Effect of storage on high strain rate mechanical properties of SAC105 at operating temperature up to 200°C

Electronic devices used in higher temperatures environments such as well logging in the oil and natural gas industries, under hood automotive applications, military applications may be exposed to very high temperatures around 200°C and high strain rates. Previously, lead based solder alloys have been used in such applications but due to health concern, use of lead-free solder alloys (SAC) has been increased. High temperature shock and vibration loads may be generally in the strain rate range of 1–100 per sec. Temperatures in drilling wells can exceed 200°C. Lead free solder material properties may keep evolving when they exposed to thermal aging or high temperatures. There are no published data for effect of aging of SAC105 leadfree solder alloy at high strain rate at very high operating temperature (150°C-200°C). For better design, reliability and process optimization, we need more reliable, consistent solder constitutive equations and material properties. Previously, Materials properties for SAC solder alloys at different strain rates and temperatures have been reported by many researchers. Mechanical properties for SAC solder alloys at operating temperatures up to 125°C and high strain rates (1075 per sec) have been reported by Lall for aged and unaged solder [1-9]. Many constitutive models have been used to represent the material behavior for SAC solder alloys. Anand constitutive model is widely used to describe the deformation behavior for SAC solder alloys as well as Sn-Pb based solder. Anand parameters have been computed for SAC105 and SAC305 for high strain rate and elevated temperature [4-9]. However, there is no prior reported measurement of anand parameters for SAC105 solders during operation at 200°C, at high strain rate. In this study, mechanical properties and constitutive behavior of lead free SAC105 has been measured for high strain rate (10–75 per sec) at elevated temperature (25°C–200°C) for thermal aged samples.