Electroless Nickel Plating (EN Plating)

Definition - What does Electroless Nickel Plating (EN Plating) mean?

Electroless nickel (EN) plating is an auto-catalytic reaction used to deposit a coating of nickel on a substrate such as metal or plastic. It provides wear resistance, hardness and corrosion protection of the substrate. It is also commonly used as a coating in electronics printed circuit board manufacturing, typically with an overlay of gold to prevent corrosion.

EN techniques can also be used to manufacture composite coatings by suspending powder in the bath.

Corrosionpedia explains Electroless Nickel Plating (EN Plating)

Electroless nickel plating is a chemical reduction method which depends upon the catalytic reduction technique of nickel ions in an aqueous solution and the subsequent deposition of nickel metal on the substrate without the use of electrical energy.

This electroless process greatly improves the object's resistance to galling and leaves a predictable, uniform nickel coating for high-precision parts, which can be applied to both ferrous and non-ferrous surfaces of any geometry. Electroless nickel coating is often less porous than electroplated nickel and hard chrome, providing barrier corrosion protection to steel, and can also be applied with little or no compressive stress, making it gentle in application.

This process provides a large flexibility of thickness and volume of the plating on metal surfaces, and can easily fill recesses or pits in the metal surface, resulting in a uniform surface finish. This also allows for a wider variety of industrial parts to be plated such as:

  • Oil field valves
  • Pumps
  • Drive shafts
  • Electrical/mechanical tools
  • Engineering equipment

The most common variants of electroless nickel plating are:

  • Composite electroless nickel, in which silicon carbide (SiC) particles are co-deposited with the nickel to enhance its strength and wear resistance
  • Duplex electroless nickel, where an undercoat containing 14% phosphorus is used with a top coat of 5% phosphorus

Electroless nickel plating has several advantages over electroplating. Free from flux-density and power supply issues, it provides an even deposit regardless of workpiece geometry, and with the proper pre-plate catalyst, can deposit on non-conductive surfaces.

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