Research On The Wire-cut Electrical Discharge Machining Of Silicon Materials Based On Reciprocating Progressive Motion Control

Monocrystalline silicon wafers are widely used in the photovoltaic industry and microelectroniccomponents. WEDM(Wire cut Electrical Discharge Machining) process the materials with thecorrosion phenomena generated by spark discharge. WEDM technology without macro machiningforce is very suitable for the processing of brittle semiconductor materials. After many years of hardwork, researchers already have a certain understanding for the mechanism, features and process ofsemiconductor WEDM, forming a relatively complete theoretical system and parameters data base.Semiconductor with a certain range of resistivity can be processed now. At present the biggesttechnical problem in semiconductor WEDM processing is automatic servo control. The specialelectrical properties of silicon material make the traditional method used in servo control system forWEDM fail to detect discharge status. Therefore, a reciprocating progressive adaptive control methodby means of back and forth feed motion is proposed. Theoretical study and practical research aredeveloped. based on this method. Specific works are as follows:(1) The current and voltage characteristics of silicon materials WEDM were studied, bycomparing with those of metallic materials. And based on these characteristics, failure reasons ofexisting WEDM servo systems in semiconductor material processing were analyzed. On the basis ofthat, a reciprocating progressive adaptive control method is proposed.(2) An adaptive control algorithm based on fuzzy control for the relative parameters inreciprocating progressive adaptive control method was proposed. An adaptive fuzzy logic controllerwas designed and simulated on MATLAB.(3) Hardware at current machining was reformed, analog detector circuit with OCisolation,discharged current detection circuit and interface circuit of linear encoder were designed. Aclosed-loop servo motion controller of WEDM which consist of IPC and motion controller was build.(4) Configuration of motion controller and design and debugging of reciprocating progressiveadaptive control program were accomplished. Control interface based on Windows was designed byusing VISUAL C++. Thus, WEDM real-time status can be monitored.WEDM experiment with silicon materials based on the reciprocating progressive adaptivecontrol method was done. The experimental result shows the proposed new method has itseffectiveness and superiority compared with traditional method. The reason that the proposed new method is good at reducing communicating stripes was analyzed.