compound.

[0025] (9) A carboxyl group-containing photosensitive urethane resin that is (meth)acrylated at the terminal by adding a compound having one hydroxyl group and one or more (meth)acryloyl groups in the molecule, such as hydroxyalkyl (meth)acrylate, during the synthesis of the resin (7) or (8) described above.

[0026] (10) A carboxyl group-containing photosensitive urethane resin that is (meth)acrylated at the end by adding a compound having one isocyanate group and one or more (meth)acryloyl groups in the molecule, such as an equimolar reaction product of isophorone diisocyanate and pentaerythritol triacrylate, during the synthesis of the resin (8) or (9) described above.

[0027] (11) A carboxyl group-containing photosensitive resin obtained by reacting a difunctional or more polyfunctional (solid) epoxy resin with (meth)acrylic acid and adding a dibasic acid anhydride to the hydroxyl groups present in the side chains.

[0028] (12) A carboxyl group-containing photosensitive resin in which the hydroxyl groups of a bifunctional (solid) epoxy resin are further epoxidized with epichlorohydrin, and then (meth)acrylic acid is reacted with the polyfunctional epoxy resin, and a dibasic acid anhydride is added to the resulting hydroxyl groups.

[0029] (13) Carboxyl group-containing polyester photosensitive resins obtained by reacting a dicarboxylic acid such as adipic acid, phthalic acid, or hexahydrophthalic acid with a bifunctional oxetane resin, and then adding a dibasic acid anhydride such as phthalic anhydride, tetrahydrophthalic anhydride, or hexahydrophthalic anhydride to the resulting primary hydroxyl groups.

[0030] (14) A carboxyl group-containing photosensitive resin obtained by reacting a compound having multiple phenolic hydroxyl groups in one molecule, i.e., a polyphenol compound, with an alkylene oxide such as ethylene oxide or propylene oxide to obtain a reaction product such as a polyalcohol resin, and then reacting the reaction product with an unsaturated group-containing monocarboxylic acid such as (meth)acrylic acid, and further reacting the resulting reaction product with a polybasic acid anhydride.

[0031] (15) A carboxyl group-containing photosensitive resin obtained by reacting a compound having multiple phenolic hydroxyl groups in one molecule with a cyclic carbonate compound such as ethylene carbonate or propylene carbonate, reacting the resulting reaction product with an unsaturated group-containing monocarboxylic acid, and then reacting the resulting reaction product with a polybasic acid anhydride.

[0032] (16) A carboxyl group-containing photosensitive resin obtained by further adding a compound having one epoxy group and one or more (meth)acryloyl groups in one molecule to the resins (3), (7) to (15) above.

[0033] These (B) carboxyl group-containing resins may be other than those described as (7) to (16), and may be used singly or in combination. Of the carboxyl group-containing resins, resins having aromatic rings are particularly preferred because of their excellent resolution.

[0034] The above-mentioned (B) carboxyl group-containing resin, whether photosensitive or non-photosensitive, has many carboxyl groups in the side chains of the backbone polymer, making it possible to develop it with a dilute alkaline aqueous solution.

[0035] The acid value of the (B) carboxyl group-containing resin is preferably in the range of 40 to 200 mgKOH / g, more preferably 45 to 120 mgKOH / g. If the acid value of the carboxyl group-containing resin is within this range, alkaline development becomes easier, dissolution of the exposed area by the developer is suppressed, and the lines do not become thinner than necessary, enabling normal pattern drawing that is not dissolved and peeled off by the developer.

[0036] The mass average molecular weight of the carboxyl group-containing resin (B) varies depending on the resin skeleton, but is generally preferably in the range of 2,000 to 150,000, and more preferably 5,000 to 100,000. If the mass average molecular weight is within this range, the tack-free performance is excellent, the moisture resistance of the coating film after exposure is good, and the resolution, developability, and storage stability are excellent.

[0037] The content of the carboxyl group-containing resin (B) in the base composition is preferably in the range of 30 to 70% by mass, and more preferably 45 to 60% by mass. If the amount of the carboxyl group-containing resin is within this range, the strength of the cured coating film will not decrease, and thickening or deterioration in workability will not occur.

[0038] [Acryloyl group-containing resin] The present invention may further include an acryloyl group-containing resin as the acrylate resin. The acryloyl group-containing resin of the present invention is a phenolic compound (a) having two or more phenolic hydroxyl groups in the molecule and having a structure of the following general formula (I), i.e., a novolac phenolic resin of a specific structure, obtained by a condensation reaction between a polymethylol of bisphenol A or bisphenol F and a phenol, thereby improving the drying properties of the ink composition before curing. Furthermore, flexibility is imparted by converting some or all of the phenolic hydroxyl groups of this resin to oxyalkyl groups having alcoholic hydroxyl groups, and acrylic acid and / or methacrylic acid (c) are added to the terminal hydroxyl groups of the resulting oxyalkyl groups, thereby imparting α,β-ethylenically unsaturated groups to the terminals of the side chains. This improves reactivity, achieves a high level of balance between heat resistance and toughness, and produces cured products that are excellent in hardness and flexibility, as well as in water resistance and chemical resistance. [ka] (In the formula, R1 is -C(CH3)2- or -CH2-, R2 is a hydrocarbon group having 1 to 11 carbon atoms, a is an integer of 0 to 3, n is an integer of 1 or 2, and m is an integer of 1 to 10.) The phenol compound (a) having two or more phenolic hydroxyl groups in the molecule containing the structure of the general formula (I) can be obtained by condensation reaction of a polymethylol of bisphenol A or bisphenol F with a phenol in the presence of an acidic catalyst. Phenols that can be used include phenol, various cresols, alkylphenols such as various xylenols, and naphthols, with o-cresol and 2,6-xylenol being preferred. These may also be used in combination. The addition ratio of the compound (b) having a cyclic ether group, such as alkylene oxide or cyclic carbonate, to the phenolic compound (a) is 0.5 mol, preferably 0.8 to 3.0 mol, per equivalent of the phenolic hydroxyl group of the phenolic compound (a). When the ratio is in the range of 0.5 to 5.0 mol, the resulting acryloyl group-containing photosensitive resin has excellent photocurability and drying properties. The content of such an acryloyl group-containing resin in the base composition is preferably in the range of 5 to 20% by mass, and more preferably 8 to 15% by mass.

[0039] [(C) Photopolymerization initiator] Examples of the (C) photopolymerization initiator include bis-(2,6-dichlorobenzoyl)phenylphosphine oxide, bis-(2,6-dichlorobenzoyl)-2,5-dimethylphenylphosphine oxide, bis-(2,6-dichlorobenzoyl)-4-propylphenylphosphine oxide, bis-(2,6-dichlorobenzoyl)-1-naphthylphosphine oxide, bis-(2,6-dimethoxybenzoyl)phenylphosphine oxide, and bis-(2,6-dimethoxybenzoyl)-2,4,4-thiazolinone. Bisacylphosphine oxides such as trimethylpentylphosphine oxide, bis-(2,6-dimethoxybenzoyl)-2,5-dimethylphenylphosphine oxide, and bis-(2,4,6-trimethylbenzoyl)-phenylphosphine oxide; 2,6-dimethoxybenzoyldiphenylphosphine oxide, 2,6-dichlorobenzoyldiphenylphosphine oxide, 2,4,6-trimethylbenzoylphenylphosphinic acid methyl ester, and 2-methylbenzoyldiphenylphosphine oxide. monoacylphosphine oxides such as phosphine oxide, pivaloylphenylphosphinic acid isopropyl ester, and 2,4,6-trimethylbenzoyldiphenylphosphine oxide; 1-hydroxy-cyclohexyl phenyl ketone, 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propan-1-one, 2-hydroxy-1-{4-[4-(2-hydroxy-2-methyl-propionyl)-benzyl]phenyl}-2-methyl-propan-1-one, and 2-hydroxy hydroxyacetophenones such as 2-methyl-1-phenylpropan-1-one; benzoins such as benzoin, benzil, benzoin methyl ether, benzoin ethyl ether, benzoin n-propyl ether, benzoin isopropyl ether, and benzoin n-butyl ether; benzoin alkyl ethers; benzophenones such as benzophenone, p-methylbenzophenone, Michler's ketone, methylbenzophenone, 4,4'-dichlorobenzophenone, and 4,4'-bisdiethylaminobenzophenone;Acetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, 1,1-dichloroacetophenone, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholino-1-propanone, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1, 2-(dimethylamino)-2-[(4-methylphenyl)methyl)-1-[4-(4-morpholinyl)phenyl]-1-butanone acetophenones such as thioxanthone, 2-ethylthioxanthone, 2-isopropylthioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2-chlorothioxanthone, 2,4-diisopropylthioxanthone; anthraquinone, chloroanthraquinone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-tert-butylanthraquinone, 1-chloroanthraquinone, 2-amylanthraquinone anthraquinones such as acetophenone dimethyl ketal and 2-aminoanthraquinone; ketals such as acetophenone dimethyl ketal and benzil dimethyl ketal; benzoic acid esters such as ethyl 4-dimethylaminobenzoate, 2-(dimethylamino)ethyl benzoate and p-dimethylbenzoic acid ethyl ester; 1,2-octanedione, 1-[4-(phenylthio)-, 2-(O-benzoyloxime)], ethanone, 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]-, 1-(O-acetyloxime) Examples of photopolymerization initiators include oxime esters such as bis(η5-2,4-cyclopentadien-1-yl)-bis(2,6-difluoro-3-(1H-pyrrol-1-yl)phenyl)titanium and titanocenes such as bis(cyclopentadienyl)-bis[2,6-difluoro-3-(2-(1-pyr-1-yl)ethyl)phenyl]titanium; phenyl disulfide 2-nitrofluorene, butyroin, anisoin ethyl ether, azobisisobutyronitrile, and tetramethylthiuram disulfide. The photopolymerization initiator may be used alone or in combination of two or more.

[0040] The content of the (C) photopolymerization initiator is preferably 5 to 15 parts by mass relative to 100 parts by mass of the (B) carboxyl group-containing resin. When the content is 5 parts by mass or more, the surface curing property is good, and when the content is 15 parts by mass or less, halation is unlikely to occur and good resolution is obtained.

[0041] [(D) Photosensitive Monomer] The photocurable thermosetting resin composition of the present invention that can form a cured product may contain a known and commonly used photosensitive monomer. (D) The photosensitive monomer may be, for example, a compound having one or more ethylenically unsaturated groups in the molecule. Such (D) photosensitive monomer (when it contains an ethylenically unsaturated group) assists in photocuring of the (B) carboxyl group-containing resin by irradiation with active energy rays, thereby curing the photocurable thermosetting resin composition.

[0042] The photosensitive monomer (D) preferably used in the present invention is, for example, methyl α-(allyloxymethyl)acrylate, 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, 1,9-nonanediol diacrylate, 1,Bifunctional diacrylates such as diol diacrylates such as 10-decanediol diacrylate, ethylene glycol diacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, tetraethylene glycol diacrylate, polyethylene glycol diacrylate, dipropylene glycol diacrylate, tripropylene glycol diacrylate, polypropylene glycol diacrylate, neopentyl glycol diacrylate, diol diacrylates obtained by adding at least one of ethylene oxide and propylene oxide to neopentyl glycol, glycol diacrylates such as caprolactone-modified hydroxypivalic acid neopentyl glycol diacrylate, bisphenol A EO adduct diacrylate, bisphenol A PO adduct diacrylate, diacrylates having a cyclic structure such as tricyclodecane dimethanol diacrylate, hydrogenated dicyclopentadienyl diacrylate, and cyclohexyl diacrylate, or the corresponding methacrylate monomers. Examples of suitable acrylates include polyfunctional acrylates such as trifunctional (meth)acrylate, pentaerythritol triacrylate, trimethylolpropane triacrylate, trimethylolmethane triacrylate, ethylene oxide-modified trimethylolpropane triacrylate, propylene oxide-modified trimethylolpropane triacrylate, epichlorohydrin-modified trimethylolpropane triacrylate, pentaerythritol tetraacrylate, pentaerythritol tetramethacrylate, tetramethylolmethane tetraacrylate, ethylene oxide-modified phosphate triacrylate, epichlorohydrin-modified glycerol triacrylate, dipentaerythritol hexaacrylate, dipentaerythritol monohydroxypentaacrylate, and silsesquioxane-modified versions of these, as well as corresponding methacrylate monomers, trifunctional methacrylate esters, and polyfunctional (meth)acrylates such as ε-caprolactone-modified tris(acryloxyethyl)isocyanurate, and combinations of two or more of these.

[0043] The content of such (D) photosensitive monomer is preferably in the range of 10 to 27 parts by mass, more preferably 15 to 20 parts by mass, per 100 parts by mass (solid content) of the (B) carboxyl group-containing resin. If the content of the (D) photosensitive monomer is within this range, the photocurable thermosetting resin composition has sufficient photocurability, and patterning during development is improved, and tackiness (dryness to the touch) is also improved.

[0044] [(E) Silica] In the present invention, (E) silica is preferably contained as a filler in the base composition in the case of a two-component system. (E) silica is preferably used in the present invention because of its low moisture absorption and low volume expansion properties. (E) Silica may be either amorphous or crystalline, or a mixture of these, but amorphous silica is preferred. In the present invention, from the viewpoint of ease of handling, such as maintaining the degree of dispersion, it is generally preferred that the (E) silica be used as a slurry dispersed in a solvent.

[0045] [(F) Barium sulfate] In the present invention, (F) barium sulfate also functions as a filler, similar to (E) silica, but is preferably contained separately from (E) silica in the hardener composition rather than in the base composition. This is because there is a risk of Benard cells forming, which may impair the appearance of the composition coating film obtained from the mixed composition. In the present invention, from the viewpoint of ease of handling, such as maintaining the degree of dispersion, it is usually preferable to use (F) barium sulfate as a slurry dispersed in a solvent.

[0046] The (E) silica and (F) barium sulfate are preferably surface-treated, and more preferably have been subjected to a surface treatment that allows the introduction of curable reactive groups onto their surfaces. Here, the curable reactive group refers to a group that undergoes a curing reaction with (A) an epoxy resin or (B) a carboxyl group-containing resin, and may be a photocurable reactive group or a thermosetting reactive group. Examples of the photocurable reactive group include a methacrylic group, an acrylic group, a vinyl group, and a styryl group. Examples of the thermosetting reactive group include an epoxy group, an amino group, a hydroxyl group, a carboxyl group, an isocyanate group, an imino group, an oxetanyl group, a mercapto group, a methoxymethyl group, a methoxyethyl group, an ethoxymethyl group, an ethoxyethyl group, and an oxazoline group. The method for introducing curable reactive groups into the surfaces of (E) silica and (F) barium sulfate is not particularly limited, and may be carried out using a known, commonly used method. The surface of the inorganic filler may be treated with a surface treatment agent having a curable reactive group, such as a coupling agent having a curable reactive group as an organic group. Examples of the coupling agent include silane coupling agents, titanium coupling agents, zirconium coupling agents, and aluminum coupling agents. Examples of surface-treated inorganic fillers that do not have curable reactive groups include inorganic fillers that have been surface-treated with silica-alumina, titanate-based coupling agents, aluminate-based coupling agents, or organically treated.

[0047] The average particle size (D50) of the (E) silica slurry is preferably 2000 nm or less, more preferably 1200 nm or less, and the lower limit of the average particle size (D50) is preferably 0.1 nm or more. The average particle size (D50) of the (F) barium sulfate slurry is 1000 nm or less, and more preferably 500 nm or less. The lower limit of the average particle size (D50) is preferably 0.1 nm or more. The smaller the average particle size of (E) silica and (F) barium sulfate, the more easily it is possible to suppress diffused reflection during light irradiation and to facilitate fine processing of the cured product pattern. The average particle size (D50) can be determined using a laser diffraction particle size distribution analyzer and a dynamic light scattering analyzer. Examples of the laser diffraction analyzer include the MicrotracMT3300EXII manufactured by Microtrac-Bell, and examples of the dynamic light scattering analyzer include the Nanotrac Wave II UT151 manufactured by Microtrac-Bell.

[0048] The content of (E) silica and (F) barium sulfate is more preferably 15% by mass to 30% by mass, respectively, relative to the total amount of non-volatile components in the photocurable thermosetting resin composition of the present invention, from the viewpoint that the properties required for a solder resist, such as suppression of heat buildup, high resolution, and good crack resistance, can be imparted to the composition.

[0049] [Organic solvents] In the present invention, an organic solvent may be used for preparing the photocurable thermosetting resin composition or adjusting its viscosity, or for preparing the (E) silica slurry or the (F) barium sulfate slurry. Examples of such organic solvents include ketones such as methyl ethyl ketone and cyclohexanone; aromatic hydrocarbons such as toluene, xylene, and tetramethylbenzene; glycol ethers such as cellosolve, methyl cellosolve, butyl cellosolve, carbitol, methyl carbitol, butyl carbitol, propylene glycol monomethyl ether, dipropylene glycol monomethyl ether (DPM), dipropylene glycol diethyl ether, and tripropylene glycol monomethyl ether; esters such as ethyl acetate, butyl acetate, butyl lactate, cellosolve acetate, butyl cellosolve acetate, carbitol acetate, butyl carbitol acetate, propylene glycol monomethyl ether acetate, dipropylene glycol monomethyl ether acetate, and propylene carbonate; aliphatic hydrocarbons such as octane and decane; and petroleum-based solvents such as petroleum ether, petroleum naphtha, and solvent naphtha. These organic solvents can be used alone or in combination of two or more kinds. The content of the organic solvent is preferably in the range of 5% to 25% by mass relative to the base composition of the photocurable thermosetting resin composition of the present invention, and this content of the organic solvent also includes the organic solvent in the slurry of (E) silica. The curing agent composition preferably contains an organic solvent capable of dissolving the (C) photopolymerization initiator blended into the composition, with the organic solvent being 3 parts by mass or more per 1 part by mass of the (C) photopolymerization initiator. An organic solvent capable of dissolving the (C) photopolymerization initiator means an organic solvent that, as a result of the "Photopolymerization initiator solubility confirmation test" described below, results in "Good: No crystals of the photopolymerization initiator were observed visually" (see Table 1). By selecting and using such an organic solvent, crystals of the (C) photopolymerization initiator do not form, thereby suppressing the generation of coarse particles. Among the organic solvents listed in Table 1, PMA and CA are preferred because they provide excellent coatability and dryness to touch after mixing of the photocurable thermosetting resin composition. Therefore, it is more preferable to use PMA alone or a mixed solvent of PMA and CA. The upper limit of the organic solvent content can be appropriately adjusted based on the maximum dissolving amount of the photopolymerization initiator (C) (see Table 2 below). The upper limit can be appropriately adjusted in the same manner for photopolymerization initiators other than Omnirad TPO H listed in Tables 1-2 to 1-5.

[0050] [Other ingredients] In the photocurable thermosetting resin composition of the present invention, it is of course possible to blend further additives as other components, if necessary, within the scope of the object of the present invention. Examples of such components include colorants such as pigments and dyes, thermal polymerization inhibitors, ultraviolet absorbers, plasticizers, flame retardants, antistatic agents, antioxidants, antibacterial and antifungal agents, leveling agents, thickeners, adhesion imparting agents, thixotropy imparting agents, photoinitiator assistants, sensitizers, photobase generators, thermoplastic resins, elastomers, organic fillers, fillers other than silica and barium sulfate, release agents, surface treatment agents, dispersants, dispersion assistants, surface modifiers, stabilizers, fluorescent materials, cellulose resins, and the like.

[0051] The base composition and the curing agent composition of the photocurable thermosetting resin composition of the present invention can be prepared by mixing and dispersing the respective components in predetermined amounts using, for example, a three-roll mill.

[0052] [Dry film] The photocurable thermosetting resin composition of the present invention is preferably used in the form of a dry film. The dry film of the present invention has a resin layer obtained by applying and drying the photocurable thermosetting resin composition of the present invention to a carrier film. To form the dry film, first, in the case of a two-component system, the base composition and the curing agent composition are thoroughly mixed to obtain the photocurable thermosetting resin composition of the present invention. This composition is then applied to a carrier film in a uniform thickness using a comma coater, blade coater, lip coater, rod coater, squeeze coater, reverse coater, transfer roll coater, gravure coater, spray coater, or the like, either directly or after diluting with an organic solvent as needed to adjust the viscosity. The applied composition is then typically dried at a temperature of 50 to 130°C for 1 to 30 minutes to form a resin layer. The thickness of the applied film is not particularly limited, but is generally selected appropriately within the range of 10 to 150 μm, preferably 20 to 60 μm, after drying.

[0053] As the carrier film, a plastic film is used, and examples thereof include polyester films such as polyethylene terephthalate (PET), polyimide films, polyamideimide films, polypropylene films, polystyrene films, etc. There are no particular restrictions on the thickness of the carrier film, but it is generally selected appropriately in the range of 10 to 150 μm.

[0054] After forming a resin layer made of the photocurable thermosetting resin composition of the present invention on a carrier film, it is preferable to further laminate a peelable cover film on the surface of the resin layer for the purpose of preventing dust from adhering to the surface of the resin layer. As the peelable cover film, for example, a polyethylene film, a polytetrafluoroethylene film, a polypropylene film, surface-treated paper, etc. can be used. The cover film may be any material as long as the adhesive strength between the resin layer and the carrier film is smaller when the cover film is peeled off.

[0055] In the present invention, the photocurable thermosetting resin composition of the present invention may be applied to the cover film and dried to form a resin layer, and then a carrier film may be laminated on the surface of the resin layer. That is, in the present invention, when producing a dry film, either a carrier film or a cover film may be used as the film to which the curable composition of the present invention is applied.

[0056] Here, the photocurable thermosetting resin composition of the present invention can be adjusted to a viscosity suitable for the coating method using an organic solvent, and applied to a substrate by a method such as dip coating, flow coating, roll coating, bar coating, screen printing, or curtain coating, followed by volatilization and drying (pre-drying) of the organic solvent contained in the composition at a temperature of about 60 to 100° C. A tack-free resin layer can also be formed. Furthermore, in the case of a dry film obtained by coating the composition on a carrier film or cover film, drying it, and winding it up as a film, the resin layer can be formed by laminating the composition of the present invention onto the substrate using a laminator or the like so that the layer of the composition contacts the substrate, and then peeling off the carrier film.

[0057] The substrates include printed wiring boards and flexible printed wiring boards with circuits already formed using copper or the like, as well as copper-clad laminates for high-frequency circuits made from materials such as paper phenol, paper epoxy, glass cloth epoxy, glass polyimide, glass cloth / non-woven cloth epoxy, glass cloth / paper epoxy, synthetic fiber epoxy, fluororesin, polyethylene, polyphenylene ether, polyphenylene oxide, cyanate, etc., including copper-clad laminates of all grades (FR-4, etc.), as well as metal substrates, polyimide film, PET film, polyethylene naphthalate (PEN) film, glass substrates, ceramic substrates, wafer plates, etc.

[0058] [Cured product] To form a cured product using the photocurable thermosetting resin composition of the present invention, the composition is applied to a substrate, the solvent is evaporated, and the resulting resin layer is then exposed (irradiated with light) to cure the exposed areas. Specifically, a resist pattern is formed by selectively exposing the composition to active energy rays through a patterned photomask using a contact or non-contact method, or by directly exposing the pattern using a laser direct exposure device, and developing the unexposed areas with an alkaline aqueous solution (e.g., a 0.3 to 3 wt% sodium carbonate aqueous solution). Further heat curing (post-cure) by heating to a temperature of approximately 100 to 180°C results in the formation of a cured film (cured product) with excellent properties such as heat resistance, chemical resistance, moisture absorption resistance, adhesion, and electrical properties.

[0059] The volatilization drying or thermal curing when forming the cured product can be carried out using, for example, a hot air circulation drying oven, an IR oven, a hot plate, a convection oven, etc. (a method in which hot air in a dryer equipped with a heat source of an air heating method using steam is brought into countercurrent contact with the substrate, or a method in which hot air is blown onto the substrate from a nozzle).

[0060] The exposure device used for the active energy ray irradiation may be a device equipped with a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, a metal halide lamp, a mercury short arc lamp, or the like, and capable of irradiating ultraviolet light in the range of 350 to 450 nm. Direct imaging devices (e.g., laser direct imaging devices that directly draw images with a laser based on CAD data from a computer) can also be used. The lamp or laser light source for the direct imaging device may have a maximum wavelength in the range of 350 to 410 nm. The exposure dose for image formation varies depending on factors such as the film thickness, but is generally in the range of 20 to 1000 mJ / cm², preferably 20 to 800 mJ / cm².

[0061] The developing method may be a dipping method, a shower method, a spray method, a brush method, or the like, and the developing solution may be an aqueous alkali solution such as potassium hydroxide, sodium hydroxide, sodium carbonate, potassium carbonate, sodium phosphate, sodium silicate, ammonia, or an amine.

[0062] [Electronic Components] The present invention can also provide an electronic component having the above-mentioned cured product. By using the photocurable thermosetting resin composition of the present invention, electronic parts with high quality, durability and reliability can be provided. In the present invention, electronic components refer to components used in electronic circuits, and include active components such as printed wiring boards, transistors, light-emitting diodes, and laser diodes, as well as passive components such as resistors, capacitors, inductors, and connectors.

[0063] Hereinafter, one embodiment of the present invention will be specifically illustrated by way of an example, but it goes without saying that the purpose is not to limit the scope of the invention according to the claims of this application. Unless otherwise specified, the "parts" and "%" shown are based on mass. [Example]

[0064] Test Example 1: Confirmation of the solubility of the photopolymerization initiator Prior to experiments on the properties of the photocurable thermosetting resin composition of the present invention, preliminary tests were conducted to confirm the solubility of five types of photopolymerization initiators in organic solvents in order to select an organic solvent suitable for the photopolymerization initiator, as described below. First, tests were carried out to confirm the approximate solubility of five photopolymerization initiators in various organic solvents, and the results were used as a guide for determining the amounts to be added thereafter (Tables 1-1 to 1-5). Next, the four solvents were added in predetermined amounts to the prepared vials, and then a photoinitiator (Omnirad TPO H) was added to the vials. The vials were then manually shaken and allowed to stand for 5 minutes. The presence or absence of photoinitiator crystals was then visually confirmed. If no crystals were observed, additional photoinitiator was added, manually stirred, and allowed to stand for 5 minutes. This procedure was repeated until crystals were observed. Finally, if crystals were observed after leaving the system for 5 minutes, the addition of the photoinitiator was terminated, and the amount added before crystals were observed was designated the maximum amount of Omnirad TPO H photoinitiator added (Table 2). The evaluation criteria are as follows: ◯: No crystals of the photopolymerization initiator were observed visually ×: Crystals of the photopolymerization initiator were observed visually (did not dissolve over time) The results are shown in Tables 1-1 to 1-5 and Table 2 below.

[0065] [Table 1]

[0066] [Table 2]

[0067] [Table 3]

[0068] [Table 4]

[0069] [Table 5]

[0070] [Table 6] *The photopolymerization initiators and organic solvents listed in Tables 1-1 to 1-5 and Table 2 are as follows. TPO: Acylphosphine oxide photoinitiator (Omnirad TPO H, manufactured by IGM Resins BV) (2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide) 907: α-aminoacetophenone photoinitiator (IGM Resins Omnirad 907) (2-methyl-1-(4-methylthiophenyl)-2-morpholinopropan-1-one) 379: Alkylphenone photoinitiator (Omnirad 379EG, manufactured by IGM Resins BV) (2-(dimethylamino)-2-(4-methylbenzyl)-1-(4-morpholinophenyl)butan-1-one) ·784: Titanocene photopolymerization initiator (JMT-784 manufactured by Yueyang Jin Maotai Technology Co., Ltd.) OXE02: Oxime ester photoinitiator (BASF Japan, Irgacure OXE02 (ethanone, 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]-1-(o-acetyloxime) PMA (Propylene Glycol Monomethyl Ether Acetate) CA (Carbitol Acetate) GBL (γ-butyrolactone) MEK (methyl ethyl ketone)

[0071] [Synthesis Example 1: Synthesis of Carboxyl Group-Containing Resin (B-1)] A flask equipped with a condenser and a stirrer was charged with 456 parts of bisphenol A, 228 parts of water, and 649 parts of 37% formalin. While maintaining the temperature below 40°C, 228 parts of 25% aqueous sodium hydroxide was added. The reaction was continued for 10 hours at 50°C. After the reaction was completed, the mixture was cooled to 40°C and neutralized to pH 4 with 37.5% aqueous phosphoric acid while maintaining the temperature below 40°C. The mixture was then allowed to stand and the aqueous layer was separated. After separation, 300 parts of methyl isobutyl ketone was added and uniformly dissolved, followed by washing three times with 500 parts of distilled water. Water, solvent, etc. were removed under reduced pressure at a temperature below 50°C. The resulting polymethylol compound was dissolved in 550 parts of methanol to obtain 1230 parts of a methanol solution of the polymethylol compound. A portion of the resulting methanol solution of the polymethylol compound was dried at room temperature in a vacuum dryer, revealing a solids content of 55.2%.

[0072] 500 parts of the resulting methanol solution of the polymethylol compound and 440 parts of 2,6-xylenol were charged and homogeneously dissolved at 50°C. After homogeneous dissolution, methanol was removed under reduced pressure at a temperature below 50°C. 8 parts of oxalic acid was then added, and the reaction was carried out at 100°C for 10 hours. After completion of the reaction, distillate was removed under reduced pressure at 180°C and 50 mmHg, yielding 550 parts of novolak resin A. Furthermore, 130 parts of the above novolak resin A, 2.6 parts of a 50% aqueous sodium hydroxide solution, and 100 parts of toluene / methyl isobutyl ketone (mass ratio = 2 / 1) were charged into an autoclave equipped with a thermometer, a nitrogen introducing device / alkylene oxide introducing device, and a stirrer. The system was purged with nitrogen while stirring, and then heated to 150°C and 8 kg / cm. 2 45 parts of ethylene oxide was gradually introduced and the reaction was carried out at a gauge pressure of 0.0 kg / cm. 2 The reaction was continued for about 4 hours until the reaction mixture reached a concentration of 1.0%, after which it was cooled to room temperature. 3.3 parts of a 36% aqueous solution of hydrochloric acid was added to and mixed with the reaction solution to neutralize the sodium hydroxide. The neutralized reaction product was diluted with toluene, washed with water three times, and the solvent was removed using an evaporator to obtain an ethylene oxide adduct of novolak resin A with a hydroxyl value of 175 g / eq. This product had an average of 1 mole of ethylene oxide added per equivalent of phenolic hydroxyl group.

[0073] 175 parts of the ethylene oxide adduct of novolak resin A, 50 parts of acrylic acid, 3.0 parts of p-toluenesulfonic acid, 0.1 parts of hydroquinone monomethyl ether, and 130 parts of toluene were charged into a reactor equipped with a stirrer, thermometer, and air inlet tube, and the mixture was stirred while blowing in air. The temperature was raised to 115°C, and the reaction was continued for another 4 hours while distilling off the water produced by the reaction as an azeotrope with toluene. The reaction solution was washed with 5% aqueous NaCl solution, and the toluene was removed by distillation under reduced pressure. Diethylene glycol monoethyl ether acetate was then added to obtain an acrylate resin solution with a solids content of 68%.

[0074] Next, 312 parts of the obtained acrylate resin solution, 0.1 parts of hydroquinone monomethyl ether, and 0.3 parts of triphenylphosphine were charged into a four-neck flask equipped with a stirrer and a reflux condenser, and the mixture was heated to 110°C, and 45 parts of tetrahydrophthalic anhydride was added. The mixture was reacted for 4 hours, cooled, and then removed. The carboxyl group-containing resin (B-1) thus obtained had a nonvolatile content of 72% and an acid value of 65 mgKOH / g of solids.

[0075] [Synthesis Example 2: Synthesis of Carboxyl Group-Containing Resin (B-2)] An autoclave equipped with a thermometer, a nitrogen / alkylene oxide inlet, and a stirrer was charged with 119.4 parts of cresol novolac resin (Aica Kogyo Shonol CRG-951, OH equivalent: 119.4), 1.19 parts of potassium hydroxide, and 119.4 parts of toluene. The system was purged with nitrogen while stirring and heated to a temperature of 100°C. Next, 63.8 parts of propylene oxide was slowly added dropwise, and the reaction was carried out at 125-132°C and 0-4.8 kg / cm² for 16 hours. The reaction solution was then cooled to room temperature, and 1.56 parts of 89% phosphoric acid was added and mixed to neutralize the potassium hydroxide, yielding a propylene oxide reaction solution of novolac cresol resin with a nonvolatile content of 62.1% and a hydroxyl value of 182.2 mgKOH / g (307.9 g / eq.). This was found to be a product in which an average of 1.08 moles of propylene oxide was added per equivalent of phenolic hydroxyl group.

[0076] 293.0 parts of the resulting propylene oxide reaction solution of novolac cresol resin, 43.2 parts of acrylic acid, 11.53 parts of methanesulfonic acid, 0.18 parts of methylhydroquinone, and 252.9 parts of toluene were introduced into a reactor equipped with a stirrer, thermometer, and air inlet tube. Air was blown in at a rate of 10 ml / min, and the mixture was stirred at 110°C for 12 hours. The water produced by the reaction was distilled off as an azeotrope with toluene, resulting in 12.6 parts of water being distilled off. The mixture was then cooled to room temperature, neutralized with 35.35 parts of 15% aqueous sodium hydroxide, and then washed with water. The toluene was then replaced with 118.1 parts of diethylene glycol monoethyl ether acetate and distilled off using an evaporator, yielding a novolac acrylate resin solution.

[0077] Next, 332.5 parts of the resulting novolac acrylate resin solution and 1.22 parts of triphenylphosphine were introduced into a reactor equipped with a stirrer, thermometer, and air inlet tube, and 60.8 parts of tetrahydrophthalic anhydride were gradually added while stirring and blowing air into the mixture at a rate of 10 ml / min. The mixture was reacted at 95-101°C for 6 hours, cooled, and then removed. In this way, a carboxyl group-containing resin (B-2) was obtained with a solid content of 65% and an acid value of 87.7 mgKOH / g of the solid content.

[0078] [Synthesis Example 3: Synthesis of acryloyl group-containing resin] A flask equipped with a condenser and stirrer was charged with 456 parts of bisphenol A, 228 parts of water, and 649 parts of 37% formalin. While maintaining the temperature below 40°C, 228 parts of 25% aqueous sodium hydroxide was added. The reaction was continued for 10 hours at 50°C. After the reaction was completed, the mixture was cooled to 40°C and neutralized to pH 4 with 37.5% aqueous phosphoric acid while maintaining the temperature below 40°C. The mixture was then allowed to stand and the aqueous layer was separated. After separation, 300 parts of methyl isobutyl ketone was added and the mixture was uniformly dissolved. The mixture was then washed three times with 500 parts of distilled water. The water and solvent were removed under reduced pressure at a temperature below 50°C. The resulting polymethylol compound was dissolved in 550 parts of methanol to obtain 1230 parts of a methanol solution of the polymethylol compound. A portion of the resulting methanol solution of the polymethylol compound was dried at room temperature in a vacuum dryer, revealing a solids content of 55.2%.

[0079] 500 parts of the resulting methanol solution of the polymethylol compound and 440 parts of 2,6-xylenol were charged and homogeneously dissolved at 50°C. After homogeneous dissolution, methanol was removed under reduced pressure at a temperature below 50°C. 8 parts of oxalic acid was then added, and the reaction was carried out at 100°C for 10 hours. After completion of the reaction, distillate was removed under reduced pressure at 180°C and 50 mmHg, yielding 550 parts of novolak resin A. Furthermore, 130 parts of the above novolak resin A, 2.6 parts of a 50% aqueous sodium hydroxide solution, and 100 parts of toluene / methyl isobutyl ketone (mass ratio = 2 / 1) were charged into an autoclave equipped with a thermometer, a nitrogen introducing device / alkylene oxide introducing device, and a stirrer. The system was purged with nitrogen while stirring, and then heated to 150°C and 8 kg / cm. 2 45 parts of ethylene oxide was gradually introduced and the reaction was carried out at a gauge pressure of 0.0 kg / cm. 2 The reaction was continued for about 4 hours until the reaction mixture reached a concentration of 1.0%, after which it was cooled to room temperature. 3.3 parts of a 36% aqueous solution of hydrochloric acid was added to and mixed with the reaction solution to neutralize the sodium hydroxide. The neutralized reaction product was diluted with toluene, washed with water three times, and the solvent was removed using an evaporator to obtain an ethylene oxide adduct of novolak resin A with a hydroxyl value of 175 g / eq. This product had an average of 1 mole of ethylene oxide added per equivalent of phenolic hydroxyl group.

[0080] 175 parts of the ethylene oxide adduct of novolak resin A, 75 parts of methacrylic acid, 3.0 parts of p-toluenesulfonic acid, 0.1 parts of hydroquinone monomethyl ether, and 130 parts of toluene were placed in a reactor equipped with a stirrer, thermometer, and air inlet tube. The mixture was stirred while blowing in air, heated to 115°C, and the reaction was continued for another 4 hours while distilling off the water produced by the reaction as an azeotrope with toluene. The mixture was then cooled to room temperature. The resulting reaction solution was washed with 5% aqueous NaCl solution, and the toluene was removed by vacuum distillation. Diethylene glycol monoethyl ether acetate was then added to obtain an acryloyl group-containing resin solution with a solids content of 68%.

[0081] (E) Preparation of silica slurry 700 g of spherical silica (SO-E2 manufactured by Admatec Co., Ltd.), 295 g of propylene glycol monomethyl ether acetate (PMA) as a solvent, and 5 g of a wetting and dispersing agent were mixed and stirred, and then dispersed in a bead mill using 0.5 μm zirconia beads. This process was repeated three times, and the mixture was filtered through a 3 μm filter to produce (E) silica slurry. The average particle size (D50) of the resulting silica slurry was 1200 nm or less.

[0082] (F) Preparation of barium sulfate slurry 700 g of barium sulfate (B-30 manufactured by Sakai Chemical Industry Co., Ltd.), 295 g of diethylene glycol monoethyl ether acetate (carbitol acetate) as a solvent, and 5 g of a wetting dispersant were mixed and stirred, and dispersed in a bead mill as described above. This process was repeated three times and filtered through a 3 μm filter to produce barium sulfate slurry (F). The average particle size (D50) of the resulting barium sulfate slurry was less than 500 nm.

[0083] [Examples 1 to 5 and Comparative Examples 1 to 3] The components shown in Tables 3 and 4 below were premixed in the respective amounts using a stirrer, and then kneaded using a three-roll mill to prepare the photocurable thermosetting resin compositions (two-component systems consisting of a base composition and a curing agent composition) of Examples 1 to 5 and Comparative Examples 1 to 3, respectively.

[0084] [Table 7]

[0085] [Table 8] *1 Follow Synthesis Example 1 *2 Follow Synthesis Example 2 *3 Follow Synthesis Example 3 *4 CIPigment red 149 *5 CIPigment yellow 147 *6 Copper Phthalocyanine Blue: *7 Carbon black: MA-100 (Mitsubishi Chemical Corporation) *8 melamine *9 BYK-350 (manufactured by BYK Japan) *10 DPHA: Dipentaerythritol hexaacrylate (hexafunctional acrylic monomer, manufactured by Nippon Kayaku Co., Ltd.) *11 Laromer LR8863: EO-modified trimethylolpropane triacrylate (BASF Japan) *12 (E) Silica slurry *13 PMA (Propylene Glycol Monomethyl Ether Acetate) *14 (F) Barium sulfate slurry *15 CA (Carbitol Acetate) *16 Omnirad TPO H: Acylphosphine oxide photoinitiator (manufactured by IGM Resins B.V.) *17 JMT784: Titanocene photopolymerization initiator (manufactured by Yueyang Jin Maotai Technology Co., Ltd.) *18 Quinopower QS-30: Naphthoquinone polymerization inhibitor (Kawasaki Chemical Industries, Ltd.) *19 PMA (Propylene Glycol Monomethyl Ether Acetate) *20 GBL (γ-butyrolactone) *21 MEK (methyl ethyl ketone) *22 Dicyclopentadiene epoxy resin (HP-7200L; manufactured by DIC Corporation) *23 BisA type epoxy resin (jER834; Mitsubishi Chemical Corporation) *24 Biphenyl type epoxy resin *25 Novolac Epoxy Resin

[0086] The obtained base compositions, curing agent compositions and photocurable thermosetting resin compositions obtained by mixing these compositions of Examples 1 to 5 and Comparative Examples 1 to 3 were subjected to the following tests.

[0087] <Dispersion degree (initial), initial viscosity> The viscosity of each of the base composition, curing agent composition, and photocurable thermosetting resin composition obtained by thoroughly mixing the base composition and curing agent composition in Examples 1 to 5 and Comparative Examples 1 to 3 was measured using a cone-plate viscometer (model number: TVE-33H, manufactured by Tokyo Keiki Inc.) at a measurement temperature of 25°C and a cone rotation speed of 5 rpm / min, and the measured value was recorded as the initial viscosity. The degree of dispersion was measured by particle size measurement using a grind meter (manufactured by Yasuda Seiki Seisakusho Co., Ltd.), and the measured value was recorded as the degree of dispersion (initial). The results are summarized in Table 5 below.

[0088] [Table 9]

[0089] <Dispersion (over time)> For each of the base composition and curing agent composition of Examples 1 to 5 and Comparative Examples 1 to 3, the degree of dispersion was measured 5 days, 10 days, 15 days, 20 days, and 30 days after preparation when stored at 20°C and when stored at 5°C by particle size measurement using a grind meter (manufactured by Yasuda Seiki Seisakusho), and the numerical value was taken as the degree of dispersion (over time). The evaluation criteria are as follows: <10μm: 〇 <12.5μm:△ <20μm: × The results are summarized in Table 6 below.

[0090] [Table 10]

[0091] <Appearance of composition> For each of the base composition and curing agent composition of Examples 1 to 5 and Comparative Examples 1 to 3, when stored at 20°C, the surface of each composition was visually inspected 5 days, 10 days, 15 days, 20 days, and 30 days after preparation. The evaluation criteria are as follows: No surface separation: Yes Surface separation: × The results are summarized in Table 7 below.

[0092] [Table 11]

[0093] <Appearance of dry film> The base compositions and curing agent compositions of Examples 1-5 and Comparative Examples 1-3 were stored at 20°C. After 5, 10, 15, 20, and 30 days, the resulting photocurable thermosetting resin compositions were mixed together. A dilution solvent was then added to adjust the viscosity to 4 d·Ps. The diluted photocurable thermosetting resin compositions were then applied to PET film using an applicator to achieve dry film thicknesses of 15 μm and 30 μm, respectively, and dried in a hot air circulating oven for 30 minutes. The resulting coating surfaces (30 cm × 30 cm) were then observed under a 20x optical microscope to determine the number of repelling and pinholes. The evaluation criteria are as follows: 0 pieces :○ 1 or more and 5 or less: △ More than 5 but less than 10:× The results are summarized in Table 8 below.

[0094] [Table 12]

[0095] <Electrical characteristics> Dry films were obtained from the photocurable thermosetting resin compositions obtained by mixing the base composition and curing agent composition of Examples 1 to 5 and Comparative Examples 1 to 3, using a comb-shaped electrode pattern with a line / space of 20 / 20 μm instead of a copper foil substrate. Vacuum heat lamination was performed on the obtained dry films, and a bias voltage of DC 10 V was applied. The time until the insulation resistance value reached 10Ω or less at 130°C / 85% was measured. The average time was calculated using five pieces. The evaluation criteria are as follows: Connection time: 200 hours or more and 250 hours or less: Yes Connection time: 150 hours or more but less than 200 hours: × The results are summarized in Table 9 below.

[0096] [Table 13]

[0097] The results shown in the table above demonstrate that the photocurable thermosetting resin composition of the present invention has excellent electrical properties. For both the base composition and the curing agent composition of the present invention, particle size measurements using a grindmeter showed a particle size of <10 μm from the initial stage to 30 days after storage, with no generation of coarse particles, demonstrating excellent dispersion and storage stability. Furthermore, with regard to the appearance of the composition, there were no problems such as surface separation for both the base composition and the curing agent composition even after 30 days of storage, demonstrating excellent storage stability. Furthermore, the photocurable thermosetting resin composition of the present invention exhibits excellent storage stability, as no repelling or pinholes occur when forming a dry film even after storage for up to 30 days. On the other hand, the base composition of Comparative Example 1 contains both (B) a carboxyl group-containing resin and (C) a photopolymerization initiator, and although the detailed mechanism is unclear, it is clear that the dispersion degree (over time) and the stability of the composition's appearance over time are inferior compared to the other examples. Furthermore, the curing agent composition of Comparative Example 1 contains (E) silica and (F) barium sulfate, which causes separation of the liquid surface (color floating / color separation), known as Benard cells, which impairs the appearance of the liquid surface of the composition and results in poor stability over time. The base composition of Comparative Example 2 contains (B) a carboxyl group-containing resin and (C) a photopolymerization initiator, and since it contains both of these, the detailed mechanism is unknown, but it is found that the dispersion degree (over time) and the stability of the appearance of the composition over time are inferior compared to each of the Examples, and furthermore, since it contains (E) silica and (F) barium sulfate, so-called Benard cells are generated, and it is found that the dispersion degree (over time) and the stability of the appearance of the composition over time are inferior compared to each of the Examples. The base composition of Comparative Example 3 did not contain (E) silica, and the hardener composition did not contain (E) silica but only (F) barium sulfate; that is, both components were not used in a single composition. Furthermore, the base composition did not contain (B) carboxyl group-containing resin or (C) photopolymerization initiator, so there were no problems with dispersion (over time) or stability of the composition's appearance over time. However, because neither the base composition nor the hardener composition of Comparative Example 3 contained the essential component (E) silica, cissing and pinholes occurred when forming a dry film from the mixture. Therefore, it was clear that Comparative Example 3 had poor electrical properties, so this evaluation was not performed. As described above, the base composition and hardener composition of Comparative Examples 1 and 2 have problems with the combination of each component, which causes poor appearance and the generation of coarse particles over time, and the photocurable thermosetting resin compositions of each Comparative Example, which are mixtures of these, are clearly inferior to the Examples in terms of evaluation of cissing and other issues when forming dry films, as well as in electrical properties.

Claims

1. A photocurable thermosetting resin composition comprising (A) an epoxy resin, (B) a carboxyl group-containing resin, (C) a photopolymerization initiator, (D) a photosensitive monomer, (E) silica, (F) barium sulfate, and an organic solvent, To obtain the photocurable thermosetting resin composition, at least a two-component resin composition is prepared, the (B) carboxyl group-containing resin, the (D) photosensitive monomer, and the (E) silica are contained in a resin composition separate from the (A) epoxy resin, the (F) barium sulfate, and the (C) photopolymerization initiator; The resin composition containing the (C) photopolymerization initiator is characterized in containing an organic solvent capable of dissolving the (C) photopolymerization initiator. A photocurable thermosetting resin composition which is formulated into at least a two-component resin composition.

2. 2. The photocurable thermosetting resin composition according to claim 1, wherein the epoxy resin (A) contains three types of epoxy resins: a semi-solid or solid epoxy resin at room temperature, a biphenyl-type epoxy resin, and a novolac-type epoxy resin.

3. 3. The photocurable thermosetting resin composition according to claim 1, wherein the resin composition containing the epoxy resin (A) has a viscosity of 4 dPa s or less, and the photocurable thermosetting resin composition obtained by mixing the respective resin compositions has a viscosity of 4 dPa s or less.

4. 4. The photocurable thermosetting resin composition according to claim 1, wherein the resin composition containing the epoxy resin (A) contains the photopolymerization initiator (C) and the organic solvent, and the organic solvent is contained in an amount of 3 parts by mass or more per part by mass of the photopolymerization initiator (C).

5. A dry film having a thickness of 10 μm to 30 μm, obtained by applying the photocurable thermosetting resin composition according to any one of claims 1 to 4 to a carrier film and drying the applied film.

6. A cured product obtained by curing the photocurable thermosetting resin composition according to any one of claims 1 to 4.

7. A cured product obtained by curing the resin layer of the dry film according to claim 5.

8. An electronic part comprising the cured product according to claim 6 or 7.

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