High strain rate stress-strain measurement of SAC105 leadfree alloy at temperatures up to 200°C

Material data on properties at elevated temperatures and high strain rates is scarce. There is lack of material models that capture the mechanical deformation under transient dynamic loads at elevated temperatures. Electronics in downhole drilling, automotive and aerospace applications may often be exposed to high temperature during storage, operation and handling in addition to high strain rate transient dynamic loads. Strain rates in the neighborhood of 1–100 per sec may be encountered during operation. Anand Viscoplasiticity models which have been widely used for modeling of material behavior of solder alloys require nine-constants to describe material constitutive behavior. Prior published data on Anand Constants for SAC leadfree solder alloys is limited to either low strain rates or lower temperatures in the neighborhood of 125°C. In this study, mechanical properties of lead free SAC105 has been measured for strain rates 1–100 per sec at elevated temperatures higher than 125°C. Stress-Strain curves have been plotted over a wide range of strain rates and temperatures for pristine specimen which have been fabricated using reflow profiles representative of solder-joint production assemblies. The fabricated SAC105 leadfree alloys specimen have been tested at strain rates of 10, 35, 50 and 75 per sec at various operating temperatures including 150°C, 175°C, and 200°C. Experimental data for the specimen has been fit to the Anand's viscoplastic model. Furthermore, the Anand Model has been used to model the uniaxial tensile test and predict the stress-strain behavior of the solder alloys at elevated temperature. The comparison of the model predictions with the experimental data indicates that the model constants capture the non-linear material behavior for the SAC105 solder alloy accurately.