Component fatigue in power electronics

The development of power electronics in new fields of use is leading to an increase in the levels of functional and environmental stress applied to power modules (automotive, aerospace, etc.). As a result, numerous technological breakthroughs are being developed to meet the sometimes contradictory objectives of cost control, weight and size reduction, while improving specifications in terms of maintainability and reliability.

However, a number of obstacles limit the use of the requirements defined in the field of operating safety, and more specifically, for assessing the reliability of integrated power semiconductor devices. In fact, reliability assessment, which is inseparable from the statistical approach, is made tricky by the long objective lifetimes with low failure rates, the many technological developments and the low production volumes of power semiconductor systems.

The approach presented in this dossier offers an introduction to assessing the robustness of power semiconductor assemblies based on an understanding of the physical degradation leading to failure, with :

• presentation of the components of a conventional power assembly and the main fields of application;

• in relation to the imposed mission profiles, the state-of-the-art defect of the main degradation modes leading to failures mainly of thermomechanical origin;

• in the sense of the physics of failure approach, a presentation of the main damage mechanisms and factors, and the means of revealing them.