Development of an In-Line Capable Transient Thermal Analysis Equipment for a Power Module with Five Half Bridges

Transient thermal analysis (TTA) is a widely spread and non-destructive method to qualify the thermal integrity of power electronic modules. Compared to X-ray and acoustic microscopy (SAM), TTA permits a more detailed investigation of the thermal path since the response of the thermal path is the directly measured. However, standard TTA is to time intense for a 100% in-line inspection in the short time slots of production lines, since averaging over multiple measurement repetitions is required to obtain qualitative date with adequate signal to noise ratio (SNR) in the time range 1 µs to 1 ms. For this reason, an advanced pulses sequence with dedicated computation algorithm for TTA measurements was developed to improve SNR without increasing the measurement time significantly. The algorithm allows a SNR increase in the early time range below 1 ms by averaging over short pulses in the sequence. In this paper, a measurement equipment is developed to apply sequence and algorithm on a commercial power module with 10 MOSFETs to verify in-line capability of equipment and algorithm. The data is additional compared to X-ray and SAM.