Chemical deposition without external electricity.

Electroless deposition or electroless plating is defined as the autocatalytic process through which metals and metal alloys are deposited onto conductive and nonconductive surfaces.

Electroless nickel immersion gold (ENIG or ENi/IAu), also known as immersion gold (Au), chemical Ni/Au or soft gold, is a metal plating process used in the manufacture of printed circuit boards (PCBs), to avoid oxidation and improve the solderability of copper contacts and plated through-holes.

Electroless nickel-phosphorus plating, also referred to as E-nickel, is a chemical process that deposits an even layer of nickel-phosphorus alloy on the surface of a solid substrate, like metal or plastic.

a chemical process that deposits an even layer of copper on the surface of a solid substrate, like metal or plastic.