Constant Strain-Rate Garofalo Creep Behavior of Intermediate 83Pb/10Sb/5Sn/2Ag and 91.5Sn/8.5Sb Solder Materials

Modern electronics reliability prediction models require materials-specific failure data across a range of conditions. Garofalo models are preferred due to their ability to accurately predict performance over a wide temperature range. However, data on intermediate solders are sparse, especially regarding performance at cold temperatures. We report Garofalo creep data for 83Pb/10Sb/5Sn/2Ag (Indalloy 236) and 91.5Sn/8.5Sb (Indalloy 264). Indalloy 236 exhibits an activation energy of 54.5 kJ/mol, n = 4.5, and alpha = 0.043 while Indalloy 264 exhibits an activation energy of 70.04 kJ/mol, n = 2.705, and alpha = 0.099 from -20 degrees C to 175 degrees C. We show that modern curve-fitting analysis should be utilized for Garofalo analysis rather than traditional linearization methods. X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS) were used to characterize the changes in the alloy phases during testing. Microstructural analysis indicates that Indalloy 236 can experience void coalescence at high temperatures while Indalloy 264 precipitates antimony-rich phases on the grain boundaries.