Author Topic: what chemical to clean the pcb after leaking capacitors  (Read 19751 times)

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Offline KjeltTopic starter

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what chemical to clean the pcb after leaking capacitors
« on: May 12, 2017, 08:05:09 pm »
I was reading the topic below, not wanting to hijack it opened this topic.
In the youtube video, Carlson tells that he cleans the pcb with laquer thinner???
I have no idea what that exactly is, we have paint thinner here in Holland but I do not think that is the same stuff.
Anyway I always clean contaminated pcbs just with IPA, because they do not fit in my ultrasound cleaner.

What do you use to clean the pcb after some leaking capacitors ?

This looks like a better deal than trial by fire, I haven't tried it yet  :-//

Mr Carlsons Lab on youtube btw  :-+


 

Offline Zero999

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Re: what chemical to clean the pcb after leaking capacitors
« Reply #1 on: May 12, 2017, 08:13:37 pm »
Firstly I'd use IPA (at work) or if nail varnish remover at home, then I'd wash it in a detergent, followed by another dose of IPA (at work) or just rinse it with hot water and leave it to dry. Where I used to work we'd rinse it with deionised water but where I am now we don't do anything for commercial use so don't bother.
 

Offline Benta

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Re: what chemical to clean the pcb after leaking capacitors
« Reply #2 on: May 12, 2017, 08:35:20 pm »
Dunno what he means by "lacquer thinners", but I suspect something with acetone. Forget it.
The only chemical to use on electronics is IPA. Demineralized water with a drop of detergent for greasy spots.
Nothing else.


 

Online wraper

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Re: what chemical to clean the pcb after leaking capacitors
« Reply #3 on: May 12, 2017, 08:40:34 pm »
Wash with water and detergent. Then rinse with clean water. After that best would be to rinse with distilled water. If possible, blow out any remaining water with compressed air and then dry well. IPA, acetone and other organic solvents are nearly useless against leaked electrolyte.
 

Offline helius

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Re: what chemical to clean the pcb after leaking capacitors
« Reply #4 on: May 12, 2017, 08:50:41 pm »
In North America "lacquer thinner" is a product with very strong (mostly nonpolar) solvents like toluene, acetone, and xylene. It has no place in an electronics shop.
Electrolyte in capacitors is primarily a polar material, so polar solvents (water, methanol, ethanol, isopropyl alcohol) are needed to remove it.
 
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Online wraper

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Re: what chemical to clean the pcb after leaking capacitors
« Reply #5 on: May 12, 2017, 09:02:32 pm »
so polar solvents (water, methanol, ethanol, isopropyl alcohol) are needed to remove it.
Alcohols are only barely polar, therefore very ineffective. For example, try dissolving table salt in IPA.
« Last Edit: May 12, 2017, 09:04:52 pm by wraper »
 
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Offline macboy

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Re: what chemical to clean the pcb after leaking capacitors
« Reply #6 on: May 12, 2017, 09:52:28 pm »
Wash with water and detergent. Then rinse with clean water. After that best would be to rinse with distilled water. If possible, blow out any remaining water with compressed air and then dry well. IPA, acetone and other organic solvents are nearly useless against leaked electrolyte.
I agree 100%
I would use distilled water throughout the process to reduce contamination and because it is a better solvent, being free of any already dissolved salts etc.. It is cheap here, gallon (4 l)  for $1 to $2.
I also blast with very clean very dry air (0.01 micron filtered and desiccant dried).
 

Offline KjeltTopic starter

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Re: what chemical to clean the pcb after leaking capacitors
« Reply #7 on: May 12, 2017, 10:54:38 pm »
Ok thanks , washing with demi-water sounds like a good idea.
Afterwards is anybody doing some drying in an oven at 110C or smething like that?
if all the electrolytic capacitors are removed anyway there will be no harm in it?
 

Offline Electro Detective

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Re: what chemical to clean the pcb after leaking capacitors
« Reply #8 on: May 13, 2017, 07:28:33 am »
Whichever way works, depends on the job at hand
and whether a water nuke will affect adjacent components, wash away stickers etc

My current fav is first rinse with warm water and slow soft brush, then warm water and mild detergent,
the final rinse should be warm distilled water (keep that last water for next time if fairly clean, saves money)

After that, put the board on a towel and use a hair drier

Lazy way: put the board in an open carton box orientated on the floor so you can point an electric fan heater into it (at the lowest HEAT setting),
 at a safe enough distance to get lots of hot air all around the board, and warm up the workshop lab and pets as well, nice twofer   ;D
Put something under the board to raise it and get hot air going everywhere at an equal rate in the box.
It's easier to do than it sounds, gets a tedious job done fast and safe, difficult to balls up, and you don't have to baby sit
or worry about board cremation in an oven  :-[

For suspected pockets of hidden moisture, I just blast with a no residue contact spray cleaner,
it pushes any water out and dries in seconds, job done    :-+

« Last Edit: May 13, 2017, 07:50:33 am by Electro Detective »
 

Offline David Hess

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Re: what chemical to clean the pcb after leaking capacitors
« Reply #9 on: May 13, 2017, 03:47:48 pm »
The electrolyte is acidic typically using things like boric acid and ethylene glycol so distilled, deionized, or reverse osmosis water is the way to go.  For the first soak and scrub after removing the bad capacitors, I would use hot water with some ammonia added to help neutralize the acid but I am sure someone can suggest something better than ammonia.  Then a couple more hot water soaks following by an air compressor and baking out the board.

I would not bother with any solvents for this other than water.
 

Offline KjeltTopic starter

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Re: what chemical to clean the pcb after leaking capacitors
« Reply #10 on: May 13, 2017, 04:02:59 pm »
NaHCO3 Aka   Bakingpowder is a good base for neutralizing acid and not toxic or aggressive.
Thanks Thats a good addition to the process.
 

Offline helius

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Re: what chemical to clean the pcb after leaking capacitors
« Reply #11 on: May 13, 2017, 04:51:11 pm »
When using a base the important criteria is whether it reacts to form water soluble salt adducts. Generally acid+base=salt, but some salts are relatively insoluble.
 

Offline David Hess

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Re: what chemical to clean the pcb after leaking capacitors
« Reply #12 on: May 13, 2017, 06:10:24 pm »
That is actually why I prefer ammonia to sodium bicarbonate for this.  There are lots of carbonate salts with very low solubility but few ammonium salts.  The various metal hydroxides produced are soluble in a base like ammonia so wash away.

Also residual ammonia will be driven off as a gas during bake out unlike sodium bicarbonate which will be left behind.

I have had more problems with sodium bicarbonate than ammonia but I would use either in preference to just water on the initial cleaning.

 

Offline Seekonk

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Re: what chemical to clean the pcb after leaking capacitors
« Reply #13 on: May 13, 2017, 06:29:12 pm »
Didn't anyone watch "My Big Fat Greek Wedding"   Windex works for everything.
 

Offline Electro Detective

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Re: what chemical to clean the pcb after leaking capacitors
« Reply #14 on: May 14, 2017, 01:27:15 am »
Didn't anyone watch "My Big Fat Greek Wedding"   Windex works for everything.

second only to WD40 and cola  ;D
 

Offline Muxr

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Re: what chemical to clean the pcb after leaking capacitors
« Reply #15 on: May 14, 2017, 02:41:01 am »
Yeah anything as strong as Acetone is not a good idea. I would imagine lacquer thinners fall in this category. I have some for extreme cases, but in my experience they are more trouble than it's worth. A lot of components and plastics on the PCB can be attacked and ruined by such a strong solvent. Usually with enough patience IPA should be all you need.

If you need to clean a lot of boards often then perhaps invest in ultrasonic cleaners and ultrasonic cleaning solutions.
 

Offline David Hess

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Re: what chemical to clean the pcb after leaking capacitors
« Reply #16 on: May 14, 2017, 02:58:10 am »
If you need to clean a lot of boards often then perhaps invest in ultrasonic cleaners and ultrasonic cleaning solutions.

I have a couple of older multimeter boards that I cleaned with my ultrasonic cleaner using dilute IPA and a little bit of detergent and the markings came off of the plastic packages.  The boards came out super clean and new looking.
 
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Offline P90

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Re: what chemical to clean the pcb after leaking capacitors
« Reply #17 on: May 14, 2017, 04:02:35 am »
In North America "lacquer thinner" is a product with very strong (mostly nonpolar) solvents like toluene, acetone, and xylene. It has no place in an electronics shop.
Electrolyte in capacitors is primarily a polar material, so polar solvents (water, methanol, ethanol, isopropyl alcohol) are needed to remove it.



I agree, I try to stay away from those strong solvents. Also, they melt most plastics.
Most of the  time distilled water, dishwashing detergent, a toothbrush, followed by compressed air does the job...
 

Offline MonarkeIV

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Re: what chemical to clean the pcb after leaking capacitors
« Reply #18 on: August 27, 2023, 11:26:11 am »
Seems Mr. Carlson has a Cartman "Respect My Authoritah" attitude on most everything.  Lacquer thinner will probably remove the silk screened part designations too.

I know for leaky NiCad batteries a 50/50 solution of White Vinegar and Distilled water is recommended to neutralize the electrolyte.

Mr. Carlson in a video about Maas-Rowe Carillon amplifiers claimed that they were installed "in the tower exposed to the weather".  Seems he doesn't understand how a 70.7v systems works either!  |O

Don Resor
Los Angeles
 

Offline DavidAlfa

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Re: what chemical to clean the pcb after leaking capacitors
« Reply #19 on: August 27, 2023, 11:48:35 am »
The corrosion will go away with white vinegar.
Desolder any nearby components, the acid will have leaked below them, hidding more potential damage, also the vinegar won't seep below them and clean properly.
Most will get dissolved by the vinegar in seconds, creating some foam and bubbling, usually 5-10 minutes is more than enough to remove everything.
DO NOT leave it in for hours, the vinegar is a weak acid, but still an acid, will end causing more damage if left for too long.

Rinse with distilled water and finish with IPA.
Use a fiberglass pen to finish any remaining damage, it's a mild abrasive that will hardly damage any traces unless you use it with extreme brutality.
It'll wipe away the damaged solder resist leaving a shiny finish. You can clean with IPA and apply a new resist coat for best result.
« Last Edit: August 27, 2023, 11:59:06 am by DavidAlfa »
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Offline u666sa

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Re: what chemical to clean the pcb after leaking capacitors
« Reply #20 on: August 27, 2023, 04:23:48 pm »
What do you use to clean the pcb after some leaking capacitors ?

Benzine..

Now there are different brands -- based on your market. Not all brands are good.

I use this.




P.S. thinner is an option. But no thank you. You need hand protection, you need breath protection, you need eye protection, and then you need to wash it down with something else, like alcohol. No thanks.
P.S.S. benzine or pure gasoline without detergents is the original cleaner. It was sold in pharmacies before cars went viral. Now it can be found at your local hardware store.   
« Last Edit: August 27, 2023, 04:29:30 pm by u666sa »
 

Offline Wallace Gasiewicz

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Re: what chemical to clean the pcb after leaking capacitors
« Reply #21 on: August 27, 2023, 07:13:34 pm »
There was a very successful repair guy who specialized in Kenwood Ham Radios. He put filthy boards and boards with both electrolyte damage and acid solder damage into his dishwasher. This worked great till his wife put a stop to the practice.These were thru hole boards.
 

Offline Jeff eelcr

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Re: what chemical to clean the pcb after leaking capacitors
« Reply #22 on: August 27, 2023, 10:23:57 pm »
  Kjelt I have used tap water, Comet clenser and a toothbrush mainly, in the summer
setting them outside in the sun here will dry them quickly.
Scraping on badly corroded areas is required and finish with a cleaner/lube on most
PC boards. Rarely will I have to remove other parts and in winter I use a heat gun to
dry.
Jeff
 

Offline donlisms

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Re: what chemical to clean the pcb after leaking capacitors
« Reply #23 on: August 28, 2023, 12:54:16 am »
Maybe I'm too far off the track, but let's not forget that Tektronix published an article back in the day, explaining how they cleaned oscilloscopes that came in for service, in a spray booth with detergent and water!
 

Offline KjeltTopic starter

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Re: what chemical to clean the pcb after leaking capacitors
« Reply #24 on: August 28, 2023, 12:14:56 pm »
Thanks people but this is a topic from 2017, now a zombietopic  ;)
 


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