Research on the Bond Wire Lift-Off Failure Mechanism During Power Cycling Aging of IGBT Modules

Bond wire lift-off is a major aging failure mode in Insulated Gate Bipolar Transistor (IGBT) modules, critically impacting their safe and reliable operation. This paper presents power cycling aging experiments on IGBT modules. With increasing power cycles, the IGBT module exhibits a significant rise in both on-state voltage drop and junction temperature, as shown by the results. Disassembly of failed modules revealed that bond wires at the IGBT chip edge exhibited lifting and peeling of the pins. A current-thermal-structural multi-physics coupling model was developed to investigate the mechanism of bond wire lift-off during power cycling. Simulations showed concentrated current density and stress at the pins edges where bond wires, chip surface, and silicone gel meet. Uneven chip surface temperature distribution, due to solder layer aging, stressed the end pins at the module edge, causing initial micro-cracks. Compared to a healthy state, the current and stress fields at the micro-crack increased by 421.4% and 1024.1%, respectively, accelerating crack propagation and leading to complete end pin lift-off. This lift-off further degraded the bonding of other healthy bond wires, ultimately causing module failure. These results provide a reference for IGBT module aging failure analysis and reliability design.