JP2533557B2 - Photosensitive resin composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention is an alkali-developable photosensitive material that can be effectively applied to a solder resist ink having excellent heat resistance, electric insulation properties and chemical resistance used for printed wiring boards. It relates to a resin composition.

[Conventional technology]

Solder resist ink is usually applied to the printed wiring board by screen printing to protect the exposed conductor circuits of the printed wiring board and to prevent solder from adhering to unnecessary parts of the circuit. Various properties such as heat resistance, electrical insulation and chemical resistance are required.

Conventionally, there are two types of solder resist ink, a thermosetting type and an ultraviolet curing type. The former is mainly an epoxy resin and the latter is mainly a resin composition in which a polyvalent vinyl monomer is added to epoxy acrylate. Since the former is superior to the latter in various performances such as heat resistance, it has become the mainstream in the printed wiring boards for industrial equipment that are highly demanded for reliability such as computers, while the workability and productivity are high. The latter is predominant in printed wiring boards for consumer equipment, where

In recent years, as the needs for higher performance, higher reliability, and diversification of electronic devices and parts, such as miniaturization and weight reduction, have increased, the demand for higher density and higher precision of printed wiring boards has increased. It is getting tougher. Among them, with the progress of surface mounting technology, discrete parts such as capacitors and resistance elements have been made into chip parts, and the mounting pads of the chip parts to the printed wiring board become smaller, so the clearance is designed as little as possible. The number of cases is increasing. However, since the conventional solder resist ink forms an image by screen printing, it becomes difficult to deal with higher density and higher accuracy due to the problems of seeping into the land and insufficient embedding of ink between the lines. ing.

Under these circumstances, a liquid solder resist ink for forming an image by a photographic developing method (photo system) has recently attracted attention as a solder resist suitable for a high density and high precision printed wiring board.

The photo-developing method is a method in which a photosensitive resin composition is applied to a printed wiring board having an exposed conductor, dried and brought into close contact with a negative film, exposed, and then an unexposed portion is developed with a solvent or an alkaline solution to form an image. Is.

By this method, problems such as bleeding of the resist ink to the land portion and insufficient embedding between the lines are almost solved.

[Problems to be solved by the invention]

However, since the developing method of the solder resist ink used in the photographic developing method is often required to have extremely high physical properties of the protective film, particularly heat resistance, electrical insulation characteristics and chemical resistance. The solvent developing type, which is relatively easy to balance these characteristics, is ahead.

However, many solvents currently used in solvent-developable solder resist inks are chlorine-based compounds such as trichloroethane, and development with an alkaline aqueous solution is desired from the viewpoints of environmental problems, pollution problems, solvent costs, and the like.

However, no solder resist ink capable of being developed with an aqueous alkaline solution has been sufficiently detected in terms of physical properties as a protective film in terms of heat resistance, electrical insulation properties and chemical resistance.

In view of such circumstances, as a result of various investigations by the present inventors, as compared with a conventional solvent-developable solder resist ink-like photosensitive resin composition or a screen-printing solder resist ink, heat resistance and electrical insulation are improved. Without deteriorating the physical properties such as resistance and chemical resistance,
We have found a photosensitive resin composition useful as a solder resist ink for a high-density, high-precision printed wiring board with exposed conductors, which can be developed by an alkaline aqueous solution.

The present invention has been made based on such knowledge.

[Means for solving problems]

That is, the present invention provides (A) an epoxy resin represented by the general formula (1), A half-esterified epoxidized vinyl compound obtained by reacting a reaction product obtained by ring-opening / addition of an unsaturated monobasic acid with an acid anhydride, (B) mono- or polyvalent epoxy compound, (C) light A photosensitive resin composition comprising a heavy unsaturated compound and (D) a photoinitiator.

The thiobisphenol type epoxy resin (1) which is the precursor of the component (A) used in the present invention is synthesized by the reaction of polythiopolyphenol obtained by the reaction of phenol with metal sulfur and epichlorohydrin. 5
When it is above, the viscosity in the reaction system becomes too high and it becomes difficult to control the reaction. Therefore, n is preferably 4 or less.

The reaction of phenol with metal sulfur is usually carried out at a temperature of 150 to 200 ° C. in the presence of alkali. For example, the charging ratio of both is 1 gram atom to 2 gram atom of sulfur per mole of phenol. preferable. For example, T.
J. Rawlings et.al, Tetrahedron 25 4
It can be synthesized according to the reaction conditions described in 593 (1969). The reaction between the polythiopolyphenol obtained by the reaction and epichlorohydrin can be carried out in the same manner as the usual epoxy resin production conditions. For example, RKBans
al and R. Agarwal, Die Angewandte Makromolekulare Che
mie) 127 43 (1984). Needless to say, a part or all of epichlorohydrin can be replaced with a 2-alkyl-substituted epichlorohydrin such as 2-methylepichlorohydrin.

The unsaturated-basic acid used in the present invention is typically acrylic acid, methacrylic acid, crotonic acid, sorbic acid, monomethylmalate, monopropylmalate, monobutylmalate, mono (2-ethylhexyl) malate, or the like. These unsaturated-basic acids can be used alone or as a mixture of two or more kinds.

The reaction between the thiobisphenol type epoxy resin (1) of the present invention and the unsaturated-basic acid can be carried out by a usual ring-opening addition reaction of an epoxy group.

The preferred amount of unsaturated monobasic acid to be used for the thiobisphenol type epoxy resin (1) is in the range of 1: 0.80 to 1.10 in terms of the number of epoxy groups: the number of carboxyl groups in gram equivalents.

When the gram equivalent number of the carboxyl group exceeds 1.10, the amount of free acid increases, and the reaction product thereof adversely affects the heat resistance of the coating film after curing.
When it is less than 80, the residual epoxy groups increase, and gelation easily occurs in the reaction with the acid anhydride, which is not preferable.

The above ring-opening addition reaction is usually performed at 80 ° C to 150 ° C. 150
If the temperature exceeds 80 ° C, gelation tends to occur, and if the temperature is lower than 80 ° C, the reaction takes too long, which is not preferable.

To start the above reaction, usually, the epoxy resin (1) is dissolved in a hydrophilic solution such as cellosolve acetate-based, ketone-based, alcohol-based, etc., and the unsaturated monobasic acid is usually used for 10 hours at the above reaction temperature. Incubate for 40 hours.

The reaction rate of the reaction was calculated from the rate of change of acid value, and the reaction rate was 9
The reaction is terminated when it reaches about 8.0% or more. In addition,
It is preferable to use a tertiary amine such as triethylamine, triethanolamine, morpholine, 2,4,6- (trisdimethylamino) -phenol as a reaction accelerator.

On the other hand, in order to prevent the formation of a polymer during the reaction, usually, hydroquinone, hydroquinone monomethyl ether, t-butylhydroquinone, t-butylcatechol,
It is preferable to use a known polymerization inhibitor such as benzoquinone or phenothiazine.

The thus obtained reaction product, an epoxy vinyl ester compound, is further esterified by reaction with an acid anhydride to obtain a half-esterified compound.

Examples of the acid anhydride used in the present invention include maleic anhydride, phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, clodendic acid anhydride (HET acid), pyromellitic anhydride, 3,3 ′, 4,4. Typical examples thereof include'-benzophenone tetracarboxylic acid anhydride, methyl nadic acid anhydride, dodecyl succinic anhydride, dichloromaleic anhydride and tetrachlorophthalic anhydride.

In the half-esterification reaction, the reaction product, an epoxy vinyl ester compound, is reacted in the range of 0.1 gram equivalent to 10 gram equivalent per hydroxy group per 1 gram molecule of acid anhydride, but preferably 0.2 gram equivalent. It is in the range of 5 gram equivalents, and most preferably 1 gram equivalent of epoxy vinyl ester compound is used per 1 gram molecule of the acid anhydride to complete the ring-opening addition of the acid anhydride.

The above ring-opening addition reaction is usually carried out at 50 ° C to 200 ° C, but 80 ° C to 150 ° C in order to prevent the formation of diester and gelation
C. is preferable.

The reaction is usually carried out by adding a predetermined amount of an acid anhydride and a solvent to the epoxy vinyl ester compound solution,
Allow to react for 40 hours.

The solvent used for the reaction is preferably the same hydrophilic solvent as the solvent used for the epoxy vinyl esterification reaction of the thiobisphenol type epoxy resin (1).

The end point of the reaction may be the time point at which the absorption reduction of the acid anhydride is tracked by infrared absorption spectrum and the absorption completely disappears.

As the reaction accelerator, it is preferable to use tertiary amines such as triethylamine, triethanolamine, morpholine, pentamethyldiethylenetriamine or quaternary ammonium salts. In order to prevent the formation of a polymer during the reaction, hydroquinone, hydroquinone monomethyl ether, t-butylhydroquinone,
It is also preferable to use a known polymerization inhibitor such as t-butylcatechol, benzoquinone and phenothiazine.

The amount of the half-esterified epoxy vinyl compound (A) of the present invention is usually 5 with respect to the photosensitive resin composition of the present invention.
It is preferably in the range of not less than 95% by weight and usually not less than 10% by weight
80% by weight or less is more preferable.

As the mono- or polyvalent epoxy compound which is the component (B) in the present invention, any so-called epoxy resin prepolymer can be used, but bisphenol A type, bisphenol F type, phenol / volac type, cresol novolac. Each type of epoxy resin is preferable, for example, Epicoat 154 and Epicoat 8 manufactured by Shell Co.
12, Epikote 828, Epikote 1001, Epikote 100
4, Epicoat 1007, Epicoat 1009; Ciba Geigy Araldite 6071, Araldite 6084, Araldite
6097; Dow DER331, 332, 333, 661, 664, 667, 66
9; EOCN-102, 103, 104, 1020, 1025 and the like manufactured by Nippon Kayaku Co., Ltd. Denacol manufactured by Nagase Kasei Co., Ltd.
EX-411, EX-421, EX-301, EX-313, EX-211, EX-6
11, EX-811, EX-911; preferred are epoxy compounds of triglycidyl isocyanurate (Nissan Tevic, etc.) manufactured by Nissan Chemical Co., Ltd. In addition, a vinyl copolymer of glycidyl acrylate or glycidyl methacrylate can be used.

These mono- or polyhydric epoxy compounds are used alone or in a mixture, and the amount thereof is 5 in the photosensitive resin composition.
% By weight to 80% by weight, more preferably 5% by weight or more
It is 50% by weight or less.

As the photopolymerizable unsaturated compound which is the component (C) of the present invention, acrylic acid esters of polyhydric alcohols and methacrylic acid esters of polyhydric alcohols are suitable, and triethylene glycol, tetraethylene glycol, ethylene glycol, propylene. Typical examples thereof include acrylic acid esters or methacrylic acid esters such as glycol, trimethylolpropane, pentaerythritol, dipentaerythritol, and neopentyl glycol.

In addition, methylene-bis-acrylamide, methylene-
Amides such as bis-methacrylamide, acrylamide, methacrylamide; and reaction products of diol acrylate or diol methacrylate with diisocyanate; also triacrylformal, triallyl cyanurate, tris (2-acryloyloxyethylene) isocyanate, such as Hitachi FA-731A, FA-73 manufactured by Kasei
1M, Toagosei Kagaku Co. Aronix M-215, M-315,
M-325 and the like can also be used.

These photopolymerizable unsaturated compounds may be used alone or in combination of two or more, and the amount thereof used is 5% by weight or more and 60% by weight or less, more preferably 10% by weight or less in the photosensitive resin composition.
It is from 50% by weight to 50% by weight.

As the photoinitiator which is the component (D) of the present invention, any photoinitiator can be used as long as it is an initiator that initiates the polymerization of the unsaturated compound upon irradiation with actinic rays such as ultraviolet rays,
For example, benzophenones such as benzophenone and Michler's ketone; benzoin alkyl ethers such as benzoin, benzoin butyl ether, benzoin isobutyl ether, and benzoin isopropyl ether; 2,2-dimethoxy-2-phenylacetophenone, 2,2-diexacetophenone, 2,2 -Acetophenones such as dichloro-4-phenoxyacetophenone; 2-hydroquin-2-methylpropiophenone, 4-isopropyl-2-hydroxy-2-methylpropiophenone, 2-ethylanthraquinone, 2-t-butylanthraquinone , Anthraquinones such as 2-chloroanthraquinone; thioxanthones such as diethylthioxanthone, diisopropylthioxanthone and chlorothioxanthone; other benzyl, 1
-Hydroxycyclohexyl phenyl ketone, 2-methyl- [4- (methylthio) phenyl] -2-morpholino-1-propanone, P-dimethylaminobenzoic acid ethyl ester, P-dimethylaminobenzoic acid isoamyl and the like can be mentioned.

These photoinitiators may be used alone or as a mixture, and the amount thereof used is 0.1% by weight or more and 20% by weight or less, more preferably 1% by weight or more and 15% by weight or less in the photosensitive resin composition.

In the present invention, the above (A), (B),
It is possible to include various modifiers and additives other than the components (C) and (D).

Hydroquinone, t-
Thermal polymerization inhibitors such as butyl catechol for improving storage stability; various amine-based epoxy resin curing agents such as diethylenetriamine and dicyandiamide; linear polymer binders such as cellulose; benzotriazole and unsaturated phosphates Compound (for example, Kayama manufactured by Nippon Kayaku Co., Ltd.
PM-1, PM-2, etc.) and the like, such as an adhesion improver with a metal such as a copper circuit.

Further, additives made of various fillers are also possible, and examples thereof include fine powder silica, talc, quartz powder, and inorganic fillers such as barium sulfate.

Furthermore, if necessary, a silane coupling agent, a leveling agent, an antifoaming agent, a coloring pigment, a dye or the like can be added.

As described above, the photosensitive resin composition of the present invention is usually 5% by weight.
Toluene, methyl ethyl ketone, isophorone, cyclohexanone, cellosolve, cellosolve acetate, butyl cellosolve
Butyl cellosolve acetate, butyl carbitol, butyl carbitol acetate, mineral split, trichloroethane, trichloroethylene, etc. are dissolved in an organic solvent to adjust the photosensitive liquid, and a normal coating method or printing such as a roll coater method or a screen printing method. A method is used to form a photosensitive layer on the printed wiring board to be protected.

It is also possible to apply a photosensitive solution on a film such as polyethylene terephthalate in advance, and then dry the photosensitive film on a printed wiring board to be protected by using a roll and a vacuum press.

After forming a photosensitive layer on a printed wiring board, an actinic ray is irradiated through a negative mask to cure the exposed portion. The exposure source may be any as long as it effectively radiates ultraviolet rays, for example, carbon arc, mercury vapor arc, ultraviolet radiation fluorescent lamp, argon glow lamp,
Preferred examples include electron sensitizers and solar lamps, and particularly effective exposure sources include high-pressure or ultra-high-pressure mercury lamps and metal halide lamps with an appropriate light amount of 100 to 8
It is about 00 mJ / cm ² .

As described above, after exposing the photosensitive resin composition of the present invention, the unexposed portion is eluted using an alkaline aqueous solution as a developer,
develop.

Examples of such a developing base include alkali metal hydroxides such as lithium hydroxide, sodium hydroxide and potassium hydroxide, weak acid alkali metal salts, ie, lithium, sodium and potassium carbonates or bicarbonates and water-soluble bases. A salt or the like is typical, and the salt concentration is generally 0.01 to 10% by weight, and in the phenomenon of the photosensitive resin composition of the present invention, an aqueous solution of 0.1 to 5.0% by weight of sodium carbonate is most preferable.

After development, it is usually heated at 100 ° C. to 200 ° C. for 10 minutes to 5 hours to be cured.

[Action effect]

Thus, the protective coating obtained from the photosensitive resin composition of the present invention is not attacked by organic solvents such as toluene and trichlene,
On the other hand, although it can be developed with an alkali, it has excellent chemical resistance such as being sufficiently resistant to a strongly acidic or alkaline aqueous solution.

Furthermore, since the protective film obtained from the photosensitive resin composition of the present invention is excellent in heat resistance and electric insulation, it is particularly useful as a solder resist for printed wiring boards.

The photosensitive resin composition of the present invention can also be used as a touch-resistant film for ordinary etching, plating, etc. by only exposure and development without performing heat treatment as described above.

〔Example〕

Hereinafter, the present invention will be described in detail with reference to examples. In the examples, "parts" means "parts by weight".

 The performance of the resist film was evaluated by the following method.

B. Pencil hardness A scratch test was performed according to JIS D-0202 to determine the hardness of the pencil when scratched.

(B) Adhesiveness According to JIS D-0202, an eye-eye test was conducted to check the number of eye-eyes remaining after peeling off the tape.

C, Solvent resistance Acetone, methyl ethyl ketone, trichlene, trichloroethane at room temperature (20 ~ 25 ℃) for 12 hours after swelling, peeling, the presence or absence of cracks and gloss,
The change in color tone and the softening of the film were examined.

D. Chemical resistance 10% hydrochloric acid, 10% sulfuric acid, 10% sodium hydroxide aqueous solution at room temperature (20-25 ° C) for 12 hours at room temperature (20-25 ° C), swelling, peeling, cracks, and gloss , The change in color tone and the softening of the film were examined.

E, Soldering heat resistance After dipping in a solder bath at 270 ° C for 30 seconds, the presence or absence of blistering, peeling, cracks, and changes in gloss and color tone were examined.

F. Electrical insulation The insulation resistance was measured after exposure for 1000 hours in an environment of 60 ° C and 95% RH.

And withstand voltage of 600 V, 10 mA, and the presence or absence of dielectric breakdown under a load of 1 minute were examined.

[Reference Example 1] [Synthesis of half-esterified compound (A-1)] Thiobisphenol type epoxy resin represented by the formula (2) (n≈2, epoxy equivalent 200, manufactured by Mitsui Toatsu Fine Co., Ltd.), 300 parts 100 parts (0.5 gram equivalent), acrylic acid 36 parts (0.5 gram equivalent) and 90 parts cellosolve acetate
ml thermometer, stirrer and condenser tube equipped with a three-necked flask, hydroquinone, 0.135 parts and 2,
Add 0.13 parts of 4,6 tris (dimethylaminomethyl) phenol, and stir at 110 ° C for 30 hours to react while blowing air into the system at a rate of about 1 cc / min to prevent polymerization and obtain a reaction product. It was The acid value of the reaction product was 1 or less.

Next, 170 parts of the reaction product (solid content 60%, 0.375 gram equivalent per 1 OH group), 4-methylhexahydrophthalic anhydride (Ricacid MH-700, manufactured by Shin Nippon Rika Co., Ltd.) 63
Parts (0.375 gram molecule), 80 parts cellosolve acetate,
Put 0.160 parts of hydroquinone into a three-necked flask equipped with a 300 ml thermometer, a stirrer and a cooling tube, and blow air into the system at a speed of about 1 cc / min to prevent polymerization.
The mixture was stirred and reacted at 105 ° C. for 8 hours to obtain a half-esterified epoxy vinyl compound (A-1).

According to the infrared absorption spectrum of the half-esterified epoxy vinyl compound, the absorption of acid anhydride (near 1820 cm ⁻¹ ) is
I confirmed that it almost disappeared.

Example 1 A half-esterified epoxy vinyl compound (A-1) obtained by the above reaction was used to prepare a photosensitive solution having the following formulation, and the photosensitive solution was evaluated.

Part Half-esterified compound (A-1) 65 Cresol novolac type epoxy resin (manufactured by Asahi Chemical Industry Co., Ltd. ECN-299) (B-1) 25 pentaerythritol triacrylate (C-1) 20 benzophenone (D-1) 5 Michler's Ketone (D-1 ') 2 Benzotriazole 3 Phthalocyanine Green 2 Cellosolve Acetate 50 First, apply this solution on a printed wiring board with exposed conductors using a doctor blade and use a hot air electric thermostat.
It was dried at 70 ° C for 20 minutes.

The surface of the obtained coating film was smooth and had no tack, and the film thickness was 21 μm on the circuit.

Then, through a negative mask for pattern formation of three pins and a small through hole of 0.4 mmΦ, irradiation was performed for 2 minutes and 30 seconds from a distance of 60 cm using a 2 KW ultra-high pressure mercury lamp. The integrated light quantity at this time was 600 mJ / cm ² . Then, spray development was carried out at 30 ° C. for 1 minute using a 2 wt% sodium carbonate aqueous solution.

The unexposed part was dissolved, a protective film having a highly accurate image equivalent to a negative mask was obtained, and the embedding property between lines was also good. After that, heat treatment was further performed at 140 ° C. for 50 minutes to cure, and then the coating film was subjected to various performance evaluation tests.

Example 1 The half-esterified epoxy vinyl compound (A-1) of Example 1 was kneaded with a triple roll according to the following formulation to obtain an ink of 150 PS (25 ° C).

Part Half-esterified compound (A-1) (A-2) 65 Cresol novolac type epoxy resin (ECN-299 manufactured by Asahi Chemical Industry Co., Ltd.) (B-2) 25 Trimethylolpropane triacrylate (C-2)
10 Pentaerythritol triacrylate (C-2 ')
10 Benzophenone (D-2) 5 Himilarketone (D-2 ′) 2 Methacryloyloxyethyl Phosphate (Nippon Kayaku Co., Ltd. Kayama-PM-2) 3 Silica 100 Cellosolve Acetate 20 Exposure of conductor using the above ink The resulting printed wiring board was coated on the entire surface with a screen-printing machine with 180 mesh and Tetron cloth, and dried in a hot air electric thermostat at 70 ° C for 20 minutes. The surface of the obtained coating film was smooth and had no tack, and the film thickness was 18 μm on the circuit. Thereafter, exposure, development and post-curing were performed in the same manner as in Example 1 to prepare a test piece.

Reference Example 2 In the half-esterification reaction of Reference Example 1, 57 parts of tetrahydrophthalic anhydride (Ricacid TH, manufactured by Shin Nippon Rika Co., Ltd.) was used in place of 4-methylhexadrophthalic anhydride.
The half-esterified compound (A-3) was prepared according to Reference Example 1 except that 375 g of molecule) was used.

Example 3 The half-esterified epoxy vinyl compound (A-3) of Reference Example 2 was used to prepare a photosensitive solution having the following formulation, and the solution was subjected to an evaluation test.

Part Half-esterified compound (A-3) 70 Bisphenol A type epoxy resin (Epicote 1001 manufactured by Yuka Shell Epoxy Co., Ltd.) (B-3) 10 Same as above (Epicote 1007) (B-3 ′) 10 Dipentaerythritol Hexaacrylate (C-3) 25 1-hydroxycyclohexyl phenyl ketone (D-3) 32,2'-dimethoxy-2-phenylacetophenone (D-3 ') 3 P-dimethylaminobenzoic acid ethyl ester (D-3 ″) 1 Benzotriazole 0.3 Phthalocyanine Green 3 1/1 mixed solution of cellosolve acetate / cyclohexanone 65 First, apply this solution on a printed wiring board with exposed conductors using a roll coater, and then heat it in a hot air electric thermostat 70
C., and dried for 20 minutes. The surface of the obtained coating film is smooth,
There was no tack and the film thickness was 18 μm on the circuit.

Thereafter, exposure, development and post-curing were performed in the same manner as in Example 1 to prepare a test piece.

Example 4 The half-esterified compound (A-3) of Example 3 was kneaded with a triple roll according to the following formulation to obtain a uniform ink.

Part Half-esterified compound (A-3) (A-4) 65 Triglycidyl isocyanurate (Nissan Chemical Industry Co., Ltd.)
TEPIC-G) (B-4) 15 dipentaerythritol hexaacrylate (C-4) 20 2-methyl- [4- (methylthio) phenyl] -2-morpholino-1-propanone (Nippon Ciba-Geigy Co., Ltd.) Irgacure-907) (D-4) 42,4-diethylthioxanthone (D-4 ′) 2 P-dimethylaminoethylbenzoate (D-4 ″) 2 methacryloyloxyethyl phosphate (Nippon Kayaku Co., Ltd.) Kayama-PM-2) 2 Dicyandiamide 1 Phthalocyanine Green 3 Talc 30 Mineral Spirit 3 Cellosolve Acetate 70 Using the above ink, apply it to the entire surface of a printed wiring board with exposed conductors using a screen printing machine with 180 mesh and Tetron cloth. It was dried in a hot air electric constant temperature bath for 20 minutes at 70 ° C. The surface of the obtained coating film was smooth and free of tack. Thickness was 19μm on the circuit.

Thereafter, exposure, development and post-curing were performed in the same manner as in Example 1 to manufacture a test piece.

Example 5 A photosensitive solution was prepared according to the same formulation as in Example 4 except that talc was not used in Example 4. Subsequently, the photosensitive solution was applied to a printed wiring board having an exposed conductor by a roll coater and dried in a hot air electric constant temperature bath at 70 ° C. for 20 minutes.

The surface of the obtained coating film was smooth and had no tack, and the film thickness was 17 μm on the circuit.

Thereafter, exposure, development and post-curing were performed in the same manner as in Example 1 to manufacture a test piece.

[Reference Example 3] Thiobisphenol type epoxy resin represented by the formula (2) (n≈2, epoxy value = 200, manufactured by Mitsui Toatsu Fine Co., Ltd.) in the synthesis of the half-esterified epoxy vinyl compound of Reference Example 1. ) Instead of n in equation (2),
Half-esterification epoxy vinyl compound (A-6) was carried out in the same manner as in Reference Example 1 except that a thiobisphenol type epoxy resin having an epoxy value of 190 (manufactured by Mitsui Toatsu Fine Co., Ltd.) was used. Got

Reference Example 4 Instead of the thiobisphenol type epoxy resin (n≈2, epoxy value = 200 manufactured by Mitsui Toatsu Fine Co., Ltd.) represented by the formula (2) in the synthesis of the half-esterified compound of Reference Example 1. In the formula (2), n≈4, epoxy value =
Half-esterification reaction was performed in the same manner as in Reference Example 1 except that 200 thiobisphenol type epoxy resin (manufactured by Mitsui Toatsu Fine Co., Ltd.) was used to obtain a half-esterified epoxy vinyl compound (A-7). .

Example 6 Example 1 except that the half-esterified epoxy vinyl compound (A-6) of Reference Example 3 was used in place of the half-esterified epoxy vinyl compound (A-1) in Example 1.
According to.

The surface of the obtained coating film was smooth and free of tack, and the film thickness was 200 μm on the circuit.

Example 7 Example 1 except that the half-esterified epoxy vinyl compound (A-7) of Reference Example 4 was used in place of the half-esterified epoxy vinyl compound (A-1) in Example 1.
According to.

The surface of the obtained coating film was smooth and free from tack, and the film thickness was 22 μm on the circuit.

Further, in any of Examples 2 to 7, a protective film having a highly accurate image corresponding to a negative mask was obtained as in Example 1, and the interline embedding property was also good.

Comparative Example 1 Example 1 was the same as Example 1 except that the cresol novolac type epoxy resin as the component (B-1) was not used.
The evaluation was performed according to.

 The film thickness on the circuit of the obtained coating film was 18 μm.

Comparative Example 2 All evaluations were carried out according to Example 1 except that the component (C-1) pentaerythritol triacrylate was not used in Example 1, but the exposed part swelled or partly dissolved during development, resulting in a clear image. I couldn't get a good image.

Comparative Example 3 Evaluations were made in the same manner as in Example 1 except that benzophenone as the component (D-1) and Michler's ketone as the component (D-1 ') were not used in Example 1, but the exposed portion was not exposed during development. Was almost dissolved, and image formation was impossible.

Comparative Example 4 Image formation by a conventional screen printing method was performed as follows.

That is, using a thermosetting solder resist ink S-222-G-2 manufactured by Taiyo Ink Mfg. Co., Ltd., a 300 mesh having a pattern of three pins between pins and a small diameter through hole of 0.4 mmΦ on a printed wiring board with exposed conductors, After forming an image with a screen printer with Tetoron cloth, it was heated and cured at 150 ° C. for 40 minutes in a hot air electric constant temperature bath to prepare a test piece.

Although the average thickness of the obtained coating film was 17 μm, bleeding and defective embedding between lines were observed in a part of the image.

 The above evaluation results are shown in Table-1 and Table-2.

As is clear from Table-1 and Table-2, Examples 1 to 7 of the present invention are superior to Comparative Examples 1 to 4 in pattern accuracy and have excellent performance as a solder resist. I understand.

Claims (1)

(57) [Claims] 1. A thiobisfail epoxy resin represented by the general formula (1): A half-esterified epoxidized vinyl compound obtained by reacting a reaction product obtained by ring-opening / addition of an unsaturated monobasic acid with an acid anhydride is added with (B) a mono- or polyvalent epoxy compound (C) photopolymerization A photosensitive resin composition obtained by blending a cationic unsaturated compound and (D) a photoinitiator.