JPS6384191A - Manufacturing method of through-hole printed wiring board - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for manufacturing a through-hole printed wiring board. A high-performance through-hole plated wiring board can be manufactured with virtually no product defects.

[Conventional technology]

As a method for forming an etching resist in a method for manufacturing a through-hole printed wiring board, a method has been proposed in which the etching resist is formed by electrodeposition coating. This method is the most conventional etching resist formation method (hole filling method, tenting method, solder stripping method, etc.)
It has the advantage that an etching resist can be formed extremely easily compared to the conventional method.

[Problem that the invention seeks to solve]

However, electrodeposition coating has traditionally been used to paint automobile bodies, etc., and no precise coating has been devised. When used to form an etching resist, the thickness of the electrodeposited resin film may increase abnormally in some areas, causing the electrodeposition resin film to overlap between patterns, or conversely, in some areas the electrodeposition coating + 14 resin film may overlap. The film thickness becomes extremely small and the electrodeposited resin film peels off due to lack of adhesion, and gas bubbles generated on the coated surface remain in the electrodeposition resin film, causing pinholes. However, it is difficult to form an etching resist (electrodeposition coating resin film) with high precision.

Therefore, an object of the present invention is to solve the above-mentioned problems that occur when forming an etching resist by electrodeposition coating, and to manufacture high-performance through-hole plated wiring boards without substantially causing product defects. An object of the present invention is to provide a method for manufacturing a through-hole printed wiring board.

[Means for solving problems]

As a result of various studies, the inventors of the present invention determined whether electrodeposition paint should be used during electrodeposition coating. It has been found that the above-mentioned problems can be solved and the above-mentioned objects can be achieved by flowing the 8 liquid at a specific speed.

The present invention has been made based on the above findings, and it is possible to form an electrodeposited resin film in a pattern to be obtained by electrodeposition coating on a double-sided copper-clad substrate electrically conductive through the copper plating layer of the through holes. The present invention provides a method for manufacturing a through-hole printed wiring board, which is characterized in that a coating solution is made to flow at a flow rate of 0.1 to 50 cm/sec on a surface to be coated.

Hereinafter, the method for manufacturing the through-hole printed wiring board of the present invention will be described in detail.

The double-sided copper-clad board that is electrically conductive through the copper-plated layer of the through-hole used in the present invention is a thin plate made of an organic (resin) or inorganic insulating material, and a copper foil of a predetermined thickness is coated on both sides of the board by a conventional method. A double-sided copper-clad board with a copper-clad plate pasted with through-holes is drilled at specified locations, and then copper plating is applied to form a copper-plated layer on the hole wall of the through-hole and both sides of the copper-clad plate, or A resist coating layer with a reverse pattern is formed on the double-plated layers on both sides of a copper-clad plate by silk screen printing, photo development, or the like.

In addition, the resin paint used for electrodeposition coating in the present invention is a usual resin paint for electrodeposition coating, that is, an anionic resin paint (charged to (=) in water) that uses the object to be coated as an anode. and cationic resin materials (charged (+) in water) that use the object to be coated as a cathode.

The anionic resin is a water-soluble polymer compound that has a carboxyl group in its molecule, has a high acid value, and has the ability to react with bases such as ammonia, organic amines, and caustic alkalis to form salts. For example, maleated oil (maleated castor oil etc.), maleated liquid polybutadiene, maleated resin such as epoxy resin with ring-opened epoxy group with carboxylic acid and added maleic anhydride, phenol resin modified maleic. resin, resin obtained by halfestering maleated resin with alcohol,
Examples include alkyd resins, liquid polybutadiene resins having a terminal carboxyl group, styrene-7lyl alcohol resins, and acrylic resins.

In addition, as the above-mentioned cationic resin, for example, the epoxy group of an epoxy resin (epoxidized polybutadiene, etc.),
Examples include resins made water-soluble by addition and ring-opening with a primary or secondary amine and neutralization with an organic acid, resins made by partially ring-opening the epoxy resin with an amine, and then reacting with an organic acid. be able to.

Accordingly, in the method of manufacturing a through-hole printed wiring board, the present invention provides a method for applying electrodeposition coating to the substrate using the electrodeposition coating solution of the resin, and applying the electrodeposition coating solution to the surface to be coated, that is, the surface of the substrate. The flow rate is 0°1 to 50 cm/sec, preferably 0.5 to 20 cm/sec.

If the above flow rate is too low, bubbles of gas (hydrogen in the case of an electrodeposition paint solution made of a cationic resin, oxygen in the case of an electrodeposition paint solution made of an anionic resin) generated on the coated surface during electrodeposition coating. remains in the paint film and causes pinholes after the paint film is heated and hardened, resulting in corrosion of the copper layer of the circuit pattern during the etching process, and heat generated in the paint film and its vicinity during electric painting. Joule heat), the viscosity of the coating film decreases and the film thickness abnormally increases, causing the coating films to overlap between fine patterns, making it difficult to obtain an electrodeposited resin film with a predetermined pattern.

Furthermore, if the flow rate is too high, the coating film deposited on the surface to be coated may be redissolved by the electrodeposited coating material, or coagulation and deposition of the coating material may be hindered, resulting in an insufficient coating thickness. In particular, the film thickness is often insufficient at the edges of the substrate and through holes.

The flow of the electrodeposition paint solution is not particularly limited to any method as long as the flow velocity on the surface to be coated falls within the above range. This can be done by circulating a paint solution.

The apparatus shown in FIG. 1 includes an electrodeposition paint bath 1, an overflow tank 2 provided adjacent to the upper side of the electrodeposition paint bath 1, and a pump 3 that connects the electrodeposition paint bath 1 and the overflow tank 2. The electrodeposition paint bath 1 has a plurality of upward nozzles (not shown) arranged at regular intervals on the bottom thereof. Further, the electrodeposition paint bath 1 is configured such that when the electrodeposition paint solution in the tank 1 overflows, it flows into the overflow tank 2.
is supplied and circulated from the nozzle to the electrodeposition paint bath 1 by the pump 3 via the vibrator 4. Therefore, according to this apparatus, when performing electrocoating, the substrate to be electrocoated is immersed in the bath 1, the electrocoat bath 1 and the overflow bath 2 are filled with the electrocoat solution E, When the electrocoat solution E in the overflow tank 2 is supplied from the nozzle to the electrocoat bath 1 by the pump 3, the electrocoat solution E in the electrocoat bath 1 flows upward, and the electrocoat solution E in the electrocoat bath 1 flows upward. It flows into the overflow tank 2 and is supplied and circulated by the pump 3 through the vibrator 4 to the electrodeposition paint bath 1 from the nozzle. In this way, the electrodeposition paint solution E flows through the electrodeposition paint bath 1 and passes over the substrate surface at a predetermined flow rate. The flow rate of the electrodeposition paint solution can be adjusted by adjusting the overflow amount. The flow rate of the electrocoat solution when using the apparatus shown in Figure 1 is calculated by dividing the overflow amount of the electrocoat solution per unit time by the horizontal cross-sectional area of the electrocoat bath l. Ru.

Electrodeposition coating of the substrate in the present invention can be carried out according to a known method except for flowing the electrodeposition paint solution at the above-mentioned flow rate.
C, the applied voltage is 30 to 150V, especially 50 to 100V
It is preferable to carry out under the following conditions.

In the present invention, the treatment after performing the electrodeposition coating as described above may be carried out by 4 times more than the usual manufacturing method of through-hole printed wiring boards by electrodeposition coating, and as a result, the desired through-hole print can be achieved. A wiring board can be obtained.

For example, when a substrate on which a resist coating layer with a reverse pattern is formed is used as a substrate, after performing electrodeposition coating as described above to form an electrodeposition coating resin film, the resist coating layer with a reverse pattern is formed. The copper plating layer and the copper clad layer exposed by the removal of the resist coating layer are then removed by etching, and then the electrodeposited resin film is removed so that the copper plating layer in the through hole can be used to conduct electricity. A through-hole printed wiring board that is electrically conductive can be obtained.

In addition, if a substrate without a reverse pattern resist coating layer is used as a substrate, after electrodeposition coating, remove the electrodeposition coating resin film formed on both sides of the substrate, and then try to remove the electrodeposition coating resin film formed on both sides of the substrate. After forming a resist coating layer with a pattern to be formed, the copper plating layer and the copper clad layer in the areas where the resist coating layer is not formed are removed by etching. By removing the electrodeposited resin film, a through-hole printed wiring board in which four electrical connections are made by the copper plating layer of the through-holes is obtained.

〔Example〕

The present invention will be explained in more detail below by giving examples of manufacturing an electrodeposition paint solution and a substrate used in the electrodeposition coating of the present invention, and examples of the present invention.

Production Example 1 ``Ei'''' ■ 620 g of soybean oil fatty acid (acid value 155), rosin (acid value 1
70) 500g, tall oil fatty acid (acid value 170) 600
After reacting 140 g of linoleic acid, 140 g of linoleic acid, and 300 g of maleic anhydride at 200° C. under a nitrogen atmosphere for 3 hours, the mixture was cooled to 100° C., and 150 ml of xylene was added to the reaction solution.

Add 1000 g of pentaerythritol and 900 g of trimellitic anhydride and heat to 150°C again until the acid value reaches 10.
When the temperature reached 0, the reaction was stopped and cooled. During this time, xylene was removed under reduced pressure. Then, after cooling to 70℃,
680 g of isopropyl alcohol and 500 g of triethylamine were added and dissolved to obtain a modified alkyd resin solution with a solid content of about 70% by weight.

3 Add water-soluble melamine resin [Mitsui Toatsu Chemical special product, Kneepan 165 (non-volatile content: 7) to 100 g of the above modified alkyd resin solution.
0%)) and 2 g of a water-soluble silicone resin (manufactured by Toshi Silicone Co., Ltd., SH29PA) were added and mixed well, followed by 20 g of titanium oxide and 20 g of clay (each with an average particle size of 5%).
0 μm) and mixed well to obtain an electrodeposited resin composition.

Water is added to the above electrodeposited resin composition so that the nonvolatile content is 15%, and after dispersion in water, triethylamine is added so that the pH becomes 8.2, and alkyd resin type electrodeposition is performed. A chemical solution was obtained.

Manufacturing example 2 Glass epoxy double-sided copper clad board (35cm x 35cm.

After drilling 2,000 through holes with a hole diameter of 0.4 mm at specified locations in a 1.6 mm thick (1.6 mm thick) hole and applying copper plating to the hole walls of the through holes and the copper clad layer on both sides to form a copper plating layer. , print etching resist ink [manufactured by Sanei Chemical Co., Ltd., etching resist 5ER-4200] to form a resist coating layer with a reverse pattern, and then print the desired pattern (
Minimum width 100μm, pattern spacing 150. A substrate was obtained in which the copper plating layer of the cam) was exposed.

Example 1 Using the apparatus shown in FIG. 1, the alkyd resin type electrodeposition paint solution obtained in Production Example 1 was circulated, and the reverse electrodeposition paint solution obtained in Production Example 2 was added to the cough electrodeposition paint solution. The substrate on which the patterned resist coating layer was formed was immersed vertically. After adjusting the flow rate of the electrodeposition paint solution on the substrate surface to 1.0 cm and 7 seconds, a voltage of 70 V DC was applied to the substrate using the exposed copper part of the substrate as the anode and the stainless steel plate immersed in the electrodeposition paint solution as the cathode.
Electrodeposition coating was performed by applying the voltage for a minute to form an electrodeposition coating resin film on the exposed copper portion.

Next, after pulling up the substrate, it was washed with running water for 1 minute.
The adhering electrodeposition paint solution that had not been electrodeposited was removed, and after draining and drying, the electrodeposition paint was cured by heating at 130° C. for 20 minutes using a hot air dryer.

After cooling the board, it was immersed in a 4% sodium hydroxide aqueous solution at 40°C for 2 minutes to remove the resist coating layer with the reverse pattern, and then immersed in a 40Be ferric chloride aqueous solution at 50°C for 5 minutes to remove circuit unnecessary parts. The copper layer was dissolved and removed.

Next, after washing with water and draining, the electrodeposited resin film was immersed for 5 minutes in a release solution at 50°C consisting of 90 parts by weight of a 5% aqueous sodium hydroxide solution and 10 parts by weight of diethylene glycol monoethyl ether. , 1) Remove, wash and dry,
A through-hole printed wiring board was obtained that was electrically connected by a copper clad layer and a copper plating layer.

This through-hole printed wiring board had 1) no corrosion such as pinholes on the layer surface, and a fine pattern was formed with high precision.

Comparative Example 1 Electrodeposition-reverse pattern peeling-esoting-electrodeposition coating resin film peeling treatment was carried out in the same manner as in Example 1 except that the 3 liquids (electrodeposition paint) were not allowed to flow, to obtain a through-hole printed 'lfA board.

In this through-hole printed wiring board, many pinhole-like corrosion was observed on the surface of the copper layer at the through-hole land area, and between patterns with a line width of 100 μm, an electrodeposition paint resin film was formed on the resist coating layer of the opposite pattern. A short circuit was observed due to the overlapping of the etching processes, which prevented normal etching processing.

Comparative Example 2 A through-hole printed wiring board was obtained by carrying out the electrodeposition-reverse pattern peeling-etching-electrodeposition resin film peeling process in the same manner as in Example 1, except that the flow rate of the electrodeposition paint solution was adjusted to 60 cm/sec. Ta.

This through-hole printed wiring board has a v! ,
The copper layer in these areas was corroded due to insufficient thickness.

Comparative Example 3 A through-hole printed wiring board was obtained by carrying out the electrodeposition-reverse pattern peeling-esoting-electrodeposition coating resin film peeling process in the same manner as in Example 1, except that the flow rate of the electrodeposition paint solution was adjusted to 100 cm/sec. .

In this through-hole printed wiring board, no pinholes were observed on the surface of the copper layer, but because the formed electrodeposition paint resin film was extremely thin in some parts, the adhesion was poor when the reverse pattern resist coating layer was peeled off. Disconnection was observed due to part of the electrodeposited resin film peeling off due to lack of.

〔Effect of the invention〕

According to the method for manufacturing a through-hole printed wiring board of the present invention,
Because the electrodeposition coating resin film can be formed precisely at the specified location,
A high-performance through-hole plated wiring board can be manufactured with virtually no product defects.

[Brief explanation of the drawing]

FIG. 1 is a flow sheet showing an outline of the apparatus used for carrying out electrodeposition coating in the method for manufacturing a through-hole printed wiring board of the present invention, together with embodiments of the present invention. 1.Electrodeposition paint bathtub 2..Overflow tank 3..
Pump 4...Pipe E...Electrodeposition paint solution

Claims (3)

[Claims] (1) When forming an electrocoated resin film in the desired pattern by electrocoating on a double-sided copper-clad board that is electrically conductive through the copper plating layer of the through hole, the electrocoat solution is applied at a flow rate on the surface to be coated. 1. A method for manufacturing a through-hole printed wiring board, characterized by flowing the through-hole printed wiring board at a rate of 0.1 to 50 cm/sec. (2) The method for manufacturing a through-hole printed wiring board according to claim (1), wherein the flow rate is 0.5 to 20 cm/sec. (3) The method for manufacturing a through-hole printed wiring board according to claim (1), wherein the substrate has a resist coating layer formed in a reverse pattern on its surface.