Mechanical Behaviors Of The Lead-free Solder And Constitutive Model

The uniaxial tests and the torsion tests at different strain rates were conducted on the Sn-0.7Cu solder. The tensile strength and saturated stress reduced obviously with the strain rates, and Sn-0.7Cu is rate sensitive material. Cyclic tests under different 15 loading paths were conducted on the Sn-0.7Cu solder including uniaxial, torsional, proportional and non-proportional cyclic loading. With the comparison of the test results, it can be found firstly that the stress amplitudes for the same strain amplitude reduced with the strain rates. The stress amplitudes at the same strain rates followed the Ramberg-Osgood equation. It can also be found that loading history has a great influence on the mechanical properties of the material. Compared with the stress-strain relationship under proportional loading, Sn-0.7Cu has the additional hardening and more cyclic softening under non-proportional loadings. The extent of the hardening and softening are related to the loading paths.Bodner-Partom model is used to simulate the stress-strain relationship of the Sn-0.7Cu solder. The parameters can be decided by tension tests. The comparison between the simulation and the test results shows that the visco-plastic model can reflect rate dependence of the material very well. Moreover, the shape of the hysteresis loop can be simulated well at the non-proportional tests. The Bodner-Partom model can be used in the simulation of the properties of the lead-free solder under complex loading conditions.