Photosensitive resin composition, dry film, cured product, and printed wiring board

Abstract

To provide a photosensitive resin composition that exhibits superior insulation reliability such as HAST resistance and also delivers superior resolution.SOLUTION: A photosensitive resin composition comprises at least (A) an alkali-soluble resin, (B) a photopolymerization initiator, (C) an inorganic filler, and (D) a photopolymerizable monomer, wherein the (D) photopolymerizable monomer contains a compound having at least one (meth)acryloyl group in one molecule, which is formed by transesterification between an unsaturated carboxylic acid ester and an alcohol.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a photosensitive resin composition, and more specifically, to a photosensitive resin composition that can be suitably used for forming an insulating layer such as a solder resist, a dry film using the photosensitive resin composition, a cured product thereof, and a printed wiring board having the cured product. [Background technology]

[0002] In the printed wiring board, from the viewpoint of heat resistance and electrical insulation, photosensitive resin compositions containing modified epoxy acrylate compounds, epoxy resins, etc. as main components and further additive components such as fillers are widely used as interlayer insulating materials and solder resist materials. In recent years, in response to the increase in density of printed wiring boards accompanying the lighter, thinner, shorter, and smaller electronic devices, for example, solder resists are also required to have higher performance, and in particular, permanent coatings such as solder resists used for package substrates are required to have high long-term reliability, specifically high insulation reliability, in addition to physical properties such as heat resistance. In particular, it is expected that the demand for reliability will increase further with the increase in density of package substrates in the future.

[0003] In response to the above demands, it is known that the electrical properties (HAST resistance) of the cured product can be improved by blending an inorganic filler such as silica into a photosensitive resin composition for forming a solder resist. It is also known that a high loading of inorganic filler reduces the resolution and increases the melt viscosity, resulting in poor embeddability, and the resolution and embeddability are improved by using unsaturated carboxylic acid esters such as acrylate monomers as a reactive diluent. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2019-179231 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, an increase in the amount of unsaturated carboxylic acid such as an acrylate monomer has an adverse effect on insulation reliability, and therefore even in a photosensitive resin composition that contains an inorganic filler such as silica and further contains an unsaturated carboxylic acid ester such as an acrylate monomer, there is still room for improvement in order to achieve both excellent insulation reliability and resolution.

[0006] Therefore, an object of the present invention is to provide a photosensitive resin composition having excellent insulation reliability such as HAST resistance and also excellent resolution. Another object of the present invention is to provide a dry film using the photosensitive resin composition, a cured product thereof, and a printed wiring board having the cured product. [Means for solving the problem]

[0007] The unsaturated carboxylic acid esters such as the acrylate monomers described above are generally produced by a dehydration esterification method (direct esterification method) in which an unsaturated carboxylic acid is reacted with an alcohol. In the dehydration esterification method, an acid catalyst such as sulfuric acid is usually used, and it is known that the obtained unsaturated carboxylic acid esters contain a small amount of sulfur. The present inventors have noticed that the small amount of sulfur contained in the unsaturated carboxylic acid esters significantly affects the insulation reliability of the cured product of the photosensitive resin composition, and have found that the insulation reliability is improved by using unsaturated carboxylic acid esters that are substantially free of sulfur. That is, they have found that a photosensitive resin composition that is excellent in insulation reliability such as HAST resistance and also excellent in resolution can be realized by using unsaturated carboxylic acid esters obtained by an ester exchange reaction method between an unsaturated carboxylic acid ester and an alcohol instead of the dehydration esterification method. The present invention is based on such a finding. That is, the gist of the present invention is as follows.

[0008] [1] A photosensitive resin composition comprising at least (A) an alkali-soluble resin, (B) a photopolymerization initiator, (C) an inorganic filler, and (D) a photopolymerizable monomer, A photosensitive resin composition, characterized in that the (D) photopolymerizable monomer contains a compound having at least one (meth)acryloyl group in one molecule, which is an ester exchange product of an unsaturated carboxylic acid ester and an alcohol. [2] The photosensitive resin composition according to [1], wherein the compound having at least one (meth)acryloyl group in one molecule, which is an ester exchange product of the unsaturated carboxylic acid ester and an alcohol, is contained in an amount of 50 mass% or more based on the total amount of the (D) photopolymerizable monomer. [3] The photosensitive resin composition according to [2], wherein the (D) photopolymerizable monomer is contained in an amount of 4 to 10 mass % in terms of solid content based on the total amount of the photosensitive resin composition. [4] The photosensitive resin composition according to any one of [1] to [3], wherein the (C) inorganic filler contains colloidal silica derived from sodium silicate. [5] The photosensitive resin composition according to [4], wherein the colloidal silica is contained in an amount of 40 mass% or more based on the total amount of the (C) inorganic filler. [6] The photosensitive resin composition according to [5], wherein the (C) inorganic filler is contained in an amount of 30 to 50 mass % in terms of solid content based on the total amount of the photosensitive resin composition. [7] The photosensitive resin composition according to any one of [1] to [6], further comprising (E) a thermosetting component. [8] A dry film comprising: a first film; and a resin layer formed by applying the photosensitive resin composition according to any one of [1] to [7] to one surface of the first film and drying the composition. [9] A cured product obtained by curing the resin layer of the photosensitive resin composition according to any one of [1] to [7] or the dry film according to [8].

[10] A printed wiring board having a coating made of the cured product described in [9]. Effect of the Invention

[0009] According to the photosensitive resin composition of the present invention, the photopolymerizable monomer used as the reactive diluent is an ester exchange product of an unsaturated carboxylic acid ester and an alcohol, and contains a compound having at least one (meth)acryloyl group in one molecule, so that a photosensitive resin composition having excellent insulation reliability such as HAST resistance and excellent resolution can be realized. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] [Photosensitive resin composition] The photosensitive resin composition according to the present invention includes, as essential components, (A) an alkali-soluble resin, (B) a photopolymerization initiator, (C) an inorganic filler, and (D) a photopolymerizable monomer, and is characterized in that the photopolymerizable monomer (D) includes a compound having at least one (meth)acryloyl group in one molecule, which is an ester exchange product of an unsaturated carboxylic acid ester and an alcohol. As described above, the conventionally used compound having at least one (meth)acryloyl group in one molecule is obtained by a dehydration esterification method, and therefore inevitably contains sulfur. In the present invention, however, it is considered that the insulation reliability such as HAST resistance is improved by using a compound having at least one (meth)acryloyl group in one molecule that does not substantially contain sulfur. In this specification, the (meth)acryloyl group is a term that collectively refers to an acryloyl group, a methacryloyl group, and both, and the same applies to other similar expressions. Hereinafter, each component constituting the photosensitive resin composition of the present invention will be described.

[0011] <(A) Alkali-soluble resin> The (A) alkali-soluble resin contained in the photosensitive resin composition according to the present invention may be any resin that is alkali-soluble, and known and commonly used resins are used. The alkali-soluble resin may be used alone or in combination of two or more. Examples include water-soluble resins such as carboxyl group-containing resins and phenolic hydroxyl group-containing resins. Among them, carboxyl group-containing resins and phenolic hydroxyl group-containing resins are preferred because of their excellent developability, and carboxyl group-containing resins are more preferred. The alkali-soluble resin can be made alkaline developable by containing a carboxyl group. In addition, from the viewpoint of curability, it is preferable to have an ethylenically unsaturated double bond in the molecule in addition to the carboxyl group, but only a carboxyl group-containing resin that does not have an ethylenically unsaturated double bond may be used. When the carboxyl group-containing resin does not have an ethylenically unsaturated double bond, it is necessary to use a photopolymerizable monomer in combination to make the composition photocurable. As the ethylenically unsaturated double bond, those derived from acrylic acid or methacrylic acid or derivatives thereof are preferred.

[0012] Specific examples of carboxyl group-containing resins include the following compounds (which may be either oligomers or polymers): In this specification, (meth)acrylate is a general term for acrylate, methacrylate, and mixtures thereof, and the same applies to other similar expressions.

[0013] (1) Carboxyl group-containing resins obtained by copolymerizing an unsaturated carboxylic acid such as (meth)acrylic acid with an unsaturated group-containing compound such as styrene, α-methylstyrene, lower alkyl (meth)acrylate, isobutylene, etc.

[0014] (2) Carboxylic acid-containing urethane resins obtained by the polyaddition reaction of diisocyanates such as aliphatic diisocyanates, branched aliphatic diisocyanates, alicyclic diisocyanates, and aromatic diisocyanates with carboxyl-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.

[0015] (3) Carboxylic acid-containing curable urethane resins obtained by the polyaddition reaction of diisocyanates with partially acid anhydride-modified products of reaction products 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 with monocarboxylic acid compounds having ethylenically unsaturated double bonds such as (meth)acrylic acid, carboxyl group-containing dialcohol compounds, and diol compounds.

[0016] (4) A carboxyl group-containing curable urethane resin having a terminal (meth)acrylation formed 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 (3) described above.

[0017] (5) A carboxyl group-containing curable urethane resin having a terminal (meth)acryloyl group added during the synthesis of the resin (2) or (3) by adding a compound having one isocyanate group and one or more (meth)acryloyl groups in the molecule, such as an equimolar reactant of isophorone diisocyanate and pentaerythritol triacrylate.

[0018] (6) A carboxyl group-containing curable 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 group present in the side chain.

[0019] (7) A carboxyl group-containing curable resin obtained by reacting a multifunctional epoxy resin with hydroxyl groups of a bifunctional (solid) epoxy resin further epoxidized with epichlorohydrin, with (meth)acrylic acid, and adding a dibasic acid anhydride to the resulting hydroxyl groups.

[0020] (8) Carboxyl group-containing polyester 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.

[0021] (9) A carboxyl group-containing curable 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 group of the resulting reaction product with a polybasic acid anhydride, such as maleic anhydride, tetrahydrophthalic anhydride, trimellitic anhydride, pyromellitic anhydride, adipic acid, or the like.

[0022] (10) A carboxyl group-containing curable 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 reaction product obtained with an unsaturated group-containing monocarboxylic acid, and reacting the resulting reaction product with a polybasic acid anhydride.

[0023] (11) A carboxyl group-containing curable 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 reaction product obtained with an unsaturated group-containing monocarboxylic acid, and reacting the resulting reaction product with a polybasic acid anhydride.

[0024] (12) A carboxyl group-containing curable resin obtained by further adding a compound having one epoxy group and one or more (meth)acryloyl groups in one molecule to the resins (1) to (11) above.

[0025] The carboxyl group-containing resins are not limited to those listed above, and may be used alone or in combination. Among the above, the carboxyl group-containing resins synthesized using a compound having a phenolic hydroxyl group as a starting material, such as the carboxyl group-containing resins (10) and (11), are preferably used because of their excellent HAST resistance and PCT resistance.

[0026] The acid value of the carboxyl group-containing resin is preferably 40 to 150 mgKOH / g. By making the acid value of the carboxyl group-containing resin 40 mgKOH / g or more, alkaline development becomes good. Also, by making the acid value 150 mgKOH / g or less, it becomes easy to draw a good resist pattern. More preferably, it is 50 to 130 mgKOH / g.

[0027] The weight average molecular weight of the carboxyl group-containing resin varies depending on the resin skeleton, but is generally preferably 2,000 to 150,000. By making the weight average molecular weight 2,000 or more, it is possible to improve tack-free performance and resolution. Furthermore, by making the weight average molecular weight 150,000 or less, it is possible to improve developability and storage stability. It is more preferably 5,000 to 15,000. The weight average molecular weight can be measured by gel permeation chromatography (GPC).

[0028] The amount of the alkali-soluble resin (A) in the photosensitive resin composition is preferably 10 to 50% by mass, calculated as solid content. By making it 10% by mass or more, the coating strength can be improved. Also, by making it 50% by mass or less, the viscosity becomes appropriate and the printability is improved. More preferably, it is 10 to 30% by mass.

[0029] <(B) Photopolymerization initiator>The photosensitive resin composition according to the present invention contains a photopolymerization initiator (B) for photopolymerizing the above-mentioned (A) alkali-soluble resin and the later-described (D) photopolymerizable monomer. As the photopolymerization initiator, a known one can be used, for example, an α-aminoacetophenone-based photopolymerization initiator such as 2-methyl-1-[4-(methylthio)phenyl]-2-morpholino-1-propanone, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butan-1-one, 2-(dimethylamino)-2-[(4-methylphenyl)methyl]-1-[4-(4-morpholinyl)phenyl]-1-butanone, or N,N-dimethylaminoacetophenone; 1-hydroxy-cyclohexylphenylketone; Hydroxyacetophenone photoinitiators such as 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; bis-(2,6-dichlorobenzoyl)phenylphosphine oxide, bis-(2,6-dichlorobenzoyl)-2,5-dimethyl Phenylphosphine 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, bis-(2,4,6-trimethylphenylphosphine oxide, acylphosphine oxide photopolymerization initiators such as methylbenzoyl)-phenylphosphine oxide, 2,6-dimethoxybenzoyldiphenylphosphine oxide, 2,6-dichlorobenzoyldiphenylphosphine oxide, 2,4,6-trimethylbenzoylphenylphosphine acid methyl ester, 2-methylbenzoyldiphenylphosphine oxide, pivaloylphenylphosphine acid isopropyl ester, and 2,4,6-trimethylbenzoyldiphenylphosphine oxide;Benzoin-based photopolymerization initiators such as benzoin, benzil, benzoin methyl ether, benzoin ethyl ether, benzoin n-propyl ether, benzoin isopropyl ether, and benzoin n-butyl ether; benzoin alkyl ether-based photopolymerization initiators; benzophenone-based photopolymerization initiators such as benzophenone, p-methylbenzophenone, Michler's ketone, methylbenzophenone, 4,4'-dichlorobenzophenone, and 4,4'-bisdiethylaminobenzophenone; acetophenone, 2,2-dimethoxy-2-phenylacetophenone acetophenone-based photopolymerization initiators such as 2,2-diethoxy-2-phenylacetophenone, 1,1-dichloroacetophenone, 1-hydroxycyclohexyl phenyl ketone, and 2-methyl-1-[4-(methylthio)phenyl]-2-morpholino-1-propanol; thioxanthone-based photopolymerization initiators such as thioxanthone, 2-ethylthioxanthone, 2-isopropylthioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2-chlorothioxanthone, and 2,4-diisopropylthioxanthone; anthraquinone, chlorothioxanthone, and chlorothioxanthone; Anthraquinone-based photopolymerization initiators such as chloroanthraquinone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-tert-butylanthraquinone, 1-chloroanthraquinone, 2-amylanthraquinone, and 2-aminoanthraquinone; ketal-based photopolymerization initiators such as acetophenone dimethyl ketal and benzyl dimethyl ketal; benzoic acid ester-based photopolymerization initiators such as ethyl-4-dimethylaminobenzoate, 2-(dimethylamino)ethyl benzoate, and p-dimethylbenzoic acid ethyl ester; 1,2-octanedione, 1-[4-(phenyl)anthraquinone ... oxime ester photoinitiators such as ethanone, 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]-, 1-(O-acetyloxime); bis(η5-2,4-cyclopentadien-1-yl)-bis(2,6-difluoro-3-(1H-pyrrol-1-yl)phenyl)titanium, bis(cyclopentadienyl)-bis[2,6-difluoro-3-(2-(1-pyrrol-1-yl)ethyl)phenyl]titanium;These photopolymerization initiators may be used alone or in combination of two or more.

[0030] Commercially available α-aminoacetophenone-based photopolymerization initiators include Omnirad 907, 369, 369E, and 379 manufactured by IGM Resins. Commercially available acylphosphine oxide photopolymerization initiators include Omnirad 819 manufactured by IGM Resins. Commercially available titanocene photopolymerization initiators include JMT-784 manufactured by Yueyang Kimoutain Sci-Tech Co., Ltd. and GR-FMT manufactured by Hubei Kimoutain Sci-Tech Co., Ltd.

[0031] In addition, a photopolymerization initiator having two oxime ester groups in the molecule can also be suitably used, and specific examples thereof include oxime ester compounds having a carbazole structure represented by the following general formula (I). [ka]

[0032] In the above formula, X represents a hydrogen atom, an alkyl group having 1 to 17 carbon atoms, an alkoxy group having 1 to 8 carbon atoms, a phenyl group, a phenyl group (substituted with an alkyl group having 1 to 17 carbon atoms, an alkoxy group having 1 to 8 carbon atoms, an amino group, an alkylamino group having an alkyl group having 1 to 8 carbon atoms, or a dialkylamino group), a naphthyl group (substituted with an alkyl group having 1 to 17 carbon atoms, an alkoxy group having 1 to 8 carbon atoms, an amino group, an alkylamino group having an alkyl group having 1 to 8 carbon atoms, or a dialkylamino group), and Y and Z each represent a hydrogen atom, an alkyl group having 1 to 17 carbon atoms, an alkoxy group having 1 to 8 carbon atoms, a halogen group, a phenyl group, a phenyl group (substituted with an alkyl group having 1 to 17 carbon atoms, an alkoxy group having 1 to 8 carbon atoms, Ar represents an alkylene having 1 to 10 carbon atoms, vinylene, phenylene, biphenylene, pyridylene, naphthylene, thiophene, anthrylene, thienylene, furylene, 2,5-pyrrole-diyl, 4,4'-stilbene-diyl, or 4,2'-styrene-diyl, and n is an integer of 0 or 1.

[0033] In particular, an oxime ester photopolymerization initiator in which, in the above formula, X1 and Y1 are respectively a methyl group or an ethyl group, Z is methyl or phenyl, n is 0, and Ar is phenylene, naphthylene, thiophene, or thienylene is preferred.

[0034] In addition to the above-mentioned photopolymerization initiators, benzoin compounds, acetophenone compounds, anthraquinone compounds, thioxanthone compounds, ketal compounds, benzophenone compounds, tertiary amine compounds, xanthone compounds, etc. can be used as photopolymerization initiators. However, it is preferable to use these compounds as a photopolymerization initiation aid or a sensitizer in combination with the above-mentioned photopolymerization initiators rather than using them alone as a photopolymerization initiator. Among the above, from the viewpoint of deep section curing, thioxanthone compounds and tertiary amine compounds are preferred, and thioxanthone compounds are more preferred. Furthermore, two or more of the above compounds may be used in combination.

[0035] The amount of the photopolymerization initiator (B) in the photosensitive resin composition is preferably 1 to 50 parts by mass, more preferably 1 to 20 parts by mass, based on 100 parts by mass of the alkali-soluble resin (A) in terms of solid content, which can improve the curability in deep areas.

[0036] When the photosensitive resin composition contains the benzoin compound or the like as a photopolymerization initiator, the amount of the benzoin compound or the like is preferably 0.01 to 10 parts by mass, more preferably 0.1 to 5 parts by mass, based on 100 parts by mass of the alkali-soluble resin (A) in terms of solid content, which can improve the curability of the deeper portion.

[0037] The amount of the photopolymerization initiator is preferably 0.5% by mass or more and 5% by mass or less, more preferably 0.5% by mass or more and 3% by mass or less, calculated as solid content based on the total amount of the photosensitive resin composition. When the amount of the photopolymerization initiator is 0.5% by mass or more, the photocurability of the photosensitive resin composition is good, and the coating film properties such as chemical resistance are also good. On the other hand, when the amount is 5% by mass or less, the light absorption at the surface of the resist film (cured coating film) is good, and the deep curability is not likely to decrease.

[0038] A photoinitiator assistant or a sensitizer may be used in combination with the above-mentioned photopolymerization initiator. Examples of the photoinitiator assistant or sensitizer include benzoin compounds, anthraquinone compounds, thioxanthone compounds, ketal compounds, benzophenone compounds, tertiary amine compounds, and xanthone compounds. In particular, it is preferable to use thioxanthone compounds such as 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2-chlorothioxanthone, 2-isopropylthioxanthone, and 4-isopropylthioxanthone. By including a thioxanthone compound, it is possible to improve the deep curing property. Although these compounds may be used as photopolymerization initiators, it is preferable to use them in combination with a photopolymerization initiator. In addition, the photoinitiator assistant or sensitizer may be used alone or in combination of two or more kinds.

[0039] In addition, since these photopolymerization initiators, photoinitiator assistants, and sensitizers absorb specific wavelengths, in some cases the sensitivity is reduced and they may function as ultraviolet absorbers. However, they are not used only for the purpose of improving the sensitivity of the resin composition. If necessary, they can absorb light of a specific wavelength to increase the photoreactivity of the surface, change the line shape and opening of the resist pattern to a vertical, tapered, or reverse tapered shape, and improve the accuracy of the line width and opening diameter.

[0040] <(C) Inorganic filler> The photosensitive resin composition according to the present invention contains an inorganic filler from the viewpoint of improving the reliability of the obtained cured product, such as B-HAST resistance, PCT resistance, heat resistance, high rigidity, thermal dimensional stability, and chemical resistance. The type of inorganic filler is not particularly limited, and conventionally known inorganic fillers can be used. As the inorganic filler, for example, 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, zinc oxide, etc. can be used, and one or more types may be used in combination. Among these, silica is preferable, and spherical silica is more preferable.

[0041] In order to enhance dispersibility in the photosensitive resin composition, the inorganic filler is preferably an inorganic filler with at least a part of its surface treated. In particular, it is preferable that the surface of the inorganic filler is subjected to a surface treatment capable of introducing a curable reactive group. Here, the curable reactive group is not particularly limited as long as it is a group that undergoes a curing reaction with the (A) alkali-soluble resin and the (D) curable compound such as a compound having at least one acryloyl group or methacryloyl group in one molecule described later, and may be a photocurable reactive group or a thermosetting reactive group. Examples of the photocurable reactive group include an acryloyl group, a methacryloyl 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.

[0042] The method of introducing a curable reactive group to the surface of the inorganic filler is not particularly limited, and may be introduced using a known and commonly used method, and the surface of the inorganic filler may be treated with a surface treatment agent having a curable reactive group, for example, a coupling agent having a curable reactive group as an organic group. As the coupling agent, silane-based, titanate-based, aluminate-based, zircoaluminate-based, and other coupling agents may be used. Among these, silane coupling agents are preferred. Examples of the silane coupling agent include vinyltrimethoxysilane, vinyltriethoxysilane, N-(2-aminomethyl)-3-aminopropylmethyldimethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-anilinopropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, and 3-mercaptopropyltrimethoxysilane. These can be used alone or in combination. The amount of the silane coupling agent to be treated with respect to 100 parts by mass of the inorganic filler is preferably 0.5 to 10 parts by mass.

[0043] In the present invention, inorganic colloids may be used as the inorganic filler. Although known and commonly used inorganic colloids can be used, it is preferable that the inorganic colloids are synthesized by various liquid phase methods and have never become dry powder before being mixed into the photosensitive resin composition. Nanoparticles that have become dry powder are difficult to redisperse, causing secondary aggregation and making the decrease in melt viscosity unstable.

[0044] The average particle size of the inorganic colloid is preferably 30 nm or less, more preferably 5 to 25 nm, further preferably 5 to 15 nm, and particularly preferably 5 to 12 nm. When the photosensitive resin composition contains an inorganic colloid having the above average particle size, it is possible to reduce the melt viscosity, prevent light scattering, and improve deep curing properties. The average particle size of the inorganic colloid can be adjusted by the conditions during production. In this specification, the term "average particle size" refers to the volume average particle size (D50 volume%) measured by dynamic light scattering using a laser diffraction measuring device.

[0045] The inorganic colloid is preferably colloidal silica obtained by neutralizing or ion-exchanging sodium silicate (Na2SiO3, also called "water glass") as a raw material. The method for producing colloidal silica is not particularly limited, but as an example, a sodium silicate aqueous solution (also called water glass) is prepared from sodium silicate as a raw material, an acid is added to the sodium silicate aqueous solution to obtain colloidal particles, and the colloidal particles are treated with an ion-exchange resin, and then a base is added to adjust the pH to obtain colloidal silica. The average particle size of colloidal silica can be adjusted by the concentration of the aqueous solution when preparing the colloidal particles. Specifically, colloidal silica having a desired average particle size can be obtained by a known method such as that described in JP-A-06-16414.

[0046] In addition, as the colloidal silica derived from sodium silicate, commercially available products having an average particle size within the above range may be used as they are.Specific examples include SNOWTEX (registered trademark) manufactured by Nissan Chemical Industries, Ltd.: (product numbers) ST-XS, ST-S, ST-30, ST-50-T, ST-UP, ST-PS-S, ST-PS-M, ST-OXS, ST-OS, ST-O, ST-O-40, ST-OUP, ST-PS-SO, ST-PS-MO, ST-NXS, ST-NS, ST-N, ST-N-40, ST-CXS, ST-C, ST-CM, and ST-AK; and organosilica sol manufactured by Nissan Chemical Industries, Ltd.: (product numbers) MA-ST-M, IPA- Examples of colloidal silica derived from sodium silicate include ST, IPA-ST-UP, NPC-ST-30, PGM-ST, PGM-ST-UP, DMAC-ST, NMP-ST, MEK-ST-40, MEK-ST-UP, MIBK-ST, CHO-ST-M, EAC-ST, PMA-ST, TOL-ST, MEK-AC-2140Z, PGM-AC-2140Y, PGM-AC-3140Y, MIBK-AC-2140Z, MEK-EC-2130Y, MEK-EC-2430Z, EP-M2130Y, and EP-M2230Y. One type of colloidal silica derived from sodium silicate may be used alone, or two or more types may be used in combination.

[0047] The colloidal silica derived from sodium silicate may be blended in a slurry state, which facilitates high dispersion and prevents aggregation, making it easy to handle as silica having an average particle size in the above-mentioned specific range.

[0048] The above-mentioned colloidal silica is preferably contained in an amount of 40% by mass or more, and more preferably 50% by mass or more, based on the total amount of the inorganic filler (C). By containing colloidal silica in the inorganic filler, the resolution becomes further improved.

[0049] The amount of the inorganic filler is 30% by mass or more, preferably 30% by mass or more and less than 60% by mass, and more preferably 30% by mass or more and less than 50% by mass, calculated as solid content, based on the total amount of the photosensitive resin composition. When the amount of the inorganic filler is within the above range, the melt viscosity is good and the deep curing property is also good.

[0050] <(D) Photopolymerizable monomer> The photosensitive resin composition according to the present invention contains, as a photopolymerizable monomer (D), a compound having at least one (meth)acryloyl group in one molecule, which is an ester exchange product of an unsaturated carboxylic acid ester and an alcohol. The unsaturated carboxylic acid ester can be used without any particular limitation, and a (meth)acrylate represented by the following formula (1) can be used. [ka]

[0051] In formula (1), R 1 R represents a hydrogen atom or a methyl group. 2 R represents an organic group having 1 to 50 carbon atoms. 2 Preferred specific examples of the alkyl group include alkyl groups having 1 to 8 carbon atoms, such as a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, and a 2-ethylhexyl group; alkoxyalkyl groups, such as a 2-methoxyethyl group, a 2-ethoxyethyl group, and a 2-methoxybutyl group; and dialkylamino groups, such as an N,N-dimethylaminoethyl group, an N,N-diethylaminoethyl group, an N,N-dimethylaminopropyl group, and an N,N-diethylaminopropyl group.

[0052] Among the above-mentioned (meth)acrylates, preferred are alkyl (meth)acrylates having an alkyl group having 1 to 8 carbon atoms, such as methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, i-butyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate, alkoxyalkyl (meth)acrylates such as 2-methoxyethyl acrylate, and N,N-dimethylaminoethyl (meth)acrylate, and more preferred are (meth)acrylates having an alkyl group having 1 to 4 carbon atoms, which show particularly good reactivity with polyhydric alcohols and are easily available, and alkoxyalkyl (meth)acrylates having an alkyl group having 1 to 2 carbon atoms.

[0053] The alcohol can be used without any particular limitation, but a polyhydric alcohol having three or more alcoholic hydroxyl groups can be preferably used. Specific examples of the polyhydric alcohol include hexanediol, trimethylolpropane, pentaerythritol, ditrimethylolpropane, dipentaerythritol, and trishydroxyethyl isocyanurate. Among these, dipentaerythritol is particularly preferred.

[0054] The compound having at least one (meth)acryloyl group in one molecule used in the present invention can be obtained by reacting the above-mentioned unsaturated carboxylic acid ester with an alcohol in the presence of an ester exchange catalyst. The above-mentioned ester exchange reaction product of the unsaturated carboxylic acid ester and the alcohol has a low viscosity and a low impurity content because of a small amount of high molecular weight substances compared to the dehydration esterification reaction, and is characterized by the fact that it does not substantially contain sulfur because an acid catalyst (sulfuric acid) is not used. As a catalyst used in the ester exchange reaction, a combination of one or more compounds selected from azabicyclo compounds, amidine compounds, pyridine compounds, and phosphine compounds and a compound containing zinc can be preferably used. Specifically, a compound having at least one (meth)acryloyl group in one molecule, which is an ester exchange product of an unsaturated carboxylic acid ester and an alcohol, can be obtained by a method described in JP-A-2019-26800 and the like.

[0055] As a compound having at least one (meth)acryloyl group in one molecule, dipentaerythritol hexaacrylate is particularly preferred.

[0056] From the viewpoints of suppressing an increase in viscosity and improving resolution, the compound having at least one (meth)acryloyl group in one molecule is contained in an amount, calculated as solid content, of preferably 4 mass % or more, more preferably 4 to 10 mass %, and even more preferably 4 to 8 mass %, of the total amount of the photosensitive resin composition.

[0057] In addition to the compounds described above as the (D) photopolymerizable monomer, the photosensitive resin composition of the present invention may contain other compounds having a (meth)acryloyl group within the scope of not impairing the effects of the present invention, such as commonly known polyester (meth)acrylates, polyether (meth)acrylates, urethane (meth)acrylates, carbonate (meth)acrylates, epoxy (meth)acrylates, etc. Specific examples include alkyl acrylates such as 2-ethylhexyl acrylate and cyclohexyl acrylate; hydroxyalkyl acrylates such as 2-hydroxyethyl acrylate and 2-hydroxypropyl acrylate; mono- or diacrylates of alkylene oxide derivatives such as ethylene glycol, propylene glycol, diethylene glycol, and dipropylene glycol; acrylamides such as N,N-dimethylacrylamide, N-methylolacrylamide, and N,N-dimethylaminopropylacrylamide; aminoalkyl acrylates such as N,N-dimethylaminoethyl acrylate and N,N-dimethylaminopropyl acrylate; and phenoxy acrylate. and polyhydric acrylates such as phenols, such as bisphenol A diacrylate, or alkylene oxide adducts thereof; acrylates of glycidyl ethers, such as glycerin diglycidyl ether, trimethylolpropane triglycidyl ether, triglycidyl isocyanurate, etc.; and, without being limited to the above, acrylates and melamine acrylates obtained by directly acrilating polyols, such as polyether polyols, polycarbonate diols, hydroxyl-terminated polybutadienes, polyester polyols, etc., or by urethane acrilation via diisocyanates, and the like, and methacrylates corresponding to the above acrylates can be appropriately selected and used.

[0058] <(E) Thermosetting component> The photosensitive resin composition of the present invention may contain, in addition to the above-mentioned components, a thermosetting component (E) as an optional component. Examples of the thermosetting component include known and commonly used components such as isocyanate compounds, blocked isocyanate compounds, amino resins, maleimide compounds, benzoxazine resins, carbodiimide resins, cyclocarbonate compounds, epoxy compounds, oxetane compounds, and episulfide resins. Among these, the preferred thermosetting component is an epoxy resin.

[0059] Examples of epoxy resins include bisphenol A type epoxy resins, bisphenol F type epoxy resins, hydrogenated bisphenol A type epoxy resins, brominated bisphenol A type epoxy resins, bisphenol S type epoxy resins, phenol novolac type epoxy resins, cresol novolac type epoxy resins, bisphenol A novolac type epoxy resins, biphenyl type epoxy resins, naphthalene type epoxy resins, dicyclopentadiene type epoxy resins, triphenylmethane type epoxy resins, and the like. These may be used alone or in combination of two or more.

[0060] Examples of commercially available epoxy resins include jER 828, 806, 807, YX8000, YX8034, and 834 manufactured by Mitsubishi Chemical Corporation; YD-128, YDF-170, ZX-1059, and ST-3000 manufactured by Nippon Steel Chemical & Material Co., Ltd.; EPICLON 830, 835, 840, 850, N-730A, and N-695 manufactured by DIC Corporation; and RE-306 manufactured by Nippon Kayaku Co., Ltd.

[0061] The equivalent weight of the epoxy group of the epoxy resin in the photosensitive resin composition is preferably 0.5 to 2.5 in terms of solid content relative to the equivalent weight of the carboxyl group of the carboxyl group-containing resin (1). By making it 0.5 equivalent weight or more, it is possible to prevent the carboxyl group from remaining in the cured product, and to obtain good heat resistance, alkali resistance, electrical insulation, etc. Also, by making the blending amount 2.5 equivalent weight or less, it is possible to prevent the low molecular weight cyclic (thio)ether group from remaining in the dried coating film, and to ensure good strength of the cured product, etc.

[0062] When the photosensitive resin composition of the present invention contains a thermosetting component, it may contain a thermosetting catalyst for promoting the curing of the thermosetting component. 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. Other commercially available compounds include, for example, 2MZ-A, 2MZ-OK, 2PHZ, 2P4BHZ, and 2P4MHZ (all trade names of imidazole-based compounds) manufactured by Shikoku Chemical Industry Co., Ltd., and U-CAT 3513N (trade name of dimethylamine-based compound), DBU, DBN, and U-CAT SA 102 (all bicyclic amidine compounds and salts thereof) manufactured by San-Apro Co., Ltd.

[0063] The compounds are not limited to the above, and may be used alone or in combination of two or more as long as they are heat curing catalysts for epoxy resins or oxetane compounds, or catalysts that promote the reaction of at least one of epoxy groups and oxetanyl groups with carboxyl groups. In addition, 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 may also be used, and preferably, these compounds that also function as adhesion promoters are used in combination with the heat curing catalyst.

[0064] The thermosetting catalyst may be used alone or in combination of two or more. From the viewpoint of the storage stability of the photosensitive resin composition and the heat resistance of the cured coating, the amount of the thermosetting catalyst is preferably 0.01 to 30 parts by mass, and more preferably 0.1 to 20 parts by mass, calculated as solid content, per 100 parts by mass of the alkali-soluble resin (A).

[0065] <Other ingredients> In addition to the above-mentioned components, the photosensitive resin composition according to the present invention may contain, if necessary, components such as colorants, elastomers, mercapto compounds, urethanization catalysts, thixotropic agents, adhesion promoters, block copolymers, chain transfer agents, polymerization inhibitors, copper inhibitors, antioxidants, rust inhibitors, thickeners such as organic bentonite and montmorillonite, at least one of silicone-based, fluorine-based, and polymer-based defoamers and leveling agents, and flame retardants such as phosphorus compounds such as phosphinates, phosphate ester derivatives, and phosphazene compounds. These may be known in the field of electronic materials.

[0066] The photosensitive resin composition may contain an organic solvent from the viewpoint of ease of preparation and coatability when forming a resin layer. Examples of the organic solvent 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, dipropylene glycol diethyl ether, diethylene glycol monomethyl ether acetate, 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. Known and commonly used organic solvents can be used. These organic solvents can be used alone or in combination of two or more.

[0067] The amount of the organic solvent in the photosensitive resin composition can be appropriately changed depending on the materials constituting the photosensitive resin composition, and can be, for example, 30 to 300 parts by mass, calculated as solid content, per 100 parts by mass of the alkali-soluble resin.

[0068] The photosensitive resin composition may further contain, as necessary, components such as elastomers, mercapto compounds, urethanization catalysts, thixotropic agents, adhesion promoters, block copolymers, chain transfer agents, polymerization inhibitors, copper inhibitors, antioxidants, rust inhibitors, thickeners such as organic bentonite and montmorillonite, at least one of silicone-based, fluorine-based, and polymer-based defoamers and leveling agents, and flame retardants such as phosphorus compounds such as phosphinates, phosphate ester derivatives, and phosphazene compounds. These may be known in the field of electronic materials.

[0069] <Dry film> The photosensitive resin composition of the present invention can also be in the form of a dry film comprising a first film and a resin layer made of the photosensitive resin composition formed on the first film. The first film in the dry film according to the present invention refers to a film that is at least adhered to the resin layer when the film is laminated by heating or the like onto a substrate such as a board so that the resin layer made of the photosensitive resin composition formed on the dry film is in contact with the substrate and integrally molded. The first film may be peeled off from the resin layer in a step after lamination. In particular, in the present invention, it is preferable to peel off from the resin layer in a step after exposure.

[0070] To prepare a dry film, the photosensitive resin composition of the present invention is diluted with an organic solvent to adjust the viscosity to an appropriate level, and then coated onto a first 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, and typically dried for 1 to 30 minutes at a temperature of 50 to 130° C. to obtain a film. There are no particular limitations on the coating film thickness, but it is generally appropriately selected within the range of 1 to 150 μm, preferably 10 to 60 μm, in terms of the film thickness after drying.

[0071] As the first film, any known film can be used without any particular limitation, and for example, a film made of a thermoplastic resin such as a polyester film such as polyethylene terephthalate or polyethylene naphthalate, a polyimide film, a polyamideimide film, a polypropylene film, or a polystyrene film can be suitably used. Among these, a polyester film is preferred from the viewpoints of heat resistance, mechanical strength, handling, etc. A laminate of these films can also be used as the first film.

[0072] From the viewpoint of improving mechanical strength, the above-mentioned thermoplastic resin film is preferably a film stretched in a uniaxial or biaxial direction.

[0073] The thickness of the first film is not particularly limited, but can be, for example, 10 μm to 150 μm.

[0074] After forming a resin layer of the photosensitive resin composition of the present invention on the first film, it is preferable to further laminate a peelable second film on the surface of the resin layer for the purpose of preventing dust from adhering to the surface of the resin layer, etc. The second film in the dry film of the present invention refers to a film that is peeled off from the resin layer before lamination when the dry film is laminated by heating or the like so that the resin layer side of the dry film is in contact with a base material such as a substrate to be integrally molded.

[0075] The second film that can be peeled off from the resin layer may be, for example, a polyethylene film, a polytetrafluoroethylene film, a polypropylene film, surface-treated paper, etc., as long as the adhesive strength between the resin layer and the second film is smaller than the adhesive strength between the resin layer and the first film when the second film is peeled off.

[0076] The thickness of the second film is not particularly limited, but can be, for example, 10 μm to 150 μm.

[0077] <Cured product> The cured product of the present invention is obtained by curing the above-mentioned photosensitive resin composition or the resin layer of the above-mentioned dry film.

[0078] <Printed wiring board> The printed wiring board of the present invention has a cured product obtained from the resin layer of the photosensitive resin composition or dry film of the present invention. As a method for producing the printed wiring board of the present invention, for example, the photosensitive resin composition of the present invention is adjusted to a viscosity suitable for the coating method using the 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, and then the organic solvent contained in the composition is evaporated and dried (temporarily dried) at a temperature of 60 to 100 ° C. to form a tack-free resin layer. In addition, in the case of a dry film, the resin layer is attached to the substrate by a laminator or the like so that the resin layer contacts the substrate, and then the first film is peeled off to form a resin layer on the substrate.

[0079] The above-mentioned substrates include printed wiring boards and flexible printed wiring boards with circuits formed in advance using copper or the like, as well as materials such as paper phenol, paper epoxy, glass cloth epoxy, glass polyimide, glass cloth / non-woven epoxy, glass cloth / paper epoxy, synthetic fiber epoxy, copper-clad laminates for high-frequency circuits using materials such as fluororesin-polyethylene-polyphenylene ether, polyphenylene oxide-cyanate, etc., including copper-clad laminates of all grades (FR-4, etc.), as well as metal substrates, polyimide films, polyethylene terephthalate films, polyethylene naphthalate (PEN) films, glass substrates, ceramic substrates, wafer plates, etc.

[0080] In the case of a dry film form, the lamination onto the substrate is preferably performed under pressure and heat using a vacuum laminator or the like. By using such a vacuum laminator, when a circuit-formed substrate is used, even if the surface of the circuit substrate is uneven, the dry film adheres to the circuit substrate, so that no air bubbles are mixed in, and the filling of the recesses on the substrate surface is improved. The pressure condition is preferably about 0.1 to 2.0 MPa, and the heating condition is preferably 40 to 120°C.

[0081] When the photosensitive resin composition of the present invention contains an organic solvent, it is preferable to apply the photosensitive resin composition to the surface of a substrate and then perform volatilization drying. The volatilization drying can be performed using a hot air circulation drying oven, an IR oven, a hot plate, a convection oven, etc. (a method of countercurrent contact of hot air in a dryer using a heat source of an air heating method using steam, or a method of spraying the hot air from a nozzle onto the substrate).

[0082] After forming a resin layer on a substrate, the resin layer is selectively exposed to active energy rays through a photomask having a predetermined pattern formed thereon, and the unexposed portion is developed with a dilute alkaline aqueous solution (e.g., 0.3 to 3 mass% aqueous sodium carbonate solution) to form a pattern of the cured product. In the case of a dry film, after exposure, the first film is peeled off from the dry film and development is performed to form a patterned cured product on the substrate. In addition, in the case of a dry film form, the first film may be peeled off from the dry film before exposure, and the exposed resin layer may be exposed and developed, as long as the characteristics are not impaired. Furthermore, a cured coating excellent in various properties such as adhesion and hardness can be formed by irradiating the cured product with active energy rays and then heat curing (e.g., 100 to 220°C), or irradiating active energy rays after heat curing, or by heat curing only to perform final finish curing (main curing).

[0083] The exposure machine used for the above-mentioned active energy ray irradiation may be a machine 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 rays in the range of 350 to 450 nm. Furthermore, a direct imaging machine (for example, a laser direct imaging machine 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 machine may have a maximum wavelength in the range of 350 to 450 nm. The exposure dose for forming an image varies depending on the film thickness, etc., but is generally 10 to 1000 mJ / cm. 2 , preferably 20 to 800 mJ / cm 2 The range may be:

[0084] The developing method can be a dipping method, a shower method, a spray method, a brush method, or the like, and the developing solution can be an aqueous alkali solution of potassium hydroxide, sodium hydroxide, sodium carbonate, potassium carbonate, sodium phosphate, sodium silicate, ammonia, amines, or the like.

[0085] After the cured coating is formed on the substrate as described above, components such as electronic elements are mounted on the substrate by solder reflow treatment. The solder reflow treatment can be performed by a conventionally known method. In general, the solder reflow treatment is performed under treatment conditions of, for example, 245 to 260°C for 5 to 10 seconds.

[0086] The photosensitive resin composition or dry film of the present invention is preferably used for manufacturing electronic parts such as printed wiring boards, and more preferably used to form a permanent coating. In this case, the photosensitive resin composition or dry film of the present invention is used to form a cured product by the above-mentioned method or the like. When the resin layer of the photosensitive resin composition or dry film of the present invention is insulating, it is preferably used to form a solder resist, a coverlay, or an interlayer insulating layer. EXAMPLES

[0087] The present invention will now be described in more detail with reference to examples, but the present invention is not limited to these examples. In the following, "parts" and "%" are all based on mass unless otherwise specified.

[0088] <Preparation of alkali-soluble resin> In a flask equipped with a cooling tube and a stirrer, 456 parts of bisphenol A, 228 parts of water, and 649 parts of 37% formalin were charged, and the temperature was kept below 40°C. 228 parts of 25% aqueous sodium hydroxide solution was added, and the reaction was carried out at 50°C for 10 hours after the addition was completed. After the reaction was completed, the mixture was cooled to 40°C, and neutralized to pH 4 with 37.5% aqueous phosphoric acid solution while keeping the temperature below 40°C. The mixture was then left to stand and the aqueous layer was separated. After the separation, 300 parts of methyl isobutyl ketone was added and dissolved uniformly, and the mixture was washed three times with 500 parts of distilled water, and water, solvent, etc. were removed under reduced pressure at a temperature below 50°C. The obtained polymethylol compound was dissolved in 550 parts of methanol to obtain 1230 parts of a methanol solution of the polymethylol compound. A part of the obtained methanol solution of the polymethylol compound was dried at room temperature in a vacuum dryer, and the solid content was 55.2%. 500 parts of the resulting methanol solution of the polymethylol compound and 440 parts of 2,6-xylenol were charged and dissolved uniformly at 50°C. After the mixture was dissolved uniformly, methanol was removed under reduced pressure at a temperature of 50°C or less. Then, 8 parts of oxalic acid was added and reacted at 100°C for 10 hours. After the reaction was completed, the distillate was removed under reduced pressure at 180°C and 50 mmHg to obtain 550 parts of novolak resin A. Further, 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, and the inside of the system was replaced with nitrogen while stirring. Next, the temperature was increased to 150°C and 8 kg / cm 2 45 parts of ethylene oxide was gradually introduced and reacted at a gauge pressure of 0.0 kg / cm. 2 After the reaction was continued for about 4 hours until the reaction solution reached a state where the mixture was cooled to room temperature. 3.3 parts of a 36% aqueous hydrochloric acid solution was added 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 the novolak resin A thus obtained, 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, a thermometer, and an air-inlet tube, and the mixture was stirred while blowing in air, heated to 115°C, and reacted for another 4 hours while distilling off the water generated by the reaction as an azeotropic mixture with toluene, and then cooled to room temperature. The resulting reaction solution was washed with a 5% aqueous NaCl solution, and the toluene was removed by distillation under reduced pressure, and diethylene glycol monoethyl ether acetate was added to obtain an acrylate resin solution with a solid 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, and this mixture was heated to 110°C, 45 parts of tetrahydrophthalic anhydride was added, and the mixture was reacted for 4 hours. After cooling, a solution of alkali-soluble resin A with a solid content of 70% and an acid value of the solid content of 65 mgKOH / g was obtained.

[0089] <Preparation of inorganic filler> 70 g of spherical silica particles (SO-C2 manufactured by Admatechs Co., Ltd., average particle size: 500 nm), 28 g of propylene glycol monomethyl ether acetate as a solvent, and 2 g of a silane coupling agent having a methacryl group (KBM-503 manufactured by Shin-Etsu Chemical Co., Ltd.) were uniformly dispersed to obtain a dispersion of methacrylsilane-treated inorganic filler C1 with a solid content of 70%.

[0090] <Preparation of Photosensitive Resin Composition> The components shown in Table 1 below were blended and mixed at room temperature using a three-roll mill to obtain the photosensitive resin compositions shown in the same table. Each value in the table indicates parts by mass.

[0091] In addition, the components *1 to *10 in Table 1 below are as follows. *1: The above-mentioned alkali-soluble resin A *2: Acylphosphine oxide photopolymerization initiator (2,4,6-trimethylbenzoyldiphenylphosphine oxide) *3: Inorganic filler C1 mentioned above *4: Colloidal silica derived from sodium silicate (Nissan Chemical Co., Ltd., average particle size 12 nm, diluted with propylene glycol monomethyl ether acetate, solid content 42% by mass) *5: Dipentaerythritol hexaacrylate (obtained by the ester exchange method, manufactured by Toa Gosei Co., Ltd.) *6: Dipentaerythritol hexaacrylate (obtained by the dehydration ester method, manufactured by Nippon Kayaku Co., Ltd.) *7: Bisphenol F type epoxy resin (EPICLON N830-A, manufactured by DIC Corporation) *8: Dicyandiamide heat curing catalyst *9: 3-Glycidoxypropyltrimethoxysilane (Shin-Etsu Silicone Co., Ltd.) *10: Polymerization inhibitor (Kinopower QS-30, manufactured by Kawasaki Kasei Chemical Industries, Ltd.)

[0092] <Resolution evaluation> Immediately after preparing each photosensitive resin composition as described above, the composition was applied to the surface of a polyethylene terephthalate film (T-100, manufactured by Mitsubishi Chemical Corporation, thickness 25 μm) as a first film using an applicator so that the film thickness after drying would be 30 μm, and the composition was dried at 80° C. for 10 minutes to prepare a dry film (initial). Next, the dry film was heat-laminated onto a substrate (Cu-plated plate, manufactured by CMK Corporation, 150 mm x 94 mm, thickness 0.8 mm) using a vacuum laminator. After exposure from the dry film side of the substrate through a step tablet (Photec 41 steps) using a DI exposure machine, the first film was peeled off, and a 1 wt% Na2CO3 aqueous solution at 30°C was sprayed at a pressure of 2 kg / cm. 2 The substrate was then exposed to a UV conveyor oven for 60 seconds at an integrated exposure of 2000 mJ / cm. 2 After irradiating with ultraviolet light under the above conditions, the coating was cured by heating at 170° C. for 60 minutes to form a cured film. Of the obtained cured films, the resolution of a pattern with a design value of L / S=100 μm / 100 μm when the step tablet showed a sensitivity of 10 steps was observed using an electron microscope (×1000 magnification), and the undercut (UC) value was calculated using the following formula, and the resolution was evaluated according to the following criteria. ○: UC is less than 10 μm △: UC is 10μm or more and less than 15μ ×: UC is 15 μm or more The evaluation results are shown in Table 1 below.

[0093] <Insulation reliability evaluation> A dry film was prepared in the same manner except that the thickness of the film after drying was 20 μm on a substrate pretreated with CZ8101 manufactured by MEC Co., Ltd., and the dry film was heat laminated using a vacuum laminator onto a substrate on which a comb pattern of L / S=12 / 13 was formed, and exposed using a DI exposure machine. The first film was then peeled off, and a 1 wt% Na2CO3 aqueous solution at 30°C was sprayed at a pressure of 2 kg / cm. 2 The substrate was then exposed to a UV conveyor oven for 60 seconds at an integrated exposure of 2000 mJ / cm. 2 After irradiating with ultraviolet light under the above conditions, the coating was cured by heating at 170° C. for 60 minutes to form a cured film. The fabricated substrate was subjected to HAST under chamber measurement conditions, with a voltage of 13.2 V applied in an environment with a temperature of 130°C and a humidity of 85%. Insulation reliability (BHAST) was evaluated according to the following criteria. ○: 400 hours or more ×: Less than 400 hours The evaluation results are shown in Table 1.

[0094] [Table 1]

[0095] As is clear from Table 1, the photosensitive resin compositions (Examples 1 to 6) using a compound having at least one (meth)acryloyl group in one molecule, which is an ester exchange product of an unsaturated carboxylic acid ester and an alcohol, as a photopolymerizable monomer, have excellent insulation reliability even when the amount of photopolymerizable monomer (acrylate monomer) required to obtain high resolution is added, and it is possible to achieve both resolution and insulation reliability. On the other hand, in the photosensitive resin compositions (Comparative Examples 1 and 2) using an acrylate compound obtained by subjecting an unsaturated carboxylic acid and an alcohol to a dehydration esterification reaction as a photopolymerizable monomer, when the amount of photopolymerizable monomer required to obtain high resolution is added, the insulation reliability becomes insufficient, and it is found that it is difficult to achieve both resolution and insulation reliability.

Claims

1. A photosensitive resin composition comprising at least (A) an alkali-soluble resin, (B) a photopolymerization initiator, (C) an inorganic filler, and (D) a photopolymerizable monomer, The photosensitive resin composition according to claim 1, wherein the photopolymerizable monomer (D) contains a compound having at least one (meth)acryloyl group in one molecule, the compound being an ester exchange product of an unsaturated carboxylic acid ester and an alcohol.

2. 2. The photosensitive resin composition according to claim 1, wherein the compound having at least one (meth)acryloyl group in one molecule, which is an ester exchange product of the unsaturated carboxylic acid ester and an alcohol, is contained in an amount of 50 mass% or more based on the total amount of the photopolymerizable monomer (D).

3. 3. The photosensitive resin composition according to claim 2, wherein the photopolymerizable monomer (D) is contained in an amount of 4 to 10 mass % in terms of solid content based on the total amount of the photosensitive resin composition.

4. The photosensitive resin composition according to claim 1 , wherein the inorganic filler (C) comprises colloidal silica derived from sodium silicate.

5. The photosensitive resin composition according to claim 4 , wherein the colloidal silica is contained in an amount of 40 mass % or more based on the total amount of the inorganic filler (C).

6. The photosensitive resin composition according to claim 5, wherein the inorganic filler (C) is contained in an amount of 30 to 50 mass% in terms of solid content based on the total amount of the photosensitive resin composition.

7. The photosensitive resin composition according to claim 1 , further comprising (E) a thermosetting component.

8. A dry film comprising: a first film; and a resin layer formed by applying the photosensitive resin composition according to claim 1 to one surface of the first film and drying the composition.

9. A cured product obtained by curing the photosensitive resin composition according to claim 1 or the resin layer of the dry film according to claim 8.

10. A printed wiring board provided with a coating comprising the cured product according to claim 9.

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