Abstract
Pulsed laser ablation is one of the most efficient and clean methods for high-precision processing and modification ofpolymers and biomaterials. Polymer ablation has been extensively investigated with ultraviolet lasers while little at-tention has been given to the infrared (IR) region, which becomes particularly interesting with the recent advances inultrashort laser technologies.
Here, we report the resultsof a comparative study on 1030-nm ultrashort laser structur-ing of Kapton polyimide, a polymer important in a variety of applications, with direct comparison of 247-fs and 7-pslaser pulses. The laser-induced damage thresholds for bothpulse durations have been determined and the femtosecondlaser threshold has been found to be considerably lower thanthat for picosecond pulses (by a factor of ~3.5).
Bothfemtosecond and picosecond laser-produced craters have been thoroughly investigated as a function of pulse energyand focusing conditions. It has been demonstrated that femtosecond laser pulses enable accurate polyimide structuringwhile picosecond irradiation regimes result in a number of undesired effects such as re-deposition of the ablation debris,surface swelling, and the formation of high rims around the ablation craters.
The mechanisms of polyimide ablationwith femtosecond and picosecond IR laser pulses are discussed.