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

Abstract

To provide a curable resin composition capable of yielding a cured product which offers superior physical properties such as crack resistance and which combines smooth opening pattern wall surfaces with high resolution.SOLUTION: A curable resin composition comprises at least (A) an alkali-soluble resin, (B) a photopolymerization initiator, (C) an inorganic filler, and (D) a thermosetting component, wherein the (C) inorganic filler includes silica having an average particle diameter D50 of 0.3 μm or more and a maximum particle diameter D100 of 2.0 μm or less, and wherein the content of the silica is 35 mass% or more based on the total solid content of the curable resin composition.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a curable resin composition, and more particularly to a curable resin composition that can be suitably used for forming an insulating layer such as a solder resist, a dry film using the curable resin composition, a cured product of the curable resin composition or the dry film, and a printed wiring board using these cured products.

Background Art

[0002] Generally, in a printed wiring board used in electronic devices or the like, in order to prevent solder from adhering to unnecessary portions of the printed wiring board in processes such as solder reflow when mounting electronic components on the printed wiring board, a solder resist layer is formed in a region excluding connection holes on a substrate on which a circuit pattern is formed. The solder resist layer is mainly formed by a so-called photo solder resist in which a curable resin composition is applied to a substrate, dried, pattern-formed by exposure and development, and then the pattern-formed resin is fully cured by heating or light irradiation. In addition, it has also been proposed to form a solder resist layer using a curable dry film without using the above-described liquid curable resin composition.

[0003] In recent years, with the miniaturization and high performance of electronic devices, there has been an increasing need for miniaturization of patterns, reduction of mounting areas, and high-density component mounting in printed wiring boards. Therefore, a curable resin composition for forming a solder resist in a printed wiring board is required to have high resolution. Further, since the printed wiring board is exposed to a high-temperature environment at various stages in the manufacture and use of the printed wiring board, the solder resist is also required to have resistance to thermal stress.

[0004] In order to enhance the resistance to such thermal stress, attempts have been made to control the coefficient of thermal expansion (CTE) of the curable resin composition by adding heat-resistant resins or inorganic materials to the curable resin composition. In particular, in addition to reducing the CTE of the curable resin composition, it is generally practiced to add silica to the curable resin composition in terms of physical properties such as crack resistance, cost, and ease of handling (Patent Document 1).

[0005] However, in the coating film of the curable resin composition highly filled with silica, since the light transmission during exposure is not sufficient, the sensitivity at the via bottom deteriorates, resulting in undercut, or there is a possibility that it may not open sufficiently due to light halation or the like. In response to such problems, it has been proposed to improve the resolution while maintaining physical properties such as crack resistance by using silica having a particle size within a predetermined range (Patent Document 2).

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0007] As proposed in Patent Document 2, by not using silica with a small particle size (less than 0.5 μm), the number of silica particles in the curable resin composition can be reduced, and the problems of undercut and halation can be solved by suppressing light scattering. However, for silica with a small diameter (0.5 μm or more), when a fine opening pattern is formed, the smoothness of the opening wall surface is impaired due to the exposure of silica on the opening wall surface, and there are concerns about problems such as a decrease in reliability.

[0008] Accordingly, an object of the present invention is to provide a curable resin composition capable of obtaining a cured product that is excellent in physical properties such as crack resistance and can achieve both a smooth opening pattern wall surface and good resolution.

Means for Solving the Problems

[0009] As a result of investigations by the present inventors with respect to the above problems, it was found that by using silica having a small diameter and not containing coarse particles at a predetermined content, a cured product excellent in physical properties such as crack resistance and capable of achieving both a smooth opening pattern wall surface and good resolution can be obtained, and a curable resin composition can be realized. The present invention is based on such findings. That is, the gist of the present invention is as follows.

[0010] [1] A curable resin composition comprising at least (A) an alkali-soluble resin, (B) a photopolymerization initiator, (C) an inorganic filler, and (D) a thermosetting component, wherein the (C) inorganic filler contains silica having an average particle diameter D50 of 0.3 μm or more and a maximum particle diameter D100 of 2.0 μm or less, and the content of the silica is 35% by mass or more based on the total solid content of the curable resin composition. [2] The curable resin composition according to [1], wherein the average particle diameter D50 of the silica is 0.3 to 1.0 μm. [3] The curable resin composition according to [1] or [2], wherein the content of the silica is 35 to 90% by mass based on the total solid content of the curable resin composition. [4] The curable resin composition according to any one of [1] to [3], further comprising (E) a photopolymerizable monomer. [5] A dry film comprising a first film and a resin layer obtained by applying and drying the curable resin composition according to any one of [1] to [4] on one surface of the first film. [6] A cured product obtained by curing the curable resin composition according to any one of [1] to [4] or the resin layer of the dry film according to [5]. [7] A printed wiring board having a film made of the cured product described in [6].

Advantages of the Invention

[0011] According to the curable resin composition of the present invention, even when using silica with a small particle diameter and containing no coarse particles at a predetermined content, a cured product can be obtained that is excellent in physical properties such as crack resistance and can achieve both a smooth opening pattern wall surface and good resolution.

Embodiments for Carrying Out the Invention

[0012] [Curable Resin Composition] The curable resin composition according to the present invention contains, as essential components, (A) an alkali-soluble resin, (B) a photopolymerization initiator, (C) an inorganic filler, and (D) a thermosetting component. As the (C) inorganic filler, silica having an average particle diameter D50 of 0.3 μm or more and a maximum particle diameter D100 of 2.0 μm or less is contained at a ratio of 35% by mass or more based on the total solid content of the curable resin composition. As described above, when highly filled with silica from the viewpoint of improving physical properties such as crack resistance, it is known that the resolution decreases and undercut occurs, but this problem can be solved by not using silica with a small particle diameter. However, when forming a fine opening pattern, the smoothness of the opening wall surface may be impaired and the reliability may decrease due to the exposure of silica on the opening wall surface. In the present invention, it is considered that by using silica having an average particle diameter D50 of 0.3 μm or more and a maximum particle diameter D100 of 2.0 μm or less, both a smooth opening pattern wall surface and good resolution can be achieved. Hereinafter, each component constituting the curable resin composition of the present invention will be described.

[0013] <(A) Alkali-Soluble Resin> (A) The alkali-soluble resin contained in the curable resin composition according to the present invention may be any resin that can be made alkali-soluble, and known and commonly used ones are used. The alkali-soluble resin can 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. When the alkali-soluble resin contains a carboxyl group, it can be made alkali-developable. Also, from the viewpoint of curability, in addition to the carboxyl group, it is preferably having an ethylenically unsaturated double bond in the molecule, but only a carboxyl group-containing resin having no ethylenically unsaturated double bond may be used. When the carboxyl group-containing resin has no 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 their derivatives are preferred.

[0014] Specific examples of the carboxyl group-containing resin can include the following compounds (either oligomers or polymers). In this specification, (meth)acrylate is a general term for acrylate, methacrylate, and their mixtures, and the same applies to other similar expressions.

[0015] (1) A carboxyl group-containing resin obtained by copolymerization of an unsaturated carboxylic acid such as (meth)acrylic acid and a compound containing an unsaturated group such as styrene, α-methylstyrene, lower alkyl (meth)acrylate, isobutylene.

[0016] (2) A carboxyl group-containing urethane resin obtained by polyaddition reaction of diisocyanates such as aliphatic diisocyanates, branched aliphatic diisocyanates, alicyclic diisocyanates, and aromatic diisocyanates, 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-based alkylene oxide adduct diols, and compounds having phenolic hydroxyl groups and alcoholic hydroxyl groups.

[0017] (3) A carboxyl group-containing curable urethane resin obtained by partial acid anhydride modification of a reaction product of a diisocyanate with a bifunctional epoxy resin such as bisphenol A type epoxy resin, hydrogenated bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, bixylenol type epoxy resin, and biphenol type epoxy resin and a monocarboxylic acid compound having an ethylenically unsaturated double bond such as (meth)acrylic acid, and by polyaddition reaction of a carboxyl group-containing dialcohol compound and a diol compound.

[0018] (4) A carboxyl group-containing curable urethane resin having terminal (meth)acrylation, obtained by adding a compound having one hydroxyl group and one or more (meth)acryloyl groups in the molecule, such as hydroxyalkyl (meth)acrylate, during the synthesis of the resin of (2) or (3) above.

[0019] (5) A carboxyl group-containing curable urethane resin having terminal (meth)acrylation, obtained 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 of (2) or (3) above.

[0020] (6) A carboxyl group-containing curable resin obtained by reacting a bifunctional or higher polyfunctional (solid) epoxy resin with (meth)acrylic acid and adding a dibasic acid anhydride to the hydroxyl groups present in the side chain.

[0021] (7) A carboxyl group-containing curable resin obtained by reacting (meth)acrylic acid with a polyfunctional epoxy resin obtained by further epoxidizing the hydroxyl groups of a difunctional (solid) epoxy resin with epichlorohydrin and adding a dibasic acid anhydride to the resulting hydroxyl groups.

[0022] (8) A carboxyl group-containing polyester resin obtained by reacting a difunctional oxetane resin with a dicarboxylic acid such as adipic acid, phthalic acid, or hexahydrophthalic acid and adding a dibasic acid anhydride such as phthalic anhydride, tetrahydrophthalic anhydride, or hexahydrophthalic anhydride to the resulting primary hydroxyl groups.

[0023] (9) A carboxyl group-containing curable resin obtained by reacting an epoxy compound having a plurality of 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 reacting a polybasic acid anhydride such as maleic anhydride, tetrahydrophthalic anhydride, trimellitic anhydride, pyromellitic anhydride, or adipic acid with respect to the alcoholic hydroxyl groups of the obtained reaction product.

[0024] (10) A carboxyl group-containing curable resin obtained by reacting a compound having a plurality of phenolic hydroxyl groups in one molecule with an alkylene oxide such as ethylene oxide or propylene oxide, reacting the obtained reaction product with an unsaturated group-containing monocarboxylic acid, and reacting the obtained reaction product with a polybasic acid anhydride.

[0025] (11) A carboxyl group-containing curable resin obtained by reacting a compound having a plurality of phenolic hydroxyl groups in one molecule with a cyclic carbonate compound such as ethylene carbonate or propylene carbonate, reacting the obtained reaction product with an unsaturated group-containing monocarboxylic acid, and reacting the obtained reaction product with a polybasic acid anhydride.

[0026] (12) A carboxyl group-containing curable resin obtained by adding a compound having one epoxy group and one or more (meth)acryloyl groups in one molecule to the resins of (1) to (11) above.

[0027] These carboxyl group-containing resins can be used not limited to those listed above, and may be used alone or in combination of multiple types. Among those described above, carboxyl group-containing resins synthesized using compounds having phenolic hydroxyl groups such as carboxyl group-containing resins (10) and (11) can be preferably used because they are excellent in HAST resistance and PCT resistance.

[0028] The acid value of the carboxyl group-containing resin is preferably 40 to 150 mgKOH / g. By setting the acid value of the carboxyl group-containing resin to 40 mgKOH / g or more, the alkali developability becomes good. Also, by setting the acid value to 150 mgKOH / g or less, it becomes easier to draw a good resist pattern. More preferably, it is 50 to 130 mgKOH / g.

[0029] 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 setting the weight average molecular weight to 2,000 or more, the tack-free performance and resolution can be improved. Also, by setting the weight average molecular weight to 150,000 or less, the developability and storage stability can be improved. More preferably, it is 5,000 to 15,000. The weight average molecular weight can be measured by gel permeation chromatography (GPC).

[0030] The blending amount of the above-mentioned (A) alkali-soluble resin is preferably 10 to 50% by mass in terms of solid content in the curable resin composition. By setting it to 10% by mass or more, the coating film strength can be improved. Also, by setting it to 50% by mass or less, the viscosity becomes appropriate and the printability is improved. More preferably, it is 10 to 30% by mass.

[0031] <(B) Photoinitiator>The photosensitive resin composition according to the present invention contains (B) a photopolymerization initiator in order to photopolymerize the above-mentioned (A) alkali-soluble resin and the (D) photopolymerizable monomer described later. As the photopolymerization initiator, known ones can be used. For example, α-aminoacetophenone-based photopolymerization initiators 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, N,N-dimethylaminoacetophenone; hydroxyacetophenone-based photopolymerization initiators such as 1-hydroxy-cyclohexyl phenyl ketone, 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propan-1-one, 2-hydroxy-1-{4-[4-(2-hydroxy-2-methyl-propionyl)-benzyl]phenyl}-2-methyl-propane-1-one, 2-hydroxy-2-methyl-1-phenylpropan-1-one; acylphosphine oxide-based photopolymerization initiators 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, bis-(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, 2,6-dimethoxybenzoyldiphenylphosphine oxide, 2,6-dichlorobenzoyldiphenylphosphine oxide, 2,4,6-trimethylbenzoylphenylphosphinic acid methyl ester, 2-methylbenzoyldiphenylphosphine oxide, pivaloylphenylphosphinic acid isopropyl ester, 2,4,6-trimethylbenzoyldiphenylphosphine oxide;Benzoin-based photoinitiators such as benzoin, benzyl, benzoin methyl ether, benzoin ethyl ether, benzoin n-propyl ether, benzoin isopropyl ether, benzoin n-butyl ether, etc.; benzoin alkyl ether-based photoinitiators; benzophenone-based photoinitiators such as benzophenone, p-methylbenzophenone, Michler's ketone, methylbenzophenone, 4,4'-dichlorobenzophenone, 4,4'-bisdiethylaminobenzophenone, etc.; acetophenone-based photoinitiators 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-pmorpholino; thioxanthone-based photoinitiators such as thioxanthone, 2-ethylthioxanthone, 2-isopropylthioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2-chlorothioxanthone, 2,4-diisopropylthioxanthone, etc.; anthraquinone-based photoinitiators such as anthraquinone, chloroanthraquinone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-tert-butylanthraquinone, 1-chloroanthraquinone, 2-amylanthraquinone, 2-aminoanthraquinone, etc.; ketal-based photoinitiators such as acetophenone dimethyl ketal, benzyl dimethyl ketal, etc.; benzoic acid ester-based photoinitiators such as ethyl-4-dimethylaminobenzoate, 2-(dimethylamino)ethyl benzoate, ethyl p-dimethylbenzoate, etc.; oxime ester-based photoinitiators such as 1,2-octanedione, 1-[4-(phenylthio)phenyl]-,2-(O-benzoyloxime)], ethanone, 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]-,1-(O-acetoxyoxime), etc.; titanocene-based photoinitiators such as 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-pyr-1-yl)ethyl)phenyl]titanium, etc.;Examples thereof include the following. These photoinitiators may be used alone or in combination of two or more kinds.;

[0032] Examples of commercially available α-aminoacetophenone-based photoinitiators include Omnirad 907, 369, 369E, 379, etc. manufactured by IGM Resins. Examples of commercially available acylphosphine oxide-based photoinitiators include Omnirad 819, etc. manufactured by IGM Resins. Examples of commercially available titanocene-based photoinitiators include JMT-784 manufactured by Yueyang Kimoutain Sci-tech Co., Ltd., GR-FMT manufactured by Hubei Gurun Technology Co., Ltd., etc.

[0033] In addition, a photoinitiator having two oxime ester groups in the molecule can also be preferably used. Specifically, an oxime ester compound having a carbazole structure represented by the following general formula (I) can be mentioned.

Chemical formula

[0034] 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 by an alkyl group having 1 to 17 carbon atoms, an alkoxy group having 1 to 8 carbon atoms, an amino group, an alkylamino group or a dialkylamino group having an alkyl group having 1 to 8 carbon atoms), a naphthyl group (substituted by an alkyl group having 1 to 17 carbon atoms, an alkoxy group having 1 to 8 carbon atoms, an amino group, an alkylamino group or a dialkylamino group having an alkyl group having 1 to 8 carbon atoms), 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 by an alkyl group having 1 to 17 carbon atoms, an alkoxy group having 1 to 8 carbon atoms, an amino group, an alkylamino group or a dialkylamino group having an alkyl group having 1 to 8 carbon atoms), a naphthyl group (substituted by an alkyl group having 1 to 17 carbon atoms, an alkoxy group having 1 to 8 carbon atoms, an amino group, an alkylamino group or a dialkylamino group having an alkyl group having 1 to 8 carbon atoms), an anthryl group, a pyridyl group, a benzofuryl group, a benzothienyl group, 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, 4,2'-styrene-diyl, and n is an integer of 0 or 1.

[0035] In particular, in the above formula, X 1 , Y 1 are each a methyl group or an ethyl group, Z is methyl or phenyl, n is 0, and an oxime ester-based photoinitiator in which Ar is phenylene, naphthylene, thiophene or thienylene is preferred.

[0036] In addition to the above-described photoinitiator, benzoin compounds, acetophenone compounds, anthraquinone compounds, thioxanthone compounds, ketal compounds, benzophenone compounds, tertiary amine compounds, and xanthone compounds can be used as photoinitiators. However, these are preferably used as a photopolymerization initiation aid or a sensitizer in combination with the above-described photopolymerization initiator rather than being used alone as a photopolymerization initiator. Among the above, from the viewpoint of deep curability, thioxanthone compounds and tertiary amine compounds are preferable, and thioxanthone compounds are more preferable. Also, two or more of the above compounds may be used in combination.

[0037] The blending amount of the (B) photopolymerization initiator in the photosensitive resin composition is preferably 1 to 50 parts by mass, more preferably 1 to 20 parts by mass, in terms of solid content, based on 100 parts by mass of the (A) alkali-soluble resin. Thereby, the deep curability can be improved.

[0038] Also, when the photosensitive resin composition contains the above benzoin compound or the like as a photopolymerization initiation aid or the like, the blending amount is preferably 0.01 to 10 parts by mass, more preferably 0.1 to 5 parts by mass, in terms of solid content, based on 100 parts by mass of the (A) alkali-soluble resin. Thereby, the deep curability can be improved.

[0039] <(C) Inorganic filler> The curable resin composition of the present invention contains, as the (C) inorganic filler, silica having an average particle diameter D50 of 0.3 μm or more and a maximum particle diameter D100 of 2.0 μm or less. As described above, for silica with an average particle diameter D50 of less than 0.3 μm, although the smoothness of the opening wall surface when forming a fine opening pattern is excellent, the resolution deteriorates and undercuts are likely to occur. Further, when silica having a maximum particle diameter D100 exceeding 2.0 μm is included, the smoothness of the opening wall surface when forming a fine opening pattern deteriorates. The preferred average particle diameter D50 is 0.3 to 1.0 μm, more preferably 0.3 to 0.80 μm. Also, the preferred maximum particle diameter D100 is 0.3 to 1.0 μm, more preferably 0.7 to 1.5 μm. Note that the "average particle diameter D50" means the value at which the integrated value becomes 50% in the frequency distribution curve obtained by volume-based particle size distribution measurement by the laser diffraction scattering method, and the "maximum particle diameter D100" means the value at which the integrated value becomes 100% in the frequency distribution curve.

[0040] The silica used in the present invention is preferably spherical silica. Spherical silica refers to silica particles whose shape is close to a perfect sphere and whose ratio of the average major axis to the average minor axis is 1 or close to 1. Spherical silica having the above-described predetermined particle diameter can be obtained by appropriately crushing or classifying the raw material silica. The classification may be sieve classification, classification by an air classifier, or a combination of both. Also, when classifying by a sieve, it may be dry classification or wet classification.

[0041] The curable resin composition of the present invention contains silica having the above-described specific particle diameter at a ratio of 35% by mass or more based on the total solid content of the curable resin composition. By highly filling silica in this way, it is possible to improve physical properties such as crack resistance, and to obtain a cured product that can achieve both a smooth opening pattern wall surface and good resolution. The preferred content of silica having the above-described specific particle diameter is 35 to 90% by mass, more preferably 35 to 65% by mass.

[0042] The curable resin composition of the present invention may contain silica other than the silica having the specific particle diameter described above. For example, silica having an average particle diameter D50 of less than 0.3 μm may be included. However, from the viewpoint of the effects of the present invention, when silica having an average particle diameter D50 of less than 0.3 μm is included, its content is preferably less than 25% by mass based on the total solid content of the curable resin composition.

[0043] Further, the silica may be surface-treated in order to enhance its dispersibility in the curable resin composition. By using surface-treated silica, aggregation can be suppressed. The surface treatment method is not particularly limited, and known and commonly used methods may be used. However, it is preferable to treat the surface of the inorganic filler with a surface treatment agent having a curable reactive group, for example, a coupling agent having a curable reactive group as an organic group.

[0044] As the coupling agent, coupling agents such as silane-based, titanate-based, aluminate-based, and zirconium aluminate-based coupling agents can be used. Among them, silane-based coupling agents are preferable. Examples of such silane-based coupling agents 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, 3-mercaptopropyltrimethoxysilane, etc. These can be used alone or in combination. These silane-based coupling agents are preferably adsorbed or immobilized on the surface of silica in advance by adsorption or reaction. Here, the treatment amount of the coupling agent with respect to 100 parts by mass of silica is preferably 0.5 to 10 parts by mass.

[0045] The curable resin composition according to the present invention may contain, as the (C) inorganic filler, other inorganic fillers in addition to the silica described above. As the inorganic filler, known ones can be used, such as talc, mica, aluminum oxide, calcium oxide, magnesium oxide, zinc oxide, calcium carbonate, magnesium carbonate, fly ash, dehydrated sludge, kaolin, clay, calcium hydroxide, aluminum hydroxide, magnesium hydroxide, hydrotalcite, aluminum silicate, magnesium silicate, calcium silicate, wollastonite, potassium titanate, magnesium sulfate, calcium sulfate, magnesium phosphate, sepiolite, zonolite, boron nitride, aluminum borate, silica balloon, glass flake, glass balloon, ironmaking slag, copper, iron, iron oxide, sendust, alnico magnet, magnetic powders such as various ferrites, cement, glass powder, nobelgu silica, diatomaceous earth, antimony trioxide, magnesium oxysulfate, hydrated aluminum, hydrated gypsum, alum and barium sulfate. These inorganic fillers may be used alone or in combination of two or more. Inorganic fillers other than silica may also be surface-treated in the same manner as silica.

[0046] The blending amount of the inorganic filler other than silica, having an average particle diameter D50 of 0.3 μm or more and a maximum particle diameter D100 of 2.0 μm or less in the curable resin composition, can be appropriately adjusted in relation to the blending amount of silica, but is usually adjusted in the range of 0 to 20% by mass.

[0047] <(D) Thermosetting component> In addition to the above-described components, the curable resin composition of the present invention may contain, as an optional component, a (D) thermosetting component. Examples of the thermosetting component include known and commonly used ones 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, a preferred thermosetting component is an epoxy resin.

[0048] Examples of the epoxy resin include bisphenol A type epoxy resin, bisphenol F type epoxy resin, hydrogenated bisphenol A type epoxy resin, brominated bisphenol A type epoxy resin, bisphenol S type epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin, novolac type epoxy resin of bisphenol A, biphenyl type epoxy resin, naphthalene type epoxy resin, dicyclopentadiene type epoxy resin, triphenylmethane type epoxy resin, etc. These may be used alone or in combination of two or more.

[0049] Examples of commercially available epoxy resins include jER 828, 806, 807, YX8000, YX8034, 834 manufactured by Mitsubishi Chemical Corporation, YD-128, YDF-170, ZX-1059, ST-3000 manufactured by Nippon Steel Chemical & Material Co., Ltd., EPICLON 830, 835, 840, 850, N-730A, N-695 manufactured by DIC Corporation, RE-306 manufactured by Nippon Kayaku Co., Ltd., etc.

[0050] The equivalent weight of the epoxy group of the epoxy resin in the curable resin composition is preferably 0.5 to 2.5 in terms of solid content with respect to 1 of the equivalent weight of the carboxyl group of the carboxyl group-containing resin. By setting it to 0.5 equivalent or more, the remaining of the carboxyl group in the cured product can be prevented, and good heat resistance, alkali resistance, electrical insulation, etc. can be obtained. Also, by setting the above blending amount to 2.5 equivalents or less, the remaining of the low molecular weight cyclic (thio) ether group in the dry coating film can be prevented, and the strength of the cured product can be ensured well.

[0051] When the curable resin composition of the present invention contains a thermosetting component, it may contain a thermosetting catalyst for accelerating 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, 1-(2-cyanoethyl)-2-ethyl-4-methylimidazole; amine compounds such as dicyandiamide, benzyldimethylamine, 4-(dimethylamino)-N,N-dimethylbenzylamine, 4-methoxy-N,N-dimethylbenzylamine, 4-methyl-N,N-dimethylbenzylamine; hydrazine compounds such as adipic acid dihydrazide, sebacic acid dihydrazide; phosphorus compounds such as triphenylphosphine and the like. Commercially available products include, for example, 2MZ-A, 2MZ-OK, 2PHZ, 2P4BHZ, 2P4MHZ (all are trade names of imidazole-based compounds) manufactured by Shikoku Kasei Kogyo Co., Ltd., U-CAT 3513N (trade name of a dimethylamine-based compound), DBU, DBN, U-CAT SA 102 (all are bicyclic amidine compounds and their salts) manufactured by San-Apro Ltd.

[0052] It is not limited to the above-mentioned compounds, and any thermosetting catalyst for epoxy resins or oxetane compounds, or any one that promotes the reaction between at least one of epoxy groups and oxetanyl groups and carboxyl groups may be used, and it may be used alone or in combination of two or more. Also, 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, 2,4-diamino-6-methacryloyloxyethyl-S-triazine·isocyanuric acid adduct can be used, and preferably, a compound that also functions as an adhesion promoter is used in combination with the thermosetting catalyst.

[0053] The thermosetting catalyst can be used singly or in combination of two or more. From the viewpoints of the storage stability of the resin composition and the heat resistance of the cured film, the compounding amount of the thermosetting catalyst is preferably 0.01 to 30 parts by mass in terms of solid content based on 100 parts by mass of the alkali-soluble resin, and more preferably 0.1 to 20 parts by mass.

[0054] <(E) Photopolymerizable monomer> The curable resin composition of the present invention may contain (E) a photopolymerizable monomer. The photopolymerizable monomer is a monomer having an ethylenically unsaturated double bond. Examples of such photopolymerizable monomers include commonly known polyester (meth)acrylates, polyether (meth)acrylates, urethane (meth)acrylates, carbonate (meth)acrylates, epoxy (meth)acrylates, and the like. Specifically, alkyl acrylates such as 2-ethylhexyl acrylate and cyclohexyl acrylate; hydroxyalkyl acrylates such as 2-hydroxyethyl acrylate and 2-hydroxypropyl acrylate; mono- or di-acrylates 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; polyacrylates of polyhydric alcohols such as hexanediol, trimethylolpropane, pentaerythritol, ditrimethylolpropane, dipentaerythritol, and tris-hydroxyethyl isocyanurate, or their alkylene oxide adducts or ε-caprolactone adducts; polyacrylates of phenols such as phenoxy acrylate and bisphenol A diacrylate, or their alkylene oxide adducts; acrylates of glycidyl ethers such as glycerin diglycidyl ether, trimethylolpropane triglycidyl ether, and triglycidyl isocyanurate; and not limited to the above, acrylates obtained by directly acrylate-modifying polyols such as polyether polyol, polycarbonate diol, hydroxyl-terminated polybutadiene, and polyester polyol, or urethane acrylate-modifying them via diisocyanate, and melamine acrylate, and at least one of the corresponding methacrylates of the above acrylates can be appropriately selected and used. Such a photopolymerizable monomer can also be used as a reactive diluent.

[0055] The photopolymerizable monomer can be used alone or in combination of two or more. From the viewpoints of photocurability and resolution, the blending amount of the photopolymerizable monomer is preferably 0.5 to 30 parts by mass in terms of solid content based on 100 parts by mass of the alkali-soluble resin.

[0056] <Other Components> In addition to the above-described components, the photosensitive resin composition according to the present invention may contain, if necessary, a colorant, an elastomer, a mercapto compound, a urethanization catalyst, a thixotropic agent, an adhesion promoter, a block copolymer, a chain transfer agent, a polymerization inhibitor, a copper corrosion inhibitor, an antioxidant, a rust preventive agent, a thickener such as organobentonite or montmorillonite, at least one of an antifoaming agent and a leveling agent such as a silicone-based, fluorine-based, or polymer-based agent, and a flame retardant such as a phosphorus compound such as a phosphinate, a phosphate ester derivative, or a phosphazene compound. These can be known substances in the field of electronic materials.

[0057] In the curable resin composition, an organic solvent may be blended from the viewpoints of ease of preparation and coatability when forming the 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 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 kinds.

[0058] The blending amount of the organic solvent in the curable resin composition can be appropriately changed according to the materials constituting the curable resin composition. For example, in terms of solid content conversion, it can be 30 to 300 parts by mass with respect to 100 parts by mass of the alkali-soluble resin.

[0059] In the curable resin composition, components such as an elastomer, a mercapto compound, a urethanization catalyst, a thixotropic agent, an adhesion promoter, a block copolymer, a chain transfer agent, a polymerization inhibitor, a copper corrosion inhibitor, an antioxidant, a rust preventive agent, a thickener such as organic bentonite and montmorillonite, at least one of an antifoaming agent and a leveling agent such as a silicone-based, fluorine-based, and polymer-based antifoaming agent, and a flame retardant such as a phosphorus compound such as a phosphate, a phosphoric acid ester derivative, and a phosphazene compound can be further blended as needed. Known substances in the field of electronic materials can be used for these.

[0060] <Dry film> The curable 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 curable 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 it is laminated and integrally formed by heating or the like so that the resin layer side formed on the dry film is in contact with a base material such as a substrate. The first film may be peeled off from the resin layer in the process after lamination. In particular, in the present invention, it is preferably peeled off from the resin layer in the process after exposure.

[0061] To produce a dry film, the curable resin composition of the present invention is diluted with an organic solvent and adjusted to an appropriate viscosity, and then uniformly coated on the first film with a comma coater, blade coater, lip coater, rod coater, squeeze coater, reverse coater, transfer roll coater, gravure coater, spray coater, etc. to a uniform thickness, and usually dried at a temperature of 50 to 130 ° C for 1 to 30 minutes to obtain a film. There is no particular limitation on the coating film thickness, but generally, it is appropriately selected in the range of 1 to 150 μm, preferably 10 to 60 μm, in terms of the film thickness after drying.

[0062] As the first film, any known film can be used without particular limitation. For example, polyester films such as polyethylene terephthalate and polyethylene naphthalate, polyimide films, polyamideimide films, polypropylene films, and polystyrene films made of thermoplastic resins can be preferably used. Among these, polyester films are preferred from the viewpoints of heat resistance, mechanical strength, handleability, etc. Also, a laminate of these films can be used as the first film.

[0063] In addition, from the viewpoint of improving mechanical strength, the thermoplastic resin film as described above is preferably a film stretched in a uniaxial direction or a biaxial direction.

[0064] The thickness of the first film is not particularly limited, and can be, for example, 10 μm to 150 μm.

[0065] After forming the resin layer of the curable resin composition on the first film, it is preferable to laminate a second film that can be peeled off on the surface of the resin layer for the purpose of preventing dust from adhering to the surface of the resin layer. The second film in the dry film according to the present invention refers to a film that peels off from the resin layer before lamination when it is integrally formed by laminating 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.

[0066] As the second film that can be peeled off from the resin layer, for example, a polyethylene film, a polytetrafluoroethylene film, a polypropylene film, surface-treated paper, etc. can be used, as long as the adhesive force between the resin layer and the second film is smaller than the adhesive force between the resin layer and the first film when the second film is peeled off.

[0067] The thickness of the second film is not particularly limited, and can be, for example, 10 μm to 150 μm.

[0068] <Cured product> The cured product of the present invention is obtained by curing the above-described curable resin composition or the resin layer of the above-described dry film.

[0069] <Printed wiring board> The printed wiring board of the present invention has a cured product obtained from the cured resin composition or the resin layer of the dry film of the present invention. As a method for manufacturing the printed wiring board of the present invention, for example, the curable resin composition of the present invention is adjusted to a viscosity suitable for the coating method using the above organic solvent, and then, on a substrate, by a method such as dip coating, flow coating, roll coating, bar coating, screen printing, curtain coating, etc. After coating, the organic solvent contained in the composition is volatilized and dried (pre-dried) at a temperature of 60 to 100°C to form a tack-free resin layer. In the case of a dry film, after laminating the resin layer onto the substrate so that the resin layer contacts the substrate using a laminator or the like, the first film is peeled off to form a resin layer on the substrate.

[0070] Examples of the above substrate include printed wiring boards and flexible printed wiring boards in which circuits are formed in advance with copper or the like, as well as paper phenol, paper epoxy, glass cloth epoxy, glass polyimide, glass cloth / non-woven cloth epoxy, glass cloth / paper epoxy, synthetic fiber epoxy, high-frequency circuit copper-clad laminates using materials such as fluororesin, polyethylene, polyphenylene ether, polyphenylene oxide cyanate, etc. All grades (such as FR-4) of copper-clad laminates, as well as metal substrates, polyimide films, polyethylene terephthalate films, polyethylene naphthalate (PEN) films, glass substrates, ceramic substrates, wafer plates, etc. can be mentioned.

[0071] In the case of the form of a dry film, it is preferable to perform the lamination onto the substrate under pressure and heating using a vacuum laminator or the like. By using such a vacuum laminator, when using a circuit-formed substrate, even if there are irregularities on the surface of the circuit board, the dry film adheres to the circuit board, so there is no mixing of air bubbles, and the hole-filling property of the recesses on the substrate surface is also improved. The pressure condition is preferably about 0.1 to 2.0 MPa, and the heating condition is preferably 40 to 120°C.

[0072] When the curable resin composition of the present invention contains an organic solvent, after applying the curable resin composition to the substrate surface, it is preferable to perform evaporation drying. Evaporation drying can be carried out using a hot air circulation drying furnace, an IR furnace, a hot plate, a convection oven, etc. (a method of making the hot air in the dryer in countercurrent contact using a heat source of an air heating method by steam and a method of spraying onto the substrate from a nozzle).

[0073] After forming a resin layer on the substrate, it is selectively exposed to active energy rays through a photomask having a predetermined pattern, and the unexposed portion is developed with a dilute alkaline aqueous solution (for example, 0.3 to 3% by 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 developed to form a patterned cured product on the substrate. In addition, in the case of the form of a dry film, as long as the characteristics are not impaired, the first film may be peeled off from the dry film before exposure, and the exposed resin layer may be exposed and developed. Further, by irradiating the cured product with active energy rays and then performing heat curing (for example, 100 to 220 ° C), or irradiating with active energy rays after heat curing, or performing final finishing curing (main curing) only by heat curing, a cured film excellent in various properties such as adhesion and hardness can be formed.

[0074] As the exposure machine used for the above active energy ray irradiation, any device equipped with a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, a metal halide lamp, a mercury short arc lamp, etc. and irradiating ultraviolet rays in the range of 350 to 450 nm may be used. Further, a direct drawing device (for example, a laser direct imaging device that directly draws an image with a laser based on CAD data from a computer) can also be used. The lamp light source or laser light source of the direct drawing machine may have a maximum wavelength in the range of 350 to 450 nm. The exposure amount for image formation varies depending on the film thickness and the like, but generally it can be in the range of 10 to 1000 mJ / cm 2 , preferably 20 to 800 mJ / cm 2 within the range.

[0075] As the above-described development method, dipping method, shower method, spray method, brush method, etc. can be used, and as the developer, an alkaline aqueous solution such as potassium hydroxide, sodium hydroxide, sodium carbonate, potassium carbonate, sodium phosphate, sodium silicate, ammonia, amines, etc. can be used.

[0076] After forming a cured film 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. Also, solder reflow is generally performed under treatment conditions of, for example, 245 to 260 °C for 5 to 10 seconds.

[0077] The curable resin composition or dry film of the present invention is suitably used for manufacturing electronic components such as printed wiring boards, and more preferably, it is used to form a permanent film. At that time, a cured product is formed by the above-described method or the like using the curable resin composition or dry film of the present invention. When the resin layer of the curable resin composition or dry film of the present invention is insulating, it is preferably used to form a solder resist, coverlay, or interlayer insulating layer.

Examples

[0078] Next, the present invention will 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.

[0079] <Preparation of Alkaline-Soluble Resin> Into 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, the temperature was maintained below 40°C, 228 parts of a 25% aqueous sodium hydroxide solution were added, and after the addition, the reaction was carried out at 50°C for 10 hours. After the reaction, it was cooled to 40°C and neutralized to pH 4 with a 37.5% aqueous phosphoric acid solution while maintaining a temperature below 40°C. Then, it was allowed to stand and the aqueous layer was separated. After separation, 300 parts of methyl isobutyl ketone were added and dissolved uniformly, then washed three times with 500 parts of distilled water, and water, solvents, 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. When a part of the obtained methanol solution of the polymethylol compound was dried in a vacuum dryer at room temperature, the solid content was 55.2%. 500 parts of the methanol solution of the obtained polymethylol compound and 440 parts of 2,6-xylenol were charged and dissolved uniformly at 50°C. After uniform dissolution, methanol was removed under reduced pressure at a temperature below 50°C. Then, 8 parts of oxalic acid were added and the reaction was carried out at 100°C for 10 hours. After the reaction, the distillate was removed under reduced pressure at 180°C and 50 mmHg to obtain 550 parts of novolak resin A. Furthermore, into an autoclave equipped with a thermometer, a nitrogen introduction device and an alkylene oxide introduction device, and a stirring device, 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, the system was purged with nitrogen while stirring, then heated up, and 45 parts of ethylene oxide were gradually introduced and reacted at 150°C and 8 kg / cm2. The reaction continued for about 4 hours until the gauge pressure reached 0.0 kg / cm2, and then it was cooled to room temperature. 3.3 parts of a 36% aqueous hydrochloric acid solution were added to and mixed with this reaction solution to neutralize sodium hydroxide. This neutralization reaction product was diluted with toluene, washed three times with water, and the solvent was removed with an evaporator to obtain an ethylene oxide adduct of novolak resin A with a hydroxyl value of 175 g / eq. This was such that an average of 1 mole of ethylene oxide was 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 part of hydroquinone monomethyl ether, and 130 parts of toluene were charged into a reactor equipped with a stirrer, a thermometer, and an air blowing tube. While blowing air and stirring, the temperature was raised to 115°C, and the water generated by the reaction was distilled off as an azeotrope with toluene. After reacting for an additional 4 hours, it was cooled to room temperature. The obtained reaction solution was washed with a 5% aqueous NaCl solution, and after removing toluene by distillation under reduced pressure, 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 part of hydroquinone monomethyl ether, and 0.3 part of triphenylphosphine were charged into a four-necked flask equipped with a stirrer and a reflux condenser. This mixture was heated to 110°C, 45 parts of tetrahydrophthalic anhydride was added, and the reaction was carried out for 4 hours. After cooling, a solution of alkali-soluble resin A with a solid content of 70% and a solid acid value of 65 mgKOH / g was obtained.

[0080] <Preparation of silica> 700 g of commercially available spherical silica (manufactured by Admatechs Co., Ltd., SO-C2) and 300 g of propylene glycol monomethyl ether acetate (PMA) as a solvent were mixed and stirred, and dispersion treatment was carried out using a bead mill until the average particle diameter D50 reached the target particle diameter. After the dispersion treatment, the obtained dispersion was filtered through a 3-μm filter to remove foreign substances and coarse particles, and a silica slurry having the target average particle diameter D50 and maximum particle diameter D100 was obtained. The solid content of the obtained silica slurry was 70% by mass. Next, a silane coupling agent KBM-503 having a methacryl group, manufactured by Shin-Etsu Chemical Co., Ltd., was added to the obtained silica slurry so as to be 4% by mass, and the mixture was dispersed using a bead mill for 10 minutes to obtain a spherical silica slurry (Silicas A to E) surface-treated with methacryl silane. The solid content of each of the obtained spherical silica slurries was 70% by mass. For each of the obtained Silicas A to E, D50 and D100 were measured using NANOTRAC WAVE manufactured by Microtrac Bell Co., Ltd., and the results were as follows. · Silica A (D50 = 0.4 μm, D100 = 1.4 μm · Silica B (D50 = 0.6 μm, D100 = 1.9 μm · Silica C (D50 = 0.3 μm, D100 = 1.0 μm · Silica D (D50 = 0.8 μm, D100 = 3.3 μm · Silica E (D50 = 0.2 μm, D100 = 0.7 μm

[0081] <Preparation of curable resin composition> Each of the components described in Table 1 below was blended and mixed at room temperature using a three-roll mill to obtain each of the curable resin compositions described in the same table. Note that each numerical value in the table indicates parts by mass.

[0082] Note that each of the components *1 to *5 in Table 1 below is as follows. *1: Alkali-soluble resin A obtained above *2: Acylphosphine oxide-based photopolymerization initiator (Omnirad 819, manufactured by IGM Resins) *3: Phenol novolac type epoxy resin (manufactured by DIC Corporation) *4: Dipentaerythritol hexaacrylate (manufactured by Nippon Kayaku Co., Ltd.) *5: Polyacrylate-based surface conditioner (manufactured by BYK-Chemie Japan Co., Ltd.)

[0083] <Smoothness evaluation> Each of the curable resin compositions obtained as described above was applied to a PET film T-100 (thickness 25 μm) manufactured by Mitsubishi Chemical Corporation using an applicator so that the film thickness after drying would be 20 μm, and dried at 80°C for 20 minutes to obtain dry films corresponding to the respective curable resin compositions.

[0084] Next, each dry film was laminated onto a copper-clad substrate chemically polished using Meck Etch Bond CZ-8101 manufactured by Meck & Co., Ltd. using a vacuum laminator CVP-300 manufactured by Nichioh Materials Co., Ltd. at a temperature of 90°C, a vacuum pressure of 3 hPa, a pressing force of 0.4 MPa, and heated for 30 seconds at 90°C, and then flat-pressed at a temperature of 70°C and a pressing force of 0.5 MPa for 1 minute to obtain substrates having layers (dry films) of the respective curable resin compositions that were not exposed. Each of the obtained substrates was exposed using a φ50 μm photomask and an exposure apparatus equipped with a high-pressure mercury lamp (short arc lamp) at the reference exposure amount, and the PET film was peeled off from the dry film. Next, at 30°C and a spray pressure of 2 kg / cm 2 under the conditions of 1 mass% Na 2 CO 3 aqueous solution, development was carried out for 60 seconds to obtain each sample substrate having a cured product with a micropore pattern formed. Each of the obtained sample substrates was irradiated with ultraviolet rays having an integrated exposure amount of 2000 mJ / cm2 using a UV conveyor furnace, and then heated at 150°C for 60 minutes to fully cure the cured product on each sample substrate.

[0085] After subjecting the sample substrates obtained as described above to Pt sputtering treatment, the cross-sectional shape of the micropores on each sample substrate was measured using a scanning electron microscope (×1300 magnification), and the smoothness of the SRO wall surface was evaluated according to the following evaluation criteria. ◎: No coarse particles with a particle size of 1 μm or more are observed on the wall surface of the opening ○: A small amount of coarse particles with a particle size of 1 μm or more are observed on the wall surface of the opening ×: Many coarse particles with a particle size of 1 μm or more are observed on the wall surface of the opening The evaluation results were as shown in Table 1.

[0086] <Resolution evaluation> After performing Pt sputtering treatment on each sample substrate, the cross-sectional shape of the micropores on each sample substrate was measured using a scanning electron microscope (×1300 magnification). The Top diameter and Bottom diameter of the SR opening were measured, and the resolution was evaluated according to the following evaluation criteria based on their size relationship. ◎: Top > Bottom ○: Top = Bottom ×: Top < Bottom The evaluation results were as shown in Table 1.

[0087] <Crack resistance evaluation> A substrate having a cured product with a mounting pattern of Si chips was obtained in the same procedure as the production of the evaluation substrate used in the above-described resolution evaluation, except that the micropore pattern of φ50 μm was replaced with the mounting pattern of Si chips. Next, Au plating treatment and solder bump formation were performed, and Si chips were mounted to obtain each sample substrate for the thermal shock test (TST: Thermal Shock Test). Each of the obtained sample substrates was placed in a thermal cycling machine in which a temperature cycle between -65°C and 150°C was performed in the liquid layer, and TST was performed. During TST, the surface of the cured product on each sample substrate at 500 cycles, 750 cycles, and 1000 cycles was observed, and the crack resistance was evaluated according to the following evaluation criteria. ◎: No abnormality even at 1000 cycles ○: No abnormality at 750 cycles, but cracks were observed at 1000 cycles △: No abnormality at 500 cycles, but cracks were observed at 750 cycles ×: Cracks were observed at 500 cycles The evaluation results were as shown in Table 1.

[0088]

Table 1

[0089] As is clear from Table 1, since the cured products formed from the curable resin compositions of Examples 1 to 3 use a predetermined amount of silica having a D50 of 0.3 μm or more and a D100 of 2.0 μm or less as the inorganic filler, it can be seen that they have good resolution, smoothness of the SRO wall surface, and crack resistance. On the other hand, it can be seen that the cured product formed from the curable resin composition (Comparative Example 1) using silica having a D50 of 0.3 μm or more and a D100 of more than 2.0 μm as the inorganic filler is excellent in resolution and crack resistance but has insufficient smoothness of the SRO wall surface. Also, it can be seen that the cured product formed from the curable resin composition (Comparative Example 2) using silica having a D50 of less than 0.3 μm and a D100 of 2.0 μm or less as the inorganic filler has good smoothness of the SRO wall surface and crack resistance but insufficient resolution. Furthermore, it can be seen that even if the inorganic filler is silica having a D50 of 0.3 μm or more and a D100 of 2.0 μm or less, if its content is less than 35% by mass based on the total solid content of the curable resin composition, the crack resistance is insufficient.

Claims

1. A curable resin composition comprising at least (A) an alkali-soluble resin, (B) a photopolymerization initiator, (C) an inorganic filler, and (D) a thermosetting component, The (C) inorganic filler contains silica having an average particle size D50 of 0.3 μm or more and a maximum particle size D100 of 2.0 μm or less, A curable resin composition, characterized in that the content of the silica is 35 mass% or more based on the total solid content of the curable resin composition.

2. The curable resin composition according to claim 1, wherein the average particle diameter D50 of the silica is 0.3 to 1.0 μm.

3. The curable resin composition according to claim 1, wherein the content of the silica is 35 to 90 mass% based on the total solid content of the curable resin composition.

4. The curable resin composition according to claim 1 , further comprising (E) a photopolymerizable monomer.

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

6. A cured product obtained by curing the curable resin composition according to any one of claims 1 to 4 or the resin layer of the dry film according to claim 5.

7. A printed wiring board provided with a coating comprising the cured product according to claim 6.

Images