Excimer laser induced conductivity on silver salt filled polyimide films

The optical transmission, electrical resistivity, developed surface structures and chemical properties of KrF excimer laser irradiated normal and organic silver salt containing polyimide samples are compared. It is demonstrated that there exists a connection between the changes of optical transmission and electrical resistivity. The dependence of the threshold number of pulses of resistivity decrease on silver salt concentration is proved. Scanning electron microscopy reveals that the conical structures developed on the surface of both samples after UV treatment show significant deviations in both structure and dimensions. Normal and filled foils possess significantly different C(1s) XPS spectra. The Ag(3d) spectrum of filled sample shows that the amount of the silver decreased almost to zero after 1800 pulses in the surface layer. This observation suggests that most probably the silver atoms do not play a significant role in controlling the changes in electrical resistivity of the filled samples.