Effect of Property Evolution of Doped and Undoped SnAgCu Solder Alloys Under Shock and Vibration

Abstract

Electronics may be required to operate in harsh environments in automotive, aerospace, and defense applications. Solder interconnects in harsh environments may be subjected to extremely-low and high temperatures in the range of −65C to +200C in conjunction with significant strain loads. Furthermore, electronic assemblies may be subjected to extended periods of non-climate-controlled storage prior to deployment. Prior studies have shown that lead-free solder materials continue to evolve under varied thermal loads, leading to deterioration in mechanical parameters such as Ultimate Tensile Strength and Elastic Modulus. The material characteristics for non-linear modeling and reliability prediction are required for risk minimization with the use of new alloy formulations in high-reliability applications. The current work fills this state-of-the-art gap by measuring the mechanical characteristics of undoped SAC105 and doped SAC-Q solder alloys at low operation temperatures (−65°C to 0°C) at high strain rate after varied thermal aging periods up to one year. In addition, the evolution of Anand parameters for SAC solder alloys after prolonged thermal aging has been studied. The Anand model’s reliability has been assessed by comparing experimentally observed data with forecasted data using determined model constants for both solder alloys. The Anand parameters were applied in a FE-framework to simulate drop events for a ball-grid array package on a printed circuit board assembly.