Contact cleaner for metrology grade connections

[Conrad Hoffman]

We know oxidized copper has a high thermal emf and you need clean connections. Just curious if anybody has any comments on the ability of DeoxIt or similar things to keep said copper contacts oxide free. No idea what is or isn't in DeoxIt, but contact cleaners containing oleic acid have been recommended by some and there's speculation that's one of the components. Oleic fatty acid isn't much of an acid and is the main component of olive oil. I have a bottle of commercial grade oleic and can't say I've been able to detect any real oxide-busting action. Maybe it needs something else to activate it? Can anybody comment on whether it's any better than simple Vaseline as a protectant, or does anybody have other recipes to try? Sure would like to know what was in the old milk-like QT (Quietrol) cleaner of old.

[CalMachine]

I've used DeOxit D5 with decent success.  Using that with some micrubrushes, I was to get into the small female holes of the 34420A/2182 Nanovoltmeter LEMO connectors.  Pulled nothing but green stuff out...  Reminded me of the color of the Statue of Liberty, (wonder why

Also took this to RS925D/720A switch decks contacts with great success.

[MisterDiodes]

I can also vouch for DeOxit products, everything we've used it on is fine and probably had the best success over other stuff.  Wipe off the excess if possible.  Works -very- well on switch contacts at least on everything we've used it on.

We don't normally use an exposed contact grease lube coating in the clean rooms but if you do use one I would suggest a plastic-safe variety.  I know some of the older plastic knobs and insulators can get brittle in the presence of some petroleum distillates so you might want to test on a non-critical area first.  For instance a thin coating of dielectric silicone-based grease might work quite well on the post contacts.

If you're in a clean room or next to a microscope DuPont (and others) make various very inert greases that do not outgass and creep everywhere and on to everything.  If not in a clean room I'm sure something like a thin coat a Vaseline or similar would be fine if it doesn't react to the insulator.  Wherever you are just a -very- thin layer is all it takes - less is more, but it really does help.

[helius]

Careful with that lipid chemistry... oils such as olive oil are predominantly triglycerides, which are fatty acid triesters of glycerol, a sugar alcohol. Olive oil contains triglycerides with oleic, palmitic, stearic, and linoleic acid moieties, in typical positions, as well as various aromatics.
Bare fatty acids taste more soapy than oily and are not appetizing at all.

I don't have specific experience with metrology grade instruments, but one contact protectant that has served me well is polyphenyl ether, see discussion here.

Henkel also makes specialty lubricants (non-migrating, etc) under their Krytox brand.

[Conrad Hoffman]

Don't worry, I'm not using olive oil but commercial grade oleic acid. There's a lot of myth and legend in those links, just like the audio sites I frequent. Here are a couple useful links. Ignore the text on the Santolube site, as they seem to have copied their pump fluid text by mistake. The technical data sheets are correct.
http://www.santolubes.com/products/accl/
https://www.nyelubricants.com/connectors
http://antiqueradios.com/forums/viewtopic.php?t=82058&start=40

FWIW, I've never gotten rotary switches that didn't have some factory applied lube. AFAIK, most pots also have a track lube applied. What I'm really interested in here is if these potions can reduce thermocouple effects and maintain low and consistent resistances.

[texaspyro]

I just finished restoring an EDC MV-100 programmable voltage standard.   The rotary switches were gross.  I used Deoxit 5 on them (recommend by EDC) and then some GC contact cleaner with polyphenol ether lube.  EDC says you must re-lube the switches after cleaning or they will only last a couple of months of use.  They recommended Caig Protectit, now sold as Deoxit Shield (or something like that)

Also look at a product called Stabilant 22 contact enhancer.  Their claims sound like audiophoolery hocus-pocus, but the damn stuff works.  I know of a custom test / burn-in house that uses chip sockets that cost thousands of dollars each.  They were getting less than 100 uses out of them.  With Stabilant that went to at least 1000.  Some of their tests involved measuring nanovolt level signals.

Stabilant is rather pricy stuff.  Oddly, you can get it fairly reasonably at VW auto dealerships.  I think their part number is ZVW186001  Costs around $40 for a small bottle.   A little goes a long way.  My bottle is over 10 years old and half full.

[Moon Winx]

We've always used 200 proof ethyl alcohol to clean connectors with. I couldn't tell you why it works, and maybe there is something better, but we use it on everything that comes into the lab for calibration.  I've tried a couple of flavors of DeoxIt but it would sometimes leave a gummy residue.

[texaspyro]

I keep a bottle of Everclear in the lab (190 proof grain alcohol).  Cleans stuff.  Mix with orange juice and it makes a great screwdriver.  Add some milk of magnesia for a phillps screwdriver.   

[Rsr1985]

I use Lectricare music electronics for cleaning, lubricating and protecting contacts, potentiometers, tube sockets, switches, metal chassis of circuit boards and more. Works great and lasts along time.

[Andreas]

found somewhere in a old HP-Manual:

so I have bought me a complete Kit:
https://www.amazon.de/CAIG-Laboratories-SK-AV35-Audio-Survival/dp/B00C0NTMPE

with best regards

Andreas

[doktor pyta]

@Moon Winx

I've tried a couple of flavors of DeoxIt but it would sometimes leave a gummy residue.

That's interesting. Could You please tell us more details, observations?

[Krytron]

I learned about DeOxit in the Air Force.  I'll look around as I have its chemical name somewhere.  I learned a little will go a long way - a lot of people will spray until its dripping out and thats too much.

Jim WIlliams from Linear Technology also recommended DeOxit for connections and he was talking about their HP3458A and their KVDs.

Freon was a great cleaner - but its basically been outlawed unless you have a system that recycles it.

And I use Everclear also, when I can clean with alcohol.  But you should sample it first to make sure its not gone bad......

[branadic]

I currently have some gear on my desk with pretty rusty copper binding post. Even Deoxit isn't strong enough to remove the oxide. So I told our chemist and got a solvent based on H2O, H2O2 and H2SO4 that is really good in slightly removing the oxide. Thought I share that with you.

-branadic-

[David Hess]

I can also vouch for DeOxit products, everything we've used it on is fine and probably had the best success over other stuff.

Which ones?  DeOxit has so many products with nebulous properties and ingredients that I have no idea what anything they make is or does.

[helius]

I currently have some gear on my desk with pretty rusty copper binding post. Even Deoxit isn't strong enough to remove the oxide. So I told our chemist and got a solution based on H2O, H2O2 and H2SO4 that is really good in slightly removing the oxide. Thought I shared that with you.

Hydrogen peroxide and sulfuric acid is called piranha and is super corrosive to all organic materials. This is what those safety signs are made for:

[branadic]

The solvent is very light, so no real problem.

-branadic-

[SilverSolder]

I can also vouch for DeOxit products, everything we've used it on is fine and probably had the best success over other stuff.

Which ones?  DeOxit has so many products with nebulous properties and ingredients that I have no idea what anything they make is or does.

I use two of their products: 

Step 1)  Clean the switches with Deoxit D5
Step 2) Apply protectant/lubricant Deoxit Shield S5

I buy the spray cans,  then spray a little of each into a pair of little bottles so it can be precisely applied with a little cocktail stick or something like that.   Spraying gallons of the stuff all over the inside of the DUT is obviously not going to do anyone or anything any good.   Sometimes, the design of the equipment forces you to use the spray -  in those situations, I cover the surrounding areas with paper towel before spraying to do as neat a job as possible...

This two step treatment tends to last a long time.  I've used it on rotary encoders, pots, relays, wafer switches, slide switches, etc. etc.

However it is not a miracle cure for very tarnished metal.  Just the other day, I had to resort to cleaning some badly burned unobtanium relay contacts by lightly scraping and then burnishing them back to a shine using a jeweler's burnishing tool.  Followed by the Deoxit Shield S5, of course.  Looks beautiful, works perfectly, with low contact resistance.

[coppercone2]

How come there are no special polishing tools for this? It all seems crazy to do it chemically because i think the oxide will result in asparities and i dont think you can chemically remove them, you need mechanical cutting i.e. polish??

I think the chemicals leave a pitted surface. When i use my experiances with metal working, you never get a nice finish from electroylsis or acid oxide removal on copper or steel. You need to refinish it with different grades of sandpaper or if its good enough use different mesh sizes of rogues to shine the surface.

With something that needs to be very flat its different but i noticed in general the more you polish something after rust removal the less it rusts.

Even going over it with a wire wheel after chemical removal helps, but you really need to remove material down to the lowest pit and polish or lap.

Imo if you have a thin mound of metal on a surface it has more exposure to oxide per surface area vs volume so oxide grows on it and strains it or something and it causes shifts.

I wanna see electron microscope pictures of the effects of all this deoxit voodoo. Chemical polishing is hard to do (used in semiconductor industry, and it still requires lots of motion). It is against my knowledge of convenctional mechanical behavior.


Now chemical rust removal is a good first step because rust is a ceramic and the metal cutting toolslike polish, sandpaper, or metal brush is all similar or less hard then the oxode layer so unless you have a correct feed and speed to work under the oxide your cutting tools take a beating ( yes sandpaper and a grinding wheel are cutting the same as a mill, it makes microscopic metal coils), if you remove the oxide first your cutting tool wears less and maintains a better cutting edge (i.e. the grits of polish or sandpaper) so your surface finish is better because there is less deformation and more cutting. Since the cutting grits of polish or sand paper maintain a better rake angle for longer.

And the rust tends to absorb oil in its cracks so it cuts the sandpaper less if the metal is clean of it


All I can think of is that the de-oxit forms a conductive pesudometallic layer, similar to aluminum magnaplating, but with gold, to the thickness of the highest asparity (it must have a acceptable range of [ro], (surface finish) to work under). And if its not thick enough, and forms a mount over an asparity, thats where then 'pot cycling' comes into play, where you knock off the high point to get a acceptable conductive layer.

I would think that a re-polish is still superior.

https://www.finishing.com/133/65.shtml
https://en.wikipedia.org/wiki/Chromate_conversion_coating

[Conrad Hoffman]

A lot of things I want to clean/protect are inaccessible. Rotary switch wafers and digital encoder switches come to mind. It's chemicals or nothing. Better Things for Better Living Through Chemistry! (The old DuPont slogan)

[mvanocht]

The Keysight 34420A Nano Volt/Micro Ohm meter comes with a bottle of DeoxIT and recommends it's use on the Input Connector on P.7 of the manual:

"Because the meter uses connector contacts that are almost pure copper, they are
subject to oxidation. Oxidation can cause measurement errors. See page 276.
To help prevent the formation of oxides on the connector contacts, keep the
connector engaged whenever possible. After extended periods of time, it may be
necessary to treat the connector contacts. The recommended treatment uses
DeoxIT™[1] and a small bottle of DeoxIT was included with the 34420A. Use the
following procedure to apply DeoxIT to the connector terminals."

[SilverSolder]

It all seems crazy to do it chemically because i think the oxide will result in asparities and i dont think you can chemically remove them, you need mechanical cutting i.e. polish??

https://www.finishing.com/133/65.shtml
https://en.wikipedia.org/wiki/Chromate_conversion_coating

Using De-Oxit is not like dipping your equipment in phosphoric acid or anything like that - whatever this stuff is, it is very mild.  I suspect that in many cases, it is just washing off surface contaminants.  Certainly it is not strong enough to cut through seriously tarnished metal.

For example, EDC recommends it for use in their voltage reference/ voltage divider products.  If it did anything bad, we would surely know about it by now - there are so many people using it, for decades, that any ill effects would be known by now.

As Conrad says,  sometimes you can't take things apart. -  I bought an oscilloscope three years ago that had unresponsive rotary encoders.  I thought, "Let's just try de-oxit before ordering a batch of new ones".  -  Still haven't placed an order for new ones! 

Just a few weeks ago, I got hold of an old Genrad voltage divider.  Here, the problem was that the lubricant had become gummy and made it hard (almost impossible) to rotate the knobs.  The DeOxit D-5 liberally applied to the bushings freed it all up - without taking anything apart, even -  and I didn't have to worry about contaminating any of the beautiful silver switches or hand wound resistors with other products that are not specifically made to avoid damaging electronic components.

I also have the Stabilant 20 product that @Texaspyro mentioned earlier.  This works by creating "tunneling" opportunities for the current between bad/rough surfaces.  It does work well,  but I have found it more reliable to get the stuff thoroughly clean and protected with the Deoxit products, and perhaps use the Stabilant afterwards as extra insurance.

[coppercone2]

i had a can of it from ebay once, but it seemed like a temporary measure.

[cdev]

For cleaning and lubricating roller inductor I read that some very high end company that makes such tuners recommends "lubri-plate" which is a lithium grease based lubricant used for metal on metal situations. I found a deal on three small tubes of it - this was sold for people to use to lubricate their garage doors and garage door openers. I forget what I paid but it was very little. Anyway, it seems to have cleaned up the grit this tuner had on receive. (I don't transmit yet, not having either a license or hardware to do so)

But the lithium grease was a huge improvement over the gunk which had been used on it before.

[Moon Winx]

@Moon Winx

I've tried a couple of flavors of DeoxIt but it would sometimes leave a gummy residue.

That's interesting. Could You please tell us more details, observations?

Ethyl (non-denatured) alcohol is conductive but evaporates quickly. Deoxit, even the fast-dry versions, and non-conductive but take several minutes to evaporate. If you don't wait until it is completely gone before connecting your leads/connectors, you may leave a non-conductive film between the metals.

We've used the flushing DeoxIt and the quick-dry / no-drip versions and liked the quick-dry version at first, but noticed equipment coming back in for calibration a year later had a filmy-gooey coating on the terminals. We never had this problem with the ethyl alcohol. I can't say for certain it was the DeoxIt but it would be too much of a coincidence to believe otherwise.

Having said that, I still use it on our own equipment that have the LEMO 4-pin connectors. Those things get really nasty looking after awhile.

[martinr33]

If you have silver plated contacts, the silver restoring polishes do a good job. If you can put up with it, the silver plating cleaners also do a nice job on copper (of course, they leave a thin silver coat). "Silver dip" is the kind of thing you are looking for.

For battery contacts (there is a brand of alkaline cell that is pretty much guaranteed to corrode contacts) I use a tin plating solution. That one is definitely not for precision measurements.