Tin nanoparticles modified nano-silver paste for pressureless low-temperature sintering process

Silver nanoparticles (Ag-NPs) with the average size of 9 nm and tin nanoparticles (Sn-NPs) with the average size of 30 nm were synthesized via chemical reduction in aqueous solutions, respectively. Then, a novel nano-sliver paste modified by tin nanoparticles (NSP-TNP) was developed and the influences of Sn-NPs content, sintering time and temperature on bonding strength of NSP-TNP joints were studied. After sintering the nano-silver paste modified by 3 wt.% Sn-NPs at 206 °C for 30 min without externally applied pressure, the bonding strength of sintered NSP-TNP joints reaches 34 MPa. The enhanced mechanical strength of the sintered NSP-TNP joints is owing to the denser structure and solid-solution strengthening when Sn-NPs were added to the nano-silver paste. The NSP-TNP is promising to be used in power semiconductor (e.g., SiC) packaging due to some advantages such as higher bonding strength, lower processing temperature and reduced cost.