Constitutive Properties of Bulk Solder at `Drop-Impact' Strain Rates

Medium strain rate (0.1/s to 300/s) constitutive properties are needed for accurate modeling of drop impact conditions. This study presents an experimental procedure for obtaining the material properties of solder alloys at these medium strain rates. The effect of grain size on the medium strain rate behavior of solder alloys is also studied, using SnPb alloy as an example. Grain size variation is achieved through different aging conditions. For the lower strain rates tested, yield stress generally increases with aging. Interestingly, for the higher strain rates, the yield stress decreases with less severe aging but increases with more severe aging. In addition, aging causes a decrease in the strain rate sensitivity of the solder.