Application of millisecond pulsed laser welding in MEMS packaging

Abstract

This paper reports a new packaging method for a wide range of MEMS applications on both the wafer and device scale. Titanium is used as the packaging material in this work and both Si-MEMS and Ti-MEMS devices are integrated into a 350 µm titanium substrate. A Nd:YAG pulsed laser is used as a localized heating source to micro-weld a 350 µm titanium cap to the substrate. Simulation of the heat conduction of a two-dimensional time-dependent pulse laser between the substrate and cap was carried out using COMSOL to investigate pulsed laser melting properties. To avoid thermal distortion of the welding, several geometries at the cap and substrate interface were investigated to minimize laser intensity in order to achieve the required melting depth.