Favorite PCB cleaners

I'm about to embark on some designs where there'll be resistors in the ballpark of tens of megaohms, and I've been advised that with values that high, oil from one's skins and other typical contaminants can be enough to noticeably shunt the resistors and thereby introduce measurement errors. The test prototypes will also be hand-soldered, so there'll likely be some flux remaining on the boards as well.

Traditionally I've just cleaned boards with things like isopropyl alcohol and (ahem :-) ) Goo Gone, but for really good cleaning... does anyone have additional suggestions?

(I'm told that one of the biggest problems with oils that that they can change radically over time in terms of their impedance; you might calibrate a system one day, and find it woefully out of spec the next.)

Note that my "cleaning machinery" is limited to a couple of ultrasonic cleaners and dishwashers -- no fancy vapor phase degreasers around here. (Although if anyone knows of some relatively inexpensive machinery that's just the cat's meow, it is possible I could buy something.)

Thanks,

---Joel

Reply to
Joel Koltner
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I use "Tronic Kleen" (aliphatic hydrocarbon, tetrafluorethane). But the real trick is to never let skin oils get on there in the first place.

Asian companies seem to heed that strategy a lot. When I opened my Instekl scope there were zero finger prints or anything in there. They must have worn gloves.

--
Regards, Joerg

http://www.analogconsultants.com/
Reply to
Joerg

This should work fine. We do some work with things that need

500 V bias, and must have leakage under ten nA, so they have to be quite clean. A 10 minute bath in pure alcohol in ultrasonic cleaner, then scrub sensitive areas with toothbrush and finally rinse with clean alcohol and blow dry with compressed air works quite well.

Industrial alcohol from the hardware store is better than the drugstore-grade stuff sold as "rubbing alcohol".

Jon

Reply to
Jon Elson

I got a couple of bottles with bio ethanol. It works excellent for cleaning boards. I have official 'flux remover' but the ethanol works much better.

--
Failure does not prove something is impossible, failure simply
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Reply to
Nico Coesel

Great, thanks.

Would you chance using an oil-free (permanently lubricated) air compressor for that air? Or stick to air-in-a-can?

Reply to
Joel Koltner

ballpark of tens of megaohms, and I've been

contaminants can be enough to noticeably

prototypes will also be hand-soldered, so

Naphtha, now only available as 'Coleman Camp Fuel' in my area. It is extremely flammable and volatile so use upwind outdoors, very far away from open flame or sparks.

This stuff is the best PCB cleaner ever.

Wear rubber gloves because it will dissolve the oil on your skin, causing cracking. DAMHIKT.

--Winston

Reply to
Winston

Rosin flux, you don't need to clean it, use whatever solvent you like. We did have issues with other fluxes, the water soluble ones I think.

George H.

Reply to
George Herold

Ordinary board handling won't be a problem at megohms, and barely a problem at gigohms. Just don't use a no-clean or water-soluble flux, as that can be conductive and hygroscopic. Water-soluble is OK if you clean it really well.

I soldered a couple of wires to a PC board, to two adjacent vias leading to adjacent SO8 pins. All full of rosin flux and deliberate fingerprints, I'm measuring about 2e13 ohms.

Maybe I'll clean it and see what happens.

--
John Larkin, President
Highland Technology, Inc
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Reply to
John Larkin

o

One could worry that 'cleaning' the rosin with the wrong stuff could make it worse.

George H.

ed text -

Reply to
George Herold

Yea, real well, Ionized water , a full sized washer, filters, yada yada. Stick to rosen core for small runs. Let the big assembly houses use no-clean.

Cheers

Reply to
Martin Riddle

I would use heated air. Alcohol sucks water.

Water based flux gave me problems when it was not completely gone.

Greg

Reply to
gregz

Best product in the world for clean, zero residue work is called Ensolv. Not cheap.

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Reply to
Chieftain of the Carpet Crawlers

We have got leaky boards from big assembly houses that use water processing, apparently because they didn't really blast under surface-mount parts. Tens of megohms. Water-wash flux is very conductive, nasty stuff. I bought a WaterPic and some DI water and had The Brat re-clean and bake the boards.

On some of our analog-critical boards, we insist on rosin flux and solvent clean. Most assembly houses no-bid that. Luckily, we can do that in-house.

--
John Larkin, President
Highland Technology, Inc
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Reply to
John Larkin

Your IQ has to be at least 30 to spout that gem.

Even at the 'drugstore', IF one buys the 91% stuff, one gets good IPA.

If you buy the 70% stuff, all you get is the 70% stuff. It doesn't matter where the source is.

The moniker on the label doesn't mean anything. The only difference is that the medical grade stuff was refined on sterile, certified equipment.

The industrial stuff could have been evaporated in the same device they did cleaning fluid in the previous shift.

Reply to
FatBytestard

ballpark of tens of megaohms, and I've been

contaminants can be enough to noticeably

prototypes will also be hand-soldered, so

It will also dissolve the shrink wraps on your EL caps and various other polymers which may or may not be part of your assembly.

Use with extreme caution, and usually AFTER you have a modicum of familiarity with how solvents function.

Reply to
Chieftain of the Carpet Crawlers

BULLSHIT.

More bullshit. It cuts easily with standard IPA, and is untouched by some others. One must be careful which solvents one places on a PCB assembly. It is more than FR4 and resistors. Solvents can *melt* things.

You showing yourself not knowing is a very big tell about the extent of your grasp of the entire realm.

Reply to
Chieftain of the Carpet Crawlers

Which makes one wonder why your suggestion was "use any solvent".

Make up your mind.

Reply to
Chieftain of the Carpet Crawlers

I swished it in the tank of our PCB cleaner. It's shut off for the weekend so I couldn't do the whole cycle.

Pinned the needle on the 1e14 range!

John

--
John Larkin, President
Highland Technology, Inc
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Reply to
John Larkin

IPA can leave white residue. For home use, without buying exotica, acetone is a great flux cleaner. Just don't trash any parts or plastic.

--
John Larkin, President
Highland Technology, Inc
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Reply to
John Larkin

Don't believe his bullshit. Some of the drug store cheap stuff has ingredients in it to prevent skin from drying out. Watch out for esters added like wintergreen oil, or sometimes even lanolin.

Reply to
miso

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