Influence of Temperature on Bond Wire Fatigue of Gate Loops in IGBT Modules under Sinusoidal Vibration Stress

The vibration fatigue mechanism in IGBT modules is critical, while experimental data on this topic is still insufficient. In this paper, a vibration-temperature test platform for IGBT modules is developed, and the sinusoidal vibration tests are conducted in the y-axis direction. The location of the vibration-sensitive components is identified by observation after broken fault indicated by static characteristics. It is observed that the bond wires in gate loops are fragile components. Then, high-frequency impedance between the gate- and Kelvin-emitter terminals is proposed as condition monitoring indicator during the vibration test. The impedance can be reflected by the peak voltage of a sampling resistor, which has noticeable variation before the complete disconnection of the bond wire. The beginning of the variation is defined as the failure point, which is much earlier than seen in the static characteristics. Then the number of cycles to failure (NCF) is investigated at various temperatures. The NCF is found to decrease with temperature. Post-failure observations of all tested 48 modules under test are conducted.