Prediction of IMC formation during interfacial reactions: Application of CALPHAD approach to electronic package

Intermetallic compound (IMC) formed in the interfacial reaction may exert much influence on the reliability of soldering joint. So, effective prediction of IMC formation at soldering joint may do help to optimize the packaging process. Recently, a semi-empirical criterion has been proposed in our group to predict the formation of intermetallic compounds (IMC) at the interface between different pure elements (J. Mater. Res., 2007, pp. 1502). The advantage of this criterion over other models is that it involves both thermodynamic and kinetic factors thus give more reliable prediction. Even so, only thermodynamic calculation, i.e. CALPHAD method, is involved. Applications of the present criterion to the Cu/In, Cu/Sn, Ni/Sn and Co/Sn systems binary couples and Sn-Zn/Ni ternary couple confirm the reasonability of the new model. Application of this model to other ternary systems is in progress.