JP7542325B2 - CURABLE RESIN COMPOSITION, DRY FILM, CURED PRODUCT, AND ELECTRONIC COMPONENT - Google Patents

Description

The present invention relates to a curable resin composition, a dry film, a cured product, and an electronic component.

Conventionally, multilayer printed wiring boards have been known in which multiple circuit boards with circuits formed thereon are laminated and pressed together with prepreg interlayer insulating material between them, and the circuits on each layer are connected by through holes. Also known is a build-up printed wiring board in which interlayer insulating material and conductor layers are alternately stacked on the conductor layer of an inner layer circuit board (see, for example, Patent Documents 1 and 2).

Generally, a thermosetting interlayer insulating film is used as the interlayer insulating material, and via openings for interlayer connection are formed by laser processing such as a _CO2 laser. However, since laser processing does not allow a large number of via openings to be formed at once, a photosensitive interlayer insulating material that can be used with photolithography technology is required.

On the other hand, wafer-level packaging is known as one type of packaging format for semiconductor components. When manufacturing wafer-level packaging, there is an increasing demand for alkaline-developable photosensitive insulating materials in order to form fine insulating patterns all at once.

JP 2006-182991 A (Claims, etc.) JP 2013-36042 A (Claims, etc.)

In electronic components such as those described above, there is a demand for high-density wiring, and improving the resolution of photosensitive insulating materials is an issue. The inventors have noticed that the resolution can be improved by blending silica with a small maximum particle size as an inorganic filler. However, they have found that cured films containing silica with such small particle sizes have poor resistance to chemicals such as acetone, and are prone to cracking.

The object of the present invention is to provide a photosensitive curable resin composition capable of forming a cured product having excellent resolution and excellent chemical resistance, a dry film having a resin layer obtained from the composition, a cured product of the composition or the resin layer of the dry film, and an electronic component having the cured product.

As a result of intensive research into achieving the above object, the inventors discovered that the above problem could be solved by blending silica with a smaller maximum particle size and setting the ratio of the carboxyl groups of the carboxyl group-containing resin to the epoxy groups of the epoxy resin contained in the composition within a specific range, thereby completing the present invention.

That is, the curable resin composition of the present invention is a curable resin composition containing (A) a carboxyl group-containing resin, (B) a photopolymerization initiator, (C) an epoxy resin, and (D) silica, characterized in that the (D) silica does not contain silica with a particle size of more than 300 nm, and the ratio of epoxy groups of the (C) epoxy resin to carboxyl groups of the (A) carboxyl group-containing resin is 1.9 to 2.9.

In the curable resin composition of the present invention, the content of the (D) silica is preferably 5 to 35 mass % based on the total solid content of the composition.

In the curable resin composition of the present invention, the epoxy resin (C) is preferably composed solely of an epoxy resin having an epoxy equivalent of 100 to 250 g/eq.

The dry film of the present invention is characterized by having a resin layer obtained by applying the curable resin composition onto a film and drying it.

The cured product of the present invention is characterized by being obtained by curing the curable resin composition or the resin layer of the dry film.

The electronic component of the present invention is characterized by having the above-mentioned cured product.

The present invention provides a photosensitive curable resin composition capable of forming a cured product having excellent resolution and chemical resistance, a dry film having a resin layer obtained from the composition, a cured product of the composition or the resin layer of the dry film, and an electronic component having the cured product.

The curable resin composition of the present invention is a curable resin composition containing (A) a carboxyl group-containing resin, (B) a photopolymerization initiator, (C) an epoxy resin, and (D) silica, characterized in that the (D) silica does not contain silica with a particle diameter of more than 300 nm, and the ratio of epoxy groups of the (C) epoxy resin to carboxyl groups of the (A) carboxyl group-containing resin is 1.9 to 2.9.

In the present invention, it is essential that the silica (D) does not contain silica with a particle size exceeding 300 nm. For example, as shown in Comparative Example 1 described later, resolution can be improved even with silica that is not as small in particle size, but in that case, even if the epoxy group/carboxyl group ratio is as described above, the effect of improving chemical resistance cannot be obtained.

In the present invention, "containing no silica with a particle diameter of more than 300 nm," the "particle diameter" includes not only the particle diameter of primary particles but also the particle diameter of secondary particles (aggregates), and is a value measured by dynamic light scattering. An example of a measuring device using dynamic light scattering is the NanotracWave II UT151 manufactured by Microtrac Bell.

In the present invention, the ratio of epoxy groups in the (C) epoxy resin to carboxyl groups in the (A) carboxyl group-containing resin is the ratio between the number of epoxy groups in the (C) epoxy resin contained in the composition and the number of carboxyl groups in the (A) carboxyl group-containing resin. The ratio of epoxy groups in the (C) epoxy resin to carboxyl groups in the (A) carboxyl group-containing resin is preferably 1.9 to 2.6.

(C) The epoxy resin preferably consists of only an epoxy resin having an epoxy equivalent of 100 to 250 g/eq., which provides better resolution and chemical resistance.

Each component of the curable resin composition of the present invention is described in detail below.

[(A) Carboxyl group-containing resin]
As the (A) carboxyl group-containing resin, various known carboxyl group-containing resins having carboxyl groups in the molecule can be used. In particular, a carboxyl group-containing photosensitive resin having an ethylenically unsaturated group in the molecule is preferred from the viewpoint of photocurability and development resistance. The ethylenically unsaturated group is preferably derived from acrylic acid or methacrylic acid or a derivative thereof. When using only a carboxyl group-containing resin that does not have an ethylenically unsaturated group, in order to make the composition photocurable, it is necessary to use a compound having a plurality of ethylenically unsaturated groups in the molecule, i.e., a photoreactive monomer, which will be described later.

Specific examples of carboxyl group-containing resins include the compounds (which may be either oligomers or polymers) listed below. Note that in this specification, (meth)acrylate is a general term for acrylate, methacrylate, and mixtures thereof, and the same applies to other similar expressions.

(1) A carboxyl group-containing resin obtained by copolymerizing an unsaturated carboxylic acid such as (meth)acrylic acid with an unsaturated group-containing compound such as styrene, α-methylstyrene, lower alkyl (meth)acrylate, or isobutylene.

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

(3) A urethane resin containing terminal carboxyl groups, which is obtained by reacting an acid anhydride with the terminal of a urethane resin obtained by polyaddition reaction of a diisocyanate compound such as an aliphatic diisocyanate, a branched aliphatic diisocyanate, an alicyclic diisocyanate, or an aromatic diisocyanate with a diol compound such as a polycarbonate polyol, a polyether polyol, a polyester polyol, a polyolefin polyol, an acrylic polyol, a bisphenol A alkylene oxide adduct diol, or a compound having a phenolic hydroxyl group or an alcoholic hydroxyl group.

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

(5) A carboxyl group-containing urethane resin that is (meth)acrylated at the terminal by adding a compound having one hydroxyl group and one or more (meth)acryloyl groups in the molecule, such as hydroxyalkyl (meth)acrylate, during the synthesis of the resin (2) or (4) above.

(6) A carboxyl group-containing urethane resin that is (meth)acrylated at the terminal by adding a compound having one isocyanate group and one or more (meth)acryloyl groups in the molecule, such as an equimolar reactant of isophorone diisocyanate and pentaerythritol triacrylate, during the synthesis of the resin (2) or (4) above.

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

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

(9) A carboxyl group-containing polyester resin obtained by reacting a polyfunctional oxetane resin with a dicarboxylic acid and adding a dibasic acid anhydride to the resulting primary hydroxyl groups.

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

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

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

(13) A carboxyl group-containing resin having at least one of an amide structure and an imide structure.

(14) A carboxyl group-containing resin obtained by further adding a compound having one epoxy group and one or more (meth)acryloyl groups in the molecule, such as glycidyl (meth)acrylate, α-methylglycidyl (meth)acrylate, or 3,4-epoxycyclohexylmethyl methacrylate, to the carboxyl group-containing resin described in (1) to (13) above.

Among the above carboxyl group-containing resins, it is preferable to include at least one of the carboxyl group-containing resins described in (7), (8), (10), (11), and (14) above. From the viewpoint of further improving the insulation reliability, it is preferable to include the carboxyl group-containing resins described in (10) and (11) above.

(A) The carboxyl group-containing resin may be used alone or in the form of a mixture of two or more types.

The acid value of the (A) carboxyl group-containing resin is preferably in the range of 20 to 120 mgKOH/g, more preferably in the range of 30 to 100 mgKOH/g. By setting the acid value of the (A) carboxyl group-containing resin in the above range, good alkaline development is possible, and a normal cured pattern can be formed. The weight average molecular weight of the (A) carboxyl group-containing resin varies depending on the resin skeleton, but is generally preferably 2,000 to 150,000. When the weight average molecular weight is 2,000 or more, the tack-free property of the dried coating film, the moisture resistance of the coating film after exposure, and the resolution are good. On the other hand, when the weight average molecular weight is 150,000 or less, the developability and storage stability are good. It is more preferably 5,000 to 100,000.

[(B) Photopolymerization initiator]
As the photopolymerization initiator (B), any photopolymerization initiator known as a photopolymerization initiator or a photoradical generator can be used. For example, 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 and other bisacylphosphine oxides; 2,6-dimethoxybenzoyldiphenylphosphine oxide, 2,6-dichlorobenzoyldiphenylphosphine oxide, 2,4,6- Monoacylphosphine oxides such as trimethylbenzoylphenylphosphinic acid methyl ester, 2-methylbenzoyldiphenylphosphine oxide, pivaloylphenylphosphinic acid isopropyl ester, and 2,4,6-trimethylbenzoyldiphenylphosphine oxide; hydroxyacetophenones 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-propan-1-one, and 2-hydroxy-2-methyl-1-phenylpropan-1-one; benzoin, benzil, benzoin methyl ether, benzoin ethyl ether, benzoin n-propyl ether, benzoin isopropyl ether, and benzoin n-butyl ether; benzoin alkyl ethers; benzophenones such as benzophenone, p-methylbenzophenone, Michler's ketone, methylbenzophenone, 4,4'-dichlorobenzophenone, and 4,4'-bisdiethylaminobenzophenone; acetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, 1,1-dichloroacetophenone, 1-hydroxycyclohexyl phenyl ketone, 2-methyl acetophenones such as 1-[4-(methylthio)phenyl]-2-morpholino-1-propanone, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1, 2-(dimethylamino)-2-[(4-methylphenyl)methyl]-1-[4-(4-morpholinyl)phenyl]-1-butanone, and N,N-dimethylaminoacetophenone; thioxanthone, 2-ethylthioxanthone, 2-isopropylthioxanthone, 2, Thioxanthones such as 4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2-chlorothioxanthone, and 2,4-diisopropylthioxanthone; anthraquinones such as anthraquinone, chloroanthraquinone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-tert-butylanthraquinone, 1-chloroanthraquinone, 2-amylanthraquinone, and 2-aminoanthraquinone; acetophenone dimethyl ketal, benzyl dithioxanthone, and the like. Ketals such as methyl ketal; benzoic acid esters such as ethyl-4-dimethylaminobenzoate, 2-(dimethylamino)ethyl benzoate, and p-dimethylbenzoic acid ethyl ester; oxime esters such as 1,2-octanedione, 1-[4-(phenylthio)-, 2-(O-benzoyloxime)], ethanone, 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]-, and 1-(O-acetyloxime); bis(η ^5-2,4 -cyclopentadien-1-yl)-bis(2,6-difluoro-3-(1H-pyrrol-1-yl)phenyl)titanium, bis(cyclopentadienyl)-bis[2,6-difluoro-3-(2-(1-pyrrol-1-yl)ethyl)phenyl]titanium and other titanocenes; phenyl disulfide 2-nitrofluorene, butyroin, anisoin ethyl ether, azobisisobutyronitrile, tetramethylthiuram disulfide and the like can be mentioned. Among the (B) photopolymerization initiators, it is preferable to contain an acylphosphine-based photopolymerization initiator such as bisacylphosphine oxides or monoacylphosphine oxides in order to increase the exposure sensitivity. The (B) photopolymerization initiator may be used alone or in combination of two or more.

The amount of (B) photopolymerization initiator is preferably 0.5 to 20 parts by weight per 100 parts by weight of (A) carboxyl group-containing resin. If it is 0.5 parts by weight or more, the surface curing property is good, and if it is 20 parts by weight or less, halation is unlikely to occur and good resolution can be obtained.

[(C) Epoxy resin]
As the epoxy resin (C), a known and commonly used epoxy resin can be used, and a polyfunctional epoxy resin having two or more epoxy groups is preferable. The epoxy resin may be liquid, solid, or semi-solid. Examples of the polyfunctional epoxy resin include, but are not limited to, bisphenol A type epoxy resin, brominated epoxy resin, novolac type epoxy resin, bisphenol F type epoxy resin, hydrogenated bisphenol A type epoxy resin, glycidylamine type epoxy resin, hydantoin type epoxy resin, alicyclic epoxy resin, trihydroxyphenylmethane type epoxy resin, bixylenol type or biphenol type epoxy resin or mixture thereof, bisphenol S type epoxy resin, bisphenol A novolac type epoxy resin, tetraphenylolethane type epoxy resin, heterocyclic epoxy resin, diglycidyl phthalate resin, tetraglycidyl xylenoylethane resin, naphthalene group-containing epoxy resin, dicyclopentadiene type epoxy resin, glycidyl methacrylate copolymer epoxy resin, cyclohexylmaleimide and glycidyl methacrylate copolymer epoxy resin, epoxy-modified polybutadiene rubber derivative, CTBN-modified epoxy resin, etc. (C) The epoxy resin may be used alone or in combination of two or more. The epoxy resin (C) is preferably a bisphenol A or bisphenol F novolac type epoxy resin, a bixylenol type epoxy resin, a biphenol type epoxy resin, a biphenol novolac type (biphenyl aralkyl type) epoxy resin, a naphthalene type epoxy resin, a dicyclopentadiene type epoxy resin, or a mixture thereof.

(C) The epoxy equivalent of the epoxy resin is preferably 100 to 300 g/eq., and more preferably 100 to 250 g/eq.

[(D) Silica]
The curable resin composition of the present invention contains (D) silica as a filler component, but does not contain silica having a particle size of more than 300 nm. By containing silica, a cured product having a small linear expansion coefficient can be obtained. Examples of silica include fused silica, spherical silica, amorphous silica, crystalline silica, etc., and among them, spherical silica is preferable. The method for producing (D) silica is not particularly limited, but the sol-gel method is preferable because it can produce silica with a small maximum particle size.

The maximum particle size of (D) silica is 300 nm or less, preferably 280 nm or less. The average particle size (D50, median size) of (D) silica is preferably 120 nm or less, more preferably 60 nm or less, and even more preferably 30 nm or less.

(D) Silica is preferably surface-treated silica. Here, surface treatment refers to a treatment for improving compatibility with the resin component. In addition, a surface treatment capable of introducing a curable reactive group may be applied to the surface of the silica. Here, the curable reactive group is not particularly limited as long as it is a group that undergoes a curing reaction with a curable compound such as (A) a carboxyl group-containing resin or (C) an epoxy resin, and may be a photocurable reactive group or a thermosetting reactive group. Examples of photocurable reactive groups include methacrylic groups, acrylic groups, vinyl groups, and styryl groups, and examples of thermosetting reactive groups include epoxy groups, amino groups, hydroxyl groups, carboxyl groups, isocyanate groups, imino groups, oxetanyl groups, mercapto groups, methoxymethyl groups, methoxyethyl groups, ethoxymethyl groups, ethoxyethyl groups, and oxazoline groups. The method for introducing a curable reactive group onto the surface of silica is not particularly limited, and may be introduced using a known, commonly used method, and the surface of the silica may be treated with a surface treatment agent having a curable reactive group, for example, a coupling agent having a curable reactive group as an organic group. Examples of the coupling agent that can be used include a silane coupling agent, a titanium coupling agent, a zirconium coupling agent, and an aluminum coupling agent. Examples of surface-treated silica that does not have a curable reactive group include silica-alumina surface treatment, titanate-based coupling agent treatment, aluminate-based coupling agent treatment, and organically treated silica.

The method for adjusting the average particle size of (D) silica is not particularly limited, but it is preferable to pre-disperse it with a bead mill or a jet mill, for example. In addition, as (D) silica, commercially available products whose maximum particle size and average particle size are within the above ranges may be used as they are. Commercially available products include QSG-10 (average particle size 15 nm, maximum particle size 40 nm), QSG-30 (average particle size 30 nm, maximum particle size 70 nm), and QSG-100 (average particle size 110 nm, maximum particle size 270 nm) manufactured by Shin-Etsu Chemical Co., Ltd., PGM-AC-2140Y (propylene glycol monomethyl ether dispersed silica, solid content concentration 42 mass%, average particle size 12 nm, maximum particle size 30 nm), and MEK-EC-2130Y (methyl ethyl ketone dispersed silica, solid content concentration 30 mass%, average particle size 12 nm). m, maximum particle size 30 nm), MEK-EC2430Z (silica dispersed in methyl ethyl ketone, solid content concentration 30 mass%, average particle size 12 nm, maximum particle size 30 nm), PMA-ST (silica dispersed in propylene glycol monomethyl ether, solid content concentration 30 mass%, average particle size 12 nm, maximum particle size 30 nm), and Admatechs' YA050C-LHQ (silica dispersed in propylene glycol monomethyl ether acetate, solid content concentration 40 mass%, average particle size 50 nm, maximum particle size 180 nm).

(D) Silica may be blended in a slurry state. Blending in a slurry state facilitates high dispersion, prevents aggregation, and makes it easy to handle silica with the maximum particle size within the above specified range.

One type of (D) silica may be used alone, or two or more types may be used in combination. The amount of (D) silica is preferably 5 to 35 mass% based on the total solid content of the composition, and more preferably 10 to 30 mass%. When the amount of (D) silica is within the above range, the resolution is better.

(Compound having an ethylenically unsaturated group)
The curable resin composition of the present invention may contain a compound having an ethylenically unsaturated group. The compound having an ethylenically unsaturated group is photocured by irradiation with active energy rays, and can insolubilize or help insolubilize the irradiated portion of the resin layer in an alkaline aqueous solution. As the compound having an ethylenically unsaturated group, a photopolymerizable oligomer, a photopolymerizable vinyl monomer, etc., which are known and commonly used photosensitive monomers, can be used. As the compound having an ethylenically unsaturated group, a photosensitive (meth)acrylate compound can be used. The compound having an ethylenically unsaturated group may be used alone or in combination of two or more. In this specification, the term "compound having an ethylenically unsaturated group" does not include a carboxyl group-containing resin having an ethylenically unsaturated group.

Examples of the compound having an ethylenically unsaturated group include commonly known polyester (meth)acrylates, polyether (meth)acrylates, urethane (meth)acrylates, carbonate (meth)acrylates, epoxy (meth)acrylates, and urethane (meth)acrylates. Specific examples of the compound having an ethylenically unsaturated group include hydroxyalkyl acrylates such as 2-hydroxyethyl acrylate and 2-hydroxypropyl acrylate; diacrylates of glycols such as ethylene glycol, methoxytetraethylene glycol, polyethylene glycol, and propylene 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; hexanediol, trimethylolpropane, pentaerythritol, dipentaerythritol, tris-hydroxyethyl Examples of the polyhydric alcohol include polyhydric alcohols such as polyisocyanurate, and their ethylene oxide adducts, propylene oxide adducts, and ε-caprolactone adducts; polyhydric acrylates such as phenoxy acrylate, bisphenol A diacrylate, and their ethylene oxide adducts or propylene oxide adducts; polyhydric acrylates of glycidyl ethers such as glycerin diglycidyl ether, glycerin triglycidyl ether, trimethylolpropane triglycidyl ether, and triglycidyl isocyanurate; and, without being limited to the above, acrylates and melamine acrylates obtained by directly acrilating polyols such as polyether polyols, polycarbonate diols, hydroxyl group-terminated polybutadienes, and polyester polyols, or by urethane acrylate via diisocyanates, and at least one of the methacrylates corresponding to the above acrylates.

Further examples include epoxy acrylate resins obtained by reacting acrylic acid with multifunctional epoxy resins such as cresol novolac epoxy resins, and epoxy urethane acrylate compounds obtained by reacting the hydroxyl groups of the epoxy acrylate resins with half urethane compounds of hydroxyacrylates such as pentaerythritol triacrylate and diisocyanates such as isophorone diisocyanate. Such epoxy acrylate resins can improve photocurability without reducing tactile dryness.

The amount of the compound having an ethylenically unsaturated group is preferably 1 to 60 parts by mass, more preferably 5 to 55 parts by mass, and even more preferably 10 to 50 parts by mass per 100 parts by mass of the carboxyl group-containing resin (A). By keeping the amount within the above range, it is possible to obtain good photoreactivity and heat resistance.

(Thermal curing accelerator)
The curable resin composition of the present invention may contain a heat curing accelerator. The heat curing accelerator may be used alone or in combination of two or more.

Examples of thermal curing accelerators include imidazole derivatives such as imidazole, 2-methylimidazole, 2-ethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 4-phenylimidazole, 1-benzyl-2-phenylimidazole, 1-cyanoethyl-2-phenylimidazole, and 1-(2-cyanoethyl)-2-ethyl-4-methylimidazole; amine compounds such as dicyandiamide, benzyldimethylamine, 4-(dimethylamino)-N,N-dimethylbenzylamine, 4-methoxy-N,N-dimethylbenzylamine, and 4-methyl-N,N-dimethylbenzylamine; hydrazine compounds such as adipic acid dihydrazide and sebacic acid dihydrazide; and phosphorus compounds such as triphenylphosphine. In addition to these, S-triazine derivatives such as guanamine, acetoguanamine, benzoguanamine, melamine, 2,4-diamino-6-methacryloyloxyethyl-S-triazine, 2-vinyl-2,4-diamino-S-triazine, 2-vinyl-4,6-diamino-S-triazine-isocyanuric acid adduct, and 2,4-diamino-6-methacryloyloxyethyl-S-triazine-isocyanuric acid adduct can also be used.

Commercially available heat curing accelerators include, for example, 2MZ-A, 2MZ-OK, 2PHZ, 1B2PZ, 2P4BHZ, and 2P4MHZ (all trade names for imidazole-based compounds) manufactured by Shikoku Chemical Industry Co., Ltd., and U-CAT3503N and U-CAT3502T (all trade names for dimethylamine blocked isocyanate compounds), DBU, DBN, U-CATSA102, and U-CAT5002 (all bicyclic amidine compounds and their salts) manufactured by San-Apro Co., Ltd.

The amount of the heat curing accelerator is preferably 0.1 to 10 parts by mass, and more preferably 0.1 to 5.0 parts by mass, per 100 parts by mass of the carboxyl group-containing resin (A). If the amount is 0.1 part by mass or more, the heat resistance of the cured product will be good, and if it is 10 parts by mass or less, the storage stability will be good.

(Organic Solvent)
In the curable resin composition of the present invention, an organic solvent can be used for preparing the resin composition or for adjusting the viscosity for application to a substrate or a carrier film. Examples of such organic solvents include ketones, aromatic hydrocarbons, glycol ethers, glycol ether acetates, esters, alcohols, aliphatic hydrocarbons, and petroleum-based solvents. More specifically, the organic solvents include ketones such as methyl ethyl ketone and cyclohexanone; aromatic hydrocarbons such as toluene, xylene, and tetramethylbenzene; glycol ethers such as cellosolve, methyl cellosolve, butyl cellosolve, carbitol, methyl carbitol, butyl carbitol, propylene glycol monomethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol diethyl ether, and triethylene glycol monoethyl ether; esters such as ethyl acetate, butyl acetate, dipropylene glycol methyl ether acetate, propylene glycol methyl ether acetate, propylene glycol ethyl ether acetate, and propylene glycol butyl ether acetate; alcohols such as ethanol, propanol, ethylene glycol, and propylene glycol; aliphatic hydrocarbons such as octane and decane; and petroleum-based solvents such as petroleum ether, petroleum naphtha, hydrogenated petroleum naphtha, and solvent naphtha. The organic solvents may be used alone or in combination of two or more.

(Other optional ingredients)
The curable resin composition of the present invention may contain other additives that are well known and commonly used in the field of electronic materials. Examples of other additives include thermal polymerization inhibitors, ultraviolet absorbers, coupling agents, plasticizers, flame retardants, antistatic agents, antiaging agents, antibacterial and antifungal agents, defoamers, leveling agents, thickeners, adhesion agents, thixotropy agents, colorants, photoinitiator assistants, sensitizers, curing agents, thermoplastic resins, organic fillers, release agents, surface treatment agents, dispersants, dispersion assistants, surface modifiers, stabilizers, and phosphors.

The curable resin composition of the present invention is suitable for forming an insulating cured coating for a printed wiring board, more suitable for forming an insulating permanent coating, and further suitable for forming a coverlay, solder resist, and interlayer insulating material, and particularly suitable for forming an interlayer insulating material. It is also suitable for forming a permanent coating (particularly an interlayer insulating material) for a printed wiring board that requires high reliability, such as a package substrate, and particularly for FC-BGA, which requires high reliability. The curable resin composition of the present invention can also be used to form a solder dam, etc. The electronic component may be used for purposes other than a printed wiring board, such as a passive component such as an inductor. The curable resin composition of the present invention may be a liquid type or a dry film type obtained by drying a liquid type resin composition. The liquid type resin composition may be a two-component type from the viewpoint of storage stability, but may also be a one-component type.

[Dry film]
The dry film of the present invention has a resin layer obtained by applying the curable resin composition of the present invention onto a film (hereinafter also referred to as a "carrier film") and then drying it. The dry film of the present invention is prepared by diluting the curable resin composition of the present invention with an organic solvent to adjust it to an appropriate viscosity, and coating the curable resin composition with a comma coater, blade coater, lip coater, rod coater, squeeze coater, reverse coater, transfer roll coater, gravure coater, or the like.
The coating can be applied to a uniform thickness on a carrier film using a spray coater or the like, and then dried for 1 to 30 minutes at a temperature of 50 to 120° C. There are no particular limitations on the coating thickness, but the coating thickness after drying is generally set appropriately within the range of 5 to 150 μm, preferably 10 to 60 μm. The film is not limited to a carrier film, and may be a cover film.

As the carrier film, a plastic film can be suitably used, and it is preferable to use a plastic film such as a polyester film such as polyethylene terephthalate, a polyimide film, a polyamideimide film, a polypropylene film, 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 10 to 150 μm.

After the curable resin composition of the present invention is applied onto the carrier film, a peelable cover film may be laminated on the surface of the 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, and any film may be used as long as the adhesive strength between the film and the cover film is smaller than the adhesive strength between the film and the carrier film when the cover film is peeled off.

The volatilization drying carried out after the curable resin composition of the present invention is applied onto a carrier film can be carried out using a hot air circulation drying oven, an IR oven, a hot plate, a convection oven, etc. (a method in which hot air in the dryer is brought into countercurrent contact with the heat source equipped with an air heating method using steam, or a method in which hot air is blown onto the support from a nozzle).

[Cured product]
The cured product of the present invention is obtained by curing the curable resin composition of the present invention, and is obtained by curing the resin layer of the dry film of the present invention.

[Electronic Components]
The electronic component of the present invention is provided with the cured product of the present invention. The electronic component of the present invention can be obtained by a method of directly applying the curable resin composition of the present invention and a method of using the dry film of the present invention. Hereinafter, the case of producing a printed wiring board as an electronic component will be described as an example, but the present invention is not limited thereto.

When a printed wiring board is manufactured by the direct coating method, the curable resin composition of the present invention is directly coated on a printed wiring board on which a circuit is formed, and a coating film of the resin composition is formed. After that, the active energy ray such as a laser beam is directly irradiated according to the pattern, or the active energy ray is selectively irradiated through a photomask on which a pattern is formed, and the unexposed part is developed with a dilute alkaline aqueous solution to form a pattern. Furthermore, the formed pattern is irradiated with an active energy ray at, for example, 100 to 2000 mJ/cm ² , and cured by heating to a temperature of, for example, about 140 to 200° C., to manufacture a printed wiring board having a pattern of the cured product. The irradiation of the active energy ray to the pattern is performed to almost completely cure the photocurable component that did not react by exposure when forming the image.

When a dry film is used, the dry film of the present invention is laminated on a printed wiring board on which a circuit is formed to form a resin layer, and then the resin layer is exposed to light in the same manner as above, and the carrier film is peeled off and developed. The resin layer is then irradiated with active energy rays and cured by heating to a temperature of, for example, about 140 to 200° C., to produce a printed wiring board having a pattern of the cured product.

The exposure machine used for irradiating the active energy rays may be a device equipped with a high pressure mercury lamp, an ultra-high pressure mercury lamp, a metal halide lamp, a mercury short arc lamp, or the like, and capable of irradiating active energy rays in the range of 350 to 450 nm. In addition, a direct imaging device such as a direct imaging device that directly draws an image with active energy rays based on CAD data from a computer may also be used. The light source of the direct imaging device may be a mercury short arc lamp, an LED, or any of a gas laser and solid laser as long as it uses a laser light with a maximum wavelength in the range of 350 to 450 nm. The exposure dose for forming an image of a pattern varies depending on the film thickness, etc., but can generally be within the range of 20 to 1500 mJ/cm ² , preferably 20 to 1200 mJ/cm ² .

The development method may be a dipping method, a shower method, a spray method, a brush method, or the like, and the developer may be an alkaline aqueous solution of potassium hydroxide, sodium hydroxide, sodium carbonate, potassium carbonate, sodium phosphate, sodium silicate, ammonia, amines, or the like.

The present invention will be described in more detail below using examples, but the present invention is not limited to the following examples. Note that "parts" and "%" below are all based on mass unless otherwise specified.

[Synthesis of carboxyl group-containing resin]
(Synthesis Example 1: Carboxyl Group-Containing Resin 1)
In an autoclave equipped with a thermometer, a nitrogen introduction device/alkylene oxide introduction device, and a stirrer, 119.4 parts by mass of novolac cresol resin (trade name "Shounol CRG951", manufactured by Aica Kogyo Co., Ltd., OH equivalent: 119.4), 1.19 parts by mass of potassium hydroxide, and 119.4 parts by mass of toluene were introduced, and the inside of the system was replaced with nitrogen while stirring, and the temperature was raised by heating. Next, 63.8 parts by mass of propylene oxide were gradually dropped, and the reaction was carried out for 16 hours at 125 to 132 ° C. and 0 to 4.8 kg / cm ^2. Thereafter, the reaction solution was cooled to room temperature, and 1.56 parts by mass of 89% phosphoric acid was added and mixed to neutralize the potassium hydroxide, and a propylene oxide reaction solution of novolac cresol resin with a solid content of 62.1% and a hydroxyl value of 182.2 mg KOH / g (307.9 g / eq.) was obtained. This was found to have an average of 1.08 moles of propylene oxide added per equivalent of the phenolic hydroxyl group.
293.0 parts by mass of the resulting propylene oxide reaction solution of the novolac cresol resin, 43.2 parts by mass of acrylic acid, 11.53 parts by mass of methanesulfonic acid, 0.18 parts by mass of methylhydroquinone, and 252.9 parts by mass of toluene were introduced into a reactor equipped with a stirrer, a thermometer, and an air inlet tube, and the mixture was reacted at 110 ° C. for 12 hours while blowing air at a rate of 10 ml / min and stirring. Water generated by the reaction was distilled as an azeotrope with toluene, and 12.6 parts by mass of water was distilled. Thereafter, the mixture was cooled to room temperature, and the resulting reaction solution was neutralized with 35.35 parts by mass of a 15% aqueous sodium hydroxide solution, and then washed with water. Thereafter, the toluene was distilled off while replacing it with 118.1 parts by mass of diethylene glycol monoethyl ether acetate in an evaporator, to obtain a novolac acrylate resin solution. Next, 332.5 parts by mass of the obtained novolac type acrylate resin solution and 1.22 parts by mass of triphenylphosphine were introduced into a reactor equipped with a stirrer, a thermometer, and an air inlet tube, and 60.8 parts by mass of tetrahydrophthalic anhydride were gradually added while blowing air at a rate of 10 ml/min and stirring, and the mixture was reacted at 95 to 101° C. for 6 hours, cooled, and then removed. In this way, a solution of photosensitive carboxyl group-containing resin 1 was obtained, having a solid content of 70.6% and an acid value of the solid content of 87.7 mgKOH/g.

(Synthesis Example 2: Carboxyl Group-Containing Resin 2)
650 parts of diethylene glycol monoethyl ether acetate were charged with 1070 parts of orthocresol novolac epoxy resin (DIC Corporation, EPICLONN-695, softening point 95 ° C., epoxy equivalent 214, average functionality 7.6) (glycidyl group number (total number of aromatic rings): 5.0 moles), 360 parts (5.0 moles) of acrylic acid, and 1.5 parts of hydroquinone, and heated to 100 ° C. with stirring to dissolve uniformly. Next, 4.3 parts of triphenylphosphine were charged, heated to 110 ° C. and reacted for 2 hours, and then 1.6 parts of triphenylphosphine were added, heated to 120 ° C., and reacted for another 12 hours. 525 parts of aromatic hydrocarbon (Solvesso 150) and 608 parts (4.0 moles) of tetrahydrophthalic anhydride were charged to the obtained reaction liquid, and reacted at 110 ° C. for 4 hours. Further, 142.0 parts (1.0 mole) of glycidyl methacrylate was added to the resulting reaction solution, and the reaction was carried out at 115° C. for 4 hours to obtain a solution of photosensitive carboxyl group-containing resin 2 having a solid content acid value of 77 mgKOH/g and a solid content of 65%.

[Examples 1 to 8, Reference Example 1, Comparative Examples 1 to 5]
The various components in Table 1 below were mixed in the ratios (parts by mass) shown in the table, premixed with a stirrer, and then kneaded with a bead mill to prepare curable resin compositions. The amount of each component shown in the table is the part by mass of the solid content excluding the solvent.
The stirring conditions of the stirrer were a rotation speed of 800 rpm, a stirring time of 10 min, a stirrer blade of 12 cm, and a conical type K-8 (manufactured by Buehler) was used as the bead mill. The kneading was performed under the conditions of zirconia beads, a rotation speed of 1000 rpm, a discharge amount of 20%, a bead particle size of 0.65 mm, and a filling rate of 88%.
The curable resin compositions prepared above were each applied onto a 38 μm polyester film using an applicator, and dried in a hot air circulation drying oven at 80° C. for 20 minutes to prepare a dry film having a resin layer with a thickness of 10 μm.

<Evaluation of Resolution>
A substrate made of 17 μm-thick electrolytic copper plating on a 1.6 mm-thick copper-clad laminate of FR-4 and 18 μm-thick copper foil was etched to a depth of 1.0 μm using a CZ-8101B process manufactured by MEC Co., Ltd. The dry film thus prepared was laminated on the substrate using a vacuum laminator (CVP-300: manufactured by Nikko Materials Co., Ltd.) in a first chamber at 90° C. under conditions of a vacuum pressure of 3 hPa and a vacuum time of 30 seconds, and then pressed under conditions of a pressure of 0.5 MPa and a press time of 30 seconds.
Next, the polyester film was peeled off, and exposure was performed in each opening pattern using an exposure device equipped with a high-pressure mercury lamp. The exposure amount was adjusted so that the gloss sensitivity was 7 steps using a step tablet (Photec 41 steps). Then, development was performed for 120 seconds using a 1% by mass Na ₂ CO ₃ aqueous solution at 30°C under a spray pressure of 2 kg/cm ^2. The substrate having this cured film was irradiated with ultraviolet light in a UV conveyor furnace under a cumulative exposure amount of 1000 mJ/cm ² , and then heated and cured at 180°C for 60 minutes. The opening diameter of the obtained cured product was observed by SEM, and the occurrence of halation and undercut was evaluated according to the following criteria.
⊚: A good aperture diameter was obtained with an aperture diameter of 8 μm.
◯: A good opening diameter was obtained with an opening diameter of 10 μm.
Δ: A good opening diameter was obtained with an opening diameter of 15 μm.
×: A satisfactory opening diameter was not obtained with an opening diameter of 15 μm.

<Evaluation of Chemical Resistance>
A substrate having a cured film was obtained in the same manner as in the above-mentioned <Evaluation of resolution> test, except that a copper-plated substrate was attached to a 6-inch wafer with a dry film resin layer. The obtained substrate having a cured film was immersed in acetone for 30 minutes, and the occurrence of cracks was confirmed.
⊚: No cracks were generated after immersion in acetone.
○: Discoloration was observed after immersion in acetone, but no cracks were observed.
×: Cracks were partially generated after immersion in acetone.
XX: Cracks occurred over the entire surface of the material after immersion in acetone.

<Evaluation of coefficient of thermal expansion (CTE)>
A substrate having a cured film was obtained in the same manner as in the above <Evaluation of resolution> test, except that the copper-plated substrate was changed to GTS-MP foil (manufactured by Furukawa Circuit Foil Co., Ltd.), a dry film resin layer was attached to the shiny side (copper foil), and the entire surface was exposed to light. The cured film was peeled off from the copper foil and cut to a width of 3 mm and a length of 30 mm. The CTE of this test piece was measured using a TMA (Thermomechanical Analysis) Q400 manufactured by TA Instruments Co., Ltd. The measurement conditions were tensile mode, chuck distance 16 mm, load 50 mN, nitrogen atmosphere, temperature increase from 20 to 300 ° C. at 10 ° C. / min, then temperature decrease from 300 to -40 ° C. at 10 ° C. / min, and further temperature increase from -40 to 300 ° C. at 10 ° C. / min. The coefficient of thermal expansion below Tg (CTEα1) when the temperature was raised from −40 to 300° C. at 10° C./min was obtained.
⊚: CTEα1 is less than 45 ppm.
◯: CTEα1 is 45 ppm or more and less than 55 ppm.
Δ: CTEα1 is 55 ppm or more and less than 65 ppm.
×: CTEα1 is 65 ppm or more.

<Insulation reliability (B-HAST resistance (L/S=10/10 μm))>
A substrate having a comb pattern of L/S=10/10 μm was prepared, and a substrate having a cured film was prepared in the same manner as in the preparation of the substrate for evaluating resolution, except that the entire surface was exposed to light. Then, HAST was performed under the conditions of 130° C., 85% RH, applied voltage of 3.5 V, and measurement in a tank. The evaluation criteria are as follows.
○: No abnormality even after 300 hours.
△: Short circuit occurred after 200 to 300 hours.
x: Short circuit within 200 hours.

<Evaluation of Adhesion>
(Step 1)
A 1.6 mm thick FR-4 copper-clad laminate was completely copper-removed by etching using ferric chloride (hereinafter simply referred to as the "etched-out plate"), and an 18 μm thick electrolytic copper foil, the four sides of which were slightly smaller than those of the first etched-out plate, was fixed with chemical-resistant adhesive tape. In this state, the electrolytic copper foil was exposed except for the areas where the tape was attached. Next, the electrolytic copper foil attached with Etchbond CZ-8101 manufactured by MEC was chemically polished to produce a copper foil-attached substrate.
(Step 2)
The resin layer of the prepared dry film was laminated on the copper foil surface of the copper foil-attached substrate prepared in step 1 using a vacuum laminator (CVP-300: manufactured by Nikko Materials Co., Ltd.) in a first chamber at 90 ° C. under conditions of a vacuum pressure of 3 hPa and a vacuum time of 30 seconds, and then pressed under conditions of a press pressure of 0.5 MPa and a press time of 30 seconds. Next, the obtained evaluation substrate was exposed to 400 mJ / cm ² using an exposure device equipped with a high-pressure mercury lamp, the PET film was peeled off, and a 1 mass% sodium carbonate aqueous solution at 30 ° C. was developed for 120 seconds under conditions of a spray pressure of 0.2 MPa. After development, the substrate was irradiated with ultraviolet light under conditions of an accumulated exposure amount of 1000 mJ / cm ² in a UV conveyor furnace, and then heated at 180 ° C. for 60 minutes to cure, and a test piece in which a cured film of each composition was formed on the copper foil of the copper foil-attached substrate was prepared.
(Step 3)
A second etch-out plate, the four sides of which were slightly smaller than those of the copper foil of the test piece, was adhered to the cured film surface of the test piece prepared in step 2 with a two-liquid epoxy adhesive (Araldite Standard), and cured for 4 hours at 60° C. After curing, the plate was cut out with a cutter to the size of the adhered second etch-out plate, detached from the first etch-out plate, and turned over to prepare a peel strength measurement sample in which chemically polished copper foil was formed on the cured film of each composition adhered to the second etch-out plate.
(measurement)
The prepared peel strength measurement sample was cut into a size of 1 cm width and 7 cm or more length, and the adhesion strength at an angle of 90 degrees was determined using a small tabletop tester EZ-SX manufactured by Shimadzu Corporation and a 90° print peeling jig.
The evaluation criteria are as follows:
◯: Adhesion to the underlying copper is 5 N/cm or more.
Δ: Adhesion to the underlying copper is 3 N/cm or more and less than 5 N/cm.
x: Adhesion to the underlying copper is less than 3 N/cm.

*1: Solution of carboxyl group-containing resin 1 synthesized above (solid content 70.6%, acid value of solid content 87.7 mgKOH/g)
*2: Solution of the carboxyl group-containing resin 2 synthesized above (solid content 65%, solid content acid value 77 mgKOH/g)
*3: Omnirad TPO H (manufactured by IGM Resins)
* 4: Dicyclopentadiene type epoxy resin HP-7200L (epoxy equivalent: 248 g / eq, manufactured by DIC Corporation)
*5: Naphthalene type epoxy resin HP-4032D (epoxy equivalent: 136 g/eq, manufactured by DIC Corporation)
*6: Biphenyl aralkyl type epoxy resin NC-3000H (epoxy equivalent: 286 g/eq, manufactured by Nippon Kayaku Co., Ltd.)
*7: QSG-10 (average particle size 15 nm, maximum particle size 40 nm) manufactured by Shin-Etsu Chemical Co., Ltd. *8: QSG-30 (average particle size 30 nm, maximum particle size 70 nm) manufactured by Shin-Etsu Chemical Co., Ltd. *9: QSG-100 (average particle size 110 nm, maximum particle size 270 nm) manufactured by Shin-Etsu Chemical Co., Ltd. *10: QSG-170 (average particle size 170 nm, maximum particle size 420 nm) manufactured by Shin-Etsu Chemical Co., Ltd. *11: SO-C5 (average particle size 1100 nm, maximum particle size 7000 nm) manufactured by Admatechs Co., Ltd. *12: 1B2PZ (manufactured by Shikoku Chemical Industry Co., Ltd.)
*13: Dipentaerythritol hexaacrylate DPHA (manufactured by Nippon Kayaku Co., Ltd.)
* 14: Ratio of epoxy groups of epoxy resin to carboxyl groups of carboxyl group-containing resin

The results shown in the table above show that the curable resin compositions of Examples 1 to 8 and Reference Example 1 of the present invention have excellent resolution and chemical resistance.

Claims (6)

(A) a carboxyl group-containing resin;
(B) a photopolymerization initiator;
(C) an epoxy resin; and
(D) A curable resin composition comprising silica,
The (D) silica does not contain silica having a particle size of more than 300 nm,
a ratio of the number of epoxy groups in the epoxy resin (C) contained in the curable resin composition to the number of carboxyl groups in the carboxyl group-containing resin (A) is 1.9 to 2.9,
The (A) carboxyl group-containing resin is
A carboxyl group-containing resin obtained by reacting a reaction product obtained by reacting a compound having a plurality of phenolic hydroxyl groups in one molecule with an alkylene oxide, reacting the reaction product with an unsaturated group-containing monocarboxylic acid, and reacting the resulting reaction product with a polybasic acid anhydride; and
A curable resin composition comprising at least one of carboxyl group-containing resins obtained by reacting a compound having multiple phenolic hydroxyl groups in one molecule with a cyclic carbonate compound, reacting the resulting reaction product with an unsaturated group-containing monocarboxylic acid, and reacting the resulting reaction product with a polybasic acid anhydride . The curable resin composition according to claim 1, characterized in that the content of the (D) silica is 5 to 35 mass % based on the total solid content of the composition. The curable resin composition according to claim 1 or 2, characterized in that the (C) epoxy resin consists solely of an epoxy resin having an epoxy equivalent of 100 to 250 g/eq. A dry film having a resin layer obtained by applying the curable resin composition according to any one of claims 1 to 3 onto a film and drying it. A cured product obtained by curing the curable resin composition according to any one of claims 1 to 3 or the resin layer of the dry film according to claim 4. An electronic component comprising the cured product according to claim 5.