Study on surface characteristics using phosphorous dielectric on wire electrical discharge machining of polycrystalline silicon

In this study, wire electrical discharge machining (WEDM) was implemented to process polycrystalline silicon ingot (electric resistance, 2-3 Ω cm), and the influences on surface characteristics were examined. At first, two different dielectrics, pure water and pure water with sodium pyrophosphate powder, were experimented to compare their effects on cutting speed and surface roughness. In the experiment, pure water with sodium pyrophosphate powder has shown that it enhanced process efficiency and improved surface smoothness. Then, the effects on cutting efficiency with different concentrations were examined; 0.05 M was chosen for its best performance. After setting the concentration, several experiments were conducted to find out how different currents and pulse-on times affect the cutting efficiency and surface roughness. The findings in this study prove that using phosphorous dielectric on WEDM could be applied onto polycrystalline silicon cutting. In addition, pure water with sodium pyrophosphate powder increases both working efficiency and improves infiltration of the phosphorous element on the surface. These findings could be future references on researches of solar cell in both industrial and academic fields.