TEA CO2-LASER ABLATION OF UPILEX POLYIMIDE

We report an experimental investigation of the absorption and ablation characteristics of the high-temperature polymer Upilex polyimide, usi ng a line-tunable TEA CO2 laser. It is demonstrated that excellent qua lity through-holes (vias) can be produced in thin films of Upilex when the CO2 laser is tuned to a strongly absorbed wavelength as a result of thermal decomposition produced by laser heating of the bulk polymer . For weakly absorbed wavelengths, transmission and probe beam deflect ion measurements reveal an incubation effect in the ablation which is thought to be related to particulate contamination in the film.