Analysis of Laser Weld Induced Stress in a Hermetic Seal

Abstract

Laser welding of glass-to-metal electrical connectors is a common manufacturing method for creating a hermetically sealed device. The materials in these connectors, in particular the organic glass, are sensitive to thermal induced residual stress and localized heating. An analytical laser weld model is developed that provides simulation and analysis of both thermal and mechanical effects of the welding process. Experimental studies were conducted to measure the temperature at various locations on the connector. The laser weld is modeled using both surface and volumetric heating directed along the weld path to capture the thermal and mechanical response. The weld region is modeled using an elastic-plastic weld material model, which allows for compliance before welding and stiffening after the weld cools. Results from a finite element model of the glass-to-metal seal are presented and compared with experimental results. The residual compressive stress in the glass is reduced due to the welding process but hermeticity is maintained.