Surface Modification of Polytetrafluoroethylene via Laser-induced Plasma Etching (LIPE)

Laser-induced plasma etching (LIPE) offers a promising technique for high-quality surface processing under atmospheric pressure.This study investigates the surface modification of polytetrafluoroethylene (PTFE) in air using a high-repetition-rate ultrashort pulsed laser.Key process and laser parameters, including repetition rate, pulse energy, plasma-to-surface distance, and etching time, were analyzed for their impact on etching rates and surface morphology.The etching rate of PTFE under stationary conditions was measured in the picometer-per-pulse range, enabling precise vertical control.Results show that etching rates increase with increasing pulse energy and repetition rate but decrease with greater plasma-to-surface distances.The generated etch grooves are circular and significantly larger than the laser spot size, with etched surfaces exhibiting reduced surface roughness compared to unetched surfaces.Line pattern etching was demonstrated by moving the sample at a constant speed in front of the laser-induced plasma.Unlike laser ablation, LIPE achieves superior vertical depth precision and significantly smoother surface morphology, making it a valuable tool for ultra-precise surface machining applications.