JPH0336793B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a ceramic metallization method in which a copper compound is baked onto the ceramic surface. [Prior art] Generally, ceramics have good heat resistance, wear resistance,
Although it has excellent insulation properties, it is brittle and weak against shock, so
When used as a structural material, it is often used as a bonded body with metal, and in this case, it is necessary to first metallize the surface of the ceramic before bonding the metal and ceramic. 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, active metal method, hydride compound method, oxide solder method, and copper carbonate method, but methods other than the Telefunken method have complicated processes. In addition, the metallized layer may not have sufficient bonding strength, thermal shock resistance, chemical resistance, etc., so 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 heated again in a non-oxidizing atmosphere to stabilize the coating. The method involves metallizing by heating inside the machine, and then brazing the metals as necessary, which has major disadvantages in that the work process is long and complicated, as well as in that the heating temperature is high. Therefore, the present inventors have already filed Japanese Patent Application No. 58-131575 (Japanese Unexamined Patent Publication No. 60-21888) as a ceramic metallization method to eliminate the above-mentioned drawbacks, and the gist of the invention is as follows. When a mixture of SiO ₂ and at least one of copper carbonate, copper sulfate, copper sulfide, copper oxide, and copper chloride is used as a coating layer, it can be baked at a relatively low temperature in an oxidizing atmosphere such as air, and then the baked layer can be baked at a relatively low temperature in an oxidizing atmosphere such as air. It is extremely easy to metalize by reducing the metallization, and the uniformity of the metallized layer, especially the surface smoothness and gloss, can be improved by using SiO ₂ together.The resulting metallized layer has excellent conductivity and improved bonding strength at room temperature. We were able to make improvements such as: [Problems to be Solved by the Invention] The invention of the present inventors described above improves the bonding strength to some extent at room temperature when metalized ceramics and metal are bonded by mixing SiO ₂ . In particular, it was successful. However, when using a bonded body of ceramics and metal at room temperature, and furthermore at high temperatures of 500°C to 1000°C, there was a drawback that the bonding strength was insufficient. [Means for Solving the Problems] The present inventors have discovered that in order to improve the strength of a bonded body of ceramics and metal at high temperatures, the coefficient of thermal expansion is between that of ceramics and metal, and that of metal. Powders and copper compounds that act as a buffer for the difference between thermal expansion and the thermal expansion of ceramics, have excellent thermal shock resistance, have a high softening temperature, and can withstand continuous use at 1000°C, for example, have the components of crystallized glass. The mixture with the powder is coated on the surfaces of the ceramics to be joined, and the mixture is heated to 900°C in an oxidizing atmosphere such as the air.
We propose a metallization method for ceramics that involves heating and baking at ~1400℃ and then reducing the baked layer. [Function] Copper compound used as a coating layer in the present invention,
For example, copper carbonate, copper sulfate, copper sulfide, copper oxide, copper chloride, etc. are all usually used in powder form. Furthermore, the above-mentioned copperide powder, SiO ₂ , Al ₂ O ₃ ,
Li ₂ O and one or both of MgO and ZnO are mixed with powder of crystallized glass in which 3 to 5% by weight of one or both of TiO ₂ and ZrO ₂ is added. The above-mentioned mixture may be used as it is in powder form, or it may be used in paste form using a suitable binder and its solvent, such as printing ink such as screen oil, balsam, etc. in an appropriate amount. A powder or paste mixture is sprinkled or applied onto the ceramic surface that requires metallization. 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. It is not necessary to use a special oxidizing atmosphere, and it is sufficient to use air, a mixture of air and nitrogen, or the like. 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 heated at a temperature of 900 to 1300° C. for about 5 to 60 minutes. By this heating, copper carbonate, copper sulfate, copper sulfide, or copper chloride is oxidized to copper oxide, and the coating, which is mainly composed of copper oxide, adheres to the ceramic. At this time, the bonding strength is increased by partially penetrating the copper oxide melt into the ceramics. If the heating temperature is lower than 900℃, the above-mentioned penetration will not occur and the bonding strength will be insufficient.
If the temperature is higher than .degree. C., the viscosity of the coating layer may 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 is reduced to metallic copper, such as heating in a reducing atmosphere such as a hydrogen atmosphere or carbon monoxide atmosphere, ethanol, methanol, propanol, etc. Examples include immersion in reducing solvents such as alcohols, benzine, and formalin. When heating in a reducing atmosphere, the temperature is preferably lower than the baking temperature to prevent decomposition and deterioration of the baked layer, and is usually about 200 to 900°C, and the time is usually about 5.
~60 minutes. In addition, in the case of immersion in a reducing solvent, the ceramics may be heated usually to about 200 to 500°C, preferably about 300°C, and then immersed in the reducing solvent for about 10 to 60 seconds. By the above reduction treatment, a copper metallized layer having extremely excellent conductivity is formed on the ceramic surface. If necessary, various metals can be easily joined to the thus metallized ceramics by conventional methods such as brazing. Ceramics that can be metallized according to the present invention are not particularly limited, and include non-oxide ceramics such as silicon nitride, sialon, silicon carbide, and aluminum nitride, alumina, zirconia,
Examples include oxide ceramics such as mullite, beryllia, magnesia, and cordierite. [Example] Example 1 150 [mg] of a mixture of copper oxide powder and powder of the components of crystallized glass shown in Table 1 in the weight percentage ratio shown in Table 2 was added with 0.04 mg of screen oil.
~0.05 [cc] is mixed to form a paste, and a thin film with a thickness of 30 to 80 [μm] is screen printed on the surface of a square sintered silicon nitride (Si ₃ N ₄ ) body to be joined. I twisted it and applied it. Next, use an electric furnace to heat the temperature from room temperature to approximately 1200℃.
After raising the temperature for 40 minutes, it was baked at 120°C for 60 minutes to form a baked coating layer. Furthermore, the fired product was immersed in a liquid containing 5 [g] of dimethylamine borane "(CH ₃ ) HN: BH3" mixed with 100 [cc] of water for 30 minutes at room temperature, and then immersed in hydrogen 13 [/min]. and argon gas 0.8[/min]
500 [℃], 60
A reduction treatment was performed by holding for a minute, and a metallized layer of metallic copper was formed. The metallized layer after reduction has a resistance value [Ω/cm ² ] shown in Table 2 depending on the mixing ratio of copper oxide powder and crystallized glass component powder. Table 2 shows the results of measuring the bonding strength of the metallized layer at room temperature by soldering ceramics on which a metallized layer was formed by the above method to a copper piece using silver solder. As is clear from Table 2, as the weight percentage of the crystallized glass component increases, the bonding strength improves, but on the other hand, the electrical resistance value increases.

【table】

[Table] Example 2 Add 0.04 to 0.05 mg of screen oil to 150 [mg] of a mixture of 70 to 50% by weight of copper oxide powder and 30 to 50% by weight of the crystallized glass component shown in Table 1.
[cc] is mixed to make a paste, and this is made into a flat square sintered body of silicon nitride (Si ₃ N ₄ ), Sialon, silicon carbide (SiC), alumina (Al ₂ O ₃ ), or zirconia (ZrO ₂ ). Thickness 30~80mm on the surface to be joined
A thin film of [μm] was applied by screen printing. The subsequent processing is the same as in the first embodiment. The electrical resistance value of the metallized layer of ceramics with the metallized layer formed by the above method, and the temperature of the joint made by soldering the metallized ceramic and copper piece using silver solder at room temperature and high temperature of 500 [℃] Table 3 shows the bond strength in . In addition,
The values in parentheses are the bonding strengths obtained when the invention described in Japanese Patent Application Laid-Open No. 60-21888 was implemented.

[Table] By mixing a crystallized glass component, the bonding strength at high temperatures is maintained, and the thermal expansion coefficient of the crystallized glass component is higher than that of ceramics (for example, 3.3 × 10 ^-6 /℃ in the case of silicon nitride). ) and metals (for example, 16.6×10 ^-6 /°C in the case of copper), it is thought that the strain caused by the difference in thermal expansion between ceramics and metals can be alleviated. [Effects of the Invention] According to the present invention, a metallized layer can be formed on the ceramic surface by an extremely simple operation of baking at a lower temperature and then performing a reduction treatment than in conventional methods, and the obtained metallized layer has excellent conductivity. In addition, the uniformity of the metallized layer, especially the surface smoothness and gloss, has a high commercial value, as well as the bonding strength when used at room temperature and even when used at high temperatures of 500℃ or higher. can be improved. Since the metalized 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.

Claims (1)

[Claims] 1. Crystallized glass in which 3 to 5% by weight of one or both of TiO ₂ and ZrO ₂ is added to copper compound powder and one or both of SiO ₂ , Al ₂ O ₃ , Li ₂ O, and MgO or ZnO. 900 to 900 in an oxidizing atmosphere.
A ceramic metallization method that involves heating and baking at 1400 degrees Celsius, followed by reduction treatment.