Cleaning capacitor goop from PC board
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I have a board (not an Elecraft product!) which has several SMD electrolytics that have
failed, leaking brown, corrosive goop. The board is hard to find and expensive. I am going to try to fix it. Question: how do you clean the brown capacitor goop off the board? Some of the traces may be corroded, but I can't tell without getting this stuff off! And I don't want to damage them by scraping. -- Vic, K2VCO Fresno CA http://www.qsl.net/k2vco/ ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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My daughter works in archaeological artifact conservation, and deals regularly with issues of removing unknown substances from an artifact. The standard process in such cases is to start with the least-harsh solvents (water, then alcohol, then Goof-off, for example). Before you use any solvent on the affected part of the board, test to see if it will damage the board by putting a small amount on a q-tip and dab, then rub, on a corner of the board where it won't matter if the solvent damages traces or the non-trace areas. If it's going to damage the board, it will be apparent pretty quickly. rinse away any corrosive solvent with something known NOT to be corrosive (e.g. water).
The brown goop could contain a number of different chemicals, including weak acids such as boric acid and organic compounds such as glycol, so there's no single solvent that can be identified as guaranteed to be effective. I would try, in the specified order, water, alcohol, and then Goof-Off (which will dissolve many organic compounds) AFTER verifying that they won't corrode the circuit board itself). Lew K6LMP On Dec 25, 2010, at 11:04 PM, Vic K2VCO wrote: > I have a board (not an Elecraft product!) which has several SMD electrolytics that have > failed, leaking brown, corrosive goop. The board is hard to find and expensive. I am going > to try to fix it. > > Question: how do you clean the brown capacitor goop off the board? Some of the traces may > be corroded, but I can't tell without getting this stuff off! And I don't want to damage > them by scraping. > -- > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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In reply to this post by Vic K2VCO
Hello Vic,
I work in electronics manufacturing so cleaning of PCBAs is something I know a little bit about. Without knowing exactly what the goop is, I would recommend the following: 1) Gently scrape off as much of the material as possible using a soft scraping tool. I recommend a wooden popsicle stick. The key here is to not damage anything. Be GENTLE. 2) Once you have most of the goop cleaned off, I recommend using alcohol to remove any remaining residue. You can use store bought Isopropyl alcohol but the problem is that the stuff you buy in a store is only 70%...with the remaining 30% being water. A much better thing to use is to buy some Ethyl alcohol. Go to your local liquor store and buy a pint of grain alcohol. Brand name around here is "Everclear". This is 95% Ethyl alcohol...about as high as you can get outside of a chemistry lab. Alcohol is naturally hygroscopic (absorbs water) so you'll never get 100%. 3) Use the alcohol liberally, flooding the area to be cleaned. If its near the edge of the board, tilt the board so that most of the alcohol runs off into a bowl. What you want to do is wash the alcohol over the goop and let the residue flow off of the board instead of getting trapped under other parts. 4) Use a soft brush, like a clean toothbrush, in a circular motion to get the remaining part of the board really clean. Soak up any remaining alcohol with paper towel, getting as much off as possible. 5) Depending on how much crud you have to remove, you can give a final rinse with some distilled or de-ionized water. i wouldn't use tap water. The water won't hurt most electronics...we use water to clean PC boards all the time. You want to keep the water away, alcohol too, from any parts that are not sealed like switches, connectors and relays. Normal surface mount components are fine. 6) Finally, soak up as much of the remaining liquid with more clean paper towels and gently dry the area of the board with a little warm air. A hair dryer is ideal. Don't go overboard with the heat...you definitely don't want to reflow the solder :)) Once you have the circuit traces exposed you'll be able to assess any corrosion or damage. This part will be another story depending on what repairs you have to make. Finally, you can drink the remaining **unused** Ethyl alcohol...not Isopropyl :)) Just be careful...it's strong!! On 12/26/2010 1:04 AM, Vic K2VCO wrote: > I have a board (not an Elecraft product!) which has several SMD electrolytics that have > failed, leaking brown, corrosive goop. The board is hard to find and expensive. I am going > to try to fix it. > > Question: how do you clean the brown capacitor goop off the board? Some of the traces may > be corroded, but I can't tell without getting this stuff off! And I don't want to damage > them by scraping. -- 73, Gary K9GS Check out K9NS on the web: http://www.k9ns.com Greater Milwaukee DX Association: http://www.gmdxa.org Society of Midwest Contesters: http://www.w9smc.com ************************************************ ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
Re: Cleaning capacitor goop from PC board
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I buy 90% isopropyl alcohol at Wal*Mart and use it for PCB cleaning. I
think it's a couple dollars for a quart bottle, available in the drug section. I've also found 90% at most drug stores or supermarkets if you look carefully. It's a lot cheaper than Everclear, but you can't consume the excess! Jack K8ZOA On 12/26/2010 11:06 AM, Gary K9GS wrote: [edited to remove non-pertinent parts] > > 2) Once you have most of the goop cleaned off, I recommend using > alcohol to remove any remaining residue. You can use store bought > Isopropyl alcohol but the problem is that the stuff you buy in a store > is only 70%...with the remaining 30% being water. A much better thing > to use is to buy some Ethyl alcohol. Go to your local liquor store and > buy a pint of grain alcohol. Brand name around here is "Everclear". > This is 95% Ethyl alcohol...about as high as you can get outside of a > chemistry lab. Alcohol is naturally hygroscopic (absorbs water) so > you'll never get 100%. > Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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There ya go Jack. I wasn't aware that Walmart sold 90% Isopropyl. I
don't buy it that often. That should work great! On 12/26/2010 10:49 AM, Jack Smith wrote: > I buy 90% isopropyl alcohol at Wal*Mart and use it for PCB cleaning. I > think it's a couple dollars for a quart bottle, available in the drug > section. I've also found 90% at most drug stores or supermarkets if > you look carefully. > > It's a lot cheaper than Everclear, but you can't consume the excess! > > Jack K8ZOA > > On 12/26/2010 11:06 AM, Gary K9GS wrote: > [edited to remove non-pertinent parts] >> >> 2) Once you have most of the goop cleaned off, I recommend using >> alcohol to remove any remaining residue. You can use store bought >> Isopropyl alcohol but the problem is that the stuff you buy in a store >> is only 70%...with the remaining 30% being water. A much better thing >> to use is to buy some Ethyl alcohol. Go to your local liquor store and >> buy a pint of grain alcohol. Brand name around here is "Everclear". >> This is 95% Ethyl alcohol...about as high as you can get outside of a >> chemistry lab. Alcohol is naturally hygroscopic (absorbs water) so >> you'll never get 100%. >> > -- 73, Gary K9GS Check out K9NS on the web: http://www.k9ns.com Greater Milwaukee DX Association: http://www.gmdxa.org Society of Midwest Contesters: http://www.w9smc.com ************************************************ ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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