Production of molybdenum disc
Because of its high strength, good thermal conductivity and good processing performance, molybdenum is used as the substrate material of silicon rectifying elements and silicon controlled silicon components (the support of silicon wafer molybdenum disc). At present, there are three production methods of molybdenum disc: (1) molybdenum bar cutting machine processing; (2) molybdenum powder direct pressing, sintering machining; (3) molybdenum plate punching machining. Among them, the production method of molybdenum bar cutting is still in the experimental research stage, and there are some defects that are difficult to overcome temporarily; however, although the yield of molybdenum powder direct pressing and sintering production method is high, the product density is slightly lower, the grain structure is disorderly arranged, and the strength is slightly poor. In the use, users find that it is easy to produce cracks or fractures when it is compounded with silicon wafers with high-purity aluminum diffusion. At present, most of the power semiconductor device manufacturers use the molybdenum plate punching method to produce molybdenum discs. The molybdenum discs produced by this way have the characteristics of high density (close to the theoretical density), fine fiber structure, good room temperature plasticity and high strength, so the main production mode is adopted.
The key technology of producing high quality molybdenum discs is to control the quality of raw materials, standardize the operation process and adopt reasonable production technology. The key to improve the surface quality of molybdenum disc is to control the production quality of the end face grinding process. Selecting the advanced four-way double-sided lapping machine can make the surface quality precision of the products reach the world advanced level.
