Long-term reliability evaluation of power semiconductor devices used in substation rectifiers

To enable evaluation of the long-term reliability of power semiconductor devices used in commercial substations, this paper presents the failure rate of such devices in practical use. Recovery activation energies are also evaluated on the basis of annealing and bias stress test. Degraded devices are disassembled and examined. In some of them, melting and defects at the silicon chip edge caused a large leakage current. It is also found that the leakage current spectrum is strongly related to breakdown voltage degradation. A novel monitoring method using the leakage current spectrum is proposed here for the first time