Evaluation of solderbility of aluminum using a surface tension method
1990 Volume 40 Issue 3 Pages 182-187
Details
1990 Volume 40 Issue 3 Pages 182-187
Solderbility of aluminum was evaluated mainly by the wetting time obtained from the wetting force-time curves of a surface tension method. Used flux was composed from triethanolamine, ammonium fluoroborate and tin borofluoride. Increase of Sn-Zn solder bath temperature decreased the wetting time, Tw. The shortest Tw was shown in the Sn-20Zn solder in the temperature range of 300-400°C. At about 250°C, Sn-9Zn solder had the best solderbility. Sn-70Zn solder showed longer Tw than that of Sn-(20-40)Zn solders even at high temperatures more than 400°C. The ln (1/Tw) was proportional to the 1/T (T: solder bath temperature). The apparent activation energies were ranging 25.9-84.8kJ/mol. The change of activation energies with solder composition was similar to that of interdiffusion of molten Sn-Zn system. Increase of magnesium content in the base metal drastically decreased the solderbility. Cleaning in the hydrofluoric acid improved solderbility, however, commercial alloys with more than 3.5%Mg scarcely wetted.
