This surface finish is composed of two layers deposited by chemical processes: a layer of nickel, with a thickness of 3-8 µm, and a subsequent layer of pure gold with a thickness whose value can fluctuate between 0.04 and 0.12 µm. The Gold is the real protective finishing while the nickel is used to prevent the migration of copper into Gold.
It is a planar finish, able to withstand multiple soldering cycles. It is easy to solder, even after long periods of storage; the solder joint is formed between tin and nickel.
The ENIG finishing, which is compliant with the RoHS Directive, is particularly suitable for “fine pitch” printed circuit boards and can be also used for contacting areas.