To prevent the power electronics from failing, engineers have played it safe to date by using more semiconductor modules than are necessarily required. The larger the semiconductor surface, the better the temperature balance. However, this solution is similar to the image of the concrete dome as a house roof. “Oversized power electronics are not optimal when it comes to installation space and costs,” says Marco Denk, head of Advanced Engineering Power Electronics in the ZF E-Mobility Division. Since engineers always like to find the optimum solution, Denk asked himself the following question: How can temperature fluctuations and their impact on the service life of a semiconductor be more precisely determined? If we knew the answer, then only as many of those expensive modules as truly needed would have to be installed for the service life of a vehicle, including safety reserves.