The gold layer in the ENIG surface finish is there to protect the underlying
nickel from oxidation/passivation until it is assembled or soldered.
During assembly the gold readily disolves into the solder joint, leaving an
active nickel surface to form the tin nickel inetrmetallic that holds the
joint together.
2uins (microinches) or 0.05 microns is all you need to protect the nickel.
At Shipley we recommend that our customers plate 2 - 4 uins to ensure at
least 2uins are plated on all features.
A thicker gold layer adds cost, and increases the risk of Nickel corrosion.
George Milad
Tech Mrkt Mgr
Shipley Ronal Inc
(516)868-8800 ext 269

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