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Electrical Bonding of Connectors

We have various products with electrical bonding requirements. Our choices in connector bodies are nickel plated or cadmium plated MIL-DTL-38999 connectors. Which is the better choice, strictly from the electrical resistance perspective? The contact surface is MIL-C-5541E, class 3. In the past we have had issues in trying to meet the MIL-B-5087 requirement when using cadmium plated connectors, but have had no issues when using passivated stainless steel connectors.

Ann Shackleford
- Cincinnati, Ohio, USA
2005

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Hi Ann. Cadmium is a cumulative environmental toxin that should only be used, if ever, when it's unique combination of properties is required. Those properties include galvanic compatibility with aluminum (the Mil-C-5541 surface you are connecting to), lubricity and good stick-slip properties, freedom from bulky and sticky corrosion products, corrosion resistance, and maybe some resistance to biological growths.

If you have found stainless steel or nickel plated connectors satisfactory, you should not use cadmium plated ones. Best of luck.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
2005