JPS5816626B2 - Method for manufacturing multilayer printed wiring board - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a multilayer printed wiring board.

Multilayer printed wiring boards have conventionally been manufactured in the following manner.

In other words, a copper-clad laminate for the inner layer is made by processing the copper foil of a normal copper-clad laminate and forming printed wiring.
This copper foil is treated with chemicals such as ammonium persulfate, cupric chloride, and copper acetate to improve adhesion and chemical resistance.

Next, this was washed with water to remove the chemicals, and then heated and dried to dry the moisture, and the copper-clad laminate for the outer layer was applied to this copper-clad laminate for the inner layer via a thermosetting resin-impregnated base material (prepreg). It was manufactured by laminating and bonding.

However, this method uses heating and drying to remove moisture.
Because the treated copper foil surface oxidizes and causes rust etc. and discoloration,
The multilayer printed wiring board has drawbacks such as variations in adhesive strength, deterioration in chemical resistance, and color unevenness.

In addition, multilayer printed wiring boards can also be produced by using copper-clad laminates for inner layers, in which printed wiring is formed by pasting copper foil whose surface has been roughened to improve adhesion (double-sided roughened copper foil) to the laminate. It was manufactured.

According to this method, the chemical treatment step of the above-mentioned method can be omitted.

However, in order to prevent variations in adhesive strength due to rust on the roughened copper foil surface, deterioration of the chemical resistance of the rusted surface, and occurrence of color unevenness, the roughened copper foil is treated with a chemical such as acid to remove rust. It was then washed with water to remove the acid and then heated and dried.

However, even with this method, rust was generated secondary to heating in the drying process after washing with water.

In order to avoid this, a method has been proposed in which the copper-clad laminate for the inner layer is immediately immersed in an organic solvent after washing with water, the moisture is removed by replacing it with the organic solvent, and then the laminate is heated and dried.

However, even this method was not sufficient and some degree of rusting was unavoidable.

Therefore, the purpose of this invention is to reduce the variation in adhesive strength.
An object of the present invention is to provide a method for manufacturing a multilayer printed wiring board that does not cause deterioration in chemical resistance or color unevenness.

The feature of this invention is that the metal foil of the metal foil-clad laminate for the inner layer is chemically treated with a chemical to improve its adhesion and chemical resistance, then washed with water to remove the chemical, and then treated with a solvent containing resin. At the same time, a thin film of resin is formed on the metal foil, the metal foil is dried, and the inner layer metal foil-clad laminate is coated with a thermosetting resin-impregnated base material. The purpose is to laminate and bond metal foil-clad laminates for the outer layer.

That is, in this invention, since a thin resin film is formed on the metal foil, air and the metal foil are blocked during the drying process, so that oxidation does not occur.

Therefore, variations in adhesive strength, deterioration in chemical resistance, and color unevenness of the multilayer printed wiring board caused by rusting due to oxidation of the metal foil are prevented.

Next, this invention will be explained in detail.

In this invention, a copper-clad laminate for the inner layer using a normal metal foil, for example, copper foil, is chemically treated with a chemical such as ammonium persulfate, or After the clad laminate is chemically treated with chemicals such as acids, it is immediately thoroughly washed with water to remove those chemicals, and the copper foil of the copper clad laminate for the inner layer is treated with a solvent to remove moisture.

This solvent treatment for removing water can be carried out, for example, by immersing the copper-clad laminate for the inner layer in an organic solvent to replace the water adhering to the surface of the laminate with the organic solvent.

Then, the copper foil of the inner layer copper-clad laminate, which has been treated with a solvent to remove moisture, is treated with a solvent in which resin is dissolved to form a resin thin film on the surface of the copper foil.

This resin thin film forming treatment can be carried out, for example, by immersing the copper-clad laminate for the inner layer from which water has been removed into an organic solvent in which a resin is dissolved.

Further, the water removal solvent treatment and the resin thin film forming treatment may be performed simultaneously.

In other words, by dissolving the resin in a solvent for moisture removal and treating the copper-clad laminate for the inner layer with it, moisture removal and resin thin film formation may be performed at the same time.)
.

Next, the copper-clad laminate for inner layer on which the resin thin film is formed is dried, for example, by heating.

In this case, the copper foil is covered with a thin resin film and is isolated from the air, so it is not oxidized.

Therefore, the occurrence of harmful effects due to rusting can be avoided.

As the resin used for forming the resin thin film, any resin may be used as long as it has the ability to form a thin film, but it is preferable to use a thermosetting resin.

When such a resin is used, a thermosetting resin thin film is formed on the surface of the copper foil, and this is cured in a heat drying process.

As a result, the adhesiveness of the resin thin film is lost, making subsequent work easier.

In addition, since the surface of the copper foil does not come in direct contact with fingers, there is no rust caused by fingerprints, and it is less susceptible to scratches.

Next, a metal foil-clad laminate for the outer layer, such as a copper-clad laminate, is laminated and bonded in a conventional manner to the copper-clad laminate for the inner layer on which the resin thin film has been formed via the prepreg, thereby performing multilayer printing. A wiring board is obtained.

The thus obtained multilayer Print 1 wiring board does not suffer from variations in adhesive strength, deterioration in chemical resistance, and color unevenness.

Next, examples will be described.

Example 1 Double-sided roughened copper foil (thickness) 70 μm with double-print wiring formed
) clad laminate (copper clad laminate for inner layer) in dilute hydrochloric acid (water:hydrochloric acid=
10:1) for 30 seconds to remove rust, rinsed with running water three times, and then drained.

Next, it was immersed in methyl ethyl ketone for 10 seconds, and again in methyl ethyl ketone for 10 seconds.

Next, this was added to a resin thin film forming treatment solution with the following composition.
After being immersed for 0 seconds, it was dried at 120° C. for 60 minutes.

Methyl ethyl ketone mixed with resin thin film forming treatment liquid = 100 parts by weight; Epoxy resin (trade name: Epicoat 827, manufactured by Shell Co., Ltd.)
= 10 parts by weight Curing agent (product name: NI61B1 manufactured by Sale Chilney): 1 part by weight The copper-clad laminate for the inner layer treated in this way does not cause rust,
No uneven color was observed.

Next, a copper-clad laminate for an outer layer was laminated and molded on this laminate in a conventional manner via a prepreg to obtain a multilayer printed wiring board.

Conventional Example 1: The steel clad laminate for the inner layer of Example 1 was treated with dilute hydrochloric acid in the same manner as in Example 1, then washed with running water, and immediately heated and dried.

Using the thus treated copper-clad laminate for inner layers, a multilayer printed wiring board was obtained in the same manner as in Example 1.

Conventional Example 2: The copper-clad laminate for the inner layer of Example 1 was treated with dilute hydrochloric acid in the same manner as in Example 1, then washed with running water three times, and then drained.

Next, it was immersed in methyl ethyl ketone for 10 seconds, immersed again in methyl ethyl ketone for 10 seconds, and then immediately heated and dried.

Using the thus treated copper-clad laminate for inner layers, a multilayer printed wiring board was obtained in the same manner as in Example 1.

Example 2 A copper clad laminate for the inner layer was prepared by treating the copper foil of a normal copper clad laminate with double-print wiring in accordance with a normal method with copper acetate, and after washing it with water, it was immediately immersed in methyl ethyl ketone for 10 seconds. Then, it was immersed again in methyl ethyl ketone for 10 seconds.

Next, this was immersed for 10 seconds in the same resin thin film forming treatment solution as in Example 1, and then dried at 120° C. for 60 minutes.

Copper-clad laminates for inner layers treated in this way will cause rust and
No uneven color was observed.

Next, a copper-clad laminate for an outer layer was laminated and molded on this laminate with a prepreg interposed therebetween in a conventional manner to obtain a multilayer printed wiring board.

Conventional Example 3 A copper clad laminate for an inner layer was prepared by treating the copper foil of a normal copper clad laminate with double-printed wiring according to a conventional method with copper acetate, and after washing with water, it was immediately heated and dried.

Using the thus treated copper-clad laminate for inner layers, a multilayer printed wiring board was obtained in the same manner as in Example 1.

The results of the performance tests of the multilayer printed wiring boards obtained in the above examples and conventional examples are shown in the following table.

Claims (1)

[Claims] 1. The metal foil of the metal foil-clad laminate for the inner layer is chemically treated with a chemical to improve its adhesion and chemical resistance, then washed with water to remove the chemical, and then treated with a solvent containing resin. At the same time, a thin film of resin is formed on the metal foil, the metal foil is dried, and the inner layer metal foil-clad laminate is coated with a thermosetting resin-impregnated base material. A method for producing a multilayer printed wiring board in which a metal foil-clad laminate for the outer layer is laminated and bonded. 2. The method according to claim 1, wherein the resin is a thermosetting resin, and the drying is heat drying, and the heat drying hardens the thin film of the thermosetting resin on the metal foil. A method for manufacturing a multilayer printed wiring board.