Degradation of Heavy Wire Bond Interfaces

The recent improvements in power module reliability by using the low temperature joining technique for the die attach and substituting the base plate and its solder technology by a pressure contact design have led to a situation in which the reliability of the wire bond is now the main lifetime determining factor [1, 2, 3]. In order to extract a lifetime model for the wire bond the degradation process in the interface region between the wire and the power semiconductor during temperature cycling must be studied at single bond level. Module designers and quality engineers are then able to use this lifetime model in combination with electro-thermal simulations of their package to calculate wire bond lifetime in advance.