The adsorption of Ag3Sn nano-particles on Cu-Sn intermetallic compounds of Sn-3Ag-0.5Cu/Cu during soldering

The interfacial reactions between Sn-3Ag-0.5Cu solder and Cu substrate at 250 degrees C and 300 degrees C from 30s up to 1800s were investigated. The average size of the Ag3Sn nano-particles adsorbed on the Cu6Sn5 intermetallic compounds as a function of soldering temperature and time were studied. The results show that the adsorption of Ag3Sn particles occurs during solidification process and the number of Ag3Sn particles increases with the morphology changing of Cu6Sn5 intermetallic compounds. When soldering at a fixed temperature, the average sizes of the Ag3Sn nano-particles are almost the same with the different soldering durations. However, the Ag3Sn nano-particles observed on intermetallic compounds are smaller at 300 degrees C than those at 250 degrees C. The Ag3Sn particles arrange in line in the same plane and the arrangements of Ag3Sn lines order two perpendicular orientations, but there are no relationship with the Cu6Sn5 surface orientations. (C) 2009 Elsevier B.V. All rights reserved.