Effect of Elevated Storage Temperature on the High Strain Rate Mechanical Properties of SAC305 Solder

Abstract

In the industries like oil/gas exploration, military applications and in automotive applications, the electronic parts can be exposed to high strain rates when affected to vibration, impact, shock and high temperature, as well. In the harsh surrounding, electronic components may experience strain rates of 1 to 100 per seconds and environmental temperature up to 200°C. The records available for lead-free solder alloys at high aging temperature and at high strain rates are not sufficient. Previous published and available records on Anand Constants for SAC305 lead-free solder alloys is restricted to either low strain rates or lesser storage temperatures in the region of 50°C. For the material SAC305, data are not available for the storage at high temperatures. In this paper, lead-free solder alloy SAC305 has been tested and analyzed at various surrounding temperature starting from 25°C up to 200°C, with high strain rates and high aging temperature. After specimen preparation and reflowing, the specimens were stored at 100°C for the period of 1 month and 2 months for the aging, before performing tensile tests at high strain rates at multiple operating temperatures. Stress-strain curves are plotted for the wide range of strain rates and operating temperatures for aged specimen for 1 month and two months, which have been made using reflow profiles illustrative of solder-joint manufacturing assemblies. The prepared SAC305 lead-free alloy specimen aged at 100°C, 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. The calculated experimental data has been fit to the Anand Viscoplasticity model for SAC305 and the Anand constants are established by forecasting the measured stress-strain behavior for the wide range of temperatures and strain rates, at high aging temperature.