JPS59121176A - Ceramic metallization - 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 The present invention relates to a method of forming a metallized layer of metallic copper on a ceramic surface.

Ceramic is attracting attention as a new material that can replace metals due to its excellent heat resistance, wear resistance, and insulation properties. However, since ceramic is brittle and susceptible to impact, it is rarely used alone as a structural material, and when actually used, it is usually used in conjunction with metal.

To join metal and ceramic, it is first necessary to metalize the ceramic surface.

Conventionally, there are many techniques for forming a metal layer on a ceramic surface, such as the Telefunken method, the active metal method, the hydride method, the metal oxide method, and the silver carbonate method.

These methods involve complicated steps and often involve heat treatment in vacuum or in a non-oxidizing atmosphere.

In Japanese Patent Publication No. 47-2°1569, a paste made by mixing CuS powder and kaolin powder is applied to ceramic, heated in air at a temperature of 1200 to 1300°C, and then taken out and reheated at about 800°C while carbonated. This is a method of dispersing silver.

This method provides strong adhesive strength, but requires a total of two heating steps to create the silver coating. Furthermore, since it uses silver, it is disadvantageous in terms of cost, and it is difficult to actually use it. JP-A No. 53-130714 also
It is similar in that silver is used. Further, in the high melting point metal method, the baking temperature is 1400° C. or higher, the atmosphere is non-oxidizing, and an expensive atmosphere furnace is required.

The present invention was achieved as a result of intensive research focused on these difficulties and with the aim of forming a metallized layer on the ceramic surface that has even stronger adhesion and good conductivity.

In the present invention, copper sulfide or a mixture containing copper sulfide and kaolin is uniformly applied to the surface of a ceramic, and a heat reaction is performed at a temperature of 900°C or higher in the air or a nitrogen-containing atmosphere to form a baked coating layer. This is a method of reducing the baked coating layer to provide a metallized layer of metallic copper on the surface of the ceramic.

In the method of the present invention, a metallized layer of metallic copper produced by reducing a three-component compound of AAzOa-8i 02-CLI baked at a temperature of 900° C. or higher provides a particularly favorable effect.

By heating above 900°C, copper sulfide decomposes into CU and S, and Cu, together with kaolin, AQzOa-8!
02-CLI becomes a 3-component compound with a relatively low melting point than kaolin itself or copper sulfide itself, and this compound penetrates into the ceramic and reacts with the ceramic, making it stronger than when it does not contain kaolin. Provides strong adhesion.

On the other hand, since S generated by the decomposition of copper sulfide has activity against ceramics, it is thought that it promotes the penetration of the three-component compound into the ceramic and completes the reaction.

In particular, if the temperature is 900°C or higher, the activity of S increases and the effect is great. When a copper compound other than copper sulfide is used, for example, cuprous oxide, the above-mentioned effect of S is not obtained, and the
Penetration and reaction of the three-component compound consisting of Oa-8iO2-Cu into the ceramic were insufficient, and the adhesive strength after reduction was weak.

As the reduction method, any method may be used as long as copper sulfide is reduced to metallic copper and conductivity is obtained, such as heating in a hydrogen atmosphere, heating in a -carbon oxide atmosphere, and reduction with hydrocarbons.

The mixing ratio of copper sulfide and kaolin is preferably 100 to 20% by weight for the former, and 0 to 80% by weight for the latter.If the amount of kaolin is greater or less than this, the adhesion and permeability of the intermediate layer will decrease. It's unpleasant and undesirable.

Furthermore, if the copper sulfide content is less than 20%', it is difficult to obtain sufficient conductivity after reduction.

The heating conditions in the paste baking process cannot be determined uniquely depending on the shape and size of the ceramic or the quality of the kaolin, but it is usually heated at a temperature of 900°C (rN L/1400°C for 3 to 30 minutes.900 The above reaction tends to decrease at temperatures below 900℃ from the point of view of reactivity.
The temperature is preferably 1,400°C or higher, and since the viscosity tends to decrease at temperatures exceeding 1,400°C, the temperature is preferably 1,400°C or lower from the viewpoint of forming an intermediate layer. The heating during reduction is preferably lower than the reaction temperature described above in order to prevent decomposition, alteration, etc. of the reaction layer. Further, when joining the metallized reramic and metal by a method such as brazing, it is preferable that the heating be lower than the reaction temperature.

As detailed above, the ceramic metallization method of the present invention provides good electrical conductivity by providing a baking layer containing copper sulfide or copper sulfide and kaolin on the surface of the ceramic, and then reducing the baking coating layer. It has become possible to form a metalized layer of copper on the ceramic surface that is large and has good bonding properties with metal.

Since the ceramic having a copper metallized layer on its surface produced by the present invention has the above-mentioned performance, it can be applied to electronic components such as ceramic packages, wear-resistant parts using ceramic, heat-resistant parts, etc. It is.

Next, examples of the present invention will be shown.

Example 90 parts by weight of copper sulfide and 10 parts by weight of kaolin were mixed, and balsam was added to the mixture to obtain a paste-like mixture. This mixture was formed into a square plate of 3 i 3 N a , Sialon,
A sintered body of SiC or AAzOa is coated with 0.0% by weight of the mixture.
An amount equivalent to 1o/αδ was applied.

Next, it was fired at 1200° C. in the air using an electric furnace to form a coating layer.

The fired product was heated to 300°C in a dryer and then immersed in a commercially available Elatool. As a result, the coating layer was reduced to form a metallized layer of metallic copper.

Table 1 shows the electrical resistance of the baked coating layer before and after reduction.

The thus obtained ceramic having the metallized layer was soldered to a copper piece using silver solder, and the weight was 111 tons.

When the adhesive strength was measured using a tensile tester with a loading speed of 5t5mm/min, it was S! 350k in aNa.

/-, 400 k for SiAlON (1/aA, 3 for SiC
50k (110 crystal, A 600 ka/- strength was obtained at zOa, and it was recognized that the bond was extremely strong.

Claims (1)

[Claims] 1. A method for metallizing ceramics, which comprises providing a baked coating layer containing copper sulfide or copper sulfide and phosphorus on a ceramic surface, and then reducing the baked coating layer.