Splashing of Sn-Bi-Ag solder droplets

In this paper, we study the behavior and spreading dynamics of molten metallic alloy droplets. Five solders, including three rare earth elements and a commercial alloy, were used to assess their splashing behavior in terms of the material and impact conditions. The metallic solders were melted down in a heated chamber (oven) and then dripped onto a smooth copper flat substrate as spherical droplets. The impact of each alloy droplet was recorded and analyzed by high-speed imaging and image analysis to obtain the impact speed, the droplet size, and the dynamic contact angle. Our results show that the impact behavior is well parameterized by the splashing ratio, a dimensionless number encompassing the impact and liquid properties, and the maximum dynamic spreading contact angle. Our results are useful to the industry as they provide a criterion to select the maximum soldering injection speed or the droplet size to avoid splashing during soldering or the jetting of molten metals.

Automated summary

In this study, the behavior and spreading dynamics of molten metallic alloy droplets were investigated. The impact behavior of five different solders was analyzed in terms of material and impact conditions. The results showed that the impact behavior could be well described by the splashing ratio and the maximum dynamic spreading contact angle. This study provides useful criteria for selecting the soldering injection speed and droplet size in industrial applications to prevent splashing during soldering or molten metal jetting.