JPS6410471B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to a simple method for metallizing ceramics. Conventional technology and its problems In general, ceramics have high heat resistance, wear resistance,
Although it has excellent insulation properties, it is brittle and susceptible to impact, so when used as a structural material, it is often used as a bonded product with metal. First, it is necessary to metalize the ceramic surface. Furthermore, when ceramics are used as a conductive material, the surface of the ceramics is metallized. Known methods for metallizing ceramics include the Telefunken method, the active metal method, the hydride method, the oxide solder method, and the silver carbonate method. Among these methods, methods other than the Telefunken method have complicated processes, as well as the adhesive strength of the metallized layer,
Since thermal shock resistance, chemical resistance, etc. may not be sufficient, the Telefunken method is generally used at present. In the Telefunken method, the ceramic surface is coated with molybdenum-manganese, baked at a high temperature of 1400 to 1700°C in a non-oxidizing atmosphere, plated with metal, and then coated again in a non-oxidizing atmosphere to stabilize the coating. The method involves metallizing by heating the metal, and then brazing the metals as necessary, which has major disadvantages in that the working process is long and complicated, and also in that the heating temperature is high. Means for Solving the Problems As a result of intensive research to develop a ceramic metallization method that eliminates the above-mentioned drawbacks, the present inventor found that when copper oxide or (and) copper sulfide is used as a coating layer, oxidation of air, etc. Baking can be carried out at a relatively low temperature in an atmosphere, and then the baked layer can be subjected to a reduction treatment, making it extremely easy to metallize (in addition,
A separate application has been filed regarding a method of using copper sulfide alone as a coating layer. ), we discovered that when metallic silver or (and) metallic copper is used in combination as a coating layer, the smoothness of the surface of the metallized layer improves, and that the obtained metallized layer has excellent conductivity and high adhesive strength. The invention was completed. That is, the present invention coats a ceramic surface with a mixture of copper oxide or (and) copper sulfide and metallic silver or (and) metallic copper, and heats the ceramic surface at 900 to 1300°C in an oxidizing atmosphere.
The present invention relates to a method for metallizing ceramics, which is characterized in that the baked layer is subjected to a reduction treatment after being heated and baked. The mixture of copper oxide and/or copper sulfide and metallic silver and/or metallic copper used as the coating layer in the present invention is usually in powder form. When using copper oxide and copper sulfide, the ratio of both may be arbitrary. In the present invention, the smoothness of the surface of the metallized layer can be improved by using copper oxide or (and) copper sulfide (hereinafter simply referred to as a copper compound) in combination with metallic silver or (and) metallic copper as a coating layer. . Metallic silver and/or metallic copper are usually used in powder form, and the proportion used is preferably about 80% of the total weight with the copper compound at the upper limit. If it exceeds 80% by weight, the adhesive strength of the metallized layer tends to decrease, which is not preferable. As the material for forming the coating layer in the present invention, a mixture of a copper compound and metallic silver and/or metallic copper may be used in powder form, or a suitable binder and its solvent, such as printing ink such as screen oil, may be used. It may be used in the form of a paste using an appropriate amount of balsam or the like. A mixture of a powdered or paste-like copper compound and metallic silver and/or metallic copper is sprinkled or applied onto the ceramic surface that requires metallization to coat it.
The amount of coating is not particularly limited, and is appropriately determined depending on the desired thickness of the metallized layer. Next, the ceramic coated above is heated in an oxidizing atmosphere to bake the coating layer. There is no need to use a special oxidizing atmosphere; air,
It is sufficient to use a mixture of air and nitrogen. The heating conditions vary depending on the shape and size of the ceramic, the type of coating layer used, the amount of coating, etc., but are usually 900 to 1300℃ and 5 to 60℃.
Heat for about a minute. By this heating, a coating containing copper oxide-silver oxide (copper sulfide, metallic copper is oxidized to become copper oxide, and metallic silver is oxidized to become silver oxide) adheres to the ceramic. On this occasion,
The copper oxide melt partially penetrates into the ceramics (when copper oxide is used, the sulfur generated when it is oxidized to copper oxide further promotes this penetration)
This increases the adhesive strength. heating temperature
If it is lower than 900°C, the above-mentioned penetration will not occur and the adhesive strength will be insufficient, and if it is higher than 1300°C, the viscosity of the coating layer will decrease and it may flow out, which is not preferable. Next, the ceramics on which the baked layer has been applied as described above is subjected to a reduction treatment. The reduction method is not particularly limited, and any method may be used as long as copper oxide and silver oxide are reduced to these metals, such as heating in a reducing atmosphere such as a hydrogen atmosphere or a carbon monoxide atmosphere, ethanol, Examples include immersion in alcohols such as methanol and propanol, and reducing solvents such as benzene and formalin. When heating in a reducing atmosphere, the temperature is preferably lower than the baking temperature to prevent decomposition, alteration, etc. of the baked layer, and is usually about 200 to 900°C, and the time is usually about 5 to 60 minutes. . In addition, when immersing ceramics in reducing solvents, ceramics are usually
After heating to about ~500°C, preferably around 300°C, it may be immersed in the above-mentioned reducing solvent for about 10 to 60 seconds. By the above reduction treatment, a copper-silver metallized layer having extremely excellent conductivity is formed on the ceramic surface. In the present invention, it is essential that a mixture of a copper compound and metallic silver and/or metallic copper be applied to the ceramic surface, then fired in an oxidizing atmosphere, and then subjected to a reduction treatment. If direct reduction treatment is performed without firing in an oxidizing atmosphere, the copper oxide melt will not penetrate deeply into the ceramics, so the adhesive strength between the metallized layer and the ceramics will be extremely low. It cannot be put to practical use. In this way, metallized ceramics have
If necessary, various metals can be easily joined by conventional methods such as brazing. Ceramics that can be metallized according to the present invention are not particularly limited, and include, for example, non-oxide ceramics such as silicon nitride, sialon, silicon carbide, and aluminum nitride, and oxide ceramics such as alumina, zirconia, mullite, beryllia, magnesia, and cordierite. can be mentioned. According to the present invention, a metallized layer can be formed on a ceramic surface by an extremely simple operation of baking at a lower temperature and then performing a reduction treatment compared to conventional methods. The obtained metallized layer has excellent conductivity and high adhesive strength, and the smoothness of the metallized layer is improved. Since the metallized ceramic according to the present invention has the above-mentioned performance, it can be suitably used for electronic parts such as ceramic packages, wear-resistant parts using ceramics, heat-resistant parts, etc. The method of the present invention can also be applied to metal plates such as nickel plates and copper plates, and a strong protective film can be obtained by reducing the coating layer. EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to Examples. Example 1 10 parts by weight of a mixture of 90% by weight copper oxide powder and 10% by weight metal silver powder was mixed with 10 parts by weight of balsam to obtain a paste-like mixture. This is made of flat square silicon nitride (Si ₃ N ₄ ), sialon,
0.1 g/cm ² was applied to the surface of a sintered body of silicon carbide (SiC), alumina, or zirconia. Next, it was baked in air at 1100° C. for 30 minutes using an electric furnace to form a baked coating layer. The calcined product was then heated to 300° C. in a dryer and then immersed in commercially available ethanol. As a result, the baked coating layer was reduced, and a metallized layer consisting of metallic copper and metallic silver was formed. Table 1 below shows 1000V before and after reduction.
The electrical resistance value measured at the voltage of It can be seen that the metallized layer after reduction has extremely excellent conductivity. Each ceramic having a metallized layer thus obtained and a copper piece were soldered using silver solder, and weighed.
The adhesive strength of the metallized layer was measured using a tensile tester with a load rate of 2 tons and a loading rate of 5 mm/min.
It was found that both were extremely strongly bonded. The results are also listed in Table 1 below.

[Table] In addition, the surface of the metallized layer has almost no unevenness,
It had excellent smoothness. Example 2 10 parts by weight of a mixture of 90% by weight of copper sulfide powder and 10% by weight of metallic silver powder was mixed with 10 parts by weight of balsam to obtain a paste-like mixture. Using this, a metallized layer was formed on each ceramic in the same manner as in Example 1. The electrical resistance value and adhesive strength measured in the same manner as in Example 1 are shown in Table 2 below.

[Table] In addition, the surface of the metallized layer has almost no unevenness,
It had excellent smoothness. Comparative Example 1 A paste mixture containing copper oxide powder and metal silver powder obtained in the same manner as in Example 1 was applied to various ceramic sintered bodies in the same manner as in Example 1, and then
900℃ in a reducing atmosphere consisting of a hydrogen-nitrogen mixture
Baked for 30 minutes. Each ceramic having a metallized layer thus obtained and a copper piece were brazed together in the same manner as in Example 1,
When the adhesive strength between the metallized layer and the ceramics was measured, it was less than 50 Kg/cm ² in all cases, and could not be put to practical use. Comparative Example 2 A paste mixture containing copper sulfide powder and metal silver powder obtained in the same manner as in Example 2 was applied to various ceramic sintered bodies in the same manner as in Example 1, and then
950℃ in a reducing atmosphere consisting of a hydrogen-nitrogen mixture
Baked for 30 minutes. Each ceramic having a metallized layer thus obtained and a copper piece were brazed together in the same manner as in Example 1,
When the adhesive strength between the metallized layer and the ceramics was measured, it was less than 50 Kg/cm ² in all cases, and could not be put to practical use.

Claims (1)

[Claims] 1. A mixture of copper oxide or (and) copper sulfide and metallic silver or (and) metallic copper is coated on the ceramic surface, heated and baked at 900 to 1300°C in an oxidizing atmosphere, and then the baked layer is subjected to reduction treatment. A method for metallizing ceramics, which is characterized by: