Studies of Cu-Sn interdiffusion coefficients in Cu3Sn and Cu6Sn5 based on the growth kinetics

Abstract

In this work, we set up a kinetic model of Cu3Sn (ε) and Cu6Sn5 (η) growth based on the reaction/diffusion theory. The kinetic equations of the ε and η layers growth were established according to the principle that the growth was controlled by the interdiffusion of Cu and Sn atoms. We derived the kinetic equations with and without consideration of the volume change caused by phase transitions, where the Cu-Sn interdiffusion coefficients ((D˜ε, D˜η) were all included as dominant factors. On this basis, the interdiffusion coefficients at 130 °C ~ 200 °C were determined under the two conditions, and results showed that the volume change affected the accuracy of the calculation of D˜ε and D˜η to some extent.