Journal of SMT Article
On the Corrosion Mechanisms of Common Printed Circuit Board Surface Finishes in Three Different Sulfur-Rich Environments
Company: Western Digital Technologies, Inc.
Date Published: 3/1/2017 Volume: 30-1
Different surface finishes were found to exhibit different forms of corrosion, which result in fundamentally different corrosion outcomes. Corrosion of ENIG proceeded by stress-corrosion cracking (SCC) of the nickel phosphorous plating, which was followed by pitting/crevice corrosion of the underlying copper pad in the vicinity of compromised NiP regions. ImAg finishes corroded by a combination of crevice and galvanic mechanisms, primarily in solder mask defined (SMD) pad regions and those directly underneath compromised ImAg plating. Corrosion of PCB finished with organic solderability preservative (OSP) proceeded by way of a uniform/pitting corrosion mechanism.
Creep corrosion, printed circuit board, surface finish, copper sulfide
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