In this course, the continuously growing importance of power electronics and the need for long and reliable power semiconductor devices will be addressed. First, an introduction to the most widely used power semiconductor devices will be given with a short introduction to its operation principle. Then, the role of the parasitic elements and thermal stresses in real applications, without forgetting about abnormal operations such as short-circuit will be addressed. With the target of accelerating the transition towards long-term lifetime of power electronic systems, four golden rules for reliable power module design will be proposed, which includes reliable operation under both normal and abnormal conditions. On the second day, an overview of the most common failure mechanisms in silicon IGBTs and SiC MOSFETs will be presented. The prediction of such failure modes is complex since they can be triggered due to many parameters, such as temperature, voltage variation, inductive and capacitance effects, unbalanced current distribution and also EMI (Electro Magnetic Interference). Examples of instabilities will be given and the PhD student will become familiar with the failures that one can find in the field. The student will learn through a software tool, such as PSpice, how to model abnormal operations aiming at increasing the device robustness.