Scanning Micro Reference Electrode Testing of Localized Corrosion at Cu/Solderingtin Interface in Early Stage

The localized corrosion in the early stage of Cu/solderingtin interface was observed by scanning micro reference electrode (SMRE) technique. SMRE results showed that the corrosion of Cu/soldering tin didn′t occur immediately after immersed in 0.5 mol/L NaCl solution. The localized corrosion took place after immersed for about half an hour. With the immersion time extended to four hours, the localized corrosion occured in the interface of Cu and soldering tin, and the degree of corrosion reached the maximum. When immersion time was between five and six hours, the corrosion of the interface and soldering tin became worse gradually. After seven hours, galvanic corrosion was even more remarkable. The soldering tin as an anode was corroded gradually and the copper as a cathode was protected.