I have removed the sticky pungent liquid that has leaked from an electrolytic capacitor using cotton buds dipped in soapy water.
Access is difficult in the cramped PCB. Some of the corrosive liquid may remain in holes and under resistors, etc.
What should I use to flush out or 'neutralise' any remaining corrosive contamination that is inaccessible?
Many thanks,
Rudge
If you can free up the PCB and if there are no paper objects, IF cans or transformers, you may rinse it down with 100% volatile contact cleaner then distilled water. The cleaner will get the hydrophobic components, the distilled water will get the salts. Then use 91% isopropyl alcohol to remove any water, allow to dry overnight.
Otherwise, delete the distilled water and go from the cleaner to the alcohol. Use the cleaner sparingly so as to avoid thermal shock - which cracks traces.
Peter Wieck Wyncote, PA
dear friend donot use soap water it is corrosive,use thinner or isopropyl alchohole-available in chemical shop.but thinner is cheaper and available in paint shop ,
I, too, have had to mop up the goo left by an exploding electrolytic cap. Try finger nail polish remover, which is diluted acetone. If you don't have that, try isopropyl alcohol. In any case, once you've applied your household solvent of choice, and have cleaned the board to your satisfaction, do a final rinse with water or window cleaner using a towel paper, Q-tip or cotton ball to remove any remaining solvent. After this, blow compressed air over the printed circuit board or use a hair dryer (at a safe distance) to evaporate any remaining liquid.
Here's something to be mindful of: If the cap exploded and its innards have been sitting on the board for some time, there's some risk that a conductor trace/path has been eaten away. Inspect the board with a magnifying glass or hold it in front of a lightbulb (assuming the board is translucent). If you find a broken path, you can solder a small wire across the gap or fabricate a new path by installing a wire on the back of the board that connects the path's two end-points.
-Dave, K3WQ
snipped-for-privacy@drumheller.org wrote in news: snipped-for-privacy@u30g2000hsc.googlegroups.com:
"diluted" with what? It seems more like it's some oily material thinned with acetone.
The real question is; what is the electrolyte composed of?
acidic or alkaline?
then you would know what to use as a solvent/neutralizer.
-- Jim Yanik jyanik at kua.net
Doubtless some will disagree with me. I've had good results on mother boards with just water and dishwashing liquid.
We have tap water also de ionized and distilled water and have used them for a final rinse. I've been putting the board in a plastic pan completely submerged with water and detergent. I have access to a laboratory mixer that gently rocks the pan - in the old days with photography pans we used to put a pencil under the pan and rock it using the pencil as a fulcrum.
After about an hour of rocking left-right we turn the board, change the solution with fresh stuff and rock up-down for an hour - then two rinses in water - spray off the water with dry compressed air (we also use a vacuum oven if one is free in the lab to warm and pull vacuum on the board to evaporate the water). Standing on edge and air drying for a few days would probably be good enough.
Solvents? Isopropyl alcohol - Acetone is safe most of the time since boards are frequently de fluxed with acetone - but don't soak it for too long.
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There are a bunch of issues here. Several years ago, there was an epidemic of leaky caps. If one is bad, you may have others in the same condition. I've fixed several oscilloscopes by replacing about 150 caps. The goo creeps all over, underneath IC's, You MUST get it all out of there. Especially inside the via holes. It eats thru the plating and the internal connections open up.
I use "Simple Green" and a toothbrush to get off the oily stuff, water rinse, then 99% alcohol to get off the simple green and the organic stuff. Blow dry, use air compressor to get enough force to blow moisture out from under stuff, bake, install new caps.
Had one laptop that finally came back to life on the third iteration of the cleaning process. The goo is conductive and you can't see it. mike
-- Return address is VALID! Bunch-O-Stuff Forsale Here: http://mike.liveline.de/sale.html
I don't know what it's diluted with--and I don't care. All I know is that its smell is not as pungent as the pure stuff you can get from the paint department at Home Depot.
Acidic or alkaline? Does knowing the specific chemical type really matter in a practical sense? I merely suggested he try common household solvents; chances are one of them will work. When he's done using whatever removed the electrolyte, he should rinse it with something safer and then dry it. This by no means a professional approach, but it's worked for me.
-Dave
That's a good process that I use frequently. However, sometimes I need to use a can of "flux remover" spray and that works too.
For aluminum electros, the electrolyte is AFAIK always alkaline. Tantalum electros I am not so sure about.
For cleaning up alkaline goo, diluted vinegar (start with distilled, white vinegar) which is a mild aqueous solution of acetic acid, can be helpful. However, one would still want to end with flushing with copious amounts of non-mineral containing water (e.g., distilled, not stuff that has been "softened", nor hard water), followed by drying, perhaps with an isopropyl rinse following the water rinse to aid in the drying.
But it depends on whether there are other things that could be marred or damaged by any of these treatments.
The safest, albeit most work, is distilled water clean up followed by blown air, non-heat or mild heat, drying.
snipped-for-privacy@drumheller.org wrote in news: snipped-for-privacy@h2g2000hsg.googlegroups.com:
Nail polish remover will leave some residue of it's own. It's for *fingernails*,after all.
and if you can get away with using something safer than acetone,a flammable solvent,or harsh chemical,the better.
Yes,you want to -neutralize- the electrolyte. Solvents will also attack other items on the board.(while you are cleaning the electrolyte off the board.) Solvents also SPREAD the corrosive electrolyte around,to be wicked up by something else..
-- Jim Yanik jyanik at kua.net
default wrote in news: snipped-for-privacy@4ax.com:
I've never heard of epoxy-glass PCBs being cleaned/defluxed with acetone;it would attack the epoxy.
-- Jim Yanik jyanik at kua.net
Ken Layton wrote in news: snipped-for-privacy@n76g2000hsh.googlegroups.com:
A good final cleaning is running a PCB thru the auto dishwasher using a gel-type detergent(no rinse agent),then drying.
-- Jim Yanik jyanik at kua.net
It might if the epoxy isn't cured completely - that never seems to be the case though. Acetone should be deadly to polystyrene caps too - but we never use them so I wouldn't know. Maybe it will attack the boards if left for too long.
One production facility I worked at used trays of acetone or trichloroethane to soften the flux then lay a (stiff - like you find in restrooms) paper towel over the connection side and scrub with a stiff brush - the dissolved flux would be picked up by the paper towel.
Leave the board in for too long and sometimes the "solder mask" coating would begin to dissolve and take any printing with it.
But plain detergent and water seems to be the solvent/solution for leaky electrolytics - a rinse with acetone or alcohol may help to dry the board faster - never use it myself.
Old photo darkroom technique was to squeegee the freshly developed film with a sponge and alcohol to promote fast drying and eliminate water spots from minerals in the water.
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default wrote in news: snipped-for-privacy@4ax.com:
Which was it? there's a difference. "trays" of acetone would evaporate quickly,put dangerous ignitable vapors into the air,and be a significant safety hazard. Respirators would HAVE to be worn. OSHA would have a fit. One spark could blow the place.
I *seriously* doubt it was acetone.
I STILL never heard of anyone rinsing PCBs with acetone.
-- Jim Yanik jyanik at kua.net
It was both at one time or another. Osha did have a fit but over the Trichloro for health hazards from breathing, we started using a hood and ventilator. The trays weren't open to the air - they had covers and the wash station was in a sort of garage where we stored bins of parts - lot of ventilation and lot of space.
It was a sort of "industrial module" the garage was probably intended as shipping and receiving but we occupied several modules and used the garage for a parts store and wash area.
Hey! people do dumb things all the time. Osha gets involved if someone speaks out or they have an accident they can't cover up.
I worked in a lab where they moved the ultrasonic cleaners into a cabinet under a lab table near a hood. Then they moved the vacuum pump into the cabinet.
All because they didn't like the noise . . .
That was the case until someone found a protocol that called for "filtering" ether to remove the solvent and recover the particles of compound. Some idiot decides to use vacuum filtration - pumping the ether vapor into the cabinet with the vac pump and ultrasonic cleaner.
The ultrasonic cleaner used a voltage tripler and several large vacuum tubes and worked without isolation from the 120 volt mains. Great ignition source . . .
These were "graduate chemists" -
I closed the vacuum valve, and opened the cabinet. The chemist running the procedure was livid with rage - he thought I should be fired on the spot for interfering with his project. It was netting the company 50K for a weeks work.
The smell was strong and I was afraid if I switched off the pump or cleaner I'd make the spark to touch it off. I told everyone to get out and set off the fire alarm. They lost a lot of money that day. I damn near lost my job over it, and probably saved a few lives.
Industry doesn't always consider safety.
Case in point: heating 6 gallons of water in a closed system with a
500 PSI burst pressure, with a 8KW heater and no safety valve - ("a valve might allow bacteria to infiltrate the system"). How long does it take 8KW to heat six gallons to boiling? Five - ten minutes? That would be devastating but what happens if the heating elements get to white hot and THEN water is introduced into the heater?Case in point: Using a class C oven for Class A vapor - the CEO? "Couldn't we just get them to sign a waiver and pay them a little more?" (fortunately the lawyers nixed that one - I was supposed to sign off on it)
Case in point: DI water system goes down - we are testing drugs that people will use. Protocol calls for reagent grade water - we are almost using tap water, but the lab manager (making a seven figure salary) won't spring for the cost of importing distilled water.
I had a reputation as a "Prima Donna" (OK with me - prima donnas are paid for their singing, not their personalities) I was not the safety officer - I was the "R&D engineer."
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