Effect of 100°C Aging for Periods of up to 120-days on High Strain Rate Properties of SAC305 Alloys

Abstract

In the applications like automotive, military applications and in oil/gas exploration, the electronic parts can be exposed to vibrations, impact, shocks and high temperatures, as well. In these harsh environments, electronic components may experience strain rates of 1 to 100 per seconds and environmental temperature up to 200°C. The published literature available for lead-free solder alloys at high aging temperature and at high strain rates is scarce. Previous published and available studies for SAC305 lead-free solder alloys are restricted to either low strain rates or lower storage temperatures in the region of 50°C. High temperature, high strain-rate properties of SAC305 are not available for prolonged periods of isothermal storage. In this paper, lead- free solder alloy SAC305 has been tested and examined at numerous surrounding temperatures from 25°C up to 200°C, with high strain rates and elevated thermal aging temperature. The specimens were stored at 100°C for the duration of 3 months and 4 months for thermal aging. These thermally aged SAC305 lead-free solder specimen, which have been made using reflow profiles indicative of solder-joint manufacturing assemblies, have been tested at strain rates of 10, 35, 50, and 75 per sec at multiple operating temperatures ranging from 25°C to 200°C. Stress-strain curves are prepared for the wide range of operating temperatures and strain rates for thermally aged specimens for 3 months and 4 months durations. The experimental results have been fit to the Anand Viscoplastic model for SAC305 and the Anand constants are established by estimating the measured stress-strain behavior for the wide range of temperatures and strain rates, after high temperature storage of specimens.