New Ag pastes siter joining on Ag and Cu surface for high temperature application

New Ag pastes composed of Ag particles with different diameters and shaped were developed as die-attached materials for high power, high frequency and high temperature applications. The composition of the Ag paste with various diameters and shapes contributed to high dense sintered joint, which achieved high thermal conductivity over 200 W/m·K. The Ag paste sintered not only in air but also in N2 environment realized high shear strength. Furthermore, except the Ag-plating Cu substrates, the Ag paste could also be directly connected to bare-Cu substrates without any pressure and gave a shear strength of over 25 MPa at 250°C in N2 environment. The cross-section microstructure clearly indicated that no oxide layer was found between bare-Cu substrates and Ag paste. These results suggest that the new Ag pastes are a promising interconnect material for high performance wide bandgap SiC/GaN devices.