Discussion on the Test Methodologies for Structural Integrity of Power Module

Abstract

Thermal fatigue of wire-bonding and die-attach materials is a critical factor in the structural integrity of power modules. A power-cycling test, a temperature-cycling test and a mechanical-fatigue test are utilized to evaluate the expected lifetime of power modules. Moreover, lifetime evaluation in the design phase is considered to be important for power modules incorporated into mass-produced commodities such as automobiles and home appliances, because in-service condition monitoring is difficult for power modules used in such commodities. In this paper, we consider a power-cycling test and a temperature-cycling test, and discuss the applicability of the lifetime evaluation formulae obtained from these tests to evaluating the lifetime of power modules in the design phase. In addition, we discuss a mechanical-fatigue test as a substitute for a temperature-cycling test.