JPH03230593A - Manufacture of printed wiring board - Google Patents

Abstract

PURPOSE:To reduce the time of an electrodeposition by specifying current values for an initial time and a remaining time in the whole electrifying time for the electrodeposition and performing the electrodeposition. CONSTITUTION:A photosensitive resin is electrodeposited on a printed wiring board to form a photosensitive resist film and the printed circuit board is manufactured via exposure, developing and etching processes. In this case, an electrodeposition is performed by letting a 30-80mA/dm<2> current flow within the initial time of 1/3-1/2 the whole electrifying time for the electrodeposition and letting the current 1.5-2.5 times the initial current value mentioned above within the remaining time. A photosensitive electrodeposition paint composition part is fundamentally a composite containing a resin with a salt forming radical and a photosensitive radical for making water-soluble or water-dispersive as a main component. Thus, the time of the electrodeposition for forming the photosensitive resist film can be reduced and a productivity can be improved.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a method for manufacturing a printed wiring board, and more specifically, the present invention relates to a method for manufacturing a printed wiring board, and more specifically, it improves productivity by shortening the electrodeposition coating time for forming a photosensitive resist film. The present invention relates to a method of manufacturing a printed wiring board with the purpose of improving the performance.

[Prior art and its problems] A method of manufacturing a printed wiring board by electrocoating a photosensitive resin onto a printed wiring board is already known (for example, US Pat. Nos. 3,954,587, 4,592,816, and 4,632).
No. 900, No. 4673458, JP-A-60-20713
No. 9, JP-A-61-206293, JP-A-63-60
(See Publication No. 70, etc.).

Characteristics of the method for manufacturing printed wiring boards by electrodeposition coating include the possibility of automation and the ability to obtain a uniform film, making it an excellent method as an industrial manufacturing method. However, it is desired to further improve productivity. In electrodeposition coating, in order to shorten the coating time, it is possible to make the tank thicker so that multiple substrates can be coated at the same time, or to shorten the current application time. In the method of painting multiple boards,
As the equipment becomes larger, the cost also increases. In addition, the electrodeposition tank is thick (which makes maintenance of the bath paint and management of turnover complicated).Also, in order to shorten the current application time, it is necessary to apply a large current to reduce the amount of resin deposited. However, at the same time, the amount of gas generated from the surface of the object to be coated (substrate) also increases, making it easier for pinholes and craters to occur in the painted photosensitive resist film, resulting in a significant deterioration of the finish. arise.

[Means for Solving the Problems] As a result of intensive research to solve these problems, the present inventors have found that in the process of electrodeposition coating photosensitive resin, the entire current flow for electrodeposition coating is During the initial turbulent period, paint with a constant current within the range of 30-80 mA/dm2, and during the remaining turbulent period, apply at 15-2% of the initial current value. It was discovered that by performing electrodeposition coating by applying a current of 5 times the range, the time for electrodeposition coating was significantly shortened, and the resulting photosensitive resist film had a good finish, and the present invention was completed. reached.

Thus, according to the present invention, in the method of manufacturing a printed wiring board by electrodepositing a photosensitive resin on a printed wiring board to form a photosensitive resist film, and then performing the steps of exposure, development, and etching, 30 to 80 mA/dm during the initial % of the total energizing time for painting.
A method for manufacturing a printed wiring board is characterized in that a current of 1.5 to 2.5 times the initial current value is applied during the remaining % to % of the time to perform electrodeposition coating. provided.

The present invention will be explained in detail below.

The photosensitive electrodeposition coating composition used in the method of the present invention is basically a composition containing as a main component a resin having a salt-forming group and a photosensitive group to make it water-soluble or water-dispersible. Compositions can be classified into negative-type electrodeposition coating compositions and positive-type electrodeposition coating compositions. Typical examples are shown below.

Negative Sensation S, Ill: A conventionally known anionic or cationic electrodepositable composition containing a water-soluble or water-dispersible polymerizable unsaturated resin and a photopolymerization initiator as main components. The polymerizable unsaturated resin used in the composition is not particularly limited as long as it is a water-soluble or water-dispersible resin containing an anionic or cationic group (typical examples include anionic or water-dispersible resins). Examples of the resins include those listed in (1) to (5) below.

(1) - A polymerizable unsaturated resin obtained by adding a reaction product of a compound having a polymerizable unsaturated bond and a hydroxyl group in the molecule and a diisocyanate compound to a high acid value acrylic resin having a hydroxyl group in the resin skeleton, Or, a resin composition whose main component is a combination of these and an ethylenically unsaturated compound having one or more polymerizable unsaturated bonds in the molecule: (
2) α・
The main component is a mixture of a polymerizable unsaturated resin obtained by adding β-ethylenically unsaturated dibasic acid or its anhydride and an ethylenically unsaturated compound having one or more polymerizable unsaturated bonds in one molecule. Resin composition: (3) Main component is a mixture of a polymerizable unsaturated resin consisting of an unsaturated fatty acid-modified high acid value alkyd resin and an ethylenically unsaturated compound having one or more polymerizable unsaturated bonds in one molecule. Resin composition: (4) A resin composition whose main component is a mixture of a polymerizable unsaturated resin consisting of maleated oil and an ethylenically unsaturated compound having one or more polymerizable unsaturated bonds in one molecule. (5) - A polymerizable unsaturated resin obtained by adding a compound having a polymerizable unsaturated bond and a glycidyl group in the molecule to a high acid value acrylic resin, or a polymerizable unsaturated resin containing these and - a polymerizable unsaturated bond in the molecule. A resin composition whose main component is one in which one or more ethylenically unsaturated compounds are used in combination: Representative examples of cationic resins include (6) below.
- (10) can be mentioned.

(6) - Polymerizable unsaturated product obtained by adding a reaction product of a compound having a polymerizable unsaturated bond and a hydroxyl group in the molecule and a diisocyanate compound to an acrylic resin having a hydroxyl group and a tertiary amino group in the resin skeleton. Resin: (7) - After partially reacting the epoxy groups of an epoxy resin having two or more epoxy groups in the molecule with a compound containing a secondary amino group, the remaining epoxy groups are reacted with (meth)acrylic acid, etc. A tertiary amino group-containing unsaturated resin obtained by reacting with a polymerizable unsaturated monocarboxylic acid or a compound having a polymerizable unsaturated group and a hydroxyl group in one molecule: (8) - A polymerizable unsaturated group and a hydroxyl group in one molecule: Compounds having a glycidyl group (e.g. glycidyl (meth)acrylate) and compounds having a polymerizable unsaturated group and a tertiary amino group in the molecule (e.g. N,N-dimethylaminoethyl (meth)
Acrylate, N.

N-diethylaminoethyl (meth)acrylate, N,
N-dimethylaminopropyl (meth)acrylate, etc.) is copolymerized with other polymerizable monomers to obtain a resin (
Tertiary amino group-containing unsaturated resin obtained by reacting a monocarboxylic acid having a polymerizable unsaturated group such as meth)acrylic acid or a compound having a polymerizable unsaturated group and a hydroxyl group in one molecule: (9) Epoxy The epoxy groups of the resin are partially reacted with a compound having a polymerizable unsaturated group and a carboxyl group or a hydroxyl group in the molecule, and then the remaining epoxy groups are reacted with a tertiary amino compound, thioether, phosphine, etc., and a carboxylic acid. Onium base-containing unsaturated resin obtained by onium salt conversion: (10) Instead of partially esterifying the epoxy group in (9) above and then converting it into onium salt, - a polymerizable unsaturated group in the molecule An onium base-containing unsaturated resin obtained by simultaneously reacting an epoxy resin with a compound having a carboxyl group or a hydroxyl group, an onium salt-forming compound such as the above-mentioned tertiary amine group-containing compound, and a carboxylic acid; etc.

These resins can be used alone or in combination of two or more.

The anionic or cationic polymerizable unsaturated resin represented by (1) to (10) above has a carboxyl group content (in the case of anionic type) of 20 to 300 (preferably 40 to 110) in terms of acid value, Tertiary amino group and/or onium base content (in case of cation type) is 0 per 1 kg of resin.
．． 2 to 5 mol (preferably 0.3 to 2.0 mol), unsaturation equivalent of 150 to 3.000 (preferably 150 to 1
．． 000) and a number average molecular weight of 300 or more (preferably 1.000 to 30.000).

In addition, the glass transition temperature of the polymerizable unsaturated resin when not exposed to light (
Advantageously, the Tg (hereinafter referred to as Tg) is in the range of -50 to 60°C (preferably -20 to 40°C). Tg
If it is below 150℃, the coating film during electrodeposition will be too soft and the film resistance will be low, making it difficult to obtain a uniform coating.On the other hand, if the Tg is 60℃
If it is more than that, the film resistance increases, making it difficult to obtain a thick film, and chain transfer is difficult to occur during exposure, resulting in poor photosensitivity.

The photopolymerization initiator used in combination with the unsaturated resin in the present invention is not particularly limited as long as it can initiate radical polymerization with actinic rays such as ultraviolet rays, and typical examples include: Benzoin, benzoin methyl ether, benzoin ethyl ether, benzyl, diphenyl disulfide, tetramethylthiuram monosulfide, diacetyl, niosin, thionin, Michler's ketone, anthraquinone, chloranthraquinone, methylanthraquinone, α-hydroxyisobutylphenone, p-isopropyl α-hydroxyisobutylphenone , α・α′ dichloro-4-phenoxylacetophenone, l-hydroxyl-cyclohexylacetophenone, 2,2-dimethoxy2-phenylacetophenone, methylbenzoylformate, 2-methyl-1-[4-
(Methylthio)phenyl] ・2. Morpholino-propene, thioxanthone, benzophenone, etc. can be mentioned, and the usage amount of these is resin component (solid content) 100
A good range is 0.1 to 10 parts by weight (0,1 parts by weight).
If the amount is less than 10 parts by weight, the curability decreases, which is undesirable, and if it is more than 10 parts by weight, the mechanical strength of the cured film tends to deteriorate.

In the anionic unsaturated resins (1) to (5) described above, examples of ethylenically unsaturated compounds having one or more polymerizable non-enclosing bonds in one molecule used as an essential component or an optional component include medyl ( Esters of (meth)acrylic acid such as meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, and butyl (meth)acrylate; polyfunctional monomers such as ethylene glycol di(meth)acrylate and divinylbenzene; Examples include styrene, (meth)acrylonitrile, and the like.

Positive coating composition: In the present invention, the positive electrodeposition coating composition used to form the positive photoresist is one conventionally known in the art, and may be either anionic or cationic. For example, a polyoxymethylene polymer having a salt-forming group and a photosensitive group to make it water-soluble or water-dispersible, 0-nitrocarbinol ester, O-nitrophenyl acecool, a resin containing a benzo (or naphtho) quinone diazide unit, etc. (For example, JP-A-60-207139, JP-A-61-206293, JP-A-63-1999)
6070, Japanese Patent Application No. 157841/1982, Japanese Patent Application No. 157842/1982, Japanese Patent Application No. 245840/1982,
(See Japanese Patent Application No. 62-279288, etc.).

The resin having a salt-forming group and a photosensitive group used in the above-mentioned positive type i@ coating composition contains 5 to 60% by weight (preferably (10 to 50% by weight), the acid value, tertiary amine group and/or onium base content, number average molecular weight, and Tg are as specified in (1) to (10) above.
It is the same as unsaturated resin represented by.

In addition to the above-mentioned anionic or cationic resin as a resin binder, the negative or positive electrodeposition coating composition used in the present invention includes a polymerizable unsaturated group-containing resin (
For example, polyester acrylate containing ethylenically unsaturated groups, polyurethane resin, epoxy resin, acrylic resin, etc.), saturated resin (for example, polyester resin, polyurethane resin, epoxy resin, acrylic resin, etc.), oligomer (for example, diethylene glycol di(meth)acrylate) etc.), etc., per 100 parts by weight of resin.
It is also possible to adjust the coating film performance appropriately by blending in an amount of not more than 50 parts by weight, preferably not more than 50 parts by weight.

Water solubilization or water dispersion of the resin when preparing an electrodeposition coating composition involves neutralizing the acid groups with an alkali (neutralizing agent) if acid groups such as carboxyl groups are introduced into the resin skeleton. This is carried out by neutralizing with an acid (neutralizing agent) if an amine group is introduced.

Examples of alkali neutralizing agents include monoethanolamine,
Alkanolamines such as jetanolamine and triethanolamine, alkylamines such as triethylamine, diethylamine, monoethylamine, diisopropylamine, trimethylamine, and diisobutylamine, alkylalkanolamines such as dimethylaminoethanol, and alicyclic groups such as cyclohexylamine. Examples of acid neutralizers include amines, alkali metal hydroxides such as caustic soda and caustic potash, and ammonia. Examples of acid neutralizers include monocarboxylic acids such as formic acid, acetic acid, lactic acid, hydroxyacetic acid, and butyric acid. These can be used alone or as a mixture. The amount of the neutralizing agent used is preferably in the range of 0.2 to 1.0 equivalents per mole of salt-forming groups contained in the skeleton.

In order to further improve the fluidity of the water-solubilized or water-dispersed resin component, a hydrophilic solvent, such as impropatol,
N-butanol, t-butanol, methoxyethanol, ethoxyethanol, butoxyethanol, diethylene glycol, methyl ether, dioxane, tetrahydrofuran, etc. can be added. The amount of the hydrophilic solvent used is preferably 300 parts by weight or less per 100 parts by weight of the vehicle component.

In order to increase the amount of coating on the object, hydrophobic solvents such as petroleum solvents such as toluene and xylene; ketones such as methyl ethyl ketone and methyl isobutyl ketone; esters such as ethyl acetate and butyl acetate: 2-ethylhexyl Alcohols such as alcohol; etc. can also be added. The amount of the hydrophobic solvent used is preferably 200 parts by weight or less per 100 parts by weight of the resin component.

For example, a copper clad laminate, for example λ, is immersed in this electric bath as a substrate,
Painting is usually carried out by applying a direct current of 20 to 400V. In the case of anionic electrodeposition coating, the substrate is used as an anode, and in the case of cationic electrodeposition coating, the substrate is used as a cathode. The appropriate current application time is usually about 15 seconds to 5 minutes. The resulting film thickness is about 5 to 60 F, preferably 10 to 30 pm. After that, wash with water and blow with air if necessary.

Next, a pattern mask is formed on the photosensitive electrodeposition coating film formed on the substrate and exposed to actinic light such as ultraviolet rays.

When the photosensitive electrodeposition coating film is of negative type, the actinic rays are irradiated only on the portions that should be used as conductor circuits, and when the photosensitive electrodeposition coating film is of positive type, only unnecessary portions other than the conductor circuits are irradiated with actinic rays.

In the present invention, the actinic rays used for exposure are generally 3,
A light beam having a wavelength of 0.000 to 4,500 is preferable. These light sources include sunlight, mercury lamps, xenon lamps, arc lamps, and laser beams, and examples of mercury lamps used include high-pressure mercury lamps, ultra-high-pressure mercury lamps, metal halide lamps, and chemical lamps. The coating film is cured by irradiation with actinic light within several minutes, usually within a range of 1 second to 20 minutes.

In addition, development treatment is performed by spraying weak alkaline water onto the coating surface if the electrodeposition paint is anionic, or by spraying an acid aqueous solution with a pH of 5 or less if the electrodeposition paint is cationic. This can be done by washing away the hardened area.

Weakly alkaline water is usually caustic soda, soda carbonate, caustic potash, ammonia water, amine water, and sodium silicate, etc.
Those that can neutralize the free carboxylic acid present in the coating film and make it water-soluble can be used. In the case of a negative type, the unexposed area is washed away, and in the case of a positive type, the exposed area is washed away.

If the electrodeposited coating is positive, the surface temperature should be increased to 1 before the development process.
By performing heat treatment at a temperature of 00° C. to 180° C., preferably 120° C. to 160° C. for 1 second to 30 minutes, the unexposed portions are promoted to be less soluble in alkali, and the resolution of the pattern is further improved. You can also include this step.

Development in the case of cationic electrodeposition is carried out by spraying or immersing in weakly acidic water to wash away the uncured areas (negative type) and exposed areas (positive type) of the coating film. It will be done. The weakly acidic water that can be used is usually hydrochloric acid, phosphoric acid, acetic acid, formic acid, lactic acid, etc., which can neutralize amino groups released in the coating film and make it water-soluble. Of course, it is also possible to develop using a solvent or the like.

Next, the exposed copper foil portion (
Non-circuit portions) can be removed, for example, by ordinary etching treatment using a ferric chloride solution, cupric chloride solution, etc. in the case of an anion type, or an alkaline solution, etc. in the case of a cation type. Thereafter, the photocured coating film or unexposed coating film on the circuit pattern is treated with a cellosolve solvent such as ethyl cellosolve or ethyl cellosolve acetate; toluene,
Aromatic hydrocarbon solvents such as xylene; Ketone solvents such as methyl ethyl ketone and methyl isobutyl ketone; Acetate ester solvents such as ethyl acetate and butyl acetate; Chlorine solvents such as trichlorethylene or 2 to 10% caustic soda, caustic potash, etc. A printed circuit can be formed on the substrate by dissolving and removing it with an aqueous solution (acid aqueous solution in the case of cationic electrodeposition paint).

[Example] [Example] Next, the present invention will be described in more detail based on Examples. In the examples, "parts" and "%" indicate "parts by weight" and "wt% j," respectively.

Example 1 A mixed solution consisting of 400 parts by weight of methyl nucleate, 400 parts by weight of butyl acrylate, 200 parts by weight of acrylic acid, and 20 parts by weight of azobisisobutyronitrile was heated to 110° C. under a nitrogen gas atmosphere. Glycol monomethyl ether (hydrophilic solvent) 900
After dropping one drop into a part by weight over a period of 3 hours, it was aged for 1 hour, and a mixed solution consisting of 10 parts by weight of azobisdimethylvaleronitrile and 100 parts by weight of propylene glycol monomethyl ether was added dropwise over a period of 1 hour. A high acid value acrylic resin (acid value 155) solution was obtained by further aging for 5 hours.
parts by weight, 1.2 parts by weight of hydroquinone and 6 parts by weight of tetraethylammonium bromide and reacted at 110°C for 5 hours while blowing air to obtain an unsaturated resin (acid value 50, degree of unsaturation 1, 35 mol/kg). (D?
8 liquid ■ was obtained.

After sufficiently neutralizing 67 parts by weight of triethylamine to 2,270 parts by weight of unsaturated resin solution, 60 parts by weight of photopolymerization initiator a-hydroxyisobutylphenone was added and mixed to obtain a solid content of 15 parts by weight. Deionized water was added to make an electrodeposition coating bath (pH 6, 7) so as to adjust the weight %.

Using this electrodeposition coating bath, a copper-clad substrate for a printed wiring board was used as an anode, a slow start was performed for 10 seconds at a bath temperature of 25°C, and after 10 seconds, electricity was applied for 50 seconds at a current density of 50 mA/dm2. Then, the current density was increased to 100 mA/dm.
2 and energized for 1 minute. The total energization time was 2 minutes. This coating film was washed with water and dried at 80° C. for 10 minutes, and the resulting coating film had a thickness of 1 Bpm and had a good finish. When current was applied at 50 mA/dm2, 3 minutes and 40 seconds were required to obtain this film thickness.

100 mA/dm2 after 10 seconds of slow start
In the photosensitive resist films obtained by coating for 75 seconds, 90 seconds, and 120 seconds at current values of , many pinholes due to gas generation were observed. Regarding these photosensitive resist films,
A negative pattern mask film was placed on the resist film, degassed under vacuum, and exposed to light at 200 mJ/cm 2 using an ultra-high pressure mercury lamp.

Next, development was carried out using a 1% sodium carbonate solution at 25° C. for 40 seconds, and after washing with water, etching treatment was carried out with in-situ copper to obtain a pattern circuit.

The board that was initially electrodeposited at 50 mA/dm" had a size of 1010x1o after etching and had no pinholes, but it was coated for 75 seconds, 90 seconds, and 120 seconds at a current density of 100 mA/dm". 13 pinholes, 11 pinholes, and 12 pinholes were observed on the prepared substrates, respectively.

Example 2 A mixed solution of 600 parts by weight of styrene, 100 parts by weight of methyl acrylate, 200 parts by weight of acrylic acid and 30 parts by weight of azobisisobutyronitrile was heated to 1.20°C under a nitrogen gas atmosphere using Cellosolve 900. It was added dropwise to the weight part over a period of 3 hours. After dropping, it was aged for 1 hour, and a mixed solution consisting of 10 parts by weight of azobisdimethylvaleronitrile and 100 parts by weight of cellosolve was added dropwise over 1 hour, and aged for another 5 hours to form a high acid value acrylic resin (acid value 233) solution. I got it. Next, 350 parts by weight of glycidyl methacrylate, 1.3 parts by weight of hydroquinone and 6 parts by weight of tetraethylammonium bromide were added to this solution, and the mixture was reacted at 110°C for 5 hours in a conventional manner while blowing air. Value 70, degree of unsaturation 1.8
3 mol/kg) solution ■ was obtained.

85 parts of triethylamine in 2,400 parts of unsaturated resin solution
Parts by weight were added to sufficiently neutralize.

Next, 400 parts by weight of isobutyl alcohol and 70 parts by weight of photopolymerization initiator benzoin ethyl ether were added, and then deionized water was added so that the solid content was 13% to prepare an electrodeposition coating bath.

Specific conductivity was 1.350 μs/cm.

A through-hole plated copper-clad laminate was used as an anode, and at a bath temperature of 30°C, the current value was kept constant for 8 seconds at a current density of 60 mA/dm, and the current was applied for 42 seconds.Then, the current value was increased to 120 mA/dm. ” and energized for 60 seconds. The total energization time was 110 seconds. The film thickness of the resist obtained by washing with water and drying (90°CXl 0 minutes) is 2
0 mm, and the finish was good.

When current was applied at 60 mA/dm2 to obtain this film thickness, a time of 180 seconds was required.

After 8 seconds of slow start, the current value was increased to 120 mA/dm2, and electrodeposition coating was performed at constant current for 60 seconds, 80 seconds, and 100 seconds, respectively. All of these resist films had pinholes and small letters.

For these resist films, a negative pattern mask film was placed on top of the resist, vacuum degassed, and exposure was performed using a metal halide lamp at 350 mJ/cm2.

The exposed plate was then developed with a 1% sodium carbonate solution for 50 seconds, washed with water, and etched with copper chloride to obtain a through-hole pattern circuit.

II electrodeposition coating with an initial current of 60 mA/dm" and an initial current of 60 mA/dm" and a second half of 120 mA.
/ dm", the plate had a size of 1010 x 1 O after etching, no pinholes were observed, and through holes were well formed.

However, at 120 mA/dm”, 60 seconds, 80 seconds, 1
The one painted for 00 seconds is 10cmx after etching.
10 pinholes, 7 pinholes, and 9 pinholes were observed on each 10 cm plate, and through-hole formation was also insufficient.

Example 3 400 parts of methyl isobutyl ketone was placed in a four-roof flask, heated to 80"C without stirring, and then heated to tert.
- A mixed solution of 240 parts of butylaminoethyl methacrylate, 400 parts of methyl acrylate, 50 parts of acrylic acid, and 35 parts of azobisisobutyronitrile was added dropwise over 3 hours, and after keeping for 1 hour, 80 parts of methyl isobutyl ketone,
1 of a mixed solution of 10 parts of azobisdimethylvaleronitrile
The mixture was added dropwise over time, kept for 2 hours, and then the temperature was lowered to 40°C. Furthermore, a mixed solution of 270 parts of orthonaphthoquinonediazide sulfonic acid chloride and 630 parts of dioxane was added to the
The mixture was added dropwise over time and kept for 2 hours to obtain a positive photosensitive resin.

Add 20% ethylene glycol monomethyl ether to this resin.
0 parts and 60 parts of dimethylethanolamine were added to sufficiently neutralize the solution, and then deionized water was added so that the solid content was 12% to prepare an electrodeposition bath (pH 6.8).

The copper-clad board is used as an anode, the bath temperature is 23℃ and 50mA/dm.
”, the current value was kept constant for 5 seconds, and 35
Power was applied for seconds.

Then, increase the current value to 120 mA/dm” and
Electricity was applied for a second. The total energization time was 110 seconds.

The film thickness of the resist obtained by washing with water and drying at 85° C. for 10 minutes was 8P, and the finished state was good.

When electricity was applied at 50 mA/dm2 to obtain this film thickness, a time of 220 seconds was required.

Under similar conditions, when the initial current value was 120 mA/dm2 and the coating was applied for 70 seconds, 90 seconds, and 110 seconds, many pinholes were generated.

For these resist films, a positive pattern mask film was placed on the resist film, and vacuum degassing was performed.
Exposure was performed by irradiating ultraviolet rays of 300 mJ/cm'' with an ultra-high pressure mercury lamp.

Next, development was performed with sodium metasilicate, and after washing with water, etching treatment was performed with copper chloride to obtain a pattern circuit. For those electrodeposited with an initial current value of 50mA/dm'' and those electrodeposited with an initial current value of 50mA/dm'' and a later current value of 120mA/dm'', 1010X1 is applied after etching.
No pinholes were observed on the board with a size of 0.

However, in all cases coated with a current density of 120 mA/dm2 from the initial stage, ten or more pinholes were observed on a 10 cm x 10 cm substrate.

Claims (1)

[Claims] In the method of manufacturing a printed wiring board by electrocoating a photosensitive resin onto a printed wiring board to form a photosensitive resist film, and then performing exposure, development, and etching processes, the total current application time for electrocoating is During the initial 1/3 to 1/2 time, a current of 30 to 80 mA/dm^2 is applied, and during the remaining 1/2 to 2/3 time, a current of 1.
A method for manufacturing a printed wiring board, characterized in that electrodeposition coating is carried out by applying a current of 5 to 2.5 times.