Discharge Multiple Cutting Technology Forspecific Crystallographic Planes Of Monocrystalline Silicon

The surface of monocrystalline silicon is often required the specific crystallographic planes in practice, such as diffraction crystal, which can monochromatize polychromatic light. Diffraction crystal is the core unit of optical detection equipment. The requirement of the surface quality and the crystallographic orientation accuracy are very high. Electrical discharge machining(EDM) has no macroscopic force which is not restricted by material hardness, which is very suitable for hard brittle monocrystalline silicon.This paper combined the discharge cutting for specific crystallographic planes of monocrystalline silicon with multiple cutting technology to improve the surface quality and machining accuracy. The removal process was discussed by using single pulse discharge system. The machining surface quality of different energy was analyzed. Based on the analysis, reasonable cutting parameters of multiple cutting were find out and the machining surface quality was improved. Meanwhile, the improvement of the crystallographic orientation accuracy by multiple cutting was verified. The machining with high surface quality and high crystallographic orientation accuracy was achieved.In this paper, the specific research contents are as follows:(1) Discharge cutting for specific crystallographic planes of monocrystalline silicon is combined with multiple cutting technology for the improvement of the surface quality and crystallographic orientation accuracy.(2) The single pulse discharge system of silicon was established. The discharge pits of different discharge energy was observed by single pulse discharge experiments. Three erosion forms- thermal erosion, stress erosion and secondary breakup were found.(3) Surface roughness, microstructure and damaged layer thickness of different discharge energy by WEDM were studied. Based on the analysis, reasonable cutting parameters of multiple cutting were find out. The machining surface quality was improved and the finishing allowance was reduced by multiple cutting. Under the same surface quality, the 90% of the machining time was shortened.(4) The crystallographic orientation accuracy was improved and the crystallographic orientation error fluctuation was reduced by multiple cutting.(5) The machining efficiency was improved by preparing Ohmic contact by the surface discharging of input terminal. The large-size products with specific crystallographic planes were obtained.