Low Contact Resistance Plating. Alternatives to gold plating?

A. IC's with tin or solder plated leads (I don't know how much lead they use) are commonly used both in zero-insertion-force sockets and conventional spring sockets, even for low-voltage DC circuits. On the other hand I've seen circuit boards with tin or solder plated fingers used in control systems in bad environments, and the experience was miserable. I can't count how many times I pulled boards out and reinserted them so that the scraping action would present a clean contact surface so they would work again.

I suspect that if the contacts are sealed, and the application is not very low voltage, that it probably would work for 20 years. But this is based on the anecdotal evidence of my very limited observations, and I hope that somebody who really knows what they're talking about pipes in.

Electroless nickel is very widely used, but perhaps for somewhat higher voltages (the battery charging contacts on almost everything these days use nickel plated or electroless nickel contacts).

As for palladium, that should be a satisfactory substitute for gold. It's somewhat lighter and somewhat cheaper per pound, roughly halving the cost. AT&T Nassau Metals division used to market a plating process, but with the constant changes in corporate structures these days, I wouldn't know offhand how to locate a supplier of proven palladium plating processes.

A. Palladium is widely used as a substitute for gold on electrical contacts, Arthur. Talk to your supplier about installing such a bath. Recognize that all non-precious metals tarnish, so at very low signal levels they won't work. But you'll often see electroless nickel plating on the power circuits and earphone adapters of a device like a cell phone while gold plating is used on the digital circuits of the same device.

Regards,

A. Precious metals don't tarnish or oxidize. I believe that when contact resistance is critical, precious metal plating is the only alternative. An under layer of nickel is a very good idea, if not a requirement, to prevent diffusion of copper into the gold. There may be slightly less expensive alternatives to gold though, like palladium, and you might look into that. Good luck.

A. Hi Iftikhar. We appended your inquiry to a thread which discusses your issues. Nickel plating or electroless nickel plating are widely used for low contact resistance ... but not super low. Precious metals are the only non-tarnishing conductive materials. Good luck.

Regards,

 Sorry cousin, but no. Extensive elaboration about generalities is a subject for books, not a public forum.

But if you elaborate your own exact situation -- what these pins are, what voltage & amperage they are expected to carry, whether they are for one-time soldering or wire wrapping vs. millions of insertion cycles, anticipated lifecycle, environmental exposure situation, etc., additional help may certainly be possible.

Meanwhile, a great way to learn is to try to help others with their problems (and it's your turn). You very quickly find out what you know, don't know, and thought you knew but actually didn't :-)

Thanks, and regards,

A. Cobalt can also be used as substitute as it's more conductive than nickel.