A Study on the Failure Evolution to Short Circuit of Nanosilver Sintered Press-Pack IGBT

In order to improve the heat dissipation capability of high-power press-pack insulated gate bipolar transistor (PP-IGBT), the nanosilver paste was utilized to package a single 3.3-kV/50-A PP-IGBT chip; we called it sintered pack IGBT (SP-IGBT) in this letter and revealed the reliability of such a device based on a power cycling test (PCT). The test results show that the ON-state voltage (Vce) of SP-IGBT sharply increased to 9.5 V after 5500 cycles, and then the device emerged with a special short-circuit failure. The huge heat generated at the moment of device failure caused the sintered nanosilver layer to melt and then squeezed it out by the external pressure, and the melt silver paste directly connected the collector molybdenum layer to the emitter of SP-IGBT die, which is different from the short-circuit failure of fully PP-IGBT due to being electrically broken down. The failed device is analyzed by scanning electron microscope (SEM) and energy dispersive spectrometer (EDS), the failure mechanism is explained by a finite-element analysis, and such work is helpful for the package crafts improvement on the press-pack power modules.