Effect of nano-Fe2O3 additions on wettability and interfacial intermetallic growth of low-Ag content Sn–Ag–Cu solders on Cu substrates

Abstract

In the present study, Fe2O3 nanoparticles were synthesized and smelted with pure Sn, Ag, and Cu to prepare Sn–1.0Ag–0.7Cu–xFe2O3 nano-composite solders. The content of Fe2O3 nanoparticles ranged from 0 to 1wt.% in the solders. The influences of Fe2O3 nanoparticles on the wettability and the morphology of interfacial intermetallics compounds (IMCs) of low-Ag Sn–Ag–Cu solders on Cu substrate were investigated. Results show that added Fe2O3 nanoparticles can remarkably improve the wettability of Sn–1.0Ag–0.7Cu solder alloys and inhibit the formation and the growth of the interfacial IMCs between the nano-composite solders and Cu substrate. Meanwhile, not only the wettability of the nano-composite solders but also the formation and the growth of the interfacial IMCs, during reflow and aging, are identically relied on Fe2O3 weight percent in nano-composite solders. The enhancement of wettability improvement and interfacial IMC inhibition caused by nano-Fe2O3 addition increased with the addition amount under small concentration. However, excessive addition of Fe2O3 nanoparticles in the Sn–1.0Ag–0.7Cu solder alloys will degrade the wettability and the inhibition effect on the interfacial IMCs. There is an optimum amount of Fe2O3 nanoparticles in Sn–1.0Ag–0.7Cu solder alloys, which is 0.4wt.%, and Sn–1.0Ag–0.7Cu–0.4Fe2O3 solders possess the best wettability and the inhibition effect on the interfacial IMCs formation and growth. The reason for improving wettability and simultaneously inhibiting IMCs formation and growth due to Fe2O3 nanoparticles addition is explained.