JPH04294352A - Photosensitive water-base resin composition - Google Patents

Abstract

PURPOSE:To offer a photosensitive water-base resin compsn. which can be developed in an alkali aq. soln., has excellent stability, photosetting property, heat resistance, flexibility and electric characteristics, and can be used without using an org. solvent. CONSTITUTION:The reaction of an aromatic epoxy resin and unsatd. monocarboxylic acid is effected. Then the reaction with unsatd. polybasic acid anhydride is effected and the reaction product obtd. is neutralized with amines to obtain a water-dispersion resin liquid. Into this liquid, a photopolymerization initiator, thermosetting compd. and reactive diluent are incorporated to obtain the photosensitive water-base resin compsn.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a photosensitive aqueous resin composition, and more specifically, it is used in the production of printed wiring boards that have excellent ultraviolet curability and solder heat resistance, allowing images to be formed by exposure to ultraviolet light and a dilute alkali aqueous solution. The present invention relates to an aqueous resin composition used for forming a protective film.

0002

2. Description of the Related Art Printed wiring boards are commonly used to compactly incorporate electronic components. This printed wiring board is made by laminating copper foil on a laminated board and etching it according to the circuit wiring, and then electronic components are placed in predetermined locations and soldered. Solder resist is used in the pre-process of soldering electronic components to such printed wiring boards, and is a film formed on the entire surface of the circuit conductor except for the parts to be soldered. Such a film functions as an insulating film that prevents solder from adhering to unnecessary parts during soldering, and also prevents circuit conductors from being directly exposed to air and being corroded by oxidation and humidity. It also functions as a protective film.

Conventionally, such a solder resist has been formed by screen printing on a substrate and curing it with ultraviolet rays or heat. Printed circuit boards are becoming increasingly finer and more multi-layered in order to achieve higher density.
As electronic components have become more sophisticated at a remarkable pace, the mounting method for electronic components has also shifted to surface mount technology (SMT). Demand for high resolution, high precision, and high reliability for solder resists is increasing as SMT becomes finer. Regardless of whether it is a consumer-use board or an industrial board, the screen printing method is now available in a liquid form that offers excellent positional accuracy and coverage of conductor edges. A photoresist method has been proposed. For example, JP-A-50-144431 and JP-A-51-40451 disclose solder resist compositions comprising bisphenol-type epoxy acrylate, a sensitizer, an epoxy compound, an epoxy curing agent, and the like. The unexposed portions of these solder resists were removed using an organic solvent and developed. However, this removal (development) of unexposed areas using an organic solvent is problematic because it involves the use of a large amount of organic solvent, which poses risks such as environmental pollution and fire. In particular, the problem of environmental pollution has recently come under the spotlight for its effects on the human body, and the reality is that we are struggling to find countermeasures.

To solve this problem, an alkali-developable photo solder resist that can be developed with a dilute alkaline aqueous solution has been proposed. JP-A-56-40329 and JP-A-57-4578 as alkali-developable ultraviolet curing materials
No. 5 discloses a material whose base polymer is a reaction product obtained by reacting an epoxy resin with an unsaturated monocarboxylic acid and further adding a polybasic acid anhydride. Furthermore, Japanese Patent Publication No. 1-54390 discloses an active energy ray-curable resin obtained by reacting a reaction product of a novolak type epoxy resin and an unsaturated monocarboxylic acid with a saturated or unsaturated polybasic acid anhydride, and a photo-curable resin. A photocurable liquid resist ink composition that is developable with a dilute alkaline aqueous solution and includes a polymerization initiator and a diluent is disclosed.

[0005]

[Problems to be Solved by the Invention] The photosensitive resin composition based on the above-mentioned reaction product of an epoxy resin, an unsaturated monocarboxylic acid, and a polybasic acid anhydride contains 30 to 50% of an organic solvent. There are problems with its toxicity and environmental pollution. Furthermore, since a solvent-free type that does not contain an organic solvent performs exposure using a non-contact method, parallel light is required and an expensive exposure device is required. The object of the present invention is to provide an aqueous photosensitive resin composition free from the above-mentioned defects of the conventional methods.

[0006]

[Means for Solving the Problems] The present invention involves reacting an aromatic epoxy resin with an unsaturated monocarboxylic acid, and then neutralizing the reaction product obtained by reacting it with an unsaturated polybasic acid anhydride with an amine. The photosensitive aqueous resin composition is characterized in that it contains a thermosetting compound, a photopolymerization initiator, and a reactive diluent in a water-dispersed aqueous resin dispersion.

The aromatic epoxy resin of the present invention is preferably a phenol or cresol novolac type epoxy resin.

[0008] The above epoxy resin is reacted with an unsaturated monocarboxylic acid. As the unsaturated monocarboxylic acid, acrylic acid, methacrylic acid, crotonic acid, cinnamic acid, etc. are used. Acrylic acid is particularly preferred. It is preferable that 0.3 to 1.2 equivalents of this unsaturated monocarboxylic acid be reacted with respect to 1.0 equivalents of epoxy groups in the epoxy resin.

Examples of the unsaturated polybasic acid anhydride to be reacted with the reaction product of the above-mentioned epoxy resin and unsaturated monocarboxylic acid include maleic anhydride, succinic anhydride, phthalic anhydride, hexahydrophthalic anhydride, and anhydride. 3-methylhexahydrophthalic acid, 4-methylhexahydrophthalic anhydride,
3-ethylhexahydrophthalic anhydride, 4-ethylhexahydrophthalic anhydride, tetrahydrophthalic anhydride, 3-methyltetrahydrophthalic anhydride, 4-methyltetrahydrophthalic anhydride, 3-ethyltetrahydrophthalic anhydride, 4-ethyltetrahydrophthalic anhydride Ethyltetrahydrophthalic acid and the like are preferred from the viewpoint of developability and reactivity with thermosetting components. The amount of unsaturated polybasic acid anhydride used is 1.
0.4 to 1.0 equivalent is preferable with respect to 0 equivalent.

The reaction product obtained as described above is
Then, by neutralizing with amines, an aqueous resin composition in which this reaction product is dispersed in water can be obtained. The amines that can be used include primary, secondary and tertiary amines. Tertiary amines are preferred from the viewpoint of resin stability and photocurability. Examples of the tertiary amine include trimethylamine, triethylamine, tributylamine, N-methyldiethanolamine, N,N-dimethylethanolamine, N,N-diethylethanolamine, and water-soluble reactive diluents. Examples include dimethylaminoethyl acrylate, dimethylaminomethacrylate, diethylaminoethyl acrylate, diethylaminomethacrylate, and the like.

The photopolymerization initiator added to the water-dispersible resin composition of the reaction product obtained as described above is a commonly used photopolymerization initiator. For example, 4-(2
-hydroxyethoxy)phenyl-2(hydroxy-2
-propyl)ketone, p-phenylbenzophenone, benzyl dimethyl ketal, 2,4-dimethylthioxanthone, 2-isopropylthioxanthone, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, 4,4'-diethylaminobenzophenone, p-dimethylamino Examples include benzoic acid ethyl ester, which can be used alone or in combination, and 4-(2-hydroxyethoxy)phenyl-2(hydroxy-2-propyl)ketone (manufactured by Merck Japan) is particularly preferred. be.

The reactive diluent used in the present invention is used to further sufficiently photocure the reactant of the epoxy resin and the unsaturated monocarboxylic acid to obtain a coating film having water resistance, heat resistance, and alkali resistance. It is a compound that has at least two or more double bonds. For example, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate
Acrylate, polypropylene glycol di(meth)acrylate, neopentyl glycol adipate di(meth)acrylate, hydroxypivalic acid neopentyl glycol di(meth)acrylate, dicyclopentanyl di(meth)acrylate, caprolactone modified dicyclopentenyl di(meth)acrylate ) acrylate, EO-modified bisphenol A di(meth)acrylate, EO-modified phosphoric acid di(
meth)acrylate, allylated cyclohexyl di(meth)acrylate, isocyanurate di(meth)acrylate, trimethylolpropane triacrylate, dipentaerythritol tri(meth)acrylate, propionic acid modified dipentaerythritol tri(meth)acrylate, pentaerythritol Tri(meth)acrylate, PO-modified trimethylolpropane tri(meth)acrylate, tris(acryloxyethyl)isocyanurate, propionic acid-modified dipentaerythritol tetra(meth)acrylate, propionic acid-modified dipentaerythritol penta(meth)acrylate, Examples include reactive diluents such as dipentaerythritol hexa(meth)acrylate and caprolactone-modified dipentaerythritol hexa(meth)acrylate. The above difunctional, trifunctional, tetrafunctional, pentafunctional, hexafunctional, and other polyfunctional reactive diluents can be used singly or in a mixed system. This reactive diluent may be either water-soluble or water-insoluble, but water-soluble ones have better compatibility with the water-dispersible resin, and the reaction proceeds uniformly without partial reaction, resulting in a sufficient photocurable coating. is easily obtained, the sensitivity is increased, and the electrical characteristics are also good. In addition,
The amount of this reactive diluent added is 2
．． 0 to 40% (by weight) is suitable for use; if it is less, it has no effect on photosensitivity, and if it is too much, tack formation is severe and the artwork film may adhere to the substrate.

In the present invention, a thermosetting compound is added in order to obtain a sufficiently tough coating film after post-curing. Examples of this thermosetting compound include (propylene,
polypropylene) glycol diglycidyl ether, polytetramethylene glycol diglycidyl ether, 2
- ethylhexyl glycidyl ether, phenyl glycidyl ether, p-tert-butylphenyl glycidyl ether, lauryl alcohol glycidyl ether, glycerol polyglycidyl ether, trimethylolpropane polyglycidyl ether, resorcin diglycidyl ether, 1,6-hexanediol diglycidyl ether, (ethylene, propylene) glycol diglycidyl ether, sorbitol polyglycidyl ether, sorbitan polyglycidyl ether, pentaerythritol polyglycidyl ether, tris(2,3-epoxypropyl) isocyanurate, triglycidyl tris(2-hydroxyethyl) isocyanurate, etc. epoxy compounds, melamine compounds such as methylated melamine, butylated melamine, hexamethoxymethylolmelamine,
Other thermosetting compounds such as phenol compounds and polyester compounds can also be used. Although the above compounds can be used in either water-soluble or water-insoluble systems, water-soluble ones are preferable from the viewpoint of compatibility. As described above, the photosensitive aqueous resin composition of the present invention is a reaction product of an epoxy resin, an unsaturated monocarboxylic acid, and an unsaturated polybasic acid anhydride,
It consists of a reactive diluent, a thermosetting compound, and a photopolymerization initiator, and if necessary, various additives, such as inorganic pigments such as silica, alumina, talc, calcium carbonate, and barium sulfate, phthalocyanine, Organic pigments such as azo pigments, paint additives such as antifoaming agents and leveling agents, curing accelerators such as urea derivatives and imidazole derivatives, etc. can be contained.

Next, in order to explain the present invention more specifically, Examples will be given, and the effects showing the superiority of the present invention will be compared with a photosensitive resin composition lacking the requirements of the present invention. show. Note that "parts" and "%" in the examples are "parts by weight" and "% by weight."

[0015]

[Example] Production example (production of aqueous resin dispersion) a) Cresol novolac type epoxy resin (epoxy equivalent: 21
3) 243 parts were reacted with 82 parts of acrylic acid using 103 parts of carbytoluacetate as a solvent under reflux to obtain a cresol novolac type epoxy acrylate. 0.8 per 1 epoxy equivalent of this epoxy acrylate
Hexahydrophthalic anhydride to add 140 molar
The mixture was reacted under reflux until the acid value reached the theoretical value. After 340 parts of water was mixed and dispersed in this reaction product, 92 parts of triethylamine was mixed and neutralized to obtain an aqueous resin dispersion having an acid value of 35.6 and a solid content of 55.7%. b) 238 parts of a phenol novolak type epoxy resin (epoxy equivalent: 197) was reacted with 87 parts of acrylic acid using 103 parts of carbitol acetate as a solvent under reflux to obtain a phenol novolac type epoxy acrylate. 147 parts of hexahydrophthalic anhydride was added so as to add 0.8 mol per 1 epoxy equivalent of this epoxy acrylate, and the reaction was carried out under reflux until the acid value reached the theoretical value. After 327 parts of water was mixed and dispersed in this reaction product, 98 parts of triethylamine was mixed and neutralized to obtain an aqueous resin dispersion having an acid value of 37.1 and a solid content of 57.0%. c) 235 parts of bisphenol A type epoxy resin (epoxy equivalent: 187) were reacted with 90 parts of acrylic acid using 103 parts of carbitol acetate as a solvent under reflux to obtain bisphenol A type epoxy acrylate. 0 per epoxy equivalent of this epoxy acrylate.
15 of hexahydrophthalic anhydride to add 8 moles.
3 parts were added and the reaction was carried out under reflux until the acid value reached the theoretical value. After mixing and dispersing 318 parts of water in this reaction product, 101 parts of triethylamine was mixed and neutralized.
An aqueous resin dispersion having an acid value of 38.2 and a solid content of 57.9% was obtained.

Example 1 8 parts of 4-(2-hydroxyethoxy)phenyl-2(hydroxy-2-propyl)ketone was added to 100 parts of the aqueous resin dispersion (solid content 55.5%) obtained in Production Example A). 0 parts, 0.5 parts of phthalocyanine green, polyethylene glycol diacrylate (manufactured by Shin Nakamura Chemical Industry Co., Ltd.: A-20)
0) 8.0 parts, triglycidyl tris(2-hydroxyethyl) isocyanurate (manufactured by Nagase Chemical Industries, Ltd., Denacol EX-301) 8.0 parts, talc (manufactured by Fuji Talc Industries, Ltd., LMS-200) 8.0 parts A solution of the aqueous photosensitive composition was prepared by mixing and dispersing the following parts using three rolls.

Formation of Cured Coating Film The solution of the aqueous photosensitive composition obtained in Example 1 was applied to a thickness of 40 to 50 μm by screen printing onto a patterned copper-clad laminate whose surface had been previously treated. After that, it was dried for 30 minutes in a hot air circulation dryer at 80°C, and then a negative film with the desired pattern was attached to it, and an exposure amount of 100 was applied on top of it.
After irradiating with 0 mJ of ultraviolet rays, it was developed for 60 seconds with a 0.3% sodium carbonate aqueous solution, and then post-cured for 30 minutes in a hot air circulation dryer at 150° C. to obtain an aqueous solder mask. This water-based solder mask has good electrical properties, and even after 3 cycles of 10-second immersion in a 260°C solder bath using rosin-based flux A-226 (manufactured by Tamura Kaken), the paint film remains unchanged. No change was observed.

Example 2 To 100 parts of the aqueous resin dispersion (solid content 57.0%) obtained in Production Example b), 8. 0 copies,
Phthalocyanine green 0.5 parts, polyethylene glycol diacrylate 8.0 parts, triglycidyl tris (
After mixing and dispersing 8.0 parts of 2-hydroxyethyl isocyanurate and 8.0 parts of talc using three rolls, the cured coating film obtained in the same manner as in Example 1 had good soldering heat resistance and was tested. Although it was slightly inferior to Example 1, no other differences were observed in the coating film performance.

Example 3 8 parts of 4-(2-hydroxyethoxy)phenyl-2(hydroxy-2-propyl)ketone were added to 100 parts of the aqueous resin dispersion (solid content 55.5%) obtained in Production Example A). 0 copies,
Phthalocyanine green 0.5 parts, polyethylene glycol diacrylate 8.0 parts, triglycidyl tris (
2-hydroxyethyl) isocyanurate 8.0 parts, methylated melamine (Cymel 370 manufactured by Mitsui Toatsu Chemical Co., Ltd.) 4
．． After mixing and dispersing 0 part of talc and 8.0 parts of talc using three rolls, the cured coating film obtained in the same manner as in Example 1 had good solder heat resistance and had the same coating performance as that of Example 1. The above performance was obtained.

Example 4 To 100 parts of the aqueous resin dispersion obtained in Production Example a), 4-
(2-hydroxyethoxy)phenyl-2(hydroxy-2-propyl)ketone 8.0 parts, phthalocyanine green 0.5 parts, dipentaerythritol hexaacrylate 8.0 parts, triglycidyl tris(2-hydroxyethyl)isocyanurate After mixing and dispersing 8.0 parts of talc and 8.0 parts of talc using three rolls, the cured coating film obtained in the same manner as in Example 1 had slightly lower solder heat resistance and electrical properties than in Example 1. inferior.

Comparative Example 1 To 100 parts of the aqueous resin dispersion obtained in Production Example A), 4-
After mixing and dispersing 8.0 parts of (2-hydroxyethoxy)phenyl-2(hydroxy-2-propyl)ketone, 0.5 parts of phthalocyanine green, and 8.0 parts of talc using three rolls, the same procedure as in Example 1 was carried out. Although it was exposed to light and developed, peeling was observed in the coating film and the function as a solder mask could not be obtained.

Comparative Example 2 To 100 parts of the aqueous resin dispersion obtained in Production Example A), 4-
(2-hydroxyethoxy)phenyl-2(hydroxy-2-propyl)ketone 8.0 parts, phthalocyanine green 0.5 parts, triglycidyl tris(2-hydroxyethyl)isocyanurate 8.0 parts, talc 8.0 parts After mixing and dispersing with three rolls, the mixture was exposed and developed in the same manner as in Example 1, but peeling was observed in the coating film and the function as a solder mask was not obtained.

Comparative Example 3 To 100 parts of the aqueous resin dispersion obtained in Production Example A), 4-
Mix and disperse 8.0 parts of (2-hydroxyethoxy)phenyl-2(hydroxy-2-propyl)ketone, 0.5 parts of phthalocyanine green, 8.0 parts of polyethylene glycol diacrylate, and 8.0 parts of talc using a three-roll system. The cured coating film obtained in the same manner as in Example 1 was somewhat inferior in solder heat resistance compared to Example 1.

Comparative Example 4 To 100 parts of the aqueous resin dispersion obtained in Production Example A), 4-
8.0 parts of (2-hydroxyethoxy)phenyl-2(hydroxy-2-propyl)ketone, 0.5 parts of phthalocyanine green, 8.0 parts of water-insoluble reaction diluent dipentaerythritol hexaacrylate, and 8.0 parts of talc. 3
After mixing and dispersing with this roll, the cured coating film obtained in the same manner as in Example 1 was somewhat inferior in solder heat resistance and electrical properties compared to Example 1.

Comparative Example 5 8 parts of 4-(2-hydroxyethoxy)phenyl-2(hydroxy-2-propyl)ketone was added to 100 parts of the aqueous resin dispersion (solid content 57.9%) obtained in Production Example c). .0 parts, 0.5 parts of phthalocyanine green, 8.0 parts of polyethylene glycol diacrylate, 8.0 parts of triglycidyl tris(2-hydroxyethyl) isocyanurate,
After mixing and dispersing 8.0 parts of talc using three rolls, the cured coating film obtained in the same manner as in Example 1 was somewhat inferior in soldering heat resistance and electrical properties compared to Example 1.

The test method and evaluation judgment for each performance are as follows. 1) Developability test: The amount of ultraviolet rays with a wavelength of 365 nm was irradiated through the artwork film at 100 nm using an integrating light meter manufactured by Oak Seisakusho.
The test piece was irradiated with 0 mJ/cm2.
After developing with a 3% sodium carbonate developer at a spray pressure of 0.7 Kg/cm2 for 60 seconds, the state in which the unexposed areas were removed was visually determined. ◎: Completely developed. ○: There are thin areas on the surface that are not developed. Δ: Overall development remains, cracks or swelling in the coating film are observed. ×: Almost no development or cracks throughout the coating film;
Those that show swelling. 2) The same test piece as in the solder heat resistance development test was tested according to JIS. C-648
According to the test method No. 1, the state of the coating film was evaluated after a total of 1 to 3 cycles, one cycle of which was immersion in a 260° C. solder bath for 10 seconds and a peeling test using cellophane tape. ◎: No change in coating film after 3 cycles. ○: Only slightly changed after 3 cycles. △: Changed after 2 cycles. ×: Peeling occurs after one cycle. 3) Electrical properties (insulation resistance and discoloration) IPC on coating film
- Place the comb-shaped electrode of the SM-840A B-25 test coupon and test D.C. in a constant temperature and humidity chamber at 60°C and 90% RH. C
50V was applied, and insulation resistance and discoloration after 100 hours were examined. ◎: No discoloration at all. ○: Slightly discolored. △: Discolored. ×: Burnt black. 4) Sensitivity A test piece was irradiated with 1000 mJ/cm2 of ultraviolet light with a wavelength of 365 nm through a Kodak Step Tablet using an integrating photometer manufactured by Oak Manufacturing Co., Ltd., and was treated with a 0.3% sodium carbonate developer. 7Kg/c
The unremoved portion of the exposed area after developing for 60 seconds at a spray pressure of m2 is expressed in numbers. The above results are shown in Table 1. Margin below

[Table 1]

[0027]

Effects of the Invention The photosensitive aqueous resin composition of the present invention has excellent heat resistance, chemical resistance, and adhesion, and can be used not only as a solder resist, but also as a paint, a photosensitive adhesive,
It is an extremely useful composition that can be used in a wide range of applications such as plastic relief materials and printing plate materials. Furthermore, it is an industrially useful invention that has the advantage of being easily aqueous and can be used without the use of organic solvents, thereby eliminating disadvantages such as environmental pollution caused by the use of organic solvents.

Claims (4)

[Claims] [Claim 1] An aqueous resin in which an aromatic epoxy resin and an unsaturated monocarboxylic acid are reacted, and a reaction product obtained by reacting with a post-unsaturated polybasic acid anhydride is neutralized with an amine and dispersed in water. A photosensitive aqueous resin composition comprising a dispersion containing a thermosetting compound, a photopolymerization initiator, and a reactive diluent. 2. The photosensitive aqueous resin composition according to claim 1, wherein the aromatic epoxy resin is one or more of a phenol novolac type epoxy resin and a cresol novolac type epoxy resin. 3. The photosensitive aqueous resin composition according to claim 1, wherein the amine is a tertiary amine. 4. The reactive diluent is a substance having two or more double bonds in one molecule, and has a molecular weight of 2.0 to
The photosensitive aqueous resin composition according to claim 1, containing 40% by weight.