Approach for reliability of Thermal Interface Materials in battery cell sensors

In battery packs it is important to know, which temperature the cells have, to avoid overloads and damages. A temperature sensor, which is joined on the battery cell, delivers such data. To guarantee exact temperature measurements on the cell, reliable Thermal Interface Materials (TIM) are needed. They ensure heat transfer from battery cell to the sensor and need to provide good thermal conductivity, moisture independence and adhesion performance under combined environmental loads. For these requirements three different TIM materials were tested and analyzed to determine defects and observing degradation processes under cyclic temperature and moisture loads. Also on focus are the selection guidelines of the correct TIM for different application. The paper describes the characterization of different TIMs, new thermal test cycles combined with moisture and the resulting effects on degradation behavior of TIMs.