Excimer laser ablation of polycarbonate-based plastic substrates

Ablation of polycarbonate-based plastics under excimer laser irradiation has been studied, with emphasis on the influence of specific inorganic additives in the polymer to the ablation process. Such additives consisted of 0.2 μm sized, (spherical) TiO 2 grains, in either 5% or 10% mass concentration. Irradiation products are analyzed, with respect to roughness and ablation, by scanning electron microscopy, energy dispersive X-ray spectroscopy and stylus-profilometry. In the surface region (0–5 μm) of the plastic substrate (i.e. where additives are nearly absent), single pulse irradiation at fluences below 1 J/cm 2 yields no ablation and induces the formation of a spongeous polycarbonate medium. Upon repeated irradiation, ablation of this medium proceeds and gives access to the additive-containing material. Evidences are then obtained for subsequent ablation and for a particular structuring of the TiO 2-containing material surface in the form of roll-forming cells. The cell formation is indicative of irradiation-monitored melting of the polymer and phase separation between additive and polymer.