Reliability Modelling for Different Wire Bonding Technologies based on FEA and Nano-Indentation

Silver sintering technology has been introduced as a replacement for the traditional interconnect technology such as soldering on power modules. Solder fatigue and wire bond failures are two major factors that affects the lifetime of power modules. The silver sinter interconnect technology resolves the lifetime issues of conventional solder fatigue. The wire bond degradation is another factor, which limits the lifetime of the power modules. The researches are going on to reduce the curbs of wire bond degradation. The replacement of Aluminium wire bond by CucorAl or Cu-wire bond can be an approach to increase the lifetime of wire bonds in the power modules. In the project SINTER, some aspects of reliability modeling of silver sintered power stacks with different substrate and wire bonding technologies are addressed. In pressure sintered power stacks, the failure mechanism "wire-bond lift-off" is dominating as long as aluminum heavy wire bonds are used. Thermo-mechanical FEA analysis of different wire bond is conducted on PCB and DCB substrates with a passive thermal cyclic load from (TS -40°C/140°C). The major challenge was the extraction of the material characteristics of CucorAl wire bond. The characteristics of the CucorAl wire has been obtained by Nano indentation. Replacement by CucorAl wires can enhance the bonds lifetime without severe changes in metallization and bonding technology. Modeling of standard aluminum wire bonds reliability versus that of CucorAl wire bonds are the subjects of the paper.