JPH02174188A - Manufacture of ceramic wiring board - Google Patents

Abstract

PURPOSE:To prevent a warp of a board and oxidation of a metal film by applying heat treatment to a ceramic board having a polished surface so as to precipitate a glassy component to the surface followed by roughening the surface further plating the roughened surface for forming the metal film. CONSTITUTION:After precipitating a glassy component on the surface of a ceramic board by heat treatment of the ceramic board having the polished surface, the surface of the ceramic substrate is roughened, and further the roughened surface is plated to form a conductive metal film. Next, a pattern is formed by an etching method and a nickel layer is formed on the upper face of the pattern, and further on the upper surface thereof a noble metal layer is formed. Thereby, no warp of the board is generated while obtaining a good roughened surface so as to prevent a metal closely adhered to the surface from oxidizing.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a method of manufacturing a ceramic wiring board.

(Prior art) Conventional methods for adhering a metal coating, a glass composition, etc. to the surface of a ceramic substrate include forming a metal coating on an unfired ceramic substrate (ceramic green sheet) and firing the same at the same time. There is a firing method, and a thick film printing and firing method in which a mixed paste of glass powder and metal powder is printed on a fired ceramic substrate and then baked.

(Problem to be solved by the invention) However, the simultaneous firing method
Since the firing is performed at a temperature of 0 to 1600°C, the work is complicated and the cost is high. - The thick film printing and firing method is
The adhesion between the metal and ceramic substrate is done through glass, so the adhesion is weak.

Furthermore, since noble metals such as gold, silver, and palladium are used as metals, there is a drawback that the cost is high.

As an improvement of these, Japanese Patent Application Laid-Open No. 47-11652 8%
Publication No. 54-82666 8% Publication No. 58-10407
There is a method shown in Publication No. 9, etc. These methods treat sintered ceramics such as alumina with acids such as hydrofluoric acid and sodium hydroxide.

After being roughened by immersion in an alkaline solution, the surface of the ceramic is sensitized, then an activation treatment is performed, and copper plating, nickel plating, etc. are applied to adhere metal onto the ceramic.

However, the above method has problems with the material of the substrate used.9 For example, ceramic substrates whose surfaces are not polished may have a large degree of warpage, and ceramic substrates whose surfaces have been polished may not have good roughness. There is a problem that a surface cannot be obtained and metals such as copper and nickel that are brought into close contact with one surface are easily oxidized and cannot be used for ceramic wiring boards.

The object of the present invention is to provide a method for manufacturing a ceramic wiring board that does not have the above-mentioned drawbacks.

(Means for Solving the Problems) The present invention heat-treats a ceramic substrate whose surface has been polished to precipitate a glassy component on the surface of the ceramic substrate, then roughens the surface of the ceramic substrate, and further applies the roughened surface to the surface. The present invention relates to a method of manufacturing a ceramic wiring board, in which a metal film is formed by plating, a pattern is formed by etching, a nickel layer is formed on the top surface of the pattern, and a noble metal layer is formed on the top surface of the nickel layer.

The ceramic substrate used in the present invention is not particularly limited, but it is preferable to use an alumina ceramic substrate.

There are no particular restrictions on the method of polishing the surface of the ceramic substrate, and any conventionally known method may be used.

The heat treatment is preferably performed in the atmosphere, and the treatment temperature is appropriately selected depending on the material composition of the ceramic substrate.
Preferably it is carried out at a temperature of 0°C.

There are no particular restrictions on the method for roughening the surface of the ceramic substrate; any conventionally known method may be used.

Although there are no particular restrictions on the plating method, it is preferable to use electroless plating. There are no particular restrictions on the metal formed by plating as long as it has conductivity, but
It is preferable to use copper because it is inexpensive.

A noble metal such as gold, silver, or platinum is used for the noble metal layer formed as the outermost layer.

(Example) The present invention will be explained in detail below.

Example 1 Dimensions are 270 x 20 +++ m, thickness is 1.2 vtts
The surface of an alumina ceramic substrate (manufactured by Hitachi Chemical Co., Ltd., trade name: Halox 552) with a purity of 96% was polished using a polishing machine to a thickness of 0.9 wn, and after drying, it was placed in an electric furnace and heated at 1200°C. The temperature was raised at a rate of 5°C/min until
After being held at 1200° C. for 1 hour, it was cooled to obtain a ceramic substrate on which glassy components were precipitated.

Next, the ceramic substrate obtained above was washed with a degreasing solution (Hitachi Chemical Membrane, trade name: HCR201), and after drying, NH4F
10 g (40.5 weight i%), (NHi)tsO
4Ig (4.1% by weight), m H2SO42ml
(14,9% by weight) and Hzo 10ml (40,5
Roughening was performed by immersing the sample in a mixed solution (liquid temperature: 50° C.) of 50° C. (weight f%) for 5 minutes. Then, rinse thoroughly under running water and dry.
Re-roughening was performed by immersing it in a NaOH melt heated to 50° C. for 5 minutes. After that, 5
The ceramic surface was immersed for 3 minutes, and vibration energy was applied using ultrasonic waves (output 300 W) to neutralize the ceramic surface, followed by washing with water and electroless steel plating for 3 hours to form a steel film with a thickness of 7 μm. The electroless plating solution used had a pH of 12.4 and a composition shown in Table 1.

Table 1: After plating, a photosensitive dry film (Hitachi Chemical Membrane, trade name PHT-862F-40) was used.

Etch both sides of the board with cupric chloride solution to size 2x2.
A m+m pattern was formed, and electroless nickel plating (Nippon Kanizenkyu, trade name S-680) was performed on the top surface of the pattern for 10 minutes to form a nickel film with a thickness of 3 μm.
Furthermore, electroless gold plating (Left Roless Blebbing, manufactured by EEJA) was performed on the upper surface for 20 minutes to form a gold film with a thickness of 0.2 μm.

Next KW gas 1 Solder resist (manufactured by Asahi Chemical Research Institute, trade name Ca-aooLL) is applied to the parts that require mechanical protection.
) was printed and cured at 180° C. for 30 minutes to obtain a ceramic wiring board.

The adhesion (adhesion) strength was measured using 20 of the obtained ceramic wiring boards. As a result, the average was 25kg/lan.”
It showed an adhesion strength of . Further, ultrasonic cleaning was performed for 30 minutes, but the pattern was not peeled off and the result was good. Furthermore, the appearance was observed, and there was no warping of the substrate, and the surface roughness of the substrate was 3.0 to 4.0 μm (P-P), which was a good value.

Comparative Example 1 A ceramic wiring board was obtained through the same steps as in Example 1 except that the heat treatment step in Example 1 was omitted.

Adhesion strength was measured using 20 of the obtained ceramic wiring boards. As a result, the average weight was as low as 1.5 kg/rrrm2.When ultrasonic cleaning was performed, the conductor circuit peeled off in 10 minutes. When we observed the appearance, we found that the substrate was slightly warped, and the surface roughness of the substrate was 6.0 to 8.0 μm (P-
P) and the roughness was twice that of Example 1.

Comparative Example 2 A ceramic wiring board was obtained through the same steps as in Example 1, except that the surface polishing and heat treatment steps in Example 1 were omitted.

Adhesion strength was measured using 20 of the obtained ceramic wiring boards. The results showed an average adhesion strength of 2.5 kg/wn2, the pattern did not peel off even after 30 minutes of ultrasonic cleaning, and the surface roughness of the substrate was 3.
．． Although it showed a good value of 0 to 4.0 μm (P-P), large warpage occurred in the substrate.

(Effect of the invention) According to the present invention, no warping occurs on the ceramic substrate.

A strong metal coating can be formed using the plating method.

A ceramic wiring board whose metal coating is prevented from oxidation can be obtained.

Agent Patent Attorney Kunihiko Wakabayashi

Claims (1)

[Claims] 1. After heat-treating the ceramic substrate with a polished surface to deposit a glassy component on the surface of the ceramic substrate, the surface of the ceramic substrate is roughened, and the roughened surface is further plated to form a metal coating. A method of manufacturing a ceramic wiring board characterized by forming a pattern using an etching method, forming a nickel layer on the top surface of the pattern, and then forming a noble metal layer on the top surface of the nickel layer.