Pulsed Nd:YAG Laser Closure Welding of the MC3593/3594 Relay

摘要

The pulsed Nd:YAG laser welding process is often chosen today for closure welding of small hermetically sealed electrical devices. This is because it is a high power density welding process that can minimize total heat input and therefore is less likely to damage heat sensitive components. The effect of the pulsed Nd:YAG laser welding parameters on the incidence of glass-to-metal seal cracking and on the weld fusion zone dimensional parameters for the MC 3593/3594 relays has been determined. Fluctuations in weld penetration in production relays have been attributed to variability in sharp focus positioning. A large increase in blowholes and porosity in the fusion zone has been traced to the inadvertent substitution of 304 stainless steel for 304L stainless steel header material. The blowholes and porosity are thought to result from a carbon-oxygen gas reaction in the weld pool due to the presence of a 4% oxygen atmosphere and the increased carbon content of the 304 stainless steel. (ERA citation 12:025482)