An Investigation into Laser Ablation of Copper films with a Nd:YAG Laser
S. Shamsaei, M. Ghoreishi and Y. Javid
In pulsed laser material removal systems it is very important to understand the ablation mechanism that take place during the laser ablation process. A two-dimensional (2-D) model is developed to investigate the ablation rate and stress values for a copper target material by a nanosecond laser pulse. The model takes into account the absorption of the laser beam, and heating and vaporization of the target, including an adjustment to compensate for the change of state. The finite element method was employed to describe the major physical processes taking part in the laser ablation process. The stress distribution in the target material during the pulse duration is also analysed. The effect of the laser on the resulting material removal rate and residual stress distribution is investigated in detail. The calculated maximum surface temperature of the target is higher than the estimated value of copper critical temperature, corroborating the hypothesis that the ablation mechanism is explained by the explosive boiling. The results of this research can be used in improving and optimizing the micro-machining capabilities of the process.
Keywords: Nd:YAG laser, laser ablation, copper, finite element simulation, von Misses stress, residual stress