Francais | English | Espanõl

From Wikipedia, the free encyclopedia

Electroless nickel plating is achieved by forming a thin layer of nickel phosphate on a solid workpiece such as metals and plastics. The thickness of the plating film is usually measured in micrometers. It is used in aviation, automotive, electronic fabrication (HDD), and printing press manufacturing among others. This plating technique is to prevent the occurrence of oxidation (rust), to make or restore fine dimension and to improve the surface finish of a particular component.

Electroless nickel plating has several advantages versus nickel sulfamate (electrolytic) plating. Free from flux-density issues, it provides an even deposit regardless of workpiece geometry, and with the proper pre-plate catalyst, can deposit on non-conductive surfaces

Before performing electroless nickel plating, material to be plated must be cleaned by a series of cleaning chemical such as bases and acids, this process is called the pre-treatment process. Failure to remove unwanted "soils" from the part's surface would result in poor plating. Each pre-treatment chemical must be followed by water rinsing (normally two to three times) to remove the chemical that adheres to the surface. Degreasing removes oils from surface; acid cleaning removes scaling. Activation is done with a weak acid etch, or nickel strike, or in the case of non-metallic a proprietary solution. After the plating process, plated materials must be finished with an anti-oxidation or anti-tarnish chemical (trisodium phosphate, chromate etc) and pure water rinsing to prevent unwanted stains. The rinsing materials must then be completely dried off or sometimes baked off to obtain the full hardness of the plating film.

Since electroless nickel plating is a non-toxic plating, this method is commonly used in medical devices. In our day to day life, we may encounter an item that was electroless nickel plated such as door knobs, kitchen utensils, bathroom fixtures, electrical/mechanical tools and office equipment.

Basic control points in electroless nickel plating

1. Chemical concentration
2. pH of the solution
3. Contaminants in the solution
4. Temperature
5. Surface area of the substrate or item to be plated.

Advantages

1. Does not use electrical power.
2. Even coating on parts surface can be achieved.
3. No sophisticated jigs or rack is required.
4. There is flexibility in plating volume and thickness.
5. The process can avoid plate recesses and blind holes with stable thickness.
6. Chemical replenishment can be monitored automatically.
7. Complex filtration method is not required.

Disadvantages

1. Lifespan of chemicals is limited.
2. Waste treatment cost is high due to the speedy chemical renewal.