Silicon carbide substrate:
a. Raw material: SiC is not naturally produced but is mixed by silica, coke and a small amount of salt, and the graphite furnace is heated to more than 2000 ° C, and the A -SIC is generated. Precautions, a dark green block-shaped polycrystalline assembly can be obtained;
b. Manufacturing method: The chemical stability and thermal stability of SiC are very good. It is difficult to achieve densification using common methods, so it is necessary to add a sintered aid and use special methods to fire, usually by vacuum thermal pressing method;
c. Features of the SiC substrate: The most distinctive nature is that the thermal diffusion coefficient is particularly large, even more copper than the copper, and its thermal expansion coefficient is more close to Si. Of course, there are some shortcomings, relatively, the dielectric constant is high, and the insulation withstand voltage is worse;
D. Application: For silicon carbide substrates, long extension, multiple use of low voltage circuits and VLSI high cooling packages, such as high speed, high integration logic LSI tape, and super large computers, Light communication credit laser diode substrate application, etc.
Case substrate (BE0):
Its thermal conductivity is more than a twice as A1203, which is suitable for high-power circuits, and its dielectric constant is low and can be used for high frequency circuits. The BE0 substrate is basically made of a dry pressure method, and may also be produced using a trace amount of MgO and A1203, such as a tandem method. Due to the toxicity of the BE0 powder, there is an environmental problem, and the BE0 substrate is not allowed in Japan, it can only be imported from the United States.