Nanoindentation Creep, Elastic Properties, and Shear Strength Correlated with the Structure of Sn-9Zn-0.5nano-Ag Alloy for Advanced Green Electronics

Abstract

This work investigates the influence of an Ag nanoparticle addition on the microstructure, microhardness, creep, temperature-dependent elastic properties, damping capacity, and shear strength of an environmentally friendly eutectic Sn-9Zn (wt.%) material. A microstructure analysis confirmed that adding Ag nanoparticles significantly altered the morphologies of the Zn-rich phase, which includes the size and shape in the presence of fine spherical-shaped AgZn3 intermetallic compound (IMC) particles in the β-Sn matrix. These fine microstructures positively impact on microhardness, creep, damping capacity, and temperature-dependent elastic properties. Furthermore, in the electronic interconnection on an Au/Ni-plated-Cu pad ball grid array (BGA) substrate, adding Ag nanoparticles generates an additional AgZn3 IMC layer at the top surface of the AuZn3 IMC layer. It also significantly improves the oxidation resistance of Sn-Zn material due to the formation of fine AgZn3 IMC particles. Moreover, the interfacial shear strength value of the Sn-Zn material doped with Ag nanoparticles on the Au/Ni-Cu pad BGA substrate increased about 12% as compared to the reference material after five minutes of reaction in the presence of a fine Zn-rich phase and AgZn3 IMC particles, which acted as second phase dispersion strengthening mechanism. Adding Ag nanoparticles also altered the fracture mode to a typical ductile failure with rough dimpled surfaces of the Sn-Zn material.

Keywords

• lead-free green alloy
• microstructure
• creep property
• damping capacity
• shear strength