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How to check that coating is Electroless Nickel, not electroplating

Is there an easy way identify electroless nickel plating from electroplated nickel if misprocessing happened during the plating?

Math Muhin
Employee - USA
May 12, 2011

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Hi Math,

I would check the uniformity of the layer thickness. Electroless Nickel has the property that plating thickness is very uniform, regardless of the shape of the part, while electroplating will have higher build-up on areas with higher current densities, unless near perfect conforming and auxiliary anodes were used, but still. When the shape is quite complex, it should be easy to detect using a simple layer thickness determining device. What kind of part are we talking about about (shape/size)?

Hope it helps.

Best regards,
Jeroen

Jeroen Visser
- Geldrop, Netherlands
May 17, 2011

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First suggestion is pretty good - electroplated nickel will "dogbone" or buildup non-uniformly whereas EN will be uniform particularly in deep recesses and through holes. Perhaps as easy is to check the coating for the presence of phosphorus - any XRF thickness tester should be able to do this. EN requires phosphorus (or boron) in order for the reaction to be indeed electroless or in another word, autocatalytic.

Milt Stevenson, Jr.
Syracuse, New York
May 19, 2011

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Hardness is another easy way to find out. Most as-plated EN coatings will be in the range of 48-52 Rc (and up to 66-68 when heat treated) whereas electro-nickel will be 35 Rc at the most. For precise readings microhardness testers are required (such as Vickers or Knoop) preferably on cross sections to avoid any influence of substrate hardness. Alternatively, a scratch test made over the plated surface with a sharp hard object such as a pocket knife or file will give you a good clue.
G. Marrufo-Mexico

Guillermo Marrufo
Monterrey, NL, Mexico
May 22, 2011