Study on ablation properties of PDMS by 193 nm and 248 nm excimer laser

Abstract

Laser direct writing technology was a convenient and efficient method in micromachining, which was widely used in polymer processing. In this paper, two kinds of excimer laser (193 nm and 248 nm) were used to irradiate vertically the surface of polydimethylsiloxane (PDMS) for ablation experiments. The experiments were carried out in atmospheric environment, and the ablated samples were characterized by optical microscope, laser confocal microscope, white light interferometer, scanning electron microscope, etc. to obtain their morphology. Analysis was performed on the effects of laser energy and pulse numbers on depth, roughness, and morphology. The outcomes demonstrated that, the crater depth and roughness increased as the number of pulses and energy increased, but that the bottom surface's roughness did not continuously increased with the ablation of a 248 nm laser. At low energy, the roughness remained constant as the number of pulses increased. When the laser operating voltage was adjusted to 23 kV, the roughness increased linearly with the number of pulses. As the laser energy and the number of pulses increased, the number of splashes deposited on the ablation surface increased. Cracks were generally observed across the PDMS surface after a 248 nm laser and the crater edges were rough. The morphology in the 193nm laser ablation showed better micromachining quality, reflected in a small number of pores, sharp edges, and smoother bottom surface.