Nickel Nanoparticles Mediated Growth of the Intermetallic Compound between Sn-1.0Ag-Xni Solders Alloy and Cu Substrate

Abstract

In the present study, the effect of addition of Ni nanoparticles on the growth of the intermetallic compound (IMC) layer between low-silver lead-free solder and Cu substrate was investigated. Ni nanoparticles were synthesized and smelted with pure Sn, Ag to prepare Sn-1.0Ag-xNi (x=0, 0.05, 0.1, 0.2) solder alloy. Sn-1.0Ag-xNi was soldered on a copper substrate, and then the solder/Cu couples were isothermally aged at 423K for 360h.The Cross-section images of IMCs layer were obtained to observe the morphology of IMC and to measure the thickness of Cu6Sn5and Cu3Sn layers respectively. The results show that, during aging, addition of Ni can remarkably improve the morphology of IMC, level the scalloped IMC, facilitate the growth of the total interfacial IMCs and inhibit the growth of Cu3Sn. Moreover, the rate change of thickness of the Cu3Sn reduced obviously with the increase of Ni nanoparticles. Comprehensive analysis shows that the addition of Ni promotes the nucleation and growth of Cu6Sn5. The thermodynamics calculation on the solder alloy was identical with the experiment result.