What sort of Nickel coating is used here?

[funding]

Hi all,

I have a Copper part which is Nickel coated from outside. Does anybody has any clue what method of Nickel coating was used here - see attached photos. The layer is very thin, edge lift is not seen even under microscope. Might be few micron or less. Also strangely internal bores are not coated, and it looks like applied with brush but so thin layer rules out brush painting. Also this pushes me to thing that it was not immersed in to any liquid and respectively not wet chemical or galvanic process. Can it be some sort of thermal spray? Or may be vacuum sputter coating like for scanning electron microscopy?

 

[Metaljon]

A part like this would normally apply a nickel coating by a electroless nickel process. Can be quite thin less than 10 microns in thickness.

http://en.wikipedia.org/wiki/Electroless_nickel_plating

http://nz.linkedin.com/pub/jonathan-smith/39/25/589

 

[TVP]

My initial thought is the same as Metaljon: immersion in an electroless nickel bath, with the various internal bores masked or plugged. Definitely not thermal spray.

 

[TomDOT]

Agreed. Most likely electroless nickel plating, with masking and/or plugging. The pattern of the exposed copper on that face is pretty telling - it appears the mask was a bit off-center.