Silicone Gel Filled Power Module for Harsh Environment Applications: A Case Study on the Gel and Case Material Interaction

Gel-filled power modules are widely used in automotive and industrial applications. Due to process limitations and reliability concerns epoxy molded power modules are not suitable when the module size increases. Silicone gel-filled power modules are widely used as a viable alternative. Silicone gel is used to protect the die and interconnection from mechanical and environmental damage in these modules. However, this limits the module application in harsh environments such as very high humidity-temperature and sudden shifts in these conditions. Field failures in gel-filled modules from the China (Middle-Eastern region) have been reported recently. Initial investigation with an in-house experimental setup indicated that silicone gel that was subjected to high humidity and temperature environment showed a similar failure mechanism reported from the field. Two hypotheses were suggested for the field failure. This paper describes the work done to validate these hypotheses and the development works to identify the root causes and possible silicone gel material solution.