Reliability Degradation of SAC105 and SAC305 BGA Packages Under Long-Term, High Temperature Aging
Authors: Zhou Hai, Jiawei Zhang, Chaobo Shen, E. K. Snipes, J. C. Suhling, M. J. Bozack and J. L. Evans Company: Auburn University Date Published: 4/1/2014
Abstract: The thermal cycling performance of Pb-free (SAC105 and 305) fine-pitch BGA packages degrades up to 61% after 2 years of aging at high temperatures. The test array ranged from 19mm, 0.8mm pitch ball grid arrays (BGAs) to 5mm, 0.4mm pitch µBGAs; 0.65mm MLF and 2512 resistors. The isothermal aging temperatures were 25°C, 55°C, 85°C and 125°C over time periods of 0, 6, 12, and 24 months. The thermal cycling profile was from -40°C to 125°C with 15 min dwell times at the high and low peak temperatures. Weibull tracking and the associated thermal-mechanical (microstructural) response are reported. The dominant failure mode is associated with cracks that run along the growing Cu6Sn5 and Ag3Sn phases that develop during aging and subsequent cycling.