Localised aqueous corrosion of electroless nickel immersion gold-coated copper

M. Mousavi*, A. Kosari, J. M.C. Mol, Y. Gonzalez-Garcia

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

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Electroless nickel (Ni) immersion gold (Au), commonly referred to by the acronym ENIG, is the most common protective coating applied on the exposed copper (Cu) traces of printed circuit boards (PCBs). In this work, we elucidate the local corrosion mechanism of the ENIG-Cu system by applying microscopic, surface analysis and electrochemical techniques with high spatial resolution to provide a comprehensive understanding of the complex local corrosion mechanism of the ENIG-Cu system. The corrosion initiation is highly localised and associated with pores or micro-defects in the Au layer. The corrosion initiates by the dissolution of the underlying Ni layer, being less noble than Au. The dissolution propagates in lateral and perpendicular directions relative to the surface in an elliptical fashion. With time, the direction of corrosion propagation changes to a predominantly lateral attack of the Ni layer. The corrosion process is governed by the cathode/anode ratio of the Au/Ni galvanic couple.

Original languageEnglish
Pages (from-to)520-530
JournalCorrosion Engineering Science and Technology
Issue number6
Publication statusPublished - 2022


  • corrosion mechanism
  • cross-sectional FIB analysis
  • Electroless nickel immersion gold
  • PCB
  • SECM


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