JPH04329543A - Composition of electrodeposition coating material for forming photoresist film - Google Patents

Abstract

PURPOSE:To obtain the compsn. which has excellent storage stability and can form a photoresist film having a high contrast between exposed parts and unexposed parts even after long-term storage by incorporating a spiropyran compd. having a photochromism characteristic into the compsn. CONSTITUTION:The spiropyran compd. having the photochromism characteristic to be used is a piran deriv. having a spiro atom. While any spiropyran compds. which color and decolor by irradiation with active energy rays, the compd. which colors is more preferable in terms of the possession of a more distinct identification ability. The compd. which is colorless or nearly colorless before the irradiation with the active energy rays and discolors to dark blue, purple or reddish purple, etc., after the irradiation to facilitate the identification of the exposed parts and the unexposed parts is more preferable. The more preferable examples of the spiropyran compd. are an indolino spiropyran compd., benzothiazolinospiropyran compd., oxazine spiropyran compd., etc.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to an electrodeposition coating composition for forming a photoresist film (hereinafter also simply referred to as electrodeposition coating composition), and more specifically, the present invention relates to an electrodeposition coating composition for forming a photoresist film (hereinafter simply referred to as electrodeposition coating composition). The electrodeposition coating composition is capable of developing or decoloring, is capable of distinguishing exposed areas and unexposed areas with high contrast, and is capable of forming a photoresist film with high discrimination ability even after the coating composition is stored for a long period of time. It is about things.

0002

[Prior Art] Most printed wiring boards are made by laminating a photosensitive film on the surface of a laminate covered with copper foil (hereinafter abbreviated as "copper-clad laminate"), and then exposing and developing a photographic negative film. After forming an etching resist film, unnecessary copper foil other than the circuit pattern is removed by etching.
After that, the etching resist film is removed.

[0003] The photosensitive film used in this method contains a leuco dye, which is a color-forming dye, so that the exposed area becomes colored by irradiation with active energy rays, making it easy to confirm whether the exposure process has been completed. It is common to do so. By including a chromogenic dye in this way, the photosensitive film may be removed even though it has not been exposed and no circuit pattern has been formed by proceeding to the next development process, or the photosensitive film may be removed even though it has not been exposed to light and no circuit pattern has been formed. This prevents erroneous operations that would result in double exposure, even though the

On the other hand, as a method that does not use the above-mentioned photosensitive film, there is a method of forming a photosensitive coating film by electrodeposition, and this method also uses leuco dye (reduced dye) in the photosensitive electrodeposition paint bath. ) has been proposed (Japanese Unexamined Patent Application Publication No. 2003-1990)
249296).

[0005]

[Problems to be Solved by the Invention] Leuco dyes blended into electrodeposition paints as coloring dyes for photoresist films are
It develops a fairly clear color after exposure to active energy rays, imparts sufficient contrast to the photoresist film, and does not have a practical negative effect on the photosensitivity of the photoresist film. Furthermore, there are no particular problems when preparing the electrodeposition paint, and leuco dyes are used as excellent coloring dyes.

However, once an electrodeposition paint containing a leuco dye is prepared, it develops color in a short period of time even if it is stored in a dark place at room temperature. When a photoresist film is formed on a copper-clad laminate using this colored electrodeposition paint, the contrast between the exposed and unexposed areas is very poor during the exposure process, making it difficult to confirm whether there has been exposure or not. The purpose of preventing exposure to light could not be fully achieved. It was assumed that the cause of this was that the almost colorless reduced leuco dye was oxidized by dissolved oxygen in the electrodeposition paint and developed color. I tried to prevent it, but
Addition of an antioxidant was of no practical use, as the progress of color development was only slightly delayed. The present invention provides an electrodeposition coating composition for forming a photoresist film that has excellent storage stability and is capable of forming a photoresist film with high contrast between exposed and unexposed areas even after long-term storage. It is something to do.

[0007]

[Means for Solving the Problems] As a result of intensive studies to solve the above problems, it has been found that when a spiropyran compound having photochromic properties is used, the electrodeposition paint does not develop or discolor for a long period of time during storage, and The present inventors have discovered that after irradiation with active energy rays, it is possible to form a high-contrast photoresist film in which exposed areas and unexposed areas can be easily distinguished, and the present invention has been completed. That is, the present invention is an electrodeposition coating composition for forming a photoresist film, which is characterized by containing a spiropyran compound having photochromic properties.

The present invention will be explained in more detail below. There are anionic and cationic types of electrodeposition paints, and there are negative and positive types of photoresist films, so there are four types of electrodeposition paints depending on the combination of the two types. The spiropyran compound according to the present invention can be used in any of the above-mentioned four types of conventionally used electrodeposition paints. As an electrodeposition paint containing a spiropyran compound, for example, JP-A-2-2492
In addition to the compositions described in Publication No. 96 (see page 2, upper right column, line 18 to page 4, lower left column, line 17), any conventionally used compositions can be used, and more specific Examples include the following electrodeposition paints.

[0009] Negative anionic electrodeposition paints are water-soluble or water-dispersible, have film-forming properties, and have anionic properties.
It consists of a water-soluble or water-dispersible photocurable composition containing a polymerizable unsaturated resin that can be polymerized by irradiation with active energy rays and a water-insoluble photopolymerization initiator, and the polymerizable unsaturated resin is , an acid value of 20 to 300, an unsaturation equivalent of about 150 to 3000, and a number average molecular weight of about 30.
0 to 300,000 is preferred.

Examples of resins constituting the basic skeleton of the polymerizable unsaturated resin include acrylic resin, urethane resin, epoxy resin, polyester resin, polyether resin, alkyd resin, polyvinyl chloride resin, fluororesin, silicone resin, and acetic acid resin. There are vinyl resins, polyvinyl alcohol, etc., and polymerizable unsaturated resins include monomers with acidic groups such as carboxyl groups and monomers with ethylenically unsaturated groups such as acryloyl or methacryloyl groups in the basic skeleton of these resins. It incorporates the body as a component.

Negative cationic electrodeposition paints are composed of a water-soluble or water-dispersible photocurable composition containing a polymerizable unsaturated resin and a water-insoluble photopolymerization initiator. The saturated resin has the same basic skeleton as the polymerizable unsaturated resin in the above-mentioned negative anionic electrodeposition paint, and in this basic skeleton, a monomer having a basic group such as an amino group and an acryloyl group or a methacryloyl group. This is a known resin that incorporates a monomer having an ethylenically unsaturated group such as

[0012] As the water-insoluble photopolymerization initiator to be added to the negative electrodeposition paint, any conventionally used initiator can be used, specifically benzoin, benzoin methyl ether, benzyl, diphenyl disulfide, Eosin, thionine, diacetyl, Michler's ketone, anthraquinone, etc. are used in an amount of 0.1 per 100 parts by weight (hereinafter simply referred to as parts) of the non-volatile content of the electrodeposition paint.
It is preferable to set it as the range of -10 parts.

[0013] As the positive electrodeposition coating material, a known one containing as a main component a water-soluble or water-dispersible resin having a quinonediazide group such as a benzoquinonediazide group or a naphthoquinonediazide group can be used.

Specific examples of water-soluble or water-dispersible resins that can be used as positive-type anionic electrodeposition paints include resins obtained by an esterification reaction between hydroxyl groups of unsaturated monomers and acid groups of naphthoquinonediazide sulfonic acid. There are resins made by copolymerizing unsaturated monomers with other unsaturated monomers having acidic groups such as carboxyl groups, and water-soluble or water-dispersible resins that can be used as positive-type cationic electrodeposition paints. As a specific example of There are resins copolymerized with unsaturated monomers.

The spiropyran compound having photochromic properties used in the present invention is a pyran derivative having a spiro atom, and one example thereof is a cyclic compound having the structure shown below. These compounds have the property of ring-opening and developing or decoloring when irradiated with active energy rays, and are not easily affected by oxidation such as dissolved oxygen in the electrodeposition paint, so the electrodeposition paint can be used for a long period of time. It exhibits excellent discrimination ability even after storage.

[0016]

[Chemical formula 1]

[0017] As the spiropyran compound used in the present invention, both those that develop color and those that discolor when irradiated with active energy rays can be used, but compounds that develop color are preferred because they have a clearer discrimination ability. It is more preferable that the material is colorless or almost colorless before irradiation with active energy rays, and develops a deep blue, purple, or reddish-purple color after irradiation, so that exposed areas and unexposed areas can be easily distinguished. Preferred specific examples of spiropyran compounds include indolinospiropyran compounds, benzothiazolinospiropyran compounds, oxazine spiropyran compounds, etc. Among these compounds, indolinospiropyran compounds are more preferable, especially those with nitro group. , a long-chain alkyl group, a spiropyran compound having a heterocycle having a nitrogen atom or a sulfur atom as a constituent atom is preferred. Specific examples of spiropyran compounds are illustrated below.

Examples of indolinospiropyran compounds include 1,3,3-trimethyl-6'-hydroxyspiro[
2'H-1'-benzopyran-2,2'-indoline]
, 1,3,3-trimethyl-6'-nitrospiro[2'
H-1'-benzopyran-2,2'-indoline], 1
,3,3-trimethyl-8'-methoxyspiro[2'H
-1'-benzopyran-2,2'-indoline], 1,
3,3-trimethyl-6'-nitro-8'-methoxyspiro[2'H-1'-benzopyran-2,2'-indoline], 1,3,3-trimethyl-5-methylsulfonyl-6'- Nitro-8'-methoxyspiro[2'H-1
'-benzopyran-2,2'-indoline], 1-n-
Butyl-3,3-dimethyl-5-methylsulfonyl-6
'-Nitro-8'-methoxyspiro[2'H-1'-benzopyran-2,2'-indoline], 1-n-hexadecyl-3,3-dimethyl-6'-nitro-8'-n-
dodecanoyloxymethylspiro[2'H-1'-benzopyran-2,2'-indoline], 1-n-octadecyl-3,3-dimethyl-6'-nitro-8'-n-docosanoyloxyspiro[ 2'H-1'-benzopyran-2,2'-indoline], 1-n-octadecyl-3
,3-dimethyl-6'-nitro-8'-n-dodecanoyloxymethylspiro[2'H-1'-benzopyran-
2,2'-indoline], 1,3,3-trimethyl-6
'-Nitro-8'-n-docosanoyloxymethylspiro[2'H-1'-benzopyran-2,2'-indoline], 1-n-octadecyl-3,3-dimethyl-6'
-Nitro-8'-n-docosanoyloxymethylspiro[2'H-1'-benzopyran-2,2'-indoline], 1-n-octadecyl-3,3-dimethyl-6'-
Nitro-8'-n-triacontanoyloxymethylspiro[2'H-1'-benzopyran-2,2'-indoline], 1,3,3-trimethyl-6'-nitrospiro[2'H-1'-benzothiopyran-2,2'-indoline],1-n-hexyl-3,3-dimethyl-6'-
Nitro-8'-methoxyspiro[2'H-1'-benzothiopyran-2,2'-indoline],1,3,3-trimethyl-5-methoxy-6'-nitro-8'-chlorospiro[2'H-1'-Benzothiopyran-2,2'-
indoline], 1,3,3-trimethyl-5,7-dimethoxy-6'-nitro-8'-methoxyspiro[2'H
-1'-benzothiopyran-2,2'-indoline] and 1,3,3-trimethyl-5-dimethylamino-6'
-Nitrospiro[2'H-1'-benzothiopyran-2
, 2'-indoline], etc.

As a benzothiazolinospiropyran compound, 3-methyl-3',8'-dimethoxy-6'-nitrospiro[2'H-1'-benzopyran-2,2'-
benzothiazoline], 3-ethyl-3',8'-dimethoxy-6'-nitrospiro[2'H-1'-benzopyran-2,2'-benzothiazoline], 3-methyl-3'
-ethoxy-6'-nitro-8'-methoxyspiro[2
'H-1'-benzopyran-2,2'-benzothiazoline], 3-methyl-3'-phenoxy-6'-nitro-
8'-methoxyspiro[2'H-1'-benzopyran-
2,2'-benzothiazoline] and the like.

As an oxazine spiropyran compound,
Examples include 1,3,3-trimethylindolinonaphthospirooxazine.

The preferred amount of the spiropyran compound to be added is as follows:
The amount is 0.1 to 10 parts per 100 parts of nonvolatile components in the electrodeposition paint. If it is less than 0.1 part, the color development upon exposure will not be sufficient and the contrast will be poor. On the other hand, if the amount exceeds 10 parts, photosensitivity decreases and costs increase.

The spiropyran compound according to the present invention may be used alone, but dyes such as malachite green, acid magenta, methyl violet, ethyl violet, Victoria green, and Victoria blue may also be used in combination to enhance the contrast. can.

[0023] The blending ratio of the above dyes may be determined according to a conventional method.
For example, 50 parts or less of each may be blended per 100 parts of the spiropyran compound.

To prepare the electrodeposition coating composition of the present invention,
The above components may be mixed according to a conventional method, but instead of directly blending the spiropyran compound with other components, first mix ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, It is preferable to use it after dissolving it in a solvent such as diethylene glycol dimethyl ether, ethyl carbitol acetate, and butyl carbitol acetate.

Using the electrodeposition coating composition according to the present invention thus obtained, a photoresist film can be formed on, for example, a copper-clad laminate by a conventional electrodeposition process, followed by drying, exposure, development, and the like by conventional methods. A desired printed wiring board can be obtained through the etching and film removal steps.

[0026]

[Examples] The present invention will now be explained in more detail with reference to Examples and Comparative Examples. Example 1 A mixed solution consisting of 45 parts of methyl methacrylate, 20 parts of isobutyl acrylate, 15 parts of hydroxyethyl methacrylate, 20 parts of acrylic acid, and 2 parts of azobisisobutyronitrile was prepared using isopropyl alcohol, which was maintained at a temperature of 80°C under a nitrogen atmosphere. The solution was added dropwise to 110 parts over 5 hours. Thereafter, the mixture was aged for 1 hour, and 0.5 parts of azobisisobutyronitrile and 10 parts of isopropyl alcohol were added and aged for 2 hours to synthesize a high acid value acrylic resin solution.

While blowing air into this high acid value acrylic resin solution, 20 parts of glycidyl methacrylate, 0.7 parts of dimethylbenzylamine as a catalyst, and 0.15 parts of phenothiazine were added and reacted at a temperature of 80°C for 12 hours to form a high acid. A photosensitive resin solution was obtained. The weight of nonvolatile components in this high acid value photosensitive resin solution was 50%, the acid value was 74, the weight average molecular weight of the high acid value photosensitive resin was 38,000, and the unsaturated equivalent was 1 mol/Kg.

To 138 parts of this high acid value acrylic resin solution,
Trimethylolpropane triacrylate 33 parts, 1,
3,3-trimethyl-6'-nitrospiro[2'H-1
5% by weight of '-benzopyran-2,2'-indoline]
20 parts of butyl carbitol acetate solution (1,3,3
The content of -trimethyl-6'-nitrospiro[2'H-1'-benzopyran-2,2'-indoline] is 1% based on the weight of non-volatile components) and as a photoinitiator Irgacure 907 (manufactured by Ciba Geigy: Add 5 parts of α-aminoacetophenone) and mix thoroughly, then add 6 parts of triethylamine to thoroughly neutralize, until the weight of non-volatile components is 10
% of deionized water to obtain a negative anionic electrodeposition paint (pH 7.2). The color of the paint was light red.

Using this electrodeposition paint, a copper clad laminate for printed wiring boards (40 x 150 x 1.6 mm) was used as an anode, the paint temperature was set at 25°C, and the current value was set at a current density of 60 mA/dm2. Electrodeposition coating was performed by applying electricity for 3 minutes.

After electrodeposition, the copper-clad laminate with the deposited coating was washed with water, air-dried with an air knife, and then heated and dried at 100°C for 5 minutes to form a smooth photoresist with a thickness of 17 μm without stickiness. A membrane was obtained.

Next, a wiring pattern film was adhered onto this photoresist film using a vacuum device, and exposure was performed using a 3 KW ultra-high pressure mercury lamp at an irradiation dose of 100 mJ/cm 2 .

When the pattern film was removed after exposure, the exposed area developed a deep and clear reddish-purple color, while the unexposed area remained almost colorless, as before exposure, and the wiring pattern could be clearly identified. there were.

Subsequently, after development with a 1% sodium carbonate aqueous solution, etching was performed with a ferric chloride aqueous solution, and further 10%
% sodium hydroxide aqueous solution to remove the remaining resist film.
A printed wiring board having a desired wiring pattern was obtained.

[0034] Further, exposure was carried out with the irradiation dose lowered to 50 mJ/cm2, and sufficient color development was obtained even at 50 mJ/cm2.

The electrodeposition paint used here was stored at room temperature, and after one week, two weeks, and one month, the same electrodeposition operation was carried out to determine whether or not the electrodeposition paint developed color and the color development of the exposed area. was evaluated. At any point in time, the color of the electrodeposition paint did not change from the initial color, and the color development of the exposed area was very good, showing the same high contrast as the initial color. The steps after development were also able to be carried out without any problems.

Example 2 1,3,3-trimethyl-6'-nitrospiro [2'H-1'-benzopyran-2,2'-indoline] used in Example 1 was replaced with 1,3,3- Trimethyl-8'-
Methoxyspiro[2'H-1'-benzopyran-2,2
'-indoline], the same evaluation as in Example 1 was performed. The results are shown in Table 1 below.

Example 3 In place of 1,3,3-trimethyl-6'-nitrospiro[2'H-1'-benzopyran-2,2'-indoline] used in Example 1, 1,3,3- Trimethyl-6'-
Nitro-8'-n-docosanoyloxymethyl spiro [
2'H-1'-benzopyran-2,2'-indoline]
The same evaluation as in Example 1 was performed using the following. The results are shown in Table 1 below.

Comparative Example 1 Leuco crystal violet was used in place of 1,3,3-trimethyl-6'-nitrospiro[2'H-1'-benzopyran-2,2'-indoline] used in Example 1. , the same evaluation as in Example 1 was performed. As a result, in the photoresist film obtained by electrodeposition coating immediately after preparing the electrodeposition paint, the exposed areas developed a bluish-purple color after exposure, and were sufficiently distinguishable from the almost colorless unexposed areas. there were.

However, while the electrodeposition paint used here was stored in a dark place at room temperature, it gradually began to develop a blue color, and one week after preparing the electrodeposition paint, it became impossible to distinguish between exposed and unexposed areas. It has become difficult to obtain high photoresist films. These results are also shown in Table 1 below.

[0040]

[Table 1]

[0041]

[Effects of the Invention] The electrodeposition coating composition of the present invention can be stored stably for a long period of time, and can form a photoresist film with high contrast for a long period of time after preparing the electrodeposition coating composition. be. Therefore, the composition of the present invention can retain the effect of confirming the presence or absence of exposure and preventing double exposure for a long period of time, and therefore can significantly extend the period of use of electrodeposition paints, which has great practical advantages. It has the following.

Claims (1)

[Claims] 1. An electrodeposition coating composition for forming a photoresist film, comprising a spiropyran compound having photochromic properties.