Enhancement and Mechanism of Copper Nanoparticle Sintering in Activated Formic Acid Atmosphere at Low Temperature

Abstract

Cu nanoparticle paste has become one of the alternative materials for conventional high-temperature packaging, but this sintering process is significantly inhibited by copper oxides. In this paper, the activated formic acid atmosphere was used to achieve high-strength Cu–Cu bonding at low temperature. When sintered at a temperature of 275 °C for 30 min with a pressure of 5 MPa, a shear strength of more than 70 MPa was achieved. In contrast to formic acid atmosphere, the hydrogen radicals generated by activated formic acid atmosphere facilitated the rapid evaporation of the solvent during preheating process. Moreover, the hydrogen radicals effectively reduced of the oxides on the surface of the Cu nanoparticle resulting in a higher shear strength. This Cu nanoparticle sintering method has great potential in the field of power device integration in future.

Low-Temperature Sintering of Ag Composite Pastes with Different Metal Organic Decomposition Additions

“…Recent advances in power electronics, including spacecraft, renewable energy vehicles, and high-speed trains, have propelled the demand for electronic packaging towards smaller, faster, and more efficient designs that are suitable for use in harsh conditions. The applications of wide-bandgap (WBG) semiconductors, such as SiC and GaN, continue to expand due to their advanced properties in severe conditions, typically involving temperatures of around 250 °C [ 4 , 5 ]. Consequently, there is a need for die-attach materials that can endure long periods of exposure to temperatures close to or even exceeding 250 °C.…”