Electroless nickel plating is an auto-catalytic chemical technique used to deposit a layer of a nickel alloy on a metal surface whose main purpose is to prevent corrosion and wear.
Electroless nickel plating has several advantages versus 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.
Before plating, the metal is cleaned by a series of bases and acids to remove any dirt, soil, or other contaminants to ensure an efficient and uniform plating process. The cleaning processes are intertwined with rinsing processes to prevent any unwanted chemicals from adhering to the surface. De-greasing removes oils from surfaces and acid cleaning removes scaling.
The plating requires an activation, which is usually completed with a weak acid etch or nickel strike. Immediately following the plating process, the metal is finished using an anti-oxidation or anti-tarnish chemical.
There are many advantages to electroless nickel plating, which include:
1. Even coating on complex parts can be readily achieved.
2. Plating volume and thickness can be fully customized to the customer specifications.
3. The process can plate recesses and blind holes with stable thickness.
4. Chemical replenishment can be monitored automatically.
5. Complex filtration methods are not required.
6. Matte, Semi Bright or Bright finishes can be obtained.
Each type of electroless nickel also has particular advantages depending on the application and type of nickel alloy. The three main types vary largely on the amount of phosphorus used in the nickel chemistry.
Low phosphorus electroless nickel
1. Hard deposits
2. Very uniform thickness
3. Excellent corrosion resistance in alkaline environments
Medium phosphorus electroless nickel
1. Very bright and semi-bright options
2. High speed deposit rate
3. Very stable
4. Used for Slurry Disposal Industries
5. The most common type of electroless nickel applied
High phosphorus electroless nickel
1. Superior corrosion protection
2. Excellent acid resistance
3. Lower porosity
4. Non-magnetic, when phosphorus content is greater than 11.2%
5. Less prone to staining
6. Pit-free deposits