JPS60166262A - Surface activation treatment of alumina ceramics - Google Patents

Abstract

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

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical field to which the invention pertains) The present invention relates to a surface activation treatment method for alumina ceramics.

(Technical background of the invention and its problems) Modern industrial materials are required to have various functionalities, and in the field of ceramics, the surface of ceramics is activated to improve printability and adhesion, and metal layers and glass compositions are directly attached. There is a strong demand for a method for strongly adhering.

Many methods have been invented, such as US Pat. No. 667.424 and US Pat. No. 3,180,756. Examples of such methods include a simultaneous firing method, a thick film printing and firing method, and a direct metal plating method. The simultaneous firing method is disclosed in Japanese Patent Application Laid-open No. 54-4945.
As shown in Publication No. 3, this is a method in which a metal paste is printed on an unfired sheet and the sheet and the metal paste are fired simultaneously.

Adhesion strength reaches the cohesive failure strength of ceramics, approximately 10
-12 Kpf/2, but because the process is complicated, the scope of application is limited, and it is expensive, it is applied to fields that require high reliability. The thick film printing and firing method, in which glass paste containing metal powder is printed and baked on the surface of ceramics, has poor heat resistance due to the presence of glass, and has problems with reliability of heat conduction, adhesive strength, etc. Therefore, as another method for simplifying the process and obtaining high thermal conductivity, a direct plating method disclosed in Japanese Patent Application Laid-open No. 79842/1984 has been considered. In this method, the surface of sintered ceramics is etched to make it rough, or the surface of the sintered ceramic is subjected to plating cedar treatment to impart plating activity to the surface of the ceramic, and then directly plated. There are problems such as low adhesive strength and poor reliability.

Generally, on the surface of high alumina ceramics, α-alumina particles are exposed, and the grain boundaries are filled with glassy and secondary crystal phases. Therefore, the surface after firing is smooth, and even if Shimetuki Seeder is applied, it hardly adheres to the surface of the alumina ceramics, so almost no plating is deposited. For this reason, it has conventionally been done to roughen the surface using hydrofluoric acid, etc., but the roughened surface etched by this method is simply the glass layer at the grain boundaries or the glass layer at the grain boundaries and the second crystal. α−
Etching of the alumina particles does not occur, and the roughened surface is extremely coarse, resulting in the formation of a coarsely uneven surface due to shedding of the α-alumina particles. Therefore, the plating seeder adheres to the coarse irregularities of these α-alumina particles, but the adhesive force after plating is small. Another roughening method is a method for roughening the surface of alumina ceramics by alkali melting treatment using sodium hydroxide or the like. In this method, sodium hydroxide is heated to a temperature higher than its melting temperature to form a molten liquid, and alumina ceramics are immersed in the molten liquid for etching, followed by washing with water to obtain a clean roughened surface. In this method, surface roughening progresses as alumina, glass, second crystal phase, etc. in the surface layer of alumina ceramics become molten salts and are eluted into the molten liquid. For this reason, on the alumina ceramic surface, elution of alumina and glass or alumina, glass and the second crystalline phase by etching and roughening proceed simultaneously, resulting in a relatively dense roughened surface. However, since the surface only has a simple roughened surface, it is difficult to obtain a sufficiently active surface. Therefore, plating activation treatment is performed with baladium, etc., and the plating metal is deposited by electroless plating. However, the adhesive strength of the plated metal layer is usually only about 0.5 to 1.5 Kff/mm2.

(Purpose of the invention) The object of the present invention is to eliminate the drawbacks of the prior art mentioned above.

The present invention provides a surface activation treatment method for alumina ceramics for firmly adhering metal layers and glass compositions.

(Means for Solving the Problems) The present inventors conducted various studies regarding the above-mentioned drawbacks, and found that
After paying attention to the fact that the second crystalline phase of alumina ceramics is fine grained and has a very large specific surface area, making it suitable for uniform treatment with plating seeders, the surface of alumina ceramics was roughened by etching.

By forming a second crystalline phase of the alumina ceramics on the roughened surface, it was possible to firmly adhere the metal layer and the glass composition to the alumina ceramics.

(Structure of the Invention) The present invention relates to a surface activation treatment method for alumina ceramics, which comprises the steps of etching and roughening the surface of alumina ceramics and forming a second crystalline phase of alumina ceramics on the roughened surface. .

The second crystalline phase of the alumina ceramics of the present invention is generally anorthite (CaO・Al2O5・2SiO
z)+Calcium hexaluminate (
CaO@6AI! z03).

Gehlenite (2Ca O・Al＊Os ・5
in2), Mullite (3A/20g ・28i
0z), 5pinel (MgO・AI!203), etc. In the present invention, these are collectively referred to as the first crystal phase.

In the present invention, as a method for etching and roughening the surface of alumina ceramics, a surface roughening method in which the surface is boiled in an alkaline aqueous solution of sodium hydroxide, potassium hydroxide, sodium orthosilicate, etc. is preferred. By firing after surface roughening, a second crystal phase is formed on the surface.

(Example) The present invention will be explained below with reference to Examples.

Hydroxide l-I in a nickel crucible with a capacity of 31,200 ml.
100ml of Jum 50chi aqueous solution! and heated to 95±5°C. Then add 40X40X thickness 1. Alumina ceramics with a purity of 96 cm, which had been molded to the size of an O-shaped body, was placed and gently boiled for 10 minutes. After that, the alumina ceramics were placed on top of the alumina refractory and fired. The firing conditions were that the temperature was raised to 500°C over 1 hour, held at 500°C for 1 hour, and then cooled.

After cooling, the surface was washed with water and then dried.

Next, the surface of this alumina ceramic was subjected to sensitization treatment and activation treatment by conventionally known methods, and then N1 plating was applied. After that, heat treatment was performed, soldering was performed, and adhesive strength was measured. Adhesive strength is 4.0-5.0 Kg f7
It was m2.

(Comparative Example) On the other hand, sodium hydroxide was placed in a nickel crucible and heated with a burner to melt the sodium hydroxide, and then an alumina ceramic having the same dimensions as above was placed in the crucible and alkali melting was performed. Next, after sensitization treatment and activation treatment, Ni plating was applied and the adhesive strength was measured, and it was 0.5~L
It was ON9 f /nun2. In the method of the present invention, α-
The extremely thin glass layer on the alumina surface is etched,
During heating and holding at 500°C, a second crystalline phase of alumina ceramics is formed and firmly adheres to the roughened surface, making it complicated.

It also forms a densely roughened surface, which facilitates the adhesion of plating seeders and is thought to serve as a plating anchor. On the other hand, alkaline melting alone roughens the surface of alumina ceramics, but since only a simple rough surface is formed, the anchoring effect of plating is not expressed and the adhesive strength is considered to be low.

Also, the adhesive strength of conventional methods is low.

In the conventional etching method, the surface is etched and unevenness is formed, but the plating seeder still adheres.

This is thought to be due to the plating coming off from the irregularities during the tensile test.

The reason why the excellent results of the present invention were obtained is that the second crystalline phase of the alumina ceramics is generated during firing of the alumina ceramics and is strongly bonded to the α-alumina particles in the monosilicon, and that the surface of the alumina ceramics is etched. This is because the second crystalline phase of the alumina ceramic, which adhered densely and firmly to the surface of the α-alumina activated by etching, contributed as an anchor effect in the adhesion direction. .

(Effects of the Invention) The present invention performs surface activation treatment on alumina ceramics through a process of etching and roughening the surface of alumina ceramics and a process of forming a second crystalline phase of alumina ceramics on this roughened surface. This allows the metal layer or glass composition to be firmly bonded to the alumina ceramics.

Continued from page 1 0 Inventor Mamoru Ueyama @ Inventor Yama 1) Takao Hitachi Chemical Co., Ltd. 4-1 Higashimachi, Hitachi City, Hitachi Chemical Co., Ltd., Ibaraki Laboratory, 4-1 Higashimachi, Hitachi City Inside Ibaraki Research Institute

Claims (1)

[Claims] 1. A surface activation treatment method for alumina ceramics, which comprises the steps of etching and roughening the surface of alumina ceramics and forming a second crystalline phase of alumina ceramics on this roughened surface.