Gold plating-Gold plating types-Custom
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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. This article covers plating methods used in the modern electronics industry; for more traditional methods, often used for much larger objects, see gilding.
Gold plating types
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. Its Knoop hardness ranges between 60-85. The plating baths have to be kept free of contamination.
Bright hard gold on contacts, with Knoop hardness between 120-300 and purity of 99.7-99.9% gold. Often contains a small amount of nickel and/or cobalt; these elements interfere with die bonding, therefore the plating baths cannot be used for semiconductors.
Bright hard gold on printed circuit board tabs is deposited using lower concentration of gold in the baths. Usually contains nickel and/or cobalt as well. Edge connectors are often made by controlled-depth immersion of only the edge of the boards.
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.