Synthesis and characterization of Sn–Cu/SiO2(np) lead-free nanocomposite solder through angular accumulative extrusion.

This study synthesized Sn-0.7wt.%Cu/Xwt.%SiO₂ nanocomposite solder by angular accumulative extrusion (AAE). AAE is a severe plastic deformation process used here to synthesize a metal matrix composite for the first time. The Sn-0.7wt.%Cu lead-free solder has proved to be an appropriate alternative for Sn–Pb solder due to its lower cost than other lead-free solders, good wetting and electrical conductivity, and high creep resistance. The characterization results showed that adding silica nanoparticles improved the solder properties compared to the monolithic sample. Compared to the monolithic sample, the tensile properties of as-extruded nanocomposite solder samples containing 0.5- and 1-wt% nanoparticles have increased by 22 and 12%, respectively. The joint shear strength of nanocomposite solders increased by 9% and 17%, tensile strength by 41% and 44% and microhardness by 14% and 32% after reflow for the samples containing 0.5 and 1% nanoparticles, compared to the monolithic sample, respectively. Moreover, adding nanosilica particles decreased the wetting angle with a copper substrate, refined the microstructure, and suppressed undesired intermetallic compound formation compared to the monolithic sample. Accordingly, the synthesis of nanocomposite solder by AAE has been successful. [ABSTRACT FROM AUTHOR]