Effect of nano-Ag_3Sn additions on wettability, interfacial intermetallic growth and mechanical properties of Zn-30Sn-1Ge solders on Cu substrates

摘要

The influences of different addition (0, 0.2, 0.4, 0.6, 0.8, and 1.0 wt%) of Ag_3Sn on the wettability, the morphology of interfacial intermetallic compounds (IMCs), and the mechanical properties of Zn30Sn1Ge (ZSG) solder on Cu substrate were investigated. The Ag_3Sn nanoparticles with an average particle size of approximately 30-45 nm were dispersed in the α-Zn phase and IMC layer. The added Ag_3Sn nanoparticles can remarkably improve the wettability of ZSG solder and inhibit the formation and growth of the interfacial IMCs between the nanocomposite solders and Cu substrates. The enhancement of wettability and inhibition of interfacial IMC increased with the increase of nano-Ag_3Sn addition amount under low concentration. However, the excessive addition of Ag_3Sn nanoparticles in ZSG solder will degrade the wettability and inhibition of interfacial IMCs. When the amount of Ag_3Sn nanoparticles is 0.6 wt%, the ZSG-0.6Ag_3Sn solders possess the best wettability. In addition, the ZSG-0.4Ag_3Sn solder exhibits the most prominent effect in retarding the formation and growth of interfacial IMCs. Meanwhile, the addition of Ag_3Sn nanoparticles increases the shear strength and Vickers hardness of the solder joint. When the amount of Ag_3Sn nanoparticles is 0.4 wt%, the shear strength of the welded joint is increased by 13.3%. Moreover, the macroscopic hardness of ZSG-0.6Ag_3Sn solder is 49.507 HV, which is 57.5% higher than that of the solder without added nanoparticles (31.38 HV). Results show that the addition of Ag_3Sn nanoparticles plays an important role in the interfacial reaction and mechanical properties between the ZSG solder and Cu substrate.