Resonant vibration behavior of lead-free solders

This study investigated the resonant vibration-fatigue characteristics of some potential lead-free solders, including Sn-Zn, Sn-Ag Sn-Cu, and Sn-Bi alloys. Results show that, under a fixed vibration force, the damping capacity and vibration-fracture resistance of Sn-Cu and Sn-Ag eutectic alloys with an off-eutectic structure are higher than Sn-Pb and are also higher than Sn-Bi and Sn-Zn. This is closely related to the vibration-deformed structure and crack-propagation morphology associated with the microstructural features of the materials. Also, the striated deformation in the Sn-rich phase can be regarded as an effective mechanism in absorbing vibration energy. Moreover, microstructural modification of the Sn-Zn eutectic alloy can be achieved through Ag addition, and thus, the damping capacity and vibration-fracture resistance can be significantly improved.