JP2008257044A - Solder resist composition and cured product thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solder resist composition which is excellent in developability, resolution, heat resistance and plating resistance required as a solder resist used for a printed wiring board, a package substrate and a module substrate, which ensures less shrinkage by curing and which can provide a substrate free of warpage; and to provide a cured product of the composition. <P>SOLUTION: The solder resist composition has a crosslink density after curing of 2×10<SP>3</SP>-1.2×10<SP>4</SP>mol/m<SP>3</SP>as calculated according to the expression (1): n=E'min/3ΦRT and has a glass transition temperature of ≥100°C, wherein n represents the crosslink density; E'min represents a minimum value of storage modulus E'; Φ represents a front coefficient of about 1; R represents a gas constant; and T represents absolute temperature of E'min. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a printed wiring board, a solder resist composition useful for manufacturing a module substrate, and a cured product thereof. More specifically, the present invention relates to a solder resist composition that can suppress the occurrence of warpage in a substrate that is becoming thinner while maintaining the performance required as a solder resist and a module substrate resist, and a cured product thereof. It is.

  Due to recent rapid advances in semiconductor components, electronic devices are becoming smaller, lighter, higher performance, and multifunctional, and the printed wiring board is becoming increasingly dense following these trends. Moreover, the base material used for such a printed wiring board, a package board | substrate, and a module board has increased the base material of a thin plate.

  Solder resist compositions that are widely used in general include photosensitive resins, photopolymerization initiators, and diluents obtained by reacting a reaction product of a novolak type epoxy compound and an unsaturated monocarboxylic acid with a polybasic acid anhydride. And a photocurable and thermosetting liquid resist ink composition comprising an epoxy compound (see, for example, Patent Document 1). Moreover, as a composition with little curing shrinkage, for example, a terminal isocyanate compound as a reaction product of a compound having at least one carboxyl group and two hydroxyl groups in one molecule, a diol compound, and a polyisocyanate compound, A photosensitive resin composition obtained by reacting a compound having a polymerizable unsaturated group, a carboxyl group and at least one hydroxyl group in one molecule has been proposed (see, for example, Patent Document 2).

  However, such a photosensitive resin composition with little curing shrinkage has a problem that it lacks the heat resistance necessary as a solder resist.

Recently, there is an increasing demand for a black or white solder resist composition for reasons such as making it difficult to see the circuit of the substrate or increasing the reflectance. However, since black or white has poor light transmission, it is necessary to increase the amount of light for exposure in such a composition, and the crosslinking of the coating surface layer is excessively cross-linked compared to the deep part, making it difficult to suppress warpage. Met.
JP-A-1-141904 (Claims) JP 2003-192760 A (Claims)

  The present invention was developed in view of the problems of the background art, and the purpose thereof is developability, resolution, and heat resistance required as a solder resist for use in printed wiring boards, package substrates, and module substrates. An object of the present invention is to provide a solder resist composition that is excellent in plating resistance and that can provide a substrate with little curing shrinkage and no warpage, and a cured product thereof.

  As a result of intensive studies, the present inventors have found that the glass transition temperature (Tg) after curing of the solder resist composition and the crosslinking density are technically closely related in order to provide a substrate with less curing shrinkage and less warpage. As a result, the present invention has been completed.

That is, as one embodiment of the present invention, the crosslink density after curing calculated by the formula (1) is 2 × 10 ^{3 to} 1.2 × 10 ⁴ mol / m ³ and the glass transition temperature (Tg) is 100. A solder resist composition that is at or above ° C is provided.

n = E'min / 3ΦRT (1)
In the formula, n represents the crosslink density, E′min represents the minimum value of the storage elastic modulus E ′, Φ represents the front coefficient≈1, R represents the gas constant, and T represents the absolute temperature of E′min.

  As another embodiment, (A-1) one epoxy compound (a) having two or more epoxy groups in one molecule and one or more alcoholic hydroxyl groups and one epoxy group in one molecule are reacted. A carboxyl group-containing photosensitive resin obtained by reacting a compound (b) having a reactive group with an unsaturated monocarboxylic acid (c) and reacting the resulting reaction product with a polybasic acid anhydride (d). (A-2) a photosensitive resin obtained by reacting a polybasic acid anhydride with a hydroxyl group of an esterified product of a novolak-type epoxy compound and an unsaturated monocarboxylic acid, (B) a photopolymerization initiator, (C) dilution There is provided a solder resist composition containing an agent and (D) a polyfunctional epoxy compound having at least two epoxy groups in one molecule.

  Furthermore, the soldering resist composition containing a white or black coloring agent in addition to the said composition is provided.

As another aspect of the present invention, the crosslinking density calculated by the above formula (1) is 2 × 10 ^{3 to} 1.2 × 10 ⁴ mol / m ³ and the glass transition temperature is 100 ° C. or higher. A solder resist layer comprising a cured product is provided.

  Furthermore, the printed wiring board which has the said soldering resist layer as another aspect is provided.

  The solder resist composition according to the present invention is excellent as developability, resolution, heat resistance, plating resistance, and less curing shrinkage. Therefore, it is used as a solder resist used for printed wiring boards and module substrates that are becoming thinner. Thus, a substrate without warping can be provided.

In order to obtain a solder resist layer having excellent heat resistance and low warpage, the present inventors have completed the cross-linking density after curing and the glass transition temperature (Tg) based on the knowledge that they have a technically close relationship. It is a thing. In other words, the solder resist composition having a crosslink density after curing of 2 × 10 ^{3 to} 1.2 × 10 ⁴ mol / m ³ and a glass transition temperature (Tg) of 100 ° C. or higher has excellent heat resistance and It has been found that it is effective for obtaining a solder resist layer with little warpage.

The solder resist composition having a crosslinking density after curing of 2 × 10 ^{3 to} 1.2 × 10 ⁴ mol / m ³ and a glass transition temperature (Tg) of 100 ° C. or higher is not particularly limited. As a carboxylic acid-containing resin, a carboxyl group-containing photosensitive resin (A-1) that is inferior in photocurability but less warped, has excellent heat resistance and PCT resistance, and heat resistance that is excellent in photocurability but has a large amount of warpage It has been found that it is particularly effective to use a carboxyl group-containing photosensitive resin (A-2) having excellent properties in order to solve the above problems. In the case of a white or black solder resist, it is necessary to increase the exposure amount in order to obtain a resolution as described above, and the combined use of this resin is particularly effective.

  Below, each component of the soldering resist composition of this invention is demonstrated in detail.

  The carboxyl group-containing photosensitive resin (A-1) reacts with an epoxy compound (a) having two or more epoxy groups in one molecule, and one or more alcoholic hydroxyl groups and epoxy groups in one molecule. Carboxylic group-containing compound obtained by reacting compound (b) having one reactive group with unsaturated monocarboxylic acid (c) and reacting the resulting reaction product with polybasic acid anhydride (d) It is a photosensitive resin.

  Examples of the epoxy compound (a) having two or more epoxy groups in one molecule include known and commonly used polyfunctional epoxy compounds such as bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, and biphenyl type epoxy. Resin, bixylenol type epoxy resin, trishydroxyphenylmethane type epoxy resin, tetraphenylethane type epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin, bisphenol A novolak type epoxy resin, glycidyl (meth) acrylate Polymerized resin and the like can be mentioned. Among these, from the viewpoint of heat resistance and photosensitivity of the obtained resin, it is preferable to use a phenol novolac type epoxy resin or a cresol novolac type epoxy resin, particularly a cresol novolak type epoxy resin having a softening point of 50 ° C. or more. .

  As the compound (b) having one reactive group that reacts with one or more alcoholic hydroxyl groups and an epoxy group in one molecule, which is a feature of the carboxyl group-containing photosensitive resin (A-1) of the present invention, for example, Hydroxy-containing monocarboxylic acids such as glycolic acid, dimethylolacetic acid, dimethylolpropionic acid, dimethylolbutanoic acid, dimethylolvaleric acid, dimethylolcaproic acid; dialkanolamines such as diethanolamine and diisopropanolamine; hydroxymethyl-di -T-butylphenol, p-hydroxyphenethyl alcohol, p-hydroxyphenyl-3-propanol, p-hydroxyphenyl-4-butanol, hydroxyethylcresol, 2,6-dimethyl-4-hydroxymethylphenol, 2,4-dihydroxy Methyl Bis (hydroxyalkyl) phenols such as 2-cyclohexylphenol, trimethylolphenol, 3,5-dimethyl-2,4,6-trihydroxymethylphenol, bis (hydroxymethyl) phenol, bis (hydroxymethyl) cresol be able to. Particularly preferred are dimethylolpropionic acid, dimethylolbutanoic acid, and p-hydroxyphenethyl alcohol.

  Since such a compound has a primary hydroxyl group, the polybasic acid anhydride (d) to be added thereafter is higher in temperature than the secondary hydroxyl group obtained by the reaction of an epoxy group and an unsaturated monocarboxylic acid. It becomes difficult to come off even under high humidity.

  As unsaturated monocarboxylic acid (c) used for the synthesis | combination of the carboxyl group-containing photosensitive resin (A-1) of this invention, acrylic acid, methacrylic acid, crotonic acid, vinyl acetic acid, or 2-hydroxyethyl ( For hydroxyl group-containing (meth) acrylate compounds such as (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, trimethylolpropane di (meth) acrylate and pentaerythritol tri (meth) acrylate And a compound to which a dibasic acid anhydride is added. Among these, acrylic acid or methacrylic acid is preferable from the viewpoint of reactivity and the like. These unsaturated monocarboxylic acids can be used alone or in combination of two or more.

  The total amount of the compound (b) having one reactive group that reacts with one or more alcoholic hydroxyl groups and an epoxy group in one molecule and the unsaturated monocarboxylic acid (c) is two or more in one molecule. Preferably it is 0.8-1.3 equivalent with respect to 1 equivalent of epoxy groups of the epoxy compound (a) which has an epoxy group, More preferably, it is the range used as 0.9-1.1 equivalent. When the amount is less than the above range, it is not preferable because it leads to an increase in storage stability and molecular weight such as reaction with a free carboxyl group derived from a polybasic acid anhydride to be added thereafter. On the other hand, when the above range is exceeded, the odor becomes strong and the coating film properties deteriorate, which is not preferable.

  The ratio of the compound (b) having one reactive group that reacts with one or more alcoholic hydroxyl groups and an epoxy group in one molecule and the unsaturated monocarboxylic acid (c) is as follows: (b) :( The range in which c) is 0.05: 0.95 to 0.5: 0.5 is preferred. When the proportion of the component (b) is less than the above range, the polybasic acid anhydride (d) described later is added to the secondary hydroxyl group obtained by the reaction of the epoxy group and the component (c). This is not preferable because the stability under humidity decreases. On the other hand, when the proportion of the component (b) is more than the above range, the amount of photosensitive unsaturated groups introduced is decreased, and it becomes difficult to obtain development resistance, which is not preferable.

  As the polybasic acid anhydride (d) used for the synthesis of the carboxyl group-containing photosensitive resin (A-1) of the present invention, phthalic anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, hexahydrophthalic anhydride, Methylhexahydrophthalic anhydride, succinic anhydride, maleic anhydride, itaconic anhydride, nadic anhydride, octenyl succinic anhydride, pentadodecenyl succinic anhydride, 3,6-endomethylenetetrahydrophthalic anhydride, methylendomethylenetetrahydrophthalic anhydride Dibasic acid or tribasic acid anhydride such as acid, tetrabromophthalic anhydride, trimellitic anhydride, or biphenyltetracarboxylic dianhydride, diphenyl ether tetracarboxylic dianhydride, butanetetracarboxylic dianhydride, cyclo Pentanetetracarboxylic dianhydride , Pyromellitic acid anhydride, aliphatic or aromatic tetracarboxylic acid dianhydride such as benzophenone tetracarboxylic acid dianhydride and the like, can be used one or two or more of these. Among these, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, hexahydrophthalic anhydride, methylhexahydrophthalic anhydride, and succinic anhydride are preferable from the viewpoints of developability and coating properties of the cured product.

  The addition amount of these polybasic acid anhydrides (d) is such that the acid value of the carboxyl group-containing photosensitive resin (A) used in the present invention is preferably in the range of 30 to 120 mgKOH / g, more preferably 40 to 100 mgKOH. / G. When the polybasic acid anhydride (d) is added so that the acid value is less than the above range, the developability with a dilute aqueous alkali solution or the heat resistance decreases, which is not preferable. On the other hand, when the polybasic acid anhydride (d) is added so as to be higher than the above range, the development resistance is lowered, the electrical insulation property, the electroless plating resistance and the like are lowered, and also by thermosetting. Since the generated stress increases, it is not preferable.

Next, (A-2) Photosensitive resin will be described.
Photosensitive resin (A-2) is a photosensitive resin obtained by reacting a polybasic acid anhydride (d) with a hydroxyl group of an esterified product of a novolak epoxy compound (e) and an unsaturated monocarboxylic acid (c). This will be described in more detail. (E) Esterification reaction (total esterification or partial esterification, preferably total ester) of epoxy group of novolak type epoxy compound and (c) carboxyl group of unsaturated monocarboxylic acid And (d) a saturated or unsaturated polybasic acid anhydride is further reacted with the generated hydroxyl group.

  Examples of the novolak type epoxy compound (e) include novolaks obtained by reacting phenols such as phenol, cresol, halogenated phenol, alkylphenol, bisphenol A and formaldehyde in the presence of an acidic catalyst, epichlorohydrin, methyl epichlorohydrin, etc. And those obtained by reacting the epihalohydrin. Commercially available products include YDCN-701, YDCN-704, YDPN-638, YDPN-602 manufactured by Tohto Kasei Co., Ltd .; DEN-431, DEN-439 manufactured by Dow Chemical Company; EPN- manufactured by Ciba Specialty Chemicals Company 1138, EPN-1235, EPN-1299; Dainippon Ink & Chemicals, Inc. N-730, N-770, N-865, N-665, N-673, N-695, VH-4150, VH-4240 , VH-4440; Nippon Kayaku Co., Ltd. EOCN-120, EOCN-104, BRRN-1020; Asahi Kasei Kogyo Co., Ltd. ECN-265, ECN-293, ECN-285, ECN-299, etc. .

  Next, as the unsaturated monocarboxylic acid (b) and the saturated or unsaturated polybasic acid anhydride (c) used for the synthesis of the photosensitive resin (A-2), the photosensitive resin (A-1) is used. It is the same as that illustrated in.

  The esterification of the epoxy group with the epoxy compound and the unsaturated monocarboxylic acid is preferably an epoxy group equivalent number / carboxyl group equivalent number of 0.8 to 1.3, more preferably 0.9 to 1.1. is there.

  For example, the novolac type epoxy compound is dissolved in an organic solvent such as cellosolve acetate, carbitol acetate, methyl ethyl ketone and the like, and a thermal polymerization inhibitor such as hydroquinone, catechol, pyrogallol and the like, and tertiary amines such as benzyldimethylamine and triethylamine as catalysts. A quaternary ammonium salt such as benzyltrimethylammonium chloride or benzyltriethylammonium bromide is added, and the unsaturated monocarboxylic acid is mixed and reacted at 70 to 140 ° C. with heating and stirring.

  Next, the secondary hydroxyl group produced by the esterification reaction of the novolak type epoxy compound and the unsaturated monocarboxylic acid and the polybasic acid anhydride are reacted at 70 to 120 ° C. with heating and stirring by a conventional method. Obtained. The ratio of the novolac epoxy compound to the unsaturated monocarboxylic acid is preferably 0.1 or more with respect to the number of equivalents of secondary hydroxyl groups, and the acid value range of the resulting resin is preferably 30 to 150 mgKOH. / G, more preferably 40 to 100 mg KOH / g.

  The blending ratio of the two photosensitive resin components (A-1) and (A-2) is a mass ratio, preferably 90:10 to 10:90, more preferably 85:15 to 15:85, The total blending ratio of the photosensitive resin components (A-1) and (A-2) with respect to the total mass of the composition is preferably 10 to 50%, more preferably 15 to 45%.

By the way, in solving the above-mentioned problems, the inventors found that the glass transition temperature (Tg) after curing of the solder resist composition of the present invention and the crosslinking density are closely related. Street. In particular, the glass transition temperature (Tg) in the solder resist composition of the present invention is preferably 100 ° C. or higher, more preferably 100 ° C. to 140 ° C. from the viewpoints of substrate warpage suppression, heat resistance, resolution, and the like. The crosslink density is preferably 2 × 10 ^{3 to} 1.2 × 10 ⁴ mol / m ³ , more preferably 5 × 10 ^{3 to} 1.2 × 10 ⁴ mol / m ³ .

  Accordingly, the blending ratio of the two photosensitive resin components (A-1) and (A-2), the blending ratios of the components (B) to (E) described later, and other optional components are described in this specification. It is preferable to adjust so that the glass transition temperature and the crosslinking density are within the above-mentioned ranges.

In the present invention, the crosslinking density (n) and the glass transition temperature (Tg) are determined by the dynamic viscoelasticity test method and calculation formula for thermosetting paints described in JIS K7244-4 described in the examples given later. . That is, the glass transition temperature (Tg) is calculated from E ′ (storage elastic modulus) and E ″ (loss elastic modulus) based on the dynamic viscoelasticity test result obtained according to the test method described in JIS K7244-4:
Tanδ = E "/ E '
The glass transition temperature (Tg) is the temperature at which the value of Tan δ (loss tangent) determined in accordance with the above is the maximum value.

  Further, the crosslinking density (n) is obtained from E ′ (storage elastic modulus) according to the formula (1).

n = ρ / Mc = E′min / 3ΦRT (1)
In Equation (1), E′min represents the minimum value of the storage elastic modulus E ′, Φ represents the front coefficient≈1, ρ represents the sample density, R represents the gas constant, and T represents E′min. The absolute temperature is expressed by Mc and the molecular weight between crosslinks.

Next, (B) the photopolymerization initiator will be described.
Examples of the photopolymerization initiator (B) include acetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, p-dimethylaminopropiophenone, dichloroacetophenone, trichloroacetophenone, p-tert-butyltrichloroacetophenone, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholino-propan-1-one, 2-benzyl-2-dimethylamino-1 Acetophenones such as-(4-morpholinophenyl) -butanone-1, N, N-dimethylaminoacetophenone; benzophenone, methylbenzophenone, 2-chlorobenzophenone, 4,4'-dichlorobenzophenone, 4,4'-bisdimene Benzophenones such as ruaminobenzophenone, 4,4'-bisdiethylaminobenzophenone, Michler's ketone, 4-benzoyl-4'-methyldiphenyl sulfide; benzyl; benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, etc. Benzoin ethers; ketals such as acetophenone dimethyl ketal and benzyl dimethyl ketal; thioxanthones such as thioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2,4-diisopropylthioxanthone; 2 -Methylanthraquinone, 2-ethylanthraquinone, 2-tert-butylanthraquinone, 1-chloroanthraquino Anthraquinones such as 2-aminoanthraquinone and 2,3-diphenylanthraquinone; Organic peroxides such as benzoyl peroxide and cumene peroxide; 2,4,5-triarylimidazole dimer, riboflavin tetrabutyrate, 2 -Thiol compounds such as mercaptobenzimidazole, 2-mercaptobenzoxazole, 2-mercaptobenzothiazole; 2,4,6-tris-s-triazine, 2,2,2-tribromoethanol, tribromomethylphenylsulfone, etc. Organic halogen compounds; 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide) and the like. These compounds can be used alone or in combination of two or more.

  Further, the photopolymerization initiator (B) includes N, N-dimethylaminobenzoic acid ethyl ester, N, N-dimethylaminobenzoic acid isoamyl ester, pentyl-4-dimethylaminobenzoate, triethylamine, triethanolamine and the like. Secondary amines, titanocenes such as bis (η5-cyclopentadienyl) -bis (2,6-difluoro-3- (1H-pyrrol-1-yl) phenyl) titanium, 2- (acetyloxyiminomethyl) thio Xanthen-9-one, 1,2-octanedione, 1- [4- (phenylthio)-, 2- (O-benzoyloxime)], ethanone, 1- [9-ethyl-6- (2-methylbenzoyl) Photosensitizers such as oxime esters such as -9H-carbazol-3-yl]-, 1- (O-acetyloxime) It can be used in combination with one or two or more.

  A preferable combination of the photopolymerization initiator (B) is 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone-1 (for example, Irgacure 369 manufactured by Ciba Specialty Chemicals): Irgacure is a registered trademark) and bis (η5-cyclopentadienyl) -bis (2,6-difluoro-3- (1H-pyrrol-1-yl) phenyl) titanium (for example, manufactured by Ciba Specialty Chemicals) , Irgacure 784), 2,4,6-trimethylbenzoyldiphenylphosphine oxide (for example, Lucylin TPO manufactured by BASF) and 2- (acetyloxyiminomethyl) thioxanthen-9-one (for example, manufactured by Ciba Specialty Chemicals) CGI-325) or bis (2,4,6-trimethylbenzene) Benzoyl) - phenyl phosphine oxide (e.g., Ciba Specialty Chemicals Inc., a combination of Irgacure 819), and the like.

  Moreover, the suitable range of the usage-amount of the above photoinitiators (B) is carboxylic acid containing photosensitive resin (A) (carboxyl group containing photosensitive resin (A-1) and photosensitive resin (A-). The total amount of 2) is preferably 5 to 30 parts by mass, more preferably 5 to 25 parts by mass with respect to 100 parts by mass. When the mixture ratio of a photoinitiator is less than the said range, the photocurability of the composition obtained will worsen. On the other hand, when the amount is larger than the above range, the properties of the resulting cured coating film are deteriorated, and the storage stability of the composition is deteriorated.

  Next, (C) the diluent will be described. As the diluent (C), an organic solvent and / or a photopolymerizable monomer can be used.

  Examples of organic solvents include ketones such as methyl ethyl ketone and cyclohexanone; aromatic hydrocarbons such as toluene, xylene, and tetramethylbenzene; cellosolve, methyl cellosolve, butyl cellosolve, carbitol, methyl carbitol, butyl carbitol, propylene glycol monomethyl ether , Glycol ethers such as dipropylene glycol monomethyl ether, dipropylene glycol diethyl ether, triethylene glycol monoethyl ether; ethyl acetate, butyl acetate, cellosolve acetate, butyl cellosolve acetate, carbitol acetate, butyl carbitol acetate, propylene glycol monomethyl ether Acetates such as acetate and dipropylene glycol monomethyl ether acetate Ethanol, propanol, ethylene glycol, alcohols such as propylene glycol; octane, aliphatic hydrocarbons decane; petroleum ether, petroleum naphtha, hydrogenated petroleum naphtha, and petroleum solvents such as solvent naphtha. These organic solvents can be used alone or in combination of two or more.

  The purpose of using the organic solvent is to form the film by dissolving the carboxyl group-containing photosensitive resin (A-1) and the photosensitive resin (A-2), diluting them, applying them as liquids, and then temporarily drying them. This is to allow contact exposure.

  The usage-amount of an organic solvent is not limited to a specific ratio, It can set suitably according to the coating method etc. to select.

  On the other hand, representative photopolymerizable monomers include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, N-vinylpyrrolidone, acryloylmorpholine, methoxytetraethylene glycol (meth) acrylate, Methoxypolyethylene glycol (meth) acrylate, polyethylene glycol di (meth) acrylate, N, N-dimethyl (meth) acrylamide, N-methylol (meth) acrylamide, N, N-dimethylaminopropyl (meth) acrylamide, N, N- Dimethylaminoethyl (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylate, melamine (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (me ) Acrylate, propylene glycol di (meth) acrylate, dipropylene glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, phenoxyethyl (meth) acrylate, tetrahydrofurfuryl (meth) Acrylate, cyclohexyl (meth) acrylate, glycerin diglycidyl ether di (meth) acrylate, glycerin triglycidyl ether tri (meth) acrylate, isobornyl (meth) acrylate, cyclopentadiene mono- or di- (meth) acrylate; hexanediol, tri Methylolpropane, pentaerythritol, ditrimethylolpropane, dipentaerythritol, tris-hydroxyethyl alcohol Polyhydric (meth) acrylates of polyhydric alcohols such as cyanurate or polyhydric (meth) acrylates of ethylene oxide or propylene oxide adducts of these polyhydric alcohols; mono- of polybasic acids and hydroxyalkyl (meth) acrylates , Di-, tri- or higher polyesters. These photopolymerizable monomers can be used alone or in combination of two or more.

  The purpose of use of the photopolymerizable monomer is to dilute the carboxyl group-containing photosensitive resin (A-1) and the photosensitive resin (A-2) to make it easy to apply and to provide photopolymerization. is there.

  A suitable use amount of the photopolymerizable monomer is suitably in the range of 5 to 40 parts by mass per 100 parts by mass of the total amount of the carboxyl group-containing photosensitive resin (A-1) and the photosensitive resin (A-2). . When the amount of the photopolymerizable monomer used is less than the above range, the effect of imparting photocurability is not sufficient. On the other hand, when the amount exceeds the above range, the touch drying property of the coating film is lowered, which is not preferable.

  As the polyfunctional epoxy compound (D) having at least two epoxy groups in one molecule used in the present invention, for example, EBPS-200 manufactured by Nippon Kayaku Co., Ltd., EPX-30 manufactured by Asahi Denka Kogyo Co., Ltd., Bisphenol S type epoxy resins such as Epiklon EXA-1514 (Epiclon is a registered trademark) manufactured by Dainippon Ink and Chemicals, Inc .; Diglycidyl phthalate resins such as Blemmer DGT (Blenmer is a registered trademark) manufactured by Nippon Oil &Fats; Nissan Chemical Heterocyclic epoxy resins such as TEPIC (registered trademark) manufactured by Ciba Specialty Chemicals Co., Ltd., and xylenol type such as YX-4000 manufactured by Yuka Shell Epoxy Co., Ltd. Epoxy resin; biphenol type epoxy tree such as YL-6056 manufactured by Yuka Shell Epoxy Co., Ltd. An epoxy resin that is sparingly soluble in diluents such as tetraglycidylxylenoylethane resin such as ZX-1063 manufactured by Tohto Kasei Co., Ltd., and Epicoat-1009 and -1031 manufactured by Yuka Shell Epoxy Co., Ltd. (Epicoat is a registered trademark) ), Dainippon Ink & Chemicals, Inc. Epicron N-3050, N-7050, N-9050, Asahi Kasei Kogyo Co., Ltd. AER-664, AER-667, AER-669, Toto Kasei Co., Ltd. YD- 012, YD-014, YD-017, YD-020, YD-002, XAC-5005 from Ciba Specialty Chemicals, GT-7004, 6484T, 6099, DER-642U, DER-673MF from Dow Chemical Bisphenol A type epoxy resins such as EP-5400 and EP-5900 manufactured by Asahi Denka Kogyo Co., Ltd .; Hydrogenated bisphenol A type epoxy resins such as ST-2004 and ST-2007 manufactured by Kasei Co., Ltd .; Bisphenol F types such as YDF-2004 and YDF-2007 manufactured by Tohto Kasei Co., Ltd. and GK-5079L manufactured by Nippon Steel Chemical Co., Ltd. Epoxy resin: SR-BBS, SR-TBA-400 manufactured by Sakamoto Yakuhin Kogyo Co., Ltd., EP-62, EP-66 manufactured by Asahi Denka Kogyo Co., Ltd., AER-755, AER-765 manufactured by Asahi Kasei Kogyo Co., Ltd., Toto Brominated bisphenol A type epoxy resins such as YDB-600 and YDB-715 manufactured by Kasei Co., Ltd .; EPPN-201, EOCN-103, EOCN-1020, EOCN-1025, BREN manufactured by Nippon Kayaku Co., Ltd., Asahi Kasei Kogyo ( Co., Ltd. ECN-278, ECN-292, ECN-299, Ciba Specialty Chemicals ECN-1273, E CN-1299, YDCN-220L, YDCN-220HH, YDCN-702, YDCN-704, YDPN-601, YDPN-602, manufactured by Daito Ink Chemical Co., Ltd., Epicron N-673, N- Novolak type epoxy resins such as 680, N-695, N-770, and N-775; EPX-8001, EPX-8002, EPPX-8060, EPPX-8061 manufactured by Asahi Denka Kogyo Co., Ltd., Dainippon Ink & Chemicals, Inc. ) Epoxylon N-880 and other bisphenol A novolak type epoxy resins; Asahi Denka Kogyo Co., Ltd. EPX-49-60, EPX-49-30 and other chelate type epoxy resins; Toto Kasei Co., Ltd. YDG-414 Glyoxal type epoxy resin, etc .; YH-1402, ST-110 manufactured by Toto Kasei Co., Ltd. Amino group-containing epoxy resins such as YL-931 and YL-933 manufactured by Epoxy Corporation; Epicron TSR-601 manufactured by Dainippon Ink & Chemicals, Inc. EPX-84-2 and EPX-4061 manufactured by Asahi Denka Kogyo Co., Ltd. Rubber-modified epoxy resins such as Sanyo Kokusaku Pulp Co., Ltd. DCE-400 and other dicyclopentadiene phenolic epoxy resins; Asahi Denka Kogyo Co., Ltd. X-1359 and other silicone-modified epoxy resins; Daicel Chemical Industries, Ltd. Examples include epoxy resins that are soluble in diluents such as ε-caprolactone-modified epoxy resins such as Plaxel G-402 and G-710. These epoxy resins can be used singly or in combination of two or more, but in particular, a finely particulate epoxy resin hardly soluble in a diluent, or a combination of a hardly soluble epoxy resin and a soluble epoxy resin. Is preferred.

  The blending ratio of the polyfunctional epoxy compound (D) as the thermosetting component is 10 to 70 masses per mass part of the total amount of the carboxyl group-containing photosensitive resin (A-1) and the photosensitive resin (A-2). The range of parts is preferred, more preferably 15 to 50 parts by weight.

  Further, as the white or black colorant (E) used in the present invention, known and commonly used colorants can be used. Examples include compounds classified as Pigments in the Color Index (CI; published by The Society of Dyers and Colourists), specifically those with the following Color Index (CI) numbers: it can.

  Examples of the white colorant include zinc oxide shown in CI Pigment White 4, titanium oxide shown in CI Pigment White 6, and zinc sulfide shown in CI Pigment White 7, but particularly from the viewpoint of coloring power and non-toxicity. Titanium oxide is preferable, for example, TR-600, TR-700, TR-750, TR-840 manufactured by Fuji Titanium Industry Co., Ltd., R-550, R-580, R-630, R, Ishihara Sangyo Co., Ltd. -820, CR-50, CR-60, CR-90, RU-type titanium oxide such as KR-270, KR-310, KR-380 manufactured by Titanium Industry Co., Ltd., TA-100 manufactured by Fuji Titanium Industry Co., Ltd. TA-200, TA-300, TA-500, A100, A220 manufactured by Ishihara Sangyo Co., Ltd., KA-15, KA-20, KA-35, KA-9 manufactured by Titanium Industry Co., Ltd. Anatase type titanium oxide and the like. The blending ratio is not particularly limited, but it is preferably 0.1 to 50% by mass, and most preferably 0.5 to 40% by mass in all components of the resist composition of the present invention excluding the organic solvent. When it is less than 0.1% by mass, it is difficult to obtain a sufficient concentration, and when it is more than 50% by mass, problems such as insufficient strength of the coating film are liable to occur.

  Examples of the black colorant include carbon black pigments indicated by CI pigment black 6, 7, 9 and 18; graphite pigments indicated by CI pigment black 8, 10; CI pigment black 11 , 12 and 27 etc .: For example, Toda Kogyo KN-370 iron oxide, Mitsubishi Materials Corporation 13M titanium black, CI pigment black 20 anthraquinone Pigments, cobalt pigments such as CI pigment black 13, 25 and 29, copper oxide pigments such as CI pigment black 15 and 28, manganese pigments such as CI pigment black 14 and 26, etc. Pigment, antimony oxide pigment represented by CI pigment black 23, CI pigment Click 30 nickel oxide pigments represented by like, C.I. Perylene pigments represented by Pigment Black 31, 32, and molybdenum sulfide and bismuth sulfide can also be exemplified as a preferable pigment. These pigments are used alone or in appropriate combination. Particularly preferred is carbon black, for example, carbon black manufactured by Mitsubishi Chemical Corporation, M-40, M-45, MA-8, MA-100, and perylene pigments are low halogenated among organic pigments. It is effective for. The compounding amount is not particularly limited, but is 0.01 to 20% by mass, more preferably 0.1 to 10% by mass, and most preferably 0.2 to 7% in all components of the resist composition of the present invention excluding the organic solvent. It is preferable that it is contained by mass%. When the amount is less than 0.01% by mass, it is difficult to obtain a sufficient concentration. On the other hand, when it is more than 20% by mass, problems such as insufficient strength of the coating film are likely to occur.

  In the present invention, an epoxy curing catalyst can be used together with the polyfunctional epoxy compound (D).

  Examples of such a curing catalyst include imidazole, 2-methylimidazole, 2-ethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 4-phenylimidazole, 1-cyanoethyl-2-phenylimidazole, Imidazole derivatives such as 1- (2-cyanoethyl) -2-ethyl-4-methylimidazole; dicyandiamide, benzyldimethylamine, 4- (dimethylamino) -N, N-dimethylbenzylamine, 4-methoxy-N, N- Amine compounds such as dimethylbenzylamine, 4-methyl-N, N-dimethylbenzylamine, hydrazine compounds such as adipic hydrazide and sebacic acid hydrazide; phosphorus compounds such as triphenylphosphine, For example, Shikoku 2MZ-A, 2MZ-OK, 2PHZ, 2P4BHZ, 2P4MHZ (all are trade names of imidazole compounds) manufactured by Seiko Kogyo Co., Ltd., U-CAT3503N, U-CAT3502T (all are dimethylamine block isocyanate compounds) Product name), DBU, DBN, U-CATSA102, U-CAT5002 (all are bicyclic amidine compounds and salts thereof), and the like can be used alone or in admixture of two or more. Guanamine, acetoguanamine, benzoguanamine, melamine, 2,4-diamino-6-methacryloyloxyethyl-S-triazine, 2-vinyl-2,4-diamino-S-triazine, 2 S-triazine derivatives such as -vinyl-4,6-diamino-S-triazine / isocyanuric acid adduct, 2,4-diamino-6-methacryloyloxyethyl-S-triazine / isocyanuric acid adduct can also be used, Preferably, a compound that also functions as an adhesion promoter is used in combination with the thermosetting catalyst.

  In addition, the solder resist composition of the present invention can be blended with an inorganic filler for the purpose of further improving properties such as adhesion, mechanical strength, and linear expansion coefficient of the cured product. For example, known and commonly used inorganic fillers such as barium sulfate, barium titanate, silicon oxide powder, finely divided silicon oxide, amorphous silica, talc, clay, magnesium carbonate, calcium carbonate, aluminum oxide, aluminum hydroxide, mica powder, etc. Can be used.

  If necessary, the solder resist composition of the present invention may be a known conventional thermal polymerization inhibitor such as hydroquinone, hydroquinone monomethyl ether, t-butylcatechol, pyrogallol, phenothiazine, or the like, or a known conventional polymer such as finely divided silica, organic bentonite, or montmorillonite. Conventional additives such as thickeners, silicone-based, fluorine-based, polymer-based antifoaming agents and / or leveling agents, imidazole-based, thiazole-based, triazole-based silane coupling agents, etc. Can be blended.

  Furthermore, in the present invention, a colorant such as phthalocyanine blue, phthalocyanine green, iodin green, or disazo yellow can be added as long as the white or black color of the cured product is not impaired.

  The solder resist composition of the present invention is adjusted to a viscosity suitable for the coating method using, for example, the diluent (C), and a dip coating method, a flow coating method, a roll coating method, a bar coater method on a circuit-formed substrate. The tack-free coating film is formed by coating the entire surface by a method such as screen printing or curtain coating, and evaporating and drying (preliminarily drying) the organic solvent contained in the composition at a temperature of about 60 to 100 ° C. it can. A coating film can also be formed by applying the above composition on a carrier film, drying it and winding it as a film on a substrate. Then, the contact type (or non-contact type) is selectively exposed with active energy rays through a photomask having a pattern formed, and the unexposed portion is developed with a dilute alkaline aqueous solution (for example, 0.3 to 3% sodium carbonate aqueous solution). Thus, a resist pattern is formed.

  Furthermore, for example, a cured coating film excellent in various properties such as heat resistance, chemical resistance, moisture absorption resistance, adhesion, and electrical characteristics is formed by heating to a temperature of about 140 to 180 ° C. and thermosetting. Can do.

  Base materials used for the circuit-formed substrate include paper phenol, paper epoxy, glass cloth epoxy, glass polyimide, glass cloth / non-woven cloth epoxy, glass cloth / paper epoxy, synthetic fiber epoxy, fluorine / polyethylene / PPO・ Copper-clad laminates of all grades (FR-4, etc.) using materials such as copper-clad laminates for high-frequency circuits using cyanate esters, etc., other polyimide films, PET films, glass substrates, ceramic substrates, A wafer board etc. can be mentioned.

  Moreover, as an irradiation light source used for active energy ray irradiation, a low-pressure mercury lamp, a medium-pressure mercury lamp, a high-pressure mercury lamp, an ultrahigh-pressure mercury lamp, a xenon lamp, a metal halide lamp, or the like is appropriate. In addition, laser beams and the like can also be used as active energy rays.

  The developing method can be a dipping method, a shower method, a spray method, a brush method or the like, and as a developer, potassium hydroxide, sodium hydroxide, sodium carbonate, potassium carbonate, sodium phosphate, sodium silicate, A dilute alkaline aqueous solution such as ammonia or amines can be used.

  EXAMPLES Hereinafter, the present invention will be described in detail with reference to examples and comparative examples, but the present invention is not limited to the following examples. In the following description, “part” means “part by mass” unless otherwise specified.

<Synthesis of photosensitive resin>
The photosensitive resin (A-1) of the present invention was prepared according to Synthesis Examples 1 and 2 below, and the carboxyl group-containing photosensitive resin (A-2) was prepared according to Synthesis Example 3 below.

(Synthesis Example 1)
Cresol novolac type epoxy resin (manufactured by Nippon Kayaku Co., Ltd., EOCN-104S, softening point 92 ° C., epoxy equivalent 220) 220 parts, dimethylolpropionic acid 13.4 parts, acrylic acid 65 parts, methylhydroquinone 0.46 parts Then, 113 parts of carbitol acetate and 48.5 parts of solvent naphtha were charged, heated to 90 ° C. and stirred to dissolve the reaction mixture. The reaction solution was then cooled to 60 ° C., charged with 1.4 parts of triphenylphosphine, heated to 100 ° C., and reacted for about 32 hours to obtain a reaction product having an acid value of 0.5 mg KOH / g. Next, 36.5 parts of tetrahydrophthalic anhydride, 13.8 parts of carbitol acetate and 6.0 parts of solvent naphtha are added to this, heated to 95 ° C., reacted for about 6 hours, cooled, and cooled to solid acid. A carboxyl group-containing photosensitive resin having a value of 40 mgKOH / g and a nonvolatile content of 65% was obtained. Hereinafter, this reaction solution is referred to as varnish (A-1a).

(Synthesis Example 2)
A cresol novolac type epoxy resin (manufactured by Nippon Kayaku Co., Ltd., EOCN-104S, softening point 92 ° C., epoxy equivalent 220) 220 parts (1 equivalent) was placed in a four-necked flask equipped with a stirrer and a reflux condenser. 218 parts of tall acetate was added and dissolved by heating. Next, 0.46 parts of methylhydroquinone as a polymerization inhibitor and 1.38 parts of triphenylphosphine as a reaction catalyst were added. This mixture was heated to 95 to 105 ° C., 50.4 parts (0.7 equivalents) of acrylic acid and 41.5 parts (0.3 equivalents) of p-hydroxyphenethyl alcohol were gradually added dropwise and reacted for 16 hours. . This reaction product (hydroxyl group: 1.3 equivalents) is cooled to 80 to 90 ° C., 91.2 parts (0.6 equivalents) of tetrahydrophthalic anhydride is added and reacted for 8 hours. After cooling, the reaction solution ( The varnish (referred to as A-1b) was taken out.

  The carboxyl group-containing photosensitive resin thus obtained had a solid acid value of 83 mgKOH / g and a nonvolatile content of 65%.

(Synthesis Example 3)
Cresole novolak type epoxy resin (manufactured by Dainippon Ink & Chemicals, Inc., “Epiclon” (registered trademark) N-695, epoxy equivalent: 220) is placed in a four-necked flask equipped with a stirrer and a reflux condenser. Then, 214 parts of carbitol acetate was added and dissolved by heating. Next, 0.46 part of hydroquinone as a polymerization inhibitor and 1.38 parts of triphenylphosphine as a reaction catalyst were added. This mixture was heated to 95 to 105 ° C., and 72 parts of acrylic acid was gradually added dropwise to react for 16 hours. The reaction product was cooled to 80 to 90 ° C., 106 parts of tetrahydrophthalic anhydride was added and reacted for 8 hours. After cooling, the reaction solution (referred to as varnish (A-2)) was taken out. The photosensitive resin thus obtained had a solid acid value of 100 mgKOH / g and a non-volatile content of 65%.

<Examples 1-12 and Comparative Examples 1-8>
Three varnishes (A-1a), varnish (A-1b), and varnish (A-2) obtained in Synthesis Examples 1 to 3 and the components shown in Table 1 in the blending ratio described in the same table The solder resist composition was obtained by kneading with a roll mill.

  About the solder resist composition of Examples 1-12 and Comparative Examples 1-8, performance was evaluated according to the following evaluation criteria. The results are shown in Table 2.

Performance evaluation:
(1) Filler residue, hot fog The solder resist compositions of Examples 1 to 12 and Comparative Examples 1 to 8 were each coated on the entire surface of a copper-clad substrate by screen printing, and heated at 80 ° C. in a hot air circulating drying oven. The film was dried for a while and developed with a 1% by mass Na ₂ CO ₃ aqueous solution having a spray pressure of 0.2 MPa for 1 minute.

○: The coating film is completely removed and there is no residue.

Δ: There is a slight filler residue.

X: There is a residue of the coating film.

(2) Resolution (Black) A circuit pattern board having a line / space of 300/300 and a copper thickness of 50 μm was polished with buffalo, washed with water, dried, and then compared with Examples 1 to 3 and 7 to 9. Each of the solder resist compositions of Examples 1, 2, 5, and 6 was applied by a screen printing method and dried for 30 minutes in a hot air circulation drying oven at 80 ° C. Then, it exposed with the metal halide lamp. As an exposure pattern, a negative film having a line / space of 100/300 was used, and an active energy ray was irradiated so that the exposure amount was 500 mJ / cm ² on the solder resist composition. After exposure, development (30 ° C., spray pressure 0.2 MPa, 1 mass% Na ₂ CO ₃ ) is performed for 60 seconds to remove the unexposed areas, thereby forming a pattern, and then heat curing at 150 ° C. for 60 minutes. By performing the treatment, a cured coating film was obtained. The line width reproducibility of the 100 μm line pattern thus obtained was expressed as undercut / negative dimensions.

(White) A circuit pattern substrate having a line / space of 300/300 and a copper thickness of 50 μm was polished with buffalo, washed with water, and dried, followed by Examples 4-6, 10-12, and Comparative Examples 3, 4, 7 , 8 were applied by a screen printing method and dried in a hot air circulation drying oven at 80 ° C. for 30 minutes. Then, it exposed with the metal halide lamp. As the exposure pattern, a negative film having a line / space of 100/300 was used, and the active energy ray was irradiated so that the exposure amount was 500 mJ / cm ² on the photosensitive resin composition. After exposure, development (30 ° C., spray pressure 0.2 MPa, 1 mass% Na ₂ CO ₃ ) is performed for 60 seconds to remove the unexposed areas, thereby forming a pattern, and then heat curing at 150 ° C. for 60 minutes. By performing the treatment, a cured coating film was obtained. The line width reproducibility of the 100 μm line pattern thus obtained was expressed as halation / negative dimensions.

(3) Heat resistance Each of the solder resist compositions of Examples 1 to 12 and Comparative Examples 1 to 8 was applied on the entire surface of a printed wiring board on which a circuit was formed by screen printing, and then dried in a hot air circulation drying oven for 30 minutes. It was. A negative film on which a solder resist pattern is drawn is applied to these substrates, and the exposure amount is exposed on the photosensitive resin composition under the exposure condition of 500 mJ / cm ² , and the spray pressure is 0.2 MPa and the 1 mass% Na ₂ CO ₃ aqueous solution. And developed for 1 minute to form a solder resist pattern. This substrate was thermally cured at 150 ° C. for 60 minutes to produce an evaluation substrate. A tape peel test was performed to evaluate the swelling, peeling, and discoloration of the resist layer.

○: No change is observed at all.

Δ: There is a slight change such as discoloration.

X: Resist layer swelling and peeling.

(4) Whitening About Examples 1-3, 7-9, Comparative Examples 1, 2, 5, and 6 (only a black resist), the cloudiness of the coating-film surface was confirmed visually after the heat resistance test.

○: No discoloration in the coating film.

Δ: Slightly cloudy discoloration.

X: The whole coating film becomes cloudy.

(5) Warpage Each of the solder resist compositions of Examples 1 to 12 and Comparative Examples 1 to 8 was screen-printed on a base material thickness 0.06 mm BT material etch-out (340 × 340) substrate, about 25 μm (dry) on one side. It is applied and dried for 30 minutes in a hot air circulating drying furnace, and the entire surface is exposed under an exposure condition of 500 mJ / cm ² on the solder resist composition. Then, spray pressure 0.2 MPa, development and 1 minute at 1 wt% _Na 2 CO ₃ aqueous solution, and cured 0.99 ° C. × 60 minutes heat at a hot-air circulating drying oven to prepare a test substrate. After the evaluation substrate is sufficiently cooled, the warp of the manufactured substrate is evaluated. Place the substrate on a flat surface and measure the height of the floating substrate edge.

○: Warpage that can be printed on the screen printing machine with the warping of the evaluation board as it is (floating height less than 20 mm)
(Triangle | delta): The floating height is 20 mm or more, and the end of a board | substrate is match | combined (a board | substrate makes 1 round) or less.

X: The edge of a board | substrate is match | combined. (The circuit board makes one round)
(6) Dynamic viscoelasticity test Test method: Coating film preparation method The solder resist compositions of Examples 1 to 12 and Comparative Examples 1 to 8 above are on the film so as to be 25 to 50 µm (dry) by screen printing. It is dried at 80 ° C. for 30 minutes in a hot air circulating drying oven, and the entire surface is exposed under an exposure condition of 500 mJ / cm ² on the photosensitive resin composition. Then, spray pressure 0.2 MPa, development and 1 minute at 1 wt% _Na 2 CO ₃ aqueous solution, and cured 0.99 ° C. × 60 minutes heat at a hot-air circulating drying oven to prepare a test film. Collect the coating film from the film and set it on the measuring instrument.

Measuring device / Seiko Instruments
Format: DMS6100
Measurement conditions / temperature: 20 to 300 ° C
Temperature increase rate: 5 ° C / min
Frequency: 1, 10Hz
Deformation mode: Pull / Sine wave mode
Measurement film size: 10 mm x 5 mm
A dynamic viscoelasticity test is performed by the test method described in JIS K7244-4 to obtain E ′ (storage elastic modulus) and E ″ (loss elastic modulus). And the glass transition temperature (Tg) are shown in Table 2.

  As is apparent from Table 2, it can be seen that the solder resist composition of the present invention is excellent in performance required as a solder resist while minimizing warping even for thin plates.

Claims (7)

Solder resist composition characterized by having a crosslinking density after curing calculated by the formula (1) of 2 × 10 ^{3 to} 1.2 × 10 ⁴ mol / m ³ and a glass transition temperature of 100 ° C. or higher. object.
n = E'min / 3ΦRT (1)
In the formula, n represents the crosslink density, E′min represents the minimum value of the storage elastic modulus E ′, Φ represents the front coefficient≈1, R represents the gas constant, and T represents the absolute temperature of E′min. (A-1) An epoxy compound (a) having two or more epoxy groups in one molecule, and a compound having one reactive group that reacts with one or more alcoholic hydroxyl groups and an epoxy group in one molecule ( a carboxyl group-containing photosensitive resin obtained by reacting b) with an unsaturated monocarboxylic acid (c) and reacting the resulting reaction product with a polybasic acid anhydride (d),
(A-2) a photosensitive resin obtained by reacting a polybasic acid anhydride (d) with a hydroxyl group of an esterified product of a novolak-type epoxy compound (e) and an unsaturated monocarboxylic acid (c),
(B) a photopolymerization initiator,
(C) a diluent, and (D) a polyfunctional epoxy compound having at least two epoxy groups in one molecule,
The solder resist composition according to claim 1, comprising:   The solder resist composition according to claim 1, further comprising (E) a white or black colorant. (A-1) An epoxy compound (a) having two or more epoxy groups in one molecule, and a compound having one reactive group that reacts with one or more alcoholic hydroxyl groups and an epoxy group in one molecule ( a carboxyl group-containing photosensitive resin obtained by reacting b) with an unsaturated monocarboxylic acid (c) and reacting the resulting reaction product with a polybasic acid anhydride (d),
(A-2) a photosensitive resin obtained by reacting a polybasic acid anhydride (d) with a hydroxyl group of an esterified product of a novolak-type epoxy compound (e) and an unsaturated monocarboxylic acid (c),
(B) a photopolymerization initiator,
(C) Diluent,
(D) A polyfunctional epoxy compound having at least two epoxy groups in one molecule, and (E) a solder resist composition containing a white or black colorant. A solder resist characterized by comprising a cured product having a crosslinking density calculated by the formula (1) of 2 × 10 ^{3 to} 1.2 × 10 ⁴ mol / m ³ and a glass transition temperature of 100 ° C. or higher. layer.
n = E'min / 3ΦRT (1)
In the formula, n represents the crosslink density, E′min represents the minimum value of the storage elastic modulus E ′, Φ represents the front coefficient≈1, R represents the gas constant, and T represents the absolute temperature of E′min. The solder resist layer according to claim 5,
(A-1) An epoxy compound (a) having two or more epoxy groups in one molecule, and a compound having one reactive group that reacts with one or more alcoholic hydroxyl groups and an epoxy group in one molecule ( a carboxyl group-containing photosensitive resin obtained by reacting b) with an unsaturated monocarboxylic acid (c) and reacting the resulting reaction product with a polybasic acid anhydride (d),
(A-2) a photosensitive resin obtained by reacting a polybasic acid anhydride (d) with a hydroxyl group of an esterified product of a novolak-type epoxy compound (e) and an unsaturated monocarboxylic acid (c),
(B) a photopolymerization initiator,
(C) Diluent,
(D) A solder resist layer obtained by curing a solder resist composition containing a polyfunctional epoxy compound having at least two epoxy groups in one molecule, and (E) a white or black colorant. .   A printed wiring board comprising the solder resist layer according to claim 5.