Effects of Organic Acids on Wettability of Sn-0.3Ag0.7Cu Lead-Free Solder

In the assembly of electronic products, developing good organic acid fluxes plays an important role in improving the solderability of lead-free solders. In this paper, a variety of fluxes containing 5% (mass fraction) organic acid activators were prepared. Effects of different activators on the spreading rates of Sn-0.3Ag0.7Cu solder were studied. The results show that: activity of monobasic acids are weak except for benzoic acid; dibasic acids and polybasic acids have relatively strong activity but serious corrosion and slightly less activity persistence. Compounding palmitic acid and adipic acid in the mass ratio of 1:2 as the activator, the average spreading rate of Sn-0.3Ag0.7Cu solder is 71.11% in maximum. Compounding succinic acid and adipic acid in the mass ratio of 3:7 as the activator, the average spreading rate is up to 72.49% in maximum. And solder spots are in-erratic, bright and plump, meeting the quality requirements of electronic micro-connection.