Natural and Accelerated Aging Effect on Tin-Lead-Antimony Solder Microstructure and Mechanical Properties
Rebecca Wheeling, Don Susan, Shelley Williams
Sandia National Laboratories, Albuquerque, New Mexico, USA
“Sandia National Laboratories is a multimission laboratory managed and operated by National Technology & Engineering Solutions of Sandia, LLC, a wholly owned subsidiary of Honeywell International Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525.”
A solder aging study was performed to understand both the short-term and long-term aging effects on mechanical properties of tin-lead-antimony (Sn-Pb-Sb) solder. Bulk solder samples were aged up to 365 days at five temperatures between room temperature and 135 °C. Microhardness and compression stress-strain tests were performed to understand the mechanical response to aging. Optical and scanning electron microscopy was also performed to evaluate the microstructural impact of aging and relate it to mechanical performance. A reduction in hardness and yield stress values were realized in the first 20-30 days of aging but stabilized beyond 30 days. The accelerated aging results indicate that mechanical properties will continue to decrease over the lifetime of a solder joint, but only to a minor extent.