Quasi in situ study about growth kinetics of Ag<inf>3</inf>Sn at the interface of eutectic SnPb/electroplated Ag soder joint in the long-term satellite

Abstract

The interfacial reaction and the growth kinetics of intermetallic compounds between 63Sn37Pb (wt.%) solder and the electroplated silver layer during the solid-state aging were studied in this paper. To measure the growth kinetics of Ag 3 Sn, the product of the interfacial reaction, more accurately, we used the quasi in situ method. And three same joints between solar cells and solder were annealed at 100°C, 120°C and 150°C for various aging durations. The results showed that the electroplated Ag layer gradually transformed into scalloped Ag 3 Sn, and the growth kinetics of Ag 3 Sn was a diffusion-controlled process during isothermal aging. Through measuring the thickness of Ag 3 Sn during the isothermal storage, the activation energy for IMC at eutectic SnPb solder/electroplated Ag layer interface was calculated and the result was 106 kJ/mole. On the basis of the growth kinetics, a correspondence between long-term thermal recycle and isothermal aging was presented. And the relation could be used to replace the long-term thermal recycle with accelerated annealing experiment, which would have a significant meaning for testing the reliability of low earth orbit satellites' solar cells.