JP7596487B2 - Curable composition, dry film, cured product and electronic component - Google Patents

Description

The present invention relates to a curable composition, a dry film, a cured product, and an electronic component, and in particular to an alkaline-developable curable composition, a dry film thereof, a cured product thereof, and an electronic component comprising the cured product.

Conventionally, in the solder resist for consumer printed circuit boards and industrial printed wiring boards, from the viewpoint of high precision and high density, liquid development type solder resists have been used, which are developed by irradiating with ultraviolet light to form an image, and then finished cured (main cured) by irradiating with heat and/or light. Among liquid development type solder resists, alkaline development type photo solder resists that use an alkaline aqueous solution as a developer have become mainstream due to environmental considerations.

In general, a silicon-based surface conditioner is added to the solder resist composition that is applied to a substrate to form a photosolder resist on the substrate in order to increase the wettability of the solder resist composition to the substrate and to improve the leveling (flatness) of the coating film.

After the photo solder resist is formed on the board, components are mounted on the board by soldering. However, since molten solder has low wettability to the board, flux is applied to the entire board surface, including the solder resist surface, to improve wettability (to clean the soldering surface and prevent oxidation).

However, the inventors' research has revealed that if a silicon-based surface conditioner is contained in the solder resist formed on a substrate, the flux is repelled from the substrate, resulting in a problem of reduced solderability.

On the other hand, it is well known that silica is added as an inorganic filler to solder resist compositions to increase the rigidity of the solder resist and suppress the cure shrinkage of the solder resist composition.

In the examples of Patent Document 1, an alkali-developable photocurable/thermosetting solder resist composition containing a silicon-based surface conditioner is disclosed as the solder resist composition of the above-mentioned conventional technology, and in Comparative Example 2, an alkali-developable photocurable/thermosetting solder resist composition containing fused spherical silica that has not been subjected to a surface modification treatment as an inorganic powder is disclosed.

JP 2009-194222 A

According to the alkaline development type photocurable/thermosetting solder resist composition containing a silicon-based surface conditioner according to the example of Patent Document 1, the wettability of the solder resist composition to the substrate is improved, but the formed solder resist repels flux, resulting in reduced solderability.

In addition, according to the alkaline development type photocurable/thermosetting solder resist composition of Comparative Example 2 of Patent Document 1, the added silica has not been subjected to a surface modification treatment and is hydrophilic, so if left as is there is a risk of problems with aggregation and precipitation occurring, and it is necessary to eliminate the problems of aggregation and precipitation, for example by modifying the surface to make it hydrophobic. In addition, since no silicon-based surface conditioner is added to the alkaline development type photocurable/thermosetting solder resist composition of Comparative Example 2, the wettability of the solder resist composition to the substrate is not improved.

The present invention was made in consideration of the above problems, and its purpose is to provide a curable composition, dry film, cured product, and electronic component that contain hydrophilic silica and a silicon-based surface conditioner, have good solderability, and eliminate the problem of silica aggregation and precipitation.

The present inventors conducted extensive research to achieve the above object. As a result, they unexpectedly discovered that when a silicone compound, hydrophilic silica, and an organic thixotropic agent were combined, the wettability of the copper-clad substrate and the solder resist composition was maintained while resolving the problems of aggregation and precipitation of hydrophilic silica and the problem of flux repelling caused by the silicone compound, and thus completed the present invention.

That is, the above object of the present invention is to
(A) an alkali-soluble resin;
(B) a photopolymerization initiator;
(C) an epoxy resin;
(D) a silicone compound;
(E) hydrophilic silica; and
(F) an organic thixotropic agent;
It has been found that this can be achieved by a curable composition comprising:

In the curable composition of the present invention, it is further preferable that the median particle size D50 of the hydrophilic silica (E) is 0.2 μm or more and 2.0 μm or less.

It is further preferred that the amount of (F) organic thixotropic agent is 0.01 to 15 parts by mass per 100 parts by mass of (E) hydrophilic silica, and 0.05 parts by mass or more per 2 parts by mass of (D) silicone compound.

In addition, it is preferable to further contain (G) an antioxidant.

The above object of the present invention is also to provide a dry film obtained by applying the curable composition of the present invention onto a carrier film and drying the same.
The objective can also be achieved by a cured product obtained by curing a coating film obtained by applying the curable composition of the present invention onto a substrate and drying the same, or by a coating film obtained by applying the curable composition onto a carrier film and drying the same to obtain a dry film, which is then laminated onto a substrate, and an electronic component comprising the cured product.

According to the present invention, the problem of aggregation and precipitation of hydrophilic silica in the curable composition is resolved, and when the curable composition is applied to a substrate, the silicone compound (D) maintains wettability to the substrate. At the same time, the wettability of the flux to the obtained cured product is improved, so that when the cured product is used as a solder resist, the effect of improving solderability is obtained.

<Curable Composition>
The curable composition of the present invention comprises
(A) an alkali-soluble resin;
(B) a photopolymerization initiator;
(C) an epoxy resin;
(D) a silicone compound;
(E) hydrophilic silica; and
(F) an organic thixotropic agent;
Includes.

[(A) Alkali-soluble resin]
The alkali-soluble resin is a resin that enables the hardenable composition to be dissolved in an alkaline developer, that is, to be developed with an alkali.

As the alkali-soluble resin, it is preferable to use a carboxyl group-containing resin or a phenol resin. In particular, the use of a carboxyl group-containing resin is more preferable in terms of developability.

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

In the present invention, an ethylenically unsaturated group is a substituent having an ethylenically unsaturated bond, and examples of such groups include a vinyl group and a (meth)acryloyl group. From the viewpoint of reactivity, a (meth)acryloyl group is preferable. Here, a (meth)acryloyl group is a general term that refers to an acryloyl group and a methacryloyl group.

Specific examples of carboxyl group-containing resins that do not have ethylenically unsaturated groups include the following compounds (which may be either oligomers or polymers):

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

(2) Carboxylic acid-containing urethane resin obtained by polyaddition reaction of diisocyanate and carboxyl-containing dialcohol compound.

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

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

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

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

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

(7) Carboxyl group-containing photosensitive urethane resins obtained by polyaddition reaction of diisocyanates such as aliphatic diisocyanates, branched aliphatic diisocyanates, alicyclic diisocyanates, and aromatic diisocyanates with diol compounds such as dialcohol compounds containing carboxyl groups, such as dimethylolpropionic acid and dimethylolbutanoic acid, 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.

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

(9) A photosensitive urethane resin containing a carboxyl group, which is terminated with (meth)acrylation by adding a compound having one hydroxyl group and one or more (meth)acryloyl groups in the molecule, such as hydroxyalkyl (meth)acrylate, during the synthesis of the resin (7) or (8) described above.

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

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

(12) A carboxyl group-containing photosensitive resin obtained by reacting a polyfunctional epoxy resin, in which the hydroxyl groups of a bifunctional (solid) epoxy resin are further epoxidized with epichlorohydrin, with (meth)acrylic acid, and then adding a dibasic acid anhydride to the resulting hydroxyl groups.

(13) A carboxyl group-containing polyester photosensitive resin 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.

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

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

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

These photosensitive carboxyl group-containing resins may include those other than those described as (7) to (16), and may be used alone or in combination. Of the carboxyl group-containing resins, resins having aromatic rings are particularly preferred.

The following can be said about the above-mentioned carboxyl group-containing resins, regardless of whether they are photosensitive or non-photosensitive. That is, because they have many carboxyl groups on the side chains of the backbone polymer, they can be developed with a dilute alkaline aqueous solution.

The acid value of the carboxyl group-containing resin is preferably in the range of 40 to 200 mgKOH/g, and more preferably in the range of 45 to 120 mgKOH/g. If the acid value of the carboxyl group-containing resin is within this range, alkaline development becomes easier, dissolution of the exposed area by the developer is suppressed, and the lines do not become thinner than necessary, making it possible to draw a normal pattern that is not dissolved or peeled off by the developer.

The weight-average molecular weight of the carboxyl group-containing resin varies depending on the resin skeleton, but is generally preferably in the range of from 2,000 to 150,000, more preferably from 5,000 to 100,000. If the weight-average molecular weight is within such a range, the tack-free performance is excellent, the moisture resistance of the coating film after exposure is good, and the resolution, developability, and storage stability are excellent.
The amount of the carboxyl group-containing resin in the curable composition (solid content) is suitably in the range of 20% by mass to 80% by mass, preferably 30% by mass to 70% by mass. If the amount of the carboxyl group-containing resin in the curable composition is within this range, the coating strength is not reduced, and thickening or deterioration in workability does not occur.

In addition, in the present invention, as the alkali-soluble resin (A), it is possible to use either a photosensitive carboxyl group-containing resin or a non-photosensitive carboxyl group-containing resin, or to use a mixture of these.

As the phenolic resin, compounds having a phenolic hydroxyl group, for example, compounds having a biphenyl skeleton or a phenylene skeleton or both skeletons, or phenolic hydroxyl group-containing compounds, for example, phenolic resins having various skeletons synthesized using phenol, orthocresol, paracresol, metacresol, 2,3-xylenol, 2,4-xylenol, 2,5-xylenol, 2,6-xylenol, 3,4-xylenol, 3,5-xylenol, catechol, resorcinol, hydroquinone, methylhydroquinone, 2,6-dimethylhydroquinone, trimethylhydroquinone, pyrogallol, phloroglucinol, etc. may be used.

For example, well-known and commonly used phenolic resins such as phenol novolac resin, alkylphenol volac resin, bisphenol A novolac resin, dicyclopentadiene type phenolic resin, Xylok type phenolic resin, terpene modified phenolic resin, polyvinylphenols, bisphenol F, bisphenol S type phenolic resin, poly-p-hydroxystyrene, condensation products of naphthol and aldehydes, and condensation products of dihydroxynaphthalene and aldehydes can be used.

These can be used alone or in combination of two or more.

Examples of commercially available phenolic resins include HF-1M (manufactured by Meiwa Kasei Co., Ltd.), Phenolite TD-2090, Phenolite TD-2131 (manufactured by DIC Corporation), Besumor CZ-256-A (manufactured by DIC Corporation), Shonoru BRG-555, Shonoru BRG-556 (manufactured by Aica Kogyo Co., Ltd.), CGR-951 (manufactured by Maruzen Oil Co., Ltd.), and polyvinylphenols CST70, CST90, S-1P, and S-2P (manufactured by Maruzen Oil Co., Ltd.). These phenolic resins can be used alone or in appropriate combination of two or more types.

[(B) Photopolymerization initiator]
The photopolymerization initiator (B) is added in order to initiate radical polymerization of ethylenically unsaturated groups upon irradiation with energy rays.

(B) Photopolymerization initiators include, for example, benzoin and benzoin alkyl ethers such as benzoin, benzoin methyl ether, benzoin ethyl ether, and benzoin isopropyl ether; acetophenones such as acetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, and 1,1-dichloroacetophenone; 2-methyl-1-[4-(methylthio)phenyl] -2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1, 2-(dimethylamino)-2-[(4-methylphenyl)methyl]-1-[4-(4-morpholinyl)phenyl]-1-butanone and other aminoalkylphenones; 2-methylanthraquinone, 2-ethylanthraquinone, 2-tertiary butylanthraquinone, 1-chloroanthraquinone and other anthraquinones; 2,4-dimethylthioxanthrate thioxanthones such as 2,4-diethylthioxanthone, 2-chlorothioxanthone, and 2,4-diisopropylthioxanthone; ketals such as acetophenone dimethyl ketal and benzyl dimethyl ketal; benzophenones such as 4,4'-bis(diethylamino)benzophenone; (2,6-dimethoxybenzoyl)-2,4,4-pentylphosphine oxide, bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, 2,4,6-trimethylbenzoyl ... Examples of the photopolymerization initiator include phosphine oxides such as ethyl benzoyldiphenylphosphine oxide and ethyl 2,4,6-trimethylbenzoylphenylphosphinate; oxime esters such as 1,2-octanedione, 1-[4-(phenylthio)-, 2-(O-benzoyloxime)], ethanone, 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]-, and 1-(O-acetyloxime); various peroxides, titanocene initiators, and the like. These may be used in combination with photosensitizers such as N,N-dimethylaminobenzoic acid ethyl ester, N,N-dimethylaminobenzoic acid isoamyl ester, pentyl-4-dimethylaminobenzoate, triethylamine, triethanolamine, and other tertiary amines. These photopolymerization initiators may be used alone or in combination of two or more.

The amount of (B) photopolymerization initiator blended in the curable composition of the present invention is in the range of 0.01 parts by mass to 30 parts by mass, preferably 0.5 parts by mass to 20 parts by mass, per 100 parts by mass (solid content) of (A) alkali-soluble resin.

[(C) Epoxy resin]
The epoxy resin (C) is a compound added for thermally curing the curable composition of the present invention.

(C) Epoxy resin may be a known, commonly used multifunctional epoxy resin having at least two epoxy groups in one molecule. (C) Epoxy resin may be, for example, jER828, jER834, jER1001, jER1004 manufactured by Mitsubishi Chemical Corporation, EPICLON840, EPICLON850, EPICLON850-S, EPICLON1050, EPICLON2055 manufactured by DIC Corporation, Epotohto YD-011, YD-013, YD-127, YD-128 manufactured by Tohto Kasei Co., Ltd., D.E.R.317, D.E.R.331, D.E.R.661, D.E.R.201, D.E.R.302, D.E.R.303, D.E.R.304, D.E.R.305, D.E.R.306, D.E.R.307, D.E.R.309, D.E.R.409, D.E.R.408, D.E.R.509, D.E.R.509, D.E.R.601, D.E.R.602, D.E.R.701, D.E.R.801, D.E.R.901, D.E.R.102, D.E.R.103, D.E.R.104, D.E.R.105, D.E.R.106, D.E.R.107, D.E.R.108, D.E.R.109 ... 664, bisphenol A type epoxy resins such as Sumi-Epoxy ESA-011, ESA-014, ELA-115, ELA-128 (all trade names) manufactured by Sumitomo Chemical Co., Ltd.; jER YL903 manufactured by Mitsubishi Chemical Co., Ltd., EPICLON152, EPICLON165 manufactured by DIC Corporation, Epotohto YDB-400, YDB-500 manufactured by Tohto Kasei Co., Ltd., D.E.R.542 manufactured by Dow Chemical Co., Ltd., Sumi-Epoxy ESB-400, ESB-700 (all trade names) and other brominated epoxy resins; jER152, jER154 manufactured by Mitsubishi Chemical Co., Ltd., D.E.N.431, D.E.N.432, D.E.N.433, D.E.N.434, D.E.N.435, D.E.N.436, D.E.N.437, D.E.N.438, D.E.N.530, D.E.N.531, D.E.N.532, D.E.N.533, D.E.N.534, D.E.N.535, D.E.N.536, D.E.N.537, D.E.N.538, D.E.N.539, D.E.N.631, D.E.N.632, D.E.N.633, D.E.N.634, D.E.N.635, D.E.N.636, D.E.N.637, D.E.N.638, D.E.N.639, D.E.N.731, D.E.N.731, D.E.N.831, D.E.N 438, EPICLON N-730, EPICLON N-770, EPICLON N-865 manufactured by DIC, Epotohto YDCN-701, YDCN-704 manufactured by Tohto Kasei, EPPN-201, EOCN-1025, EOCN-1020, EOCN-104S, RE-306, NC-3000 manufactured by Nippon Kayaku, Sumi-Epoxy ESCN-195X, ESCN-220 manufactured by Sumitomo Chemical, YDCN-700-2, YDCN-700-3, YDCN-700-5, YDCN-700-7, YDCN-700-10, YDCN-704 YDCN-704A manufactured by Nippon Steel Chemical, EPICLON manufactured by DIC N-680, EPICLON N-690, EPICLON Novolac type epoxy resins such as N-695 (all trade names); bisphenol F type epoxy resins such as EPICLON 830 manufactured by DIC Corporation, jER807 manufactured by Mitsubishi Chemical Corporation, and Epotohto YDF-170, YDF-175, and YDF-2004 manufactured by Tohto Kasei Co., Ltd. (all trade names); hydrogenated bisphenol A type epoxy resins such as Epotohto ST-2004, ST-2007, and ST-3000 (trade names) manufactured by Tohto Kasei Co., Ltd. and YX8034 manufactured by Mitsubishi Chemical Corporation; glycidylamine type epoxy resins such as jER604 manufactured by Mitsubishi Chemical Corporation, Epotohto YH-434 manufactured by Tohto Kasei Co., Ltd., and Sumi-Epoxy ELM-120 manufactured by Sumitomo Chemical Co., Ltd. (all trade names); hydantoin type epoxy resins; alicyclic epoxy resins such as Celloxide 2021 (trade name) manufactured by Mitsubishi Chemical Corporation; trihydroxyphenylmethane type epoxy resins such as YL-933 manufactured by Mitsubishi Chemical Corporation and EPPN-501 and EPPN-502 (trade name) manufactured by Nippon Kayaku Co., Ltd.; bixylenol type or biphenol type epoxy resins or mixtures thereof such as YL-6056, YX-4000, and YL-6121 (trade name) manufactured by Mitsubishi Chemical Corporation; bisphenol S type epoxy resins such as EBPS-200 manufactured by Nippon Kayaku Co., Ltd., EPX-30 manufactured by ADEKA Corporation, and EXA-1514 (trade name) manufactured by DIC Corporation; bisphenol A novolac type epoxy resins such as jER157S (trade name) manufactured by Mitsubishi Chemical Corporation; jER manufactured by Mitsubishi Chemical Corporation Tetraphenylolethane type epoxy resins such as YL-931 (all trade names); diglycidyl phthalate resins such as BLEMMER DGT manufactured by NOF Corporation; heterocyclic epoxy resins such as TEPIC manufactured by Nissan Chemical Industries, Ltd. (all trade names); tetraglycidyl xylenoylethane resins such as ZX-1063 manufactured by Tohto Kasei Co., Ltd.; naphthalene group-containing epoxy resins such as ESN-190, ESN-360 manufactured by Nippon Steel Chemical Co., Ltd., HP-4032, EXA-4750, EXA-4700 manufactured by DIC Corporation, etc. epoxy resins; epoxy resins having a dicyclopentadiene skeleton, such as HP-7200 and HP-7200H manufactured by DIC Corporation; glycidyl methacrylate copolymer epoxy resins, such as CP-50S and CP-50M manufactured by NOF Corporation; further, copolymer epoxy resins of cyclohexylmaleimide and glycidyl methacrylate; CTBN-modified epoxy resins (e.g., YR-102 and YR-450 manufactured by Tohto Kasei Co., Ltd.), but are not limited to these.

When (C) epoxy resin is blended, it is blended in an amount of 0.8 to 2.0 epoxy equivalents relative to the carboxylic acid equivalent of (A) alkali-soluble resin. Here, the carboxylic acid equivalent represents the weight of (A) alkali-soluble resin required to obtain 1 mol of carboxyl groups, and is expressed in g/mol. The epoxy equivalent represents the weight of (C) epoxy resin required to obtain 1 mol of epoxy groups, and is expressed in g/mol. The mass of (C) epoxy resin is 0.8 to 2.0 epoxy equivalents relative to the carboxylic acid equivalent of (A) alkali-soluble resin. When the epoxy equivalent is within this range, a cured product with excellent heat resistance, electrical properties, and crack resistance can be obtained.

[(D) Silicone compound]
The silicone compound (D) is blended to improve the wettability of the curable composition of the present invention to a copper-clad substrate (base material), suppress repellency, and improve leveling properties.

The (D) silicone compound is polydimethylsiloxane or a derivative having a polydimethylsiloxane basic structure, and examples thereof include polydimethylsiloxane, polyether-modified polydimethylsiloxane, polyester-modified polydimethylsiloxane, polyester-modified polymethylalkylsiloxane, polyether-modified polymethylalkylsiloxane, aralkyl-modified polymethylalkylsiloxane, polyether-modified siloxane, and polyester-modified hydroxyl-containing polydimethylsiloxane.

(D) Commercially available silicone compounds include BYK (registered trademark)-300, BYK (registered trademark)-302, BYK (registered trademark)-306, BYK (registered trademark)-307, BYK (registered trademark)-310, BYK (registered trademark)-315N, BYK (registered trademark)-320, BYK (registered trademark)-322, BYK (registered trademark)-323, BYK (registered trademark)-325, BYK (registered trademark)-330, BYK (registered trademark) -331, BYK (registered trademark)-333, BYK (registered trademark)-342, BYK (registered trademark)-345, BYK (registered trademark)-346, BYK (registered trademark)-347, BYK (registered trademark)-348, BYK (registered trademark)-349, BYK (registered trademark)-370, BYK (registered trademark)-377, BYK (registered trademark)-378, BYK (registered trademark)-3455) (all manufactured by BYK Japan KK).

The silicone compound (D) is blended in the curable composition of the present invention in an amount of 0.1 to 10 parts by mass, preferably 1 to 5 parts by mass, per 100 parts by mass (solids) of the alkali-soluble resin (A). By blending the silicone compound (D) in an amount of 0.1 to 10 parts by mass, the wettability of the curable composition to the copper-clad substrate (base material) is ensured, the leveling properties are good, and the wettability of the flux to the cured product is also good.

[(E) Hydrophilic Silica]
(E) Hydrophilic silica is added to suppress cure shrinkage of the curable composition of the present invention and to increase the rigidity of the obtained cured product.

In the present invention, (E) hydrophilic silica refers to untreated silica that has not been subjected to a surface treatment to add hydrophobic organic groups to its hydrophilic surface, and examples of such silica include fused silica, spherical silica, amorphous silica, and crystalline silica.

Note that the surface treatment to add hydrophobic organic groups refers to treating the surface of (untreated) hydrophilic silica with a coupling agent having a hydrophobic organic group such as an ethylenically unsaturated group (photocurable reactive group) or an alkyl group, and silica that has been subjected to such surface treatment is not included in the above-mentioned (E) hydrophilic silica.

Commercially available products include FB-15D, FB-105, FB-105X, FB-5SDX, SFP-20M, SFP-130MC (all manufactured by Denki Kagaku Kogyo Co., Ltd.), Excelilica (registered trademark) (manufactured by Tokuyama Corporation), and SR-NP (manufactured by M-Tech Chemical Co., Ltd.).

(E) Hydrophilic silica has a median diameter (D50) of 30 μm or less when used to form a cured film on a printed wiring board, and 5 μm or less when used to form a cured film on an IC package substrate. From the viewpoint of dispersibility in the curable composition, a median diameter (D50) of 0.2 μm or more and 2 μm or less is preferable. The method for measuring the median diameter (D50) is as follows.

<Method of measuring median diameter (D50)>
30 ml of ethanol and 1 g of silica powder were placed in a 100 ml beaker and stirred for 3 minutes in a tabletop ultrasonic cleaner. The volume-based median diameter (D50) was then measured in ethanol solvent using a laser diffraction/scattering particle size distribution analyzer (Microtrac MT-3300, manufactured by Microtrac-Bell).

In addition, (E) hydrophilic silica is blended in the curable composition of the present invention in a range of 10 parts by mass to 200 parts by mass, preferably 20 parts by mass to 180 parts by mass, per 100 parts by mass (solid content) of (A) alkali-soluble resin. By blending (E) hydrophilic silica in a range of 10 parts by mass to 200 parts by mass, it is possible to obtain the effects of suppressing cure shrinkage and enhancing the rigidity of the cured product, while also achieving good dispersibility.

[(F) Organic thixotropic agent]
The organic thixotropic agent (F) is added to suppress aggregation and precipitation of the hydrophilic silica (E) in the curable composition of the present invention, and, as has become clear for the first time in the present invention, to improve the wettability of the flux to the cured product of the curable composition of the present invention.

The organic thixotropic agents (F) that can be used in the curable composition of the present invention include fatty acid amides (amide wax type) synthesized from vegetable oil fatty acids and amines; surfactants such as fatty acid esters, polyethers, sulfated oils, and higher alcohol sulfates; polycarboxylic acid esters; polycarboxylic acid amides; and urea-modified compounds, but do not include hydrogenated castor oil type, known as castor oil wax, or oxidized polyethylene type, which is a wax obtained by oxidizing polyethylene and introducing polar groups.

(F) Commercially available organic thixotropic agents include BYK (registered trademark)-R606, BYK (registered trademark)-405, BYK (registered trademark)-R605, BYK (registered trademark)-R607, BYK (registered trademark)-410, BYK (registered trademark)-411, BYK (registered trademark)-415, BYK (registered trademark)-430, BYK (registered trademark)-431, BYK (registered trademark)-7410ET, BYK (registered trademark)-7411ES (hereinafter referred to as (manufactured by BYK Japan), TALEN 1450, TALEN 2000, TALEN 2200A, TALEN 7200-20, TALEN 8200-20, TALEN 8300-20, TALEN 8700-20, TALEN BA-600, FLUONON SH-290, FLUONON SH-295S, FLUONON SH-350, FLUONON HR-2, and FLUONON HR-4AF (all manufactured by Kyoeisha Chemical Co., Ltd.).

In the curable composition of the present invention, the amount of the (F) organic thixotropic agent is 0.01 parts by mass or more and 15 parts by mass or less, and preferably 0.05 parts by mass or more and 10 parts by mass or less, per 100 parts by mass (solid content) of the (E) hydrophilic silica.

The amount of the (F) organic thixotropic agent in the curable composition of the present invention is 0.05 parts by mass or more, and preferably 0.1 parts by mass or more, per 2 parts by mass of the (D) silicone compound.

By being within the above range, (E) the hydrophilic silica is well dispersed, and the flux also has good wettability with respect to the cured product of the curable composition.

[(G) Antioxidant]
The curable composition of the present invention preferably contains an antioxidant (G) which inhibits oxidation of copper in a copper-clad substrate (substrate) and thereby improves adhesion between the substrate and the curable composition.

(G) Examples of antioxidants include hindered phenol compounds such as 3-(N-salicyloyl)amino-1,2,4-triazole, sulfur-based antioxidants such as zinc salts of 2-mercaptobenzimidazole, phosphorus-based antioxidants such as triphenyl phosphite, aromatic amine-based antioxidants such as di-tert-butyldiphenylamine, and heterocyclic dry compounds containing nitrogen as a heteroatom (excluding sulfur-based antioxidants) such as melamine, benzotriazole, and tolyltriazole. Of these, melamine is preferred.

The amount of (G) antioxidant blended is 0.1 parts by mass or more and 5 parts by mass or less, and preferably 0.5 parts by mass or more and 2 parts by mass or less, per 100 parts by mass (solid content) of (A) alkali-soluble resin in the curable composition of the present invention.

[Other ingredients]
Further, it is preferable to add a photopolymerizable polyfunctional monomer to the curable composition of the present invention. The photopolymerizable polyfunctional monomer is a compound having two or more ethylenically unsaturated groups in one molecule, and is used to assist the photocuring of the alkali-soluble resin (A) by irradiation with active energy rays (when the alkali-soluble resin (A) contains an ethylenically unsaturated group) and to photocure the curable composition.

Examples of compounds used as photopolymerizable polyfunctional monomers include commonly known polyester (meth)acrylates, polyether (meth)acrylates, urethane (meth)acrylates, carbonate (meth)acrylates, and epoxy (meth)acrylates. Specific examples include polyhydric alcohols such as hexanediol, trimethylolpropane, pentaerythritol, dipentaerythritol, and tris-hydroxyethyl isocyanurate, or polyhydric acrylates such as ethylene oxide adducts, propylene oxide adducts, or ε-caprolactone adducts of these polyhydric alcohols; polyhydric acrylates such as phenoxy acrylate, bisphenol A diacrylate, and ethylene oxide adducts or propylene oxide adducts of these phenols; glycerin diglycidyl ether, glyceryl ether, and the like. Polyhydric acrylates of glycidyl ethers such as triglycidyl ether, trimethylolpropane triglycidyl ether, and triglycidyl isocyanurate; but are not limited to the above, examples include acrylates and melamine acrylates obtained by directly acrilating polyols such as polyether polyols, polycarbonate diols, hydroxyl-terminated polybutadienes, and polyester polyols, or by urethane acrilation via diisocyanates, and at least one of the methacrylates corresponding to the above acrylates.

The photopolymerizable polyfunctional monomer is blended in the curable composition of the present invention in a range of 3 parts by mass to 30 parts by mass, preferably 10 parts by mass to 20 parts by mass, per 100 parts by mass (solid content) of the alkali-soluble resin (A).

The curable composition of the present invention preferably further contains a curing catalyst such as dicyandiamide, boron trifluoride-amine catalyst, or organic acid hydrazide. The curing catalyst is added to the curable composition of the present invention in an amount of 5 parts by mass or less, preferably 0.1 parts by mass or more and 2 parts by mass or less, per 100 parts by mass (solid content) of the alkali-soluble resin (A).

Furthermore, color pigments, dyes, etc. may be added to the curable composition of the present invention for the purpose of coloring. As the color pigments, dyes, etc., known and commonly used ones represented by the color index can be used. For example, Pigment Blue 15, 15:1, 15:2, 15:3, 15:4, 15:6, 16, 60, Solvent Blue 35, 63, 68, 70, 83, 87, 94, 97, 122, 136, 67, 70, Pigment Green 7, 36, 3, 5, 20, 28, Solvent Yellow 163, Pigment Yellow 24, 108, 193, 147, 199, 202, 110, 109, 139 179 185 93, 94, 95, 128, 155, 166, 180, 120, 151, 154, 156, 175, 181, 1, 2, 3, 4, 5, 6, 9, 10, 12, 61, 62, 62:1, 65, 73, 74, 75, 97, 100 , 104, 105, 111, 116, 167, 168, 169, 182, 183, 12, 13, 14, 16, 17, 55, 63, 81, 83, 87, 126, 127, 152, 170, 172, 174, 176, 188, 198, Pigment Orange 1, 5, 13, 14, 16, 17, 24, 34, 36, 38, 40, 43, 46, 49, 51, 61, 63, 64, 71, 73, Pigment Red 1, 2, 3, 4, 5, 6, 8, 9, 12, 14, 15, 16, 17, 21, 22, 23, 31, 32, 112, 114, 146, 147, 151, 170, 184, 187, 188, 193, 2 10, 245, 253, 258, 266, 267, 268, 269, 37, 38, 41, 48:1, 48:2, 48:3, 48:4, 49:1, 49:2, 50:1, 52:1, 52:2, 53 :1, 53:2, 57:1, 58:4, 63:1, 63:2, 64:1, 68, 171, 175, 176, 185, 208, 123, 149, 166, 178, 179, 190, 194, 224 , 254, 255, 264, 270, 272, 220, 144, 166, 214, 220, 221, 242, 168, 177, 216, 122, 202, 206, 207, 209, Solvent Examples of the pigments and dyes include Red 135, 179, 149, 150, 52, and 207, Pigment Violet 19, 23, 29, 32, 36, 38, and 42, Solvent Violet 13 and 36, Pigment Brown 23 and 25, and Pigment Black 1 and 7. These color pigments and dyes can be added in an amount of 0.01 to 5 parts by mass, preferably 0.1 to 3 parts by mass, per 100 parts by mass of the curable composition.

Furthermore, if necessary, known and commonly used additives such as known and commonly used polymerization inhibitors such as hydroquinone, hydroquinone monomethyl ether, t-butylcatechol, pyrogallol, and phenothiazine, photopolymerization sensitizers, light stabilizers, dispersants, flame retardants, and flame retardant assistants can be added.

The curable composition of the present invention may also contain an organic solvent used to adjust the viscosity. Examples of organic solvents that can be used include ketones such as methyl ethyl ketone and cyclohexanone; aromatic hydrocarbons such as toluene, xylene, and tetramethylbenzene; glycol ethers such as cellosolve, methyl cellosolve, butyl cellosolve, carbitol, methyl carbitol, butyl carbitol, propylene glycol monomethyl ether, dipropylene glycol monomethyl ether (DPM), dipropylene glycol diethyl ether, and tripropylene glycol monomethyl ether; esters such as ethyl acetate, butyl acetate, butyl lactate, cellosolve acetate, butyl cellosolve acetate, carbitol acetate, butyl carbitol acetate, propylene glycol monomethyl ether acetate, dipropylene glycol monomethyl ether acetate, and propylene carbonate; aliphatic hydrocarbons such as octane and decane; and petroleum-based solvents such as petroleum ether, petroleum naphtha, and solvent naphtha. These organic solvents can be used alone or in combination of two or more.

<Dry film and cured product of the curable composition of the present invention>
The curable composition of the present invention can be in the form of a dry film obtained by applying it to a carrier film (support) and drying it. When forming a dry film, the curable composition of the present invention is diluted with the above-mentioned organic solvent to adjust the viscosity to an appropriate level, and applied to a carrier film in a uniform thickness using a comma coater, blade coater, lip coater, rod coater, squeeze coater, reverse coater, transfer roll coater, gravure coater, spray coater, or the like, and usually dried at a temperature of 50 to 130° C. for 1 to 30 minutes to form a dried coating film. There is no particular restriction on the coating film thickness, but it is generally appropriately selected within the range of 0.1 to 100 μm, preferably 0.5 to 50 μm, in terms of the film thickness after drying.

As the carrier film, a plastic film is used, and it is preferable to use a plastic film such as a polyester film such as polyethylene terephthalate, a polyimide film, a polyamideimide film, a polypropylene film, or a polystyrene film. There is no particular restriction on the thickness of the carrier film, but it is generally selected appropriately in the range of 0.1 to 150 μm.

In this case, after forming the coating film on the carrier film, it is preferable to further laminate a peelable cover film on the surface of the coating film for the purpose of preventing dust from adhering to the surface of the coating film. Examples of the peelable cover film that can be used include polyethylene film, polytetrafluoroethylene film, polypropylene film, and surface-treated paper. When peeling off the cover film, the adhesive strength between the coating film and the cover film should be smaller than the adhesive strength between the coating film and the carrier film.

After adjusting the viscosity of the curable composition of the present invention to a suitable viscosity for the coating method using the organic solvent, the composition can be coated on a substrate by a method such as dip coating, flow coating, roll coating, bar coating, screen printing, curtain coating, or die coating, and the organic solvent contained in the composition can be evaporated and dried (pre-dried) at a temperature of about 50°C to 90°C to form a tack-free dry coating film. In the case of a dry film in which the curable composition of the present invention is coated on a carrier film, dried, and wound up as a film, the film can be attached to the substrate by a laminator or the like so that the coating film of the curable composition is in contact with the substrate, and the carrier film can be peeled off to form a coating layer on the substrate.

These coatings can be photocured by irradiating them with active energy rays, or can be thermally cured by heating them to a temperature of 100°C to 250°C to obtain a cured product.

The above-mentioned substrates include printed wiring boards and flexible printed wiring boards with pre-formed circuits, as well as copper-clad laminates such as paper + phenolic resin, paper + epoxy resin, paper + glass cloth + epoxy resin, nonwoven glass cloth + epoxy resin, woven glass cloth + epoxy resin, and glass fiber + polyimide resin.

The volatilization drying carried out after application of the curable composition of the present invention can be carried out by using a method in which hot air in a dryer equipped with a heat source that uses steam for air heating, such as a hot air circulation drying oven, an IR oven, a hot plate, or a convection oven, is brought into countercurrent contact with the substrate, or by spraying the substrate from a nozzle.

The exposure machine used for the 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 irradiates ultraviolet rays in the range of 350 to 450 nm, and further, a direct imaging machine (for example, a direct imaging machine that directly irradiates active energy rays to draw an image based on CAD data from a computer) may also be used. The light source of the direct imaging machine may be one that uses light with a maximum wavelength in the range of 350 to 410 nm. The exposure dose for image formation varies depending on the film thickness, etc., but can generally be within the range of 20 to 1000 mJ/cm ² , preferably 20 to 800 mJ/cm ² .

The development method can be a dipping method, a shower method, a spray method, a brush method, etc., and the developer can be an alkaline aqueous solution such as potassium hydroxide, sodium hydroxide, sodium carbonate, potassium carbonate, sodium phosphate, sodium silicate, ammonia, or amines.

As described above, the dry film and cured product obtained from the curable composition of the present invention have excellent heat resistance, rigidity, adhesion to substrates, and insulation properties, and can be used in a variety of applications, with no particular limitations on the applications. For example, they can be used to create etching resists, solder resists, and marking resists for printed wiring boards, and in particular, because of their improved solderability, they can be suitably used as solder resists, which require high heat resistance.

<Electronic components using the cured product of the curable composition as an insulating cured coating>
When the cured product of the curable composition pattern-printed on the substrate is used as a solder resist, it is heated in a soldering process for mounting components. Soldering may be performed by any of manual soldering, flow soldering, reflow soldering, etc., but in the case of reflow soldering, for example, the solder is preheated at 100°C to 140°C for 1 to 4 hours, and then heated at 240°C to 280°C for about 5 to 20 seconds multiple times (for example, 2 to 4 times) to heat and melt the solder in a reflow process, and after cooling, components are mounted as necessary to complete the electronic component.

The present invention will be specifically explained below with reference to examples, but the present invention is not limited to these examples. In the following, "parts" refers to parts by mass unless otherwise specified.

(Synthesis of alkali-soluble resin)
[Synthesis Example 1]
380 parts of bisphenol F type epoxy resin (epoxy equivalent 950g/eq, softening point 85°C) and 925 parts of epichlorohydrin were dissolved in 462.5 parts of dimethyl sulfoxide, and then 60.9 parts of 98.5% NaOH were added over 100 minutes at 70°C under stirring. After the addition, the reaction was continued for another 3 hours at 70°C. After the reaction was completed, 250 parts of water were added and washed with water. After oil-water separation, most of the dimethyl sulfoxide and excess unreacted epichlorohydrin were distilled and recovered from the oil layer under reduced pressure, and the reaction product containing the remaining by-product salt and dimethyl sulfoxide was dissolved in 750 parts of methyl isobutyl ketone, and 10 parts of 30% NaOH were added and reacted at 70°C for 1 hour. After the reaction was completed, the reaction was washed twice with 200 parts of water. After oil-water separation, methyl isobutyl ketone was distilled and recovered from the oil layer to obtain an epoxy resin (a) with an epoxy equivalent of 310 g/eq and a softening point of 69°C. The obtained epoxy resin (a) was calculated from the epoxy equivalent, and about 5 out of 6.2 alcoholic hydroxyl groups in the starting material bisphenol F type epoxy resin were epoxidized. 310 parts of this epoxy resin (a) and 282 parts of carbitol acetate were charged in a flask, heated to 90°C, stirred, and dissolved. The obtained solution was once cooled to 60°C, and 72 parts (1 mole) of acrylic acid, 0.5 parts of methylhydroquinone, and 2 parts of triphenylphosphine were added, heated to 100°C, and reacted for about 60 hours to obtain a reaction product with an acid value of 0.2 mgKOH/g. 140 parts (0.92 moles) of tetrahydrophthalic anhydride were added to this, heated to 90°C, and reacted to obtain a photosensitive carboxyl group-containing resin varnish (A-1). The resulting carboxyl group-containing resin varnish (A-1) had a solids concentration of 62.5% and an acid value of the solids (mgKOH/g) of 100.

[Synthesis Example 2]
220 parts of cresol novolac epoxy resin (manufactured by Dainippon Ink and Chemicals, Inc., registered trademark "Epiclon" N-695, epoxy equivalent: 220) was placed in a four-neck flask equipped with a stirrer and a reflux condenser, and 214 parts of carbitol acetate was added and dissolved by heating. Next, 0.1 parts of hydroquinone as a polymerization inhibitor and 2.0 parts of dimethylbenzylamine as a reaction catalyst were added. This mixture was heated to 95 to 105°C, and 72 parts of acrylic acid were gradually added dropwise and reacted for 16 hours. This reaction product was cooled to 80 to 90°C, and 106 parts of tetrahydrophthalic anhydride was added, reacted for 8 hours, cooled, and then taken out.
The photosensitive resin thus obtained, having both an ethylenically unsaturated bond and a carboxyl group, had a non-volatile content of 65%, an acid value of the solid matter of 85 mgKOH/g, and a weight average molecular weight Mw of about 3,500. Hereinafter, this resin solution is referred to as varnish (A-2).
The weight average molecular weight of the resulting resin was measured by high performance liquid chromatography using three connected pumps, LC-804, KF-803 and KF-802, all manufactured by Shimadzu Corporation.

1. Preparation of curable compositions of Examples 1 to 9 and Comparative Examples 1 to 3
The resin solution of the synthesis example and each material shown in Table 1 were mixed, premixed with a stirrer, and then kneaded with a three-roll mill to prepare a curable composition. In Table 1, (A-1) to (A-3) indicate the parts by mass of each resin solution including a solvent.

The following characteristic tests were carried out on each of the above compositions. The results are shown in Table 1.

2. Evaluation of repellency and leveling properties of curable composition on substrate
Each of the curable compositions prepared in <1. Preparation of curable compositions of Examples 1 to 9 and Comparative Examples 1 to 3> was printed on a copper-clad substrate (base material) whose surface had been roughened by chemical polishing treatment using a screen (Tetron 100 mesh) to a film thickness of 10 μm over the entire surface of the copper-clad substrate.

The coating film immediately after printing was visually observed to confirm the presence or absence of repellency of the curable composition and the leveling state (smoothness). The printed substrate was then dried at 80°C for 30 minutes, and after returning to room temperature, the coating film state after drying was similarly visually confirmed. (Note that, although visual confirmation was used in this example, if visual judgment is difficult, the surface roughness may be observed using a surface roughness measuring device (Surfcorder: manufactured by Kosaka Laboratory Co., Ltd.) or a shape measuring laser microscope (VK-X-100/manufactured by KEYENCE Corporation).)
The evaluation criteria are as follows:

○: No repelling, no mesh marks △: Repelling, no mesh marks, or no repelling, mesh marks ×: Repelling, mesh marks

<3. Evaluation of flux repellency>
Using a screen (Tetron 100 mesh), each of the curable compositions prepared in <1. Preparation of curable compositions of Examples 1 to 4 and Comparative Examples 1 to 4> was printed to a film thickness of 10 μm on the entire surface of an FR-4, 35 μm-thick copper-clad laminate having an outer dimension of 150 × 95 mm and a thickness of 1.6 mm and having a surface roughened by chemical polishing treatment.

After drying at 80°C for 30 minutes, the film was exposed to light at 600 mJ/ ^cm2 using an exposure mask measuring 95 x 150 mm to form a pattern, and then alkaline development (1% _{Na2O3 aq} , development at 30°C for 60 seconds) was performed. After thermal curing at 150°C for 60 minutes, post-UV treatment was performed at 1000 mJ/ ^cm2 .

An FR-4 substrate (base material) with the cured product of the curable composition fixed thereto was subjected to electroless Sn plating (Sn: 1.1 μm/Tsukada Riken Kogyo Co., Ltd.), and the reflow process (265°C) was repeated from one to three times. After the electroless Sn plating, a wet tension test was performed on the FR-4 substrate with the cured product of the curable composition fixed thereto at each stage: before the reflow process, after the first reflow process, after the second reflow process, and after the third reflow process.

The wet tension test was performed based on JIS K6768, and the wet tension test mixture used was "Wet Tension Test Mixture No. 60.0" before the reflow process after electroless Sn plating, "Wet Tension Test Mixture No. 38.0" after one reflow process, "Wet Tension Test Mixture No. 36.0" after two reflow processes, and "Wet Tension Test Mixture No. 34.0" after three reflow processes. All wet tension test mixtures were manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. The No. of each mixture indicates the surface tension of the mixture (unit: mN/m).

Specifically, the wetting tension test involved tracing the substrate with a cotton swab containing the mixture for the wetting tension test, and observing the state of the liquid film after two seconds. If the liquid film did not break and maintained the same state as when it was applied for two seconds or more, it was determined to be wet.

The larger the No. number of the mixture for the wetting tension test, the more difficult it is to wet, so the wetting tension test is a test to evaluate flux repellency (flux wettability).

In Table 1, the evaluation criteria are as follows:

○: It is judged to be wet (no repelling) at all stages from before the reflow process after electroless Sn plating to after the third reflow process.

×: After electroless Sn plating, it may be determined that the surface is not wetted (repellent) even once out of the period before the reflow process and after three reflow processes.

*1: Cyclomer P (ACA) Z250 (unsaturated group-containing carboxyl group-containing copolymer resin solution with 45 wt% solids, manufactured by Daicel Chemical Industries, Ltd.)
*2: 2,4,6-trimethylbenzoyldiphenylphosphine oxide (Omnirad TPO H: manufactured by IGM Resins B.V.)
*3: 2-Dimethylamino-2-(4-methyl-benzyl)-1-(4-morpholin-4-yl-phenyl)-butan-1-one (Omnirad 379: manufactured by IGM Resins B.V.)
*4: Bisphenol A type epoxy resin (JER (registered trademark)-834: manufactured by Mitsubishi Chemical Corporation)
*5: Triglycidyl isocyanurate (TEPIC-HP: manufactured by Nissan Chemical Industries, Ltd.)
*6: Polyester modified polydimethylsiloxane (BYK (registered trademark)-313: manufactured by BYK Japan)
*7: Polyether modified polydimethylsiloxane (BYK (registered trademark)-300: manufactured by BYK Japan)
*8: Spherical silica (D50 = 0.6 μm) (SFP-130MC: manufactured by Denki Kagaku Kogyo Co., Ltd.)
*9: Spherical silica (D50 = 0.4 μm) (SFP-20M: manufactured by Denki Kagaku Kogyo Co., Ltd.)
*10: Polyhydroxycarboxylic acid ester (BYK (registered trademark)-R 606: manufactured by BYK Japan)
*11: Melamine (Melamine: Nissan Chemical Industries, Ltd.)
*12: Spherical silica with a methacrylsilane-treated surface (1.5 μm SM-C4: manufactured by Admatechs Co., Ltd.)
*13: Dipentaerythritol hexaacrylate (DPHA: manufactured by Nippon Kayaku Co., Ltd.)
*14: Dicyandiamide (DICY7: manufactured by Mitsubishi Chemical Corporation)
*15: Blue pigment (Firstgen Blue 5380: manufactured by DIC Corporation). Table 1 indicates the mass parts of solid content.
*16: Yellow pigment (Cromophtal (registered trademark) Yellow S1515: manufactured by BASF), Table 1 indicates the mass parts of solid content.

*17: Dipropylene glycol methyl ether (Dowanol (registered trademark) DPM: manufactured by Dow Chemical Japan)

As shown in the examples in Table 1, when (D) a silicone compound, (E) hydrophilic silica, and (F) an organic thixotropic agent are blended, the wettability of the curable composition of the present invention to a copper-clad substrate (substrate) is maintained, the leveling property is also good, and (E) hydrophilic silica does not aggregate or precipitate. In addition, even when the mixture for the wetting tension test is applied to a substrate to which a cured product of the curable composition of the present invention is fixed, the mixture for the wetting tension test is not repelled by the cured product, and the wettability of the mixture for the wetting tension test to the cured product is maintained.

On the other hand, in Comparative Example 1, in which the surface of the silica was hydrophobically treated, the wettability of the mixture for the wetting tension test to the substrate on which the cured product of the curable composition was fixed was reduced even though the organic thixotropic agent (F) was blended, and it was considered that the solderability was reduced. In Comparative Example 2, which did not contain the organic thixotropic agent (F), the wettability of the mixture for the wetting tension test to the substrate on which the cured product of the curable composition was fixed was reduced even though the silicone compound (D) and hydrophilic silica (E) were blended, and it was considered that the solderability was reduced. Furthermore, in Comparative Example 3, which did not contain the silicone compound (D), the wettability of the curable composition to the copper-clad substrate (substrate) was insufficient, or the leveling property was deteriorated.

Claims (9)

(A) an alkali-soluble resin;
(B) a photopolymerization initiator;
(C) an epoxy resin;
(D) a silicone compound;
(E) hydrophilic silica; and
(F) an organic thixotropic agent;
Including,
The (F) organic thixotropic agent is a polyhydroxycarboxylic acid ester,
the amount of the hydrophilic silica (E) is in the range of 20 parts by mass or more and 200 parts by mass or less per 100 parts by mass of the alkali-soluble resin (A);
(E) A curable composition characterized in that the median diameter D50 of hydrophilic silica is 5.0 μm or less . The curable composition according to claim 1, characterized in that the hydrophilic silica (E) has a median diameter D50 of 2.0 μm or less. The curable composition according to claim 1, characterized in that the hydrophilic silica (E) has a median diameter D50 of 0.2 μm or more. The curable composition according to claim 1, characterized in that the median diameter D50 of the hydrophilic silica (E) is 0.2 μm or more and 2.0 μm or less. The curable composition according to any one of claims 1 to 4, characterized in that the amount of the organic thixotropic agent (F) is 0.01 parts by mass or more and 15 parts by mass or less per 100 parts by mass of the hydrophilic silica (E), and is 0.05 parts by mass or more per 2 parts by mass of the silicone compound (D). The curable composition according to any one of claims 1 to 5 , further comprising (G) an antioxidant. A dry film obtained by applying the curable composition according to any one of claims 1 to 6 onto a carrier film and drying the applied composition. A cured product obtained by curing a dried coating film obtained by applying the curable composition according to any one of claims 1 to 7 onto a substrate and drying the same, or a coating film obtained by applying the curable composition onto a carrier film and drying the same to a substrate and laminating the resulting dry film on the substrate. An electronic component comprising the cured product according to claim 8 .