Vol. 41, Issue 1, pp. 247-255 (2011)

Abstract

Laser cutting using the controlled fracture technique has great potential to be used for the separation of brittle materials. In this technique, thermal stress is used to induce the crack and the material is separated along the moving direction by extending the crack. In this paper, based on the heat transfer theory, a three-dimensional thermoelastic finite element model which contains a pre-existing crack is established for a two-point pulsed Nd:YAG laser cutting silicon wafer. The mechanism of crack propagation is investigated. Meanwhile the effects of laser power and the distance between the two laser spots on the development of thermal stress are investigated. The numerical results show that the thermal stress is affected by laser power and the distance between the two laser spots, an increase in the laser power for the same distance between the two laser spots or a decrease in the distance between the two laser spots with constant laser power can induce the increase in the cutting speed.