The purpose of this paper is to investigate the relationship between microstructure and varied strain rates towards the mechanical properties and deformation behaviour of Sn-3.0Ag-0.5Cu (SAC305) lead-free solder wire at room temperature.
Tensile tests with different strain rates of 1.5 × 10−6, 1.5 × 10−5, 1.5 × 10−4, 1.5 × 10−3, 1.5 × 10−2 and 1.5 × 10−1 s−1 at room temperature of 25°C were carried out on lead-free Sn-3.0Ag-0.5Cu (SAC305) solder wire. Stress-strain curves and mechanical properties such as yield strength, ultimate tensile strength and elongation were determined from the tensile tests. A microstructure analysis was performed by measuring the average grain size and the aspect ratio of the grains.
It was observed that higher strain rates showed pronounced dynamic recrystallization on the stress-strain curve. The increase in the strain rates also decreased the grain size of the SAC305 solder wire. It was found that higher strain rates had a pronounced effect on changing the deformation or shape of the grain in a longitudinal direction. An increase in the strain rates increased the tensile strength and ductility of the SAC solder wire. The primary deformation mechanism for strain rates below 1.5 × 10−1 s−1 was grain boundary sliding, whereas the deformation mechanism for strain rates of 1.5 × 10−1 s−1 was diffusional creep.
Most of the studies regarding the deformation behaviour of lead-free solder usually consider the effect of the elevated temperature. For the current analysis, the effect of the temperature is kept constant at room temperature to analyze the deformation of lead-free solder wire solely because of changes of strain rates, and this is the originality of this paper.
