Ultrasonic dissolution of solid Al in liquid Sn during soldering: Modeling and equation, trend prediction, accelerating effect

Abstract

Soldering of ceramics/metals using an inactive commercial solder with the advantage of low cost has wide application prospects. The dissolution behavior of base metal could not be quantified, which has been a basic issue for the joining design. This work investigated the dissolution of the solid Al in liquid Sn with and without the ultrasound. The physical model for the dissolving process was established based on the experiments. The relationship equation of the average concentration of Al ($C_a$) and soldering time was derived by using the Nernst-Brunner principle. The key parameters of limiting solubility ($C_0^L$) and dissolution rate constant ($K$) were obtained through dissolving experiments of liquid Sn to solid Al. The calculation results show that the effect of soldering temperature, and thickness Sn layer on the Al concentration ($C_a$) and dissolution rate ($d{C}_a/dt$) under ultrasound is weaker than that without ultrasound. Compared to the condition without ultrasound, the value $K$, the maximum value of $C_a$ and $d{C}_a/dt$ was increased by 5.8 times, 4.5 times, and 52 times at 250 °C under the ultrasound action, respectively, and the activation energy of dissolution was reduced by 41 %. The mechanism of ultrasonically accelerating dissolution of the solid Al by the liquid Sn has been revealed by using the bubble dynamics principle. It will provide a guideline for the design of soldering ceramics/metals using an inactive commercial solder.