JPS60221380A - Metallization of silicon carbide sintered body - 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] [Field of Application of the Invention] The present invention relates to a method of metallizing silicon carbide unsintered substrates,
In particular, it relates to high-temperature baking metallization.

[Background of the invention]

Conventionally, various methods have been used to metallize silicon carbide unsintered substrates, such as conductive glass paste baking method and metal paste high temperature baking method, but metal paste high temperature baking method is used for those that require adhesive strength. Ru. For example, for molybdenum metallization, molybdenum paste is applied to a silicon carbide unsintered substrate, and after drying, it is placed on an alumina setter.
It is fired at about 1400 r in a forming gas of nitrogen and hydrogen.

However, the unsintered silicon carbide substrate metallized by this conventional method is partially altered in quality, has carbonization, and has spots on the surface of the unsintered substrate, resulting in a decrease in the resistance of the substrate surface. Another problem is that it is easily affected by the temperature distribution within the furnace.

[Purpose of the invention]

An object of the present invention is to solve the problems of the prior art described above and to provide a method for metallizing a silicon carbide unsintered substrate that is free from deterioration or spots and does not cause a decrease in the resistance of the substrate surface.

[Summary of the invention]

The inventors investigated the causes of deterioration of the unsintered silicon carbide substrate when using the above alumina setter, the decrease in substrate surface resistance due to spots, and the reasons why the substrate is easily affected by the temperature distribution in the furnace. As a result, the unsintered silicon carbide substrate reacted with the alumina setter at the part where it was in contact with the setter (on which the SiC sintered substrate is placed during the firing process of the metallization process), resulting in deterioration of the unsintered silicon carbide substrate. This is because silicon carbide unsintered substrates tend to react at temperatures of around 1400 U, causing spots to form as a result of reacting with floating impurities in the furnace, and the poor thermal conductivity of the alumina setter. We found that the cause is easily influenced by distribution. However, we have found that a good metallized product can be produced by using a setter made of silicon carbide yarn that does not easily react with the unsintered silicon carbide substrate at a temperature of about 1400 U and in a forming gas of nitrogen and hydrogen.

The present invention has been made based on such knowledge, and when carbonizing a silicon carbide sintered substrate to metallize and fire it, at least the portion in contact with the SiC sintered substrate is the same as that of the unsintered silicon carbide substrate. The setter 1 is characterized by using a ceramic setter 1 made of the material SiC or more than 90 inches.

In the present invention, the setter is preferably made of the same material as the broken metallized material or a ceramic made of silicon carbide with a thickness of 90 or more. More preferably, the setter has a structure that can cover the entire substrate to be metalized during metallization firing.
This is good because it prevents contamination caused by floating impurities.

The surface resistance of the SiC sintered body obtained by the metallization of the present invention is 10<12 >Ω/hole or more at an electric field strength of 500 V/sub.

[Embodiments of the invention]

Example 1 Molybdenum paste was printed on one side of a silicon carbide unsintered substrate containing beryllium oxide 2Wt4, and after drying, it was placed on various setters shown in Table 1 and heated at 1400U-1h in a forming gas of nitrogen and hydrogen. It was fired in The results are shown in Table 1, and in all cases, except for the setter containing 90% or more of silicon carbide, the substrate changed in quality, the substrate surface resistance decreased, or the substrate reacted and adhered to the setter.

Table 2 Example 2 Molybdenum paste was printed on one side of a silicon carbide unsintered body substrate containing PeIJ IJium 2Wtl oxide, and after drying, a box-shaped setter and a plate-shaped setter were printed as shown in FIGS. 1 and 2. As a result of firing in a forming gas of nitrogen and hydrogen at 1400C for 1 hour, no deterioration of the substrate or spots on the substrate surface were observed when using a box-shaped setter.

Example 3 Silicon carbide unsintered body substrate containing 2 wt% beryllium oxide (
After drying, 200 sheets each were placed on an alumina setter and a silicon carbide burner setter, kept at the temperature shown in the figure for 1 hour, and heated with nitrogen and hydrogen. As a result of firing in forming gas,
As shown in the figure, the variation in adhesive strength is smaller when using a silicon carbide sintered body setter, because the thermal conductivity of the silicon carbide unsintered body is 270 W/mK and that of alumina is 28 W/mK. /mK, which is large compared to the above, and it is thought that the influence of temperature distribution in the furnace can be reduced, which reduces the variation in adhesive strength.

[Brief explanation of the drawing]

FIGS. 1 and 2 are structural diagrams of the setter, and FIG. 3 is a diagram showing temperature and adhesive strength.

Claims (1)

[Claims] 1. The surface resistance of the metallized silicon carbide unsintered body is 50.
A method for metallizing a silicon carbide unsintered body, characterized in that the electric field strength is 1012Ω/or more at an electric field strength of 0V/crr1. 2. In claim 1, at least a portion of the setter that contacts the unsintered silicon carbide substrate as a setter on which the unsintered silicon carbide substrate is placed during the firing operation in the metallization process is an unsintered silicon carbide substrate. Same material as the board or 90
A method for metallizing silicon carbide unsintered bodies, characterized by using ceramics containing silicon carbide of % or more. 3.% Permissible scope In claim 1, the silicon carbide unsintered body contains silicon carbide whose main component is α-8iC and 0.05 to 0.05%.
A method for metallizing a silicon carbide unsintered body, comprising 3.5 parts by weight of beryllium and a beryllium compound.