Fiabilité environnementale des composants de puissance : le TRIAC

The work presented in this thesis consists in the thermo-mechanical reliability study of power components submitted to temperature cycling tests (TCT) or thermal shock tests (TST). TCT and TST were compared from the component reliability point of view. The influence of dwell times and maximum temperature was investigated. TCT and TST seem to be equivalent because they produce the same degradation at the same location (cracked base plate – ceramic solder joint). These observations are validated by statistical analyses and 3-D simulations. Simulation results allow us to confirm the failure mechanism — solder joint between base plate and ceramic is worn out by shear — and to help us to bring out the effect of dwell times and temperature extremes. Thus, dwell times produce negligible impact in comparison of temperature extremes. From the determination of fatigue models constants and the supplying of a mission profile (real temperature profile), lifetime estimation can be performed.