Research on Long-term Reliability of Silver Sintered Press-Pack IGBT Modules

Abstract

Owing to the advantages of short-circuit failure mode, double-sided heat dissipation, and low thermal resistance, press-pack insulated gate bipolar transistors (PP-IGBTs) are widely used in high-power-density applications, such as high-voltage direct-current converters. As the core device of large-capacity power equipment, the reliability of a PP-IGBT is directly related to the security of the power system. In recent years, a silver-sintered package has been proposed to improve the electro-thermal performance of PP-IGBTs. However, the long-term reliability of this package has not been proven. In response to this problem, 3300-V/50-A silver-sintered PP-IGBT (SPP-IGBT) modules are used in long-reliability research. First, electro-thermal-stress finite-element models of PP-IGBTs and SPP-IGBTs were proposed and the accuracy of models verified by experiments. Through a simulation comparison, the results show that under the rated operating conditions, the on-voltage and maximum temperature of SPP-IGBTs dropped by 9.3% and 3.7%, respectively. In addition, the temperature and stress of each component were reduced, among which the surface stress of the IGBT chip emitter dropped by as much as 24.7%. Subsequently, a power-cycle test platform was established, and three PP-IGBTs and three SPP-IGBTs were tested. Finally, the experimental results were compared and analyzed, and the reasons for the sharp increase of on-voltage and metal melt were explored. The results show that the silver-sintered package improves the electrical-thermal performance and long-term reliability of the module. • Electro-thermal-stress finite-element models of PP-IGBT and SPP-IGBT were established separately. The accuracy of the model is verified by the temperature in the experiment, and the error is less than 5%. • Electrical, thermal, and stress indexes of PP-IGBTs and SPP-IGBTs were analyzed and compared. The on-voltage, maximum temperature and IGBT chip emitter surface stress of SPP-IGBTs dropped by 9.3%, 3.7% and 24.7%, respectively. • Three PP-IGBTs and three SPP-IGBTs were used for power-cycle test under same condition. The results also show that the SPP-IGBT has better electro-thermal performance, less surface wear of the chip emitter, and better long-term reliability.