Elevated-temperature shear creep evolution and life prediction of sintered nano-silver lap-shear joint

Nano-silver paste, as a state-of-the-art die-attach material, has great application potential on elevated temperature, high power wide-band semiconductor packaging. During operation of semiconductor devices, sintered nano-silver bond-lines have to withstand creep deformation caused by elevated operating temperature and high switch frequency. In this study, the shear creep behavior of nano-silver sintered lap-shear joint was studied over the shear stress range from 3.5 to 8 MPa and the elevated temperature range from 498 to 598 K. Four kinds of constitute equations, namely three-parameter theta projection concept, Kachanov damage evolution, Larson-Miller parameter relationship and Monkman-Grant relationship, were employed to describe the shear creep behavior and predict the shear creep rupture life of the joint. For nano-silver sintered lap-shear joint, the three-parameter theta projection could quantitatively describe the shape of individual creep curves at any specified stress and temperature. The creep damage evolution of the joint, which was investigated by Kachanov damage evolution, was temperature dependent. The prediction accuracy of creep rupture life using these four kinds of constitutive equations was also evaluated.