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
December 20, 2012
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.
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
Hi cousin Waseem. The answer to question 1 from June 28th is yes; I can't answer the others from that date.
Regarding your posting from June 29th, I don't understand question 1, and can't answer question 2.
Question number 3 is probably not really answerable because on a microscopic scale, the smaller contact may actually have more area in contact: knife edge contacts are often used for better contact, and 'wiping' contacts are often employed where flat contacts are used. The area of brass or steel carrying the current may be much more important than how much of the plated contact touches the other plated contact.
As you see, no truly knowledgable reader has responded despite this page being viewed thousands of times. It usually will work better if you can engage a reader in a conversation before presenting a whole list of questions. Nobody enjoys 'flash card quizzes', and nobody enjoys putting "I don't know" on public record ... but even readers who know 5 of your answers would be put into that position :-)
Ted Mooney, P.E.
Pine Beach, New Jersey
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