Control of Kerf Width in Multi-wire EDM Slicing of Semiconductors with Circular Section

Multi-wire EDM slicing method have been developed to overcome problems of conventional multi-wire saw method, and high-efficient and high-accurate slicing could be expected compared with a single-wire EDM technologies. Recently, a group power supplying method was newly proposed to satisfy both processing efficiency and simplification of slicing equipment, and it can supply sufficient discharge energy to multiple processing wire electrodes only using one conductivity piece set with one EDM power unit. Input energies were almost constant at each processing wire electrode, and electrical discharge pulses could be homogeneously distributed to each processing point without the wire breakage even by using only one conductivity piece set in the group power supplying method. This multi-wire EDM slicing method with the group power supplying can slice materials into many wafers of a certain thickness according to the pitch distance of processing wire electrode. In this method, it is important to perform the uniform kerf width in order to achieve a constant thickness of wafer. However, the cutting width of workpiece always varies in the case of silicon and silicon carbide ingots with circular cross section. Therefore, influence of cutting width of workpiece on slicing characteristics was experimentally investigated to achieve the uniform kerf width. The maximum feed rate of workpiece had a great influence on the kerf width with different cutting width of workpiece, and a larger kerf width was obtained with decreasing the cutting width of workpiece under a constant maximum feed rate condition. A uniform kerf width could be obtained by setting a half and quarter maximum feed rate of workpiece, although the cutting width of workpiece increased by twice or four times.