Differential scanning calorimetry was used to characterize the interdiffusion of solder/metal couples. The heat of formation of Cu3Sn from Cu6Sn5 and Cu thin films was found to be equal to -4.3kJ/mol; a result which was similar to that found for bulk samples. The nucleation of Cu3Sn began at temperatures near to 360K, but the nucleation and initial growth of Cu3Sn was not a well-defined Arrhenius process in these couples. Later parts of the differential scanning calorimetry scans were identified with the diffusion-limited growth of Cu3Sn. From these results, the interdiffusivity was deduced to be described by:

D (cm2/s) = 0.032 exp[-0.87(eV)/kT]

K.F.Dreyer, W.K.Neils, R.R.Chromik, D.Grosman, E.J.Cotts: Applied Physics Letters, 1995, 67[19], 2795-7