Micromachining of stainless steel-polymer composites using nanosecond and femtosecond UV lasers

Abstract

The fabrication of microstructures using high-strength anti-corrosive materials is a topic of intense investigation. In this work, we investigate micromachining processes for fabricating stainless steel-polymer composites using nanosecond (excimer) and femtosecond (Ti:sapphire) lasers at ultraviolet wavelengths. The laser ablation mechanisms were analyzed as a function of the laser source and process parameters. Microdrilling and grooving of the composite were used to evaluate the process performance. The ns laser processing mechanism at relatively low fluences relied mainly on ablation with photothermal/photochemical decomposition of the binder resin without permanently affecting the stainless steel particles. On the other hand, ns laser pulse irradiation at high fluences induced significant melting and agglomeration of the particles, which lowered the ablation rate and were detrimental to the micromachining performance. During the high-intensity femtosecond laser processing (> TW/cm(2)), the laser pulse directly ablated the particles and the binder without inducing significant thermal effects. Microstructures 10 mu m in size (average particle size) and with an aspect ratio of similar to 10 were fabricated.