Study on Fine Boring of Single Crystalline Silicon by EDM

Micro machining of brittle materials such as silicon or ceramics is difficult by traditional machining method, since stress generated at machining point causes cracks and fractures. EDM is performed by repetition of micro crater produced by a single discharge and machining force is very small. Therefore, EDM might be used for micro machining of single crystalline silicon. In this paper, EDM characteristics for fine boring of single crystalline silicon were experimentally investigated.Main conclusions obtained in this study are as follows:1) EDM can be carried out for single crystalline silicon whose specific resistance is less than about 10-2Ω·cm.2) The removal rate for single crystalline silicon is 2-10 times as high as that of SUS304.3) In deionized water, the removal rate with copper electrode is 5-10 times higher than that with tungsten electrode.4) The adhesion of silicon to the electrode surface in the normal polarity EDM is remarkable as compared with that in the reversed one, which leads to lower removal rate under the same setting condition.5) The shape of micro hole is better in kerosene type fluid, while the removal rate is 15 times lower than that in deionized water.