Anti-Oxidation Sintering of Ag-10Cu Composite Paste on DBC Substrate in Air Atmosphere

To address the oxidation issue of sintered AgCu/DBC joints during air atmosphere in wide bandgap semiconductor devices packaging, in this study, a synergistic strategy integrating material and process design was proposed. By introducing ascorbic acid (AA) into the solvent system and employing a rapid sintering process, an oxidation-resistant Ag10-Cu composite solder paste was successfully developed. Experimental results show that the sintered Ag-10Cu paste containing AA achieved the shear strength of 43.8 MPa after 5 min sintering process in air atmosphere, significantly exceeding the MIL-STD-883K standard (7.8 MPa). Fracture occurred at the sintered layer/DBC interface. Microstructural analysis revealed that no copper oxides were observed at the interface, and AA was found to effectively reduce surface oxides on the Cu particles. This technique, based on the synergistic effect of a reducing agent and rapid sintering, effectively addresses Cu oxidation during air sintering and provides a low-cost, high-reliability interconnection solution for high-power devices packaging.