Basic Research On Resistance Properties Of Silicon Crystal And Piercing By Electrical Discharge Machining

Semiconductor has become the most active material in application of advanced technology for its unique physical and mechanical properties, especially in aerospace industry,optics area and electronic area. Among them, silicon and germanium are the most widely used crystals. However, most of the semiconductors are hard-brittle materials which are easy to break in processing, this causes the poor processability of them. Thus, traditional machining could not meet its technological requirements. How to achieve the HSC process of them (cutting,piercing,forming etal) is a topic for heated research. The subject research the EDM of semiconductor silicon. Based the different physical properties and electrical characteristics of conductor and semiconductor, the inter-electrode resistance properties and the one-way conductivity of P-type silicon semiconductor in electrical discharge machining were studied, then discusssed the method of improving the discharge capacity of silicon under EDM. Baised on this, through the establish of the EDM model of semiconductor silicon, the EDM piercing test of P-type silicon was conducted under discharge experimental platform.Main of this subject:1,Research inter-electrode resistance in electrical discharge machining basing on and the effects on machining, and put forward semiconductor EMD processing in order to improve process conditions. The conduction mode is studied from point,line and surface based on the testing, and surface is found to be the best way. From it we know improving the conduction mode (such as increasing the effective contact area of condution) can reduce the inter-electrode resistance and improve the discharge current.2,By analyzing the schottky contact barrier which was formed between semiconductor and metal materials, the discharge piercing machining principle model of P-type silicon and the equivalent circuit diagram of the DR was established. Then model was introduced from the discharge channel, the electrical side contact, discharge side contact, body resisitance.3,The the one-way conductivity characteristics of PN junction and schottky junction was discussed. Through the experiments, one-way conductivity characteristics of semiconductor silicon in the discharge machining was studied and its discharge machining polarity was selected reasonably. It is found that positive polarity processing method can improve the P-type silicon EDM currents, which will lay a foundation for improving its EDM capacity.4. Design a discharge experimental platform and a pragmatic piercing device, and choose the reasonable P-type silicon location,clamping,conduction mode,machining polarity and working liquid circulation system, then the EDM piercing test of P-type silicon was conducted which researched the influence of electrical parameter on piercing speed and the electrode wear. Then the machining accuracy and current wave were studied, which will lay foundation for the study of the discharge process of other semiconductor materials and the mechanism of electrical discharge machining of semiconductor.