Effect of Aging and Thermal Shock on the Reliability of Silver Sintered Die Attach for SiC Power Devices

The effect of aging and thermal shock on the reliability of SiC/pure Ag/directly bond copper (DBC) sintered joint fabricated with an assist pressure of 20 MPa was investigated in this study, in which the DBC with the crack-less and deformation-resistant surface finish, i.e., electroplated Ni/electroless Ni-/Pt-/Ag- layers (E-ENPA), was applied. The results showed that the microstructure degraded with increasing aging time and thermal shock cycle. The shear strength of the sintered joint remained above 72.9 MPa after aging at 300 C̊ for 1000 h, and it was no less than 33.5 MPa after 1000 cycles between ‒50 to 250 C̊ . Moreover, the ductility indicated by the fracture pattern remained in an acceptable level. These all suggest the superiority of the novel surface finish of E-ENPA in die attach for SiC power devices.