Thermal Behavior of an Electronics Compartment with Respect to Real Driving Conditions

The reliability of electronic components is of increasing importance for further progress towards automated driving. Thermal aging processes such as electromigration is one factor that can negatively affect the reliability of electronics. The resulting failures depend on the thermal load of the components within the vehicle lifetime - called temperature collective - which is described by the temperature frequency distribution of the components. At present, endurance testing data are used to examine the temperature collective for electronic components in the late development stage. The use of numerical simulation tools within Vehicle Thermal Management (VTM) enables lifetime thermal prediction in the early development stage, but also represents challenges for the current VTM processes [1, 2]. Due to the changing focus from the underhood to numerous electronic compartments in vehicles, the number of simulation models has steadily increased. Standard load cases such as “Slow Uphill Drive” cannot be applied to these models. The definition of new load cases for maximum and lifetime temperatures requires comprehensive analysis of specific compartment boundary conditions. This publication focuses on a specific compartment in the trunk of a Mercedes Benz S-Class. The impacts of environmental and HVAC conditions on the temperature of the electronic components are shown by wind tunnel tests. A numerical Design of Experiments (DoE) is used to determine individual boundary condition effects, such as ambient temperature or the mass flow rate through the compartment. A vehicle endurance test provides an overview of the lifetime temperatures and the corresponding boundary conditions for the electronic components in this compartment. The results show that the boundary conditions are mainly dependent on the ambient temperature.