The creep models of Sn/3.0Ag/0.5Cu solder material under tensile and shear loads are investigated in this study. The creep test results for Sn/3.0Ag/0.5Cu solder material with four operating temperatures, i.e. 120o, 135 o, 150 o and 165 oC are presented. The experimental results reveal that different creep equations are derived for the Sn/3.0Ag/0.5Cu solder material under tensile and shear loadings. The creep parameters, i.e. stress exponent, material constant and activation energy are curve fitted for the tensile and shear loading tests. The concept of failure toughness of solder ball joints is proposed and studied. The effects of high temperature aging and the thermal cycling loading on the failure toughness of different solder materials and ball sizes have also been explored. The difference between failure toughness values of traditional Sn/37Pb eutectic solder ball joints and the lead free Sn/3.0Ag/0.5Cu solder are compared and discussed. The results simulated from finite element method and experiment measurements under the ball shear test (BST) have been compared and studied. The variation stress, strain distributions and failure toughness during the ball shear testing are studied. The fracture behaviors of different ball joints under the high temperature aging and thermal cycles testing are examined and studied. The ball shear test results measured for the same size Sn/37Pb and Sn/3.0Ag/0.5Cu solder ball joints reveal different load-displacement variations. The relative ductility results are measured for the joint of Sn/37Pb solder ball. However, a high peak load and larger deformation are measured for Sn/3.0Ag/0.5Cu solder ball joints. Based on the definition of failure toughness proposed in this study, the higher failure toughness values are observed for the same size lead free Sn/3.0Ag/0.5Cu solder joints. The variation of failure toughness of different ball joints reveals that the high temperature aging and thermal cyclic loading reduce the failure toughness significantly. However, the measured failure toughness values indicate that the Sn/3.0Ag/0.5Cu solder joints have better ductility for the joints undergoing the high temperature aging and the thermal cycle loadings. Based on the measured results, the better reliability for the Sn/3.0Ag/0.5Cu ball joints is expected, due to the aging and cycling load testing.