Reliability testing and analysis of IGBT power semiconductor modules

IGBT power semiconductor modules have become of the utmost importance for traction applications. Their control circuitry is of much lower expenditure than those for GTOs. Power converters for tramways, elevators and railway locomotives will be equipped with IGBT modules in the future. However, the reliability of these power modules is still a serious concern, compared to the comparable good reliability of GTO presspack technology. Although first approaches have already been announced, the presspacking of IGBTs is a rather difficult and expensive process, because of the complex IGBT structure and the wafer processing yields in IGBT wafer manufacturing. On the other hand, tough operation conditions in case of traction applications cause reliability requirements which need significant improvements of the present conventional wire bond/die-attach module packaging technology. Reliability tests, which should represent traction operation of modules in the field, show that wire bonding and soldering may cause failures of the modules. The paper presents analysis results and ways of how these problems might be solved.