JPS63269147A - Photosensitive resin composition - Google Patents

Abstract

PURPOSE:To enable development with an alkaline aq. soln. and to obtain a solder mask having superior resolution and heat resistance by using a specified photopolymerizable unsatd. compd., a photopolymerizable monomer and a sensitizer and/or a sensitizer system which produces free radicals under active rays of light. CONSTITUTION:This photosensitive resin compsn. contains a photopolymerizable unsatd. compd. by allowing hydroxyl groups in a hydroxystyrene polymer having repeating units represented by formula I to react with isocyanatoethyl methacrylate in 0.1-0.9 ratio of isocyanato equiv. to hydroxyl equiv., a photopolymerizable monomer and a sensitizer and/or a sensitizer system which produces free radicals under active rays of light. In formula I, D is a comonomer, m is a positive number and n is 0 or a positive number. When the resin compsn. is used, an image having a large thickness and high resolution can be formed with a dil. aq. alkali soln. as a developer and a solder mask having high reliability and superior heat resistance can be formed.

Description

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

(Prior Art) It is well known that a photosensitive resin composition is used to form a resist for plating or etching in the precision processing industry, for example, in the production of printed wiring boards. Recently, photosensitive resin compositions have also been used in the field of permanent masks such as electroless plating masks and solder masks.

Since permanent masks are required to have excellent properties such as heat resistance, solvent resistance, chemical resistance, electrical properties, and mechanical properties, there are a limited number of photosensitive resins that can be used.

JP-A-52-117985, JP-A-54-101
No. 8, JP-A-53-56018, etc. disclose photosensitive resin compositions that can be used as permanent masks. However, these photosensitive resin compositions are mainly composed of polymeric binders and monomers and are not suitable for forming thick protective films. Since a molecular binder is used, when forming a photosensitive layer, the photosensitive resin composition is first uniformly melted or dispersed in an organic solvent such as toluene, methyl ethyl ketone, or methylene chloride, and then applied and dried. Therefore, if the film becomes thick, air bubbles are likely to occur during drying and the resin tends to flow, making it difficult to form a uniform protective film.

Japanese Patent Publication No. 55-127097, Japanese Patent Publication No. 49-107
No. 048 and other publications propose solvent-free photosensitive resin compositions that can be used as permanent masks.

However, since these liquid compositions use epoxy acrylate and a flammable organic solvent as a developer, they are not preferred from a safety standpoint.

(Problems to be Solved by the Invention) It is an object of the present invention to eliminate the drawbacks of the prior art, to be able to form thick films and high resolution images using a dilute alkaline aqueous developer, and to be heat resistant. An 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 is based on (a) general formula (I) (D is a comonomer, m is a positive number, n is O or a positive number, and OH is relative to the main chain. , ortho, para or meta position) isocyanate ethyl methacrylate is added to the hydroxyl group of the hydroxystyrene polymer having a repeating unit represented by
-0.9 photopolymerizable unsaturated compound obtained by reaction, (b) photopolymerizable monomer, and (c) sensitizer and/or sensitizer system that generates free radicals by actinic light. The present invention relates to a photosensitive resin composition containing the following.

The photopolymerizable unsaturated compound (a) in the present invention has the general formula (I) (D is a comonomer, m is a positive number, n is 0 or a positive number, OH is ortho, Isocyanate ethyl methacrylate is added to the hydroxyl group of a hydroxystyrene polymer having a repeating unit (taking the para or meta position) at an isocyanate equivalent/hydroxyl group equivalent ratio of 0.1.
It is obtained by reacting in the range of ~0.9.

The hydroxystyrene polymer is produced by a known method, and there are no particular limitations on the production method. For example, ortho-hydroxystyrene, meta-hydroxystyrene, or para-hydroxystyrene is polymerized by heat, radical, or cationic polymerization alone or by the above-described polymerization. It can be easily obtained by copolymerizing with comonomer D, or by copolymerizing acyloxystyrene, such as acetoxystyrene, alone or with comonomer D using a radical polymerization method, followed by hydrolysis with acid or alkali. Comonomer D does not need to be copolymerized.

The comonomer D that can be copolymerized is an unsaturated compound having a polymerizable unsaturated bond, such as styrene, α-methylstyrene, vinyltoluene, methoxystyrene, acrylonitrile, methacrylate, etc. Methacrolein, acrylic acid, methacrylic acid, acrylic esters such as methyl acrylate, methacrylic esters such as methyl methacrylate, acrylic yarns such as acrylamide, vinyl ethers such as ethyl vinyl ether, propyl vinyl ether, butyl vinyl ether, = water Examples include maleic acid, vinyl acetate, and vinylpyridine.

These hydroxystyrene polymers are commercially available, such as Resin M (poly(p-hydroxystyrene): hydroxyl equivalent: 120) manufactured by Maruzen Petrochemical Co., Ltd.
, Resin MB (brominated poly(p-hydroxystyrene): hydroxyl equivalent: approx. 246), Resin CMM (p-hydroxystyrene/methyl methacrylate copolymer: hydroxyl equivalent: 220), Resin CHM (p-hydroxystyrene/hydroxyl Ethyl methacrylate copolymer: hydroxyl equivalent: 125), resin MAA (p-hydroxystyrene/maleic anhydride copolymer: hydroxyl equivalent: 10)
9), resin MA (p-hydroxystyrene/maleic acid copolymer: hydroxyl equivalent: 80), and the like.

The reaction between the hydroxystyrene polymer and isocyanate ethyl methacrylate is carried out in a conventional manner with the isocyanate equivalent/hydroxyl group equivalent ratio in the range of 0.1 to 0.9. For example, the hydroxystyrene copolymer is dissolved in an inert organic solvent such as methyl ethyl ketone, methyl cellosolve acetate, or cyclohexanone, and dibutyl tin dilaurate, dibutyl tin di-2-ethylhexoate, etc. are added as a catalyst and as a polymerization inhibitor. , hydroquinone, p-methoxyphenol, etc., and adding isocyanate ethyl methacrylate (for example, IBM, manufactured by Dow Chemical Company), and reacting with stirring at 50 to 110°C.

If the isocyanate equivalent/hydroxyl group equivalent ratio is less than 0.1, the photocurability will be low and the exposed area will disappear during development, and if the isocyanate equivalent/hydroxyl group equivalent ratio exceeds 0.9, the substrate The adhesion with the film decreases, and development with a dilute alkaline aqueous solution becomes impossible.

After the reaction, the remaining isocyanate ethyl methacrylate is converted into urethane using a primary alcohol such as methanol, ethanol, or 2-hydroxyethyl methacrylate.
Inactivation is desirable from the viewpoint of safety and improvement of storage stability.

As the photopolymerizable monomer (b) in the present invention, known ones can be used. Preferred photopolymerizable monomers include butoxyethyl acrylate, ethylcarpitol acrylate, methyl triglycol acrylate, tetrahydrofurfuryl methacrylate, and 2-hydroxy-
Monofunctional monomers such as 3-phenoxypropyl acrylate, lauryl acrylate, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, phenoxyethyl methacrylate, cyclohexyl acrylate, trimethylolpropane, trimethylolethane, pentaerythritol, dipentaerythritol ,1
．． 3-butylene glycol, 1.4-butylene gelicol, 1.5-pentadiol, polycaprolactone diol, polypropylene glycol, decamethylene glycol, glycerin, neopentyl glycol, 2.2-
Esters of polyhydric alcohols such as bis(4,4” (2-hydroxyethoxy)phenyl)propane, tris(2-hydroxyethyl)isocyanuric acid, tripropylene glycol diacrylate, and acrylic acid or methacrylic acid, phthalic anhydride/ Diethylene glycol/acrylic acid (molar ratio I/2/2) condensate, trimethylolpropane/tetrahydrophthalic anhydride/acrylic acid (2
/1/4 molar ratio) low-molecular polyester resins having an acryloyloxy group and/or methacryloyloxy group at the end of a condensate, etc.

A reaction product of diol monoacrylate or diol monomethacrylate and diisocyanate, a reaction product of isocyanate ethyl methacrylate/water (2/1 molar ratio), etc., as described in Japanese Patent Publication No. 52-43092, etc., can also be used.

The following compounds are used as the sensitizer and/or sensitizer system (c) that generates free radicals by actinic light in the present invention.

As a sensitizer, substituted or unsubstituted polynuclear bosonones, such as 2-ethylanthraquinone, 2-[-butylanthraquinone, octamethylanthraquinone, 1,2-benzanthraquinone, 2゜3-diphenylanthraquinone, etc., diacetyl Ketoaldonyl compounds such as benzyl,
α-ketaldonyl alcohols and ethers such as benzoin and hivalone, α-hydrocarbon-substituted aromatic acyloins such as α-phenyl-benzoin, α, α-jethoxyacetophenone, etc., benzophenone, 4.41-
Aromatic ketones such as bisdialkylaminobenzophenone, thioxanthone such as 2-methylthioxanthone, 2,4-diethylthioxanthone, 2-chlorothioxanthone, 2-isopropylthioxanthone, and 2-ethylthioxanthone are used, and these can be used alone. But they can also be used in combination.

Examples of the sensitizer system include combinations of 2.4.5-triallylimidazole dimer and 2-mercaptobenzoquinazole, leuco crystal bioleft, tris(4-diethylamino-2-methylphenyl)methane, etc. 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 photoinitiating performance as a whole, such as tertiary amines such as triethanolamine for benzophenone. , isoamyl dimethylaminobenzoate, n-j tildietalamine, and sethyl aminobenzophenone for thioxanthones.

The photosensitive resin composition of the present invention contains a photopolymerizable monomer (b) based on 100 parts by weight of the photopolymerizable unsaturated compound (a).
) from 1 to 400! It is preferable to use the sensitizer and/or sensitizer system (C) in an amount of 0.1 to 30 parts by weight in order to form a solder mask with excellent resolution and soldering heat resistance.

Furthermore, the photosensitive resin composition of the present invention may contain other subsidiary components, such as a thermal polymerization inhibitor, a dye, a pigment, a polymer binder, a filler, and a coating material. Examples include properties improvers, antifoaming agents, flame retardants, flame retardant aids, adhesion improvers, and the like.

The photosensitive resin composition of the present invention can easily form a photosensitive layer with a thickness of 10 to 200 μm on a substrate to be processed and protected by a conventional method such as a roll coating method, a screen printing method, or a flow coating method. .

Further, the formation of the photosensitive layer is described in Japanese Patent Publication No. 4B-23284,
This can be carried out using a conventional coating device for liquid type photosensitive resins as shown in Japanese Patent Application Laid-open Nos. 49-43701, 46-39404, and the like.

Alternatively, the photosensitive composition of the present invention is coated on a support such as a polyester film, dried, and then brought into close contact with a substrate to be processed and protected, and the support is peeled off from the photosensitive composition to form a photosensitive layer. can also be formed.

Exposure and development of the photosensitive layer thus formed are carried out by conventional methods. That is, an ultra-high-pressure mercury lamp, a high-pressure mercury lamp, or the like is used as a light source, and imagewise exposure is performed through a negative mask.

In order to prevent resin from adhering to the negative mask, it is also possible to interpose a transparent cover film such as polyethylene terephthalate film, polypropylene film, cellulose acetate film, or polycarbonate film between the negative mask and the photosensitive resin layer. . As the cover film becomes thicker, the resolution tends to decrease, so it is desirable that the thickness be 25 μm or less.

It is also possible to perform exposure with the negative mask separated from the photosensitive layer by about 0.3 tm. After exposure, if a cover film remains, peel it off and then develop.

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, an alkaline aqueous solution such as an aqueous solution of sodium hydroxide, potassium hydroxide, or sodium carbonate is used. Furthermore, organic solvents such as methyl ethyl ketone, methyl cellosolve, and cyclohexanone can also be used.

The image-like protective film obtained by the above method has properties as a corrosion-resistant film for ordinary etching, plating, etc., but after development, it must be exposed to active light and heat treated at 80 to 200°C. By carrying out this process, the characteristics can be further improved and a permanent protective film satisfying the characteristics as a solder mask etc. can be obtained. The order of exposure to active light and heat treatment may be in any order.

(Effects of the Invention) By using the photosensitive resin composition of the present invention, it is possible to form a suldamask which can be developed with an alkaline aqueous solution and has excellent resolution and heat resistance. Furthermore, it is possible to form a thick film solder mask using a photographic method.

The protective film obtained using the photosensitive resin composition of the present invention sufficiently resists organic solvents such as tricrene, methyl ethyl ketone, isopropyl alcohol, and toluene, and also resists acidic or alkaline aqueous solutions. Furthermore, since it has excellent heat resistance and mechanical properties, it can be used as a corrosion-resistant film for etching, plating, etc., and as a permanent protective film for solder masks, etc. 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 insulating layer between the eyebrows 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.

(Example) Hereinafter, the present invention will be explained with reference to Examples. Note that the parts below mean parts by weight.

Example 1 (I) Synthesis of photopolymerizable unsaturated compound A, Poly (p-hydroxystyrene) resin M (hydroxyl equivalent: 120) 500 parts Methyl ethyl ketone 700 parts B, Isocyanatoethyl methacrylate (IBM manufactured by Dow Chemical Company)
323 parts Dibutyltin dilaurate 0.3 parts p-methoxyphenol 0.03 parts C, methanol 10 parts Heating and cooling capable 5j with thermometer, stirrer, cooling tube and dropper! Add the above component A to the reactor, and add the 6 parts while stirring.
The temperature was raised to 0°C, and the component B was uniformly added dropwise over about 3 hours while maintaining the reaction temperature at 60°C. After the dropwise addition, the reaction temperature was gradually increased to 80°C over about 5 hours. After raising the temperature to 60°C, the temperature was lowered to 60°C, the component C was added, and stirring was continued for about 1 hour. In this way, a solution of a poly(p-hydroxystyrene/isocyanatoethyl methacrylate) (isocyanate equivalent/hydroxyl group equivalent ratio -0.5) type photopolymerizable compound with a nonvolatile content of approximately 54% by weight (
I) was obtained.

(2) Solution of photopolymerizable unsaturated compound obtained in preparation of photosensitive resin composition (I) (I) 1
85 parts (non-volatile content: 100 parts), 50 parts of tripropylene glycol diacrylate, 1 part of 2,4-diethylthioxanthone, 2 parts of isoamyl dimethylaminobenzoate and 0.01 part of Victoria Vinia Blue were mixed to produce the photosensitive material of the present invention. A solution of a synthetic resin composition was prepared.

(3) Formation of a cured film The solution of the photosensitive resin composition obtained in (2) was applied onto a copper-clad laminate, dried at room temperature for 20 minutes and at 80°C for 20 minutes, and a photosensitive layer with a thickness of 40 μm was formed. was formed. The film was then exposed to light at 200 mJ/- through a negative mask using a Phoenix 3000 type exposure machine manufactured by Oak Seisakusho Co., Ltd. After exposure, the film was heated at 80°C for 5 minutes, left at room temperature for 30 minutes, and then developed using a 1% aqueous sodium hydroxide solution at 20°C for 90 seconds.
v, rated power consumption? , 2KW, compatible lamp H5600L
/2, one lamp), and after irradiating with IJ/-, heat treatment was performed at 150° C. for 30 minutes to obtain a solder mask with excellent dimensional accuracy corresponding to a negative mask.

The above solder mask has excellent cold and thermal shock resistance, and is made of rosin-based Franks A-226 (manufactured by Tamura Kaken Co., Ltd.).
Solder at ℃ for 10 seconds, then solder at 25℃ with Triclean.
, after cleaning for 10 minutes, MIL-3TD-202
E 107D Condition B (-65℃ 30 minutes, room temperature 5
In a thermal shock test of 50 cycles (within 30 minutes at 125°C), no cranking or peeling of the coating was observed, indicating that the product had excellent long-term reliability.

Example 2 (I) Synthesis of photopolymerizable unsaturated compound Example 1 (I) As component A, p-hydroxystyrene/methyl methacrylate copolymer (trade name: Resin CMM, manufactured by Maruzen Petrochemical Co., Ltd., hydroxyl equivalent: 220) 500 parts, 700 parts of methyl ethyl ketone, 282 parts of isocyanatoethyl methacrylate as component B, 0.3 part of dibutyltin dilaurate, 0.03 part of p-methoxyphenol,
The synthesis was carried out in the same manner as in Example 1 (I) except that 10 parts of methanol was used as component C, and resin CMM with a non-volatile content of about 53% by weight/isocyanate ethyl methacrylate (isocyanate equivalent/hydroxyl group equivalent ratio = 0. 8) A solution (II) of a photopolymerizable unsaturated compound was obtained.

(2) Photopolymerizable unsaturated compound solution (n) obtained in preparation of photosensitive resin composition (I) 1
89 parts (non-volatile content 100 parts), 30 parts of pentaerythritol acrylate, 1 part of 2,4-dimethylthioxanthone
1 part and 2 parts of isoamyl dimethylaminobenzoate were mixed to prepare a solution of the photosensitive resin composition of the present invention.

Thereafter, a cured film with excellent heat resistance was obtained in the same manner as in Example 1 (3).

Example 3 152 parts of the solution (I) of the photopolymerizable unsaturated compound obtained in Example 1 (100 parts of non-volatile matter), 20 parts of ditrimethylolpropane tetraacrylate, 1.4-diethyloxanthone. 5. Equimolar salt of Phosmer M (phosphate ester manufactured by Yushi Products Co., Ltd.) and benzotriazole 0.
1 part, Simbon (ultrafine talc manufactured by Nippon Talc Co., Ltd.) 30
1 part and 0.5 part of phthalocyanine green were kneaded using three rolls to prepare a solution of the photosensitive resin composition of the present invention. Thereafter, a cured film with excellent heat resistance was obtained in the same manner as in Example 1 (3).

Example 4 Example 1 As component A of (I), p-hydroxystyrene/hydroxyethyl methacrylate copolymer (trade name Resin C, manufactured by Kuzen Petrochemical Co., Ltd.) (M, hydroxyl equivalent: 125
), 700 parts of methyl ethyl ketone, 310 parts of isocyanatoethyl methacrylate as component B, 0.3 part of dibutyltin dilaurate, 0.03 part of p-methoxyphenol, 10 parts of methanol as component C,
The rest was the same as in Example 1 (I), and the nonvolatile content was about 5.
3% by weight of resin CHM/isocyanate ethyl methacrylate (isocyanate equivalent/hydroxyl group equivalent ratio -O,S
A solution (III) of a photopolymerizable unsaturated compound was obtained.

(2) Preparation of photosensitive resin composition (I) Solution of photopolymerizable unsaturated compound obtained in (II)
I) 189 parts (non-volatile content: 100 parts), 30 parts of tripropylene glycol diacrylate, 2 parts of 2,4-diethylthioxanthone and 3 parts of ethyl dimethylaminobenzoate.
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 (3).

Claims (1)

[Claims] 1. (a) General formula (I) ▲ Numerical formulas, chemical formulas, tables, etc. ▼ (I) (D is a comonomer, m is a positive number, n is 0 or a positive number, Isocyanate ethyl methacrylate is added to the hydroxyl group of a hydroxystyrene polymer having a repeating unit represented by (OH takes the ortho, para or meta position with respect to the main chain) at an isocyanate equivalent/hydroxyl group equivalent ratio of 0.1.
-0.9 photopolymerizable unsaturated compound obtained by reaction, (b) photopolymerizable monomer, and (c) sensitizer and/or sensitizer system that generates free radicals by actinic light. A photosensitive resin composition containing.