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Corrosion resistant plating for flashlight springs and contacts

 

We have designed a berylium copper spiral spring and a flat metal phosphor bronze spring contact both for use in a flashlight type of electrical circuit. We find that oxidation of the electrical contact surfaces of these two parts reduces electrical flow. Please recommend a plating material that will inhibit corrosion having high electrical conductivity.

Alex Wojciechowicz
- Farmingdale, New Jersey

Gold - that's about as good as it gets for combination conductivity and corrosion resistance.

Dan Brewer
chemical process supplier - Gurnee, Illinois

Electroless nickel would be the cheapest way to go. Gold over nickel would offer the most reliable contact; there's no such thing as "gold rust". Gold objects buried in the ground for thousands of years are as shiny and beautiful as they were upon creation.

Michael Brewington
- Salisbury, Maryland, USA

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Your question has a very practical ring to it. My first inclination would be to use the noble metals such as gold or silver. However, due to cost constraints, these may not be practical for your application. One finish that may be worth looking into might be tin/zinc alloy plating. The tin (75%); Zinc (25%) is very corrosion resistant, and yet gives decent conductivity, and the cost to plate will not create anxiety in the accounting department.

These deposits usually can be plated from a proprietary Neutral pH solution. They are NOT pretty to look at, but are strictly functional. If the parts are brass, a barrier coat can be laid down to prevent any migration.

Ed Budman [dec]
- Pennsylvania
With deep sadness we advise that our good friend Ed passed away Nov. 24, 2018