JPH06322597A - Electrodeposition coating method - Google Patents

Abstract

PURPOSE:To improve the uniformity in thickness of an electrodeposited film (photoresist) in the method for forming a photoresist by electrodeposition coating. CONSTITUTION:A conductive substrate 3 is dipped in an electro-deposition bath for a photoresist to form a photoresist film on the substrate surface by electrodeposition coating. In this case, the bath soln. is allowed to flow at a speed of 0.05-2m/sec close to the substrate 3 surface and in parallel to the substrate during electrodeposition coating. A uniform photoresist film is formed in this way over the whole surface of the substrate 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrodeposition coating method for forming a photoresist film having a uniform film thickness on the surface of a conductive substrate.

[0002]

2. Description of the Related Art When manufacturing a printed circuit board,
First, a photoresist film is formed on a conductive substrate such as a copper clad laminate, and then an actinic ray is imagewise irradiated and developed to form a resist pattern. As the method for forming the photoresist film, the electrodeposition coating method has good followability to irregularities on the substrate surface, is less likely to leave unpainted parts, pinholes, etc., and can form a photoresist film with good adhesion in a short time. It has been widely adopted because of its many advantages.

By the way, in the electrodeposition coating method, an electrodeposition coating film formed on the surface of a conductive substrate, which is an object to be dipped in an electrodeposition bath, is generally deeply dipped and thinly dipped. It is known to be thinner than the film thickness of.

Therefore, as shown in FIG. 5, the bath liquid in the electrodeposition bath 1 is overflowed to the adjacent overflow bath 2 and returned to the vicinity of the bottom of the electrodeposition bath 1 through the pipe 5 by the circulation pump 6. Circulate the bath liquid with
As a result, the method of homogenizing the electrodeposition bath and reducing the variation of the film thickness depending on the depth of the immersion described above have been taken. However, in such a conventional method, for example, the distance between the deeply immersed portion and the shallowly immersed portion is 20.
In the case of cm, when forming an average film thickness of 15 μm, the film thickness difference can be reduced to about 3 μm at most, and this film thickness difference is not so great when the object to be coated is an automobile body, home electric appliances or the like. Although not a problem, it was an unsatisfactory method when applied to an object to be coated such as a printed circuit board that requires high accuracy.

[0005]

DISCLOSURE OF THE INVENTION The present invention overcomes the above-mentioned drawbacks of the conventional electrodeposition coating method and can form an electrodeposition coating film having a uniform film thickness, that is, a photoresist film, on the entire surface. Provide a painting method.

[0006]

The present invention is an electrodeposition coating method in which a conductive substrate is immersed in an electrodeposition bath for photoresist to form a photoresist film on the surface of the substrate. A method for electrodeposition coating, characterized in that the electrodeposition coating is performed while flowing a bath liquid near the surface of the substrate and in a direction parallel to the substrate at a flow rate of about 0.05 to 2 m / sec. Is.

The present invention will be described in detail below. As the electrodeposition bath for photoresist used in the present invention, any conventionally known electrodeposition bath for photoresist can be applied without particular limitation. That is, the known electrodeposition bath for photoresist is
There are anion type and cation type classified according to the electrodeposition coating method, and there are negative type and positive type according to the photosensitive system. In the present invention, anion type / negative type,
The electrodeposition baths used in the combination of cationic / negative type, anionic / positive type and cationic / positive type can be applied.

The anion type is a system in which the resin dissociates into anions in the electrodeposition bath and the resin anions are electrophoresed and deposited on the conductive substrate which is the anode, and the cation type is in the electrodeposition bath. In this method, the resin is dissociated into cations, and the resin cations are electrophoresed and deposited on the conductive substrate that is the cathode.
The negative type is a system in which the exposed part is photocured and becomes insoluble in a developing solution, and the unexposed part is dissolved and developed, and the positive type is
This is a method of dissolving and developing the exposed area.

In the following, the electrodeposition bath for photoresist according to the present invention will be illustrated and described according to the above categories.

Electrodeposition bath in the case of anion type / negative type Acid value about 20 to 300, weight average molecular weight about 1,000 to 1
Neutralized product of 50,000 carboxyl group-containing resin with basic organic compound, ethylenically unsaturated compound having photopolymerizable unsaturated bond, photopolymerization initiator and water, and further organic solvent and coloring as required. Agent, filler, plasticizer,
It is formed by adding various additives such as a thermal polymerization inhibitor and a surfactant.

As the carboxyl group-containing resin,
A typical example is a copolymer of a carboxyl group-containing polymerizable monomer such as (meth) acrylic acid or itaconic acid and a polymerizable monomer such as (meth) acrylic acid ester or styrene. The carboxyl group-containing resin may have a photopolymerizable unsaturated bond. Examples of such a resin include a high acid value carboxyl group-containing resin reacted with a glycidyl group-containing unsaturated compound, a carboxyl group-containing resin having a hydroxyl group reacted with a free isocyanate group-containing unsaturated compound, and an epoxy resin and A reaction product of a polybasic acid anhydride with an addition reaction product with a saturated carboxylic acid, or a hydroxyl group-containing polymerizable monomer with an addition reaction product of a conjugated diene polymer or a conjugated diene copolymer with an unsaturated dicarboxylic acid anhydride. Typical ones are those that have been made.

Examples of the basic organic compound as the neutralizing agent include monoethanolamine, diethanolamine, diisopropylamine, dimethylaminoethanol, diethylamine, triethylamine, butylamine and tri-n.
-Butylamine, tri-n-octylamine, triphenylamine, triethanolamine, dimethylethanolamine, propylamine, t-butylamine, pyridine, morpholine, piperidine, pyrrolidine monoethanolamine, etc. are representative. In addition, the amount of the neutralizing agent to be used is appropriately about 0.3 to 1.0 equivalent to 1 equivalent of the carboxyl group in the carboxyl group-containing resin.

As the ethylenically unsaturated compound having a photopolymerizable unsaturated bond, for example, an α, β-unsaturated carboxylic acid is added to a polyhydric alcohol excluding polyethylene glycol condensed with one or more ethylene glycols. As the obtained compound, trimethylolpropane di (meth) acrylate, trimethylolpropane tri (meth) acrylate, tetramethylolmethane tri (meth) acrylate, tetramethylolmethane tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dimethy! Pentaerythritol hexa (meth) acrylate and the like are included, and glycidyl group-containing compounds include α, β
Examples of the compound obtained by adding an unsaturated carboxylic acid include trimethylolpropane triglycidyl ether triacrylate, bisphenol A glycidyl ether di (meth) acrylate and the like, and polyvalent carboxylic acids (phthalic anhydride etc.) and hydroxyl group. And an ester compound with a substance having an ethylenically unsaturated group (β-hydroxyethyl (meth) acrylate, etc.), a urethane diacrylate compound having a urethane skeleton, and the like.

When the carboxyl group-containing resin has photopolymerizable unsaturated bonds, the ethylenically unsaturated compound having these photopolymerizable unsaturated bonds is not always necessary. Examples of the photopolymerization initiator include aromatic ketones such as benzophenone, N, N'-tetramethyl-4,4'-diaminobenzophenone, 4-methoxy-4'-dimethylaminobenzophenone, 2-ethylanthraquinone and phenanthrenequinone. Benzoin ethers such as benzoin methyl ether, benzoin ethyl ether, benzoin phenyl ether, methyl benzoin,
Benzoin such as ethylbenzoin, 2- (o-chlorophenyl) -4,5-diphenylimidazole dimer, 2
Typical examples include-(o-chlorophenyl) -4,5-di (m-methoxyphenyl) imidazole dimer and 2,4-di (p-methoxyphenyl) -5-phenylimidazole dimer. To be

The electrodeposition bath is a resin 100 containing a carboxyl group.
About 20 to 100 parts by weight of an ethylenically unsaturated compound having a photopolymerizable unsaturated bond and about 0.5 to 15 parts by weight of a photopolymerization initiator are appropriately blended with respect to parts by weight. It is suitable that the solid content of the bath is about 5 to 20% by weight and the pH is about 6 to 9.

Cationic / negative type electrodeposition bath Amine value of about 30 to 300, weight average molecular weight of about 1,000
.About.150,000 neutralized product of a primary to tertiary amino group-containing resin with an acidic compound, an ethylenically unsaturated compound having a photopolymerizable unsaturated bond, a photopolymerization initiator and water,
Further, it is formed by adding various additives such as an organic solvent, a colorant, a filler and a plasticizer, if necessary.

Examples of the amino group-containing resin include aminoethyl (meth) acrylate, N, N'-dimethylamino (meth) acrylate, N, N'-dimethylaminobutyl (meth) acrylate, and other amino group-containing polymerizable monomers. And (meth) acrylic acid ester, copolymers with polymerizable monomers such as styrene, glycidyl (meth) acrylate, glycidyl group-containing polymerizable monomers such as glycidyl (meth) acrylamide and (meth) acrylic acid ester,
A typical example is a resin obtained by adding an amine compound such as dimethylamine, diethanolamine, piperidine or morpholine to a copolymer with a polymerizable monomer such as styrene.

The amino group-containing resin may have a photopolymerizable unsaturated bond. Typical examples of the acidic compound as the neutralizing agent include acetic acid, propionic acid, lactic acid, formic acid, phosphoric acid and sulfuric acid.
The amount of the neutralizing agent to be used is appropriately about 0.3 to 1.0 equivalent with respect to 1 equivalent of amino group in the amino group-containing resin.
Examples of the ethylenically unsaturated compound having a photopolymerizable unsaturated bond and the photopolymerization initiator include the same ones as exemplified in the case of the anionic / negative type described above.

The electrodeposition bath contains about 20 to 100 parts by weight of an ethylenically unsaturated compound having a photopolymerizable unsaturated bond and 100 parts by weight of a photopolymerization initiator per 100 parts by weight of an amino group-containing resin.
It is suitable to add 5 to 15 parts by weight, and it is suitable that the solid content of the electrodeposition bath is about 5 to 20% by weight and the pH is about 3 to 9.

Anionic / Positive Electrodeposition Bath Acid Value: about 20 to 300, Weight Average Molecular Weight: about 1,000 to 1
50,000 of a quinonediazide group- and carboxyl group-containing resin neutralized product with a basic organic compound, or a carboxyl group-containing resin neutralization product of a basic organic compound with a compound having two or more quinonediazide groups in the molecule It is typically composed of a mixture and water and, if necessary, various additives such as an organic solvent, a colorant, a filler and a plasticizer.

Examples of the quinonediazide group- and carboxyl group-containing resin include carboxyl group-containing polymerizable monomers such as (meth) acrylic acid and itaconic acid, and 2-hydroxyethyl (meth) acrylate and t-butylaminoethyl (meth) acrylate. 1,2-naphthoquinone-2-
Copolymerization of addition reaction products obtained by reacting quinonediazides such as diazido-5-sulfonyl chloride and 1,2-benzoquinone-2-diazide-4-sulfonyl chloride with polymerizable monomers such as (meth) acrylic acid ester and styrene A typical example is coalescence. The content of quinonediazide groups in the resin is suitably 0.04 to 0.20 per 100 resin molecular weight. The carboxyl group-containing resin and the neutralizing agent may be the same as those exemplified in the case of the above-mentioned anionic / negative type.

Typical examples of the compound having two or more quinonediazide groups in the molecule include addition reaction products obtained by reacting the above-mentioned quinonediazides with gallic acid ester, trihydroxybenzophenone and the like.
In addition, a neutralized product of the carboxyl group-containing resin of the above mixture with a basic organic compound and a quinonediazide group are contained in the molecule in an amount of 2
The mixing ratio of the compounds having one or more is suitably 5 to 100 parts by weight with respect to 100 parts by weight of the former. Suitably, the solid content of the electrodeposition bath is about 5 to 20% by weight and the pH is about 6 to 9.

Cationic / Positive Electrodeposition Bath Amine value of about 30 to 300, weight average molecular weight of about 1,000
To 150,000 quinonediazide groups and primary to tertiary amino group-containing resins, which are neutralized with acidic compounds and the balance water, and if necessary, various additives such as organic solvents, colorants, filler plasticizers, etc. It is typical to consist of the addition of.

As the quinonediazide group- and amino group-containing resin, t-butylaminoethyl (meth) acrylate, t-butylstyrene, etc. are reacted with the quinonediazides exemplified in the case of the anionic / positive type as described above. 1 and the case of cationic / negative type
Representative examples thereof include a tertiary amino group-containing polymerizable monomer and, optionally, a copolymer with a polymerizable monomer such as (meth) acrylic acid ester and styrene. The content of quinonediazide groups in the resin is suitably 0.04 to 0.20 per 100 resin molecular weight. Examples of the neutralizing agent include the same ones as exemplified in the case of the above cationic / negative type. Suitably, the solid content of the electrodeposition bath is about 5 to 20% by weight and the pH is about 3 to 9.

Next, the electrodeposition coating method of the present invention will be described with reference to the drawings. The electrodeposition coating apparatus used in the present invention is basically a conventionally known one as shown in FIG. 5 except that the piping in the electrodeposition bath is changed to a piping system described later. A pipe system as shown in FIGS. 1 to 4 is provided near the surface of a conductive substrate such as a copper clad laminate soaked in a bath so that the bath liquid flows in a direction parallel to the substrate.
It is installed inside.

That is, in a system in which the bath liquid in the overflow bath 2 is overflowed into the overflow bath 2 and the bath liquid in the overflow bath 2 is returned to the electroplating bath 1 again by the circulation pump 6 through the pipe 5 The piping system shown in FIGS.

FIG. 1 shows a plurality of holes formed in two pipes a and b which are in parallel with each other so that the bath liquid in the overflow tank 2 is connected to the right end vertical portion via the pipe a portion. b) and b ′ again so as to flow out into the electrodeposition bath 1 so that the bath liquid flows from the right to the left of the conductive substrate 3 immersed between the pipes a and b in parallel to the surface of the substrate. It is a piping system.

FIG. 2 shows the inside of the overflow tank 2 through a plurality of holes b and b'opened in two pipes C and D in parallel with each other in the horizontal portion near the bottom of the electrodeposition bath 1. The bath liquid of No. 1 was again discharged into the electrodeposition bath 1 so that the bath liquid could flow from the lower side to the upper side of the conductive substrate 3 immersed between the pipes C and D in a direction parallel to the substrate surface. It is a piping system.

FIG. 3 shows a plurality of holes b formed in two pipes a and b which are in communication with each other and are in parallel with each other at the right end vertical portion.
It is in parallel with the piping system of FIG. 1 through which the bath liquid flows out from b ′ and the vertical portion at the left end, which is located farther from the conductive substrate (not shown) than the piping a and b. This is a piping system in which a plurality of holes c and c'opened respectively in two pipings E and F are provided. In this piping system, the bath liquid flowing out from the holes b and b'allows the bath liquid to flow from the right to the left of the conductive substrate 3 in parallel with the surface of the substrate, while the holes c,
The bath liquid flowing out from c'flows the bath liquid in the vicinity of the electrodeposition bath to homogenize the bath liquid in the entire bath.

FIG. 4 shows the overflow tank 2 through a plurality of holes b and b'opened in two pipes G and H which are in parallel with each other and communicate with a horizontal portion near the upper end of the electrodeposition bath 1. In the pipe system that causes the bath liquid to flow out again into the electrodeposition bath 1, in a horizontal portion near the bottom of the electrodeposition bath 1 that is farther from the conductive substrate (not shown) than the pipes and the electrodes. , A pipe system in which a plurality of holes c and c'opened respectively in two pipes communicating with each other and in a parallel state are provided. In this piping system, the bath liquid flowing out from the holes b and b'allows the bath liquid to flow in a downward direction from above the conductive substrate substantially parallel to the surface of the substrate, while flowing out from the holes c and c '. The bath liquid is made to flow around the electrodeposition bath to homogenize the bath liquid in the entire bath.

1 to 4 exemplify a typical piping system for flowing a bath liquid in a direction parallel to a conductive substrate as described above. A piping system other than these piping systems may be used as long as it is a piping system that allows the bath liquid to flow. In the method of the present invention, the flow rate of the bath liquid is about 0.05 to 2 m / sec, preferably 0.1 to 1 m / sec near the surface of the conductive substrate, preferably within 6 cm, in a direction parallel to the substrate. Electrodeposition coating while flowing

The flow velocity within the above range can be obtained by adjusting the circulation pump pressure, the diameter and number of holes formed in the pipe, and the like.
The flow velocity can be measured with a commercially available flow velocity meter or the like.
If the flow rate is slower than the above range, the effect of forming a uniform film thickness becomes low, while if it becomes too fast, bubbles are likely to be contained in the electrodeposition bath, and the immersed conductive substrate sways in the bath, Becomes unstable.

The reason why an electrodeposition coating film having a uniform film thickness can be obtained by the method of the present invention is not clear, but it is presumed that it is probably due to the following reasons. Normally, during electro-deposition coating, Joule heat is generated, which causes a slight temperature difference between the deeply-immersed portion and the shallow-dipped portion of the conductive substrate. When a conductive substrate that has been washed with water is dipped in a wet state, a large amount of pretreatment liquid or washing water is likely to remain below the vertically standing substrate (that is, where it is deeply dipped). It is considered that there is a difference in the substitution rate of the treatment solution or rinsing water and the bath solution on the substrate surface at the location and the location where the bath is shallowly dipped, etc. It is considered that the cause is eliminated by causing the fluid to flow near the surface and in the direction parallel to the substrate. If the bath liquid is made to flow in a turbulent state, an electrodeposition coating film having a non-uniform film thickness tends to occur irregularly regardless of the degree of immersion depth, which is not preferable.

Next, a method of manufacturing a resist pattern using the electrodeposition coating method of the present invention will be described. First, the conductive substrate is immersed in the above-mentioned electrodeposition bath placed in an electrodeposition bath and controlled at a temperature of about 15 to 30 ° C.
DC current of ~ 350mA / dm ² or 5 in case of constant voltage method
Apply a DC voltage of 0 to 500 V for 10 seconds to 5 minutes,
An electrodeposition coating film having a film thickness of about 5 to 50 μm, that is, a photoresist film is formed on a conductive substrate. When the electrodeposition bath is anionic, the conductive substrate is an anode, and when it is cationic, the conductive substrate is a cathode.

After electrodeposition coating, the substrate is pulled out from the electrodeposition bath, washed with water, drained and then dried with hot air or the like. At this time, if the drying temperature is high, the photoresist film may be deteriorated, so it is usually desirable to dry at a temperature of 120 ° C. or lower. After the photoresist film is formed on the substrate in this way, the surface is irradiated with an actinic ray in a predetermined image. If necessary (for example, when the photoresist is a chemical amplification system), it is further heated at 60 to 150 ° C. for 1 to 30 minutes. The light source of the actinic ray has a wavelength of about 300 to 45.
Those that emit 0 nm light rays, such as mercury vapor arc, carbon arc, and xenon arc are preferably used.
Then, a resist pattern is formed by development.

In the development, when the photoresist film is formed in an anionic electrodeposition bath, alkaline water such as sodium hydroxide, sodium carbonate, sodium metasilicate and potassium hydroxide is usually sprayed or immersed in the alkaline water. Done. On the other hand, when the photoresist film is formed in a cationic electrodeposition bath, it is usually carried out by spraying an acidic liquid such as acetic acid or lactic acid or an organic solvent such as ethanol, chlorothene or trichlene, or immersing it in them.

[0037]

EXAMPLES The present invention will now be described in more detail by way of examples. <Preparation of electrodeposition bath A> 213 g of propylene glycol monomethyl ether and 917 g of methyl cellosolve were added to a flask equipped with a stirrer, a reflux condenser, a thermometer, a dropping funnel and a nitrogen gas introducing tube, and the mixture was stirred, and while blowing nitrogen gas, 100 Warmed to ° C. When the temperature became constant at 100 ° C, a mixture of 185 g of methacrylic acid, 595 g of methyl methacrylate, 214 g of ethyl acrylate and 10 g of azobisisobutyronitrile was dropped into the flask over 3 hours, and then stirred at 100 ° C. While keeping it warm for 3.5 hours. After 3.5 hours, a solution obtained by dissolving 5 g of azobisdimethylvaleronitrile in a mixed solvent of 20 g of propylene glycol monomethyl ether and 80 g of methyl cellosolve was added dropwise into the flask over 10 minutes, and then, again at 90 ° C. for 4 hours with stirring. Kept warm. The resin as a precursor thus obtained had a weight average molecular weight of 35,000 and an acid value of 120. The solid content of the resin solution was 45.3% by weight.

Next, 650 g of this resin solution was mixed with 200 g of pentaerythritol tetraacrylate (manufactured by Sartomer Company, trade name SR-295) and 3 of benzophenone.
0 g, N, N'-tetraethyl-4,4'-diaminobenzophenone 1 g, propylene glycol monomethyl ether 20 g and methyl cellosolve 90 g were added and dissolved, and 35 g of triethylamine as a basic organic compound was added and dissolved in this solution. , The precursor resin in the solution was neutralized. Next, while stirring this solution, 4,700 g of ion-exchanged water was gradually added dropwise to obtain an electrodeposition bath A. The solid content of this electrodeposition bath A was 10% by weight, and the pH was 7.5 at 25 ° C.

<Preparation of electrodeposition bath B> Stirrer, reflux condenser,
226 g of propylene glycol monomethyl ether in a flask equipped with a thermometer, a dropping funnel and a nitrogen gas introducing tube.
And 226 g of methyl cellosolve were added and stirred, and the mixture was heated to 90 ° C. while blowing nitrogen gas. When the temperature became constant at 90 ° C., 43.2 g of methacrylic acid, 132 g of methyl methacrylate, and 185 n-butyl acrylate.
g, 2-hydroxyethyl acrylate 39.8 g and azobisisobutyronitrile 4 g were mixed to obtain 2.5
The mixture was dropped into the flask over a period of time and then kept at 90 ° C. for 3 hours while stirring. After 3 hours, a solution prepared by dissolving 1.2 g of azobisisobutyronitrile in a mixed solvent of 20 g of propylene glycol monomethyl ether and 20 g of methyl cellosolve was added dropwise into the flask over 10 minutes, and then, again at 90 ° C with stirring. It was kept warm for 4 hours.

The resin thus obtained had a weight average molecular weight of 56,000 and an acid value of 72. The solid content of the resin solution was 44.6% by weight. On the other hand, a solution prepared by dissolving 21.2 g of n-propyl gallate and 53.7 g of 1,2-naphthoquinone-2-diazide-5-sulfonyl chloride in 500 ml of dioxane while stirring was 40%.
After heating to 0 ° C., 21 g of triethylamine was added dropwise to this over 30 minutes, and after reacting at the same temperature for 3 hours, it was poured into a 0.1N aqueous hydrochloric acid solution, and the obtained precipitate was purified and filtered. Thus, 55 g of an ester compound of sensitizer-n-propyl gallate and 1,2-naphthoquinonediazide-5-sulfonic acid was obtained. 170 g of the resin solution, 20 g of the photosensitizer and 5.8 g of triethylamine were mixed and dissolved, and 760 g of ion-exchanged water was gradually added dropwise to this solution to obtain an electrodeposition bath B. The solid content of this electrodeposition bath B was 10% by weight, and the pH was 7.9 at 25 ° C.

Example 1 In an apparatus comprising an electrodeposition bath 1 and an overflow bath 2 of the sizes shown in FIGS. 6 and 7 (using a stainless steel plate 4 as an electrode), the piping system shown in FIG. The distance between the pipe c and the pipe d is 30 mm, the pipe inner diameter is 13 mm, and the hole diameter is 1.8 mm
Was installed. The electrodeposition bath A was put in the electrodeposition bath, and while it was overflowed into the overflow bath, the circulation pump was used to return the electrodeposition bath to the electrodeposition bath again, and electrodeposition coating was performed under the following conditions.

Glass epoxy copper clad laminate (MCL-E-61 manufactured by Hitachi Chemical Co., Ltd.) [width × length × thickness = 250 × 20]
0 × 1.6 mm] as the position shown in FIG. 2 and immersed in the central portion between the pipe C and the pipe D, and a DC voltage of 120 V was applied for 3 minutes,
An electrodeposition coating film (photoresist film) was formed on the above laminate. In addition, at the time of electrodeposition coating, the lower end portion of the laminated plate (pipe C,
D side) The flow velocities of the bath liquid on the surface parallel to the laminate and the flow velocities of the bath liquid on the upper end surface parallel to the laminate are 0.2 m / sec and 0.1 m / sec, respectively. Met. However, the flow velocity was measured in a state in which a flow velocity meter (digital velocity meter UC-3 manufactured by Tamaya Measurement System Co., Ltd.) was in contact with the surface of the laminated plate (hereinafter, measured in the same manner). After that, it was washed with water, drained and dried at 80 ° C. for 15 minutes. This was exposed to a light amount of 60 mJ / cm ² with a 3 kW ultra-high pressure mercury lamp.

With respect to the cured photoresist film, the film thickness at a position 1 cm above the lower end and 1 cm below the upper end of the laminate was measured at 1 cm intervals. The average film thickness of the measured film thickness and the film thickness difference between the maximum film thickness and the minimum film thickness were as shown in Table 1.

Example 2 In Example 1, instead of the piping system shown in FIG. 2, the piping system shown in FIG. 3 (the distance between the piping a and the piping b is 30 mm, the distance between the piping e and the piping is 200 mm, the piping inner diameter is 13 mm, the hole diameter is 1.8 mm) is installed, the laminated plate is immersed in the central portion between the pipe a and the pipe b, and at the time of electrodeposition coating, the bath liquid of the surface of the right end portion of the laminated plate (the pipe a and the b side), A photoresist film is formed in the same manner except that the flow velocity in the direction parallel to the laminate and the flow velocity of the bath liquid on the left end surface parallel to the laminate are 1.0 m / sec and 0.5 m / sec, respectively. did. When each film thickness was measured in the same manner as in Example 1, the average film thickness and the difference between the maximum film thickness and the minimum film thickness were as shown in Table 1.

Comparative Example 1 A photoresist film was formed in the same manner as in Example 1 except that the electrodeposition bath was not circulated during electrodeposition coating and the flow rate of the bath liquid was set to 0. When each film thickness was measured in the same manner as in Example 1, the average film thickness and the difference between the maximum film thickness and the minimum film thickness are shown in Table 1.
It was as shown in.

COMPARATIVE EXAMPLE 2 In Example 1, instead of the conventional piping system shown in FIG.
A photoresist film was formed in the same manner except that a piping system having holes shown in (1) was provided only in the downward direction and turbulent flow was generated during electrodeposition coating. During electrodeposition coating, the flow velocity of the bath liquid on the lower end surface of the laminated plate in the direction parallel to the laminate plate and the flow velocity of the bath liquid on the top surface of the laminated plate in the direction parallel to the laminate plate are:
The values were 0.03 m / sec and 0.02 m / sec, respectively. When each film thickness was measured in the same manner as in Example 1, the average film thickness and the difference between the maximum film thickness and the minimum film thickness were as shown in Table 1.

Embodiment 3 In Embodiment 1, instead of the piping system shown in FIG. 2, the piping system shown in FIG. 1 (the distance between the piping a and the piping b is 30 mm, the inner diameter of the piping is 13 m).
m, hole diameter 1.8 mm), the laminated plate is immersed in the central part between the piping a and the piping b, the electrodeposition bath B is used instead of the electrodeposition bath A, and the layers are laminated at the time of electrodeposition coating. The flow velocities of the bath liquid on the right end portion of the plate (pipe A, B side) in the parallel direction to the laminated plate and the flow velocity of the left end surface in the parallel direction to the laminated plate were 0.3 m / sec and 0, respectively. A photoresist film was formed in the same manner except that it was set to 0.2 m / sec. When each film thickness was measured in the same manner as in Example 1, the average film thickness and the difference between the maximum film thickness and the minimum film thickness were as shown in Table 1.

Comparative Example 3 A photoresist film was formed in the same manner as in Example 3 except that the electrodeposition bath was not circulated during electrodeposition coating and the flow rate of the bath liquid was set to 0. When each film thickness was measured in the same manner as in Example 1, the average film thickness and the difference between the maximum film thickness and the minimum film thickness are shown in Table 1.
It was as shown in.

[0049]

[Table 1]

As is clear from the data in Table 1, in Examples 1 to 3 according to the method of the present invention, a photoresist film having a uniform film thickness with a small difference between the maximum film thickness and the minimum film thickness was obtained. On the other hand, Comparative Examples 1 and 3 in which the bath liquid is not flowed in the direction parallel to the laminated plate.
And Comparative Example 2 in which turbulent flow was used, the difference between the maximum film thickness and the minimum film thickness was 3 μm or more.

[0051]

According to the electrodeposition coating method of the present invention, it is possible to form a photoresist film having a very uniform film thickness on the entire surface of a conductive substrate.

[Brief description of drawings]

FIG. 1 shows an example of a piping system installed in an electrodeposition bath used in the method of the present invention.

FIG. 2 is an example of a piping system installed in an electrodeposition bath used in the method of the present invention.

FIG. 3 is an example of a piping system installed in an electrodeposition bath used in the method of the present invention.

FIG. 4 is an example of a piping system installed in an electrodeposition bath used in the method of the present invention.

FIG. 5 is a system diagram showing an example of an electrodeposition coating apparatus used in a conventional electrodeposition coating method.

FIG. 6 is a schematic sectional view of an electrodeposition bath and an overflow bath used in Examples.

FIG. 7 is a schematic plan view of an electrodeposition bath and an overflow bath used in Examples.

[Explanation of symbols]

 1 Electrodeposition bath 2 Overflow bath 3 Conductive substrate 4 Electrode (stainless steel plate) 5 Piping 6 Circulation pump

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hideaki Uehara 4-13-1, Higashi-cho, Hitachi-shi, Ibaraki Hitachi Chemical Co., Ltd. Ibaraki Research Institute (72) Inventor Hitoshi Amano 4-13, Higashi-cho, Hitachi-shi, Ibaraki No. 1 Hitachi Chemical Co., Ltd. in Ibaraki Laboratory (72) Inventor Takuro Kato 4-13-1, Higashimachi, Hitachi City, Ibaraki Prefecture Hitachi Chemical Co., Ltd. in Yamazaki Plant (72) Inventor Katsushige Tsukada Hitachi City, Ibaraki Prefecture 4-13-1 Higashimachi Hitachi Chemical Co., Ltd. Yamazaki factory (72) Inventor Shoji Yamada 1382-12 Shimoishigami, Otawara-shi, Tochigi Dainippon Paint Co., Ltd. Nasu factory (72) Inventor Yuji Yamazaki Tochigi prefecture 1382-12 Shimoishigami, Otawara City Dainippon Paint Co., Ltd.Nasu Plant (72) Inventor Toshihiko Shiotani 1382-12 Shimoishigami, Otawara City, Tochigi Prefecture Dainippon Paint Co., Ltd. Company Nasu in the factory (72) inventor Yoshihisa Nagashima Tochigi Prefecture Otawara Shimoishigami 1382 No. No. 12 Dai Nippon Paint Co., Ltd. Nasu in the factory

Claims (1)

[Claims] 1. In an electrodeposition coating method of immersing a conductive substrate in an electrodeposition bath for photoresist to form a photoresist film on the surface of the substrate, in the vicinity of the surface of the substrate immersed in the electrodeposition bath, and An electrodeposition coating method characterized by performing electrodeposition coating while flowing a bath liquid in a direction parallel to the substrate at a flow rate of 0.05 to 2 m / sec.