In-situ monitoring of thermo-mechanical induced stresses in electronic control unit – from the assembly to use in the field

The transformation in the automobile sector caused by autonomous driving and new mobility solutions results in a tremendous increase of the typical vehicle service time from about 10000h to more than 50000h [1]. To enable today’s electronics for such challenging usage times, new concepts are necessary to ensure reliable designed electronics over the entire vehicle lifetime.Connected Braking systems brings the development of reliable electronics on a new level, enabling electronic devices with novel sensor for in-situ stress monitoring in real field applications.In this paper we present a novel method of monitoring the internal stresses of ASIC package in a braking systems electronic control unit starting from the development and production process and testing till application in testing car.We developed an electronic control unit (ECU) equipped with a data processing architecture that enables us to read and send out all relevant ECU signals to a data-cloud during field application. On the tested ECU we have placed a piezoresistve stress sensor encapsulated in a QFN type of the package. We recorded the stresses during assembly stages from the bare PCB board until test of the ECU in the car. This allows us to better understand how the assembly steps contribute to the stress state as well as compare the stresses induced during reliability testing and field application. Finally, we discuss how different types of reliability investigations (e.g. on the board and system level) might change the stress condition in the design element, supported by FEM simulation results.