WO2023190454A1

WO2023190454A1 - Photosensitive resin composition and printed wiring board production method

Info

Publication number: WO2023190454A1
Application number: PCT/JP2023/012393
Authority: WO
Inventors: 大作須藤; 晋一朗福田; 大地岡本; 優之志村
Original assignee: 太陽ホールディングス株式会社
Priority date: 2022-03-29
Filing date: 2023-03-28
Publication date: 2023-10-05
Also published as: KR20240155931A

Abstract

[Problem] To provide a photosensitive resin composition having preferable characteristics required during printed wiring board production, wherein crystallization of a component is suppressed even when exposed to an environment under which an ordinary temperature condition and a low temperature condition are repeated. [Solution] This photosensitive resin composition comprises a carboxy group-containing resin, a photopolymerization initiator, and an organic solvent, wherein an α-aminoacetophenone-based photopolymerization initiator is blended as the photopolymerization initiator, and a petroleum-based solvent, a carbitol acetate, and dipropylene glycol monomethyl ether are blended as the organic solvent.

Description

Photosensitive resin composition and printed wiring board manufacturing method

The present invention relates to a photosensitive resin composition, and particularly to a photosensitive resin composition suitably used for forming a solder resist layer. Furthermore, the present invention also relates to a method for manufacturing a printed wiring board including a cured product formed using the photosensitive resin composition.

As electronic devices have become lighter, thinner, shorter, and more sophisticated in recent years, there is an increasing need for higher density and higher precision component mounting on printed wiring boards that make up electronic devices. To meet such needs, today solder resist layers are patterned by coating a photosensitive resin composition on a substrate, drying, and curing, and then applying the patterned photosensitive resin composition to the substrate. The mainstream is to use a so-called photo solder resist that is fully cured by heating or light irradiation.

On the other hand, the photosensitive resin composition for forming the solder resist layer is generally placed under various environments from its manufacture to its actual use, and in many cases, it is only placed in a normal temperature environment around room temperature. They may be exposed to environments that alternate between room temperature and low temperature environments.

Normally, photosensitive resin compositions are adjusted to maintain sufficient storage stability at room temperature, but when exposed to environments that alternate between room temperature and low temperature environments, the photosensitive resin composition The composition and properties of the resin composition may be impaired. If the composition or properties of the photosensitive resin composition are impaired, there is a problem that the formed solder resist layer will not exhibit sufficient performance. In particular, as mentioned above, in the production of printed wiring boards in which components are mounted with high density and high precision, it is necessary to form a precise and highly reliable solder resist layer. Changes in the composition and properties of substances can be a major problem. Therefore, in many cases, photosensitive resin compositions are required not only to have storage stability in a room temperature environment but also to have storage stability in an environment that alternates between a room temperature environment and a low temperature environment. In response to such demands, for example, by further reacting a polybasic acid anhydride with a reaction product of a polynuclear epoxy compound having a specific structure and an unsaturated group-containing monocarboxylic acid, the temperature environment can be changed. It has also been proposed to provide a photosensitive resin composition with excellent stability (for example, Patent Document 1).

However, there are various environments in which photosensitive resin compositions are placed, and different environments cause different problems. Improving this remains an ongoing technical challenge.

Japanese Patent Application Publication No. 2001-278947

When a photosensitive resin composition is exposed to an environment that alternates between room temperature and low temperature environments, some of its components may crystallize, impairing the original composition and homogeneity of the photosensitive resin composition. As a result, there is a problem that the solder resist layer that is formed does not exhibit sufficient performance.

Therefore, an object of the present invention is to provide a photosensitive material that suppresses the crystallization of components even when exposed to an environment that repeats a room temperature environment and a low temperature environment, and that has good characteristics required in the production of printed wiring boards. It is an object of the present invention to provide a resin composition with high compatibility. Another object of the present invention is to provide a method for manufacturing a printed wiring board comprising a cured product formed using a photosensitive resin composition having the above-mentioned favorable properties.
Means to solve problems

As a result of intensive research, the present inventors have found that in a photosensitive resin composition containing a carboxyl group-containing resin, a photopolymerization initiator, and an organic solvent, an α-aminoacetophenone photopolymerization initiator is blended as a photopolymerization initiator, It was also found that the above-mentioned problems can be solved by blending petroleum solvents, carbitol acetates, and dipropylene glycol monomethyl ether as organic solvents. The present invention is based on this knowledge. That is, the gist of the present invention is as follows.

[1] A photosensitive resin composition containing a carboxyl group-containing resin, a photopolymerization initiator, and an organic solvent,
The photopolymerization initiator includes an α-aminoacetophenone photopolymerization initiator,
A photosensitive resin composition, wherein the organic solvent contains a petroleum solvent, carbitol acetates, and dipropylene glycol monomethyl ether.
[2] The photosensitive resin composition according to [1], wherein the organic solvent has a mass ratio of petroleum solvent to carbitol acetate of 1:0.5 to 1:1.
[3] The photosensitive resin composition according to [1], wherein the organic solvent has a mass ratio of petroleum solvent to dipropylene glycol monomethyl ether of 1:0.7 to 1:1.2.
[4] The photosensitive material according to [1], wherein the total content of the petroleum solvent, carbitol acetate, and dipropylene glycol monomethyl ether is 50 to 90 parts by mass based on 100 parts by mass of the carboxyl group-containing resin. resin composition.
[5] The α-aminoacetophenone photopolymerization initiator contains 2-dimethylamino-2-(4-methylbenzyl)-1-(4-morpholin-4-yl-phenyl)-butan-1-one. , the photosensitive resin composition according to [1].
[6] The photosensitive resin composition according to [1], which is used for forming a solder resist layer.
[7] A method for manufacturing a printed wiring board including a solder resist layer, the method comprising the step of forming the solder resist layer by curing the photosensitive resin composition according to [1].

According to the present invention, the crystallization of the components is suppressed even when exposed to an environment that repeats a room temperature environment and a low temperature environment, and the photosensitive resin has various favorable properties required in the production of printed wiring boards. A composition can be provided. Furthermore, according to the present invention, it is possible to provide a method for manufacturing a printed wiring board including a cured product formed using a photosensitive resin composition having the above-mentioned favorable properties.

[Photosensitive resin composition]
The photosensitive resin composition of the present invention contains a carboxyl group-containing resin, a photopolymerization initiator, and an organic solvent as essential components, the photopolymerization initiator contains an α-aminoacetophenone photopolymerization initiator, and the organic solvent contains petroleum It is characterized by containing a system solvent, carbitol acetates, and dipropylene glycol monomethyl ether. The photosensitive resin composition of the present invention is formulated by combining a specific photopolymerization initiator and a specific organic solvent, so that the photosensitive resin composition can be exposed to an environment that repeatedly changes between a room temperature environment and a low temperature environment. Even in the case of cycling (hereinafter also referred to as "cold/hot cycle"), crystallization of components such as a photopolymerization initiator can be suppressed. That is, an α-aminoacetophenone photopolymerization initiator is blended into a photosensitive resin composition as a photopolymerization initiator, and at least three types of organic solvents, including petroleum solvents, carbitol acetates, and dipropylene glycol monomethyl ether, are added. By blending, the above-mentioned excellent effects can be achieved. As a result, the photosensitive resin composition of the present invention maintains its composition and properties even when used after cooling and heating cycles, and can have various favorable properties required during the production of printed wiring boards. In addition, the occurrence of crystals in photosensitive resin compositions may cause pinholes, repelling, clogging of printing plates, etc. during printing, and may also cause unevenness on the surface of the cured product (solder resist layer). As a result, there is a possibility that the yield of the photosensitive resin composition itself, a cured product obtained using the photosensitive resin composition, and a printed wiring board including the cured product may be reduced. Therefore, it can be said that the photosensitive resin composition of the present invention can also solve these problems by suppressing the crystallization after the above-mentioned cooling/heating cycle.
Each component of the photosensitive resin composition of the present invention will be explained in detail below.

(Carboxyl group-containing resin)
In the photosensitive resin composition of the present invention, various conventionally known resins having a carboxyl group in the molecule can be used as the carboxyl group-containing resin. When the photosensitive resin composition contains a carboxyl group-containing resin, alkaline developability can be imparted to the photosensitive resin composition. In particular, from the viewpoint of photocurability and development resistance, carboxyl group-containing resins having ethylenically unsaturated double bonds in the molecule are preferred. The ethylenically unsaturated double bond in the molecule is preferably derived from acrylic acid or methacrylic acid or derivatives thereof. One type of carboxyl group-containing resin may be used alone, or two or more types may be used in combination. In addition, when using only carboxyl group-containing resins that do not have ethylenically unsaturated double bonds as carboxyl group-containing resins, compounds having multiple ethylenically unsaturated groups in the molecule as described below, that is, photopolymerizable By using a monomer in combination, the photosensitive resin composition is made photocurable. Specific examples of carboxyl group-containing resins include the following compounds (which may be oligomers or polymers). In this specification, "(meth)acrylate" is a term that collectively refers to acrylate, methacrylate, and mixtures thereof, and includes other similar expressions such as "(meth)acrylic acid" and "(meth)acryloyl." The same applies to

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

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

(3) Diisocyanate and bifunctional epoxy resins such as bisphenol A epoxy resin, hydrogenated bisphenol A epoxy resin, bisphenol F epoxy resin, bisphenol S epoxy resin, bixylenol epoxy resin, and biphenol epoxy resin ( Carboxyl group-containing photosensitivity resulting from polyaddition reaction of partially acid anhydride-modified products of reactants with monocarboxylic acid compounds having ethylenically unsaturated double bonds such as meth)acrylic acid, carboxyl group-containing dialcohol compounds, and diol compounds. Urethane resin.

(4) During the synthesis of the resin in (2) or (3) above, a compound having one hydroxyl group and one or more (meth)acryloyl groups in the molecule, such as hydroxyalkyl (meth)acrylate, is added to the terminal (Meth)acrylated carboxyl group-containing photosensitive urethane resin.

(5) During the synthesis of the resin of (2) or (3) above, one isocyanate group and one or more (meth)acryloyl groups in the molecule of an equimolar reaction product of isophorone diisocyanate and pentaerythritol triacrylate, etc. A carboxyl group-containing photosensitive urethane resin that has been terminally (meth)acrylated by adding a compound having the following.

(6) A carboxyl group-containing photosensitive resin obtained by reacting (meth)acrylic acid with a bifunctional or higher polyfunctional (solid) epoxy resin and adding a dibasic acid anhydride to the hydroxyl group present in the side chain.

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

(8) Difunctional oxetane resin is reacted with a dicarboxylic acid such as adipic acid, phthalic acid, hexahydrophthalic acid, etc., and the resulting primary hydroxyl group is converted into a dibase such as phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, etc. Carboxyl group-containing polyester resin with acid anhydride added.

(9) An epoxy compound having multiple epoxy groups in one molecule, a compound having at least one alcoholic hydroxyl group and one phenolic hydroxyl group in one molecule, such as p-hydroxyphenethyl alcohol, and (meth) Maleic anhydride, tetrahydrophthalic anhydride, trimellitic anhydride, pyromellitic anhydride, adipine are reacted with an unsaturated group-containing monocarboxylic acid such as acrylic acid, and the alcoholic hydroxyl group of the resulting reaction product is A carboxyl group-containing photosensitive resin obtained by reacting polybasic acid anhydrides such as acids.

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

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

(12) A carboxyl group-containing photosensitive resin obtained by adding a compound having one epoxy group and one or more (meth)acryloyl groups in one molecule to the resins (1) to (11) described above.

The acid value of the carboxyl group-containing resin is preferably 30 to 150 mgKOH/g, more preferably 50 to 120 mgKOH/g. When the acid value of the carboxyl group-containing resin is 30 mgKOH/g or more, the alkali developability of the photosensitive resin composition becomes good. Further, by having an acid value of 150 mgKOH/g or less, it is possible to easily draw a good resist pattern.

The weight average molecular weight of the carboxyl group-containing resin varies depending on the resin skeleton, but is generally preferably from 2,000 to 150,000, more preferably from 5,000 to 100,000. When the weight average molecular weight is 2,000 or more, tack-free performance and resolution can be improved. Further, by having a weight average molecular weight of 150,000 or less, the developability and storage stability of the photosensitive resin composition can be improved.

The content of the carboxyl group-containing resin in the photosensitive resin composition is preferably 10 to 40% by mass, more preferably 20 to 35% by mass in terms of solid content. When the content of the carboxyl group-containing resin is 10% by mass or more, the strength of the coating film can be improved. Moreover, when the content of the carboxyl group-containing resin is 40% by mass or less, the viscosity of the photosensitive resin composition becomes appropriate, and processability improves.

(Photopolymerizable monomer)
A photopolymerizable monomer can be added to the photosensitive resin composition of the present invention, if necessary. The photopolymerizable monomer is a monomer having an ethylenically unsaturated double bond. Examples of such photopolymerizable monomers include commonly known polyester (meth)acrylates, polyether (meth)acrylates, urethane (meth)acrylates, carbonate (meth)acrylates, and epoxy (meth)acrylates. Specifically, alkyl acrylates such as 2-ethylhexyl acrylate and cyclohexyl acrylate; hydroxyalkyl acrylates such as 2-hydroxyethyl acrylate and 2-hydroxypropyl acrylate; alkylenes such as ethylene glycol, propylene glycol, diethylene glycol, and dipropylene glycol; Mono- or diacrylates of oxide derivatives; acrylamides such as N,N-dimethylacrylamide, N-methylolacrylamide, N,N-dimethylaminopropylacrylamide; N,N-dimethylaminoethyl acrylate, N,N-dimethylaminopropyl Aminoalkyl acrylates such as acrylate; polyhydric alcohols such as hexanediol, trimethylolpropane, pentaerythritol, ditrimethylolpropane, dipentaerythritol, trishydroxyethyl isocyanurate, or their alkylene oxide adducts or ε-caprolactone adducts, etc. polyhydric acrylates; phenols such as phenoxy acrylate and bisphenol A diacrylate, or polyhydric acrylates such as alkylene oxide adducts thereof; glycidyls such as glycerin diglycidyl ether, trimethylolpropane triglycidyl ether, triglycidyl isocyanurate, etc. Ether acrylates; not limited to the above, acrylates and melamine acrylates obtained by directly acrylating polyols such as polyether polyols, polycarbonate diols, hydroxyl-terminated polybutadienes, and polyester polyols, or converting them into urethane acrylates via diisocyanates, and the above-mentioned acrylates. It is possible to appropriately select and use at least one kind of methacrylates corresponding to the above. Such photopolymerizable monomers can also be used as reactive diluents. The photopolymerizable monomers may be used alone or in combination of two or more.

The content of the photopolymerizable monomer in the photosensitive resin composition is preferably 10 to 100 parts by weight based on 100 parts by weight of the carboxyl group-containing resin. When the content of the photopolymerizable monomer is 10 parts by mass or more, the photosensitive resin composition has good photocurability, and pattern formation becomes easy in alkaline development after irradiation with active energy rays. On the other hand, when the content of the photopolymerizable monomer is 100 parts by mass or less, halation is less likely to occur and good resolution can be obtained.

When using a non-photosensitive carboxyl group-containing resin that does not have ethylenically unsaturated double bonds as the above-mentioned carboxyl group-containing resin, the photopolymerizable monomer is used in order to make the photosensitive resin composition photocurable. This is effective because it requires the use of a polymerizable monomer.

(Photopolymerization initiator)
In the photosensitive resin composition of the present invention, the photopolymerization initiator includes an α-aminoacetophenone photopolymerization initiator. Any known α-acetaminophenone photopolymerization initiator can be used. Specific examples of α-acetaminophenone photopolymerization initiators include 2-dimethylamino-2-(4-methylbenzyl)-1-(4-morpholin-4-yl-phenyl)-butane-1 -one, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholino-1-propanone, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butan-1-one , 2-(dimethylamino)-2-[(4-methylphenyl)methyl]-1-[4-(4-morpholinyl)phenyl]-1-butanone, N,N-dimethylaminoacetophenone, etc. . One type of α-aminoacetophenone photopolymerization initiator may be used alone, or two or more types may be used in combination.

The photosensitive resin composition contains, as a photopolymerization initiator, an α-aminoacetophenone photopolymerization initiator having a structure in which a strong electron-donating group such as an alkylthio group or a dialkylamino group is substituted at the para position of a benzoyl group. Accordingly, high curability can be obtained.

The photosensitive resin composition may contain an additional photopolymerization initiator (hereinafter also referred to as "other photopolymerization initiator") in addition to the above-mentioned α-aminoacetophenone photopolymerization initiator. Other photopolymerization initiators include hydroxyacetophenone photopolymerization initiators, acylphosphine oxide photopolymerization initiators, benzoin alkyl ether photopolymerization initiators, benzophenone photopolymerization initiators, acetophenone photopolymerization initiators, Examples include thioxanthone photopolymerization initiators, anthraquinone photopolymerization initiators, ketal photopolymerization initiators, benzoic acid ester photopolymerization initiators, oxime ester photopolymerization initiators, titanocene photopolymerization initiators, etc. . Other photopolymerization initiators may be used alone or in combination of two or more.

The photopolymerization initiator preferably contains only an α-aminoacetophenone photopolymerization initiator. Further, as the α-aminoacetophenone photopolymerization initiator, preferably 2-dimethylamino-2-(4-methyl-benzyl)-1-(4-morpholin-4-yl-phenyl)-butane-1- On is used. As a commercially available α-aminoacetophenone photopolymerization initiator, for example, Omnirad (registered trademark) 907 (2-methyl-1-[4-(methoxythio)phenyl]-2-morpholinopropane-1 manufactured by IGM Resins) -one), 369 (2-benzyl-2-(dimethylamino)-4'-morpholinobutyrophenone), 369E (2-benzyl-2-(dimethylamino)-4'-morpholinobutyrophenone), 379 (2- dimethylamino-2-(4-methyl-benzyl)-1-(4-morpholin-4-yl-phenyl)-butan-1-one) and the like.

The content of the photopolymerization initiator in the photosensitive resin composition is preferably 1 to 1 to 100 parts by mass of the carboxyl group-containing resin in terms of solid content. The amount is 20 parts by weight, more preferably 5 to 15 parts by weight. When the photopolymerization initiator contains the other photopolymerization initiators mentioned above, and the other photopolymerization initiators are photopolymerization initiators other than oxime ester photopolymerization initiators, other photopolymerization initiators in the photosensitive resin composition The content of the polymerization initiator is preferably 1 to 20 parts by weight, more preferably 5 to 15 parts by weight, based on 100 parts by weight of the carboxyl group-containing resin, in terms of solid content. In addition, when the photopolymerization initiator contains the other photopolymerization initiator mentioned above and the other photopolymerization initiator is an oxime ester photopolymerization initiator, the oxime ester photopolymerization initiator in the photosensitive resin composition The content is preferably 0.01 to 5 parts by weight, more preferably 0.1 to 5 parts by weight, based on 100 parts by weight of the carboxyl group-containing resin, in terms of solid content. By having the content of the α-aminoacetophenone photopolymerization initiator and other photopolymerization initiators within the above-mentioned ranges, the photosensitive resin composition has good photocurability, and has good peeling resistance, heat resistance, and The coating properties such as chemical properties are also improved, and the effect of reducing outgassing is obtained.Furthermore, the light absorption on the surface of the solder resist coating is improved, and deep curability is less likely to deteriorate. Furthermore, since the content of each photopolymerization initiator is within the above-mentioned range, the photopolymerization initiator is sufficiently dissolved in the organic solvent, so that crystallization of the photopolymerization initiator can be suppressed even under cooling/heating cycles. As a result, even when the photosensitive resin composition of the present invention is used after a cooling/heating cycle, its composition and properties are maintained, and it can have various good properties required during the production of printed wiring boards.

In the photosensitive resin composition of the present invention, a photoinitiation aid or a sensitizer may be used in combination with the above-mentioned photopolymerization initiator. Examples of the photoinitiation aid or sensitizer include benzoin compounds, acetophenone compounds, anthraquinone compounds, thioxanthone compounds, ketal compounds, benzophenone compounds, tertiary amine compounds, and xanthone compounds. From the viewpoint of deep curability of the cured product of the photosensitive resin composition, a thioxanthone compound and a tertiary amine compound are preferably used as the photoinitiation aid or sensitizer, and a thioxanthone compound is more preferably used. The above-mentioned photoinitiation aids and sensitizers may be used alone or in combination of two or more.

(thermosetting component)
The photosensitive resin composition of the present invention may contain a thermosetting component, if necessary. The thermosetting components used in the present invention include known and commonly used components such as isocyanate compounds, blocked isocyanate compounds, amino resins, maleimide compounds, benzoxazine resins, carbodiimide resins, cyclocarbonate compounds, epoxy compounds, oxetane compounds, and episulfide resins. can be mentioned. The thermosetting components may be used alone or in combination of two or more. Among these, the preferred thermosetting component is epoxy resin.

Examples of the epoxy resin include bisphenol A epoxy resin, bisphenol F epoxy resin, hydrogenated bisphenol A epoxy resin, brominated bisphenol A epoxy resin, bisphenol S epoxy resin, novolac epoxy resin, and phenol novolac epoxy resin. Resin, cresol novolac type epoxy resin, bisphenol A novolac type epoxy resin, biphenyl type epoxy resin, naphthalene type epoxy resin, dicyclopentadiene type epoxy resin, triphenylmethane type epoxy resin, glycidylamine type epoxy resin, alicyclic epoxy resin resin, trihydroxyphenylmethane type epoxy resin, bixylenol type or biphenol type epoxy resin, tetraphenylolethane type epoxy resin, heterocyclic epoxy resin, diglycidyl phthalate resin, tetraglycidyl xylenoylethane resin, glycidyl methacrylate resin Examples include polymerized epoxy resins, copolymerized epoxy resins of cyclohexylmaleimide and glycidyl methacrylate, and CTBN-modified epoxy resins.

Commercially available epoxy resins include, for example, jER (registered trademark) 828, 834, 1001, 1004 manufactured by Mitsubishi Chemical Corporation, and EPICLON (registered trademark) 840, 850, 850-S, 1050, 2055 manufactured by DIC Corporation. , Epotote (registered trademark) YD-011, YD-013, YD-127, YD-128 manufactured by Nippon Steel Chemical & Materials Co., Ltd., D. E. R. (Trademark) 317, 331, 661, 664, bisphenol A type epoxy resins such as Sumi-Epoxy ESA-011, ESA-014, ELA-115, ELA-128 manufactured by Sumitomo Chemical; jERYL903, DIC manufactured by Mitsubishi Chemical Corporation EPICLON 152 and 165 manufactured by Nippon Steel Chemical & Materials, EPOTOTE YDB-400 and YDB-500 manufactured by Nippon Steel Chemical & Materials, and D. E. R. 542, Sumiepoxy (registered trademark) ESB-400, ESB-700 manufactured by Sumitomo Chemical Co., Ltd.; jER (registered trademark) 152, 154 manufactured by Mitsubishi Chemical Corporation, D. E. N. (Trademark) 431, 438, EPICLON (registered trademark) N-730, N-770, N-865 manufactured by DIC Corporation, EPOTOTE (registered trademark) YDCN-701, YDCN-704 manufactured by Nippon Steel Chemical & Materials Co., Ltd. , EPPN-201, EOCN-1025, EOCN-1020, EOCN-104S, RE-306, NC-3000 manufactured by Nippon Kayaku Co., Ltd., Sumiepoxy (registered trademark) ESCN-195X, ESCN-220 manufactured by Sumitomo Chemical Co., Ltd. , YDCN-700-2, YDCN-700-3, YDCN-700-5, YDCN-700-7, YDCN-700-10, YDCN-704, YDCN-704A, manufactured by Nippon Steel Chemical & Materials Co., Ltd., DIC stock. Novolac type epoxy resins such as EPICLON (registered trademark) N-680, N-690, N-695 manufactured by the company; EPICLON (registered trademark) 830 manufactured by DIC Corporation, jER (registered trademark) 807 manufactured by Mitsubishi Chemical Corporation , Bisphenol F type epoxy resins such as Epototh (registered trademark) YDF-170, YDF-175, YDF-2004 manufactured by Nippon Steel Chemical & Materials Co., Ltd.; Epototh (registered trademark) ST- manufactured by Nippon Steel Chemical & Materials Co., Ltd. Hydrogenated bisphenol A type epoxy resins such as 2004, ST-2007, ST-3000, YX8034 manufactured by Mitsubishi Chemical Corporation; jER (registered trademark) 604 manufactured by Mitsubishi Chemical Corporation, Epotote manufactured by Nippon Steel Chemical & Materials Corporation (registered trademark) YH-434, glycidylamine type epoxy resin such as Sumiepoxy (registered trademark) ELM-120 manufactured by Sumitomo Chemical Co., Ltd.; hydantoin type epoxy resin; Celloxide (registered trademark) 2021 manufactured by Daicel Corporation, Epolead (registered) Trademark) Alicyclic epoxy resins such as PB3600; trihydroxyphenylmethane type epoxy resins such as YL-933 manufactured by Mitsubishi Chemical Corporation, EPPN-501 and EPPN-502 manufactured by Nippon Kayaku Co., Ltd.; manufactured by Mitsubishi Chemical Corporation Bixylenol type or biphenol type epoxy resin such as YL-6056, YX-4000, YL-6121 or a mixture thereof; EBPS-200 manufactured by Nippon Kayaku Co., Ltd., EPX-30 manufactured by ADEKA Co., Ltd., manufactured by DIC Corporation Bisphenol S type epoxy resin such as EXA-1514; Bisphenol A novolac type epoxy resin such as jER (registered trademark) 157S manufactured by Mitsubishi Chemical Corporation; Tetra such as jER (registered trademark) YL-931 manufactured by Mitsubishi Chemical Corporation Phenylolethane type epoxy resin; Heterocyclic epoxy resin such as TEPIC (registered trademark) manufactured by Nissan Chemical Co., Ltd.; Diglycidyl phthalate resin such as Bremmer (registered trademark) DGT manufactured by NOF Corporation; Nippon Steel Chemical & Materials Tetraglycidylxylenoylethane resin such as ZX-1063 manufactured by Nippon Steel Chemical & Materials Co., Ltd.; ESN-190, ESN-360 manufactured by Nippon Steel Chemical & Materials Co., Ltd.; HP-4032, EXA-4750, EXA-4700 manufactured by DIC Corporation naphthalene type epoxy resins such as; dicyclopentadiene type epoxy resins such as HP-7200 and HP-7200H manufactured by DIC Corporation; glycidyl methacrylate copolymer epoxy resins such as CP-50S and CP-50M manufactured by NOF Corporation Resins; further examples include copolymerized epoxy resins of cyclohexylmaleimide and glycidyl methacrylate; CTBN-modified epoxy resins (eg, YR-102, YR-450, manufactured by Nippon Steel Chemical & Materials Co., Ltd.), and the like.

The content of the thermosetting component in the photosensitive resin composition is preferably such that the number of functional groups in the reacting thermosetting component is 0.3 to 3.0 mol per mol of carboxyl group contained in the above-mentioned carboxyl group-containing resin. , more preferably 0.5 to 2.5 mol.

In particular, when an epoxy resin is used as a thermosetting component, the equivalent of the epoxy group of the epoxy resin in the photosensitive resin composition is 0.3 per equivalent of the carboxyl group of the carboxyl group-containing resin in terms of solid content. It is preferably 3.0 to 3.0. By setting the epoxy group of the epoxy resin to 0.3 equivalent or more, it is possible to prevent carboxyl groups from remaining in the cured film and obtain good heat resistance, alkali resistance, electrical insulation, etc. On the other hand, by controlling the epoxy group of the epoxy resin to 3.0 equivalents or less, it is possible to prevent low molecular weight cyclic (thio)ether groups from remaining in the dried coating film and ensure good strength etc. of the cured coating. be able to.

(Thermosetting catalyst)
A thermosetting catalyst can be added to the photosensitive resin composition of the present invention, if necessary. Examples of the thermosetting catalyst used in the present invention include imidazole, 2-methylimidazole, 2-ethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 4-phenylimidazole, 1-cyanoethyl-2- Imidazole derivatives such as phenylimidazole, 1-(2-cyanoethyl)-2-ethyl-4-methylimidazole; dicyandiamide, benzyldimethylamine, 4-(dimethylamino)-N,N-dimethylbenzylamine, 4-methoxy-N , N-dimethylbenzylamine, 4-methyl-N,N-dimethylbenzylamine, hydrazine compounds such as adipic acid dihydrazide, sebacic acid dihydrazide, and phosphorus compounds such as triphenylphosphine. Commercially available thermosetting catalysts include, for example, 2MZ-A, 2MZ-OK, 2PHZ, 2P4BHZ, and 2P4MHZ (all brand names of imidazole compounds) manufactured by Shikoku Kasei Kogyo Co., Ltd., and U-CAT manufactured by San-Apro Co., Ltd. 3513N (trade name of a dimethylamine compound), DBU, DBN, U-CAT SA (registered trademark) 102 (all bicyclic amidine compounds and salts thereof), and the like. The thermosetting catalyst is not particularly limited to these, and may be any thermosetting catalyst for epoxy resins or oxetane compounds, or any catalyst that promotes the reaction of at least one of epoxy groups and oxetanyl groups with carboxyl groups. Also, guanamine, acetoguanamine, benzoguanamine, melamine, 2,4-diamino-6-methacryloyloxyethyl-S-triazine, 2-vinyl-2,4-diamino-S-triazine, 2-vinyl-4,6-diamino S-triazine derivatives such as -S-triazine/isocyanuric acid adduct and 2,4-diamino-6-methacryloyloxyethyl-S-triazine/isocyanuric acid adduct can also be used, and preferably these adhesion imparting agents include Compounds that also function are used in conjunction with thermosetting catalysts. One type of thermosetting catalyst may be used alone, or two or more types may be used in combination.

The content of the thermosetting catalyst in the photosensitive resin composition is preferably 0.1 to 20 parts by weight, more preferably 0.5 to 15 parts by weight, based on 100 parts by weight of the carboxyl group-containing resin. When the content of the thermosetting catalyst is 0.1 parts by mass or more, the cured product of the photosensitive resin composition has excellent heat resistance. On the other hand, when the content of the thermosetting catalyst is 20 parts by mass or less, the storage stability of the photosensitive resin composition is improved.

(Organic solvent)
The photosensitive resin composition of the present invention contains a petroleum solvent, carbitol acetates, and dipropylene glycol monomethyl ether as an organic solvent. The petroleum solvents, carbitol acetates, and dipropylene glycol monomethyl ether may be used alone or in combination of two or more. By using a combination of these three types of organic solvents, the components of the photosensitive resin composition can be sufficiently dissolved and the components can be prevented from crystallizing even under a cooling/heating cycle where the components are exposed to environments that alternate between room temperature and low temperature environments. This makes it possible to suppress precipitation. As a result, the composition and properties of the photosensitive resin composition can be maintained, and the photosensitive resin composition can have various favorable properties required for manufacturing printed wiring boards. Crystallization of the components of the photosensitive resin composition can be suppressed by using a combination of the three types of organic solvents described above. The reason why crystallization of the components can be suppressed even under cooling/heating cycles by using a combination of the three types of organic solvents described above is not clear, but it can be inferred as follows. That is, when using the three types of organic solvents contained in the photosensitive resin composition, petroleum solvents, carbitol acetates, and dipropylene glycol monomethyl ether, the change in solubility with respect to temperature changes is small (gradual). It is thought that the components of the photosensitive resin composition can be stably dissolved in these organic solvents even under cooling/heating cycles, so that crystallization of the components under cooling/heating cycles can be suppressed. On the other hand, even if the solvent has a higher solubility at room temperature than the three organic solvents mentioned above, if the solubility changes significantly (suddenly) with temperature changes, the photosensitivity under cooling/heating cycles may decrease. Since the dissolved state of the components of the resin composition is unstable, as a result, it may not be possible to sufficiently suppress the crystallization of the components under cooling/heating cycles.

In this specification, the petroleum solvent specifically refers to a hydrocarbon solvent containing an aromatic hydrocarbon or a mixture thereof derived from petroleum, such as petroleum ether, petroleum naphtha, hydrogenated petroleum naphtha, and solvent naphtha. The boiling point of the petroleum solvent is not particularly limited, and may be, for example, 150 to 200°C. The number of carbon atoms in the petroleum solvent is also not particularly limited, and examples include carbon numbers of 10 or more. In addition, aromatic hydrocarbons having 10 or more carbon atoms include, for example, aromatic compounds such as benzene, naphthalene, anthracene, etc., in which one or more hydrogen atoms are, for example, an alkyl group such as a methyl group, an ethyl group, a propyl group, a butyl group, etc. , or may be formed by substitution with an alkylene group such as an ethylene group, a propylene group, or a tetramethylene group.

Examples of aromatic hydrocarbons contained in petroleum solvents include benzene, naphthalene, anthracene, isopropylbenzene, n-propylbenzene, 1-methyl-3-ethylbenzene, 1-methyl-4-ethylbenzene, 1,3,5 -Trimethylbenzene, 1-methyl-2-ethylbenzene, t-butylbenzene, 1,2,4-trimethylbenzene, isobutylbenzene, s-butylbenzene, 1-methyl-3-isopropylbenzene, 1,2,3-trimethyl Benzene, 1-methyl-4-isopropylbenzene, indane, 1-methyl-2-isopropylbenzene, 1,3-diethylbenzene, 1-methyl-3-propylbenzene, n-butylbenzene, 1-methyl-4-propylbenzene , 1,2-diethylbenzene, 1,4-diethylbenzene, 1,3-dimethyl-5-ethylbenzene, 1-methyl-2-propylbenzene, 1,4-dimethyl-2-ethylbenzene, 2-methylindane, 1-methyl Indane, 1,2-dimethyl-4-ethylbenzene, 1,3-dimethyl-2-ethylbenzene, 1,2-dimethyl-3-ethylbenzene, 4-methylindane, 5-methylindane, 1,2,3,4- Tetramethylbenzene, 1,3-dimethyl-4-ethylbenzene, 1,2,4,5-tetramethylbenzene, 1,2,3,5-tetramethylbenzene, tetralin, 1-methylnaphthalene, 2-methylnaphthalene, etc. can be mentioned. The petroleum solvent may contain one or more types of aromatic hydrocarbons alone, or may contain two or more types in combination.

Commercially available petroleum solvents include, for example, Ipsol (registered trademark) #100 and #150 manufactured by Idemitsu Kosan Co., Ltd., T-SOL (trademark) 100 and 150 manufactured by ENEOS Corporation, and Cactus Solvent P-100 and P. -150, Swazol (registered trademark) 310, 1000 from Maruzen Petrochemical Co., Ltd., Solvesso (registered trademark) 100, 150, 200 from Ando Parachemy Co., Ltd., Shellzol A100, Shellzol A150 from Shell Chemicals Japan Co., Ltd. Examples include Scherzol S and the like.

In this specification, carbitol acetates refer to esters of acetic acid and diethylene glycol alkyl ether. Examples of carbitol acetates include diethylene glycol monomethyl ether acetate (methyl carbitol acetate), which is an ester of acetic acid and diethylene glycol monomethyl ether, and diethylene glycol monoethyl ether acetate (ethyl carbitol), which is an ester of acetic acid and diethylene glycol monoethyl ether. acetate), diethylene glycol monobutyl ether acetate (butyl carbitol acetate), which is an ester of acetic acid and diethylene glycol monobutyl ether, and the like. One type of carbitol acetate may be used alone, or two or more types may be used in combination. As carbitol acetates, diethylene glycol monoethyl ether acetate (ethyl carbitol acetate) is preferably used, and diethylene glycol monoethyl ether acetate (ethyl carbitol acetate) is particularly preferably used alone.

In the photosensitive resin composition of the present invention, the mass ratio of the petroleum solvent and carbitol acetate in the organic solvent (mass of petroleum solvent: mass of carbitol acetate) is preferably 1:0.5 to 1. :1.2, more preferably 1:0.5 to 1:1.

Further, in the photosensitive resin composition of the present invention, the mass ratio of the petroleum solvent and dipropylene glycol monomethyl ether in the organic solvent (mass of petroleum solvent: mass of dipropylene glycol monomethyl ether) is preferably 1:0. .7 to 1:1.2.

The above-mentioned three types of organic solvents may be blended at the time of preparing the photosensitive resin composition of the present invention, and each component such as the carboxyl group-containing resin constituting the photosensitive resin composition of the present invention. It may be blended at the time of preparation, or it may be included as a solvent for each component. Preferably, all three kinds of organic solvents mentioned above are mixed at the time of preparing the photosensitive resin composition of the present invention.

The organic solvent may contain additional solvent components in addition to the above-mentioned petroleum solvents, carbitol acetates, and dipropylene glycol monomethyl ether. Additional solvent components include ketones such as methyl ethyl ketone and cyclohexanone; glycol ethers such as cellosolve, methyl cellosolve, butyl cellosolve, propylene glycol monomethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol diethyl ether, and tripropylene glycol monomethyl ether; acetic acid. Esters such as ethyl, butyl acetate, butyl lactate, cellosolve acetate, butyl cellosolve acetate, propylene glycol monomethyl ether acetate, dipropylene glycol monomethyl ether acetate, propylene carbonate; known and commonly used solvents such as aliphatic hydrocarbons such as octane and decane. components can be used. These additional components may be used alone or in combination of two or more.

The content of the organic solvent in the photosensitive resin composition is not particularly limited as long as the effects of the present invention are achieved, but petroleum solvents, carbitol acetates, etc. The total content of dipropylene glycol monomethyl ether is preferably adjusted to 50 to 90 parts by mass. In addition, when the organic solvent contains the above-mentioned additional solvent component, the content of the organic solvent in the photosensitive resin composition is such that the total content of the petroleum solvent, carbitol acetates, and dipropylene glycol monomethyl ether is within the above-mentioned range. The total content of all organic solvent components is preferably adjusted to 100 to 150 parts by mass based on 100 parts by mass of the carboxyl group-containing resin.

In the present invention, the organic solvent is evaporated and dried using a hot air circulation drying oven, an IR oven, a hot plate, a convection oven, etc. (equipped with an air heating type heat source using steam, and a method in which the hot air in the dryer is brought into countercurrent contact. and a method of spraying onto the support from a nozzle).

(filler)
The photosensitive resin composition of the present invention may contain a filler, if necessary, in order to increase the physical strength of the coating film. As such a filler, any known inorganic or organic filler can be used, and barium sulfate, spherical silica, hydrotalcite, and talc are particularly preferably used. Furthermore, in order to obtain flame retardancy, metal oxides and metal hydroxides such as aluminum hydroxide can also be used as extender pigment fillers.

The content of the filler is preferably 40% by mass or less based on the total mass of the photosensitive resin composition in terms of solid content. When the filler content exceeds 40% by mass, the viscosity of the photosensitive resin composition increases, coating and moldability deteriorate, and the cured product becomes brittle. More preferably, it is 5 to 40% by mass.

(Other additive ingredients)
The photosensitive resin composition of the present invention optionally contains a colorant, a photoinitiation aid, a cyanate compound, an elastomer, a mercapto compound, a urethanization catalyst, a thixation agent, an adhesion promoter, a block copolymer, and a chain transfer agent. At least one of the following: a polymerization inhibitor, a copper inhibitor, an antioxidant, a rust preventive, a thickener such as organic bentonite or montmorillonite, an antifoaming agent such as a silicone type, a fluorine type, or a polymer type, and a leveling agent. Components such as a silane coupling agent such as an imidazole type, a thiazole type, or a triazole type, a flame retardant such as a phosphorus compound such as a phosphinate, a phosphoric acid ester derivative, or a phosphazene compound can be further blended. For these, materials known in the field of electronic materials can be used.

The photosensitive resin composition of the present invention may be used in liquid form, or may be used in the form of a dry film as described below. Furthermore, when used as a liquid, it may be one-liquid or two-liquid or more.

[Dry film]
The photosensitive resin composition of the present invention can also be in the form of a dry film including a first film and a resin layer made of a photosensitive resin composition formed on the first film. The first film in the present invention is formed by laminating by heating etc. so that a base material such as a substrate and a layer (resin layer) made of a photosensitive resin composition formed on a dry film are in contact with each other and integrally formed. In this case, it refers to one that is at least adhered to the resin layer. The first film may be peeled off from the resin layer in a step after lamination. Particularly in the present invention, it is preferable to peel off the resin layer in the step after exposure. When forming a dry film, the photosensitive resin composition of the present invention is diluted with the above-mentioned organic solvent to adjust the viscosity to an appropriate level, and then coated with a comma coater, blade coater, lip coater, rod coater, squeeze coater, reverse coater, or transfer roll coater. A film can be obtained by coating the first film to a uniform thickness using a , gravure coater, spray coater, etc., and drying for 1 to 30 minutes, usually at a temperature of 50 to 130°C. There are no particular restrictions on the coating film thickness, but it is generally appropriately selected within the range of 1 to 150 μm, preferably 10 to 60 μm after drying.

As the first film, any known film can be used without particular limitation, such as polyester films such as polyethylene terephthalate and polyethylene naphthalate, thermoplastic films such as polyimide films, polyamide-imide films, polypropylene films, and polystyrene films. A film made of resin can be suitably used. Among these, polyester films are preferred from the viewpoints of heat resistance, mechanical strength, handleability, and the like. Moreover, a laminate of these films can also be used as the first film.

Furthermore, from the viewpoint of improving mechanical strength, the thermoplastic resin film as described above is preferably a film stretched in a uniaxial direction or a biaxial direction.

The thickness of the first film is not particularly limited, but can be, for example, 10 μm to 150 μm.

After forming the resin layer of the photosensitive resin composition of the present invention on the first film, a removable layer is added to the surface of the resin layer for the purpose of preventing dust from adhering to the surface of the resin layer. It is preferable to laminate two films. The second film is a film that is formed by laminating and integrally molding by heating etc. so that the base material such as a substrate and the layer (resin layer) made of a photosensitive resin composition formed on the dry film are in contact with each other. , which is peeled off from the resin layer before lamination. As the second peelable film, for example, polyethylene film, polytetrafluoroethylene film, polypropylene film, surface-treated paper, etc. can be used. The second film may be one in which the adhesive force between the resin layer and the second film is smaller than the adhesive force between the resin layer and the first film when the second film is peeled off.

The thickness of the second film is not particularly limited, but can be, for example, 10 μm to 150 μm.

Note that the dry film may be one in which a resin layer is formed by coating and drying the photosensitive resin composition of the present invention on the second film, and the first film is laminated on the surface of the resin layer. good. That is, when manufacturing a dry film in the present invention, either the first film or the second film may be used as the film to which the photosensitive resin composition of the present invention is applied.

(cured product)
The cured product of the present invention is obtained by curing the photosensitive resin composition of the present invention or the resin layer of the dry film described above, and has good resolution required for a solder resist layer. In addition, the above-described photosensitive resin composition of the present invention suppresses crystallization of the components even under cooling and heating cycles, and maintains its composition and properties, so it cannot be used after being exposed to such heating and cooling cycles. Even when the cured product is cured, good resolution is maintained.

(Printed wiring board)
The printed wiring board of the present invention has a cured product obtained from the photosensitive resin composition of the present invention or a resin layer of a dry film. As a method for manufacturing the printed wiring board of the present invention, for example, the photosensitive resin composition of the present invention is adjusted to a viscosity suitable for the coating method using the above-mentioned organic solvent, and then coated on the base material using a dip coating method. After coating by a method such as a flow coating method, a roll coating method, a bar coating method, a screen printing method, or a curtain coating method, the organic solvent contained in the composition is volatilized and dried at a temperature of 60 to 100°C (temporary drying). By doing so, a tack-free resin layer is formed. In the case of a dry film, the resin layer is bonded onto the base material using a laminator or the like so that the resin layer is in contact with the base material, and then the first film is peeled off to form the resin layer on the base material.

The base materials for printed wiring boards include printed wiring boards with circuits formed in advance using copper, etc., flexible printed wiring boards, as well as paper phenol, paper epoxy, glass cloth epoxy, glass polyimide, glass cloth/nonwoven epoxy, and glass cloth. / Paper epoxy, synthetic fiber epoxy, fluororesin/polyethylene/polyphenylene ether, polyphenylene oxide/cyanate, etc. are used in materials such as copper-clad laminates for high frequency circuits, and all grades (FR-4 etc.) are used. Examples include copper-clad laminates, metal substrates, polyimide films, polyethylene terephthalate films, polyethylene naphthalate (PEN) films, glass substrates, ceramic substrates, wafer plates, and the like.

The dry film is preferably laminated onto the base material under pressure and heat using a vacuum laminator or the like. By using such a vacuum laminator, when using a circuit board with a circuit formed thereon, even if the circuit board surface is uneven, the dry film will adhere to the circuit board, so there will be no air bubbles mixed in, and the board The ability to fill in the recesses on the surface is also improved. The pressurizing condition is preferably about 0.1 to 2.0 MPa, and the heating condition is preferably 40 to 120°C.

Volatilization drying performed after applying the photosensitive resin composition of the present invention is carried out using a hot air circulation drying oven, IR oven, hot plate, convection oven, etc. (equipped with an air heating type heat source using steam). This can be carried out using a method in which hot air is brought into countercurrent contact and a method in which hot air is blown onto the support from a nozzle.

After forming a resin layer on the base material, it is selectively exposed to active energy rays through a photomask with a predetermined pattern formed thereon, and the unexposed areas are treated with a dilute alkaline aqueous solution (for example, 0.3 to 3 mass% sodium carbonate aqueous solution). The cured product is developed to form a pattern. In the case of a dry film, after exposure, the first film is peeled off from the dry film and developed to form a patterned cured product on the base material. Note that, as long as the properties are not impaired, the first film may be peeled off from the dry film before exposure, and the exposed resin layer may be exposed and developed. Furthermore, by irradiating the cured product with active energy rays and then heat curing (e.g. 100 to 220°C), or by irradiating active energy rays after heat curing, or final finish curing (main curing) with only heat curing, adhesion can be achieved. Forms a cured product with excellent properties such as hardness and hardness.

The exposure machine used for active energy ray irradiation may be a device equipped with a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, a metal halide lamp, a mercury short arc lamp, etc., and irradiates ultraviolet rays in the range of 350 to 450 nm. , a direct drawing device (for example, a laser direct imaging device that draws an image directly with a laser using CAD data from a computer) can also be used. The lamp light source or laser light source of the direct drawing machine may have a maximum wavelength in the range of 350 to 450 nm. The exposure amount for image formation varies depending on the film thickness, etc., but can generally be in the range of 10 to 1000 mJ/cm ² , preferably 20 to 800 mJ/cm ² .

Development methods include dipping, showering, spraying, brushing, etc. Developers include potassium hydroxide, sodium hydroxide, sodium carbonate, potassium carbonate, sodium phosphate, sodium silicate, and ammonia. An alkaline aqueous solution of amines or the like can be used.

When curing the photosensitive resin composition of the present invention, further curing may be promoted by irradiating ultraviolet rays after the above-mentioned exposure and development with active energy ray irradiation (post-UV), or heating. It is also possible to accelerate heat curing (post-cure). By performing post-UV and post-cure treatments, various properties such as heat resistance, chemical resistance, moisture absorption resistance, adhesion, and electrical properties of the cured product of the photosensitive resin composition can be further improved.

Hereinafter, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to these Examples. In the examples, "parts" and "%" are based on mass unless otherwise specified.

[Preparation of photosensitive resin composition]
(Example of synthesis of carboxyl group-containing resin)
Before preparing the photosensitive resin composition, the carboxyl group-containing resin used in this example was prepared according to the procedure shown below.
First, 220 parts of a cresol novolac type epoxy resin (EPICLON (registered trademark) N-695, manufactured by Dainippon Ink & Chemicals Co., Ltd., epoxy equivalent: 220) was placed in a four-necked flask equipped with a stirrer and a reflux condenser. 206 parts of methoxy-3-methyl-1-butyl acetate (Solfit AC) was added and heated to dissolve. Next, 0.1 part of a polymerization inhibitor (hydroquinone) and 2.0 parts of a reaction catalyst (triphenylphosphine) were added. The resulting mixture was heated to 95-105°C, 72 parts of acrylic acid was gradually added dropwise, and the mixture was allowed to react for 16 hours. The obtained reaction product was cooled to 80 to 90°C, 91.2 parts of tetrahydrophthalic anhydride was added, and the reaction product was reacted for 8 hours. A polymer was obtained. The resulting photosensitive prepolymer had a nonvolatile content of 65% and a solid acid value of 87.8 mgKOH/g.

Next, each component shown in Table 1 below was mixed in the amount shown in the same table (solid content, the amount of organic solvent listed in the table was blended at the time of preparing the photosensitive resin composition), and the mixture was mixed with a stirrer. After preliminary mixing using a three-roll mill, the photosensitive resin compositions of Examples 1 to 4 and Comparative Examples 1 to 2 were prepared. The details of each component in Table 1 are as follows.
Carboxyl group-containing resin (carboxyl group-containing resin obtained by the above-mentioned synthesis example)
Thermosetting component 1: Phenol novolac type epoxy resin (RE-306-SA9, manufactured by Nippon Kayaku Co., Ltd.)
Thermosetting component 2: Alicyclic epoxy resin (Epolead (registered trademark) PB3600, manufactured by Daicel Corporation)
Thermosetting component 3: Biphenol type epoxy resin (YX-4000, manufactured by Mitsubishi Chemical Corporation)
Photopolymerizable monomer: Dipentaerythritol hexaacrylate Other additive components 1: Antifoaming agent (KS-66, manufactured by Shin-Etsu Chemical Co., Ltd.)
Other additive components 2: Thickener (ORBEN-MF, manufactured by Shiraishi Kogyo Co., Ltd.)
Other additive components 3: Blue pigment Other additive components 4: Yellow pigment Thermosetting catalyst: Melamine Filler: Surface treatment barium sulfate (B-30, manufactured by Sakai Chemical Industry Co., Ltd.)
Photoinitiator 1: α-aminoacetophenone photoinitiator (Omnirad (registered trademark) 379, manufactured by IGM Resins)
Photoinitiator 2: α-aminoacetophenone photoinitiator (Omnirad (registered trademark) 369E, manufactured by IGM Resins)
Photoinitiator 3: α-hydroxyacetophenone photoinitiator (liquid photoinitiator, Omnirad (registered trademark) 1173, manufactured by IGM Resins)
Organic solvent 1: Alcohol solvent (Solfit AC, manufactured by Kuraray Co., Ltd.)
Organic solvent 2: Carbitol acetates (ethyl carbitol acetate (diethylene glycol monoethyl ether acetate))
Organic solvent 3: Petroleum solvent (Ipsol #150, manufactured by Idemitsu Kosan Co., Ltd.)
Organic solvent 4: Dipropylene glycol monomethyl ether Organic solvent 5: Methyl ethyl ketone

[Evaluation of crystal generation due to cooling and heating cycles]
Crystal generation of each of the photosensitive resin compositions of Examples and Comparative Examples due to cooling and heating cycles was evaluated according to the following procedure. Weighed out 50 g of each photosensitive resin composition of Examples and Comparative Examples, left it for one day at room temperature, and then left it for another day at 4°C or less, one cycle, and after each cycle 1 to 3 times. A photosensitive resin composition was produced.

Using a coating glass rod with tape wrapped around both ends of the glass rod to form a gap of 200 μm, the resulting photosensitive resin composition after each cycle was applied to a glass substrate and dried at 80° C. for 20 minutes. A substrate for evaluation of crystal generation due to cooling and heating cycles was prepared. Each evaluation substrate was visually observed to confirm the presence or absence of crystals on each evaluation substrate, and the generation of crystals due to cooling/heating cycles in each photosensitive resin composition was evaluated according to the following evaluation criteria. The results are shown in Table 1.
◎: Crystals with a maximum diameter of 200 μm or less are not observed.
Good: One or more and two or less crystals with a maximum diameter of 200 μm or less are observed.
×: Three or more crystals with a maximum diameter of 200 μm or less are observed.

[Evaluation of drying control range]
The photosensitive resin compositions of Examples and Comparative Examples were screened onto the surface of a buff roll-polished FR-4 board on which a circuit pattern of 150 mm in length, 95 mm in width, and 1.6 mm in thickness was formed after three cooling/heating cycles. After printing, the film was coated so that the film thickness after drying was 20 μm, and dried at 80°C for 60 minutes, 65 minutes, and 70 minutes, respectively, to obtain a substrate for drying control width evaluation having a dried coating film. Created.

Each board for evaluating drying control width was developed for 60 seconds in a printed wiring board developer using a 1% by mass aqueous sodium carbonate solution at a liquid temperature of 30°C as a developer. After development, each substrate for evaluation of drying control width was visually observed to confirm the presence or absence of a dried coating film (residue from development), and the drying control width of each photosensitive resin composition was evaluated according to the following evaluation criteria. The results are shown in Table 1.
◯: No development residue was left on any of the drying control width evaluation substrates dried at 80° C. for 60 minutes, 65 minutes, and 70 minutes.
Δ: Remains of development occur on one of the drying control width evaluation substrates dried at 80° C. for 60 minutes, 65 minutes, and 70 minutes.
x: Out of the drying control width evaluation substrates dried at 80° C. for 60 minutes, 65 minutes, and 70 minutes, at least two of the drying control width evaluation substrates have development residues.

[Evaluation of who you are]
Using a syringe, drop 0.15 ml of each photosensitive resin composition after three cooling/heating cycles onto the surface of a copper-clad laminate measuring 150 mm long, 95 mm wide, and 1.6 mm thick, and leave it for 1 minute. The copper-clad laminate was propped up on a rack. The copper-clad laminate was placed on a rack so that the angle between the surface opposite to the surface on which the photosensitive resin composition was dropped and the horizontal plane was 80°. Next, the photosensitive resin composition was dried at 150° C. for 30 minutes while standing on a rack to produce a substrate for evaluation of sagging properties.

For each substrate for sagging property evaluation, measure the length of the sag of the photosensitive resin composition (the length from the end on the side where it was dropped to the end on the side where the photosensitive resin composition sag and stretched), The sagging properties of each photosensitive resin composition were evaluated according to the following evaluation criteria. The results are shown in Table 1.
◎: The length of the droop is within 1 cm.
○: The length of the droop is more than 1 cm and less than 2 cm.
×: The length of the droop is more than 2 cm.

[Printability (plate separation) evaluation]
The photosensitive resin compositions of Examples and Comparative Examples were applied to the surface of a buff roll-polished FR-4 substrate measuring 150 mm long, 95 mm wide, and 1.6 mm thick, and the film thickness after drying was Printing was performed by screen printing so that the thickness was 20 μm. The time from immediately after the photosensitive resin composition was printed until the photosensitive resin composition and the printing plate separated was measured, and the printability (plate separation) of each photosensitive resin composition was evaluated according to the following evaluation criteria. . The results are shown in Table 1.
◎: The time it takes for the photosensitive resin composition and the printing plate to separate after printing is within 1 second.
Good: The time taken for the photosensitive resin composition and the printing plate to separate after printing is more than 1 second and less than 2 seconds.
×: The time taken for the photosensitive resin composition and the printing plate to separate after printing is more than 2 seconds.

[Evaluation of dryness to touch]
After drying, the photosensitive resin compositions of Examples and Comparative Examples were screen printed on the surface of a buff roll-polished copper-clad laminate measuring 150 mm long, 95 mm wide, and 1.6 mm thick. The entire surface was printed to a film thickness of 20 μm and dried at 80° C. for 30 minutes to produce a substrate for evaluating dryness to the touch having a dry coating film of the photosensitive resin composition.

After pressing your finger (index finger) against each dryness to touch evaluation substrate for 3 seconds with enough force to touch the entire fingertip, visually observe the contact area to confirm the presence or absence of fingerprints. The dryness to the touch of the composition was evaluated according to the following evaluation criteria. The results are shown in Table 1.
○: No fingerprints remain after touching with fingers for 3 seconds.
△: A part of the fingerprint remains after touching the finger for 3 seconds.

From the evaluation results shown in Table 1, the photosensitive resin compositions of each example sufficiently suppressed the generation of crystals due to cooling and heating cycles, and even when used after cooling and heating cycles, the photosensitive resin compositions exhibited good performance required for printed wiring board manufacturing. It can be seen that various characteristics (drying control width, sagging properties, and printability) are exhibited. That is, in a photosensitive resin composition containing a carboxyl group-containing resin, a photopolymerization initiator, and an organic solvent, an α-aminoacetophenone photopolymerization initiator is blended as the photopolymerization initiator, and a petroleum-based solvent is used as the organic solvent. It can be seen that by blending carbitol acetates and dipropylene glycol monomethyl ether, it is possible to sufficiently suppress the generation of crystals due to cooling and heating cycles, and to achieve various good properties required during the manufacture of printed wiring boards. On the other hand, it can be seen that none of the photosensitive resin compositions of the comparative examples achieves both sufficient suppression of crystal generation due to cooling and heating cycles and good properties required during the production of printed wiring boards.

Claims

A photosensitive resin composition containing a carboxyl group-containing resin, a photopolymerization initiator, and an organic solvent,
The photopolymerization initiator includes an α-aminoacetophenone photopolymerization initiator,
A photosensitive resin composition, wherein the organic solvent contains a petroleum solvent, carbitol acetates, and dipropylene glycol monomethyl ether.
The photosensitive resin composition according to claim 1, wherein the mass ratio of the petroleum solvent and carbitol acetate in the organic solvent is 1:0.5 to 1:1.2.
The photosensitive resin composition according to claim 1, wherein the mass ratio of the petroleum solvent and dipropylene glycol monomethyl ether in the organic solvent is 1:0.7 to 1:1.2.
The photosensitive resin composition according to claim 1, wherein the total content of the petroleum solvent, carbitol acetates, and dipropylene glycol monomethyl ether is 50 to 90 parts by mass based on 100 parts by mass of the carboxyl group-containing resin. thing.
2. The α-aminoacetophenone photopolymerization initiator comprises 2-dimethylamino-2-(4-methylbenzyl)-1-(4-morpholin-4-yl-phenyl)-butan-1-one. 1. The photosensitive resin composition according to 1.
The photosensitive resin composition according to claim 1, which is used for forming a solder resist layer.
A method for manufacturing a printed wiring board comprising a solder resist layer, the method comprising the step of forming the solder resist layer by curing the photosensitive resin composition according to claim 1.