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Bright Nickel vs Sulfamate Nickel as an Undercoating

Hi everyone,
I work for a electronics company that makes connectors. Many of these connectors use gold over nickel contacts. The contacts are made from either brass or copper. When we plate these contacts we use nickel as a undercoat (50 to 150 microinches). We are currently using sulfamate nickel as the undercoat, mainly because the gold adheres to it better. Recently I've been asked if I could use a bright nickel as a undercoat, so the contacts look brighter when finished. My question is can I use bright nickel as a undercoating? And if so, will I start having adhesion problems? Which is the best undercoating?

Jerry Hannibal
plating shop employee - Beverly, Massachusetts USA
September 23, 2008

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September 23, 2008

Hi, Jerry. I would not expect an adhesion problem, but bright nickel occludes organics (that's why it's bright) that will cause a problem if the connector gets quite hot. I believe it's considered a poor idea to use bright nickel in electronics applications.

Regards,

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey

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September 24, 2008

Bright nickel often contains organic compounds that can cause adhesion problems when another coating is applied. You can overcome this by using a nickel-cobalt bath, but this gets expensive and needs careful control.

I would suggest you use normal dull nickel with no additives. If the nickel is being overplated, why do you want it bright - is it just to maintain the reflectivity once it is recoated?

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

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First of two simultaneous responses --

From my experience of reel-to-reel plating of electronic connectors....I NEVER used bright nickel ALWAYS sulphamate nickel under gold, tin-lead, etc.I was lead to believe there was conductivity issues/ oxidation layers associated with the organics in bright but I would recommend another contributor to confirm this?

Nigel Gill, BSc MIMF MRSC
- Glasgow, Scotland
September 24, 2008

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Second of two simultaneous responses --

Jerry,
Ted is correct. Bright Ni does not fare well in electronic applications. There are semi - bright Ni sulfamate formulations that may suit you and are fine for what you do. I always believed that jewelry should look bright, connector finishes should be plated to achieve the best electrical properties possible. Bright is not always better. Good Luck!

Mark Baker
Process Engineer - Syracuse, New York
September 24, 2008