Wetting, solder flux chemistry

Flux is sometimes thought of as a catalyst that lowers the surface tension between the molten solder and a metal surface [98]. In reality, the chemistry of flux interactions at oxide surfaces can be very complicated and involve acid-base, oxidation-reduction, and coordination-type and adsorption-type reactions discussed in later sections [102-104]. Spalik prefers to think of most fluxes used for electronic soldering as substances that react as Bronsted-Lowry acids with metallic oxides to form their respective salts and water, and that the salts serve as surfactants that promote solder wetting. 

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