Copper plating

1. Characteristics and properties

Copper is a ductile, soft metal with a reddish colour that is easy to machine and work with. It is an excellent conductor of electrical current and heat and is classified as a semi-precious metal. In dry air, at moderate temperatures, it does not react with oxygen, but in humid air, under the influence of the atmosphere, it gradually forms a green layer, the patina, which is occasionally desired for decorative purposes. In non-oxidizing acids, copper is insoluble without the action of oxidizing agents. It is also resistant to bases with the exception of ammoniacal solutions. In alkali cyanides, copper dissolves and complexes.

2. Benefits and areas of application

Galvanically deposited copper coatings are used as intermediate coatings before nickel plating and chromium plating of steels. Copper coatings are most widely used as intermediate layers in the electrical and automotive industries, on steels and in electroplating. In addition, copper layers are used as an outer coating for decorative surfaces with or without subsequent colouring and protective organic coatings.

3. Basic material

The basic materials for galvanic copper plating can be steel, pre-treated stainless steel, zinc die-cast, aluminium and all non-ferrous metals. In contrast to highly stressed workpieces made of steel or zinc die-cast, which receive copper layers of up to 25µm, in the Cu/Ni/Cr or Cu/Ni/Sn or Cu/Sn layer system, for example, only layer thicknesses of 2-5µm are required, which serve as diffusion barriers and to improve the adhesive strength of the layers or to improve corrosion protection.

4. Required delivery condition

The goods provided must be largely metallically bright. Residual oils or residual impurities must be removable with conventional aqueous alkaline degreasers. Oils containing silicone, alkali/alkaline earth and high-pressure additives must be avoided at all costs.