DIE ATTACHMENT METHOD ON A Cu FINISH BY PRESSURE-ASSISTED SINTER BONDING IN AIR USING Cu FORMATE PASTE

A paste containing Cu(II) formate rods was prepared, and characteristics of sinter bonding at 250 degrees C under a pressure of 10 MPa were investigated to accomplish a high-speed die attachment for wide-bandgap power chips on Cu finish in air. Synthesis of the plate-type Cu formate particles from CuO was accomplished through a wet reaction for 180 min. Cu, formed in situ in the bondline by pyrolysis of the formate during heating for the attachment, was sufficiently active to lead high-speed sintering within a carbon dioxide-hydrogen atmosphere derived from the pyrolysis, and the oxide layer on the Cu finish was reduced by the hydrogen. As a result, sinter bonding for 10 min formed a robust bonding with a shear sliength approaching 27 MPa.