JPH03120785A - Manufacture of printed-wiring board - Google Patents

Abstract

PURPOSE:To enable an improved dispersion stability and film appearance of an electrodeposition liquid to be maintained continuously by stirring the electrodeposition liquid in an air where a carbon dioxide is eliminated at the time of performing electrodeposition painting. CONSTITUTION:A light-sensitive film is subjected to electrodeposition/painting to a printed-wiring board with copper foil or copper plating. Carbon dioxide within air can be eliminated, for example, by the absorption method into an alkali aqueous solution. Also, when absorbing carbon dioxide, substances adversely affecting the electrodeposition painting such as dust can be eliminated simultaneously. Air where carbon dioxide is eliminated can be used again, thus preventing an electrodeposition bath from being deteriorated and the performance of the light-sensitive film obtained from electrodeposition from being reduced. Therefore, the succeeding processes can be advanced smoothly and an improved printed-wiring board can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a manufacturer of printed wiring boards (prior art) Conventionally, when manufacturing printed wiring boards.

First, a layer of a photocurable resin composition is formed on a substrate.

Then, actinic light is irradiated in an imagewise manner, and the uncured portions are developed and removed to form a resist pattern.

In this step, various methods are employed to form the layer of the photocurable resin composition. For example, methods using a photocurable resin composition solution (coating liquid) such as dip coating, roll coating, and curtain coating.

Alternatively, a method is known in which films of photocurable resin compositions (photosensitive films) are laminated. Among these methods, the method of laminating photosensitive films is currently adopted as the mainstream method because it can easily form a layer of a photocurable resin composition with a uniform thickness.

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.

This method has poor ability to follow irregularities on the substrate surface caused by dents during substrate manufacturing, nonuniform polishing, and nonuniformity of copper plating bits on the surface of the mesh 9 of the glass cloth in the inner layer of the substrate. , it is difficult to obtain sufficient adhesion. This difficulty can be solved by laminating the films under reduced pressure (Tokuko Kokō 5).
(see Japanese Patent No. 9-3740), this can be avoided, but this requires special and expensive equipment.

For these reasons, in recent years, solution coating methods such as dip coating, roll coating, and curtain coating have become more glossy.

However, these coating methods have problems such as difficulty in controlling the film thickness, insufficient uniformity of the film thickness, and occurrence of pinholes.

Recently, a new method of forming a photoresist film by electrodeposition coating has been proposed (Japanese Patent Laid-Open No. 62-23549).
(See Publication No. 6). According to this method, (1) the adhesion of the resist is improved; ■Good followability to irregularities on the substrate surface, ■
A photoresist film with uniform thickness can be formed in a short time. ■Because the coating liquid is an aqueous solution.

It has advantages such as preventing contamination of the working environment and causing no problems in terms of disaster prevention.

(Problem to be Solved by the Invention) By the way, when electrocoating a photoresist film, the clear liquid is usually a dispersion system with a solid content of 20% or less.
Stirring is important to prevent sedimentation. Stirring has the effect of reducing local concentration of electrolytic gas, which causes damage to the electrodeposited coating film, and the air agitation method using air jets has a simple structure and the stirring efficiency is not so bad.

However, when the electrodeposition solution is air-stirred for a long time, the amine in the electrodeposition solution is consumed by carbon dioxide in the air, the pH decreases, and the dispersion of the electrodeposition coating resin composition and the appearance of the coating film deteriorate. There was a problem.

(Means for Solving the Problems) As a result of various studies to overcome the drawbacks of the above-described air agitation method for electrodeposition liquid, the inventors of the present invention have made the following.

It has been discovered that by stirring the electrodeposition solution with air from which carbon dioxide has been removed during electrodeposition coating, it is possible to continuously maintain good dispersion stability and coating film appearance of the electrodeposition solution.

That is, the present invention provides a method for manufacturing a printed wiring board by forming a photosensitive film by electrodeposition, in which an electrodeposition bath containing a photosensitive resin is stirred with air from which carbon dioxide has been removed, and then copper foil or copper plating is applied. The present invention relates to a method for manufacturing printed wiring, characterized by electrodepositing a photoresist film on a printed circuit board.

Carbon dioxide in the air can be removed by, for example, absorption into an aqueous alkaline solution. Further, when absorbing carbon dioxide, it has the effect of simultaneously removing substances such as dust without adversely affecting the electrodeposition coating.

In the present invention, the air from which carbon dioxide has been removed can be recycled and reused. Specific examples will be shown below using Examples and Comparative Examples.

(Example) Example 1 First, methacrylic acid/methyl methacrylate/ethyl acrylate/octyl acrylate (20150/20/10
Weight ratio) 50% by weight of copolymer (molecular weight 70,000)
130 parts by weight of dioxane solution, 20 parts by weight of trimethylolpropane triacrylate.

A mixed solution of 10 parts by weight of 5-tetraethylene glycol diacrylate was neutralized using 0.6 equivalents of triethylamine, 3 parts by weight of benzophenone as a photopolymerization initiator, 1 part by weight of Michler's ketone, and 0 parts by weight of hydroquinone as a stabilizer. After adding .5 parts by weight and a solution of 0.2 parts by weight of Victoria Pure Blue as a coloring agent dissolved in 10 parts by weight of methyl ethyl ketone, the solid content was 10% by weight.
Water was added to make an electrodeposition coating bath (pH 9).

The electrodeposition tank was made using 5Qwt% hydroxide) Air, which had been passed through an IJium aqueous solution to remove carbon dioxide, was blown into the electrodeposition solution at a rate of about 101/min from an air pipe attached to the bottom of the electrodeposition solution tank. The structure was designed to stir the electrodeposition solution. in an electrodeposition bath under the same conditions.

Coating was carried out using the electrodeposition bath 0 and 1.24 hours after air stirring was started, respectively.

The conditions for electrodeposition were as follows: A copper-clad laminate (MCL-E-61 manufactured by Hitachi Chemical Co., Ltd.) with a polished surface was used as the anode.

A stainless steel plate (8U8-304) is used for the cathode.

Row A was completed in 3 minutes with an applied voltage of 150V.

6- In addition, the electrodeposition solution was sampled immediately before electrodeposition, and was filtered through a filter to examine the presence or absence of sediment.

After electrodeposition is complete, remove the substrate from the electrodeposition bath and wash with water.

Drying was performed (80°C, 5 minutes). Next, I used a 3kW ultra-high pressure mercury lamp (HMW-201B manufactured by Oak).

300 mJ/cm'' was irradiated through the negative film.

After irradiation, the film was developed with a 1 wt % Na2COs aqueous solution, and the exposed copper surface was etched with a cupric chloride aqueous solution.

Finally, the coating film on the unexposed area was peeled off with a 3 wt % NaOH aqueous solution to produce a good printed wiring board.

Comparative Example 1 Printed out in the same manner as in Example except that air without removing carbon dioxide was used in the electrodeposition process ○ No sediment △ Slight sediment observed × Kana υ sediment observed (Effects of the Invention) The present invention prevents deterioration of the electrodeposition bath by stirring the electrodeposition solution using air excluding carbon dioxide.

Since the performance of the photoresist film obtained by electrodeposition is not deteriorated, the subsequent steps proceed smoothly and a good printed wiring board can be obtained.

Claims (1)

[Claims] 1. In the method of manufacturing printed wiring boards by forming a photosensitive film by electrodeposition coating, an electrodeposition bath containing a photosensitive resin is stirred with air from which carbon dioxide has been removed, and a copper foil or copper-plated board is coated with the electrodeposition bath. A method for producing a printed wiring board characterized by electrodepositing a photosensitive film.