Investigation of Material Dynamic Processes During Shear Test of Aluminum Heavy Wire Bond Contacts

Aluminum heavy wire bonding is still the main technology for conducting power electronic components and modules as well as housing connectors. The standard method for testing the bond quality of heavy wire contacts is the well-established shear test. Criteria of deciding about good or non-good are based on high-purity aluminum wire which is sufficiently used since many years. But in the last decade several developments in terms of the wire materials were forced to improve the properties against harsh environments with e.g. power cycling, alternating thermal impact and vibration fatigue. The general workability and the increased reliability are confirmed by electronics manufacturers. But accompanied by the wire material modification also the mechanical properties are changed. Thus, the shear test results are changing as well, in particular the shear mode can deviate from the expected characteristic of a good bonded contact. So often questions and doubts are appearing regarding the applicability and compatibility of the shear test criteria. For correlating the new developed wire materials and the changed shear test results it is necessary to get a deeply understanding of the mechanisms during the shear test.