JPH04311775A - Positive-type photo-sensitive anionic electrodeposition coating resin composition, electrodeposition bath and electrodeposition method using the same - Google Patents

Abstract

PURPOSE:To obtain the subject composition capable of forming a photo-resist having good residual film ratio and storage stability and excellent photosensitive characteristics and mechanical properties by compounding a specific base- neutralized (meth)acrylic resin with a photo-sensitive agent consisting of two specific kinds of compounds. CONSTITUTION:The objective composition is produced by compounding (A) a resin produced by copolymerizing (meth)acrylic acid and a polymerizable monomer giving a homopolymer having a glass-transition point of <=0 deg.C as essential monomer components and neutralizing the obtained (meth)acrylic resin having an acid value of 30-250 with a base and (B) a photo-sensitive agent consisting of (i) a compound of formula I (R<1> is alkyl; R<2> is H, alkyl, alkoxy or nitro; R<3> is group of formula II to IV; m is 0, 1 or 2; n is 1, 2 or 3; m-l-n is 1, 2 or 3) and (ii) a compound of formula V (R<4> is alkyl; R<5> is H, alkyl, alkoxy or nitro; R<6> is group of formula VI to formula VIII; s is 0, 1 or 2; t is 1, 2 or 3; s+t is 1, 2 or 3).

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a positive photosensitive anionic electrodeposition coating resin composition used for forming resist patterns in the manufacture of printed wiring boards, an electrodeposition coating bath using the same, and an electrodeposition coating method. Regarding.

0002

2. Description of the Related Art Conventionally, as a method of forming a resist pattern on the surface of a substrate, a method is often used in which a photosensitive layer is formed on the surface of the substrate, then irradiated with actinic rays, and then developed. Various methods are employed for forming the photosensitive layer in this step. For example, methods using a photosensitive resin composition (coating liquid) such as dip coating, roll coating, and curtain coating, or methods in which a photosensitive layer is preformed on a substrate (
A method is known in which a photosensitive film (hereinafter abbreviated as photosensitive film) is laminated on the surface of a substrate using a laminator or the like. Among these methods, the method using a photosensitive film is currently being adopted as the mainstream method, particularly in the field of printed wiring board manufacturing, because it can easily form a photosensitive layer with a uniform thickness.

[0003]Recently, as printed wiring boards have become more dense and precise, resist patterns of higher quality have become necessary. That is, it is desired that the resist pattern be free of pinholes and that is in close contact with the surface of the underlying substrate. It is known that the currently mainstream method of laminating photosensitive films has limitations in meeting such demands. With this method, dents during board manufacturing,
It is difficult to follow the unevenness of the substrate surface caused by non-uniform polishing, the mesh of cloth in the inner layer of the substrate, non-uniform copper plating on the surface, etc., and it is difficult to obtain sufficient adhesion. This difficulty can be avoided to some extent by laminating the photosensitive films under reduced pressure (see Japanese Patent Publication No. 59-3740), but this requires special and expensive equipment.

For these reasons, solution coating methods such as dip coating, roll coating, and curtain coating have been reconsidered in recent years. However, these coating methods have problems such as difficulty in controlling the film thickness, insufficient uniformity of the film thickness, and occurrence of pinholes.

[0005]Recently, a new method of forming a photoresist film by electrodeposition coating has been proposed (Japanese Patent Application Laid-Open No. 6-119)
2-235496). According to this method, ■
Improves resist adhesion, ■Good ability to follow irregularities on the substrate surface, ■Can form a photoresist film with uniform thickness in a short time, ■As the coating liquid is an aqueous solution, it prevents contamination of the working environment. It has the advantage of not causing any problems in terms of disaster prevention.

[0006] In particular, several proposals have been made in the past regarding positive type photosensitive electrodeposition paints that are considered to be effective in manufacturing printed wiring boards having through holes. Most of them are of the type in which a photosensitive group such as 1,2-naphthoquinonediazide is introduced into the polymer molecule (for example, JP-A-61
-206293, JP-A No. 63-221177, JP-A No. 64-4972), there are advantages in terms of electrodeposition coating, such as easy control of the electrodeposition solution, but on the other hand, positive From the viewpoint of type photoresists, there were problems such as insufficient photosensitivity, low mechanical strength of the film, and difficulty in finely adjusting various properties.

On the other hand, when forming a positive photoresist by a solution coating method used in the manufacturing process of semiconductor devices such as ICs and LSIs, most of the composition of the positive photoresist used is novolak resin, vinyl, etc. It is a mixture of an alkali-soluble resin such as a phenol resin and a photosensitizer represented by an ester compound of benzophenone having two or more hydroxyl groups and 1,2-naphthoquinonediazide sulfonic acid (for example, 6
3-305348, JP-A-63-279246, JP-A-64-11259, JP-A-64-17049). From the viewpoint of performance as a positive photoresist, these resins have good photosensitivity and mechanical properties of the resist film, but naturally, these resins do not contain carboxyl groups, which are essential for anionic electrodeposition paints. However, it cannot be used as an electrodeposition paint as it is.

Furthermore, the resin that is the main component of the photoresist used in the manufacture of printed wiring boards, which is the main application of the present invention, has traditionally been a (meth)acrylic resin [(meth)acrylic resin] due to its physical properties and ease of handling. , shall mean methacrylic and acrylic. The same applies hereafter] has been generally used, but benzophenone having two or more hydroxy groups, which is commonly used as a photosensitizer, and
, 2-naphthoquinonediazide sulfonic acid has extremely poor compatibility with (meth)acrylic resin, and therefore cannot be used in combination with (meth)acrylic resin as the main component of a photosensitizer.

[0009] Furthermore, a method has been proposed in which a positive photoresist is formed by applying a coating liquid containing a mixture of an acrylic resin having a carboxyl group and a photosensitizer (Japanese Patent Publication No. 1983-1999).
14042). However, the naphthoquinonediazide sulfonic acid ester of p-cumylphenol, which is frequently used in the examples described in this publication, is not as effective as the ester compound of polyhydroxybenzophenone and 1,2-naphthoquinonediazide sulfonic acid. However, the compatibility with acrylic resins is not sufficient, and the photosensitivity of the composition is also low.

In addition, as a post-exposure developer suitable for resists having this composition, an alkanolamine aqueous solution or a solution containing both amine and alcohol is suitable, and an alkaline developer is not suitable. However, most of the developers used in the tenting method using photosensitive film, which is the mainstream manufacturing method for printed wiring boards at present, mostly use alkali; Even in this case, it goes without saying that it is desirable to use an alkali developer that follows the current method. In this sense, it can be said that this composition has no versatility.

Furthermore, even though this composition has carboxyl groups in the resin, it cannot be used as an electrodeposition paint as it is. This is because, in the case of electrodeposition paints, a film cannot be formed after electrodeposition unless the glass transition point of the film after electrodeposition is low, or in other words, the minimum film forming temperature is not low. Therefore, acrylic resins naturally require a monomer composition that takes this point into consideration.

[0012] A positive type photosensitive electrodeposition paint resin composition that solves these problems has also been proposed (Japanese Patent Application No. 1-238).
434, Japanese Patent Application No. 2-46853), the composition consisting of a combination of an ester compound of gallic acid ester and 1,2-naphthoquinonediazide sulfonic acid and (meth)acrylic resin also has good compatibility. However, if left for a long period of time, there were problems such as a decrease in sensitivity and the formation of precipitates, and the rate of residual film after development was not high.

As mentioned above, the positive photoresist compositions formed by electrodeposition coating that have been proposed to date have low photosensitivity and mechanical strength of the film, and furthermore, it is difficult to finely adjust various properties. In addition, although positive photoresists formed by coating methods using solutions have good properties, it is impossible to convert them directly into electrodeposition paints for various reasons. Furthermore, positive photoresists made into electrodeposition paints also had problems with storage stability and film retention.

[0014]

[Problems to be Solved by the Invention] The present invention solves the above-mentioned problems of the prior art, is suitable for electrodeposition coating, has good residual film rate and storage stability, and has excellent photosensitivity and mechanical properties. An object of the present invention is to provide a positive photosensitive anionic electrodeposition coating resin composition capable of forming a positive photoresist, an electrodeposition coating bath using the same, and an electrodeposition coating method.

[0015]

[Means for Solving the Problem] As a result of intensive study, the present inventors selected (meth)acrylic resin, which is currently used in the manufacturing method of printed wiring boards, as a carboxyl group-containing resin, and developed the (meth)acrylic resin. In order to make the resin an excellent electrodeposition coating, it is essential to copolymerize a polymerizable monomer with a homopolymer glass transition point of 0°C or lower, and the compatibility with the (meth)acrylic resin thus obtained is essential. By combining an unprecedentedly good photosensitizer with a photosensitizer that has excellent developer resistance in the unexposed areas, and at the same time suppressing the occurrence of precipitation, it is possible to form a photoresist with the desired electrodeposition coating. We have now discovered a positive-working photosensitive anionic electrodeposition coating resin composition that has excellent photosensitive properties and mechanical properties of resist films, as well as excellent film retention and storage stability.

That is, the present invention provides (a) acrylic acid and/or
Or the glass transition point of methacrylic acid and homopolymer is 0℃
A resin obtained by neutralizing a (meth)acrylic resin with an acid value of 30 to 250 with a base, copolymerized with the following polymerizable monomer as an essential component, b) General formula (I)

[In the formula, R1 represents an alkyl group, R2 represents hydrogen, an alkyl group, an alkoxy group, or a nitro group, and R3 represents

[Chemical formula 6], m is an integer of 0 to 2, n is an integer of 1 to 3, and is selected so that the sum of m and n is an integer of 1 to 3] Compound and (c) general formula (II)

[In the formula, R4 represents an alkyl group, R5 represents hydrogen, an alkyl group, an alkoxy group, or a nitro group, and R6 represents

[Chemical formula 8], s is an integer of 0 to 2, t is an integer of 1 to 3, and is selected so that the sum of s and t is an integer of 1 to 3] The present invention relates to a positive photosensitive anionic electrodeposition coating resin composition containing the compound and an electrodeposition coating bath using the same.

The present invention also relates to an electrodeposition coating method characterized in that a substrate whose surface is covered with metal is immersed in the electrodeposition coating bath, and a DC voltage is applied using the substrate as an anode.

The present invention will be explained in detail below. The (meth)acrylic resin that is component (a) first contains acrylic acid or methacrylic acid as an essential component as a carboxyl group-containing polymerizable monomer. These are used so that the obtained (meth)acrylic resin has an acid value in the range of 30 to 250. If the acid value is less than 30, the water dispersibility and water dispersion stability will be affected when a base is added to the positive-type photosensitive anionic electrodeposition coating resin composition of the present invention and then water is added and dispersed. is poor and the composition settles. Furthermore, if the acid value exceeds 250, the appearance of the coating after electrodeposition will be poor. Acrylic acid or methacrylic acid may be used alone or in combination.

As another essential component of the (meth)acrylic resin which is component (a), a polymerizable monomer having a homopolymer glass transition point of 0° C. or lower is used. A polymerizable monomer whose homopolymer glass transition point is 0°C or lower means that the glass transition point of a polymer obtained by homopolymerizing the monomer is 0°C or lower. The glass transition point is measured by a conventional thermal analysis method, preferably by differential scanning calorimetry (DSC). Polymerizable monomers whose homopolymer glass transition point is 0°C or lower include ethyl acrylate, isopropyl acrylate, n-propyl acrylate, isobutyl acrylate, n-hexyl methacrylate, n-octyl methacrylate, n-decyl methacrylate, etc. There is,
Among them, n-butyl acrylate and 2-ethylhexyl acrylate are preferred. These polymerizable monomers may be used alone or in combination of two or more, and the amount used is 5 to 75 parts by weight based on 100 parts by weight of the total amount of copolymerizable monomers forming the polymer (a). The amount is preferably 20 to 60 parts by weight, and more preferably 20 to 60 parts by weight. If the amount used is less than 5 parts by weight, the glass transition point of the polymer will be high, and there is a risk that a film will not be formed when the electrodeposition paint is applied in combination with the photosensitive agent (components (b) and (c)). There is. On the other hand, if the amount used exceeds 75 parts by weight, the glass transition point of the polymer will be too low and the coating film after electrodeposition will tend to be sticky.

In addition to the above-mentioned polymerizable monomers, the (meth)acrylic resin as component (a) may contain, for example, methyl acrylate, methyl methacrylate, ethyl methacrylate,
Butyl methacrylate, cyclohexyl methacrylate, tetrahydrofurfuryl methacrylate, 2,2,2-
One or more common polymerizable monomers such as trifluoroethyl methacrylate, diacetone acrylamide, acrylonitrile, styrene, and vinyltoluene can be used in combination for copolymerization. The amount used can be 91 parts by weight or less based on 100 parts by weight of the total amount of copolymerizable monomers forming the resin as component (a).

The (meth)acrylic resin, which is component (a), can be obtained by generally preparing the above-mentioned polymerizable monomer in an organic solvent using a polymerization initiator such as azobisisobutyronitrile, azobisdimethylvaleronitrile, or benzoyl peroxide. It can be obtained by standard solution polymerization. The organic solvent used in this case is
Considering the use in electrodeposition paints, it is preferable to mainly use hydrophilic organic solvents such as dioxane, methoxyethanol, methoxypropanol, ethoxyethanol, propoxypropanol, and diethylene glycol. When a hydrophobic organic solvent such as toluene, xylene, or benzene is mainly used, it is necessary to distill off the solvent after resin synthesis and replace it with the hydrophilic organic solvent described above. The average molecular weight of the resin (in terms of standard polystyrene) is 5000 to 1500.
00 is preferred. If it is less than 5,000, the mechanical strength of the resist is weak, and if it exceeds 150,000, the electrodeposition coating properties tend to be poor and the appearance of the coating film tends to be poor.

The amount of (meth)acrylic resin used as component (a) is 100% of the total amount of components (a), (b) and (c).
It is preferably 30 to 95 parts by weight, more preferably 50 to 90 parts by weight. If the amount used is less than 30 parts by weight, the water dispersibility and water dispersion stability in the electrodeposition bath will be poor, and if it exceeds 95 parts by weight, the proportion of the photosensitizer (components (b) and (c)) will decrease. , sensitivity to light decreases.

Next, the compound represented by the general formula (I), which is the component (b), will be explained.

[Chemical formula 9]

R1 in the general formula (I) is an alkyl group, preferably an alkyl group having 1 to 18 carbon atoms, particularly an alkyl group having 1 to 12 carbon atoms, such as a methyl group or n-propyl group. , isopropyl group, n-octyl group, 2-ethylhexyl group, n-dodecyl group, etc. are preferable.

Further, R2 is hydrogen, an alkyl group such as methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, t-butyl group, n-hexyl group, methoxy group, ethoxy group, etc. group, propoxy group,
Any one is selected from an alkoxy group such as a butoxy group and a nitro group.

[0026] Furthermore, R3 is

Any of the following. In the general formula (I), m is an integer of 0 to 2, n is an integer of 1 to 3, and is selected such that the sum of m and n becomes an integer of 1 to 3.

The method for synthesizing the compound of general formula (I) is not particularly limited, but preferably trihydroxybenzoic acid ester (eg, gallic acid ester), dihydroxybenzoic acid ester, hydroxybenzoic acid ester (eg,
1,2-benzoquinonediazide-4-sulfonic acid chloride, 1,2-naphthoquinonediazide-4-sulfonic acid chloride or 1,
It can be obtained by subjecting 2-naphthoquinonediazide-5-sulfonic acid chloride to a condensation reaction. To give a specific example, a benzoic acid ester derivative having a hydroxyl group on the benzene ring, 1,2-benzoquinonediazide-4-sulfonic acid chloride, 1,2-naphthoquinonediazide-4-
An organic solvent is added to a mixture of sulfonic acid chloride or 1,2-naphthoquinonediazide-5-sulfonic acid chloride to dissolve it, and a base such as triethylamine, pyridine, or sodium carbonate (generally an aqueous solution) is added dropwise to this while stirring. After addition, the mixture is further stirred for 10 minutes to 8 hours to react. During this time, the temperature is preferably kept in the range of room temperature to 80°C, particularly 30 to 50°C.

In this way, benzoquinonediazide sulfonic acid chloride or naphthoquinonediazide sulfonic acid chloride may be entirely condensed to the hydroxyl group, or a portion of the hydroxyl group may be left and the rest may be condensed. Furthermore, as can be seen from the above synthesis example, there is a possibility that a mixture of compounds having different amounts of unreacted hydroxyl groups in one molecule may be obtained, but it is not necessary to isolate them. In any case, a compound of general formula (I), selected such that m is an integer of 0 to 2, n is an integer of 1 to 3, and the sum of m and n is an integer of 1 to 3. If so, both single products and mixtures are included within the scope of the present invention.

The amount of the compound represented by general formula (I) as component (b) is 5 to 70 parts by weight based on 100 parts by weight of the total amount of components (a), (b) and (c). The amount is preferably 10 to 50 parts by weight, and more preferably 10 to 50 parts by weight. If the amount used is less than 5 parts by weight, the sensitivity to light will decrease, and if it exceeds 70 parts by weight, water dispersibility and water dispersion stability in an electrodeposition bath will deteriorate.

Finally, the compound represented by the general formula (II), which is the component (c), will be explained.

[Chemical formula 11]

R4 in the general formula (II) is an alkyl group, preferably an alkyl group having 1 to 6 carbon atoms, particularly an alkyl group having 1 to 3 carbon atoms, such as a methyl group, an ethyl group, or a n-propyl group. and isopropyl group are preferred.

R5 is hydrogen, an alkyl group such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-octyl group, a 2-ethylhexyl group, or an n-dodecyl group, a methoxy group, an ethoxy group, or a propoxy group. or an alkoxy group such as a butoxy group, or a nitro group.

[0033] Also, R6 is

[Image Omitted] and s is an integer from 0 to 2, and t is from 1 to
The sum of s and t is an integer of 1 to 3.

The method of synthesizing the compound of general formula (II) is not particularly limited, but preferably 2'-alkyl-2,3,4-
Trihydroxybenzophenone, 3'-alkyl-2,
1,2-benzoquinonediazide-4-sulfonic acid chloride or 1,2-benzoquinone diazide-4-sulfonic acid chloride or 1,2-benzoquinonediazide-4-sulfonic acid chloride is added to derivatives having a hydroxy group and an alkyl group in the benzophenone skeleton such as 3,4-trihydroxybenzophenone and 2'-alkyl-2,3-dihydroxybenzophenone. -Naphthoquinone diazide-5
It can be obtained by condensation reaction of -sulfonic acid chloride or 1,2-naphthoquinonediazide-4-sulfonic acid chloride. To give a specific example, a derivative having a hydroxy group and an alkyl group in the benzophenone skeleton and 1,2-benzoquinonediazide-4-sulfonic acid chloride, 1,2-naphthoquinonediazide-4-sulfonic acid chloride, or 1,2- Adding an organic solvent to a mixture of naphthoquinonediazide-5-sulfonic acid chloride and dissolving it,
A base such as triethylamine, pyridine, or sodium carbonate (generally an aqueous solution) is added dropwise to this while stirring.
After the addition, the mixture is stirred for an additional 10 minutes to 8 hours to react. During this time, the temperature should be between room temperature and 80℃, especially between 30 and 50℃.
It is preferable to keep it within this range.

In this manner, benzoquinonediazide sulfonic acid chloride or naphthoquinonediazide sulfonic acid chloride may be entirely condensed to the hydroxyl group, or a portion of the hydroxyl group may be left and the rest may be condensed. Furthermore, as can be seen from the above synthesis example, 1
Although it is possible to obtain a mixture of compounds with different amounts of unreacted hydroxyl groups in the molecule, it is not necessary to isolate them. In any case, in the compound of general formula (II), s is an integer of 0 to 2, t is an integer of 1 to 3,
As long as the compound is selected such that the sum of s and t is an integer of 1 to 3, both a single product and a mixture are included within the scope of the present invention.

The amount of the compound of general formula (II) used as component (c) is the total amount of components (a), (b) and (c) 10
It is preferably 1 to 25 parts by weight, more preferably 2 to 10 parts by weight, relative to 0 parts by weight. If the amount used is less than 1 part by weight, the residual film ratio will not improve, and if it exceeds 25 parts by weight, the sensitivity will decrease or the water dispersibility and stability in the electrodeposition bath will deteriorate.

Furthermore, a sensitizer can also be added to the positive photosensitive anionic electrodeposition coating resin composition of the present invention. Examples of the sensitizer include pyrrole, imidazole, triazole, indole, benzimidazole, oxazolidone, piperidone, hydantoin, glycine,
Nitrogen-containing compounds having active hydrogen such as barbituric acid and derivatives thereof can be mentioned. The amount of these sensitizers used is preferably 30 parts by weight or less per 100 parts by weight of the total amount of components (a), (b) and (c). If it exceeds 30 parts by weight, the solubility of the resist increases during development and the residual film rate tends to decrease.

The positive photosensitive anionic electrodeposition coating resin composition of the present invention may further contain dyes, pigments, plasticizers, adhesion promoters, inorganic fillers, etc. as appropriate.

In order to convert the positive photosensitive anionic electrodeposition paint resin composition of the present invention containing the above-mentioned components (a), (b) and (c) as main components into an electrodeposition paint, first, (a
), (b) and (c) components, as well as the above-mentioned various components used as necessary, are preferably uniformly dissolved in a hydrophilic organic solvent, but this is not necessarily the case. The hydrophilic organic solvent referred to here includes, for example, dioxane, methoxyethanol, methoxypropanol, ethoxyethanol, propoxypropanol, diethylene glycol, and the like. These solvents can be used alone or in combination.
A mixture of two or more types may be used, and the amount used is preferably 300 parts by weight or less based on 100 parts by weight of the total solid content.

Next, a base is added to this solution to neutralize the carboxyl groups contained in the (meth)acrylic resin, which is component (a), thereby making it easier to water-solubilize or water-disperse the composition. . The base used here is not particularly limited, but examples include triethylamine, monoethanolamine, diethanolamine, diisopropylamine, dimethylaminoethanol, morpholine, ammonia, and sodium hydroxide, which may be used alone or in combination of two or more. It can be used as The amount of these bases used is preferably 0.3 to 1.0 equivalents per equivalent of carboxyl group in the (meth)acrylic resin as component (a). If the amount is less than 0.3 equivalents, the water dispersion stability in the electrodeposition coating bath will decrease, and if it exceeds 1.0 equivalents, the thickness of the coating film (photosensitive layer) after electrodeposition coating will become thinner, and the storage stability will also tend to decrease. This is not desirable.

Next, water is added to dissolve or disperse the positive photosensitive anionic electrodeposition coating resin composition in water to prepare an electrodeposition coating bath. The solid content of the electrodeposition coating bath is usually 5 to 20
The weight percent and pH are preferably in the range of 7.0 to 9.0. If the pH is less than 7.0, dispersion may deteriorate and electrophoresis may become difficult; if the pH exceeds 9.0, the electrodeposited film may be redissolved, resulting in no film being formed. In order to adjust the pH to the above-mentioned preferred range, the above-mentioned base may be added later to adjust the pH.

[0042] Furthermore, in order to improve the water dispersibility and dispersion stability of the positive photosensitive anionic electrodeposition coating resin composition, nonionic, cationic, anionic, etc. surfactants may be added as appropriate. can. Furthermore, a hydrophobic solvent such as toluene, xylene, or 2-ethylhexyl alcohol can be added as appropriate to increase the amount of coating during electrodeposition coating.

The electrodeposition coating bath thus obtained is used to coat the substrate surface (in this case, the substrate surface is iron, aluminum,
For electrocoating (coated with metals such as copper, zinc, and other metals and alloys), the substrate is immersed in an electrocoat bath as an anode, and a DC voltage of usually 50 to 400 V is applied for 10 The application is performed for seconds to 5 minutes. At this time, it is desirable to control the temperature of the electrodeposition coating bath at 15 to 30°C.

After the electrodeposition coating, the object to be coated is taken out of the electrodeposition coating bath, washed with water, drained, and then dried with hot air or the like. At this time, if the drying temperature is high, there is a risk that the quinone diazide group in the positive photosensitive anionic electrodeposition coating resin composition will decompose, so it is usually preferable to dry at 110° C. or lower.

The thickness of the coating film (photosensitive layer) thus obtained is preferably 2 to 50 μm. If the film thickness is less than 2 μm, developer resistance is low, and when used for manufacturing printed circuit boards, for example, when a resist pattern is formed and then etched, the etchant resistance and etch factor tend to be poor. Furthermore, if the film thickness exceeds 50 μm, the resolution of the resist pattern may decrease.

Next, the coating film is imagewise irradiated with actinic rays to photodecompose the exposed areas, and then the exposed areas are removed by development to obtain a resist pattern. As the active light source, one that emits light having a wavelength of 300 to 450 nm, such as a mercury vapor arc, a carbon arc, or a xenon arc, is preferably used.

Development is usually carried out by spraying alkaline water such as sodium hydroxide, sodium carbonate or potassium hydroxide, or by immersing the film in alkaline water.

[0048]

[Examples] The present invention will now be explained in more detail with reference to Examples and Comparative Examples. First, a method for synthesizing components (a), (b) and (c) used in Examples will be described.

Synthesis of (meth)acrylic resin as component (a) (a-1) Add 900 g of methoxypropanol to a flask equipped with a stirrer, reflux condenser, thermometer, dropping funnel, and nitrogen gas introduction tube, and stir. While blowing nitrogen gas, the temperature was raised to 90°C. When the temperature became constant at 90℃, 141g of acrylic acid, 3g of methyl methacrylate
2. A mixture of 00 g, 2-ethylhexyl acrylate, 559 g, and azobisisobutyronitrile 10 g.
Dropped into the flask over 5 hours, then heated at 90°C for 3 hours.
The mixture was kept warm while stirring. After 3 hours, a solution of 3 g of azobisisobutyronitrile dissolved in 100 g of methoxypropanol was added dropwise into the flask over 10 minutes, and then kept at 90° C. for 4 hours with stirring. The weight average molecular weight of the resin as component (a) thus obtained was 4.
2000, and the acid value was 108. Further, the solid content of the resin solution was 50.2% by weight.

(a-2) Add 1130 g of methoxypropanol to a flask equipped with the same equipment as in (a-1),
While stirring, nitrogen gas was blown into the mixture and the mixture was heated to a temperature of 90°C. When the temperature was constant at 90°C, a mixture of 108 g of methacrylic acid, 330 g of methyl methacrylate, 462 g of n-butyl acrylate, 100 g of 2-hydroxyethyl acrylate, and 10 g of azobisisobutyronitrile was added over 2.5 hours. The mixture was added dropwise into the flask, and then kept at 90° C. with stirring for 3 hours. After 3 hours, a solution of 3 g of azobisisobutyronitrile dissolved in 100 g of methoxypropanol was added dropwise into the flask over 10 minutes, and then kept at 90° C. for 4 hours with stirring. The weight average molecular weight of the resin as component (a) thus obtained was 56,000, and the acid value was 71.7. Further, the solid content of the resin solution was 44.6% by weight.

Synthesis of photosensitive agent (b) (b-1) 21.2 g (0.1 mol) of n-propyl gallate and 1,
2-naphthoquinonediazide-5-sulfonic acid chloride 5
A solution of 3.7 g (0.2 mol) dissolved in 500 ml of dioxane was heated to 40° C. with stirring, and 21 g of triethylamine was added dropwise to this solution over 30 minutes. After the dropwise addition, the reaction was further carried out at 40°C for 3 hours, and then the reaction product was poured into a 0.1N aqueous hydrochloric acid solution, and the resulting precipitate was purified and filtered to form n-propyl gallate and 1,2-naphtho. Ester compound with quinonediazide-5-sulfonic acid 55
I got g.

(b-2) 28.2 g (0.1 mol) of 2-ethylhexyl gallate and 80.4 g (0.3 mol) of 1,2-naphthoquinonediazide-5-sulfonic acid chloride were dissolved in 800 ml of dioxane. The resulting solution was heated to 40° C. with stirring, and 32 g of triethylamine was added dropwise thereto over 30 minutes. After the dropwise addition, the reaction was further carried out at 40°C for 3 hours, and then the reaction product was poured into a 0.1N aqueous hydrochloric acid solution, and the resulting precipitate was purified and filtered to form 2-ethylhexyl gallate and 1,2-naphtho. 91 g of an ester compound with quinonediazide-5-sulfonic acid was obtained.

Synthesis of (c) component photosensitizer (c-1) 2'
-A solution of 23.2 g (0.1 mol) of methyl-2,3,4-trihydroxybenzophenone and 53.7 g (0.2 mol) of 1,2-naphthoquinonediazide-5-sulfonic acid chloride in 500 ml of dioxane. was heated to 40° C. with stirring, and 21 g of triethylamine was added dropwise thereto over 30 minutes. After the dropwise addition, the reaction was further carried out at 40°C for 3 hours, and then the reaction product was poured into a 0.1N aqueous hydrochloric acid solution, and the resulting precipitate was purified and filtered to give 2'-methyl-2,
60 g of an ester compound of 3,4-trihydroxybenzophenone and 1,2-naphthoquinonediazide-5-sulfonic acid was obtained.

(c-2) 2'-methyl-2,3,4-trihydroxybenzophenone 23.2 g (0.1 mol)
and 80.4 g (0.3 mol) of 1,2-naphthoquinonediazide-5-sulfonic acid chloride in 700 m of dioxane.
1 of the solution was heated to 40° C. with stirring, and 21 g of triethylamine was added dropwise thereto over 30 minutes. After the dropwise addition, the reaction was further carried out at 40°C for 3 hours, and then the reaction product was reduced to 0.
．． Injected into 1N aqueous hydrochloric acid solution and purified the resulting precipitate.
The mixture was filtered to obtain 85 g of an ester compound of 2'-methyl-2,3,4-trihydroxybenzophenone and 1,2-naphthoquinonediazide-5-sulfonic acid.

Example 1 20 parts by weight of the photosensitizer (b-1), 5 parts by weight of the photosensitizer (c-1), and 100 parts by weight of the resin solid content of (a-1) were added.
-1) 0.75 per equivalent of carboxyl group of resin
Dissolve an equivalent amount of triethylamine and then disperse in water by slowly adding water dropwise to obtain a solution with a solid content of 10% and a pH of 7.5.
An electrodeposition bath was obtained.

[0056] In this electrodeposition coating bath, a stainless steel plate (SUS304, 200 mm x 7
5 mm x 1 mm) was immersed as a cathode, and a DC voltage of 180 V was applied for 3 minutes at a temperature of 25° C. to form an electrodeposition coating film (photoresist film) on the surface of the copper clad laminate. Thereafter, it was washed with water, drained, and dried at 80° C. for 15 minutes to obtain a film thickness of 8 μm. Next, this coating film was exposed to light using a 3 kW ultra-high pressure mercury lamp through a photomask, and then developed with a 1% aqueous sodium carbonate solution. At this time, in order to evaluate the photosensitivity, a step tablet (a photomask with an optical density of 0.05 as the first step and an optical density increasing by 0.15 for each step is used).The exposure amount to obtain 3 steps. 250m when measured.
J/cm2, and the obtained resist pattern had a high resolution of 40 μm. On the other hand, the remaining film rate in the unexposed portion was 100%. Further, in this electrodeposition coating bath, no precipitation occurred even after one month and three months after bath preparation.

Examples 2 to 5 Resist patterns were prepared in the same manner as in Example 1 using the compositions and conditions shown in Table 1, and the exposure amount, resolution, residual film rate, and presence or absence of precipitation (storage stability) was evaluated. The results are shown in Table 1. In all cases, it was confirmed that they had high sensitivity and resolution, and were excellent in film residual rate and storage stability.

Comparative Example 1 An electrodeposition coating bath was prepared by adding only the photosensitive agent (b-1) to the resin (a-1), a resist pattern was prepared in the same manner as in Example 1, and the characteristics were evaluated. The results are shown in Table 1. As is clear from Table 1, there were no problems with sensitivity and resolution, but
The residual film rate was not very high at 80%, and precipitation occurred 3 weeks after the bath was built.

In Table 1, the presence or absence of precipitation is indicated by the following symbols. ○...Precipitation has occurred. ×...Precipitation has occurred.

[0060]

[Table 1]

[0061]

[Effects of the Invention] The positive photosensitive anionic electrodeposition paint resin composition of the present invention provides an electrodeposition paint that can fully exhibit the advantages of forming a photoresist by electrodeposition coating.
We can provide a positive photoresist that is unprecedentedly suitable for electrodeposition coating, has good storage stability, has excellent photosensitivity and mechanical properties of the resist film, and has a high sensitivity and high resolution resist with a high residual film rate. A pattern can be formed. Furthermore, by using the positive photosensitive anionic electrodeposition paint resin composition of the present invention, it is possible to use the resist as a relief or to form a photoresist for etching or plating using a copper-clad laminate as a base. can.

Claims (6)

[Claims] Claim 1: (a) An acid value 30 obtained by copolymerizing acrylic acid and/or methacrylic acid and a polymerizable monomer whose homopolymer glass transition point is 0° C. or lower as essential components.
-250 (meth)acrylic resin neutralized with a base, (b) General formula (I) [Formula, R1 represents an alkyl group, R2 represents hydrogen, an alkyl group, an alkoxy group or a nitro group] R3 represents one of the following formulas, m is an integer of 0 to 2, n is an integer of 1 to 3, and the sum of m and n is an integer of 1 to 3. ] and (c) general formula (II) [Formula, R4 represents an alkyl group, R5 represents hydrogen, an alkyl group, an alkoxy group, or a nitro group, and R6 represents a 4], s is an integer of 0 to 2, t is an integer of 1 to 3, and is selected such that the sum of s and t is an integer of 1 to 3]. A positive photosensitive anionic electrodeposition coating resin composition comprising: Claim 2: Claim 1 wherein the polymerizable monomer whose homopolymer has a glass transition point of 0°C or less is n-butyl acrylate and/or 2-ethylhexyl acrylate.
The positive photosensitive anionic electrodeposition coating resin composition described above. Claim 3: R in the compound represented by general formula (I)
The positive-working photosensitive anionic electrodeposition coating resin composition according to claim 1 or 2, wherein 1 is an alkyl group having 1 to 18 carbon atoms. 4. Claims 1 and 2, wherein R4 in the compound represented by general formula (II) is an alkyl group having 1 to 5 carbon atoms.
or the positive photosensitive anionic electrodeposition coating resin composition according to 3. 5. An electrodeposition coating bath comprising the positive photosensitive anionic electrodeposition coating resin composition according to claim 1, 2, 3 or 4. 6. An electrodeposition coating method, characterized in that a substrate whose surface is covered with metal is immersed in the electrodeposition coating bath according to claim 5, and a DC voltage is applied using the substrate as an anode.