Immersion Gold Plating
Immersion Gold Plating is a process that applies a very thin layer of gold by displacement of the surface atoms. This means the coating is not very thick, typically between 3 and 8 micro inches. It offers some corrosion resistance and is used to extend the shelf life of parts waiting for soldering operations.
Immersion gold has been used in aluminum and gold wire bonding and the manufacture of printed circuit boards. It should not be used to replace electrolytic gold plating, since its adhesion and thickness is limited compared to a standard electroplated gold.