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Needed: Nickel corrosion performance with Tin ductility

I am searching for a plating solution with the corrosion resistance performance of Nickel plate (salt-fog test) in a more ductile finish. The reason this ductility is necessary is that some of the parts plated features are bent after processing. Nickel plating does not hold up to this stress, where Bright Acid Tin plating does... Bright Acid Tin plating would be the solution if it stood up to salt-fog testing a little better. Possibilities for improvement may be COPPER/TIN/ZINC or TIN/ZINC but I don't know how the appearance of those would hold up to salt-fog tests (because of the zinc)... The material to be plated (barrel) is C360 brass. Any ideas or information are welcome and appreciated.

Randy Blunt
- Gilbert , Arizona, USA
2003

Hi Randy,

I suggest you use Sn-Ni plating on your brass. Without knowing exactly your problem except you want ductile and corrosion resistant plating.

Best Regards,

Bo Kønig
- Odense, Denmark
2003

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First of two simultaneous responses -- 2003

Randy,

There is a finish, discussed a couple of years ago on this forum, called by a number of names: Albaloy, Optalloy, Miralloy, Techni-White. It is a copper-tin-zinc alloy with good corrosion resistance, great solderability, and a whitish color. It takes the finish of the substrate, that is, it doesn't overcome cosmetic defects very well. The bath has incredibly good throwing power. The main reason it is not more commonly used is that it is a cyanide bath, has low efficiency, runs at 150 F, and tends to self-destruct after two or three months (cyanide hydrolysis?). I have run the bath and it is still in use locally (Arizona) in at least two shops.

Bill Vins
microwave & cable assemblies - Mesa (what a place-a), Arizona

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Second of two simultaneous responses --

I thought Sn-Ni alloys were quite brittle, or at least those put down from the formulations developed by the International Tin research Institute (ITRI) were. If you have some other formulations, can you please share them with us. I think there are baths based in copper-tin and perhaps copper-tin-zinc that may meet your needs, but I have never used them.

Trevor Crichton
R&D practical scientist
Chesham, Bucks, UK
2003

Sn-Ni plating is so far I know in use some where in States and less than 10 places in Denmark. I don't know about results from ITRI, and their formulas sorry. What I know is that Sn-Ni plating have throwing power like acid copper, that Sn-Ni plating on brass will follow nearly any deformation you can make to the item. The surface will not break. We have used this plating for 10 years, and I have newer heard about corrosion problems, our products is in daily contact with water. Your chemical supplier can help you more with details about setting up bath.

Hope to have helped you.

Sincerely,

Bo Kønig
- Odense, Denmark
2003