What is the Best Lubricant for Extending the Life of Gold Plated Contacts?

[the_emi_guy]

Can anyone recommend a lubricant for extending the life of frequently cycled (once per day) gold plated contacts? It's low voltage (couple volts), but exposed to some moisture so if the plating wears through it corrodes.

 

[CWatters]

Google contact lubricant..

https://www.electrolube.com/pdf/contact-lubricants-brochure-electrolube.pdf

 

[CWatters]

Different grades of switch have different thicknesses of gold plating. Perhaps worth finding better contacts.

 

[Tom.G]

You don't give any details of the actual use, but here is something to keep in mind.

The problem with Gold though is it vaporizes at over a few tens of milliamps of current, especially if there is an arc. Arrgghhh, tradeoffs.

If the atmospheric pollution is just water, the Gold may not be needed if the contacts have good wiping action; as you get with an open-frame relay. Most low cost switches -- especially the miniature ones -- use butt contacts with no wiping action at all.

Decades ago, we used Cramolin brand cleaner/lubricant on gold relay contacts in analog computers. We would always find a few relays that needed treatment at the monthly maintenance cycle. Cramolin no longer exists (I think they were bought out) so the CAIG Laboratories "DeoxIT" (http://www.caig.com) seems the 'go to' source now.

What is the actual use of your switch?

 

[the_emi_guy]

Sorry for leaving this thread hanging...and thanks for the links.

Application is personal, specifically hearing aids related.
Hearing aids must be turned off before stored in their container else they whistle from feedback.
Many hearing aids require the battery door to be popped open to turn them off, so this happens every day.
Popping battery door rubs battery against BeCu contacts, eventually wearing off gold plating.

Gold plating does wonderful job preventing corrosion in mildly harsh environment (sweat, occasional rain drop).
However, once gold plating wears down the contacts corrode quickly (and hearing aids are expensive).

 

[Baluncore]

You might consider a very small amount of Dielectric Grease.

 

[Tom.G]

@Baluncore had a good idea with the Dielectric Grease.
For cleaning already corroded contacts, a Stainless Steel wire brush works well, and a Brass brush is sometimes adequate. Small S.S. brushes are used in electronics assembly and sold as Soldering Aids. One example of such a brush is at http://www.techni-tool.com/182SO061

 

[jim hardy]

Hearing aids must be turned off before stored in their container else they whistle from feedback.
Many hearing aids require the battery door to be popped open to turn them off, so this happens every day.
Popping battery door rubs battery against BeCu contacts, eventually wearing off gold plating.

Gold plating does wonderful job preventing corrosion in mildly harsh environment (sweat, occasional rain drop).
However, once gold plating wears down the contacts corrode quickly (and hearing aids are expensive).

That's the sort of shoddiness that prompts me to ping a manufacturer "from the top".

There's no reason not to have a robust battery connector. Gold plating is available in varying thicknesses , of course it costs a few cents more to get a nice 1 or 2 micron thick plate instead of that el-cheapo 0.03 micron. I specified 50 microinch in my nuke plant electronic controller.

Here's what AMP, the connector people, says about it:
http://www.te.com/documentation/whitepapers/pdf/aurulrep.pdf

And your battery connector IS a high fretting application.

My advice:
1. Download and print applicable pages from that AMP white paper
2 . Go to webpage of whoever made that hearing aid, click "Investor relations"
2A. Click "Management Team"
2B. click CEO , find address of executive offices
2C. find his resume, see where he was educated
2D. find some paper he's authored or better yet a speech he's given someplace
2E.. Find in that paper or speech a reference to quality and 'doing things right'

3. Write a letter to him with words to the effect

" I read your speech of (date) at (place) and want to commend you for your attention to detail and quality.

Accordingly,
You might want to have your engineering folks take a look at this product. It has a small flaw that is giving your company a bad name.
Hearing Aid model _______ needs thicker gold plating on the battery contacts. They fail after just months of normal use. That's causing me a lot of aggravation.
What's your warranty return rate on that product ?.

Enclosed is a brief extract from an industry leader in technology of electrical contacts.
It makes clear why you shouldn't just pick the cheapest gold plate for something that gets cycled frequently.
I hope it helps you further the education of whatever young engineer specified that part.

When he specifes the thicker plating be sure to apprise your marketing folks so they can brag on how it beats the ears off your competition.

I have enclosed my most recently failed hearing aid , as you can see the plating is gone . I would really appreciate an adjustment of some sort on my next one.Your very truly,

etc etc.

attachmnent : (Extract from AMP paper)

I'd say make your letter friendly in tone.

4. Send your most recently failed device along with the letter in a priority envelope addressed to him personally, preferably hand printed address so he knows you put effort into it ..

I wager you'll get a letter and new hearing aid by return mail.

old jim

 

[Tom.G]

@jim hardy has put forth an eminently good suggestion above. The troglodytes that you have to deal with on the phone are often severly constrained by their immediate "superiors" regarding 'appropriate action.' Of course this is not always the case, but when it occurs, a polite and detailed report to "He Who Does Not Have A Superior" can get amazing results.

[Semi-relevant story]
I once was trying to get technical details about a product and somehow ended up talking with the President of the company on the phone. It happened that he had the relevant department head in his office at the time and, without putting me on hold, told the department head to follow up. After two weeks of no response, I called and again got thru to the President, stating I had not received the information. The information arrived in the mail in three days. I would have loved to overhear THAT conversation!
[End story]

 

[anorlunda]

Carbon or silver or gold impregnated grease in some cases give you contacts as good as plating, yet they don't corrode and you can recoat them with grease if needed. They aren't expensive, and you may need only a gram or two.

 

[Tom.G]

Per the suggestion by @anorlunda, Silver paste at least used to be available at larger electrical supply stores (Not electronic supply). It is used when installing large, high-current busbars. Those busbars are bolted together with a good amount of overlap and you precoat the overlapping regions with the Silver paste to ensure good contact and avoid oxidation of the Copper.

 

[Baluncore]

The critical thing with button cells is leakage across the narrow insulation gap. If you pick cells up with moist fingers they will discharge faster due to leakage. It is important that additives in the lubricant do not enhance that leakage. Grease additives may be to some extent abrasive and conductive. I see no benefit in abrasion where thin gold plate is involved. Also keep dust away from dielectric grease to avoid abrasion.

For those reasons I would use a trace of pure dielectric grease on the insulation to prevent condensation when the device changes temperature. I would also use a film of the same dielectric grease on the contacts. That suggests the entire cell should be coated with a very thin grease film, not the contacts.

 

[the_emi_guy]

Thanks everyone.

@jim hardy
Thanks so much for the detailed response. It is crazy that they sell these things for so much $ and skimp on the plating.