Gold Plating

Definition - What does Gold Plating mean?

Gold plating is a method of depositing a thin layer of gold onto the surface of another metal, most often copper or silver (to make silver-gilt), by chemical or electrochemical plating.

Gold plating is often used in electronics to provide a corrosion-resistant, electrically conductive layer on copper, typically in electrical connectors and printed circuit boards. Gold plating of silver is used in the manufacture of jewelry.

Corrosionpedia explains Gold Plating

Gold has the highest standard electrode potential among plating materials and is therefore the most noble material used for plating with the highest corrosion resistance. Due to the high cost of material, gold plating is often so thin that the final coating is not free of pores. These pores are the cause of corrosion of electrically conductive surfaces with protective coatings. Therefore, minimization of both the number and the size of pores during gold plating is of prime concern.

There are several types of gold plating used in the electronics industry:

  • Soft, pure gold plating is used in the semiconductor industry. The gold layer is easily soldered and wire bonded.
  • Bright hard gold on contacts, with a purity of 99.7-99.9%. This often contains a small amount of nickel and/or cobalt, therefore the plating baths cannot be used for semiconductors.
  • Bright hard gold on printed circuit board tabs is deposited using a lower concentration of gold in the baths. It usually contains nickel and/or cobalt as well.
  • Soft, pure gold is deposited from special electrolytes. Entire printed circuit boards can be plated. This technology can be used for depositing layers suitable for wire bonding.

Soldering gold-plated equipment can be problematic as gold is soluble in solder. Solder which contains more than 4-5% gold can become brittle.

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