JP6204734B2 - Resin composition for solder resist - Google Patents

Description

The present invention relates to Luso Ruda resist resin composition suitably used for formation of a printed wiring board solder resist layer.

  Conventionally, various photosensitive resin compositions have been used to form a solder resist layer on a printed wiring board.

  In recent years, printed circuit boards have been increased in density as electronic devices have become lighter, thinner, and shorter, and higher performance of the solder resist layer is required in response to this. That is, the resin composition for forming the solder resist layer is required to have an excellent solder resist layer that sufficiently satisfies the properties such as substrate adhesion, heat resistance, chemical resistance, and electrical insulation. Has been.

  Conventionally, for example, in Patent Document 1, (A) one or two or more types of monocarboxylic acid per one equivalent of an epoxy group is added to an epoxy group of a resin (a) having two or more epoxy groups in one molecule. (B) is reacted at a ratio of 0.3 to 0.9 moles in total, and the polybasic acid (d) is added to the epoxy group of the obtained reaction product (c) with respect to 1 equivalent of the epoxy group. A carboxyl group-containing resin obtained by reacting at a rate of 0.0 to 5.0 mol, an acid value of 20 to 200 mg KOH / g, and soluble in an organic solvent, (B) a carboxyl group-containing compound, A resin composition containing (C) a photosensitive (meth) acrylate compound and (D) a photopolymerization initiator has been proposed.

JP 2010-31072 A

  With the recent increase in the density of printed wiring boards, the resin composition for solder resist and the solder resist layer are required to have further improved performance. In particular, the dried coating film formed from the resin composition for solder resist In addition to further reducing the tackiness, it is required to further improve the adhesion between the solder resist layer obtained by curing this and the substrate.

  However, the solder resist layer is also required to have characteristics such as alkali developability, electroless gold plating resistance, PCT resistance, and electrical insulation. While maintaining these properties, a means for simultaneously reducing the tackiness of the dried coating film formed from the resin composition for solder resist and improving the adhesion between the solder resist layer and the substrate has not yet been obtained. .

The present invention has been made in view of the above reasons, and its purpose is to reduce the tackiness of the dried coating film and to improve the adhesion to the substrate while simultaneously maintaining other characteristics high. and to provide a forming a solder resist layer obtained Luso Ruda resist resin composition capable.

The photosensitive resin according to the first aspect of the present invention has a structure in which an ethylenically unsaturated compound having a carboxyl group is added to an epoxy resin, and a polybasic acid anhydride is further added.
The epoxy resin is a bifunctional epoxy resin;
The polybasic acid anhydride contains a compound having a structure represented by the following structural formula (1).

  In the second embodiment of the present invention, in the first embodiment, the bifunctional epoxy resin contains at least one selected from a bisphenol A type epoxy resin and a bisphenol F type epoxy resin.

  The solder resist resin composition according to the third aspect of the present invention contains the photosensitive resin according to the first or second aspect.

  According to the present invention, while the tackiness of the dried coating film is reduced, the adhesion to the substrate is improved, and at the same time, characteristics such as alkali developability, electroless gold plating resistance, PCT resistance, and electrical insulation are maintained high. The photosensitive resin which can form the soldering resist layer which can be obtained, and the resin composition for soldering resists containing this photosensitive resin are obtained.

  Hereinafter, modes for carrying out the present invention will be described.

  The photosensitive resin according to the present embodiment (hereinafter referred to as the first photosensitive resin) has a structure in which an ethylenically unsaturated compound having a carboxyl group is added to an epoxy resin and a polybasic acid anhydride is further added. . The epoxy resin in this case is a bifunctional epoxy resin. Furthermore, the polybasic acid anhydride contains a compound having a structure represented by the following structural formula (1).

  The addition reaction between the epoxy resin and the ethylenically unsaturated compound having a carboxyl group is a ring-opening addition reaction involving the epoxy group in the epoxy resin and the carboxyl group in the ethylenically unsaturated compound having a carboxyl group. Hydroxyl groups are produced in the product of the addition reaction (addition reaction product).

  Examples of the addition reaction between the addition reaction product and the polybasic acid anhydride include the following three aspects. By these aspects, a carboxyl group is generated in the first photosensitive resin.

  In the first aspect, at least a part of the hydroxyl groups originally contained in the epoxy resin reacts with the acid anhydride group in the polybasic acid anhydride. Thereby, a carboxyl group is generated in the first photosensitive resin.

  In the second aspect, at least a part of the hydroxyl group generated in the addition reaction product by the ring-opening addition reaction of the carboxyl group in the ethylenically unsaturated compound having an epoxy group and a carboxyl group in the epoxy resin, and a polybasic The acid anhydride group in the acid anhydride reacts. Thereby, a carboxyl group is generated in the first photosensitive resin.

  In the third aspect, at least a part of the hydroxyl groups that the epoxy resin originally has reacts with the acid anhydride groups in the polybasic acid anhydride, and the epoxy groups and carboxyls in the epoxy resin described above. At least a part of the hydroxyl groups generated in the addition reaction product by the ring-opening addition reaction of the carboxyl group in the ethylenically unsaturated compound having a group reacts with the acid anhydride group in the polybasic acid anhydride. Thereby, a carboxyl group is generated in the first photosensitive resin.

  The first photosensitive resin can contain one or more resins among the resins according to the first to third aspects.

  Since the first photosensitive resin can be produced by the reaction as described above, an ethylenically unsaturated bond derived from an ethylenically unsaturated compound having a carboxyl group and a carboxyl group derived from a polybasic acid anhydride. Have. Thereby, photocurability and alkali developability are provided to the resin composition for solder resist.

  The epoxy resin that can be used to synthesize the first photosensitive resin, the ethylenically unsaturated compound having a carboxyl group, and the polybasic acid anhydride will be described in more detail.

  In the present embodiment, the epoxy resin is selected from bisphenol A type epoxy resin (specifically, product number jER1001 manufactured by Mitsubishi Chemical Corporation) and bisphenol F type epoxy resin (specifically, product number jER4004P manufactured by Mitsubishi Chemical Corporation). It is preferable to contain at least one kind.

  The epoxy equivalent of the epoxy resin is preferably 250 or more from the viewpoint of sufficiently suppressing the stickiness of the wet film formed from the resin composition for a solder resist and sufficiently improving the substrate adhesion of the solder resist layer. More preferably, it is 450 or more. Moreover, this epoxy equivalent is preferably 3300 or less, more preferably 2200 or less, from the viewpoint of imparting good photosensitivity to the solder resist resin composition.

  As the ethylenically unsaturated compound having a carboxyl group, a compound selected from appropriate polymers and prepolymers can be used. Specific examples of this compound include acrylic acid, methacrylic acid, crotonic acid, cinnamic acid, 2-acryloyloxyethyl succinic acid, 2-methacryloyloxyethyl succinic acid, 2-acryloyloxyethyl phthalic acid, 2-methacryloyloxyethyl phthalate. Acid, β-carboxyethyl acrylate, acryloyloxyethyl succinate, methacryloyloxyethyl succinate, 2-propenoic acid, 3- (2-carboxyethoxy) -3-oxypropyl ester, 2-acryloyloxyethyl tetrahydrophthalic acid 2-methacryloyloxyethyl tetrahydrophthalic acid, 2-acryloyloxyethyl hexahydrophthalic acid, 2-methacryloyloxyethyl hexahydrophthalic acid, ω-carboxy-polycaprolactone Compounds having only one ethylenically unsaturated group such as monoacrylate; pentaerythritol triacrylate, pentaerythritol trimethacrylate, trimethylolpropane diacrylate, trimethylolpropane dimethacrylate, dipentaerythritol pentaacrylate, dipentaerythritol pentamethacrylate Examples thereof include compounds having a plurality of ethylenically unsaturated groups, such as a compound obtained by reacting a dibasic acid anhydride with a polyfunctional acrylate having a hydroxyl group or the like and a polyfunctional methacrylate. These compounds are used individually by 1 type, or multiple types are used together. As the ethylenically unsaturated compound having a carboxyl group, acrylic acid is particularly preferable. In this case, the stickiness of the wet coating film formed from the resin composition for solder resist is sufficiently suppressed, and the plating resistance and solder heat resistance of the solder resist layer are improved.

  The total amount of the ethylenically unsaturated compound having a carboxyl group when the first photosensitive resin is synthesized is such that the carboxyl group of the ethylenically unsaturated compound having a carboxyl group is 1 mol of the epoxy group of the epoxy resin. The amount is preferably in the range of 0.7 to 1.2 mol, and particularly preferably the amount in which the carboxyl group is in the range of 0.9 to 1.1 mol. In this case, the residual amount of the epoxy group in the first photosensitive resin is particularly reduced, and therefore the resin composition for the solder resist when the resin composition for the solder resist is placed under weak heat drying conditions such as preliminary drying is used. The thermosetting reaction is suppressed, and therefore, a decrease in developability after exposure of the resin composition for solder resist is suppressed. Furthermore, the residual ethylenically unsaturated compound having an unreacted carboxyl group during the synthesis of the first photosensitive resin is suppressed.

  In this embodiment, the polybasic acid anhydride contains cyclohexane-1,2,4-tricarboxylic acid-1,2-anhydride represented by the above structural formula (1).

  The polybasic acid anhydride may contain a compound other than cyclohexane-1,2,4-tricarboxylic acid-1,2-anhydride represented by the above structural formula (1). For example, polybasic acid anhydrides are phthalic anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methyl nadic anhydride, hexahydrophthalic anhydride, methylhexahydrophthalic anhydride, succinic anhydride, methyl succinic anhydride, anhydrous Dibasic acid anhydrides such as maleic acid, citraconic anhydride, glutaric anhydride, itaconic anhydride; tribasic acids such as trimellitic anhydride, pyromellitic anhydride, benzophenone tetracarboxylic anhydride, methylcyclohexene tetracarboxylic anhydride One or more compounds selected from the group consisting of the above acid anhydrides and the like may be contained.

  The amount of cyclohexane-1,2,4-tricarboxylic acid-1,2-anhydride used in the structural formula (1) is not particularly limited, but is 15 to 100 mass with respect to the total amount of polybasic acid anhydride. % Is preferable.

  Moreover, it is preferable to adjust the usage-amount of a polybasic acid anhydride so that the acid value of the 1st photosensitive resin synthesize | combined may become the range of 30-160 mgKOH / g. When the acid value of the first photosensitive resin is 30 mgKOH / g or more, the adhesion between the solder resist layer and the substrate can be further improved. When the acid value of the first photosensitive resin is 160 mgKOH / g or less, the residual amount of carboxyl groups in the solder resist layer formed from the resin composition for solder resist is reduced, and the solder resist layer has good electrical properties. Characteristics are maintained. A more desirable range of the acid value of the first photosensitive resin is 60 to 130 mgKOH / g.

  When the first photosensitive resin is synthesized, the addition reaction between the epoxy resin and the ethylenically unsaturated compound having a carboxyl group and the addition reaction between the product resulting from this addition reaction and the polybasic acid anhydride are allowed to proceed. In doing so, a known method may be employed. For example, in the addition reaction between an epoxy resin and an ethylenically unsaturated compound having a carboxyl group, an ethylenically unsaturated compound having a carboxyl group is added to the solvent solution of the epoxy resin, and a thermal polymerization inhibitor and a catalyst are added as necessary. In addition, a reactive solution is obtained by stirring and mixing. 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., by a conventional method.

  Examples of the solvent used in the addition reaction include aromatic hydrocarbons such as toluene, xylene, and tetramethylbenzene; ethylene glycol monoethyl ether, ethylene glycol monomethyl ether, ethylene glycol monobutyl ether, diethylene glycol monoethyl ether, diethylene glycol monomethyl Glycol ethers such as ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, dipropylene glycol diethyl ether, triethylene glycol monoethyl ether; ethyl acetate, butyl acetate, ethylene glycol monoethyl ether acetate, ethylene glycol Monobutyl ether acetate, diethylene glycol Monoethyl ether acetate, diethylene glycol monobutyl ether acetate, acetic acid esters such as propylene glycol monomethyl ether acetate. Of these organic solvents, only one type may be used, or two or more types may be used in combination.

  Examples of the thermal polymerization inhibitor include, but are not limited to, hydroquinone, methyl hydroquinone, hydroquinone monomethyl ether, catechol, pyrogallol, phenothiazine, and the like. Of these thermal polymerization inhibitors, only one kind may be used, or two or more kinds may be used in combination.

  Examples of the catalyst include tertiary amines such as triethylamine, quaternary ammonium salts such as triethylbenzylammonium chloride, imidazole compounds such as 2-ethyl-4-methylimidazole, and phosphorus compounds such as triphenylphosphine. However, it is not limited to these. Of these catalysts, only one type may be used, or two or more types may be used in combination.

  In proceeding the addition reaction between the addition reaction product and the polybasic acid anhydride, the polybasic acid anhydride is added to the solvent solution of the addition reaction product, and a thermal polymerization inhibitor and a catalyst are added as necessary. A reactive solution is obtained by stirring and mixing. The first photosensitive resin is obtained by reacting this reactive solution by a conventional method. The reaction conditions may be the same as in the addition reaction between the epoxy resin and the ethylenically unsaturated compound. As the solvent, the thermal polymerization inhibitor, and the catalyst, the compounds used in the addition reaction between the epoxy resin and the ethylenically unsaturated compound having a carboxyl group can be used as they are.

  The first photosensitive resin obtained as described above preferably has a weight average molecular weight in the range of 800 to 50,000. When the weight average molecular weight of the first photosensitive resin is in the range of 800 to 50,000, particularly excellent photosensitivity and resolution are imparted to the resin composition for solder resist. The weight average molecular weight is a value (polystyrene conversion) measured by gel permeation chromatography.

  Thus, the epoxy resin used for synthesizing the first photosensitive resin is a bifunctional epoxy resin, and the polybasic acid anhydride is a compound having a structure represented by the above structural formula (1). Thus, the tackiness of the dried coating film formed from the resin composition for a solder resist containing the first photosensitive resin is reduced, and the adhesion between the solder resist layer obtained by curing this and the substrate is improved. At the same time, a solder resist layer having high characteristics such as alkali developability, electroless gold plating resistance, PCT resistance, and electrical insulation can be formed. This is considered to be because a crosslinking point decreases by using a bifunctional epoxy resin. Thereby, the tackiness of the dried coating film is reduced, and when the dried coating film is cured, excessive curing shrinkage can be suppressed, and flexibility can be imparted to the solder resist layer. As a result, the adhesion of the solder resist layer to the substrate is improved, and at the same time, the characteristics of the solder resist layer, such as electroless gold plating resistance, PCT resistance, and electrical insulation, are improved. The acid anhydride having the structure represented by the structural formula (1) originally has a carboxyl group, and 1 equivalent of a hydroxyl group is allowed to react with 1 equivalent of a compound having the structure represented by the structural formula (1). As a result, 2 equivalents of a carboxyl group can be obtained. Since the carboxyl group obtained by this reaction is in a position different from the position of the carboxyl group obtained by reacting an acid anhydride that does not originally have a carboxyl group, a solder resist having excellent alkali developability. A layer is obtained. In addition, the carboxyl group position is improved by changing the position of the carboxyl group. As a result, a solder resist layer having excellent properties such as adhesion to the substrate, electroless gold plating resistance, PCT resistance, and electrical insulation can be obtained. It is thought that it is obtained.

  In this embodiment, the resin composition for a solder resist further includes a photosensitive resin other than the first photosensitive resin (hereinafter referred to as a second photosensitive resin) together with the first photosensitive resin. It is preferable to contain.

  Examples of the second photosensitive resin include a resin having a structure in which an ethylenically unsaturated compound having a carboxyl group is added to a polyfunctional epoxy resin and a polyvalent carboxylic acid component is further added. The polyvalent carboxylic acid component is a component composed of one or more compounds selected from the group consisting of polyvalent carboxylic acids and acid anhydrides thereof.

  The epoxy resin that can be used to synthesize the second photosensitive resin, the ethylenically unsaturated compound having a carboxyl group, and the polyvalent carboxylic acid component will be described in more detail.

  The epoxy resin for synthesizing the second photosensitive resin is preferably one having three or more epoxy groups in one molecule. Examples of the epoxy resin include phenol novolac type epoxy resins, cresol novolac type epoxy resins, biphenyl novolac type epoxy resins, bisphenol A-novolac type epoxy resins, and the like.

  The epoxy resin for synthesizing the second photosensitive resin may be a polymer of an ethylenically unsaturated compound including a compound having an epoxy group. Even if only the compound which has an epoxy group is used as an ethylenically unsaturated compound, the compound which has an epoxy group, and the compound which does not have an epoxy group may be used together.

  Examples of the compound having an epoxy group include an appropriate polymer or prepolymer. Specific examples of the compound having an epoxy group include epoxycyclohexyl derivatives of acrylic acid or methacrylic acid; alicyclic epoxy derivatives of acrylate or methacrylate; β-methylglycidyl acrylate, β-methylglycidyl methacrylate, and the like. Among these compounds, only one type may be used, or two or more types may be used in combination.

  The compound which does not have an epoxy group should just be a compound copolymerizable with the compound which has the epoxy group used simultaneously. Specific examples of compounds having no epoxy group include benzyl (meth) acrylate, neopentylglycol benzoate (meth) acrylate, paracumylphenoxyethylene glycol (meth) acrylate, EO-modified cresol (meth) acrylate, ethoxylated phenyl (meth) ) Acrylate, nonylphenoxypolyethylene glycol (meth) acrylate (degree of polymerization n = 2 to 17), ECH-modified phenoxy (meth) acrylate, phenoxydiethylene glycol (meth) acrylate, phenoxyethyl (meth) acrylate, phenoxyhexaethylene glycol (meth) Acrylate, phenoxytetraethylene glycol (meth) acrylate, tribromophenyl (meth) acrylate, EO-modified tribromophenyl (medium ) Acrylate, EO modified bisphenol A di (meth) acrylate, PO modified bisphenol A di (meth) 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, vinylcarbazole, styrene, N-phenylmaleimide, N-benzylmaleimide, 3-maleimidobenzoic acid N-succinimidyl, linear or branched aliphatic or alicyclic (however, (May have some unsaturated bonds in the ring) (meth) acrylic acid ester, hydroxyalkyl (meth) acrylate, alkoxyalkyl (meth) acrylate, etc .; N-substituted males such as N-cyclohexylmaleimide Bromide, and the like can be mentioned. Along with these compounds, if necessary, ethylene in one molecule such as polyethylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, etc. A compound having two or more polymerizable unsaturated groups may be used in combination. Among these compounds, only one type may be used, or two or more types may be used in combination. These compounds are preferable in that the hardness and oiliness of the solder resist layer can be easily adjusted.

  The ethylenically unsaturated compound reacts by a known polymerization method such as solution polymerization or emulsion polymerization. Examples of the solution polymerization method include a method in which an ethylenically unsaturated compound is heated and stirred in a suitable organic solvent in the presence of a polymerization initiator in a nitrogen atmosphere, and an azeotropic polymerization method.

  Examples of organic solvents used for the polymerization of ethylenically unsaturated compounds include ketones such as methyl ethyl ketone and cyclohexanone, and aromatic hydrocarbons such as toluene and xylene, and ethyl acetate, butyl acetate, cellosolve acetate, and butyl cellosolve. Examples include acetates such as acetate, butyl carbitol acetate, and propylene glycol monomethyl ether acetate, and dialkyl glycol ethers. Among these organic solvents, only one kind may be used, or two or more kinds may be used in combination.

  Examples of polymerization initiators used for the polymerization of ethylenically unsaturated compounds include 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 peroxides such as t-butyl peroxybivalate; And peroxydicarbonates such as diisopropyl peroxydicarbonate; azo compounds such as azobisisobutyronitrile. Among these polymerization initiators, only one type may be used, or two or more types may be used in combination. In addition, a redox initiator may be used as the polymerization initiator.

  As the ethylenically unsaturated compound having a carboxyl group for synthesizing the second photosensitive resin, an appropriate polymer or prepolymer may be mentioned. Specific examples of the ethylenically unsaturated compound include acrylic acid, methacrylic acid, crotonic acid, cinnamic acid, 2-acryloyloxyethyl succinic acid, 2-methacryloyloxyethyl succinic acid, 2-acryloyloxyethyl phthalic acid, 2- Methacryloyloxyethyl phthalic acid, β-carboxyethyl acrylate, acryloyloxyethyl succinate, methacryloyloxyethyl succinate, 2-propenoic acid, 3- (2-carboxyethoxy) -3-oxypropyl ester, 2-acryloyloxy Ethylenic acid such as ethyltetrahydrophthalic acid, 2-methacryloyloxyethyltetrahydrophthalic acid, 2-acryloyloxyethylhexahydrophthalic acid, 2-methacryloyloxyethylhexahydrophthalic acid, etc. Compounds having KazuHajime only one can be cited. As this ethylenically unsaturated compound, a polyfunctional acrylate having a hydroxyl group such as pentaerythritol triacrylate, pentaerythritol trimethacrylate, trimethylolpropane diacrylate, trimethylolpropane dimethacrylate, dipentaerythritol pentaacrylate, dipentaerythritol pentamethacrylate, etc. And compounds having a plurality of ethylenically unsaturated groups, such as compounds obtained by reacting dibasic acid anhydrides with polyfunctional methacrylates. These compounds are used individually by 1 type, or multiple types are used together. The ethylenically unsaturated compound having a carboxyl group preferably contains at least one of acrylic acid and methacrylic acid. In this case, since the ethylenically unsaturated group introduced into the second photosensitive resin by acrylic acid and methacrylic acid is particularly excellent in photoreactivity, the photoreactivity of the second photosensitive resin is increased.

  The amount of the ethylenically unsaturated compound used in the synthesis of the second photosensitive resin 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. It is preferable that the amount is such that the carboxyl group is in the range of 0.5 to 1.1 mol.

  The polyvalent carboxylic acid component for synthesizing the second photosensitive resin includes phthalic acid, tetrahydrophthalic acid, methyltetrahydrophthalic acid, methylnadic acid, hexahydrophthalic acid, methylhexahydrophthalic acid, succinic acid, methylsuccinic acid. Dicarboxylic acids such as acid, maleic acid, citraconic acid, glutaric acid and itaconic acid; polybasic carboxylic acids having three or more basic acids such as trimellitic acid, pyromellitic acid, benzophenone tetracarboxylic acid, methylcyclohexene tetracarboxylic acid, and the like And acid anhydrides of polyvalent carboxylic acids. Among these compounds, only one type may be used, or two or more types may be used in combination.

  The amount of the polyvalent carboxylic acid component used is adjusted so that the acid value of the second photosensitive resin is preferably 30 mgKOH / g or more, particularly preferably 60 mgKOH / g or more. The amount of the polyvalent carboxylic acid component used is adjusted so that the acid value of the second photosensitive resin is preferably 160 mgKOH / g or less, particularly preferably 130 mgKOH / g or less.

  When the second photosensitive resin is synthesized, the addition reaction between the epoxy compound and the ethylenically unsaturated compound having a carboxyl group and the addition reaction between the product of the addition reaction and the polyvalent carboxylic acid component are allowed to proceed. In this case, a known method, for example, a method similar to the case where the first photosensitive resin is synthesized can be employed.

  The weight average molecular weight of the second photosensitive resin is not particularly limited, but the preferred range is 800 to 100,000. Within this range, particularly excellent photosensitivity and resolution are imparted to the solder resist resin composition.

  As described above, when the solder resist resin composition contains the first photosensitive resin and the second photosensitive resin, the tackiness of the dry coating film formed from the solder resist resin composition is reduced. Further, it is possible to more effectively form a solder resist layer that can maintain other properties at the same time while improving the adhesion to the substrate. This is because the first photosensitive resin and the second photosensitive resin are used in combination, so that the cured state after UV irradiation and heat treatment of the solder resist has an appropriate crosslinking density. Presumed to be obtained.

  The ratio of the first photosensitive resin and the second photosensitive resin in the solder resist resin composition is not particularly limited, but the first photosensitive resin and the second photosensitive resin with respect to the total amount of the first photosensitive resin and the second photosensitive resin. It is preferable that the ratio of the photosensitive resin is 20 to 80% by mass. In this case, the solder resist layer formed from the resin composition for solder resists has excellent heat resistance, and can improve the adhesion between the solder resist layer and the substrate. As a result, a solder resist layer having excellent characteristics such as electroless gold plating resistance, PCT resistance, and electrical insulation can be obtained.

  In this embodiment, it is preferable that the resin composition for solder resist further contains an epoxy compound having at least two epoxy groups in one molecule. In this case, thermosetting can be imparted to the resin composition for solder resist. This epoxy compound may be a poorly solvent-soluble epoxy compound or a general-purpose solvent-soluble epoxy compound. The type of the epoxy compound is not particularly limited, and in particular, a phenol novolac type epoxy resin (specifically, product number EPICLON N-775 manufactured by DIC Corporation) and a cresol novolac type epoxy resin (specific example, product number EPICLON N- manufactured by DIC Corporation). 695), bisphenol A type epoxy resin (part number jER1001 manufactured by Mitsubishi Chemical Corporation as a specific example), bisphenol A-novolak type epoxy resin (part number EPICLON N-865 manufactured by DIC Corporation as a specific example), bisphenol F type epoxy resin (Part number jER4004P manufactured by Mitsubishi Chemical Corporation as a specific example), Bisphenol S type epoxy resin (Part number EPICLON EXA-1514 manufactured by DIC Corporation as a specific example), Bisphenol AD type epoxy resin, Biff Nyl type epoxy resin (specifically, product number YX4000 manufactured by Mitsubishi Chemical Corporation), biphenyl aralkyl type epoxy resin (specifically, product number NC-3000 manufactured by Nippon Kayaku Co., Ltd.), hydrogenated bisphenol A type epoxy resin (specific example) As a product number ST-4000D manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.), naphthalene type epoxy resin (specific examples: product numbers EPICLON HP-4032, EPICLON HP-4700, EPICLON HP-4770 manufactured by DIC Corporation), special bifunctional type epoxy resin (As specific examples, product numbers YL7175-500 and YL7175-1000 manufactured by Mitsubishi Chemical Corporation; product numbers EPICLON TSR-960, EPICLON TER-601, EPICLON TSR-250-80BX, EPICL manufactured by DIC Corporation) ON 1650-75MPX, 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 other bisphenol-based epoxy resins are preferable. Triglycidyl isocyanurate preferably contains a β-form having a structure in which three epoxy groups are bonded to the S-triazine ring skeleton surface in the same direction. Even if triglycidyl isocyanurate contains the β-form described above and an α-form having a structure in which one epoxy group is bonded to the other two epoxy groups in a different direction with respect to the S-triazine ring skeleton surface. Good.

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

  The ratio of the epoxy compound in the solder resist resin composition is not particularly limited, but the ratio of the total amount of the epoxy compound is preferably 0.1% by mass or more based on the total solid content of the resin composition for the solder resist. In this case, the solder resistance, plating resistance, etc. of the solder resist layer are further improved. Moreover, if this ratio is 50 mass% or less, the developability of the resin composition for solder resist will further improve.

  In this embodiment, it is preferable that the resin composition for solder resist contains a photopolymerization initiator.

  Examples of the photopolymerization initiator include benzoin and its alkyl ethers; acetophenones such as acetophenone and benzyldimethyl ketal; anthraquinones such as 2-methylanthraquinone; 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2 -Thioxanthones such as isopropylthioxanthone, 4-isopropylthioxanthone, 2,4-diisopropylthioxanthone; benzophenones such as benzophenone and 4-benzoyl-4'-methyldiphenyl sulfide; xanthones such as 2,4-diisopropylxanthone; Α-hydroxy ketones such as hydroxy-2-methyl-1-phenyl-propan-1-one; 2-methyl-1- [4- (methylthio) phenyl] -2-morpholino-1-propanone, etc. Compounds containing nitrogen atoms; 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide (Lucirin TPO), 2,4,6-trimethylbenzoyl-ethyl-phenyl-phosphinate (SPEEDCURE TPO-L), bis ( Acylphosphine oxides such as 2,4,6-trimethylbenzoyl) -phenylphosphine oxide (Irgacure 819), bis (2,6-dimethoxybenzoyl) -2,4,4-trimethyl-pentylphosphine oxide (CGI 403) And photopolymerization initiators. Along with the photopolymerization initiator, known photopolymerization accelerators and sensitizers such as tertiary amines such as p-dimethylbenzoic acid ethyl ester, p-dimethylaminobenzoic acid isoamyl ester, 2-dimethylaminoethylbenzoate, etc. May be used. Photopolymerization initiators for visible light exposure and near infrared exposure are also used as necessary. Of these photopolymerization initiators, only one kind may be used, or two or more kinds may be used in combination. In addition to a photopolymerization initiator, a coumarin derivative such as 7-diethylamino-4-methylcoumarin, other carbocyanine dyes, xanthene dyes, etc. may be used in combination as a sensitizer for laser exposure.

  When the photopolymerization initiator contains an acylphosphine oxide photopolymerization initiator, it is also preferred that the photopolymerization initiator further contains α-hydroxyacetophenone. α-Hydroxyacetophenone is less susceptible to oxygen damage than acylphosphine oxide photopolymerization initiators and is less likely to discolor due to heat. For this reason, when (alpha) -hydroxy acetophenone is used, the sclerosis | hardenability of the surface layer at the time of exposure of the resin composition for solder resists becomes high especially. Specific examples of α-hydroxyacetophenone include 1-hydroxy-cyclohexyl-phenyl-ketone (Irgacure 184), 2-hydroxy-2-methyl-1-phenyl-propan-1-one (Darocur 1173), 1- [4. -(2-hydroxyethoxy) -phenyl] -2-hydroxy-2-methyl-1-propan-1-one (Irgacure 2959), 2-hydroxy-1- {4- [4- (2-hydroxy-2-) Methyl-propionyl) -benzyl] -phenyl} -2-methyl-propan-1-one (Irgacure 127).

  When the resin composition for a solder resist contains an acylphosphine oxide photopolymerization initiator and α-hydroxyacetophenone, the content of the acylphosphine oxide photopolymerization initiator is in the range of 0.1 to 20% by mass, The content of α-hydroxyacetophenone is preferably in the range of 0.1 to 20% by mass. In this case, the photocurability of the resin composition for a solder resist is sufficiently maintained, the hardness of the solder resist layer is further improved, and the developer resistance of the solder resist layer is improved. For this reason, in particular, the electroless gold plating resistance of the solder resist layer is improved.

  The content of the photopolymerization initiator in the solder resist resin composition takes into account the balance between the photocurability of the solder resist resin composition and the physical properties of the solder resist layer formed from the solder resist resin composition. Therefore, it is preferably set appropriately, and particularly preferably in the range of 0.1 to 30% by mass with respect to the total solid content of the resin composition for solder resist.

  When the resin composition for solder resist contains a photopolymerization initiator, it is also preferable that the resin composition for solder resist further contains a photopolymerizable compound. The photopolymerizable compound is selected from monomers and prepolymers having photopolymerizability. This photopolymerizable compound is used, for example, for the purpose of dilution of the resin composition for solder resist, viscosity adjustment, acid value adjustment, photopolymerization adjustment and the like. Examples of the photopolymerizable compound include an appropriate polymer or prepolymer having photopolymerizability. Specific examples of the photopolymerizable compound include monofunctional (meth) acrylates such as 2-hydroxyethyl (meth) acrylate; diethylene glycol di (meth) acrylate, trimethylolpropane di (meth) acrylate, trimethylolpropane tri (meth) Multifunctional (such as acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, ε-caprolactone modified pentaerythritol hexaacrylate And (meth) acrylate. Among such compounds, only one kind may be used, or two or more kinds may be used in combination.

  It is also preferable that this photopolymerizable compound contains a phosphorus-containing compound (phosphorus-containing photopolymerizable compound). In this case, the flame retardancy of the solder resist layer is improved. Examples of phosphorus-containing photopolymerizable compounds include 2-methacryloyloxyethyl acid phosphate (specific examples: product numbers Light Ester P-1M and Light Ester P-2M manufactured by Kyoeisha Chemical Co., Ltd.), 2-acryloyloxyethyl acid phosphate. (As a specific example, product number light acrylate P-1A manufactured by Kyoeisha Chemical Co., Ltd.), diphenyl-2-methacryloyloxyethyl phosphate (as a specific example, product number MR-260 manufactured by Daihachi Kogyo Co., Ltd.), manufactured by Showa Polymer Co., Ltd. HFA series (part number HFA-6003, which is an addition reaction product of dipentaerystol hexaacrylate and HCA as a specific example, and part number HFA which is an addition reaction product of HFA-6007, caprolactone-modified dipentaerystol hexaacrylate and HCA) -3003 And HFA-6127 etc.) and the like.

  When a photopolymerizable compound is used, the content of the photopolymerizable compound in the solder resist resin composition may be in the range of 0.05 to 40% by mass with respect to the total amount of the solder resist resin composition. preferable. Furthermore, this content is desirably 50% by mass or less based on the total solid content of the resin composition for solder resist. When the content of the photopolymerizable compound is within such a range, it is suppressed that the surface adhesiveness of the dry coating film formed from the resin composition for solder resist becomes too strong.

  The resin composition for solder resists may contain an organic solvent as necessary. The organic solvent is used for the purpose of, for example, liquefaction or varnishing of the solder resist resin composition, viscosity adjustment, application property adjustment, film formation property adjustment, and the like. Specific examples of the organic solvent include linear, branched, secondary or polyhydric alcohols such as ethanol, propyl alcohol, isopropyl alcohol, hexanol and ethylene glycol; ketones such as methyl ethyl ketone and cyclohexanone; aroma such as toluene and xylene. Group hydrocarbons; petroleum-based aromatic mixed solvents such as Swazol series (manufactured by Maruzen Petrochemical Co., Ltd.) and Solvesso series (manufactured by Exxon Chemical Co.); cellosolves such as cellosolve and butylcellosolve; carbitol, butylcarbitol 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 Acetic esters; dialkyl glycol ethers and the like. Among these organic solvents, only one kind may be used, or two or more kinds may be used in combination.

  Content of the organic solvent in the resin composition for solder resists is set suitably. This content is preferably adjusted so that the organic solvent is volatilized quickly when the coating film formed from the resin composition for solder resist is temporarily dried, that is, the organic solvent does not remain in the dried coating film. . The content of the organic solvent is preferably in the range of 5 to 99.5% by mass with respect to the total amount of the solder resist resin composition, and in this case, the good coatability of the solder resist resin composition is maintained. Is done. In addition, since suitable content of an organic solvent changes with the apply | coating methods etc., it is preferable that content is adjusted suitably according to the apply | coating method.

  In addition to the above-mentioned photosensitive resin and epoxy compound, the solder resist resin composition further includes, for example, tolylene diisocyanate, morpholine diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate-based blocked with caprolactam, oxime, malonate, etc. Thermosetting components such as isocyanate and melamine, n-butylated melamine resin, isobutylated melamine resin, butylated urea resin, butylated melamine urea cocondensation resin, benzoguanamine-based cocondensation resin; UV curable epoxy ( (Meth) acrylate; bisphenol A type, phenol novolac type, cresol novolac type, alicyclic epoxy resin, etc. added with (meth) acrylic acid; diallyl phthalate resin, phenoxy resin, Ramin resins, urethane resins, may contain such a polymer compound such as a fluorine resin.

  It is also preferable that the resin composition for solder resist contains a filler. Examples of the filler include inorganic fillers such as barium sulfate, crystalline silica, nano silica, titanium oxide, carbon nanotubes, talc, bentonite, aluminum hydroxide, and magnesium hydroxide. When such a filler is contained, curing shrinkage of the coating film formed from the resin composition for solder resist is reduced. The proportion of the filler in the solder resist resin composition is appropriately set, but is preferably in the range of 10 to 50% by mass. In this case, the proportion of the solid content of the solder resist resin composition increases, For this reason, the volume change at the time of the resin composition for solder resists being heat-dried is suppressed, For this reason, the crack tolerance of a solder resist layer further improves.

  The resin composition for a solder resist, if necessary, a curing agent that cures the epoxy compound; a curing accelerator; a colorant such as a pigment; a copolymer such as silicone or acrylate; a leveling agent; a silane coupling agent; Thioxotropic agent; Polymerization inhibitor; Antihalation agent; Flame retardant; Antifoaming agent; Antioxidant; Surfactant; Polymer dispersing agent;

[Preparation of resin composition for solder resist]
The resin composition for a solder resist can be prepared by blending the raw material components as described above and kneading by a known kneading method using, for example, a three-roll, ball mill, sand mill or the like. In that case, a part of each of the above components, for example, a part of the photopolymerizable compound and the organic solvent and the epoxy resin are mixed in advance and dispersed, and separately, the remaining components are mixed and dispersed in advance. The solder resist resin composition may be prepared by mixing both at the time of use.

[Formation of solder resist layer on printed wiring board]
A printed wiring board having a solder resist layer is produced by forming a solder resist layer on the printed wiring board. The method for forming the solder resist layer is not particularly limited.

  An example of a method for forming the solder resist layer is as follows.

After applying the resin composition for solder resist to the printed wiring board by an appropriate method such as dipping, spraying, spin coating, roll coating, curtain coating, screen printing, etc., the organic solvent in the resin composition for solder resist In order to volatilize, for example, preliminary drying is performed at 60 to 120 ° C. to form a dry coating film.
When forming a dry paint film on a printed wiring board, the resin composition for solder resist is applied to an appropriate support in advance and then dried to form a paint film (dry film). The dry film may be transferred onto the printed wiring board by applying pressure to the dry film and the printed wiring board after being stacked on the wiring board (dry film method). In this case, preliminary drying may be omitted.

  A negative mask on which a pattern is drawn is applied directly or indirectly to the surface of the dry coating film, and the active energy rays are irradiated to expose the dry coating film through the negative mask. As a negative mask, a photo tool 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 that transmits active energy rays and other portions are formed as non-exposed portions that shield active energy rays Etc. are used. Examples of the active energy ray include appropriate active energy rays such as ultraviolet rays, visible light, and near infrared rays depending on the composition of the resin composition for solder resist. For example, ultraviolet rays or the like are irradiated from a light source such as a chemical lamp, a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, an ultrahigh pressure mercury lamp, a xenon lamp, or a metal halide lamp.

  The exposure method is not limited to the method using a negative mask as described above, and an appropriate method can be adopted. For example, a direct drawing method using laser exposure or the like can also be adopted.

  By removing the negative mask from the printed wiring board after exposure and developing, the non-exposed portion of the dried coating film is removed, and a solder resist layer is formed on the exposed portion of the remaining dried coating film.

  In the development treatment, an appropriate developer according to the type of the solder resist resin composition for forming the photosensitive resin layer can be used. Specific examples of the developer include, for example, sodium carbonate aqueous solution, potassium carbonate aqueous solution, ammonium carbonate aqueous solution, sodium hydrogen carbonate aqueous solution, potassium hydrogen carbonate aqueous solution, ammonium hydrogen carbonate aqueous solution, sodium hydroxide aqueous solution, potassium hydroxide aqueous solution, ammonium hydroxide. Examples of the alkaline solution include an aqueous solution, a tetramethylammonium hydroxide aqueous solution, and a lithium hydroxide aqueous solution. In addition to the alkaline solution, organic amines such as monoethanolamine, diethanolamine, triethanolamine, monoisopropanolamine, diisopropanolamine, triisopropanolamine can be used, and these can be used alone or in combination. it can.

  Furthermore, when a solder resist layer contains an epoxy compound, the epoxy compound is thermally cured by subjecting the solder resist layer to heat treatment under conditions of, for example, 120 to 180 ° C. for about 30 to 90 minutes. In this case, the film strength, hardness, chemical resistance, etc. of the solder resist layer are improved.

  Further, if necessary, after the solder resist layer is subjected to heat treatment, the solder resist layer may be further irradiated with ultraviolet rays. 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.

  Thus, according to the present invention, while reducing the tackiness of the dried coating film and improving the adhesion to the substrate, at the same time, characteristics such as alkali developability, electroless gold plating resistance, PCT resistance, electrical insulation, etc. A resin composition for a solder resist that can form a solder resist layer that can be maintained at a high level is obtained.

[Synthesis Example A-1]
A four-necked flask equipped with a reflux condenser, a thermometer, an air blowing tube and a stirrer was charged with 472 parts by mass of a bisphenol A type epoxy resin (manufactured by Mitsubishi Chemical Corporation, product number jER1001, epoxy equivalent 472), diethylene glycol monoethyl ether acetate 202. A reaction solution was prepared by adding mass parts, 0.2 parts by mass of methylhydroquinone, 72 parts by mass of acrylic acid, and 3 parts by mass of triphenylphosphine. This reaction solution was heated at 115 ° C. for 12 hours while air was blown into the four-necked flask to cause the addition reaction to proceed. Subsequently, 118.9 parts by mass of cyclohexane-1,2,4-tricarboxylic acid-1,2-anhydride (Mitsubishi Gas Chemical Co., Ltd., product number H-TMAn-S) was added to the liquid in the four-necked flask, diethylene glycol. 158 mass parts of monoethyl ether acetate was added, and it was made to react by heating at 110 degreeC for 5 hours. This obtained the 65 mass% solution of photosensitive resin. The solution of the photosensitive resin thus obtained had an acid value of 101 mgKOH / g. Moreover, the weight average molecular weight of the photosensitive resin was 2675.

[Synthesis Example A-2]
A four-necked flask equipped with a reflux condenser, a thermometer, an air blowing tube, and a stirrer was equipped with 919 parts by weight of bisphenol A type epoxy resin (manufactured by Mitsubishi Chemical Corporation, product number jER1004, epoxy equivalent 919), diethylene glycol monoethyl ether acetate 394. A reaction solution was prepared by adding mass parts, 0.2 parts by mass of methylhydroquinone, 72 parts by mass of acrylic acid, and 3 parts by mass of triphenylphosphine. This reaction solution was heated at 115 ° C. for 12 hours while air was blown into the four-necked flask to cause the addition reaction to proceed. Subsequently, 213.8 parts by mass of cyclohexane-1,2,4-tricarboxylic acid-1,2-anhydride (Mitsubishi Gas Chemical Co., Ltd., product number H-TMAn-S) was added to the liquid in the four-necked flask. 257 parts by mass of diethylene glycol monoethyl ether acetate was added and reacted by heating at 110 ° C. for 5 hours. This obtained the 65 mass% solution of photosensitive resin. The solution of the photosensitive resin thus obtained had an acid value of 100 mgKOH / g. Moreover, the weight average molecular weight of the photosensitive resin was 8630.

[Synthesis Example A-3]
A four-necked flask equipped with a reflux condenser, a thermometer, an air blowing tube, and a stirrer was mixed with 884 parts by mass of bisphenol F type epoxy resin (manufactured by Mitsubishi Chemical Corporation, product number jER4004P, epoxy equivalent 884), diethylene glycol monoethyl ether acetate 379. A reaction solution was prepared by adding mass parts, 0.2 parts by mass of methylhydroquinone, 72 parts by mass of acrylic acid, and 3 parts by mass of triphenylphosphine. This reaction solution was heated at 115 ° C. for 12 hours while air was blown into the four-necked flask to cause the addition reaction to proceed. Subsequently, 202 parts by mass of cyclohexane-1,2,4-tricarboxylic acid-1,2-anhydride (manufactured by Mitsubishi Gas Chemical Co., Ltd., product number H-TMAn-S) was added to the liquid in the four-necked flask, diethylene glycol mono 246 mass parts of ethyl ether acetate was added, and it was made to react by heating at 110 degreeC for 5 hours. This obtained the 65 mass% solution of photosensitive resin. The solution of the photosensitive resin thus obtained had an acid value of 99 mgKOH / g. Moreover, the weight average molecular weight of the photosensitive resin was 8123.

[Synthesis Example A-4]
A four-necked flask equipped with a reflux condenser, a thermometer, an air blowing tube and a stirrer was charged with 472 parts by mass of a bisphenol A type epoxy resin (manufactured by Mitsubishi Chemical Corporation, product number jER1001, epoxy equivalent 472), diethylene glycol monoethyl ether acetate 202. A reaction solution was prepared by adding mass parts, 0.2 parts by mass of methylhydroquinone, 72 parts by mass of acrylic acid, and 3 parts by mass of triphenylphosphine. This reaction solution was heated at 115 ° C. for 12 hours while air was blown into the four-necked flask to cause the addition reaction to proceed. Subsequently, 79.2 parts by mass of cyclohexane-1,2,4-tricarboxylic acid-1,2-anhydride (manufactured by Mitsubishi Gas Chemical Co., Ltd., product number H-TMAn-S) was added to the liquid in the four-necked flask. Tetrahydrophthalic anhydride (60.8 parts by mass) and diethylene glycol monoethyl ether acetate (168 parts by mass) were added and reacted by heating at 110 ° C. for 5 hours. This obtained the 65 mass% solution of photosensitive resin. The solution of the photosensitive resin thus obtained had an acid value of 98 mgKOH / g. The weight average molecular weight of the photosensitive resin was 2513.

[Synthesis Example A-5]
A four-necked flask equipped with a reflux condenser, a thermometer, an air blowing tube and a stirrer was charged with 472 parts by mass of a bisphenol A type epoxy resin (manufactured by Mitsubishi Chemical Corporation, product number jER1001, epoxy equivalent 472), diethylene glycol monoethyl ether acetate 202. Parts by weight, 0.2 parts by weight of methylhydroquinone, 64.8 parts by weight of acrylic acid, ω-carboxy-polycaprolactone (n≈2) monoacrylate (manufactured by Toagosei Co., Ltd., trade name Aronix M-5300, number average molecular weight 290) ) A reaction solution was prepared by adding 32 parts by mass and 3 parts by mass of triphenylphosphine. This reaction solution was heated at 115 ° C. for 12 hours while air was blown into the four-necked flask to cause the addition reaction to proceed. Subsequently, 118.9 parts by mass of cyclohexane-1,2,4-tricarboxylic acid-1,2-anhydride (Mitsubishi Gas Chemical Co., Ltd., product number H-TMAn-S) was added to the liquid in the four-necked flask. 170 mass parts of diethylene glycol monoethyl ether acetate was added, and it was made to react by heating at 110 degreeC for 5 hours. This obtained the 65 mass% solution of photosensitive resin. The solution of the photosensitive resin thus obtained had an acid value of 98 mgKOH / g. The weight average molecular weight of the photosensitive resin was 3241.

[Synthesis Example B-1]
A four-necked flask equipped with a reflux condenser, a thermometer, an air blowing tube and a stirrer, 203 parts by mass of cresol novolac epoxy resin (manufactured by Nippon Steel & Sumikin Chemical Co., Ltd., product number YDCN-700-5, epoxy equivalent 203), diethylene glycol The addition reaction was allowed to proceed by adding 103 parts by mass of monoethyl ether acetate, 0.2 parts by mass of methylhydroquinone, 72 parts by mass of acrylic acid, and 1.5 parts by mass of triphenylphosphine and heating at 110 ° C. for 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 liquid in the four-necked flask and reacted by heating at 80 ° C. for 3 hours. This obtained the 65 mass% solution of photosensitive resin. The weight average molecular weight of the photosensitive resin was 6605.

[Synthesis Example B-2]
A four-necked flask equipped with a reflux condenser, a thermometer, an air blowing tube and a stirrer, 203 parts by mass of cresol novolac epoxy resin (manufactured by Nippon Steel & Sumikin Chemical Co., Ltd., product number YDCN-700-5, epoxy equivalent 203), diethylene glycol 105 parts by mass of monoethyl ether acetate, 0.2 part by mass of methylhydroquinone, 43.2 parts by mass of acrylic acid, and 3 parts by mass of triphenylphosphine were added and reacted at 100 ° C. for 3 hours. Then, 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 and reacted by heating at 110 ° C. for 6 hours. This obtained the 65 mass% solution of photosensitive resin. The weight average molecular weight of the photosensitive resin was 5,852.

[Synthesis Example C-1]
A four-necked flask equipped with a reflux condenser, a thermometer, an air blowing tube, and a stirrer was equipped with 919 parts by weight of bisphenol A type epoxy resin (manufactured by Mitsubishi Chemical Corporation, product number jER1004, epoxy equivalent 919), diethylene glycol monoethyl ether acetate 394. A reaction solution was prepared by adding mass parts, 0.2 parts by mass of methylhydroquinone, 72 parts by mass of acrylic acid, and 3 parts by mass of triphenylphosphine. This reaction solution was heated at 115 ° C. for 12 hours while air was blown into the four-necked flask to cause the addition reaction to proceed. Subsequently, 380 parts by mass of tetrahydrophthalic anhydride and 346 parts by mass of diethylene glycol monoethyl ether acetate were added to the liquid in the four-necked flask and reacted by heating at 110 ° C. for 5 hours. This obtained the 65 mass% solution of photosensitive resin. The solution of the photosensitive resin thus obtained had an acid value of 102 mgKOH / g. The weight average molecular weight of the photosensitive resin was 8489.

[Synthesis Example C-2]
A four-necked flask equipped with a reflux condenser, a thermometer, an air blowing tube, and a stirrer was equipped with 919 parts by weight of bisphenol A type epoxy resin (manufactured by Mitsubishi Chemical Corporation, product number jER1004, epoxy equivalent 919), diethylene glycol monoethyl ether acetate 394. A reaction solution was prepared by adding mass parts, 0.2 parts by mass of methylhydroquinone, 72 parts by mass of acrylic acid, and 3 parts by mass of triphenylphosphine. This reaction solution was heated at 115 ° C. for 12 hours while air was blown into the four-necked flask to cause the addition reaction to proceed. Subsequently, 220 parts by mass of succinic anhydride and 260 parts by mass of diethylene glycol monoethyl ether acetate were added to the liquid in the four-necked flask and reacted by heating at 110 ° C. for 5 hours. This obtained the 65 mass% solution of photosensitive resin. The solution of the photosensitive resin thus obtained had an acid value of 102 mgKOH / g. The weight average molecular weight of the photosensitive resin was 8365.

[Preparation of resin composition for solder resist]
In each Example and Comparative Example, a resin composition for a solder resist was obtained by kneading a mixture obtained by blending the raw materials shown in Table 1 with three rolls.

[Evaluation test]
(Production of test pieces in Examples 1 to 9 and Comparative Examples 1 to 3)
A glass epoxy base copper clad laminate provided with a 35 μm thick copper foil was prepared. A printed wiring board was obtained by forming a conductor pattern by etching the glass epoxy base copper clad laminate. A wet paint film was formed on the entire surface of the printed wiring board by applying the resin composition for a solder resist according to each example and comparative example on the surface of the printed wiring board by screen printing. This wet paint film was heated at 80 ° C. for 40 minutes and preliminarily dried to form a dry paint film having a thickness of 20 μm. The dry coating film was selectively exposed by directly applying a negative mask on the surface of the dry coating film and irradiating with the optimum exposure amount of ultraviolet rays in each solder resist resin composition. The exposed dried coating film was subjected to a development treatment using an aqueous sodium carbonate solution, so that a portion (cured film) cured by exposure in the dried coating film was left on the printed wiring board. This cured film was further heated and cured at 150 ° C. for 60 minutes. Subsequently, the cured film was irradiated with 1000 mJ / cm ² of ultraviolet rays. Thereby, the solder resist layer was formed on the printed wiring board, and the test piece provided with the solder resist layer was obtained.

  The following evaluation tests were performed on these solder resist layers.

(Developability)
Development was performed with a 1 mass percent aqueous sodium carbonate solution for 90 seconds at a spray pressure of 0.2 MPa, and evaluation was performed according to the following evaluation criteria.
A: The break point (time required for developing the dried coating film) is 0 to 30 seconds, and there is no portion that is not developed.
B: The break point is 31 to 60 seconds, and there is no portion that is not developed.
C: The break point is 61 to 90 seconds, and there is no portion that is not developed.
D: There is a portion that is not developed.

(Tackiness)
During test piece production, the state of adhesion of the dried coating film when the negative mask was removed during exposure was evaluated according to the following evaluation criteria.
A: When the negative mask was removed, no peeling resistance was felt, and there was no sticking mark on the dry film.
B: Adhesion was not felt when the negative mask was removed, but a slight sticking mark of the mask was observed on the dry film.
C: A slight peeling resistance was felt when removing the negative mask, and a mask mark was observed on the dried film.
D: It was difficult to remove the negative mask, and the mask pattern was damaged when it was forcibly removed.

(Adhesion)
According to the test method of JIS D0202, a cross cut of 100 squares was put in a grid pattern on the solder resist layer of the test piece, and then the state of peeling after the peeling test with a cellophane adhesive tape was visually observed. The results were evaluated according to the following evaluation criteria.
A: Cross cut residual ratio is 91 to 100%.
B: Cross cut residual ratio is 81 to 90%.
C: Cross cut residual ratio is 61 to 80%.
D: Cross cut residual ratio is 60% or less.

(Pencil hardness)
The pencil hardness of the solder resist layer in the test piece was measured and evaluated according to JIS K5400 using Mitsubishi High Uni (manufactured by Mitsubishi Pencil Co., Ltd.).

(Acid resistance)
After immersing the test piece in a 10% aqueous sulfuric acid solution at room temperature for 30 minutes, the appearance of the solder resist layer was visually observed. The results were evaluated according to the following evaluation criteria.
A: No abnormality occurs.
B: A slight change is observed.
C: A little change is seen.
D: A large change such as peeling is seen on the coating film.

(Alkali resistance)
After immersing the test piece in a 10% aqueous sodium hydroxide solution at room temperature for 1 hour, the appearance of the solder resist layer was visually observed. The results were evaluated according to the following evaluation criteria.
A: No abnormality occurs.
B: A slight change is observed.
C: A little change is seen.
D: A large change such as peeling is seen on the coating film.

(Solder heat resistance)
LONCO 3355-11 (water-soluble flux manufactured by London Chemical Co., Ltd.) was used as the flux. First, the flux was applied to the test piece, and then immersed in a molten solder bath at 260 ° C. for 10 seconds, and then washed with water. The appearance of the solder resist layer after performing this cycle three times was observed. The results were evaluated according to the following evaluation criteria.
A: No abnormality occurs.
B: A slight change is observed.
C: A little change is seen.
D: A large change such as peeling is seen in the solder resist layer.

(Plating resistance)
The test piece was plated using a commercially available electroless nickel plating bath and electroless gold plating bath, and the state of plating was observed. Moreover, the adhesion state of the solder resist layer after plating was observed by performing a cellophane adhesive tape peeling test on the solder resist layer. The results were evaluated according to the following evaluation criteria.
A: There is no change in appearance, no peeling at the time of tape peeling, and no penetration of plating.
B: There is no change in appearance, and peeling does not occur even when the tape is peeled off.
C: Although there is no change in appearance, partial peeling is observed at the time of tape peeling.
D: The solder resist layer is lifted and peeling is observed when the tape is peeled off.

(PCT resistance)
After leaving the test piece in saturated steam at a temperature of 121 ° C. for 50 hours, the appearance of the solder resist layer of this test piece was observed. The results were evaluated according to the following evaluation criteria.
A: No change such as blistering, peeling or discoloration is observed.
B: Slight changes such as blistering, peeling, and discoloration are observed.
C: Some changes such as blistering, peeling, and discoloration are observed.
D: Changes such as blistering, peeling, and discoloration are observed.

(Electrical insulation)
A printed wiring board for evaluation was obtained by forming a comb-type electrode having a line width / space width of 100 μm / 100 μm on the copper-clad laminate (FR-4). On this printed wiring board, a solder resist layer was formed by the same method and conditions as in the case of producing a test piece. Subsequently, while applying a DC 12 V bias voltage to the comb-shaped electrode, the printed wiring board was placed at 121 ° C. and 97% R.D. H. The test environment was exposed for 200 hours. The electrical resistance value of the solder resist layer in this test environment was constantly measured. The results were evaluated according to the following evaluation criteria.
A: The electric resistance value was constantly maintained at 10 ⁶ Ω or more until 200 hours passed from the start of the test.
B: Although the elapsed time from the start of the test was 150 hours or more and less than 200 hours and the electric resistance value was less than 10 ⁶ Ω, the electric resistance value was maintained at 10 ⁶ Ω or more until then.
C: The elapsed time from the start of the test was 100 hours or more and less than 150 hours, and the electric resistance value was less than 10 ⁶ Ω. Until then, the electric resistance value was maintained at 10 ⁶ Ω or more.
D: The elapsed time from the start of the test was less than 100 hours, and the electrical resistance value was less than 10 ⁶ Ω.

(Test results)
The results of the above evaluation tests are shown in Table 1 below.

The details of the components in the table are as follows.
Epoxy compound A: biphenyl type epoxy resin, manufactured by Mitsubishi Chemical Corporation, product number YX4000.
Epoxy compound B: Cresol novolac type epoxy resin, manufactured by DIC Corporation, product number EPICLON N-695.
Photopolymerization initiator A: 2,4,6-trimethylbenzoyldiphenylphosphine oxide, manufactured by BASF, product number Lucirin TPO.
Photopolymerization initiator B: 1-hydroxy-cyclohexyl-phenyl-ketone, manufactured by Ciba Japan Co., Ltd., product number Irgacure 184.
Photopolymerizable compound: dipentaerythritol hexaacrylate, manufactured by Nippon Kayaku Co., Ltd., product number KAYARAD DPHA.
Melamine resin: Nissan Chemical Industries, Ltd., product number melamine HM.
Barium sulfate: manufactured by Sakai Chemical Industry Co., Ltd., product number Variace B30.
Bentonite: manufactured by Leox, part number Benton SD-2.
Antifoaming agent: Simethicone (mixture of dimethicone and silicic acid), manufactured by Shin-Etsu Silicone Co., Ltd., product number KS-66.
Organic solvent: diethylene glycol monoethyl ether acetate.

Claims (3)

Containing a first photosensitive resin and a second photosensitive resin;
The first photosensitive resin has a structure in which an ethylenically unsaturated compound having a carboxyl group is added to an epoxy resin, and a polybasic acid anhydride is further added.
The epoxy resin is a bifunctional epoxy resin;
The polybasic acid anhydride contains a compound having a structure represented by the following structural formula (1) ,

The second photosensitive resin has a structure in which an ethylenically unsaturated compound having a carboxyl group is added to an epoxy resin having three or more epoxy groups in one molecule, and a polyvalent carboxylic acid component is further added. ,
Resin composition for solder resist . The resin composition for a solder resist according to claim 1, wherein the ratio of the first photosensitive resin to the total amount of the first photosensitive resin and the second photosensitive resin is 20 to 80% by mass. . The resin composition for a solder resist according to claim 1 or 2 , wherein the bifunctional epoxy resin contains at least one selected from a bisphenol A type epoxy resin and a bisphenol F type epoxy resin.