2. Thermal fatigue and reliability

2.1 Thermomechanical effects and thermal fatigue

By their very nature, power components and their assemblies have to operate in conditions where their temperature is subject to significant fluctuations. These temperature fluctuations may be due to variations in ambient temperature, self-heating, or a combination of both. This is particularly true of electronic equipment installed on rolling stock (cars, trains, aircraft, etc.). From a mechanical point of view, components, their housings and heat sinks form a heterogeneous assembly linking together materials that can be characterized by very different coefficients of thermal expansion and dispersed mechanical properties, as shown in the table 1 taken from the Matweb...