The HiPak power semiconductor module series is designed for reliable operation under demanding conditions throughout the module’s lifetime. The operation conditions and thus the expected module’s lifetime strongly depends on the application. In operation, the modules are subjected to a variety of temperature profiles, which cause cyclic thermo-mechanical stress in all components and joints of the modules and finally lead to device failure. The magnitude and frequency of these stress-cycles define the lifetime expectancy. Each specific profile leads to different stress distribution throughout the module, so that the weakest link of the module, which finally leads to failure, can be found in different components or joints. Moreover it is not possible to calculate the exact lifetime of individual modules. Instead the lifetime must be expressed in terms of the B10 lifetime, which is the number of cycles during which 10 percent of the total number of modules fails. The aim of this application note is to provide load cycling lifetime data for the power electronics designer to estimate the module lifetime for optimisation of the particular application.