Die Attach for High Temperature Electronics Packaging (original) (raw)

AuSi, patterned Au and off-eutectic Sn-Au-Sn die attach materials and processes have been investigated for SiC die attach for high temperature applications. AuSi shear test results after 3000 hours of aging at 325 o C in air showed only a slight decrease in shear strength when assembled on Mo:Mn/Pd/Au metallized AlN. However, when assembled on Mo:Mn/Ni/Au metallized AlN, the die shear strength decreased dramatically after only 500 hours at 325 o C in flowing nitrogen. The patterned Au die attach showed a decrease in shear strength and a change in failure mode after storage at 500 o C in air. The initial failure mode was in the Au bump, but after 500 hours at 500 o C, the failure mode shifted to failure near the SiC die interface. A similar change in failure mode was observed with off-eutectic Sn-Au-Sn die attach stored at 500 o C. In both cases there was evidence of Ti diffusion from the Ti/Ti:W/Au thin film metallization stack on the backside of the SiC die.