A low cost multi-shapes designed sintering composite paste: A strengthening method of sintered interconnect for die attach in high temperature applications

In this work, we proposed a multi-shape designed Ag-Cu bimetallic pastes for die attach sintering in power electronic packaging. We found a good adaptation of Ag flakes and Cu sphere particles in the sintered microstructure of the multi-shapes pastes. Under the "rolling effects" of the Cu particles, Ag flakes become more compact with larger plastic deformation. Further analysis indicates that sintering properties is highly dependent upon the shapes of the particles. The fracture interface is also highly dependent upon particle shape combination in sintering paste. For Ag flake- Cu sphere combination, more residual sintered masses were found at the fracture interface, which indicate a good strength matching of the sintered bulk and the interface. The sintered die attach connection with optimized particle shape combination perform a maximum shear strength up to 47.42 MPa, which is obtained at a much lower cost than normally used Ag paste.