The effects of precipitation strengthening and solid solution strengthening on strain rate sensitivity of lead-free solders: Review

Electronic devices are increasingly portable, and often susceptible to damage during handling, transportation, and service. Because of the great variety of stresses to which solder joints are subjected, the mechanical properties of the solder need to be evaluated under a wide range of conditions. The strain rate sensitivity is an essential parameter in understanding the mechanical behaviour of lead-free soldered joints in microelectronics. This literature review is focused on the strain rate sensitivities of lead-free solders and how they are influenced by strengthening mechanisms, including precipitation and solid solution strengthening. Most of the tensile tests and microstructure analysis reviewed showed the dependence of strength on strain rate. However, a clear relationship between solid solution hardening or precipitation hardening and strain rate sensitivity was not revealed in the existing literature.