what chemical to clean the pcb after leaking capacitors - Page 1
Forum section: electronics / beginners

author: Kjelt
author_rank: Super Contributor
timestamp: May 12, 2017, 08:05:09 pm
content: 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 withlaquer 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 ?Quote from: Electro Detective on May 12, 2017, 01:23:21 am

author: Zero999
author_rank: Super Contributor
timestamp: May 12, 2017, 08:13:37 pm
content: 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.

author: Benta
author_rank: Super Contributor
timestamp: May 12, 2017, 08:35:20 pm
content: 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.

author: wraper
author_rank: Unknown
timestamp: May 12, 2017, 08:40:34 pm
content: 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.

author: helius
author_rank: Super Contributor
timestamp: May 12, 2017, 08:50:41 pm
content: 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.

author: wraper
author_rank: Unknown
timestamp: May 12, 2017, 09:02:32 pm
content: Quote from: helius on May 12, 2017, 08:50:41 pmAlcohols are only barely polar, therefore very ineffective. For example, try dissolving table salt in IPA.

author: macboy
author_rank: Super Contributor
timestamp: May 12, 2017, 09:52:28 pm
content: Quote from: wraper on May 12, 2017, 08:40:34 pmI 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).

author: Kjelt
author_rank: Super Contributor
timestamp: May 12, 2017, 10:54:38 pm
content: 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?

author: Electro Detective
author_rank: Super Contributor
timestamp: May 13, 2017, 07:28:33 am
content: Whichever way works, depends on the job at handand whether a water nuke will affect adjacent components, wash away stickers etcMy 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 drierLazy 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 twoferPut 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 sitor worry about board cremation in an ovenFor 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

author: David Hess
author_rank: Super Contributor
timestamp: May 13, 2017, 03:47:48 pm
content: 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.

author: Kjelt
author_rank: Super Contributor
timestamp: May 13, 2017, 04:02:59 pm
content: NaHCO3 Aka Bakingpowder is a good base for neutralizing acid and not toxic or aggressive.Thanks Thats a good addition to the process.

author: helius
author_rank: Super Contributor
timestamp: May 13, 2017, 04:51:11 pm
content: 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.

author: David Hess
author_rank: Super Contributor
timestamp: May 13, 2017, 06:10:24 pm
content: 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.

author: Seekonk
author_rank: Super Contributor
timestamp: May 13, 2017, 06:29:12 pm
content: Didn't anyone watch "My Big Fat Greek Wedding" Windex works for everything.

author: Electro Detective
author_rank: Super Contributor
timestamp: May 14, 2017, 01:27:15 am
content: Quote from: Seekonk on May 13, 2017, 06:29:12 pmsecond only to WD40 and cola

author: Muxr
author_rank: Super Contributor
timestamp: May 14, 2017, 02:41:01 am
content: 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.

author: David Hess
author_rank: Super Contributor
timestamp: May 14, 2017, 02:58:10 am
content: Quote from: Muxr on May 14, 2017, 02:41:01 amI 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.

author: P90
author_rank: Frequent Contributor
timestamp: May 14, 2017, 04:02:35 am
content: Quote from: helius on May 12, 2017, 08:50:41 pmI 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...

author: MonarkeIV
author_rank: Contributor
timestamp: August 27, 2023, 11:26:11 am
content: 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!

author: DavidAlfa
author_rank: Super Contributor
timestamp: August 27, 2023, 11:48:35 am
content: 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, butstill 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.

author: u666sa
author_rank: Frequent Contributor
timestamp: August 27, 2023, 04:23:48 pm
content: Quote from: Kjelt on May 12, 2017, 08:05:09 pmBenzine..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.

author: Wallace Gasiewicz
author_rank: Super Contributor
timestamp: August 27, 2023, 07:13:34 pm
content: 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.

author: Jeff eelcr
author_rank: Frequent Contributor
timestamp: August 27, 2023, 10:23:57 pm
content: Kjelt I have used tap water, Comet clenser and a toothbrush mainly, in the summersetting them outside in the sun here will dry them quickly.Scraping on badly corroded areas is required and finish with a cleaner/lube on mostPC boards. Rarely will I have to remove other parts and in winter I use a heat gun todry.Jeff

author: donlisms
author_rank: Frequent Contributor
timestamp: August 28, 2023, 12:54:16 am
content: 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!

author: Kjelt
author_rank: Super Contributor
timestamp: August 28, 2023, 12:14:56 pm
content: Thanks people but this is a topic from 2017, now a zombietopic

author: Terry Bites
author_rank: Super Contributor
timestamp: August 30, 2023, 07:41:08 am
content: I think Mr C would say if he was using acetone or ipa instead of laquer thinners.Have a look at this evil cocktail.

author: David Hess
author_rank: Super Contributor
timestamp: August 30, 2023, 02:50:04 pm
content: Acetone and isopropyl alcohol are at least miscible with water.Aluminum electrolytic capacitor electrolytes are typically something like boric acid and ethylene glycol so a majority of the cleaner should be simple water. The components of lacquer thinner are less useful here.

author: helius
author_rank: Super Contributor
timestamp: August 30, 2023, 06:45:20 pm
content: Lacquer thinner is made for one thing only: spraying nitrocellulose lacquer coatings.The process was invented in the 1920s and relies on multiple solvents with varying weights. The lacquer-solvent mixture is super thin as it exits the spray nozzle, and enough solvent evaporates in flight to make it significantly thicker by the time it hits the workpiece. This makes it possible to spray vertical surfaces without runs.As I said on page 1 it has no application to electronics.

author: swanng
author_rank: Newbie
timestamp: January 12, 2025, 11:46:40 pm
content: I have been using methylethylketone (MEK) for over 30 years with no problems (aside from the smell). It evaporates very fast, yet cleans PCB's FAR better than any alcohol.

author: helius
author_rank: Super Contributor
timestamp: January 14, 2025, 07:17:10 pm
content: MEK is very similar to acetone in its effects. They both can absorb into plastic chip carriers, which could cause problems, as well as removing any markings, whether they are inked or laser marked. Indeed, acetone (or MEK) is a good method to detect fake black-topped chips because the black coating will get rubbed off. Removing silkscreen print is another possible effect.The question in choosing a solvent is what type of soil do you need to remove, and how powerful a cleaning is required? Using a solvent that is "FAR better" is not necessarily a good thing because it will remove more material than desired.The other part of cleaning is technique. Just rubbing some solvent around until it evaporates won't remove any soil! Where did you expect it to go? Cleaning must transfer the soil to a waste receptacle of some kind, either by flushing with large amounts of solvent so it runs off into the bin, or by agitating with a cellulose towel so the soil moves into the towel. This is why fast-evaporating solvents are usually a disadvantage for cleaning circuit boards.

author: jpanhalt
author_rank: Super Contributor
timestamp: January 14, 2025, 07:53:44 pm
content: Acetone, MEK, IPA and such are great solvents for some things, but an aluminum electrolytic capacitor (assumed) or any other electrolytic cap. contains an electrolyte. That is, something ionic, and none of those solvents are great for ionic substances. There are exceptions for some alcohols.FromWikipedia:QuoteBorate with vicinal alcohols (like ethylene glycol) is one of the exceptions. IPA is not a vicinal alcohol. In any event, a water-based cleaner for flux should work great. You can make you own from may household cleaners.