Reduction of metallic surface oxides via an electrochemically-generated redox species

A new method is described for removing oxides from metallic surfaces via electroless reduction by the reducing member of a redox couple that is electrochemically regenerated in a closed loop. On tin-lead coatings, which are widely used to enhance the solderability retention of electronic components and circuit boards, naturally-formed oxides are reduced to the metallic state within 10 s by either vanadous or chromous ions in acidic sulfate solution. Wetting balance data for wire specimens show that this reduction treatment is an effective means of restoring and ensuring solderability.