Influence of doping Si 3 N 4 nanoparticles on the properties and microstructure of Sn58Bi solder for connecting Cu substrate

Purpose This study aims to explore the feasibility of adding Si 3 N 4 nanoparticles to Sn58Bi and provides a theoretical basis for designing and applying new lead-free solder materials for the electronic packaging industry. Design/methodology/approach In this paper, Sn58Bi- x Si 3 N 4 (x = 0, 0.2, 0.4, 0.6, 0.8, 1.0 Wt.%) was prepared for bonding Cu substrate, and the changes in thermal properties, wettability, microstructure, interfacial intermetallic compound and mechanical properties of the composite solder were systematically studied. Findings The experiment results demonstrate that including Si 3 N 4 nanoparticles does not significantly impact the melting point of Sn58Bi solder, and the undercooling degree of solder only fluctuates slightly. The molten solder spreading area reached a maximum of 96.17 mm 2 , raised by 19.41% relative to those without Si 3 N 4 , and the wetting angle was the smallest at 0.6 Wt.% of Si 3 N 4 , with a minimum value of 8.35°. When the Si 3 N 4 nanoparticles reach 0.6 Wt.%, the solder joint microstructure is significantly refined. Appropriately adding Si 3 N 4 nanoparticles will slightly increase the solder alloy hardness. When the concentration of Si 3 N 4 reaches 0.6 Wt.%, the joints shear strength reached 45.30 MPa, representing a 49.85% increase compared to those without additives. A thorough examination indicates that legitimately incorporating Si 3 N 4 nanoparticles into Sn58Bi solder can enhance its synthetical performance, and 0.6 Wt.% is the best addition amount in our test setting. Originality/value In this paper, Si 3 N 4 nanoparticles were incorporated into Sn58Bi solder, and the effects of different contents of Si 3 N 4 nanoparticles on Sn58Bi solder were investigated from various aspects.