Low cycle fatigue (LCF) tests for 95.5Sn-3.8Ag-0.7Cu and 99.3Sn-0.7Cu Pb-free solders were conducted for two conditions of 25 degreesC at 1 Hz and 125 degreesC at 0.001Hz. The effect of higher temperature and slower frequency reduces low cycle fatigue endurance. Low cycle fatigue models for 95.5Sn-3.8Ag-0.7Cu and 99.3Sn-0.7Cu Pb-free solders are presented in Coffin-Manson and Morrow models. Comparison with reported Pb-free solder low cycle fatigue properties provides an evaluation of the relative fatigue endurance of Pb-free and Pb-based solders. (C) 2004 Elsevier B.V. All rights reserved.