A 3-D modle of BGA package is established based on Ansys to investigate the mechanical behavior of solder by different dwell time and ramp time.The thermal cycle lives are calculated and compared according to Darveaux equations.Results demonstrate that solder joint fatigue life is more sensitive to dwell time than ramp time during thermal cycling.Increasing dwell time past 20min has a minimal effect on the lifetime.The focus of temperature cycling tests should not be upon ramp time

but upon dwell time.