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 ten seconds by either vanadous or chromous ions in acidic sulfate solution. Wetting balance data for wire specimens show thet this reduction treatment is an effective means of restoring and ensuring solderability.