The effect of laser welding on LIGA materials

Abstract

An increasingly important production process for microminiature mechanical parts is the LIGA process. LIGA parts (with in-plane features from a few μm to several mm) are electroplated into lithographically-produced molds. In this paper we shall show the effect of pulses of laser energy used to spot weld LIGA-produced parts. As-plated LIGA material is exceptionally fine grained, and has high hardness and mechanical strength. Presence of appreciably weakened heat affected and/or fusion zones, or porosity in such a part could seriously affect its service performance. An examination of laser and resistance spot welds on LIGA Ni, and laser welds on LIGA Ni-Fe and Ni-Co alloys by metallography and microhardness traverses is reported. Issues of heat input, thermal cycles, recrystallization kinetics, pore formation and final mechanical properties are discussed.An increasingly important production process for microminiature mechanical parts is the LIGA process. LIGA parts (with in-plane features from a few μm to several mm) are electroplated into lithographically-produced molds. In this paper we shall show the effect of pulses of laser energy used to spot weld LIGA-produced parts. As-plated LIGA material is exceptionally fine grained, and has high hardness and mechanical strength. Presence of appreciably weakened heat affected and/or fusion zones, or porosity in such a part could seriously affect its service performance. An examination of laser and resistance spot welds on LIGA Ni, and laser welds on LIGA Ni-Fe and Ni-Co alloys by metallography and microhardness traverses is reported. Issues of heat input, thermal cycles, recrystallization kinetics, pore formation and final mechanical properties are discussed.