The diffusion of Cu through the grain boundaries of 500nm-thick ion-plated Ag-12at%Sn films was studied at 100 to 250C. The method was based upon the determination of the moment at which Cu first appeared on the Ag-Sn surface. This was done by using Auger electron spectroscopy to determine trace amounts of Cu. It was found that the results could be described by:

D (cm2/s) = 1.3 x 10-7 exp[-0.53(eV)/kT]

Studies of Cu diffusion through ion-plated pure Ag layers were also carried out. In this case, the results were described by:

D (cm2/s) = 2.3 x 10-5 exp[-0.68(eV)/kT]

A.Bukaluk, M.Rozwadowski, R.Siuda: Surface Science, 1988, 200, 381-5