JPH0435061B2 - - Google Patents

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a photosensitive resin composition, and more specifically, a photosensitive resin composition for forming a protective film that can be used in printed wiring board manufacturing, metal precision processing, etc. Regarding.

(Prior Art) Photosensitive resin compositions having excellent properties that can be used for solder masks, chemical plating resists, etc. have been known in the printed wiring board industry.
The main purpose of a solder mask is to limit the soldering area during soldering to prevent solder bridging, etc., to prevent corrosion of bare copper conductors, and to maintain electrical insulation between conductors over a long period of time. That's true. Usually, a solder mask (printed mask) whose main component is a thermosetting resin such as an epoxy resin or an aminoplast resin is used.

However, in recent years, the wiring density of printed wiring boards has increased, and the requirements for electrical insulation between conductors have also become stricter, and the solder masks used therein are also required to be thick and have excellent dimensional accuracy. It's getting to the point where things can no longer be dealt with.

Therefore, there is a desire for the emergence of a photosensitive resin composition that can form a thick film (25 μm on a conductor) and highly reliable solder mask with excellent dimensional accuracy using a photographic method (forming an image by imagewise exposure followed by development). There is.

Conventionally, as a photosensitive resin composition for forming a solder mask, (1) a photosensitive resin composition containing an acrylic polymer and a photopolymerizable monomer as main components (Japanese Patent Application Laid-Open No. 1983-1999-
56018, JP-A-54-1018, etc.), (2) Photosensitive resin compositions containing as main components an epoxy resin imparted with photoreactivity and an epoxy resin curing agent (JP-A-52-37996, etc.) Publications, Japanese Patent Application Laid-open No. 58-62636, etc.)
etc. are known.

However, the photosensitive resin composition of (1) above is used in ordinary film-like photosensitive materials for etching and plating (for example, Dupont's product name Riston, Hitachi Chemical Co., Ltd.'s product name FOTEK, etc.). Although it can be developed with flame-retardant 1,1,1-trichloroethane and can form high-resolution solder masks, such photosensitive resin compositions require acrylic polymers to provide film properties. Since it is used in large quantities, it has the disadvantage that the cured film does not have sufficient heat resistance.

On the other hand, the photosensitive resin composition (2) above is based on epoxy resin and has excellent heat resistance of the cured film, but is insoluble in flame-retardant organic solvents such as 1,1,1-trichloroethane. Therefore, it is necessary to use a flammable organic solvent such as cyclohexanone as a developer, which is disadvantageous in terms of safety.

(Problems to be Solved by the Invention) An object of the present invention is to eliminate the drawbacks of the prior art, to enable development with a flame-retardant developer such as 1,1,1-trichloroethane, and to improve resolution and heat resistance. Another object of the present invention is to provide a photosensitive resin composition that can form an excellent and highly reliable solder mask.

(Means for Solving the Problems) The present invention provides (a) at least one type of epoxy resin selected from the group consisting of orthocresol novolac type epoxy resin, phenol novolac type epoxy resin, and halogenated phenol novolac type epoxy resin. Isocyanato ethyl methacrylate is added to the secondary hydroxyl group of an unsaturated compound obtained by addition-reacting a novolac type epoxy resin and an unsaturated carboxylic acid at an acid equivalent/epoxy equivalent ratio in the range of 0.2 to 1. /Hydroxy group equivalent ratio is 0.2~
A photopolymerizable unsaturated compound obtained by reacting in the range of 1, (b) a linear polymer compound with a glass transition temperature of about 40 to 150°C, and (c) a sensitizer that generates free radicals by actinic light; (or) It relates to a photosensitive resin composition containing a sensitizer system.

The photosensitive resin composition of the present invention contains at least one type of essential component (a) selected from the group consisting of orthocresol novolac type epoxy resins, phenol novolac type epoxy resins, and halogenated phenol novolac type epoxy resins. Novolac type epoxy resin and unsaturated carboxylic acid,
Isocyanate ethyl methacrylate is reacted with the secondary hydroxyl group of an unsaturated compound obtained by addition reaction at an acid equivalent/epoxy equivalent ratio of 0.2 to 1 in an isocyanate equivalent/hydroxyl group equivalent ratio of 0.2 to 1. Contains a photopolymerizable unsaturated compound obtained by

The novolak-type epoxy resin used in the present invention is obtained by reacting aldehyde with orthocresol, phenol, halogenated phenol, etc. in the presence of an acid catalyst, and epichlorohydrin is added to the phenolic hydroxyl group in the presence of an alkali. It is obtained by reaction and is commercially available.

As the orthocresol novolak type epoxy resin, for example, Araldite manufactured by Ciba Geigy
ECN1299 (softening point 99℃, epoxy equivalent 230),
ECN1280 (softening point 80℃, epoxy equivalent 230),
ECN1273 (softening point 73°C, epoxy equivalent 230), EOCN104 manufactured by Nippon Kayaku Co., Ltd. (softening point 90-100°C, epoxy equivalent 225-245), EOCN103 (softening point 80-90°C, epoxy equivalent 215-235) , EOCN102 (softening point 70~80
°C, epoxy equivalent 215-235), EOCN101 (softening point
65-69°C, epoxy equivalent 205-225), etc.

Examples of phenol novolac type epoxy resins include Epicote 154 (epoxy equivalent: 176 to 181, manufactured by Shell), DEN431 (epoxy equivalent, 172 to 179), and DEN438 (epoxy equivalent, 175 to 179) manufactured by Dow Chemical.
182), YDPN-638 manufactured by Toto Kasei Co., Ltd. (epoxy equivalent
170-190), YDPN-601 (epoxy equivalent 180-
220), YDPN-602 (epoxy equivalent: 180-220), etc.

Examples of halogenated phenol novolak type epoxy resin include BREN (epoxy equivalent: 270-300, bromine content: 35-37%, softening point: 80%, manufactured by Nippon Kayaku Co., Ltd.).
Examples include brominated phenol novolak type epoxy resins such as 90°C). As the unsaturated carboxylic acid, acrylic acid, methacrylic acid, β-furylacrylic acid, β-styrylacrylic acid, α-cyanocinnamic acid, cinnamic acid, etc. are used.

In the present invention, the addition reaction between these novolac type epoxy resins and unsaturated carboxylic acids is as shown in formula (), and is carried out by a conventional method at an acid equivalent/epoxy equivalent ratio of 0.2 to 1. If the acid equivalent/epoxy equivalent ratio is less than 0.2, the photocured film is likely to swell during development treatment after image exposure. When the acid equivalent/epoxy equivalent ratio exceeds 1, adhesion, heat resistance, etc. decrease.

For example, the novolac type epoxy resin is dissolved in an inert organic solvent such as methyl ethyl ketone, methyl cellosolve acetate, ethyl cellosolve acetate, cyclohexanone, etc., and a tertiary amine such as triethylamine, tri-n-butylamine, diethylcyclohexylamine, benzyltrimethyl chloride, etc. is used as a catalyst. By stirring and reacting with the unsaturated carboxylic acid at 70 to 110°C using a quaternary ammonium salt such as ammonium or benzyltriethylammonium chloride, or hydroquinone or p-methoxyphenol as a polymerization inhibitor, the unsaturated compound is can get.

As mentioned above, the reaction of isocyanate ethyl methacrylate with the secondary hydroxyl group of the unsaturated compound obtained by the addition reaction of the novolac type epoxy resin with an unsaturated carboxylic acid is as shown in the formula (), and isocyanate equivalent / hydroxyl group equivalent. Ratio is 0.2~
1 in a conventional manner. When the isocyanate equivalent/hydroxyl group equivalent ratio is less than 0.2, 1,
Development with flame-retardant organic solvents such as 1,1-trichloroethane becomes difficult, and photocurability also decreases. If the isocyanate equivalent/hydroxyl group equivalent ratio exceeds 1, storage stability, heat resistance, etc. will decrease. As the isocyanate ethyl methacrylate, for example, one manufactured by Dow Chemical Company is used.

For example, an addition reaction is carried out between the above-mentioned novolak type epoxy resin and an unsaturated carboxylic acid, and then a urethanization catalyst such as dibutyltin dilaurate or dibutyltin di-2-ethylhexoate is added to the resulting product to form a predetermined amount of isocyanate. By stirring and reacting ethyl methacrylate at 50 to 110℃,
A photopolymerizable unsaturated compound is obtained. Under such reaction conditions, side reactions such as the reaction between urethane bonds and epoxy groups and thermal polymerization of unsaturated bonds can be prevented, and as a result, photopolymerizable unsaturated compounds can be formed without forming gel-like substances. can be obtained.

In the present invention, particularly preferred photopolymerizable unsaturated compounds include orthocresol novolac type epoxy resin/acrylic acid/isocyanatoethyl methacrylate (acid equivalent/epoxy equivalent ratio 0.2).
~1, isocyanate equivalent/hydroxyl group equivalent ratio 0.2~
1) System reactant, orthocresol novolac type epoxy resin/methacrylic acid/isocyanatoethyl methacrylate (acid equivalent/epoxy equivalent ratio 0.2
~1, isocyanate equivalent/hydroxyl group equivalent ratio 0.2~
1) system reactants, etc.

The photosensitive resin composition of the present invention contains a linear polymer compound having a glass transition temperature of about 40 to 150°C as an essential component (b).
Contained as. As this polymer compound, a known one can be used.

If the glass transition temperature is less than approximately 40℃, the heat resistance of the solder mask formed will be low, and the glass transition temperature will be approximately
If the temperature exceeds 150°C, the compatibility with the photopolymerizable unsaturated compound deteriorates, making it impossible to form a layer of the photosensitive resin composition on the support film or substrate.

The linear polymer compound is preferably a vinyl copolymer linear polymer compound in terms of compatibility with the photopolymerizable unsaturated compound and adhesion between the printed wiring board and the layer of the photosensitive resin composition. . Various vinyl monomers, such as methyl methacrylate, butyl methacrylate, ethyl acrylate, styrene, α-methylstyrene, vinyltoluene, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 2-hydroxypropyl methacrylate, are used as polymerization components for linear polymer compounds. Hydroxyethyl acrylate, acrylic acid, methacrylic acid, glycidyl methacrylate, t-butylaminoethyl methacrylate,
2,3-dibromopropyl methacrylate, 3-
Chloro-2-hydroxypropyl methacrylate, monobromophenyl acrylate, monobromophenyl methacrylate, dibromophenyl acrylate, dibromophenyl methacrylate,
Tribromophenyl acrylate, tribromophenyl methacrylate, tribromophenoxyethyl acrylate, tetrahydrofurfuryl methacrylate, tetrahydrofurfuryl methacrylate, acrylamide, acrylonitrile, and the like can be used.

The photosensitive resin composition of the present invention contains as an essential component c a sensitizer and/or a sensitizer system that generates free radicals by actinic light.

As a sensitizer, substituted or unsubstituted polynuclear quinones, such as 2-ethylanthraquinone, 2-
t-butylanthraquinone, octamethylanthraquinone, 1,2-benzanthraquinone, 2,
3-diphenylanthraquinone, etc., ketoaldonyl compounds such as diacetylbenzyl, benzoin,
α-ketaldonyl alcohols and ethers such as pivalone, α-hydrocarbon substituted aromatic acyloins such as α-phenyl-benzoin, α,α
- Aromatic ketones such as diethoxyacetophenone, benzophenone, 4,4'-bisdialkylaminobenzophenone, 2-methylthioxanthone, 2,4-diethylthioxanthone, 2-chlorothioxanthone, 2-isopropylthioxanthone, 2 - Thioxanthone such as ethylthioxanthone is used, and these may be used alone or in combination.

Examples of the sensitizer system include 2,4,5-triary, limidazole dimer and 2-mercaptobenzoquinazole, leuco crystal violet,
A combination with tris(4-diethylamino-2-methylphenyl)methane or the like is used. Also, additives which do not have photoinitiating properties by themselves but which, when used in combination with the above-mentioned substances, result in a sensitizer system with better overall photoinitiating performance, such as triethanolamine for benzophenone, etc. It is also possible to use isoamyl dimethylaminobenzoate, N-methyldietalamine, bisethylaminobenzophenone, etc. for thioxanthones.

The photosensitive resin composition of the present invention contains (a) 100 parts by weight of the above photopolymerizable unsaturated compound, (b) 5 to 400 parts by weight of the above linear polymer compound, and (c) the above-mentioned linear polymer compound. It is preferable to use the sensitizer and/or sensitizer system in a range of 0.1 to 30 parts by weight in order to form a solder mask with excellent resolution and soldering heat resistance. Furthermore, it may contain other photopolymerizable compounds. Examples of other photopolymerizable compounds include trimethylolpropane triacrylate, pentaerythritol triacrylate, and trimethylhexamethylene diisocyanate/2-hydroxyethyl acrylate (1/2 molar ratio) reaction product. Furthermore, photopolymerizable compounds disclosed in JP-A-53-56018 can also be used. However, in order to maintain heat resistance, the content of these other photopolymerizable compounds should be 10% by weight or less based on the total amount of (a) photopolymerizable unsaturated compound and (b) linear polymer compound. preferable.

Furthermore, the photosensitive resin composition of the present invention may contain other subsidiary components. As a secondary ingredient,
Examples include thermal polymerization inhibitors, dyes, pigments, fillers, coatability improvers, antifoaming agents, flame retardants, flame retardant aids, adhesion improvers, and latent curing agents for epoxy resins.

When forming a photosensitive layer using the photosensitive resin composition of the present invention, for example, the photosensitive resin composition is dissolved in an organic solvent such as methyl ethyl ketone, methyl cellosolve acetate, ethyl cellosolve acetate, cyclohexanone, etc., and this solution is dip coated. method, flow coating method, roll coating method,
A photosensitive layer with a thickness of 10 to 150 μm can be easily formed by directly coating the substrate to be processed and protected by a conventional method such as screen printing and drying the solvent.

Further, the solution is applied onto a support film such as polyethylene terephthalate film or polyimide film by a knife coating method, a roll coating method, etc., and the photosensitive element obtained by drying is heated on a substrate using a heat roll. A photosensitive layer can also be formed by laminating under pressure. In this case, the board is a printed wiring board etc. on which conductor wiring lines are formed.
When the layers have irregularities of 10 μm or more, it is preferable to laminate them under a vacuum of 200 mmHg or less in order to prevent air from being trapped. As an apparatus for this purpose, for example, a laminating apparatus described in Japanese Patent Publication No. 13341/1984 is used. In addition, when using a support film that is opaque to actinic light, it is necessary to peel off the support film at the time of exposure.

Exposure and development of the photosensitive layer thus formed are carried out by conventional methods. That is, using an ultra-high-pressure mercury lamp, high-pressure mercury lamp, etc. as a light source, directly or through a support film on the layer of the photosensitive resin composition,
Imagewise exposure through a negative mask. If the support film remains after exposure, the support film is peeled off and then developed.

The type of developer used in the development process is not particularly limited as long as it does not damage the exposed areas and selectively elutes the unexposed areas. As the developer, for example, a halogenated hydrocarbon such as 1,1,1-trichloroethane, an organic solvent/diluted alkali aqueous solution mixture such as diethylene glycol monobutyl ether sodium carbonate aqueous solution, etc. are used. It is also possible to use a cleaning agent containing 1,1,1-trichloroethane as a main component, such as Three-One EX (manufactured by Toagosei Kagaku Co., Ltd.).

The image-like protective film obtained by the above method is a corrosion-resistant film for ordinary etching, plating, etc., but after development, it can be exposed to active light and heat-treated at 80 to 200°C. A protective film with even better properties can be obtained. The order of exposure to active light and heat treatment may be in any order.

(Effects of the Invention) The protective coating obtained using the photosensitive resin composition of the present invention has sufficient resistance to organic solvents such as tricrene, methyl ethyl ketone, isopropyl alcohol, and toluene, and also to acidic or alkaline aqueous solutions. Furthermore, since it has excellent heat resistance and mechanical properties, it can be used as a permanent protective film for solder masks and the like. Furthermore, the film formed using the photosensitive resin composition of the present invention has excellent chemical and physical properties, and therefore can be used as an interlayer insulating layer of multilayer printed wiring boards, photosensitive adhesives, paints, plastic reliefs, etc. It can also be used for printing plate materials, metal precision processing materials, etc.

Further, by using the photosensitive resin composition of the present invention, it is possible to develop with a flame retardant developer such as 1,1,1-trichloroethane, and a solder mask with excellent resolution and heat resistance can be formed. Moreover, it is also possible to form a thick film solder mask using a photographic method.

(Example) Parts in the examples mean parts by weight.

Example 1 (a) Synthesis of photopolymerizable unsaturated compound A Orthocresol novolak type epoxy resin, EOCN102 (epoxy equivalent: 230) 1095 parts Methyl ethyl ketone 800 parts B Acrylic acid 343 parts Benzyltrimethylammonium chloride 7 parts p-methoxyphenol 3 Parts Methyl ethyl ketone 100 parts C Isocyanatoethyl methacrylate 737 parts Dibutyltin dilaurate 0.5 parts Methyl ethyl ketone 100 parts D Methanol 10 parts Into the reactor No. 5 which can be heated and cooled and equipped with a thermometer, a stirrer, a cooling tube and a dropper, add the above A.
was added, and the temperature was raised to 60°C while stirring to uniformly dissolve. B was added dropwise to this over about 1 hour while maintaining the reaction temperature at 60°C. After dropping B, the temperature was raised to 80°C over 2 hours, and stirring was continued at 80°C for about 20 hours to bring the acid value of the reaction system to 1 or less.

Then reduce the temperature to 60℃ and reduce the reaction temperature to 60℃
C was uniformly added dropwise over a period of about 3 hours while maintaining the temperature. After dropping C, gradually lower the reaction temperature over about 5 hours.
After raising the temperature to 80℃, lower the temperature to 60℃, and
was added, and stirring was continued for about 1 hour. Thus, a solution of a photopolymerizable unsaturated compound based on orthocresol novolak type epoxy resin with a nonvolatile content of 69%/acrylic acid/isocyanatoethyl methacrylate (acid equivalent/epoxy equivalent ratio = 1, isocyanate equivalent/hydroxyl group equivalent ratio = 1) I got ().

(b) Preparation of photosensitive resin composition 72 parts (nonvolatile content: 50 parts) of the photopolymerizable unsaturated compound solution obtained in (a), styrene/methyl methacrylate/2-hydroxyethyl methacrylate (30/63 /7 weight ratio) copolymer (molecular weight approximately 15
20 parts, glass transition temperature 100°C), 1 part of 2,4-diethylthioxanthone, 2 parts of isoamyl dimethylaminobenzoate, and Victoria Piure Blue
A solution of the photosensitive resin composition of the present invention was prepared by mixing 0.01 part.

(c) Formation of a cured film The solution of the photosensitive resin composition obtained in (b) was applied onto a copper-clad laminate, dried at room temperature for 20 minutes and at 80°C for 20 minutes, and formed into a photosensitive film with a thickness of 40 μm. formed a layer. The film was then exposed to light at 200 mJ/cm ² through a negative mask using a Phoenix Model 3000 exposure machine manufactured by Oak Seisakusho Co., Ltd.
After exposure, heat at 80℃ for 5 minutes, leave at room temperature for 30 minutes, and then heat at 20℃ using 1,1,1-trichloroethane.
Spray developed for 90 seconds. Next, using a Toshiba ultraviolet irradiation device manufactured by Toshiba Denzai Co., Ltd. (rated voltage 200V, rated power consumption 7.2KW, compatible lamp H5600L/2, number of lamps 1), irradiation was performed at 1J/cm ² and then heated to 150℃.
A solder mask with excellent dimensional accuracy comparable to a negative mask was obtained by heat treatment for 30 minutes. This solder mask has excellent thermal shock resistance and is made of rosin flux A-226 (manufactured by Tamura Kaken Co., Ltd.) for 100 min at 260°C.
Solder for 25 seconds and then solder with Triclean for 25 seconds.
After cleaning for 10 minutes at ℃, MIL-STD-
202E 107D No cracks or peeling of the coating were observed in the thermal shock test of 50 cycles under condition B (-65℃ for 30 minutes, room temperature for 5 minutes or less, 125℃ for 30 minutes), and the product has excellent long-term reliability. I found out that

Example 2 (a) Synthesis of photopolymerizable unsaturated compound A Orthocresol novolac type epoxy resin, EOCN104 (epoxy equivalent weight 230) 920 parts Halogenated phenol novolac type epoxy resin, BREN (epoxy equivalent weight 285) 285 parts Methyl cellosolve Acetate 600 parts B Acrylic acid 288 parts Henzyltrimethylammonium chloride 7 parts p-methoxyphenol 3 parts Methyl cellosolve acetate 100 parts C Ethyl isocyanate methacrylate 620 parts Dibutyl tin dilaurate 0.5 parts Methyl cellosolve acetate 100 parts D Methanol 10 parts A~ D was used, and the other procedures were the same as in Example 1-(a). Novolac type epoxy resin with nonvolatile content of 54%/acrylic acid/isocyanatoethyl methacrylate (acid equivalent/epoxy equivalent ratio = 0.8 isocyanate equivalent/hydroxyl group equivalent) A solution of a photopolymerizable unsaturated compound (ratio=1) was obtained.

(b) Preparation of photosensitive resin composition 148 parts (nonvolatile content: 80 parts) of the photopolymerizable unsaturated compound solution obtained in (a), methyl methacrylate/tribromophenyl acrylate/styrene/2-hydroxy Ethyl methacrylate (68/
10/15/7 weight ratio) copolymer (molecular weight approximately 100,000, glass transition temperature 102°C) 20 parts, benzophenone 2.7
part, Michler's ketone 0.3 parts, Hosmer M (oil and fat products)
0.1 part of an equimolar salt of phosphoric acid ester (manufactured by Co., Ltd.) and benzotriazole and 0.02 part of Bichlorapiure Blue
A solution of the photosensitive resin composition of the present invention was prepared by mixing the following parts.

Thereafter, a cured film with excellent heat resistance was obtained in the same manner as in Example 1-(c).

Further, the photosensitive resin composition was coated with a thickness of 0.8 mm.
Applied to both sides of a UL94V-0 glass epoxy flame retardant base material (MCL-E-67 manufactured by Hitachi Chemical Co., Ltd.),
When a hardened film with a thickness of 75 μm is formed,
It was found that it maintains flame retardancy of UL94V-1.

Example 3 (a) Synthesis of photopolymerizable unsaturated compound A Orthocresol novolak type epoxy resin, EOCN104 (epoxy equivalent: 230) 1095 parts Methyl cellosolve acetate 600 parts B Methacrylic acid 368 parts Benzyltrimethylammonium chloride 7 parts p-methoxy Phenol 3 parts Methyl cellosolve acetate 100 parts C Isocyanate ethyl methacrylate 287 parts Dibutyltin dilaurate 0.5 parts Methyl cellosolve acetate 100 parts D Methanol 10 parts A to D were used, and the rest was the same as in Example 1-(a). A solution ( ) of a photopolymerizable unsaturated compound based on a novolak type epoxy resin with a non-volatile content of 69%/methacrylic acid/isocyanatoethyl methacrylate (acid equivalent/epoxy equivalent ratio = 0.8 isocyanate equivalent/hydroxyl group equivalent ratio = 0.88) was obtained. .

(b) Preparation of photosensitive resin composition Instead of the photopolymerizable unsaturated compound solution (), 116 parts of the photopolymerizable unsaturated compound solution () obtained in (a) (non-volatile content: 80 parts) was added. A cured film with excellent heat resistance was obtained in the same manner as in Example 2(b) and (c).

Example 4 (a) Synthesis of photopolymerizable unsaturated compound A phenol novolac type epoxy resin,
YDPN-638 (Epoxy equivalent: 180) 857 parts Ethyl cellosolve acetate 600 parts B Cinnamic acid 176 parts Acrylic acid 86 parts Benzyltrimethylammonium chloride 7 parts p-methoxyphenol 3 parts Ethyl cellosolve acetate 100 parts C Isocyanate ethyl methacrylate 369 parts Dibutyltin dilaurate 0.1 part Ethyl cellosolve acetate 100 parts D Methanol 10 parts A to D were used, and the other procedures were the same as in Example 1-(a). NV65% phenol novolac type epoxy resin/cinnamic acid/acrylic acid /Isocyanate ethyl methacrylate (acid equivalent/epoxy equivalent ratio = 0.5, isocyanate equivalent/hydroxyl equivalent ratio = 1)
A solution () of a photopolymerizable unsaturated compound was obtained.

(b) Preparation of photosensitive resin composition 92 parts (non-volatile content: 60 parts) of the photopolymerizable unsaturated compound solution obtained in (a), methyl acrylate/
Styrene/methyl methacrylate (55/25/20 weight ratio) copolymer (molecular weight approximately 100,000, glass transition temperature 44
°C) 40 parts, 2,4-diethylthioxanthone 2
1 part, 3 parts of ethyl dimethylaminobenzoate, and 0.02 part of Victoria Pure Blue to prepare a solution of the photosensitive resin composition of the present invention.

(c) Formation of a cured film As a developer, use Three-One EX (cleaning liquid whose main component is 1,1,1-trichloroethane, manufactured by Toagosei Co., Ltd.) instead of 1,1,1-trichloroethane.
A cured film with excellent heat resistance was obtained in the same manner as in Example 1-(c).

As is clear from the examples, by using the photosensitive resin composition of the present invention, it is possible to form a thick film by a photographic method, and it is also possible to form a thick film using a flame-retardant developer such as 1,1,1-trichloroethane. Using this method, a highly reliable solder mask with excellent resolution and heat resistance can be formed.

Claims (1)

[Claims] 1 (a) At least one novolak-type epoxy resin selected from the group consisting of orthocresol novolak-type epoxy resin, phenol novolak-type epoxy resin, and halogenated phenol novolak-type epoxy resin, and an unsaturated carboxylic acid. ,
Isocyanate ethyl methacrylate is reacted with the secondary hydroxyl group of an unsaturated compound obtained by addition reaction at an acid equivalent/epoxy equivalent ratio of 0.2 to 1 in an isocyanate equivalent/hydroxyl group equivalent ratio of 0.2 to 1. a photopolymerizable unsaturated compound obtained by
(b) a linear polymer compound with a glass transition temperature of about 40 to 150°C; and (c) a photosensitive resin composition containing a sensitizer and/or a sensitizer system that generates free radicals when exposed to actinic light. thing.