Copper plating: application and processes

Copper plating, an intermediate process for protecting metal surfaces

The copper plating process is essential for protecting iron-based materials, since it represents an intermediate preparatory step in nickel plating and chrome plating.

The protective value of these combinations is very high. Also known as copper electroplating, the process consists in the application of a layer of copper (electrolytically), which takes place in electrolytic baths.

Such baths may be alkaline (the electrolyte is complex cyanide) or acidic (the electrolyte consists of sulfuric acid and copper sulphate). Alkaline baths are the most common when copper plating iron, while acidic baths are used to add a thicker layer of copper after treatment in alkaline baths.

Cyanide baths: the most common processes for copper plating iron

Common cyanide baths contain a low copper content, so they are also known as diluted alkaline cyanide baths. Their wide use is mainly due to their characteristics: high penetration and adhesion of deposits.

Copper plating in cyanide baths can be carried out in two different ways:

1. Cycle with periodic current inversion (15-second deposit, 5-second inversion): greater deposit uniformity (brighter, without pores) due to the absence of roughness, which is in turn due to the action of the anodic current.
2. Cycle with interrupted current (8-second deposit, 2-second interruption): high gloss and use of higher current densities.

Copper plating is applied to aluminium, zinc (and their respective alloys) and stainless steel (the latter especially in the automotive sector).

The Impreglon surface coatings similar to copper plating include Teflon PTFE and Teflon PFA treatments, although the typical copper colour is not applied.