Solid state interaction between a Sn-Ag-Cu-In solder alloy and Cu substrate

The solid-state reactions between the Sn-3.0Ag-0.4Cu-7.0In (wt%) solder and Cu substrate, at temperatures 100, 125,150 and 180 degrees C and for aging times up to 1506 h, are studied. The interfacial layers formed between solder and substrates are characterized using optical and scanning electron microscopy and electron microprobe analysis. Two ternary intermetallic layers Cu-6(Sn,In)(5) (eta-phase) and Cu-3(Sn,In) (epsilon-phase) are formed at the interface between the solder and Cu substrate. Kirkendall voids were observed at Cu/epsilon interface as well as inside the epsilon layer. The growth kinetics of eta and epsilon phases and the activation energies for their growth are calculated and results are compared with growth kinetics of these phases in the case of Sn-Ag-Cu solders/Cu systems. (C) 2013 Elsevier Ltd. All rights reserved.