Growth mechanism of intermetallic compounds and damping properties of Sn-Ag-Cu-1 wt% nano-ZrO2 composite solders

Nano-sized, nonreacting, noncoarsening ZrO2 ceramic particles reinforced Sn-Ag-Cu composite solders were prepared by mechanically dispersing nano-particles into Sn-Ag-Cu solder and investigated their microstructure, kinetic analysis and mechanical properties i.e., shear strength, hardness and high temperature/mechanical damping characteristics. From microstructures evaluation, it was clear that composite solders containing ZrO2 ceramic nano-particles significantly impact on the formation of intermetallic compounds (IMCs) at their interfaces as well as refined microstructure in the solder ball regions. The growth behavior of IMCs layer at the interfaces in composite solders was lower than that of plain Sn-Ag-Cu solders. Moreover, after long time aging, some microcracks were clearly observed at the interface due to the formation of excessive IMC layer and softening nature of plain Sn-Ag-Cu solder joints. Mechanical properties i.e., shear strength, hardness and high temperature/mechanical damping characteristics were successfully investigated. The experimental results showed that composite solder joints exhibited higher hardness and shear strength as compared to the plain Sn-Ag-Cu solder joints. In addition, composite solder containing ZrO2 nano-particles exhibited lower damping capacity as compared with plain Sn-Ag-Cu solder due to fine microstructure and uniformly distributed ZrO2 nano-particles which increase the dislocation density. (c) 2014 Elsevier Ltd. All rights reserved.