In this article, the failure behavior of DMOS switches under repetitive clamping stress is shown to be dominated by thermomechanical deformation of the metallization. Electromigration stress is not a significant factor in the failure. This was verified with special stress tests, and the thermomechanical characteristics were furthermore highlighted by FEM simulation. Based on these findings, a novel metallization system that significantly improves the fast temperature cycle reliability is described. (C) 2008 Elsevier Ltd. All rights reserved.