JPH05188592A - Photosensitive resin composition for forming circuit pattern - Google Patents

Abstract

PURPOSE:To obtain the photosensitive resin compsn. for forming circuit patterns of an aq. alkaline soln. peeling type without having undercuts and without requiring a surface roughening treatment after peeling and removing of an etching resist film. CONSTITUTION:This compsn. is constituted by compounding a nonfunctional resin at 10 to 200 parts with 100 parts UV curing type etching resist ink consisting of a high acid value polymer having at least >=2 pieces of carboxylic acid group in one molecule, a photopolymerizable monomer having at least one piece of carboxylic (meth)acryloyl groups (signifying an acryloyl group and a methacryloyl group) and at least one piece of carboxylic acid groups in one molecule and a photopolymerizable monomer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photosensitive resin composition for forming a circuit pattern, and more specifically, it simultaneously performs formation of a circuit pattern by etching and polishing of a metal surface under an etching resist, so-called roughening treatment. The present invention relates to a photosensitive resin composition for peeling an alkaline aqueous solution for forming a circuit pattern.

[0002]

2. Description of the Related Art Conventionally, a method of forming a circuit pattern on a printed wiring board is roughly divided into a method of depositing and forming a circuit pattern on a substrate by plating, and a method of forming a circuit pattern on a metal surface of the substrate. There are two types of methods of forming a circuit pattern by forming an etching resist film of, and etching away unnecessary metal portions other than the circuit portion. Although these methods have advantages and disadvantages, all of them are well used. Among them, etching is still widely used because of its high adhesion between the circuit pattern and the printed circuit board.

The method of forming a printed circuit using etching further includes a method of printing an etching resist ink in a circuit pattern shape by a screen printing method to form an etching resist film and then etching, and further an etching resist. There is a method in which an ink is applied to the entire surface of a metal on a base material and an etching resist film is formed in a circuit pattern shape by a photographic method and then etched. However,
In this manner, when the circuit pattern etching resist film is formed in this manner, as is well known, the erosion by the etching solution is changed from the direction perpendicular to the base material as the etching progresses. Not only this, but also in the horizontal direction, there is a drawback that etching, that is, undercut, is observed in the lower part of the etching resist film. That is, FIG. 2 shows the state, and etching undercut occurs due to the etching resist film 3 formed on the copper foil 2 on the base material 1 as shown in FIG. Thus, the circuit pattern having the upper thin piece portion 6 is formed.

This undercut deteriorates the penetration of the ink when printing the solder resist ink or the plating resist ink, resulting in a decrease in the printing speed, and the blister during soldering due to the voids and the liquid during the plating treatment. This has caused diving and the like, and has caused deterioration of the performance of the solder and plating resist. Also, the upper thin section of the circuit pattern caused by undercut is
Roughening treatment on the surface of the circuit pattern before formation of the solder resist film or plating resist film results in a thin metal piece called a beard, and if this metal piece extends between circuits, it causes a short circuit, and also the printed wiring board. Was causing the performance of the.

As described above, the conventional method of forming a printed circuit by etching has not always been a satisfactory method for obtaining a highly reliable printed wiring board. Further, in the conventional method of forming a printed circuit by etching, a plating resist film or a solder resist film is used after the circuit pattern is formed in order to completely remove the etching protection film and to improve the adhesiveness of the resist. Before forming the circuit pattern, the circuit pattern is always roughened, so that not only equipment but also work efficiency and running cost are economically problematic.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above problems in the prior art. That is, an object of the present invention is to provide an alkaline aqueous solution peeling type photosensitive resin composition for circuit pattern formation, which has no undercut, and does not require surface roughening treatment after peeling and removing the etching resist film. It is in.

[0007]

Means for Solving the Problems As a result of various studies, the present inventor conducted etching by using an etching resist ink which allows an etching solution to penetrate the coating film when the coating film is formed. It was found that the above object can be achieved by carrying out the invention, and the present invention has been completed.
That is, the feature of the present invention is a high acid value polymer having at least two or more carboxylic acid groups in one molecule, and at least one (meth) acryloyl group in one molecule (meaning an acryloyl group and a methacryloyl group). And at least 1
10 to 200 parts of a non-functional resin with respect to 100 parts of a UV-curable etching resist ink composed of a photopolymerizable monomer having one carboxylic acid group and a photopolymerizable monomer.
Parts of the photosensitive resin composition for forming a circuit pattern.

The present invention will be described in detail below. The high acid value polymer used in the present invention is a styrene-maleic acid resin, an indene-maleic acid resin, a butadiene-maleic acid resin, a vinyl ether-maleic acid resin or the like maleic anhydride copolymer and a modified product thereof, or Examples thereof include carboxylic acid resins such as styrene-acrylic acid resins. As the modified product of the maleic acid copolymer, for example, 2
Examples thereof include an acrylate compound obtained by adding a monomer having at least one (meth) acryloyl group and at least one hydroxyl group in one molecule such as hydroxyethyl acrylate.

As the monomer used for modification, in addition to the above-mentioned 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate and 2-hydroxypropyl (meth) acrylate (hereinafter (meth) acrylate means acrylate and methacrylate). ), 2-hydroxybutyl (meth) acrylate, polyethylene glycol mono (meth) acrylate, polypropylene glycol mono (meth) acrylate, polycaprolactone mono (meth) acrylate, trimethylolpropane mono (meth) acrylate, trimethylolpropane di ( (Meth) acrylate, pentaerythritol tri (meth) acrylate, neopentyl glycol mono (meth) acrylate, 1,6-hexanediol mono (meth) acrylate, Serorumono (meth) acrylate, glycerol di (meth) acrylate, diethylene glycol mono (meth) acrylate, ethylene glycol mono (meth) acrylate, 2-phenoxy -2
-Hydroxypropyl (meth) acrylate and the like can be mentioned.

Further, as the carboxylic acid resin, (meth)
Acrylic acid (hereinafter (meth) acrylic acid means acrylic acid and methacrylic acid) copolymers, for example, binary copolymers such as methyl methacrylate-methacrylic acid copolymers, and styrene-2. Examples thereof include copolymers obtained by combining arbitrary (meth) acryloyl group-containing monomers such as terpolymers such as -ethylhexyl acrylate-acrylic acid copolymers.

Further, the above-mentioned hydroxyl group-containing (meth)
Acrylates such as maleic acid, phthalic acid, itaconic acid, tetrahydrophthalic acid, (methyl) hexahydrophthalic acid ((methyl) hexahydrophthalic acid means hexahydrophthalic acid and methylhexahydrophthalic acid), chlorendic acid, etc. And a copolymer of a carboxylic acid group-containing (meth) acrylate obtained by reacting with the dibasic acid anhydride and an arbitrary (meth) acryloyl group-containing monomer.

The photopolymerizable monomer in the present invention includes
Monocarboxylic acids such as (meth) acrylic acid and crotonic acid and dicarboxylic acids such as maleic acid, fumaric acid and itaconic acid, maleic acid, phthalic acid, itaconic acid, chlorendic acid, tetrahydrophthalic acid and (methyl) hexahydrophthalic acid Examples thereof include half ester compounds of acid anhydrides such as acids. The half ester compound can be obtained by reacting the above acid anhydride with the above-mentioned hydroxyl group-containing (meth) acrylate.

As the photopolymerizable monomer, in addition to the above-mentioned hydroxyl group-containing (meth) acrylate, pentaerythritol tetraacrylate, dipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate, trimethylolpropane triacrylate, diethylene glycol di ( (Meth) acrylate, monoethylene glycol di (meth) acrylate,
Alcohol-modified (meth) acrylates such as propylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate and phenyl glycidyl ether (meth) acrylate compounds, glycidyl (meth)
2-ethylhexyl (meth) in addition to glycidyl-modified ether (meth) acrylates such as acrylate-modified products and butyl glycidyl ether (meth) acrylate compounds
Examples thereof include (meth) acrylic acid esters such as acrylate, methyl (meth) acrylate, ethyl (meth) acrylate and butyl (meth) acrylate.

The non-functional resin in the present invention (which does not have photocurability, that is, has no photosensitive group)
Examples thereof include vinyl acetate polymers and copolymers such as polyvinyl acetate, vinyl acetate-crotonic acid copolymers, vinyl acetate-vinyl chloride copolymers and vinyl acetate-maleic acid copolymers. Specifically, vinyl acetate resin: Gohsenil NZ-2 (Nippon Gosei Kagaku Co., Ltd.)
And vinyl acetate resin: Gohsenil NZ-3 (manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) and the like.

In the photosensitive resin composition of the present invention, the proportion of the non-functional resin is such that the ultraviolet curable etching resist ink, that is, a high acid value polymer having at least two carboxylic acid groups in one molecule, Range of 10 to 200 parts per 100 parts of photopolymerizable monomer having at least one (meth) acryloyl group and at least one carboxylic acid group in one molecule, and photopolymerizable monomer However, it is particularly preferable to set it to 15 to 50 parts. The reason is that 20 parts of the non-functional resin is added to 100 parts of the ultraviolet curable etching resist ink.
If it is more than 0 parts, pinholes may be generated or peeling may not be possible, and if it is less than 10 parts, the surface under the protective film may not be roughened.

The composition comprising the above components includes a photopolymerization initiator, for example, benzophenones such as benzophenone and Michler's ketone; benzoin alkyl ethers such as benzoin, benzoin propyl ether and benzoin isopropyl ether; 2,2-dimethoxy. Acetophenones such as 2-phenylacetophenone, 2,2-diethoxyacetophenone and 2,2-dichloro-4-phenoxyacetophenone; 2-hydroxy-2-methylpropiophenone, 4-isopropyl-2-hydroxy-2- Propiophenones such as methylpropiophenone; Anthraquinones such as 2-ethylanthraquinone, 2-t-butylanthraquinone, 2-chloroanthraquinone; Diethylthioxanthone, Diisopropylthioxanthone, Chlorti Thioxanthones such as xanthone and the like; benzyl, 1-hydroxycyclohexyl phenyl ketone, 2-methyl - [4- (methylthio)]
2-morpholino-1-propanone, p-dimethylaminobenzoic acid ethyl ester, p-dimethylaminobenzoic acid isoamyl and the like can be added. By adding such a photopolymerization initiator, a composition having a high curing rate can be obtained.

Further, these compositions may optionally contain
Thermal polymerization inhibitors to improve storage stability, for example,
p-methoxyphenol, phenothiazine, N-nitrosophenylhydroxylamine aluminum salt (manufactured by Wako Pure Chemical Industries, Ltd., Q-1301) and the like, an adhesion improver for improving the adhesion, such as benzotriazole. In addition to thixotropic agents for improving printing, defoaming agents such as silicon, leveling agents, etc., inorganic pigments, organic pigments, coloring agents such as dyes, and inorganic fillers such as silica, talc, barium sulfate, etc. It can be added.

Furthermore, in order to adjust the composition to a suitable viscosity that is easy to apply, a solvent such as ethyl cellosolve,
It is possible to add a cellosolve solvent such as butyl cellosolve; a carbitol solvent such as carbitol acetate or butyl carbitol acetate; and an ether solvent having a high or medium boiling point such as diethylene glycol diethyl ether.

[0019]

FIG. 1 illustrates a case where a circuit pattern is formed using the photosensitive resin composition for forming a circuit pattern of the present invention. As shown in FIG. When the etching resist film 3 is formed on the copper foil 2,
Since this etching resist film has a property of allowing the etching liquid to soak while exhibiting sufficient resistance to the etching liquid, as shown in FIG. Since the circuit pattern is not directly attacked by the etching liquid from the vertical direction, the circuit pattern portion of the copper foil is sufficiently protected against the etching liquid. On the other hand, the impregnated etching solution gently etches the copper foil at the interface with the etching resist film. Therefore, by using the photosensitive resin composition of the present invention and forming an etching resist film, a circuit pattern without undercut is formed as shown in FIGS. 1 (c) and 1 (d). , The surface of the circuit pattern is also roughened at the same time to form the roughened portion 5, and the thin piece portion on the upper surface of the circuit pattern is also etched to form a circuit pattern having a gentle slope from the upper surface to the side portion. It is possible to produce favorable results.

[0020]

EXAMPLES The present invention will be specifically described below with reference to examples. In addition, "part" and "%" are expressed on a weight basis unless otherwise specified.

In carrying out the test of the present invention, the following raw materials were prepared. Synthesis of Unsaturated Double Bond-Containing Half Ester of Styrene-Maleic Acid Copolymer (Raw Material A) A styrene-maleic acid copolymer equipped with a 4-neck round bottom flask equipped with a reflux condenser, stirrer, glass stopper and thermometer. (Average molecular weight 1600, ARCO Chemical
116.9 parts of (Asia Pacific Ltd) and 192 parts of 2-hydroxyethyl methacrylate are mixed, stirred and mixed, 0.02 parts of p-methoxyphenol and 0.3 parts of 2-methylimidazole are added, and the mixture is added at 60 ° C. The reaction was continued for 8 hours to obtain a 58.5% monomer solution of an unsaturated double bond-containing partial half ester of a styrene-maleic acid copolymer having a viscosity of 285 poise. The infrared spectrophotometer confirmed the disappearance of the absorption due to the acid anhydride and the decrease of the absorption due to the hydroxyl groups in the obtained reaction product.

Synthesis of Photopolymerizable Monomer Containing Carboxyl Group (Raw Material B) A 4-neck round bottom flask was equipped with a reflux condenser, stirrer, glass stopper and thermometer, and 148 parts of phthalic anhydride, 130 parts of 2-hydroxymethacrylate and Weigh out 0.06 parts of p-methoxyphenol and, while stirring, at 90 ° C.
The reaction was continued for 10 hours to obtain a colorless transparent viscous material of a carboxyl group-containing photopolymerizable monomer having a viscosity of 41 poise.

Dissolution of Vinyl Acetate Resin with Monomer Containing Unsaturated Double Bond (Raw Material C) A three-necked round bottom flask was equipped with a reflux condenser, a stirrer and a thermometer, and vinyl acetate resin (Goshenil NZ-
2. 200 parts of Nippon Synthetic Chemical Industry Co., Ltd. and 100 parts of 2-hydroxyethyl methacrylate were weighed and 6 at 50 ° C.
After stirring for a time, a 50% solution of the unsaturated double bond-containing monomer of vinyl acetate resin having a viscosity of 335 poise was obtained. The photosensitive resin composition of the present invention was prepared using the above raw materials A, B and C by the following formulation.

Example 1 Formulation Example Raw material A 170.9 parts Raw material B 30.0 parts Raw material C 10.0 parts Benzoin isopropyl ether 5.0 parts Barium sulfate 40.0 parts Leuco crystal violet 0.4 parts

The raw material C in the formulation example of Example 1 was
30, 50, 75, 100, 300, 400
Parts and 500 parts, respectively, to be Examples 2 to 8. As comparative examples, those not using the raw material C from the formulation examples of the above-mentioned Example 1 were designated as comparative example 1, and those not using the raw materials A and B were designated as comparative example 2.

Preparation of Inks The compositions of the above Examples and Comparative Examples were mixed by stirring and then kneaded three times with a three-roll mill to obtain inks.

Preparation of Test Substrate A copper-clad laminate having a thickness of 35 μm was subjected to acid treatment and surface roughening treatment by a commonly used method, and the above ink was applied to a 150 mesh Tetoron bias screen. Printing was performed and curing was performed using an exposure device having an ultra-high pressure mercury lamp of 80 W and three lamps as a light source, and each test substrate was prepared.

Etching The etching was carried out under the conditions that the copper having a thickness of 35 μm was completely etched by using a cupric chloride acidic etching solution at a liquid temperature of 40 ° C. and applying pressure by spraying.

Peeling Removal of Hardened Etching Resist Film The hardened etching resist film was peeled off using a 4% aqueous sodium hydroxide solution at a liquid temperature of 40 ° C. and a spray pressure of 1.5 Kg / cm ² , and the peeling removal time was 30 seconds. The state of peeling at 60 seconds was observed and evaluated.

UV Curability of Ink The hardness and adhesion of the cured etching resist film were evaluated. The evaluation method is JIS K 5400 6.1.
4 (pencil scratch test) and JIS K 5400
6.15 (cross-cut test) JIS D 0202 4.1
5 (cross-cut adhesion test method).

Evaluation of etching specificity After etching, the etching cross section of the circuit pattern and 2
The remaining state of the cured etching resist film of 00 μm was observed with an optical microscope. Further, the cured etching resist film is peeled and removed, and the state of the copper surface (shape, presence or absence of pinholes) under the etching resist film is observed, and residual copper is measured by a surface roughness tester (DR100 × 11, Kosaka Seisakusho). The thickness was measured, and the decrease in copper thickness due to etching was indicated by the difference between the copper thickness before etching and the remaining copper thickness. Table 1 shows the above evaluation test results.

[0032]

[Table 1] ○ in the pinholes in Table 1 above means no pinholes,
× indicates a pinhole. In peelability, ○ means peelable, △
Indicates that some peeling remains, and x indicates that peeling is not possible.

For Example 4, the following evaluation test was further conducted. Printability In order to prove the effect of the present invention with the circuit pattern substrate (a) produced using the existing etching resist ink and the circuit pattern substrate (b) produced using the resin composition of the present invention, (a) As UVR-150G
(Taiyo Ink Mfg. Co., Ltd.) and (b) Example 4
The printability was examined using a printer. In the skip test, 100 samples were taken, and the number of sheets not skipped was examined. In the bleeding test, the number of sheets until bleeding printing was examined. Further, the thickness of the corner portion with respect to the thickness of the central portion of the conductor was measured, and the uniform covering property was evaluated by the thickness of the corner portion / the thickness of the central portion of the conductor.
The results are shown in Table 2.

[0034]

[Table 2]

[0035]

The photosensitive resin composition of the present invention exhibits sufficient resistance to an etching solution. Further, by using the photosensitive resin composition of the present invention, without forming pinholes, copper foil other than the circuit pattern portion is etched to form a circuit pattern, and at the same time, the metal surface under the etching resist film is chemically etched. Since the surface roughening treatment can be effectively performed, the generation of metal flakes that cause a short circuit is eliminated, and a highly reliable circuit board can be manufactured. In addition, since the metal surface under the etching resist film can be chemically roughened simultaneously with the formation of the circuit pattern, the roughening treatment after peeling can be omitted and the edge portion is rounded so that the edge of the ink is not broken. It is improved and printability is improved. Not only does this mean that the printing speed is increased, but the ink gets into the edges better, so blisters at the time of soldering and the penetration of liquid during plating are improved, and the reliability of the board is improved. improves.

[Brief description of drawings]

FIG. 1 is an explanatory view of a method for forming a circuit pattern using the photosensitive resin composition for forming a circuit pattern of the present invention.

FIG. 2 is an explanatory diagram of a method for forming a circuit pattern using a conventional photosensitive resin composition for forming a circuit pattern.

[Explanation of symbols]

 1 Base Material 2 Copper Foil 3 Etching Resist Film 4 Circuit Pattern 5 Roughened Area 6 Upper Thin Section

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location H05K 3/06 H 6921-4E

Claims (2)

[Claims] 1. A high acid value polymer having at least two or more carboxylic acid groups in one molecule, and a photopolymerizable polymer having at least one (meth) acryloyl group and at least one carboxylic acid group in one molecule. UV-curable etching resist ink 1 composed of monomer and photopolymerizable monomer
A photosensitive resin composition for circuit pattern formation, comprising 10 parts to 200 parts of a non-functional resin with respect to 00 parts. 2. The photosensitive resin composition for forming a circuit pattern according to claim 1, wherein the non-functional resin is a vinyl acetate polymer or copolymer.