Cleaning circuit boards?

I've got a magnetic apogee detector that got some ejection charge residue on it
due to a leak in the old electronics bay. What's the best way to clean it?
Reply to
RayDunakin
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Or the stiff Q-tips (not flimsy ones), such as those used in head cleaning kits at Radio Shack.
Formerly (back in the bad old days when we were allowed to be environmentally unsound ), we used liquid Freon or MEK.
David Erbas-White
Reply to
David Erbas-White
You can still get MEK at hardware stores if you look around a bit... some of the better-stocked OSH locations have it. (For most stuff I just use acetone, though... )
Freon TF (aka Freon 113) and similar materials are, alas, no longer available... Du Pont _does_ appear to have introduced "Ventrel XF", a chlorine-free HFC replacement.
-dave w
Reply to
David Weinshenker
Believe it or not, most electronic assemblies and circuit boards are mechanically rugged and waterproof insofar as cleaning is concerned. Water itself, even mild detergent, is not usually a problem. I've used water, alcohol, spray foam cleaners, and scrub brushes on everything from vacuum tube chassis, to computer motherboards, to precision test equipment modules. Being wet isn't really an issue, but proper drying and no residue are important.
Alcohol is a good solvent, but ask yourself where the dissolved material goes when the alcohol evaporates; into a thin film back on the device. Use lots of Q-tips if you go that route. I've seen alcohol remove ink markings (serial numbers!) on PCB's and components, so watch out for that.
Here's the initial prodedure we used for assembly and PCB cleaning at a military overhaul depot:
1. Wash under running water with foam cleaner (mild detergent) and soft bristle brushes. 2. Tap water rinse 3. Wash again. 4. Tap water rinse. 5. Distilled water rinse (submerged dip). 6. Dry in a 96 degree F drying oven for 24hrs.
Also, be conscious of static electricity issues when handling unmounted boards or components; the number one cause of damaged semiconductors.
Obviously, check with the manufacturer first if you have any doubts about cleaning materials or methods.
Reply to
Gary
Be carefull if it has a pressure sensor on it. I have no idea how attached the gel is thats inside the motorola ones so I simply dont get them wet.
RDH8
Reply to
Robert DeHate
Omigosh, I actually had a warning for barometric sensors in my draft post but seem to have edited it out.
Of course Robert is correct. Water is usually not a problem on the OUTSIDE of electronic components, but the INSIDES are a different matter. I wouldn't wet a gas pressure sensor without plugging/blocking the ports.
Thanks for the important observation.
Reply to
Gary
The best thing you can do is to conformal coat the card. This puts a protective surface between the card and the outside world. It will keep ejection gasses (and fingerprints) from corroding circuit traces, keep moisture from infiltrating parts, and help keep parts in place. Great stuff.
I found a spray can of conformal coat at my local Fry's. If there isn't a Fry's near you, you might be able to find it in some other store that caters to the electronics hobbyist.
The only trick to using conformal coat is to mask off those things that you do not want to coat before spraying: connectors and pressure sensor ports being the biggies. I expect a MAD wouldn't require much masking.
In a professional board shop there would be an inspection station that is dark except for low level UV light. The conformal coat fluoresces under UV so it can be inspected for complete coverage.
RayDunak > I've got a magnetic apogee detector that got some ejection charge residue on it
Reply to
David Schultz
Hence the implicit requirement for proper drying techniques, ie, the time in the drying oven.
On home projects, like a part-out of scrap electronics, I use a small electric space heater blowing into an insulated (or not) cardboard box.
A hair dryer on low works well for the quick drying of one or two assemblies.
Reply to
Gary

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