Cosmic radiation has been identified as a decisive factor for power device reliability. Energetic neutrons create ionizing recoils within the semiconductor substrate which may lead to device burnout. Originally, this failure mechanism was attributed to high voltage devices only. However, the results of accelerated nucleon radiation tests made it clear that cosmic radiation-induced breakdown can no longer be disregarded for the design of power devices of voltages classes as low as 500V. Extensive device simulations supported by ion irradiation experiments gave quantitative results and may in the future allow for a predictive assessment of the cosmic radiation hardness of a specific device design.