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The purpose of this paper is to investigate the effects of electric current stressing on damping properties of Sn5Sb solder.

Uniformly shaped Sn5Sb solders were prepared as samples. The length, width and thickness of the samples were 60.0, 5.0 and 0.5 mm, respectively. The damping properties of the samples were tested by dynamic mechanical analyzer with a cooling system to control the test temperature in the range of −100 to 100°C. Simultaneously, electric current was imposed to the tested samples using a direct current supply. After tests, the samples were characterized using scanning electron microscope, electron backscatter diffraction and transmission electron microscope, which was aimed to figure out the damping mechanism in terms of electric current stressing induced microstructure evolution.

It is confirmed experimentally that the increase in damping properties is due to Joule heating and athermal effects of current stressing, in which Joule heating should make a higher contribution. G–L theory can be used to explain the damping properties of strain amplitude under current stressing by quantitative description of geometrically necessary dislocation density. While the critical strain amplitude and high temperature activation energy decrease with increasing electric current.

These results provide a new method for vibration reliability evaluation of high-temperature lead-free solders in serving electronics. Notably, this method should be also inspiring for the mechanical performance evaluation and reliability assessment of conductive materials and structures serving under electric current stressing.

This study aims to experimentally assess the effect of thickness and preparation direction on the damping properties of Sn58Bi and Sn3.0Ag0.5Cu solders.

Sn58Bi and Sn3.0Ag0.5Cu solder strips with different thicknesses were prepared from the bulk in longitudinal and horizontal directions, and the ratio of loss modulus and storage modulus of the samples was measured by the dynamic mechanical analysis method as the index of damping properties.

Sn58Bi and Sn3.0Ag0.5Cu solders exhibited viscoelastic relaxation, and their damping properties decreased with decreasing thickness. The damping properties of both solders had no obvious difference in longitudinal and horizontal directions. Sn58Bi has a more obvious high-temperature damping background than Sn3.0Ag0.5Cu solder. In addition, compared with Sn58Bi solder, Sn3.0Ag0.5Cu solder had an obvious internal friction peak, which moved toward high temperature with increasing frequency. The activation energies of Sn58Bi solder with a thickness of 0.5 mm at the longitudinal and horizontal directions were 0.84 and 0.67 eV, respectively, which were 0.39 and 0.53 eV, respectively, for the Sn3.0Ag0.5Cu solder.

The damping properties of Sn58Bi and Sn3.0Ag0.5Cu solder decreased with decreasing thickness, while their damping properties changed insignificantly when they were prepared from different directions. The internal friction peak of Sn3.0Ag0.5Cu solder moved to higher temperatures with increasing frequency.