Productivity Enhancement in Laser Induced Plasma Micromachining by altering the Salinity of the Dielectric Media

Abstract

Laser Induced Plasma Micromachining (LIPMM), a recently pioneered micromachining process, offers higher material removal rates and greater aspect-ratios of machined features as compared to laser ablation, while preserving its higher resolution and precision as compared with mechanical (tool-based) micromachining processes. LIPMM involves focusing a pulsed laser beam within a transparent liquid dielectric such as distilled water to induce optical breakdown, and is hence greatly influenced by the dielectric?s thermo-electrical properties.This study presents a possibility for process improvement by modifying the dielectric medium composition to target higher material removal rates, aspect ratios and other desirable machining characteristics. We report the influence of salt concentration in distilled water, to achieve greater feature depths and material removal rates in surface micro-machining of Aluminum by the LIPMM process. The key results of this study show up to 100% increase in depth at an optimum salinity of 2-4 g/100 ml. Also, the machining characteristics correlate with the plasma generation thresholds for the corresponding salinities.