Detection of Bond Wire Lift Off in IGBT Power Modules Using Ultrasound Resonators

IGBT modules are one of the key elements in power converters. When electrical stress and environmental factors such as temperature, humidity, vibration, and so on are subjected to large IGBT modules, natural degradation takes place, and cracks are formed in bond wire itself and in Si surface where bond wires are attached to the die. These cracks and lift-offs eventually degrade the device performance leading to a complete failure. This paper introduces a novel approach to detect these failures using inexpensive onboard ultrasound resonators. Experimental results demonstrate that the data generated from the ultrasound resonators could be successfully used to detect the bond wire lift off incidents and associated aging inside the IGBT modules. Therefore, the proposed technique could be considered as a suitable and direct approach to characterize IGBT aging, where the results do not depend upon the operating point (voltage and current levels) of the IGBT.