JPH05235508A - Manufacture of ceramic wiring board - Google Patents

Abstract

PURPOSE:To prevent the dropping-out of nuclear, and easily form a metal film having high adhesion on the surface of a ceramic substrate without skip phenomenon. CONSTITUTION:In a manufacturing method of a ceramic wiring board which method contains a process wherein, after a nucleation process is performed on the surface of a ceramic substrate, a metal film is formed by using electroless plating, heat treatment is performed after the nucleation process is performed, and the electroless plating is performed. Thus a ceramic wiring board is manufactured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a ceramic wiring board.

[0002]

2. Description of the Related Art One of the methods for manufacturing a ceramic wiring board using electroless plating is the full additive method. In this case, after depositing (nucleating) nuclei for electroless plating (for example, Pd nuclei) on the surface of the ceramic substrate, a resist mask is formed and then covered with a resist layer on the surface of the ceramic substrate. A metal film (conductor layer) is deposited by electroless plating on the unetched portion.

The above method has an advantage that the cost can be reduced, but has a problem that the core for electroless plating is easily dropped. The detachment of the nuclei causes a skip phenomenon (a phenomenon in which the metal film is not partially deposited) in the electroless plating or a decrease in adhesion of the metal film to the ceramic substrate. The reason why the nuclei fall off easily occurs because the nuclei are physically adsorbed on the surface of the ceramic substrate, but the problem of the nuclei fall off is particularly remarkable in the following cases.

When a photosensitive organic resist material is used for forming the resist mask, there is an advantage that a fine circuit can be formed with high accuracy. Normally, a resist mask is completed by applying a photosensitive organic resist material, then exposing and developing it, but it is necessary to carry out a cleaning process to remove unnecessary resist materials, and this cleaning process causes the nucleus to fall off easily. ..
In particular, when the circuit is fine, a slight skip phenomenon and a decrease in the adhesion of the metal film lead to a defective circuit, so it is necessary to reliably prevent the core from falling off.

[0005]

SUMMARY OF THE INVENTION In view of the above circumstances, the present invention is capable of easily forming a metal film on the surface of a ceramic substrate, which prevents the nucleus from falling off, has no skip phenomenon, and has high adhesion. An object is to provide a method for manufacturing a ceramic wiring board.

[0006]

In view of the above circumstances, the present invention provides a method for manufacturing a ceramic wiring board according to the present invention, in which a surface of a ceramic substrate is subjected to a nucleating treatment and then a metal film is formed by electroless plating. In the step of performing, the electroless plating is performed after the heat treatment after the nucleation treatment.

The ceramic substrate used in the present invention does not have to be a specific one, and various known ceramic substrates such as an alumina substrate can be used. However, it is preferable that the surface of the ceramic substrate is roughened.
This is because by roughening the surface, the metal film formed by electroless plating is mechanically bonded to the surface of the substrate and high adhesion can be obtained. The method of surface roughening is not particularly limited.

In the case of the present invention, first, the surface of the ceramic substrate is subjected to a nucleating treatment. The nucleation treatment method does not have to be a specific method, and known sensitizer-activator method, catalyst-accelerator method and the like can be mentioned. After the nucleation process, the ceramic substrate is heat treated. This heat treatment is preferably performed in an inert atmosphere such as a nitrogen atmosphere or in a vacuum atmosphere.
Otherwise, for example, Pd nuclei may be oxidized to lose the function as nuclei. However, if the function as the core is not impaired, it is not necessary to perform the heat treatment in a specific atmosphere. When heat treatment is performed, the nucleated ceramic substrate is held at a temperature of about 500 to 900 ° C. for about 5 to 30 minutes. By this heat treatment, nuclei (for example, Pd) attached to the surface of the ceramic substrate are
The nucleus will be fixed.

Subsequently, a resist mask is formed on the surface of the ceramic substrate. This resist mask is preferably formed using a photosensitive organic resist material (photosensitive organic resin composition or the like). A photosensitive organic resist material is applied to the surface of the ceramic substrate, and then exposed and developed to form a resist mask having a predetermined pattern. Of course, the resist material for forming the resist mask is not limited to the photosensitive organic resist material, and a resist material (for example, a thermosetting resist material) capable of forming a mask without a cleaning process may be used. Good.

The resist mask may be removed after electroless plating or may be a permanent resist mask without being removed. Finally, electroless plating is performed to deposit and form a metal film on the surface of the ceramic substrate where there is no resist layer. It is preferable to activate the nucleus with an acid before the electroless plating treatment. As electroless plating, various ones such as electroless copper plating and electroless nickel plating can be used and are not limited to particular ones.

In the above description, the ceramic wiring board is obtained according to the so-called full-additive method. However, the present invention does not necessarily follow the full-additive method, and may follow the semi-additive method, for example. ..

[0012]

In the method of manufacturing a ceramic wiring board according to the present invention, since the nuclei are fixed on the surface of the ceramic substrate by the heat treatment performed after the nucleation process, the cleaning process is performed in the resist mask formation. Even in
It is difficult for the nucleus to fall off, and the deposited metal film does not show a skip phenomenon or a decrease in adhesion. Besides, since only a very simple operation of heat treatment is added to the conventional process for preventing the detachment of the nuclei, the above-mentioned appropriate metal film can be easily formed on the surface of the ceramic substrate.

Usually, a resist mask is formed before electroless plating. However, when the resist mask is formed using a photosensitive organic resist material, a resist mask having a fine pattern can be formed, and as a result, a fine circuit can be formed. The additional advantage is that the ceramic wiring board can be manufactured.

[0014]

Embodiments of the present invention will be described in detail below.
The present invention is not limited to the following embodiments. -Example 1-As a ceramic substrate, a commercially available 96% alumina substrate (length 10 cm, width 10 cm, thickness 0.5 mm) was used, and this was immersed in a hot phosphoric acid bath at 330 ° C for 3 minutes for roughening treatment. .

After the roughening, a sensitizer-activator method was used to carry out a nucleation treatment for adhering Pd nuclei, which are nuclei for electroless plating, to the surface of the ceramic substrate. Then, the ceramic substrate subjected to the nucleation treatment was placed in a nitrogen atmosphere,
Heat treatment was performed at a temperature of 800 ° C. for 15 minutes. Then, a photosensitive solder resist material (photosensitive organic resist material) was applied on the surface of the ceramic substrate, and then exposed and developed to form a resist mask having a predetermined pattern on the surface of the substrate.

After activating the Pd nuclei with 5% hydrochloric acid, the ceramic substrate is dipped in a known high-speed electroless copper plating bath to deposit a copper film having a thickness of 10 μm on a portion without a resist layer. It was The resist mask was left without being removed. No skip phenomenon was observed in the copper film deposited on the surface of the ceramic substrate, and the adhesion of the copper film was sufficiently high at 2.5 kg / mm ² or more.

Example 2 A ceramic wiring board was obtained in the same manner as in Example 1 except that the heat treatment was performed in a nitrogen atmosphere at a temperature of 900 ° C. for 10 minutes, but the same as in Example 1. Results were obtained. -Example 3 Example 2 was repeated except that the resist mask was formed of a photosensitive plating resist material (photosensitive organic resist material) and the resist mask was removed after electroless plating.
A ceramic wiring board was obtained in the same manner as in, but the same results as in Example 2 were obtained.

Example 4 A ceramic is prepared in the same manner as in Example 1 except that the resist mask is formed by applying a thermosetting solder resist material on the surface of the ceramic substrate in a predetermined pattern and curing it. A wiring board was obtained, and the same results as in Example 1 were obtained. Example 5 A ceramic wiring board was obtained in the same manner as in Example 1 except that the heat treatment was performed in vacuum at a temperature of 600 ° C. for 20 minutes, but the same results as in Example 1 were obtained. It was

-Comparative Example 1-A ceramic wiring board was obtained in the same manner as in Example 1 except that the heat treatment was omitted. However, a skip phenomenon was observed in the copper film and the adhesion of the copper film was 0.5 kg / mm. ^It was very low, around 2. Comparing the results of Example 1 and Comparative Example 1, it can be clearly seen that the heat treatment performed after the nucleation treatment is very effective in preventing the nucleus from falling off.

[0020]

In the method for manufacturing a ceramic wiring board according to the present invention, since the nuclei are fixed on the surface of the ceramic substrate by the heat treatment, the nuclei do not fall off even when the cleaning process is performed in forming the resist mask. It is hard to occur, and not only the skip phenomenon and the decrease in adhesion force are not seen in the deposited metal film, but it is only a very simple operation called heat treatment that is added to the conventional process to prevent the nucleus from falling off, It is easy to form the appropriate metal film on the surface of the ceramic substrate, and the present invention is very useful.

Further, when the resist mask is formed on the surface of the ceramic substrate by using the photosensitive organic resist material, there is an additional advantage that a ceramic wiring board having a fine circuit can be manufactured.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masaya Koyama 1048 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Works Co., Ltd.

Claims (2)

[Claims] 1. A method for manufacturing a ceramic wiring board, comprising a step of forming a metal film by electroless plating after performing a nucleating treatment on the surface of a ceramic substrate, and performing a heat treatment after the nucleating treatment and then performing the electroless plating. A method for manufacturing a ceramic wiring board, which comprises performing plating. 2. The method for manufacturing a ceramic wiring board according to claim 1, wherein after the heat treatment, a resist mask is formed on the surface of the ceramic substrate using a photosensitive organic resist material, and then electroless plating is performed.