High Temperature Creep Properties of Sn-3.5Ag and Sn-5Sb Lead-free Solder Alloys

摘要

In order to acquire relevant creep characteristics such as stress exponent and activation energy, creep strain tests were conducted on Sn-3.5Ag and Sn-5Sh systems of solder alloys in the intermediate temperature regime from 353 K to 453 K corresponding to the homologous temperatures η =0.715 ~0.917 and η =0.699 ~0.897 for the two alloys, respectively. It was found that an apparent creep-activation energy of both Sn-3.5Ag and Sn-5Sb solder alloys had a change point at η =0.82 under the higher stress of 9.8 MPa. At the lower stress of 4 MPa. the change point was found only for Sn-5Sb alloy. Moreover, under the lower stress level, the stress exponent of both solder alloys are approximately 1, while under the higher stress region (more than 9.8 MPa), the stress exponents of both solders are 7 or more. Determining factors of creep deformation are discussed in relation to the temperature and stress region. It was considered that the deformation of both solder alloys is dominated by the rate of the dislocation climb/dislocation glide in the higher temperature and stress region.