Theoretical and experimental investigations into laser ablation of polyimide and copper films with 355-nm Nd:YVO4 laser

The micromachining of thin films multi-layered with metal and polymer is of great interest due to the superior flexibility and high conductivity of these films. Laser ablation of these laminated materials is a combination of the photochemical evaporation and the photothermal melt expulsion. In the ablation of metal, the photothermal effect is dominant, while in the ablation of polymer the photochemical effect is more intense. In this paper, in order to predict the etching depth the laser ablation of polyimide (PI) and copper (Cu) films, we adopted a theoretical model, called the Srinivasan-Smrtic-Babu (SSB) model, which considers both the photothermal and photochemical effects. The model parameters were obtained by fitting the experimental data from sources in the relevant literature. We used a 355--nm DPSS Nd:YVO4 laser to carry out a laser ablation of PI and Cu films. In experiments, we examined the effects of laser fluence on the quality of the ablated surfaces. Experimental results showed that at laser fluence lower than the threshold energy, high-quality surfaces with no burr or deformation were achieved. (c) 2006 Elsevier B.V. All rights reserved.