The finishing.com Hotline: Serious Education ... plus the most fun you can have in metal finishing. Ted Mooney, Webmaster
Electrical conduction properties of nickel plating
Q. Is there a difference in electrical conductive properties between bright nickel plating and electroless nickel plating? I have been using electroless nickel plated beryllium copper for an electrical contact and am finding less than optimal conductivity. Is there another type of plating that would provide good corrosion resistance and better conduction?Kjersha Wanlass
- Berkeley, California, USA
A. Dear Mr Wanlass,
There is a difference in electrical conductivity properties. The specific resistance of electroless nickel with 6-7% P is about 50-70 micro-ohm-cm, in general the more phosphorus the more resistance. For example 3% P gives a resistance of about 30 micro-ohm-cm, 8-9% P gives a resistance of about 90-110 micro-ohm-cm. Heat treatment can lower the resistance a lot. Also the amount and kind of additives in the plating bath influences the electrical resistivity.
The specific resistance of bright nickel is about 12-19 micro-ohm-cm, depending of what kind of bath(chloride,sulfate) and what additives are used. Pure nickel, plated out of a bath without any organic additives,has a specific resistance of about 7-8 micro-ohm-cm. Plating silver over nickel or NiP gives excellent electrical properties and provides good corrosion resistance.
- Eindhoven, The Netherlands
December 15, 2012
Q. I have electrical contact between mild steel to mild steel blocks, diameter 300 mm. The current flowing is 600 A TRMS, AC (50 Hz). I need to know what plating is best in this scenario. Also, will plating lower the contact resistance, as plating introduces two more contacts in principle as steel to steel contact becomes steel to nickel to nickel to steel after plating. Please clear these doubts....Sanjay Patel
research student, high temperature sintering applications - Surat, Gujarat, India
A. Hello Sanjay. Two different types of resistances are involved in contact applications: the internal resistance of the metals, and the contact resistance where the two surfaces are touching, which is high because of dirt and oxides on the surfaces, and incomplete contact.
When two steel surfaces contact each other out in the open air, there is high resistance because of the rust, dirt, and rough surfaces which the electricity must traverse. When two nickel plated surfaces contact each other, the resistance is much lower because the nickel surface is smoother and the oxide film is much thinner. When steel is electroplated with nickel, there is true metallurgical joining of the two surfaces, and very low resistance at that joint. So you will find lower resistance and a much more satisfactory contact by nickel plating the steel surfaces.
Ted Mooney, P.E. RET
Pine Beach, New Jersey
June 28, 2013
Please reply to below:
1 can brass and steel be nickel and than silver electroless plated?
2 is this a good electrical contact for 220 volt ac 0.07 amp current flow, for just resistive load?
3 what contact pressure is required for this load?
- Lahore, Pakistan
June 29, 2013
Q. Please reply as:
1 nickel plating and then silver plating by electrolysis
2 what is pressure required for contact for 220 volt 0.70 amp resistive load?
3 is max surface area of contact better than minimum
- Lahore, Punjab, Pakistan