Thermal analysis of laser drilling processes

A model has been developed that uses a continuous, distributed, and moving heat source to describe the temperature profile and thermal stress propagation for laser drilled holes in high-purity fired-alumina ceramic substrate material. The temperature profile and the tangential stress distribution of the laser-formed hole are calculated to indicate the magnitude of those factors that can influence the potential fracture of the alumina material. These factors are of interest in order to help establish optimum laser-drilling parameters. Experimental data are obtained from the ruby and CO2lasers operated in the pulsed mode. The experimental results are found to be in excellent agreement with the theoretical analysis.