中文摘要：

采用纳米压入法对SnG3.0AgG0.5Cu、SnG0.7Cu及SnG3.5Ag无铅焊料的室温应变率敏感性进行研究.相同压深下,压入载荷随着加载应变率的提高而增大;3种焊料的接触刚度均随压深近似线性增加,不同应变率下弹性模量基本不变;硬度随着应变率的增加而增大,表明了无铅焊料的塑性应变率强化性.保载阶段蠕变位移随加载段应变率的增加而增大,蠕变应变率先急剧下降然后趋于稳定.通过系统研究应变率对3种常用无铅焊料力学性能的影响,为评价无铅焊点的服役可靠性提供参考.

英文摘要：

Nanoindentation tests were conducted on lead-free solders of Sn-3.0Ag-0.5Cu,Sn-0.7Cu and Sn-3.5Ag to investigate the strain rate sensitivity at room temperature.For the lead-free solders,indentation load under the same indentation depth increases with increasing loading strain rate.The contact stiffness during loading in-creases with indentation depth approximatively linearly,and the elastic modulus of the lead-free solders under different strain rates basically remains unchanged.The hardness increases as strain rate increases,indicating the strain rate hardening effect of viscous solders.During the holding stage,creep displacement increases with in-creasing strain rate during loading,while the creep strain rate firstly declines sharply and then stabilizes.Effects of stain rate on the mechanical properties of lead-free solders was systematically studied,providing valuable in-formation for the reliability evaluation of lead-free solder j oints in the service process.