JP6524572B2 - Composition for solder resist and printed wiring board - Google Patents

Description

  The present invention relates to a composition for solder resist used to form a solder resist layer, and a printed wiring board provided with a solder resist layer formed from the composition for solder resist.

  In order to form a solder resist layer in a printed wiring board, a composition containing a photosensitive resin having a radically polymerizable unsaturated group is conventionally used (see Patent Document 1). In such a composition, a photopolymerization initiator is usually blended to impart photocurability. In addition, the composition may need to contain a thixotropic agent such as finely divided silica for the purpose of adjusting the thixotropy and the like.

  In recent years, with the reduction in size and weight of electronic devices, the densification of printed wiring boards has progressed. Along with this, it is necessary to improve the performance of the solder resist layer.

  In particular, with the recent increase in the density of conductor wiring, it is expected that migration in the solder resist layer will be a problem. That is, even if the migration is slight, if the conductor wiring has a high density, a short circuit may occur. Furthermore, the solder resist layer is required to have gold plating resistance.

JP 2008-189928 A

  The present invention has been made in view of the above problems, and is a composition for a solder resist containing a photopolymerization initiator and a thixotropic agent, which is used to form a solder resist layer, and the solder resist layer is used. It is possible to provide a solder resist composition capable of suppressing the occurrence of migration at a high level and further having excellent gold plating resistance, and a printed wiring board provided with a solder resist layer formed from the composition for solder resist. It will be an issue.

A composition for a solder resist according to a first aspect of the present invention comprises a carboxyl group-containing resin (A) having an ethylenically unsaturated group, a photopolymerization initiator (B), and a thixotropy imparting agent (C). A composition for a solder resist comprising:
The photopolymerization initiator (B) contains an acylphosphine oxide photopolymerization initiator and an α-hydroxyacetophenone photopolymerization initiator, and the thixotropic agent (C) contains a swellable layered silicate. It is characterized by

  In the composition for a solder resist according to the second aspect of the present invention, in the first aspect, the carboxyl group-containing resin (A) is an epoxy compound (a1) having two or more epoxy groups in one molecule. An ethylenically unsaturated compound (a2) having a carboxyl group is added to at least one of the epoxy groups, and at least one compound (a3) selected from the group consisting of polyvalent carboxylic acids and their anhydrides Contains a resin having a structure added.

  The composition for a solder resist according to the third aspect of the present invention, in the first or second aspect, further contains an epoxy compound (D) having two or more epoxy groups in one molecule.

  The composition for a solder resist according to a fourth aspect of the present invention further comprises a photopolymerizable compound (E) according to any one of the first to third aspects, and the photopolymerizable compound (E) is And one or more compounds selected from the group consisting of photopolymerizable monomers and photopolymerizable prepolymers.

  A printed wiring board according to a fifth aspect of the present invention includes a solder resist layer formed of the composition for a solder resist according to any one of the first to fourth aspects.

  According to the present invention, when the composition for solder resist contains a photopolymerization initiator and a thixotropic agent, the migration of the solder resist layer formed from the composition for solder resist is significantly suppressed, which is further excellent. Resistance to gold plating.

  The composition for a solder resist according to the present embodiment contains a carboxyl group-containing resin (A) having an ethylenically unsaturated group, a photopolymerization initiator (B), and a thixotropic agent (C). Furthermore, the photopolymerization initiator (B) contains an acylphosphine oxide photopolymerization initiator and an α-hydroxyacetophenone photopolymerization initiator, and the thixotropic agent (C) contains a swellable layered silicate. .

  Swellable layered silicates have a high ability to control thixotropy. In addition, when the composition for solder resist contains the photopolymerization initiator (B) and the thixotropy-imparting agent (C), the photopolymerization initiator (B) is an acylphosphine oxide photopolymerization as in the present embodiment. When the thixotropic agent (C) further contains an initiator and an α-hydroxyacetophenone photopolymerization initiator and the thixotropic agent (C) contains a swellable layered silicate, the migration of the solder resist layer is remarkably suppressed, and the gold plating resistance is excellent. Is obtained. Although the reason is not clear yet, the acylphosphine oxide photopolymerization initiator is highly curable in the deep portion of the coating film, while the α-hydroxyacetophenone photopolymerization initiator is highly curable in the film surface and oxygen at the time of exposure In order to play a role of preventing inhibition, it is considered that a crosslinked structure by photopolymerization is efficiently generated in the entire coating film upon exposure, whereby migration of the solder resist layer is suppressed and excellent gold plating resistance is obtained. In addition, it is thought that the fact that the acyl phosphine oxide type photoinitiator and the α-hydroxylacetophenone type photoinitiator do not contain a metal atom that promotes migration is also contributing to the effect of suppressing migration. In addition, the use of the swellable layered silicate in order to enhance the thixotropy of the composition for solder resist further suppresses migration of the solder resist layer. It is inferred that this is because the solder resist layer contains a swellable layered silicate so that the solder resist layer has a sea-island structure, and as a result, movement of impurity ions in the solder resist layer is suppressed. Ru. Furthermore, the swellable layered silicate has the property of easily incorporating various chemical species into its layer, which is presumed to contribute to the suppression of migration.

  The components of the solder resist composition will be described in detail.

  The carboxyl group-containing resin (A) is not particularly limited as long as it is a resin provided with an ethylenically unsaturated group and a carboxyl group.

The carboxyl group-containing resin (A) is, for example, an ethylenically unsaturated compound (a2) having a carboxyl group in at least one of the epoxy groups in the epoxy compound (a1) having two or more epoxy groups in one molecule. There react further at least one compound (a3) is a resin having a structure added (hereinafter, the first resin (a) hereinafter) is selected from the group consisting of polycarboxylic acids and anhydrides that contain Can.

  The epoxy compound (a1) is, for example, cresol novolac epoxy resin, phenol novolac epoxy resin, bisphenol A epoxy resin, bisphenol F epoxy resin, bisphenol A-novolac epoxy resin, naphthalene epoxy resin, biphenyl epoxy resin, At least one resin selected from the group consisting of biphenyl aralkyl type epoxy resin, triglycidyl isocyanurate, alicyclic epoxy resin, and polymer of ethylenically unsaturated compound (p) including compound (p1) having an epoxy group It can be contained.

  The polymer of the ethylenically unsaturated compound (p) containing the compound (p1) which has an epoxy group is demonstrated.

  The ethylenically unsaturated compound (p) to be provided for the synthesis of the polymer may contain only the compound (p1) having an epoxy group, and the compound (p1) having an epoxy group and the compound having no epoxy group ((1) and p2) may be contained.

  The compound (p1) having an epoxy group can contain a compound selected from suitable polymers and prepolymers. Specifically, the compound (p1) having an epoxy group is epoxycyclohexyl derivatives of acrylic acid, epoxycyclohexyl derivatives of methacrylic acid, alicyclic epoxy derivative of acrylate, alicyclic epoxy derivative of methacrylate, β-methylglycidyl acrylate And one or more compounds selected from the group consisting of β-methyl glycidyl methacrylate. In particular, it is preferable that the compound (p1) having an epoxy group contains glycidyl (meth) acrylate which is widely available and easily available.

  The compound (p2) not having an epoxy group may be a compound copolymerizable with the compound (p1) having an epoxy group. The compound (p2) not having an epoxy group is, for example, 2- (meth) acryloyloxyethyl phthalate, 2- (meth) acryloyloxyethyl-2-hydroxyethyl phthalate, 2- (meth) acryloyloxypropyl phthalate, Benzyl (meth) acrylate, neopentyl glycol benzoate (meth) acrylate, paracumyl phenoxy ethylene glycol (meth) acrylate, EO modified cresol (meth) acrylate, ethoxylated phenyl (meth) acrylate, nonyl phenoxy polyethylene glycol (meth) acrylate Degree of polymerization n = 2 to 17), ECH modified phenoxy (meth) acrylate, phenoxydiethylene glycol (meth) acrylate, phenoxyethyl (meth) acrylate, phenoxyhexaeth Glycol (meth) acrylate, phenoxytetraethylene glycol (meth) acrylate, tribromophenyl (meth) acrylate, EO modified tribromophenyl (meth) acrylate, EO modified bisphenol A di (meth) acrylate, PO modified bisphenol A di ( Meta) acrylate, modified bisphenol A di (meth) acrylate, EO modified bisphenol F di (meth) acrylate, ECH modified phthalic acid di (meth) acrylate, trimethylolpropane benzoate (meth) acrylate, EO modified phthalic acid (meth) acrylate EO, PO modified phthalic acid (meth) acrylate, vinyl carbazole, styrene, N-phenyl maleimide, N-benzyl maleimide, 3-maleimidobenzoic acid N-succinimide , Linear or branched aliphatic or alicyclic (but may have partially unsaturated bonds in the ring) (meth) acrylic acid ester, hydroxyalkyl (meth) acrylate, alkoxyalkyl It can contain one or more compounds selected from the group consisting of meta) acrylates and N-substituted maleimides (e.g. N-cyclohexyl maleimide).

  The compound (p2) not having an epoxy group may further contain a compound having two or more ethylenic unsaturated groups in one molecule. The hardness and the oil property of the solder resist layer can be easily adjusted by using this compound and adjusting the compounding amount thereof. Compounds having two or more ethylenically unsaturated groups in one molecule are, for example, polyethylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, and pentaerythritol tri (meth) It can contain one or more compounds selected from the group consisting of acrylates.

  A polymer is obtained by polymerizing the ethylenically unsaturated compound (p) by a known polymerization method such as, for example, a solution polymerization method or an emulsion polymerization method. Specific examples of the solution polymerization method include a method of heating and stirring the ethylenically unsaturated compound (p) in a suitable organic solvent in the presence of a polymerization initiator under a nitrogen atmosphere, and an azeotropic polymerization method.

  Organic solvents used for the polymerization of the ethylenically unsaturated compound (p) are, for example, ketones such as methyl ethyl ketone and cyclohexanone, and aromatic hydrocarbons such as toluene and xylene, and ethyl acetate, butyl acetate, cellosolve acetate It may contain one or more compounds selected from the group consisting of acetic acid esters such as butyl cellosolve acetate, butyl carbitol acetate and propylene glycol monomethyl ether acetate, and dialkyl glycol ethers.

  The polymerization initiator used for the polymerization of the ethylenically unsaturated compound (p) is, for example, hydroperoxides such as diisopropylbenzene hydroperoxide, dicumyl peroxide, 2,5-dimethyl-2,5-di -Dialkyl peroxides such as-(t-butylperoxy) -hexane, diacyl peroxides such as isobutyryl peroxide, ketone peroxides such as methyl ethyl ketone peroxide, alkyl peresters such as t-butylperoxy bivalate And one or more compounds selected from the group consisting of peroxydicarbonates such as diisopropyl peroxydicarbonate, azo compounds such as azobisisobutyronitrile, and initiators of a redox system.

  The ethylenically unsaturated compound (a2) used for the synthesis of the first resin (a) can contain a compound selected from the group consisting of suitable polymers and prepolymers. The ethylenically unsaturated compound (a2) can contain a compound having only one ethylenically unsaturated group. The compound having only one ethylenically unsaturated group is, for example, acrylic acid, methacrylic acid, crotonic acid, cinnamic acid, 2-acryloyloxyethyl succinic acid, 2-methacryloyloxyethyl succinic acid, 2-acryloyl oxyethyl phthalic acid, 2 -Methacryloyloxyethyl phthalic acid, β-carboxyethyl acrylate, acryloyloxyethyl succinate, methacryloyloxyethyl succinate, 2-propenoic acid, 3- (2-carboxyethoxy) -3-oxypropyl ester, 2-acryloylyl Consisting of oxyethyl tetrahydrophthalic acid, 2-methacryloyloxyethyl tetrahydrophthalic acid, 2-acryloyloxyethyl hexahydrophthalic acid, and 2-methacryloyloxyethyl hexahydrophthalic acid It can contain one or more compounds selected from. The ethylenically unsaturated compound (a2) can further contain a compound having a plurality of ethylenically unsaturated groups. Compounds having a plurality of ethylenically unsaturated groups are, for example, hydroxyl groups such as pentaerythritol triacrylate, pentaerythritol trimethacrylate, trimethylolpropane diacrylate, trimethylolpropane dimethacrylate, dipentaerythritol pentaacrylate, and dipentaerythritol pentamethacrylate. And one or more compounds selected from the group consisting of compounds obtained by reacting a polyfunctional methacrylate with a dibasic acid anhydride.

  In particular, the ethylenically unsaturated compound (a2) preferably contains at least one of acrylic acid and methacrylic acid. In this case, since the ethylenically unsaturated group derived from acrylic acid and methacrylic acid is particularly excellent in photoreactivity, the photoreactivity of the first resin (a) becomes high.

  The amount of the ethylenically unsaturated compound (a2) used is such that the carboxyl group of the ethylenically unsaturated compound is in the range of 0.4 to 1.2 mol with respect to 1 mol of the epoxy group of the epoxy compound The amount is preferably such that the amount of the carboxyl group is in the range of 0.5 to 1.1 mol.

  The compound (a3) selected from the group consisting of polyvalent carboxylic acids and anhydrides used for the synthesis of the first resin (a) is, for example, phthalic acid, tetrahydrophthalic acid, methyltetrahydrophthalic acid, methyl Dicarboxylic acids such as nadic acid, hexahydrophthalic acid, methylhexahydrophthalic acid, succinic acid, methyl succinic acid, maleic acid, citraconic acid, glutaric acid, itaconic acid, etc .; cyclohexane-1,2,4-tricarboxylic acid, trimellitic acid And one or more compounds selected from the group consisting of tribasic or higher polybasic carboxylic acids such as pyromellitic acid, benzophenone tetracarboxylic acid and methylcyclohexene tetracarboxylic acid; and anhydrides of these polybasic carboxylic acids can do.

  The compound (a3) is mainly used to impart re-dispersion and re-solubility to a composition for a solder resist with a dilute aqueous alkali solution by giving an acid value to the first resin (a). The amount of the compound (a3) used is adjusted so that the acid value of the first resin (a) is preferably 30 mg KOH / g or more, particularly preferably 60 mg KOH / g or more. The amount of the compound (a3) used is adjusted so that the acid value of the first resin (a) is preferably 160 mg KOH / g or less, particularly preferably 130 mg KOH / g or less.

  When the first resin (a) is synthesized, the addition reaction of the epoxy compound (a1) with the ethylenically unsaturated compound (a2), and the product (addition reaction product) by this addition reaction and the compound (a3) In order to proceed the addition reaction with (1), known methods can be adopted. For example, in the addition reaction of the epoxy compound (a1) and the ethylenically unsaturated compound (a2), the ethylenically unsaturated compound (a2) is added to a solvent solution of the epoxy compound (a1), and further, thermal polymerization is inhibited if necessary. The reactive solution is obtained by adding and stirring the agent and the catalyst. An addition reaction product is obtained by reacting this reactive solution at a reaction temperature of preferably 60 to 150 ° C., particularly preferably 80 to 120 ° C. in a conventional manner. Examples of the thermal polymerization inhibitor include hydroquinone and hydroquinone monomethyl ether. Examples of the catalyst include tertiary amines such as benzyldimethylamine and triethylamine, quaternary ammonium salts such as trimethylbenzyl ammonium chloride and methyl triethyl ammonium chloride, triphenyl phosphine and triphenyl stibine.

  In order to proceed the addition reaction between the addition reaction product and the compound (a3), the compound (a3) is added to a solvent solution of the addition reaction product, and a thermal polymerization inhibitor and a catalyst are further added if necessary, followed by stirring and mixing. By doing this, a reactive solution is obtained. The first resin (a) is obtained by reacting this reactive solution by a conventional method. The reaction conditions may be the same as in the case of the addition reaction of the epoxy compound and the ethylenically unsaturated compound. As a thermal polymerization inhibitor and a catalyst, the compound used at the time of the addition reaction of an epoxy compound and an ethylenically unsaturated compound provided with a carboxyl group can be used as it is.

  The carboxyl group-containing resin (A) is obtained by reacting an ethylenically unsaturated compound (b2) having an epoxy group with a polymer of the ethylenically unsaturated compound (b1) containing a compound (b11) having a carboxyl group. Resin (second resin (b)) may be contained.

  The ethylenically unsaturated compound (b1) containing the compound (b11) having a carboxyl group used in the synthesis of the second resin (b) may contain only the compound (b11) having a carboxyl group, and the carboxyl You may contain the compound (b11) which has a group, and the compound (b12) which does not have a carboxyl group. Specific examples of the compound (b11) having a carboxyl group include the same compounds as in the case of the ethylenically unsaturated compound (a2) for synthesizing the first resin (a). Specific examples of the compound (b12) having no carboxyl group include the same compounds as in the case of the compound (p2) having no epoxy group.

  Examples of the ethylenically unsaturated compound (b2) having an epoxy group used for the synthesis of the second resin (b) include the same compounds as the compounds (p1) having the above-mentioned epoxy group. The amount of the ethylenically unsaturated compound (b2) used is adjusted so that the acid value of the second resin (b) is preferably 30 mg KOH / g or more, particularly preferably 60 mg KOH / g or more. The amount of the ethylenically unsaturated compound (b2) used is adjusted so that the acid value of the second resin (b) is preferably 160 mg KOH / g or less, particularly preferably 130 mg KOH / g or less.

  When the second resin (b) is synthesized, the polymerization reaction of the ethylenically unsaturated compound (b1) is allowed to proceed according to a known method, for example, when synthesizing the first resin (a). The same method as in the case of polymerizing a saturated compound may be employed. Also as a method of reacting the ethylenically unsaturated compound (b2) with the polymer of the ethylenically unsaturated compound (b1), known methods such as epoxy compound and carboxyl when the first resin (a) is synthesized The same method as in the case of the addition reaction with the ethylenically unsaturated compound carrying the group may be employed.

In the carboxyl group-containing resin (A), an ethylenically unsaturated compound (c2) comprising a carboxyl group at a part of the epoxy groups in the epoxy compound (c1) comprising two or more epoxy groups in one molecule is added and, also contain a resin (third resin (c)) having at least one compound (c3) are added structure selected from the group consisting of polycarboxylic acids and anhydrides thereof to part of another Good.

  As a specific example of an epoxy compound (c1), the compound similar to the case of the said epoxy compound (a1) is mentioned. Specific examples of the ethylenically unsaturated compound (c2) include the same compounds as in the case of the above-mentioned ethylenically unsaturated compound (a2). Specific examples of the compound (c3) include the same compounds as in the case of the above-mentioned compound (a3).

  Although the weight average molecular weight in particular of carboxyl group-containing resin (A) whole is not restrict | limited, The preferable range is 800-100000. Within this range, particularly excellent photosensitivity and resolution are imparted to the composition for solder resist.

  The acid value of the entire carboxyl group-containing resin (A) is preferably 30 mg KOH / g or more, and in this case, the composition for a solder resist is imparted with a good developability. The acid value is more preferably 60 mg KOH / g or more. The acid value of the entire carboxyl group-containing resin (A) is preferably 160 mg KOH / g or less, and in this case, the residual amount of carboxyl groups in the solder resist layer formed from the composition for solder resist is reduced. Good electrical properties, electrical corrosion resistance, water resistance, etc. of the solder resist layer are maintained. The acid value is more preferably 130 mg KOH / g or less.

  The proportion of the carboxyl group-containing resin (A) in the composition for solder resist is not particularly limited, but the content of the carboxyl group-containing resin (A) relative to the total solid content of the composition for solder resist (component constituting the cured product) The proportion is preferably 1% by mass or more, and more preferably 10% by mass or more. The proportion of the carboxyl group-containing resin (A) is preferably 99% by mass or less, and more preferably 80% by mass or less. In this case, good sensitivity and working characteristics of the composition for solder resist and good physical properties of the solder resist layer are sufficiently secured.

  A photoinitiator (B) contains an acyl phosphine oxide type photoinitiator and an alpha-hydroxy acetophenone type photoinitiator. An acyl phosphine oxide type photoinitiator has high reactivity. For this reason, when the coating film of the composition for solder resists is exposed, the photocuring reaction in the inside of the coating film proceeds efficiently. On the other hand, α-hydroxyacetophenone photopolymerization initiators are less susceptible to oxygen damage. For this reason, when the coating film of the composition for solder resists is exposed, the photocuring reaction in the surface layer of the coating film proceeds efficiently. Therefore, the photo-curing reaction proceeds efficiently over the entire coating film of the composition for solder resist. Furthermore, the acyl phosphine oxide type photoinitiator and the alpha-hydroxy acetophenone type photoinitiator do not contain a metal atom which promotes migration. It is considered that this is one of the reasons why the migration in the solder resist layer is suppressed.

  The acyl phosphine oxide type photopolymerization initiator is, for example, 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide (manufactured by BASF Japan Ltd., product name Lucirin TPO), bis (2,4,6-trimethylbenzoyl) -phenyl Phosphine oxide (BASF Japan Ltd., trade name Irgacure 819), 2,4,6-trimethylbenzoyl-ethyl-phenyl-phosphinate (Lambson, trade name SPEEDCURE TPO-L), and bis (2,6-) It can contain one or more compounds selected from the group consisting of dimethoxy benzoyl) -2,4,4-trimethyl-pentyl phosphine oxide (manufactured by BASF Japan Ltd., product name CGI 403).

  Examples of α-hydroxyacetophenone photoinitiators include 1-hydroxy-cyclohexyl-phenyl-ketone (manufactured by BASF Japan Ltd., trade name Irgacure 184), 2-hydroxy-2-methyl-1-phenyl-propan-1-one BASF Japan Ltd., product name Darocur 1173), 1- [4- (2-hydroxyethoxy) -phenyl] -2-hydroxy-2-methyl-1-propan-1-one (BASF Japan Ltd., product name Irgacure) 2959), and 2-hydroxy-1- {4- [4- (2-hydroxy-2-methyl-propionyl) -benzyl] -phenyl} -2-methyl-propan-1-one (manufactured by BASF Japan Ltd., Product name Irgacure 127) or more selected from the group consisting of The above compounds can be contained.

  It is preferable that the ratio of the acyl phosphine oxide type photoinitiator with respect to solid content whole quantity of the composition for solder resists exists in the range of 0.1-20 mass%. Moreover, it is preferable that the ratio of the (alpha)-hydroxy acetophenone type photoinitiator with respect to solid content whole quantity of the composition for solder resists exists in the range of 0.1-20 mass%. In this case, the photocurability of the composition for solder resist is particularly high, the hardness of the solder resist layer is particularly high, and the developer resistance of the solder resist layer is particularly high.

  The photopolymerization initiator (B) may further contain a compound other than the acyl phosphine oxide photopolymerization initiator and the α-hydroxyacetophenone photopolymerization initiator. For example, the photopolymerization initiator (B) is benzoin and its alkyl ethers; acetophenones such as acetophenone and benzyldimethyl ketal; anthraquinones such as 2-methylanthraquinone; 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone And thioxanthones such as 2-isopropyl thioxanthone, 4-isopropyl thioxanthone and 2,4-diisopropyl thioxanthone; benzophenones such as benzophenone and 4-benzoyl-4'-methyl diphenyl sulfide; xanthones such as 2,4-diisopropyl xanthone; Α-hydroxy ketones such as 2-hydroxy-2-methyl-1-phenyl-propan-1-one; and 2-methyl-1- [4- (methylthio) phenyl] -2-morpholino-1-propa Compounds nitrogen atom one or more selected from the group consisting of compounds containing of such emissions may further contain.

  The proportion of the photopolymerization initiator (B) in the composition for solder resist takes into account, for example, the balance between the photocurability of the composition for solder resist and the physical properties of the solder resist layer formed from the composition for solder resist. Are set appropriately. It is preferable that the ratio of a photoinitiator (B) with respect to solid content whole quantity of the composition for solder resists is in the range of 0.01-10 mass% especially.

  The thixotropic agent (C) contains a swellable layered silicate. Swellable layered silicates have a tetrahedral structure in which oxygen ions are coordinated to silicon, a tetrahedral structure in which oxygen ions are coordinated to aluminum ions, oxygen to aluminum, magnesium, iron ions, etc. It is an inorganic polymer having an octahedral structure and the like configured by coordination of hydroxide ions and the like. The swellable layered silicate has a crystal structure in which, for example, a negatively charged silicate sheet having a thickness of about 1 nm and a cation such as sodium ion having a positive charge are regularly stacked in layers. Swellable layered silicates have, for example, micron-sized particle sizes. Swellable layered silicates have the property of being easily swelled by the incorporation of polar molecules between the layers, and cation exchange properties derived from cations such as sodium ions present in the layers.

  Swellable layered silicates are, for example, smectite clay minerals such as montmorillonite, beidellite, hectorite, saponite, stevensite, nontronite, sauconite, various clay minerals such as vermiculite, halloysite, kanemite, kenyaite, zirconium phosphate, titanium phosphate; And one or more materials selected from the group consisting of swellable micas such as Li-type fluorotheniolite, Na-type fluorotheniolite, Na-type tetrasilicon fluoromica, Li-type tetrasilicon fluoromica and the like. The swellable layered silicate may be a natural product or a synthetic product. In particular, the swellable layered silicate preferably contains bentonite containing montmorillonite as a main component. The swellable layered silicate may contain impurities such as quartz, cristobalite, zeolite, feldspar, calcite, and dolomite.

  The swellable layered silicate is, for example, a commercially available product Leox AG organic bentonite (Bentone series (Bentone SD-1, Benton SD-2, Benton 27, Benton 34, Benton 38)), organic bentonite manufactured by Hojun Co., Ltd. (Esben series (Esben, Esben C, Esben E, Esben W, Esben WX), Organite series (Organite, Organite T), Esben N series (Esben N-400, Esben NX, Esben NX 80, Esben NTO, One or more selected from the group consisting of Esben NZ, Esben NZ70, Esben NE, Esben NEZ, Esben NO12S, Esben NO12), organic bentonite (Orben series (Orben D, New D olben)) manufactured by Shiroishi Kogyo Co., Ltd. The material It may have.

  The thixotropy of the composition for solder resist is adjusted by appropriately adjusting the proportion of the swellable layered silicate in the composition for solder resist.

  The proportion of the swellable layered silicate relative to the total solid content of the composition for a solder resist is not particularly limited, but is set, for example, in the range of 0.05 to 10% by mass.

  The thixotropic agent (C) may further contain a material other than the swellable layered silicate. For example, the thixotropic agent (C) may be kaolinite, sericite, illite, gluconite, chlorite, talc, zeolite, modified castor oil, amide wax, polyethylene oxide, polyurethane, modified urea, high molecular weight urea derivative, urea. It may further contain one or more materials selected from the group consisting of modified polyamide and urea modified urethane.

  However, in order to suppress migration, it is preferable that the content of silica particles such as aerosil in the composition for a solder resist is small, or that the composition for a solder resist does not contain silica particles. Silica particles are conventionally and widely used as a thixotropic agent, but when the composition for a solder resist contains silica particles, migration tends to occur. Although the reason is not clear yet, it is speculated that the high water absorption of the silica particles and the large surface area of the silica particles promote the occurrence of migration. In addition, metal ions mixed in the silica particles are presumed to be involved in the generation of migration. In order to sufficiently suppress migration, the amount of silica particles is preferably 2.5 parts by mass or less based on 100 parts by mass of the solid content of the carboxyl group-containing resin (A) in the composition for a solder resist.

  The composition for solder resist may further contain an epoxy compound (D) having two or more epoxy groups in one molecule. In this case, the composition for solder resist is provided with a thermosetting property. The epoxy compound (D) may be a solvent-insoluble epoxy compound, or may be a general-purpose solvent-soluble epoxy compound or the like.

  The epoxy compound (D) is, in particular, a phenol novolac epoxy resin (specifically, part number EPICLON N-775 manufactured by DIC Corporation), a cresol novolac epoxy resin (specifically, part number EPICLON N-695 manufactured by DIC Corporation), Bisphenol A type epoxy resin (Specific example: No. jER1001 manufactured by Mitsubishi Chemical Co., Ltd.), bisphenol A-novolac type epoxy resin (Specific example: No. EPICLON N-865 made by DIC Corporation), bisphenol F type epoxy resin (Specific example: As Mitsubishi Chemical Co., Ltd., product number jER4004), bisphenol S type epoxy resin (as a specific example, product number from DIC Corporation, EPICLON EXA-1514), bisphenol AD type epoxy resin, biphenyl type epoxy resin (As a specific example, No. YX4000 made by Mitsubishi Chemical Co., Ltd.), Biphenyl novolac epoxy resin (as No. NC-3000 made as Nippon Kayaku Co., Ltd. as a specific example), Hydrogenated bisphenol A type epoxy resin (As a specific example, Nippon Steel Sumikin Chemical Part No. ST-4000D, Inc., naphthalene type epoxy resin (as specific example, part number EPICLON HP-4032, EPICLON HP-4700, EPICLON HP-4770, manufactured by DIC Corporation), special bifunctional epoxy resin (as specific example) Part No. YL7175-500 and YL7175-1000, manufactured by Mitsubishi Chemical Corporation; part No. EPICLON TSR-960, EPICLON TER-601, EPICLON TSR-250-80BX, EPICLON 1650-7, manufactured by DIC Corporation It is selected from the group consisting of MPX, EPICLON EXA-4850, EPICLON EXA-4816, EPICLON EXA-4822, and EPICLON EXA-9726; product number YSLV-120TE manufactured by Nippon Steel Sumikin Chemical Co., Ltd., and bisphenol epoxy resins other than the above. It is preferable to contain one or more compounds. The triglycidyl isocyanurate preferably contains a β-form having a structure in which three epoxy groups are bonded in the same direction, particularly to the s-triazine ring skeleton surface. The triglycidyl isocyanurate may contain a β form and an α form having a structure in which one epoxy group is bonded to the S-triazine ring skeleton surface in a direction different from that of the other two epoxy groups.

It is also preferred that the epoxy compound (D) contains a phosphorus-containing epoxy resin. In this case, the flame retardancy of the cured product of the composition for solder resist is improved. Specific examples of phosphorus-containing epoxy resin include phosphoric acid-modified bisphenol F-type epoxy resin (specific example, part number EPIC L ON EXA-9726 and EPICLON EXA-9710 manufactured by DIC Corporation), part number Epototo manufactured by Nippon Steel Sumikin Chemical Co., Ltd. FX-305 is mentioned.

  It is preferable that the ratio of the epoxy compound (D) with respect to the solid content whole quantity of the composition for solder resists exists in the range of 0.1-50 mass%.

  When the composition for solder resist is not required to have a thermosetting property, the composition for solder resist may not contain the epoxy compound (D).

  It is also preferable that the composition for solder resist contains a photopolymerizable compound (E) other than the carboxyl group-containing resin (A). The photopolymerizable compound (E) can contain one or more compounds selected from the group consisting of photopolymerizable monomers and photopolymerizable prepolymers. The photopolymerizable compound (E) is used, for example, for the purpose of dilution of the composition for solder resist, viscosity adjustment, adjustment of acid value, adjustment of photopolymerization, and the like.

  The photopolymerizable compound (E) is, for example, monofunctional (meth) acrylate such as 2-hydroxyethyl (meth) acrylate; and diethylene glycol di (meth) acrylate, trimethylolpropane di (meth) acrylate, trimethylolpropane tri (meth) ) Polyacrylates such as acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, ε-caprolactone modified pentaerythritol hexaacrylate, etc. It can contain one or more compounds selected from the group consisting of (meth) acrylates.

  It is also preferable that the photopolymerizable compound (E) contains a phosphorus-containing compound (phosphorus-containing photopolymerizable compound). In this case, the flame retardancy of the cured product of the composition for solder resist is improved. The phosphorus-containing photopolymerizable compound is, for example, 2-methacryloyloxyethyl acid phosphate (as a specific example, product number light ester P-1M and light ester P-2M manufactured by Kyoeisha Chemical Co., Ltd.), 2-acryloyloxyethyl acid phosphate (Specific example, product number light acrylate P-1A manufactured by Kyoeisha Chemical Co., Ltd.), diphenyl-2-methacryloyloxyethyl phosphate (specific example, product number MR-260 manufactured by Daihachi Kogyo Co., Ltd.), and Showa Highpolymer Co., Ltd. HFA series (as an example, product number HFA-6003 which is an addition reaction product of dipentaerythritol hexaacrylate and HCA, and product number which is an addition reaction product of HFA-6007, caprolactone modified dipentaerythritol hexaacrylate and HCA HFA-3 03, and may contain one or more compounds selected from the group consisting of HFA-6127, etc.).

  When the photopolymerizable compound (E) is used, the ratio of the photopolymerizable compound (E) to the composition for a solder resist is preferably in the range of 0.05 to 40% by mass. Furthermore, it is desirable that the ratio of the photopolymerizable compound (E) to the total solid content of the composition for solder resist is 50% by mass or less. In this case, the surface tackiness of the dry film formed from the composition for solder resist is prevented from becoming too strong.

  The composition for solder resist may contain a filler (F). In this case, the cure shrinkage of the coating film formed from the composition for solder resist is reduced. The filler (F) can contain, for example, one or more materials selected from the group consisting of barium sulfate, titanium oxide, carbon nanotubes, aluminum hydroxide, and magnesium hydroxide.

  The composition for solder resist may be whitened by incorporating a white powder in the filler (F). In this case, a white solder resist layer is formed using the composition for solder resist. The white powder can contain, for example, one or more materials selected from the group consisting of titanium oxide powder and barium sulfate powder.

  Although the ratio of the filler in the composition for solder resists is set suitably, it is preferable to exist in the range of 10-50 mass%. In this case, the solid content of the composition for the solder resist is sufficiently high, which suppresses the volume change when the composition for the solder resist is heated and dried, thereby improving the crack resistance of the solder resist layer. .

  The composition for solder resist may contain an organic solvent (G). The organic solvent (G) is used for the purpose of liquefaction or varnishing of the composition for solder resist, viscosity adjustment, adjustment of coating property, adjustment of film forming property, and the like.

  Organic solvents (G) are, for example, straight-chain, branched, secondary or polyvalent alcohols such as ethanol, propyl alcohol, isopropyl alcohol, hexanol and ethylene glycol; ketones such as methyl ethyl ketone and cyclohexanone; and aromatic substances such as toluene and xylene Aromatic hydrocarbons such as Swazole series (made by Maruzen Petrochemical Co., Ltd.) and Solvesso series (made by Exxon Chemical Co., Ltd.); Cellosolves such as cellosolve and butyl cellosolve; carbitol and butyl carbitol Carbitols such as propylene glycol alkyl ethers such as propylene glycol methyl ether Polypropylene glycol alkyl ethers such as dipropylene glycol methyl ether Ethyl acetate, butyl acetate, cellosolve acetate etc It can contain, as well as one or more compounds selected from the group consisting of dialkyl glycol ethers; acetic acid esters.

  The proportion of the organic solvent (G) in the composition for solder resist is such that the organic solvent (G) evaporates quickly at the time of temporary drying of the coating film formed from the composition for solder resist, that is, the organic solvent (G) It is preferable to adjust so that it does not remain in a dry film. In particular, the proportion of the organic solvent (G) in the composition for solder resist is preferably in the range of 5 to 99.5% by mass. In this case, good coatability of the composition for solder resist can be obtained. In addition, since the suitable ratio of an organic solvent (G) changes with the coating methods etc., it is preferable that a ratio is suitably adjusted according to a coating method.

  The composition for a solder resist may further contain a resin other than the carboxyl group-containing resin (A) and the epoxy compound (D) without departing from the subject matter of the present invention. For example, the composition for solder resist may be a tolylene diisocyanate type blocked with caprolactam, oxime, malonic acid ester, etc., a morpholine diisocyanate type, an isophorone diisocyanate type and a blocked isocyanate group of hexamethylene diisocyanate; melamine, n-butylated melamine Amino resins such as resin, isobutylated melamine resin, butylated urea resin, butylated melamine urea cocondensing resin, benzoguanamine cocondensed resin; various thermosetting resins other than the above; UV curable epoxy (meth) acrylate; bisphenol A Resins obtained by adding (meth) acrylic acid to epoxy resins such as epoxy resin, phenol novolac resin, cresol novolac resin and alicyclic resin; and diallyl phthalate resin, phenoxy resin, melamine resin, Urethane resin, may contain one or more resins that are selected from the group consisting of a polymer compound such as a fluorine resin.

  The composition for solder resist may further contain an appropriate additive as required. For example, a composition for solder resist is a curing agent for curing an epoxy compound; a curing accelerator; a colorant such as a pigment; a copolymer such as silicone or acrylate; a leveling agent; an adhesion imparting agent such as a silane coupling agent A thixotropic agent, a polymerization inhibitor, an antihalation agent, a flame retardant, an antifoaming agent, an antioxidant, a surfactant, and a polymer dispersant, and may contain one or more compounds selected from the group consisting of

  The raw material of the composition for solder resist as described above is blended, and for example, the composition for solder resist can be prepared by kneading according to a known kneading method using a triple roll, ball mill, sand mill or the like.

  In consideration of storage stability and the like, the first agent may be prepared by mixing a part of the material of the composition for a solder resist, and the second agent may be prepared by mixing the rest of the material. For example, the first agent is prepared by mixing and dispersing the photopolymerizable compound (E), a part of the organic solvent (G) and the epoxy compound (D) among the raw materials to prepare the first agent, and The second agent may be prepared by dispersing it. In this case, the composition for a solder resist can be prepared by mixing the first agent and the second agent in a necessary amount.

  The composition for solder resist according to the present embodiment is applied, for example, to form a solder resist layer on a printed wiring board.

  Below, the 1st aspect of the method of forming a soldering resist layer in a printed wiring board using the composition for soldering resists by this embodiment is shown. In this embodiment, a solder resist layer is formed from a composition for a solder resist having both photosensitivity and thermosetting properties.

  First, prepare a printed wiring board. The composition for a solder resist is applied on the first surface of the printed wiring board to form a coating film, and then the solder resist is also formed on the second surface of the printed wiring board opposite to the first surface. The coating composition is applied to form a coating. The composition for solder resist may be applied simultaneously on the first surface and the second surface to form a coating. The method of applying the composition for solder resist is selected from the group consisting of known methods such as dipping, spraying, spin coating, roll coating, curtain coating and screen printing. Then, in order to volatilize the organic solvent in the composition for solder resists as needed, a coating film is dried by performing pre-drying, for example under the temperature within the range of 60-120 degreeC.

  In forming a coating film on a printed wiring board, a coating composition (dry film) is formed by applying a composition for a solder resist in advance on a suitable support and then drying, and the dry film is printed wiring The dry film may be transferred onto the printed wiring board by applying pressure to the dry film and the printed wiring board after stacking on the board (dry film method). In this case, preliminary drying may be omitted.

  Subsequently, a negative mask on which a pattern has been drawn is applied to the surface of the dried film directly or indirectly on the coating, and then the coating is exposed to light through the negative mask by irradiation with active energy rays. As a negative mask, a phototool such as a mask film or a dry plate, in which the pattern shape of the solder resist layer is drawn as an exposed portion transmitting active energy rays and the other portion is formed as a non-exposed portion shielding active energy rays. Etc. are used. The active energy ray is selected according to the composition of the composition for a solder resist, and examples thereof include ultraviolet light, visible light and near infrared light. When the active energy ray is an ultraviolet ray, the light source is selected from the group consisting of, for example, chemical lamps, low pressure mercury lamps, medium pressure mercury lamps, high pressure mercury lamps, ultra high pressure mercury lamps, xenon lamps and metal halide lamps.

  A method other than the method using a negative mask may be adopted as the exposure method. For example, a direct drawing method such as laser exposure may be employed.

  After exposure of the coating film, the negative mask is removed from the printed wiring board, and the coating film is developed to remove the non-exposed part of the coating film. Then, exposed portions of the coating film remain on the first surface and the second surface of the printed wiring board. The exposed part of this coating film constitutes a solder resist layer.

  In the development processing, an appropriate developer can be used according to the composition of the composition for a solder resist. Specific examples of the developer include sodium carbonate aqueous solution, potassium carbonate aqueous solution, ammonium carbonate aqueous solution, sodium hydrogencarbonate aqueous solution, potassium hydrogencarbonate aqueous solution, ammonium hydrogencarbonate aqueous solution, sodium hydroxide aqueous solution, potassium hydroxide aqueous solution, ammonium hydroxide aqueous solution, water Examples thereof include alkaline solutions such as tetramethyl ammonium oxide aqueous solution and lithium hydroxide aqueous solution. As the developer, organic amines such as monoethanolamine, diethanolamine, triethanolamine, monoisopropanolamine, diisopropanolamine, triisopropanolamine and the like can also be used. Among these developing solutions, only one type may be used, or two or more types may be used in combination. When the developer is an alkaline solution, the solvent may be water alone or a mixture of water and a hydrophilic organic solvent such as lower alcohols.

  If necessary, the solder resist layer may be subjected to a heat treatment, for example, in the range of a heating temperature of 120 to 180 ° C., for a heating time of 30 to 90 minutes. In this case, the thermosetting reaction of the solder resist layer can proceed. Thereby, performances such as strength, hardness and chemical resistance of the solder resist layer are improved.

  In addition, the timing which exposes and develops the coating film of the composition for solder resists is not restricted to this aspect. For example, first, a coating film is formed on the first surface of a printed wiring board, exposed and developed to form a solder resist layer on the first surface, and then similarly on the second surface. A solder resist layer may be formed.

  Further, if necessary, the solder resist layer may be further irradiated with ultraviolet light after the solder resist layer is subjected to heat treatment. In this case, the photocuring reaction of the solder resist layer can be further advanced. This further improves the migration resistance of the solder resist layer.

[Preparation of Carboxyl Group-Containing Resin Solution A-1]
Cresol novolac epoxy resin (manufactured by Nippon Steel & Sumikin Chemical Co., Ltd., product number YDCN-700-5, epoxy equivalent 203) 203 parts by mass in a four-necked flask attached with a reflux condenser, a thermometer, an air blowing pipe and a stirrer A mixture was prepared by adding 103 parts by mass of diethylene glycol monoethyl ether acetate, 0.2 parts by mass of methyl hydroquinone, 72 parts by mass of acrylic acid, and 1.5 parts by mass of triphenylphosphine. The addition reaction was allowed to proceed by heating this mixture under the conditions of a heating temperature of 110 ° C. and a heating time of 10 hours. Subsequently, 60.8 parts by mass of tetrahydrophthalic anhydride and 78.9 parts by mass of diethylene glycol monoethyl ether acetate were added to the mixture, and the mixture was further heated at a heating temperature of 80 ° C. for 3 hours. Thereby, the 65 mass% solution (carboxyl group containing resin solution A-1) of carboxyl group containing resin was obtained.

[Preparation of Carboxyl Group-Containing Resin Solution A-2]
Cresol novolac epoxy resin (manufactured by Nippon Steel & Sumikin Chemical Co., Ltd., product number YDCN-700-5, epoxy equivalent 203) 203 parts by mass in a four-necked flask attached with a reflux condenser, a thermometer, an air blowing pipe and a stirrer A mixture was prepared by adding 105 parts by mass of diethylene glycol monoethyl ether acetate, 0.2 parts by mass of methyl hydroquinone, 43.2 parts by mass of acrylic acid, and 3 parts by mass of triphenylphosphine. The mixture was heated under the conditions of a heating temperature of 100 ° C. and a heating time of 3 hours. Subsequently, 68 parts by mass of tetrahydrophthalic acid, 0.3 parts by mass of methylhydroquinone and 65 parts by mass of diethylene glycol monoethyl ether acetate were added to the mixture, and the mixture was heated under the conditions of a heating temperature of 110 ° C. and a heating time of 6 hours. Thereby, the 65 mass% solution (carboxyl group containing resin solution A-2) of carboxyl group containing resin was obtained.

[Preparation of composition for solder resist]
In each Example and Comparative Example, the mixture was obtained by mix | blending the raw material shown to the following table. The composition for a solder resist was obtained by kneading this mixture with a three-roll mill.

The details of the components shown in the table are as follows.
Epoxy compound A: biphenyl type epoxy resin, manufactured by Mitsubishi Chemical Corporation, part number YX4000.
Epoxy compound B: cresol novolac epoxy resin, manufactured by DIC Corporation, part number EPICLON N-695.
-Acyl phosphine oxide type photoinitiator A-1: 2,4, 6- trimethyl benzoyl diphenyl phosphine oxide, made by BASF, product number Lucirin TPO.
-Acyl phosphine oxide type | system | group photoinitiator A-2: bis (2,4,6- trimethyl benzoyl)-phenyl phosphine oxide, the BASF company make, product number Irgacure 819.
Α-hydroxyacetophenone photopolymerization initiator B-1: 1-hydroxy-cyclohexyl-phenyl-ketone, manufactured by BASF, product number Irgacure 184.
-(Alpha)-hydroxy acetophenone type photoinitiator B-2: 2-hydroxy- 2-methyl- 1-phenyl- propan 1-one, the BASF company make, product number Darocur 1173.
Photopolymerization initiator C-1: 2-methyl-1- (4-methylthiophenyl) -2-morpholinopropan-1-one, manufactured by BASF, product number Irgacure 907.
Photopolymerization initiator C-2: 2,4-diethylthioxanthone, manufactured by Nippon Kayaku Co., Ltd., product number Kayacure DETX-S.
Photopolymerization initiator C-3: 4,4′-bis (diethylamino) benzophenone, manufactured by Hodogaya Chemical Industry Co., Ltd., part number EAB.
Photopolymerizable compound: dipentaerythritol hexaacrylate, manufactured by Nippon Kayaku Co., Ltd., part number KAYARAD DPHA.
Swellable layered silicate (organic bentonite): manufactured by Leox, product number Benton SD-2.
Fine powder silica: manufactured by Tokuyama Co., Ltd., part number MT-10.
Barium sulfate: manufactured by Sakai Chemical Industry Co., Ltd., part number Variace B30.
-Talc: manufactured by Toshin Kasei Co., Ltd., part number SG2000.
Melamine resin: manufactured by Nissan Chemical Industries, Ltd., part number melamine HM.
Antifoaming agent: simethicone (a mixture of dimethicone and silicic acid), manufactured by Shin-Etsu Silicone Co., Ltd., part number KS-66.
Organic solvent A: aromatic mixed solvent (petroleum naphtha).
Organic solvent B: diethylene glycol monoethyl ether acetate.

[Evaluation test]
(Preparation of test piece)
First, the copper foil was patterned by performing an etching process on a glass-based epoxy resin copper-clad laminate provided with a copper foil having a thickness of 35 μm, thereby obtaining a printed wiring board.

  The composition for a solder resist obtained in each Example and Comparative Example was applied on the printed wiring board by screen printing to form a wet coating film on the printed wiring board. The wet coating was predried by heating at a heating temperature of 80 ° C. for a heating time of 40 minutes. Thus, a dried coating film having a thickness of 20 μm was formed.

A negative mask was directly applied on the dried coating film, and the dried coating film was irradiated with ultraviolet light of the optimum exposure amount through the negative mask. Thereby, the dried coating film was selectively exposed. Subsequently, the dry coating film after the exposure was subjected to a development treatment using an aqueous solution of sodium carbonate, whereby a portion (cured film) hardened by the exposure of the dry coating film was left on the printed wiring board. The cured film was further heated at 150 ° C. for 60 minutes to be thermally cured, and subsequently the cured film was irradiated with ultraviolet light of 1000 mJ / cm ² . Thereby, a solder resist layer was formed on a printed wiring board, and the printed wiring board provided with this solder resist layer was used as a test piece.

(Tackiness)
The tackiness (tackiness) of the dried coating was evaluated as shown below when the negative mask was removed at the time of exposure during test piece production.
3: No resistance was observed when removing the negative mask, and no mark of the negative mask was observed in the dried coating.
2: When the negative mask was removed, slight resistance was observed, and marks of the negative mask were observed in the dried coating.
1: It was difficult to remove the negative mask, and if it was removed forcibly, the dried coating was damaged.

(Adhesiveness)
According to the test method defined in JIS D0202, cross-cuts were placed in a grid pattern in the solder resist layer of the test piece, and then a peeling test using a cellophane adhesive tape was performed. The state of peeling after the test was visually observed. The results were evaluated as follows.
3: There is no change in all of the 100 crosscuts.
2: Peeling occurred at 1 to 10 places in 100 cross-cut portions.
Peeling occurred at 11 to 100 places in the 1: 100 cross cut portion.

(Pencil hardness)
The pencil hardness of the solder resist layer of the test piece was measured using Mitsubishi Hyuni (manufactured by Mitsubishi Pencil Co., Ltd.) as a pencil in accordance with the provisions of JIS K5400.

(Acid resistant)
After immersing the test piece in a 10% aqueous sulfuric acid solution for 30 minutes at room temperature, the appearance of the solder resist layer was observed. The results were evaluated as follows.
3: No abnormality such as blistering, peeling or discoloration was observed in the solder resist layer.
2: A slight abnormality such as blistering, peeling, or discoloration is observed in the solder resist layer.
1: Abnormality such as blistering, peeling, or discoloration is noticeable in the solder resist layer.

(Alkali resistance)
After immersing the test piece in a 10% by mass aqueous solution of sodium hydroxide at room temperature for 1 hour, the appearance of the solder resist layer was observed. The results were evaluated as follows.
3: No abnormality such as blistering, peeling or discoloration was observed in the solder resist layer.
2: A slight abnormality such as blistering, peeling, or discoloration is observed in the solder resist layer.
1: Abnormality such as blistering, peeling, or discoloration is noticeable in the solder resist layer.

(Solder heat resistance)
A water soluble flux (London Chemical Co., product number LONCO 3355-11) was applied to the solder resist layer of the test piece, and then the solder resist layer was immersed in a molten solder bath at 260 ° C. for 10 seconds and then washed with water. After this process was repeated three times, the appearance of the solder resist layer was observed, and the results were evaluated as follows.
3: No abnormality such as blistering, peeling or discoloration was observed in the solder resist layer.
2: A slight abnormality such as blistering, peeling, or discoloration is observed in the solder resist layer.
1: Abnormality such as blistering, peeling, or discoloration is noticeable in the solder resist layer.

(Plating resistance)
The electroless nickel plating and the electroless gold plating were sequentially applied to the test piece using a commercially available plating solution, and then the states of the plating layer and the solder resist layer were confirmed.

  Subsequently, the adhesion state of the solder resist layer after plating was confirmed by conducting a cellophane adhesive tape peeling test of the solder resist layer.

The results were evaluated as follows.
3: No change in appearance was observed in the solder resist layer before and after the formation of the plating layer, no penetration of plating was observed, and peeling of the solder resist layer was not observed in the cellophane adhesive tape peeling test.
2: No change in appearance is observed in the solder resist layer before and after formation of the plating layer, but partial peeling of the solder resist layer is observed in the cellophane adhesive tape peeling test.
1: Swelling of the solder resist layer is observed after formation of the plating layer, and peeling of the solder resist layer is observed in the cellophane adhesive tape peeling test.

(PCT resistant)
After leaving the test piece in saturated steam at a temperature of 121 ° C. for 8 hours, the appearance of the solder resist layer of the test piece was observed. The results were evaluated as follows.
3: No abnormality such as blistering, peeling or discoloration was observed in the solder resist layer.
2: A slight abnormality such as blistering, peeling, or discoloration is observed in the solder resist layer.
1: Abnormality such as blistering, peeling, or discoloration is noticeable in the solder resist layer.

(Electrical insulation)
A printed wiring board for evaluation was obtained by forming a comb-shaped electrode having a line width / space width of 100 μm / 100 μm on a FR-4 type copper-clad laminate. A solder resist layer was formed on this printed wiring board by the same method and conditions as in the case of producing a test piece. Subsequently, while applying a bias voltage of DC 12 V to the comb-shaped electrodes, the printed wiring board was subjected to 121 ° C., 97% R. H. It was exposed for 150 hours under the test environment of The electrical resistance value of the solder resist layer under this test environment was constantly measured. The results were evaluated according to the following evaluation criteria.
3: The electrical resistance value was always 10 ⁶ Ω or more until 150 hours elapsed from the start of the test.
2: The electrical resistance was 10 ⁶ Ω or more until at least 100 hours elapsed from the start of the test, but the electrical resistance became less than 10 ⁶ Ω at 150 hours after the start of the test.
1: The electrical resistance value was less than 10 ⁶ Ω before 100 hours from the start of the test.

Claims (5)

A carboxyl group-containing resin (A) having an ethylenically unsaturated group, a photopolymerization initiator (B), a thixotropic agent (C), and barium sulfate,
An ethylenically unsaturated compound (c2) in which the carboxyl group-containing resin (A) comprises a carboxyl group in a part of the epoxy groups in the epoxy compound (c1) comprising two or more epoxy groups in one molecule A resin (c) having a structure in which at least one compound (c3) selected from the group consisting of a polyvalent carboxylic acid and an anhydride thereof is added to another portion, and the photopolymerization initiator ( B) contains an acyl phosphine oxide type photopolymerization initiator and an α-hydroxyacetophenone type photopolymerization initiator, the thixotropic agent (C) contains a swellable layered silicate, and the above with respect to the total solid content the proportion of the swellable layered silicate, 0.05% by mass or more 10 wt% or less (excluding 10 mass%) solder resist composition characterized der Rukoto. The carboxyl group-containing resin (A) is
An ethylenically unsaturated compound (a2) having a carboxyl group is addition-reacted to at least one of the epoxy groups in the epoxy compound (a1) having two or more epoxy groups in one molecule, and a polyvalent carboxylic acid The composition for a solder resist according to claim 1, further comprising a resin (a) having a structure to which at least one compound (a3) selected from the group consisting of and anhydrides thereof is added. The composition for a solder resist according to claim 1, further comprising an epoxy compound (D) having two or more epoxy groups in one molecule. It further contains a photopolymerizable compound (E),
The solder according to any one of claims 1 to 3, wherein the photopolymerizable compound (E) contains one or more compounds selected from the group consisting of photopolymerizable monomers and photopolymerizable prepolymers. Resist composition. A printed wiring board comprising a solder resist layer formed from the composition for a solder resist according to any one of claims 1 to 4.