Using Ultrasonic for PCB cleaning - Page 1
Forum section: electronics / beginners

author: sairfan1
author_rank: Frequent Contributor
timestamp: June 19, 2023, 05:46:33 pm
content: I recently bought Ultrasonic cleaner from aliexpress, I want to know.1. Is there any safety related things that I should be taking care of2. what kind of liquid we use to clean PCBs after soldering, is there something that we can make at home?

author: gnuarm
author_rank: Super Contributor
timestamp: June 19, 2023, 07:10:24 pm
content: A small PCB assembly house I worked with used regular dishwashers to clean solder flux off circuit boards. I don't think the ultrasonic cleaner is needed at all, and may do damage to certain parts like crystals.If you are just cleaning one board, I'm told you can just use water and a toothbrush. It's important to select the right soldering flux. That makes a big difference.Oh, the tricky part is cleaning under the parts. They typically have 5 to 10 mil clearance, which is hard to get clean. That's why it helps to use a lot of water like in a dishwasher.

author: JustMeHere
author_rank: Frequent Contributor
timestamp: June 19, 2023, 08:01:12 pm
content: Just use a "static safe" brush and some rubbing alcohol. Make sure to wash the board. Don't just rub it around. Spray flux cleaner works well too. (I use a toothbrush)

author: jpanhalt
author_rank: Super Contributor
timestamp: June 19, 2023, 09:52:54 pm
content: Quote from: sairfan1 on June 19, 2023, 05:46:33 pmAny manual for consumer goods sold in Canada or the US probably has more pages devoted to "safety" than how to use.As for cleaning fluid, I use ZEP (brand) acrylic floor stripper diluted 1:3, i.e., 1 part ZEP to 2 parts distilled/deionized water. Two minutes + 2 minutes rinse in the same water leaves a spotless and almost dry board (solder resist is highly hydrophobic). Watch out for items that are not water proof, like switches. ( I add them later and spot clean with absolute ethanol.) ZEP floor stripper is chemically the same as Kester's water-based flux removers. It even includes a "saponifier" (Kester's buzz word).Of course, if your are afraid of water chemistry, organic cleaners will work too, but their combustible fumes are heavier than air, which is in theory an added risk.

author: MMMarco
author_rank: Regular Contributor
timestamp: June 19, 2023, 10:02:11 pm
content: Normally you use IPA to clean off flux residue, but don't put IPA in your ultrasonic cleaner unless is specifically designed for it.The reason is the high risk of explosion, IPA vapor can easily explode due to a small electric discharge.Don't put anything other than water in your ultrasonic cleaner, unless the manufacturer tells you otherwise.Small Note: Personally, I wouldn't trustanythingbought from aliexpress, but that's just my opinion.Instead of just water, it's recommended to use "Deionized water" (not the same as distilled water) for PCB cleaning.I just use an anti-static brush likethiswith IPA, then spray it down with deionized water.

author: jpanhalt
author_rank: Super Contributor
timestamp: June 19, 2023, 10:10:05 pm
content: Quote from: MMMarco on June 19, 2023, 10:02:11 pmBS

author: MMMarco
author_rank: Regular Contributor
timestamp: June 19, 2023, 10:14:31 pm
content: Quote from: jpanhalt on June 19, 2023, 10:10:05 pmWhat's BS?You know, instead of calling things "BS" you should explain yourself why you think this is BS.Pretty unfriendly attitudeBut do what you wanna do, if you think putting IPA in an ultrasonic cleaner fromALIEXPRESSis a good thingJust ... keep your distance away from meYou know what, I'm not even going to argue with you.Someone who just says "BS"clearlyisn't interested in proper discourse, so you can forget about that.cya

author: thm_w
author_rank: Super Contributor
timestamp: June 19, 2023, 10:50:02 pm
content: Quote from: MMMarco on June 19, 2023, 10:14:31 pmIts a communications confusion, you are saying not to use any base other than water. I'm sure you didn't mean only use pure water in a ultrasonic cleaner, as that would not be effective.The base is water then mixed with 5-20% of detergent or solvents.https://blog.sra-solder.com/knowledge-base/9-easy-steps-to-clean-a-circuit-board-with-an-ultrasonic-cleanerhttps://www.eevblog.com/forum/reviews/pcb-ultrasonic-cleaner-recommentation/https://tovatech.com/blog/609/ultrasonic-cleaner/ultrasonic-pcb-cleaner-for-safe-cleaning

author: MMMarco
author_rank: Regular Contributor
timestamp: June 19, 2023, 10:56:21 pm
content: Quote from: thm_w on June 19, 2023, 10:50:02 pmI said don't put anything other than water in an ultrasonic cleaner because normally you would use IPA to clean PCBs which is not suitable for any ultrasonic cleaner.Thanks for the clarification.I'm just disappointed that people take the time to reply with one word like "BS" then think they can leave it at that.Pretty horrible communication skills. I'm not offended, but I think it's pretty stupid to quote a whole post with ''BS''.Thanks again.

author: jpanhalt
author_rank: Super Contributor
timestamp: June 20, 2023, 12:30:31 am
content: Quote from: MMMarco on June 19, 2023, 10:56:21 pmSorry, but only water in an ultrasonic cleaner to clean PCB's is BS (i.e., ridiculous and without common sense). Who said one would "normally" use IPA? I have never done that in an ultrasonic cleaner or otherwise. It may work, but it is not the best cleaner. I do use organic solvents for cleaning small sections of a PCB with a brush and compressed air.Maybe you, but not everyone else considers that normal. Sure, the flash point is about 12°C (diethyl ether* is -45°C), but that is in a closed system. In open air and mixed with water it is relatively safe. Of course, distilling an open pot of IPAover a bunsen burneris not wise. Some unthinking/ignorant chemistry "professor" at a local college had a serious laboratory fire by doing something similar several years ago. Instead of firing that incompetent, the school decided to get rid of chemistry labs. Nothing is foolproof.*Diethyl ether is considerably more dangerous from a fire/explosion standpoint.

author: Ground_Loop
author_rank: Frequent Contributor
timestamp: June 20, 2023, 12:38:28 am
content: I use either IPA or ethanol heated to 45C. Always works and house not burned down.

author: notsob
author_rank: Frequent Contributor
timestamp: June 20, 2023, 03:05:21 am
content: Have a look at Rossmann Repair Group - Louis has some videos on cleaning.The group also sells BRANSON cleaner concentrate

author: gnuarm
author_rank: Super Contributor
timestamp: June 20, 2023, 03:19:09 am
content: Quote from: MMMarco on June 19, 2023, 10:02:11 pmYou use beer to clean circuit boards? I don't think that will typically produce an explosive atmosphere, unless you are drinking it.

author: helius
author_rank: Super Contributor
timestamp: June 20, 2023, 03:31:25 am
content: The hazard with flammable solvents is that sonicating them sends a large volume of vapor into the air. This effect was used in some room humidifiers that used an ultrasonic transducer to turn water to vapor without heating, producing a cool mist. Because the electronics in a typical ultrasonic cleaner contain relays or mechanical timers, the potential exists for that vapor to be ignited by a spark.Using isopropyl alcohol is therefore not a great idea.

author: Jeroen3
author_rank: Super Contributor
timestamp: June 20, 2023, 05:54:59 am
content: Using ipa without proper fume hood and equipment is not ideal.

author: MMMarco
author_rank: Regular Contributor
timestamp: June 20, 2023, 04:34:44 pm
content: Quote from: gnuarm on June 20, 2023, 03:19:09 amYes, I admit, I use beer, the benefit is you can drink it laterit's like ... two birds with one stone

author: gnuarm
author_rank: Super Contributor
timestamp: June 20, 2023, 05:10:33 pm
content: Quote from: MMMarco on June 20, 2023, 04:34:44 pmI mean, IPA is India Pale Ale, right?Personally, I don't touch the stuff. Too bitter to pair well with the aqueous flux.