A corrosion couple experiment reproducing the black pad phenomenon found after the electroless nickel immersion gold process

Abstract

The "black pad" phenomenon, which rarely occurs in electrolessly plated nickel phosphorous (Ni-P) films, was reproduced This work reports that nodular variation of the P content induces potential differences large enough to drive galvanic corrosion when the film is exposed to an electrolyte containing gold cyanide. Subsequent corrosion couple experiments using films with different P contents demonstrated that preferential corrosion occurred at the low P side, and the propensity of forming black pad increased with the difference in P content (Delta P) (C) 2010 Acta Materialia Inc Published by Elsevier Ltd All rights reserved