A double-sided 1200-V/600-A multichip half-bridge insulated gate bipolar transistor (IGBT) module was fabricated utilizing molybdenum as stress-relief buffer and sintered nanosilver as die-attachment. By using the double-sided packaging, the volume, parasitic inductance, and junction temperature were decreased significantly, thus the higher power density could be achieved. However, the thermo-mechanical stress was also increased. In this study, molybdenum instead of the most common copper was used as stress-relief buffer between chips and substrate, thus the thermo-mechanical stress decreased greatly without significant increasing junction temperature. Specifically, by using molybdenum instead of copper as buffer material, the simulation results showed that the IGBT junction temperature at total power loss of 200 W only increased by 5.2% (2.22°C) but the corresponding thermo-mechanical stress decreased by 9.8% (5.58 MPa), and the sintering residual stress decreased by 20.1% (48.88 MPa). Thermal performance, static and dynamic electrical performance, and reliability via power cycling test of the doublesided module were also characterized experimentally. No degradation of the power devices proved that the way to doublesided packaging power devices could be used for future manufacturing of high power density power module.

Recently, to accurately study the transient thermal behavior of power modules, a transient thermal measurement system was developed to investigate the transient thermal behavior of insulated-gate bipolar transistor (IGBT) modules attached by nanosilver paste and two kinds of lead-free solders. We found that the transient thermal impedance of IGBT modules attached by nanosilver paste was 9% lower than that of the modules using SAC305 and SN100C with 40-ms heating pulse. In addition, finite-element analysis is employed to simulate thermal performance of the IGBT devices. The simulation shows that the transient thermal impedance of IGBT modules attached by nanosilver paste was also lower than that of the modules using lead-free solders. A convenient way was introduced to well predict the transient thermal behavior of IGBT power module. The calculated results agreed well with the measured one. The interface thermal impedance of sintered nanosilver and SNC100C are calculated to be 0.011 ~ 0.031 K/W and 0.022 ~ 0.042 K/W, respectively.