Reliability Analysis of Bond Buffer Technologies for Wide Bandgap Power Devices

Wide bandgap power devices with excellent performance over traditional silicon power devices have been introduced as the prime candidate for power electronics applications. However, interconnections on the chip topside in the traditional packaging are now limiting the lifetime of wide bandgap power devices. It is necessary to replace aluminum bond wires with copper bond wires, ribbons, and lead-frames with the help of bond buffer technologies to ful fill the requirements of wide bandgap power devices under high temperature operation conditions. The reliability performances of different bond buffer technologies and bonding materials under power cylcing tests were reviewed. The Cu-Invar-Cu bond buffer combined with Cu bonding material showed the most robust power cycling capability among all bonding materials. Failure analysus shows that the weak point of the packaging of wide bandgap power devices has been changed from the bonding material to the Al₂O₃ ceramic substrate or the aluminum metallization layer of the chip.