Goudplating

Goudplating, or gold plating, is the deposition of a thin layer of gold onto a metal surface. It is used to improve appearance, corrosion resistance, electrical conductivity, and solderability while using only a small amount of gold. Common substrates include copper, nickel, brass, and steel, often with an underlayer such as nickel or copper to promote adhesion and uniformity.

Gold is applied through several methods. Electroplating uses an electrolyte containing soluble gold salts and an external current to reduce gold onto the substrate; baths may be cyanide-based or non-cyanide, depending on safety and environmental requirements. Immersion plating (chemical displacement) coats the surface by a redox reaction where a more reactive metal dissolves while gold is deposited, producing a very thin layer. Electroless plating deposits gold autocatalytically from a chemical solution without external current. For decorative or high-purity coatings, physical vapor deposition (PVD) or chemical vapor deposition (CVD) can be used to create thicker or more uniform films.

Thickness and quality are important considerations. Gold layers are measured in micrometers or microinches; typical thin gold flash for electronics ranges in the tenths of a micrometer, with thicker coatings used for wear resistance or jewelry.

Applications include electrical connectors, contact surfaces, printed circuit boards, jewelry, and decorative hardware. Advantages include corrosion resistance and reliable solderability; limitations involve cost, wear of thin layers, and environmental and safety concerns related to certain plating baths, leading to regulation and a shift toward non-cyanide alternatives.