Curable resin composition, dry film, cured product, and electronic component

Abstract

To provide a curable resin composition capable of preventing a development residue from occurring on the surface of a circuit board, preventing an undercut from occurring in a deep portion of the pattern of a formed cured product and forming the pattern of the cured product, and a dry film.SOLUTION: A curable resin composition used for a method for forming the pattern of a cured product on a circuit board includes an alkali soluble resin, a photoinitiator, an inorganic filler and an epoxy resin. A method for form the pattern of the cured product comprises: forming the dry coating film of the curable resin composition on the circuit board; pattern exposure treatment to the dry coating film; development treatment by an alkaline water solution; and cleaning treatment by an acidic aqueous solution in this order.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a curable resin composition and a dry film, and further to a cured product using the same and an electronic component having the cured product. [Background technology]

[0002] In recent years, with the demand for miniaturization and multifunctionality of electronic components, the circuits of the circuit boards included in the electronic components have been increasingly miniaturized. To form a pattern of a cured product on such a circuit board, an alkali-developable composition is used as an insulating material. Conventional alkali-developable compositions contain a wide variety of components, for example, resin components such as epoxy resins and additives such as colorants.

[0003] In addition, an alkali-developable composition is used to form a pattern of a cured product on a circuit board by applying it to a circuit board, exposing it to light in a pattern, and then developing it with an alkaline aqueous solution to remove unnecessary parts (unexposed parts).

[0004] For example, Patent Document 1 discloses that a black curable resin composition containing a carboxyl group-containing photosensitive resin, a photopolymerization initiator, a diluent, an epoxy compound, and a black colorant has excellent resolution, is easy to adjust to a black color, and can prevent color change after heat treatment. Furthermore, Patent Document 1 discloses that when evaluating resolution, the black curable resin composition is applied to a circuit board, dried, exposed to light, and then developed with an aqueous sodium carbonate solution. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-257711 DISCLOSURE OF THE INVENTION [Problem to be solved by the invention]

[0006] The black curable resin composition (alkali-developable composition) disclosed in Patent Document 1 may contain an inorganic filler (extender pigment) in addition to an epoxy compound and a black colorant. Such a complex component composition raises the risk of generating development residues on the surface of the circuit board due to the resin components and inorganic filler during development with an alkaline aqueous solution after patterning exposure. With the miniaturization of recent circuit boards, even minute development residues can cause defects in electronic components, so countermeasures are necessary.

[0007] When the components in the composition are reduced or the alkaline developer is changed in order to suppress this development residue, the deep portion of the cured product pattern on the circuit board side becomes more susceptible to dissolution in the alkaline developer, which may cause undercuts and shape abnormalities in the cured product pattern.Furthermore, there have been cases where development residues are generated while undercuts are occurring in the cured product pattern. As circuits become increasingly miniaturized, even slight irregularities in the shape of the cured product pattern can reduce the gold plating resistance and cause defects in electronic components, so measures to prevent this are necessary.

[0008] Therefore, an object of the present invention is to provide a curable resin composition and a dry film that are capable of forming a pattern of a cured product, which are unlikely to generate development residues on the surface of a circuit board and are unlikely to generate undercuts deep on the substrate side in the pattern of the formed cured product. [Means for solving the problem]

[0009] As a result of intensive research aimed at achieving the above object, the present inventors have found that the above problems can be solved by using a curable resin composition and a dry film having a specific composition in a specific pattern formation method that includes patterning exposure, development treatment with an alkaline aqueous solution, and then a cleaning treatment with an acidic aqueous solution, and have thus completed the present invention.

[0010] The present invention (1) is A curable resin composition used in a method for forming a pattern of a cured product on a circuit board, comprising: the curable resin composition contains an alkali-soluble resin, a photopolymerization initiator, an inorganic filler, and an epoxy resin; The method for forming a pattern of the cured product comprises forming a dried coating film of the curable resin composition on a circuit board, followed by a pattern exposure treatment of the dried coating film, a development treatment with an alkaline aqueous solution, and a washing treatment with an acidic aqueous solution, in the order of the treatments. The present invention (2) is The curable resin composition of the invention (1) is characterized in that the blending amount of the inorganic filler is 40 to 130 parts by mass with respect to 100 parts by mass of the alkali-soluble resin. The present invention (3) is The curable resin composition of the invention (1) or (2) is characterized in that the amount of the epoxy resin blended is 30 to 70 parts by mass per 100 parts by mass of the alkali-soluble resin. The present invention (4) is A dry film used in a method for forming a pattern of a cured product on a circuit board, comprising: the dry film has a resin layer obtained by applying a curable resin composition containing an alkali-soluble resin, a photopolymerization initiator, an inorganic filler, and an epoxy resin to a support; The method for forming a pattern of the cured product is characterized by including, after laminating a resin layer of the dry film on a circuit board, a pattern exposure treatment of the resin layer, a development treatment with an alkaline aqueous solution, and a cleaning treatment with an acidic aqueous solution, in the order of the treatments mentioned above. The present invention (5) is In the dry film of the invention (4), the inorganic filler is mixed in an amount of 40 to 130 parts by mass with respect to 100 parts by mass of the carboxyl group-containing resin. The present invention (6) is The hard dry film of the invention (4) or (5) is characterized in that the amount of the epoxy resin blended is 30 to 70 parts by mass with respect to 100 parts by mass of the carboxyl group-containing resin. The present invention (7) is The curable resin composition is a cured product obtained by curing the resin layer of the curable resin composition of any one of the inventions (1) to (3) or the dry film of any one of the inventions (4) to (6). The present invention (8) is An electronic part comprising the cured product of the invention (7). [Effects of the Invention]

[0011] According to the present invention, it is possible to provide a curable resin composition and a dry film that are capable of forming a pattern of a cured product, which are unlikely to produce development residues on the surface of a circuit board that has been subjected to a pattern exposure treatment, a development treatment with an alkaline aqueous solution, and a cleaning treatment with an acidic aqueous solution after forming a dry coating film or a resin layer on the circuit board, and which are unlikely to produce undercuts deep in the pattern of the formed cured product. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a schematic diagram showing a method for measuring the amount of undercut in a cured product pattern. DETAILED DESCRIPTION OF THE INVENTION

[0013] The curable resin composition of the present invention will be described below, but the present invention is not limited to the following in any way.

[0014] When the compounds described have isomers, all possible isomers can be used in the present invention unless otherwise specified.

[0015] In this specification, the term "resin composition" may be used to mean a "curable resin composition."

[0016] In this specification, the term "(meth)acrylic" includes both "methacrylic" and "acrylic".

[0017] In this specification, when the upper and lower limits of a numerical range are separately stated, all combinations of each lower limit and each upper limit are considered to be substantially stated within a consistent range.

[0018] 1. Curable resin composition and dry film The curable resin composition of the present invention contains an alkali-soluble resin, a photopolymerization initiator, an inorganic filler, and an epoxy resin. The curable resin composition of the present invention may further contain other components as long as the effects of the present invention are not impaired.

[0019] The dry film of the present invention has a resin layer obtained from a curable resin composition containing an alkali-soluble resin, a photopolymerization initiator, an inorganic filler, and an epoxy resin, i.e., a resin layer obtained by applying the curable resin composition of the present invention to a support such as a PET film.

[0020] When a curable resin composition containing an alkali-soluble resin, a photopolymerization initiator, an inorganic filler, and an epoxy resin is used in a conventional pattern formation method using an alkaline aqueous solution, development residues tend to be generated on the surface of a circuit board, and undercuts tend to occur deep in the pattern of the formed cured product. In other words, it has been difficult to obtain a good pattern shape of the cured product while simultaneously suppressing both development residues and undercuts. However, by using the curable resin composition in a specific pattern formation method in which a development treatment with an alkaline aqueous solution is followed by a cleaning treatment with an acidic aqueous solution, development residues are less likely to be generated on the surface of a circuit board, and undercuts are less likely to occur in the pattern of the cured product. Therefore, a good pattern shape of the cured product can be obtained while simultaneously suppressing both development residues and undercuts. Note that the same effect can be achieved in a dry film having a resin layer obtained from the curable resin composition.

[0021] Each component of the curable resin composition will be described below. 1-1. Alkali-soluble resin The alkali-soluble resin according to the present invention is not particularly limited as long as the effects of the present invention are not impaired, but examples thereof include compounds having two or more phenolic hydroxyl groups, carboxyl group-containing resins, compounds having a phenolic hydroxyl group and a carboxyl group, and compounds having two or more thiol groups. Among these, carboxyl group-containing resins or phenolic resins are preferred because of their excellent adhesion to the substrate, and carboxyl group-containing resins are more preferred because of their excellent developability. The carboxyl group-containing resin may be a carboxyl group-containing photosensitive resin having an ethylenically unsaturated group, or a carboxyl group-containing resin without an ethylenically unsaturated group.

[0022] Specific examples of the carboxyl group-containing resin include the following compounds (which may be either oligomers or polymers):

[0023] (1) Copolymerization of unsaturated carboxylic acids such as (meth)acrylic acid with unsaturated group-containing compounds such as styrene, α-methylstyrene, lower alkyl (meth)acrylate, and isobutylene. A carboxyl group-containing resin obtained by

[0024] (2) 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 carboxyl group-containing dialcohol compounds such as dimethylolpropionic acid and dimethylolbutanoic acid, and diol compounds such as 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.

[0025] (3) Terminal carboxyl group-containing urethane resins obtained by reacting acid anhydrides with the terminals of urethane resins obtained by polyaddition reaction of diisocyanate compounds such as aliphatic diisocyanates, branched aliphatic diisocyanates, alicyclic diisocyanates, and aromatic diisocyanates with diol compounds such as 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.

[0026] (4) Carboxyl group-containing urethane resins obtained by the polyaddition reaction of diisocyanates with (meth)acrylates of bifunctional epoxy resins such as bisphenol A type epoxy resins, hydrogenated bisphenol A type epoxy resins, bisphenol F type epoxy resins, bisphenol S type epoxy resins, bixylenol type epoxy resins, and biphenol type epoxy resins, or their partially acid anhydride-modified products, carboxyl group-containing dialcohol compounds, and diol compounds.

[0027] (5) A carboxyl group-containing 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 a hydroxyalkyl (meth)acrylate, during the synthesis of the resin (2) or (4).

[0028] (6) A carboxyl group-containing urethane resin that is (meth)acrylated at the terminal 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 (2) or (4).

[0029] (7) A carboxyl group-containing resin obtained by reacting a multifunctional epoxy resin with (meth)acrylic acid and adding a dibasic acid anhydride such as phthalic anhydride, tetrahydrophthalic anhydride, or hexahydrophthalic anhydride to the hydroxyl groups present in the side chains.

[0030] (8) A carboxyl group-containing resin obtained by reacting a polyfunctional epoxy resin in which the hydroxyl groups of a difunctional epoxy resin have been further epoxidized with epichlorohydrin with (meth)acrylic acid, and then adding a dibasic acid anhydride to the resulting hydroxyl groups.

[0031] (9) Dicarboxylic acid is reacted with polyfunctional oxetane resin, and dibasic groups are added to the resulting primary hydroxyl groups. A polyester resin containing carboxyl groups to which acid anhydrides have been added.

[0032] (10) A carboxyl group-containing resin obtained by reacting a compound having multiple phenolic hydroxyl groups in one molecule with an alkylene oxide such as ethylene oxide or propylene oxide, reacting the resulting reaction product with an unsaturated group-containing monocarboxylic acid, and then reacting the resulting reaction product with a polybasic acid anhydride.

[0033] (11) A carboxyl group-containing 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.

[0034] (12) A carboxyl group-containing resin obtained by reacting an epoxy compound having multiple epoxy groups in one molecule with a compound having at least one alcoholic hydroxyl group and one phenolic hydroxyl group in one molecule, such as p-hydroxyphenethyl alcohol, and an unsaturated group-containing monocarboxylic acid, such as (meth)acrylic acid, and then reacting the alcoholic hydroxyl groups of the resulting reaction product with a polybasic acid anhydride, such as maleic anhydride, tetrahydrophthalic anhydride, trimellitic anhydride, pyromellitic anhydride, or adipic anhydride.

[0035] (13) A carboxyl group-containing resin obtained by further adding a compound having one epoxy group and one or more (meth)acryloyl groups in the molecule, such as glycidyl (meth)acrylate, α-methylglycidyl (meth)acrylate, etc., to the carboxyl group-containing resin described in (1) to (12) above.

[0036] Among the carboxyl group-containing resins, it is preferable to include at least one of the carboxyl group-containing resins (7), (8), (10), (11), and (13), and from the viewpoint of further improving the insulation reliability, it is more preferable to include the carboxyl group-containing resin described in (10) or (11).

[0037] The acid value of the alkali-soluble resin is not particularly limited as long as it does not impair the effects of the present invention, but is, for example, 40 to 200 mgKOH / g, preferably 45 to 120 mgKOH / g. When the acid value of the alkali-soluble resin is within this range, development of the coating film or resin layer with an aqueous alkaline solution after exposure becomes easy, and it becomes easy to draw a normal cured product pattern.

[0038] The weight-average molecular weight of the alkali-soluble resin varies depending on the resin skeleton, but can be 1,500 to 150,000, preferably 1,500 to 100,000, more preferably 1,500 to 50,000, and particularly preferably 1,500 to 30,000. When the weight-average molecular weight is within this range, a curable resin composition and a dry film can be obtained that are excellent in tack-free performance, storage stability, moisture resistance of the coating film and resin layer after exposure, and developability, and that can suppress film loss during development and a decrease in resolution.

[0039] The alkali-soluble resins can be used alone or in combination.

[0040] 1-2. Photopolymerization initiator The photopolymerization initiator according to the present invention is not particularly limited as long as the effect of the present invention is not impaired, and any photopolymerization initiator known as a photopolymerization initiator or photoradical generator can be used.

[0041] Examples of the photopolymerization initiator include bisacylphosphine oxides such as 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, bis-(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide, bis-(2,6-dimethoxybenzoyl)-2,5-dimethylphenylphosphine oxide, and bis-(2,4,6-trimethylbenzoyl)-phenylphosphine oxide; monoacylphosphine oxides such as 2,6-dimethoxybenzoyldiphenylphosphine oxide, 2,6-dichlorobenzoyldiphenylphosphine oxide, 2,4,6-trimethylbenzoylphenylphosphinic acid methyl ester, 2-methylbenzoyldiphenylphosphine oxide, pivaloylphenylphosphinic acid isopropyl ester, and 2,4,6-trimethylbenzoyldiphenylphosphine oxide; hydroxyacetophenones such as 1-hydroxycyclohexylphenyl 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-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; Acetophenones such as 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, and N,N-dimethylaminoacetophenone; thioxanthones such as thioxanthone, 2-ethylthioxanthone, 2-isopropylthioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2-chlorothioxanthone, and 2,4-diisopropylthioxanthone; anthraquinones such as anthraquinone, chloroanthraquinone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-tert-butylanthraquinone, 1-chloroanthraquinone, 2-amylanthraquinone, 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; Oxime esters such as 1,2-octanedione, 1-[4-(phenylthio)-, 2-(O-benzoyloxime)], ethanone, 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]-, 1-(O-acetyloxime); Titanocenes such as bis(η5-2,4-cyclopentadien-1-yl)-bis(2,6-difluoro)-3-(1H-pyrrol-1-yl)phenyl)titanium and bis(cyclopentadienyl)-bis[2,6-difluoro-3-(2-(1-pyr-1-yl)ethyl)phenyl]titanium; Examples of such compounds include phenyl disulfide 2-nitrofluorene, butyroin, anisoin ethyl ether, azobisisobutyronitrile, tetramethylthiuram disulfide, etc. These compounds may be used alone or in combination.

[0042] The amount of the photopolymerization initiator is not particularly limited as long as it does not impair the effects of the present invention, but is preferably 0.5 to 20 parts by mass per 100 parts by mass of the alkali-soluble resin. When the amount of the photopolymerization initiator is within this range, a curable resin composition and a dry film having excellent surface curability, little halation, and good resolution can be obtained.

[0043] 1-3.Inorganic filler The inorganic filler according to the present invention is not particularly limited as long as it does not impair the effects of the present invention, and examples thereof include inorganic fillers such as silica, crystalline silica, Neuburg silica, aluminum hydroxide, glass powder, talc, clay, magnesium carbonate, calcium carbonate, natural mica, synthetic mica, aluminum hydroxide, barium sulfate, barium titanate, iron oxide, non-fibrous glass, hydrotalcite, mineral wool, aluminum silicate, calcium silicate, and zinc oxide. These may be used alone or in combination. Among these, it is preferable to include at least one of silica and barium sulfate, as this improves the heat resistance and mechanical properties of the cured product.

[0044] The average particle size of the inorganic filler is not particularly limited as long as it does not impair the effects of the present invention, but the upper limit can be 10 μm or less, or 3 μm or less. The lower limit can be 0.01 μm or more, or 0.05 μm or more. The average particle size of the inorganic filler can be, for example, the D50 value measured by laser diffraction. Here, the average particle size of the inorganic filler is the average particle size (D50) including not only the particle size of primary particles but also the particle size of secondary particles (aggregates), and can be determined using a laser diffraction particle size distribution analyzer and a measuring device using dynamic light scattering. Examples of measuring devices using laser diffraction include the Microtrac MT3300EXII manufactured by Microtrac-Bell, and examples of measuring devices using dynamic light scattering include the Nanotrac Wave II UT151 manufactured by Microtrac-Bell. When the average particle size of the inorganic filler is within this range, diffuse reflection of light irradiation during exposure can be suppressed, facilitating fine processing of the cured product pattern.

[0045] The inorganic filler may be one that has been subjected to a surface treatment, or one that has been subjected to a surface treatment that allows a curable reactive group to be introduced onto the surface thereof. Here, the curable reactive group refers to a group that undergoes a curing reaction with a carboxyl group-containing resin, an epoxy resin, etc., 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, while 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 onto the surface of the inorganic filler 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 that can be used 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 subjected to silica-alumina surface treatment, titanate-based coupling agent treatment, aluminate-based coupling agent treatment, and organic treatment.

[0046] The amount of inorganic filler blended is preferably 40 to 130 parts by mass, more preferably 70 to 110 parts by mass, per 100 parts by mass of the alkali-soluble resin. When the amount is within the range of 55 to 85 parts by mass, development residue and undercut are further suppressed, and a cured product with excellent gold plating resistance can be obtained.

[0047] 1-4.Epoxy resin The epoxy resin according to the present invention is not particularly limited as long as it does not impair the effects of the present invention, and liquid, semi-solid, and solid epoxy resins can be used. From the viewpoint of gold plating resistance, it is preferable to contain a solid epoxy resin and a semi-solid epoxy resin. In this specification, "solid epoxy resin" refers to an epoxy resin that is solid at 40°C, "semi-solid epoxy resin" refers to an epoxy resin that is solid at 20°C and liquid at 40°C, and "liquid epoxy resin" refers to an epoxy resin that is liquid at 20°C. The liquid state is 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). For example, this can be done using the method described in paragraphs 23 to 25 of JP 2016-079384 A.

[0048] Examples of epoxy resins include bisphenol A type epoxy resins; brominated epoxy resins; novolac type epoxy resins; bisphenol F type epoxy resins; hydrogenated bisphenol A type epoxy resins; biphenyl type epoxy resins; glycidylamine type epoxy resins; hydantoin type epoxy resins; alicyclic epoxy resins; triphenylmethane type epoxy resins; trihydroxyphenylmethane type epoxy resins; bixylenol type or biphenol type epoxy resins, or mixtures thereof; bisphenol S type epoxy resins; bisphenol A novolac type epoxy resins; tetraphenylolethane type epoxy resins; heterocyclic epoxy resins; diglycidyl phthalate resins; tetraglycidylxylenoylethane resins; naphthalene group-containing epoxy resins; epoxy resins having a dicyclopentadiene skeleton; epoxy resins having a silsesquioxane skeleton; glycidyl (meth)acrylate copolymer epoxy resins; cyclohexylmaleimide and glycidyl (meth)acrylate copolymer epoxy resins; epoxy-modified polybutadiene rubber derivatives; and CTBN-modified epoxy resins. These may be used alone or in combination.

[0049] Among these, epoxy resins having a dicyclopentadiene skeleton are preferred in terms of improving the resolution of the curable resin composition of the present invention and the dry film, since they have an alicyclic skeleton. Also, biphenyl-type epoxy resins and novolac-type epoxy resins are preferred in terms of improving the heat resistance of the curable resin composition of the present invention and the dry film, since they have an aromatic ring skeleton.

[0050] The epoxy equivalent of the epoxy resin is not particularly limited as long as the effects of the present invention are not impaired, but can be, for example, 150 g / eq. or more, preferably 200 g / eq. or more. When the epoxy equivalent of the epoxy resin is within this range, it is possible to obtain a curable resin composition and a dry film that can form a cured product that has excellent insulation reliability and adhesion even when covering a fine circuit pattern. Here, the epoxy equivalent is the value of each epoxy resin contained in the curable resin composition or dry film of the present invention.

[0051] The amount of epoxy resin blended is not particularly limited as long as it does not impair the effects of the present invention, but for example, it is preferably 30 to 70 parts by mass, more preferably 45 to 70 parts by mass, and even more preferably 45 to 55 parts by mass, per 100 parts by mass of alkali-soluble resin. 45 to 70 parts by mass allows for the production of a cured product with even better gold plating resistance. 45 to 55 parts by mass further suppresses development residue and undercut, allowing for the production of a cured product with even better gold plating resistance.

[0052] 1-5.Photosensitive Monomer The curable resin composition of the present invention may contain a known and commonly used photosensitive monomer. The photosensitive monomer is, for example, a compound having one or more ethylenically unsaturated groups in the molecule. Such a photosensitive monomer cures the composition upon irradiation with active energy rays. The photosensitive monomer 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,Diacrylates of diols 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, diacrylates of diols 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, diacrylates of EO adducts of bisphenol A, diacrylates of PO adducts of bisphenol A, diacrylates having a cyclic structure such as tricyclodecane dimethanol diacrylate, hydrogenated dicyclopentadienyl diacrylate and cyclohexyl diacrylate, or methacrylate monomers corresponding thereto. Examples of suitable acrylates include polyfunctional acrylates such as bifunctional (meth)acrylates, 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 acrylates, 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 acrylates. The content of such a photosensitive monomer is preferably in the range of 10 to 70 parts by mass relative to 100 parts by mass of the alkali-soluble resin. When the amount of the photosensitive monomer is within this range, the curable resin composition has sufficient photocurability and good tackiness (dryness to the touch).

[0053] 1-6.Thermosetting catalyst Since the curable resin composition contains an epoxy resin, it preferably contains a thermosetting catalyst. Examples of the thermosetting catalyst include imidazole derivatives such as imidazole, 2-methylimidazole, 2-ethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 4-phenylimidazole, 1-cyanoethyl-2-phenylimidazole, and 1-(2-cyanoethyl)-2-ethyl-4-methylimidazole; amine compounds such as dicyandiamide, benzyldimethylamine, 4-(dimethylamino)-N,N-dimethylbenzylamine, 4-methoxy-N,N-dimethylbenzylamine, and 4-methyl-N,N-dimethylbenzylamine; hydrazine compounds such as adipic acid dihydrazide and sebacic acid dihydrazide; and phosphorus compounds such as triphenylphosphine. Commercially available catalysts include, for example, 2MZ-A, 2MZ-OK, 2PHZ, 2P4BHZ, and 2P4MHZ (all trade names of imidazole-based compounds) manufactured by Shikoku Chemicals Corporation, and U-CAT (registered trademark) 3503N and U-CAT3502T (all trade names of dimethylamine-blocked isocyanate compounds), DBU, DBN, U-CATSA102, and U-CAT5002 (all bicyclic amidine compounds and salts thereof) manufactured by San-Apro Co., Ltd. However, the catalyst is not limited to these, and any catalyst that is a heat curing catalyst for epoxy resins or that promotes the reaction between epoxy groups and carboxyl groups may be used, and they may be used alone or in combination of two or more. Alternatively, S-triazine derivatives such as guanamine, acetoguanamine, benzoguanamine, melamine, 2,4-diamino-6-methacryloyloxyethyl-S-triazine, 2-vinyl-2,4-diamino-S-triazine, 2-vinyl-4,6-diamino-S-triazine·isocyanuric acid adduct, and 2,4-diamino-6-methacryloyloxyethyl-S-triazine·isocyanuric acid adduct can also be used, and these compounds that also function as adhesion promoters are preferably used in combination with the heat curing catalyst. When a thermosetting catalyst is blended into a curable resin composition, the blending amount is sufficient in a ratio that is usually used, for example, 0.01 to 15 parts by mass per 100 parts by mass of the epoxy resin.

[0054] 1-7.Coloring agents The curable resin composition may contain a colorant. As the colorant, any of commonly used and known colorants such as red, blue, green, and yellow may be used, and any of pigments, dyes, and coloring matters may be used. The colorant can be blended arbitrarily depending on the purpose, and when a colorant is blended, the blending amount of the colorant is, for example, 0.01 to 5 mass % relative to the total amount of solids in the curable resin composition.

[0055] 1-8.Other ingredients The curable resin composition of the present invention may contain other components commonly known and commonly used in the field of electronic materials. Examples of such components include photocurable compounds and thermosetting compounds other than the alkali-soluble resins and epoxy resins described above; organic solvents; polymerization inhibitors; UV absorbers; silane coupling agents; plasticizers; flame retardants; antistatic agents; antioxidants; antioxidants; antibacterial and antifungal agents; defoaming agents; leveling agents; thickeners; adhesion promoters; thixotropy-imparting agents; photoinitiator assistants; sensitizers; photobase generators; thermoplastic resins; elastomers; organic fillers; release agents; surface treatment agents; dispersants; dispersion assistants; surface modifiers; stabilizers; and phosphors. These components may be used alone or in combination.

[0056] 2. Dry film manufacturing method The dry film of the present invention has a resin layer obtained by applying the curable resin composition of the present invention to a support and then drying it. The dry film of the present invention can be obtained by diluting the curable resin composition of the present invention with an organic solvent to adjust the viscosity appropriately, applying the composition to a uniform thickness on a support using a comma coater, blade coater, lip coater, rod coater, squeeze coater, reverse coater, transfer roll coater, gravure coater, spray coater, or the like, and drying it at a temperature of 50 to 130°C for 1 to 30 minutes. There are no particular restrictions on the coating thickness, but the thickness after drying can generally be set appropriately within the range of 3 to 100 μm, preferably 5 to 40 μm.

[0057] As the support, a plastic film can be suitably used, and it is preferable to use a plastic film such as a polyester film such as polyethylene terephthalate, a polyimide film, a polyamideimide film, a polypropylene film, a polystyrene film, etc. The thickness of the support is not particularly limited, but can generally be in the range of 10 to 150 μm.

[0058] After the curable resin composition of the present invention is applied to a support and dried, a peelable film (hereinafter also referred to as a "cover film") may be laminated on the surface of the coating film for the purpose of preventing dust from adhering to the surface of the coating film, etc. Examples of the peelable cover film that can be used include polyethylene film, polytetrafluoroethylene film, polypropylene film, and surface-treated paper, and any film may be used as long as the adhesive strength between the resin layer and the cover film is smaller than the adhesive strength between the resin layer and the support when the cover film is peeled off.

[0059] The drying treatment carried out after the curable resin composition of the present invention is applied onto a support can be carried out using a hot air circulation drying oven, an IR oven, a hot plate, a convection oven, or the like.

[0060] 3. Circuit board manufacturing method (use of curable resin composition and dry film) The electronic component of the present invention has a cured product obtained from the curable resin composition of the present invention or a resin layer of a dry film. The method for producing an electronic component of the present invention is characterized in that the method for forming a pattern on the cured product includes forming a dried coating film of the curable resin composition on a circuit board, followed by a pattern exposure treatment of the dried coating film, a development treatment with an alkaline aqueous solution, and a cleaning treatment with an acidic aqueous solution, in the order of the treatments mentioned above. That is, after forming a dried coating film or resin layer on a circuit board, other treatments may be performed before or after each of the treatments, as long as the order of the pattern exposure treatment, development treatment with an alkaline aqueous solution, and cleaning treatment with an acidic aqueous solution is maintained. The other treatments may be treatments known in the manufacture of circuit boards and are not particularly limited. For example, a rinse treatment with pure water or a heat treatment may be performed after the cleaning treatment with an acidic aqueous solution. Here, it is preferable that the development treatment with an alkaline aqueous solution and the cleaning treatment with an acidic aqueous solution are performed consecutively.

[0061] The method for producing an electronic component using the curable resin composition and the dry film of the present invention will be described below. As a method for forming a dry coating film using the curable resin composition of the present invention, for example, the viscosity of the curable resin composition of the present invention is adjusted using the organic solvent to be suitable for the coating method, and the composition is applied to a circuit board by a method such as dip coating, flow coating, roll coating, bar coating, screen printing, or curtain coating, and then the organic solvent contained in the composition is evaporated and dried (pre-dried) at a temperature of 60 to 100°C, thereby forming a tack-free dry coating film.

[0062] A method for laminating a resin layer on a circuit board using the dry film of the present invention can be, for example, by using a laminator or the like to attach the dry film to the circuit board so that the resin layer of the dry film comes into contact with the circuit board, and then peeling off the support, thereby laminating (forming) the resin layer on the circuit board.

[0063] Examples of circuit boards include printed wiring boards and flexible printed wiring boards with pre-formed circuits made of copper or other materials, as well as copper-clad laminates for high-frequency circuits made of 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, and polyphenylene oxide / cyanate, including all grades of copper-clad laminates (e.g., FR-4), as well as metal substrates, polyimide film, PET film, polyethylene naphthalate (PEN) film, glass substrates, ceramic substrates, and wafer plates. The circuits may be pretreated, for example, with GliCAP (manufactured by Shikoku Kasei), New Organic AP (Adhesion Promoter) (manufactured by MEC), or Nova Bond (manufactured by Atotech Japan) to improve adhesion to cured coatings such as solder resist, or with a rust inhibitor.

[0064] The volatilization drying carried out after application of the curable resin composition of the present invention can be carried out using a hot air circulation drying oven, an IR oven, a hot plate, a convection oven, or the like (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).

[0065] In the pattern exposure treatment, for example, after forming a resin layer on a circuit board, the resin layer can be selectively exposed to active energy rays through a photomask on which a predetermined pattern has been formed.

[0066] The exposure device used for actinic 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 actinic energy rays in the range of 350 to 450 nm. Furthermore, a direct imaging device (for example, a laser direct imaging device that directly draws an image with a laser based on CAD data from a computer) may also be used. The lamp light source or laser light source of the direct imaging device may have a maximum wavelength in the range of 350 to 450 nm. The exposure dose for image formation varies depending on factors such as the film thickness, but is generally 10 to 1,000 mJ / cm. 2 , preferably 20 to 800 mJ / cm 2 The range may be:

[0067] In the development treatment with an alkaline aqueous solution, for example, the unexposed areas after the patterned exposure treatment are developed with a dilute alkaline aqueous solution (for example, a 0.3 to 3 mass % aqueous sodium carbonate or potassium carbonate solution) to form a pattern in a cured product.

[0068] The development treatment with an alkaline aqueous solution can be carried out by a dipping method, a shower method, a spray method, a brush method, etc., and the developer can be an aqueous alkaline solution of potassium hydroxide, sodium hydroxide, sodium carbonate, potassium carbonate, sodium phosphate, sodium silicate, ammonia, amines, etc. These may be used in combination.

[0069] In the cleaning treatment with an acidic aqueous solution, for example, after development treatment with an alkaline aqueous solution, the patterned cured product is cleaned with an acidic aqueous solution (for example, a 0.3 to 3 volume % sulfuric acid aqueous solution, acetic acid aqueous solution, a 0.3 to 3 mass % citric acid aqueous solution, or carbonated water adjusted to pH 5 by dissolving carbon dioxide gas in pure water).

[0070] The cleaning treatment with an acidic aqueous solution can be performed by dipping, showering, spraying, brushing, etc. The cleaning solution is not particularly limited as long as it is an acidic aqueous solution, but examples of inorganic acid aqueous solutions include aqueous solutions of sulfuric acid, sulfurous acid, hydrochloric acid, nitric acid, nitrous acid, carbonic acid, phosphoric acid, boric acid, and hydrogen peroxide. Examples of organic acid aqueous solutions include carboxylic acids such as lactic acid, malic acid, citric acid, benzoic acid, phthalic acid, isophthalic acid, terephthalic acid, salicylic acid, gallic acid, mellitic acid, cinnamic acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, fumaric acid, maleic acid, and aconitic acid; phosphonic acid; sulfonic acid; and acetic acid. These may be used in combination.

[0071] The concentration of the acidic aqueous solution is not particularly limited as long as it does not impair the effects of the present invention, but for example, the concentration of the acid in the aqueous solution is 0.5% by mass or more and 5% by mass or less. When the concentration of the acidic aqueous solution is in this range, the stability of the pattern of the cured product is excellent.

[0072] The treatment time in the cleaning treatment with an acidic aqueous solution is not particularly limited, and can be determined depending on the composition and concentration of the acidic aqueous solution, the cleaning treatment method (for example, dipping method or shower method), the type of circuit board, the metal used, etc. The treatment time can be, for example, 10 to 60 seconds, and preferably 10 to 30 seconds.

[0073] The temperature of the acidic aqueous solution used in the cleaning treatment with the acidic aqueous solution is not particularly limited, and can be determined depending on the composition and concentration of the acidic aqueous solution, the cleaning treatment method (for example, dipping method or shower method), the type of circuit board, the metal used, etc. The temperature of the acidic aqueous solution can be, for example, 0 to 50°C, and preferably 20 to 30°C.

[0074] After washing with an acidic aqueous solution, the cured product is irradiated with active energy rays and then heat-cured (for example, at 100 to 220°C), or is heat-cured and then irradiated with active energy rays, or is heat-cured alone to form a final finish curing (main curing) to form a cured film with excellent properties such as adhesion and hardness.

[0075] The curable resin composition and dry film of the present invention are suitable for forming a cured film on a circuit board, more preferably for forming a permanent coating, and even more preferably for forming a solder resist, an interlayer insulating layer, or a coverlay. They are also suitable for forming printed wiring boards with fine wiring patterns that require high reliability, such as permanent coatings (especially solder resists) for package substrates, especially FC-BGAs. For example, they can be used even when the L / S ratio is 10 / 10 or less, i.e., when the line width L is 10 μm or less and the line spacing is 10 μm or less, which is a fine pitch. The curable resin composition and dry film of the present invention can also be used for printed wiring boards with wiring patterns, even when the circuit surface has a small roughness, such as a high-frequency printed wiring board. For example, they can be used even when the surface roughness Ra is 0.5 μm or less, especially 0.3 μm or less. [Example]

[0076] EXAMPLES Next, the present invention will be described in detail with reference to examples and comparative examples, but the present invention is not limited to these examples at all.

[0077] <<<Preparation of curable resin composition>>> The procedures for preparing each resin composition (compositions of Examples 1 to 12 and Comparative Examples 1 to 5) will be described below.

[0078] <<Resin synthesis>> <Synthesis Example 1: Synthesis of alkali-soluble resin A-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%. 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. Then, 8 parts of oxalic acid was added, and the reaction was carried out at 100°C for 10 hours. After the reaction was completed, distillate was removed under reduced pressure at 180°C and 50 mmHg, yielding 550 parts of novolak resin A. Furthermore, 130 parts of the 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 final concentration, after which it was cooled to room temperature. 3.3 parts of a 36% aqueous solution of hydrochloric acid was added to the reaction solution and mixed 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. 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, 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%. 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. The mixture was heated to 110°C, 45 parts of tetrahydrophthalic anhydride was added, and the mixture was reacted for 4 hours. After cooling, the mixture was removed. The alkali-soluble resin A-1 thus obtained had a nonvolatile content of 72% and a solid acid value of 65 mgKOH / g. The weight-average molecular weight of the alkali-soluble resin A-1 was 11,000.

[0079] <Synthesis Example 2: Synthesis of alkali-soluble resin A-2> Into an autoclave equipped with a thermometer, a nitrogen / alkylene oxide inlet, and a stirrer, 119.4 parts of cresol novolac resin (Shonol CRG-951 manufactured by Aica Kogyo, OH equivalent: 119.4), 1.19 parts of potassium hydroxide, and 119.4 parts of toluene were introduced, and the system was purged with nitrogen while stirring, and heated to a temperature of 125-132°C and 0-4.8 kg / cm. Next, 63.8 parts of propylene oxide were gradually added dropwise, and the temperature was raised to 125-132°C and 0-4.8 kg / cm. 2 The mixture was reacted at 400 K for 16 hours. After cooling to room temperature, 1.56 parts of 89% phosphoric acid was added to the reaction solution 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 mg KOH / g (307.9 g / eq.). This resulted in an average of 1.08 moles of propylene oxide being added per equivalent of phenolic hydroxyl groups. 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, and 12.6 parts of water were distilled off. The mixture was then cooled to room temperature, neutralized with 35.35 parts of 15% aqueous sodium hydroxide solution, and then washed with water. The toluene was then distilled off using an evaporator, replacing it with 118.1 parts of diethylene glycol monoethyl ether acetate, to obtain a novolac acrylate resin solution. 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. Air was blown in at a rate of 10 ml / min. While stirring, 60.8 parts of tetrahydrophthalic anhydride was gradually added. The mixture was reacted at 95-101°C for 6 hours, cooled, and then removed. In this way, alkali-soluble resin A-2 was obtained, which had a solids content of 65% and an acid value of 87.7 mgKOH / g. The weight-average molecular weight of alkali-soluble resin A-2 was 2,500.

[0080] <Synthesis Example 3: Synthesis of photosensitive monomer> 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%. 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. Then, 8 parts of oxalic acid was added, and the reaction was carried out at 100°C for 10 hours. After the reaction was completed, distillate was removed under reduced pressure at 180°C and 50 mmHg, yielding 550 parts of novolak resin A. Furthermore, 130 parts of the 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 final concentration, after which it was cooled to room temperature. 3.3 parts of a 36% aqueous solution of hydrochloric acid was added to the reaction solution and mixed 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. 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 air into it, heated to 115°C, and reacted for another 4 hours while distilling off the water produced by the reaction as an azeotrope with toluene. The reaction solution was then cooled to room temperature. The resulting reaction solution was washed with 5% aqueous NaCl, and the toluene was removed by vacuum distillation. Diethylene glycol monoethyl ether acetate was then added to obtain a photosensitive monomer solution with a solids content of 68%. The weight-average molecular weight of the photosensitive monomer was 8,000.

[0081] <<Preparation of Curable Resin Composition>> The various components shown in Tables 1 to 3 were blended in the proportions shown in the tables, premixed in a mixer, and then kneaded using a bead mill to prepare curable resin compositions for each Example and Comparative Example. The blend amounts in the tables are in parts by mass. The agitator conditions were a rotation speed of 800 rpm, a mixing time of 10 min, and a mixer blade diameter of 12 cm. The bead mill conditions were a conical K-8 (manufactured by Buhler) with zirconia beads (filling rate 88%), a rotation speed of 1000 rpm, a discharge rate of 20%, and a bead diameter of 0.65 mm.

[0082] <<<Evaluation>>> The curable resin compositions of the examples and comparative examples were evaluated as follows, and the results are shown in Tables 1 to 3.

[0083] <<Developability evaluation>> After preparing compositions according to the examples and comparative examples in Tables 1 to 3, they were applied to a PET film using an applicator with a 50 μm gap and dried (80°C, 20 minutes) to obtain a dry film having a resin layer on the PET film. This dry film was cut into a size of 10 cm length x 10 cm width, and a resin layer was laminated onto a copper-clad laminate (FR-4 substrate) to obtain a substrate with a resin layer. This substrate was treated with an alkaline aqueous solution from Tables 1 to 3 for 45 seconds, 60 seconds, or 90 seconds at a developer temperature of 30°C and a spray pressure of 0.2 MPa, and then immersed in an acidic aqueous solution at 25°C for 15 seconds and washed with water for 60 seconds to obtain a substrate for evaluation. The cured product layer on the surface of this substrate was examined under an optical microscope to check for development residues.In Comparative Examples 1 and 2, immersion in an acidic aqueous solution was not performed. ◎: Can be developed in 45 seconds. 〇:Can be developed in 60 seconds. △: Can be developed in 90 seconds. ×: Cannot be developed.

[0084] <<Undercut evaluation>> (1) Preparation of a substrate for evaluating the amount of undercut The compositions of the Examples and Comparative Examples were applied onto a PET film using an applicator with a gap of 50 μm, and then dried in a hot air circulation drying oven (80° C., 20 minutes) to obtain dry films. The resin layer of this dry film was thermocompression bonded to an FR-4 substrate using a laminating device to obtain a substrate having a resin layer. This substrate was exposed to light through a negative mask using a laser direct exposure machine (Oak Manufacturing Co., Ltd.: Mms 60, exposure dose 300 mJ / cm 2 ), and then using the alkaline aqueous solutions shown in Tables 1 to 3, the substrate was subjected to development at 30°C, spray pressure of 0.2 MPa, development time of 60 seconds, acid treatment at 25°C, acid treatment time of 15 seconds, and water washing time of 60 seconds, yielding a substrate with a cured product pattern of L / S: 300 μm. This was followed by UV irradiation (high-pressure mercury lamp: 1000 mJ / cm 2 ) and was subjected to full curing at 150°C for 60 minutes using a hot air circulation drying oven to prepare a substrate for cross-section evaluation. (2) Undercut measurement method The substrate obtained in (1) above was cut so that the cross section of the cured product pattern could be observed, embedded in resin, and polished using a polishing machine so that the cross section of the cured product pattern could be observed. Sandpaper grits of 600, 1000, and 2000 were used for polishing, and polishing was continued using 4000 grit sandpaper as needed until the cross section surface became observable. The cross section of the cured product pattern was observed using a scanning electron microscope to measure the amount of undercut (see Figure 1). This is the shortest distance between the reference line and the undercut line shown in Figure 1. Here, reference line X and undercut line Y are assumed to be in the same plane on the observed cross section surface. Reference line X is a line perpendicular to the substrate that passes through the intersection of a line drawn on the surface of the substrate along the side of the cured product pattern with the substrate (intersection A in Figure 1) when the cross section of the cured product pattern is viewed from the front. Undercut line Y is a line perpendicular to the substrate that passes through the intersection of the undercut edge of the cured product pattern with the substrate (intersection B in Figure 1). ◎: The average undercut amount (n=5) is 5 μm or less ○: The average undercut amount (n=5) is 6 μm or more and 10 μm or less △: The average amount of undercut (n=5) is between 11 μm and 15 μm ×: The average undercut amount (n=5) is 20 μm or more

[0085] <<Gold plating resistance evaluation>> Test substrates for evaluation were obtained in the same manner as in the preparation of the substrates for evaluating the amount of undercut described above. The obtained evaluation substrates were subjected to electroless gold plating under the conditions described below, and then the test substrates were subjected to a peeling test using cellophane adhesive tape to check for changes in appearance and the peeling state of the cured film. The evaluation criteria are as follows: ⊚: There was no change in the appearance of the evaluation substrate, and no peeling of the cured film was observed after the tape peeling test. ◯: The appearance of the evaluation substrate showed soaking of the plating solution, but no peeling of the cured film after the tape peeling test. △: The appearance of the evaluation board showed soaking of the plating solution, but partial peeling of the cured film was confirmed after the tape peeling test. ×: Significant lifting of the cured film and sinking of the plating were observed, and the peeling of the cured film was significant after the tape peeling test. <Electroless gold plating procedure> The evaluation substrate with the heat-cured cured product pattern was immersed in an acidic degreasing solution (20 vol% aqueous solution of Metex L-5B, manufactured by Japan MacDermid Co., Ltd.) at 30°C for 3 minutes, then rinsed with water, immersed in a 14.3 wt% aqueous solution of ammonium persulfate at room temperature for 3 minutes to perform soft etching, and then immersed in running water for 3 minutes and rinsed with water. The evaluation substrate was then immersed in a 10 vol% aqueous sulfuric acid solution at room temperature for 1 minute, then rinsed with running water, and further immersed in a catalyst solution (10 vol% aqueous solution of Metal Plate Activator 350, manufactured by Meltex) at 30°C for 3 minutes to apply a catalyst. After rinsing with running water, the evaluation substrate was immersed in water for 3 minutes. The evaluation substrate thus catalyst-applied was immersed in a nickel plating solution (20 vol% aqueous solution of Melplate Ni-865M, manufactured by Meltex) at 85°C for 20 minutes to perform electroless nickel plating, and then immersed in a 10 vol% aqueous sulfuric acid solution at room temperature for 1 minute, followed by immersion in running water for 1 minute to rinse. Next, the specimen was immersed in an 85°C gold plating solution (manufactured by Meltex, an aqueous solution of 10 vol% Melplate AU-6601MA, 10 vol% Melplate AU-6601 MB, and 3 wt% potassium gold cyanide) for 30 minutes to perform electroless gold plating, and then rinsed in 60°C warm water for 3 minutes. Finally, the substrate was washed with water and dried to obtain a sample for evaluating gold plating resistance, which had been electrolessly gold plated.

[0086] [Table 1] *1 Carbon black: MA-100 (Mitsubishi Chemical Corporation) *2 BYK-350 (manufactured by BYK Japan) *3 DPHA: Dipentaerythritol hexaacrylate (hexafunctional acrylic monomer, manufactured by Nippon Kayaku Co., Ltd.) *4 Laromer LR8863: EO-modified trimethylolpropane triacrylate (BASF Japan) *5 TPO: Acylphosphine oxide photopolymerization initiator (manufactured by IGM Resins BV) *6 JMT784: Titanocene photopolymerization initiator (manufactured by Yueyang Kimoutain Sci-tech Co. Ltd.) *7 Quinopower QS-30: Naphthoquinone polymerization inhibitor (Kawasaki Chemical Industries, Ltd.) *8 SiO2, average particle size: 0.5 μm, no surface treatment *9 PMA (Propylene Glycol Monomethyl Ether Acetate) *10 B-33: Barium sulfate (Sakai Chemical Industry Co., Ltd.) *11 CA (Carbitol Acetate) *12 Dicyclopentadiene epoxy resin (HP-7200L; manufactured by DIC Corporation) *13 Biphenylarafkyl epoxy resin (NC-3000H; Nippon Kayaku Co., Ltd.) *14 Bisphenol A novolac epoxy resin (N-870; manufactured by DIC Corporation) *15 Bisphenol A epoxy resin (jER834; Mitsubishi Chemical Corporation) [Table 2]

[0087] [Table 3]

Claims

1. A curable resin composition used in a method for forming a pattern of a cured product on a circuit board, comprising: the curable resin composition contains an alkali-soluble resin, a photopolymerization initiator, an inorganic filler, and an epoxy resin; The method for forming a pattern of the cured product comprises forming a dry coating film of the curable resin composition on a circuit board, followed by a pattern exposure treatment of the dry coating film, a development treatment with an alkaline aqueous solution, and a washing treatment with a 0.3 to 3 mass % aqueous citric acid solution or carbonated water prepared by dissolving carbon dioxide gas in pure water and adjusting the pH to 5, in the order of the treatments mentioned above.

2. 2. The curable resin composition according to claim 1, wherein the inorganic filler is blended in an amount of 40 to 130 parts by mass per 100 parts by mass of the alkali-soluble resin.

3. 3. The curable resin composition according to claim 1, wherein the amount of the epoxy resin is 30 to 70 parts by mass per 100 parts by mass of the alkali-soluble resin.

4. A dry film used in a method for forming a pattern of a cured product on a circuit board, comprising: the dry film has a resin layer obtained by applying a curable resin composition containing an alkali-soluble resin, a photopolymerization initiator, an inorganic filler, and an epoxy resin to a support; The method for forming a pattern of the cured product includes laminating a resin layer of the dry film on a circuit board, followed by a pattern exposure treatment of the resin layer, a development treatment using an alkaline aqueous solution, and a cleaning treatment using a 0.3 to 3 mass % aqueous citric acid solution or carbonated water prepared by dissolving carbon dioxide gas in pure water and adjusting the pH to 5, in the order of the treatments.

5. 5. The dry film according to claim 4, wherein the inorganic filler is mixed in an amount of 40 to 130 parts by mass with respect to 100 parts by mass of the alkali-soluble resin.

6. 6. The dry film according to claim 4, wherein the amount of the epoxy resin is 30 to 70 parts by mass per 100 parts by mass of the alkali-soluble resin.

7. A cured product obtained by curing the curable resin composition according to any one of claims 1 to 3 or the resin layer of the dry film according to any one of claims 4 to 6.

8. An electronic component comprising the cured product according to claim 7.

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