Properties of Electroless Nickel (EN) Plating
The properties of electroless nickel are responsible for the rapid growth of its use as a functional metallic coating in recent years. This is no other coating that has the combination of properties offered by electroless nickel.
•Corrosion resistance: One of the most common reasons for using electroless nickel coatings in functional applications is its excellent corrosion resistance.
•Heat Conductivity: The heat conductivity of an electroless nickel coating containing 8 to 9 percent phosphorus is 0.0105 to 0.0135 cal-cm/sec/degree C.
•Melting Temperature: The melting temperature of electoless nickel coatings vary widely, depending upon the amount of phosphorus in the deposit. A generally accepted melting point is approximately 1616F for coatings with approximately 7 to 9 percent phosphorus.
•Magnetism: Electroless nickel coatings containing greater than 8 percent phosphorus are considered to be essentially nonmagnetic as plated. Coating thickness measurements with devices which rely on the nonmagnetic characteristic of the coating may become inaccurate and require special calibration in the phosphorus content of the coating is below 8 percent. Heat treatment of electroless nickel plated parts will increase the magnetism of the plated part.
•Solderability/Weldability: Electroless nickel coatings are easily soldered with a highly active acid flux. Soldering without a flux or with a mildly active flux can be difficult especially if the plated part is exposed to the atmosphere for an extended period.
•Adhesion: Excellent adhesion can be achieved on a wide range of substrates, including steel, aluminum, copper and copper alloys. Heat treatment is commonly used to enhance the adhesion of electroless nickel coatings over all substrates.
•Thickness: One of the key properties of electroless nickel plating is the ability to deposit the coating to produce a wide range of coating thickness, with uniformity and minimum variation from point to point. This uniformity can be maintained while plating both large and small parts. It is a great coating for parts with complex geometries that include recessed areas.
•Brightness: The brightness and reflectivity of electroless nickel vary significantly. The reflectivity is also affected by the surface finish of the substrate. Basically the finish of an electroless nickel plated part will mirror the surface of the part plated. Thus a bright electroless nickel deposit with appear dull if the surface of the part being plated is rough.