Long-time reliable direct bonding of silver flake paste on Al substrate for power electronic die-attachment

Silver paste is supposed to be a most prospective die-attach material for power electronics. While, the bonding of silver paste with aluminum substrate cannot be easily achieved due to the native oxidation of aluminum. This work provides a direct bonding of aluminum with silver micro flake-based paste under 250℃ with a shear strength of 15 MPa with a propriate surface treatment method of aluminum, and the shear strength even keeps higher than 15 MPa after storing at 250℃for 1000 h. The bonding mechanism was elucidated with high resolution transmission electron microcopy. The results indicate a new route for the wide application of Al based substrate in power electronic with low cost.