Cleaning PCB using a dishwasher? Let's dig into it. - Page 1
Forum section: electronics / general

author: Zucca
author_rank: Unknown
timestamp: October 10, 2024, 01:12:26 pm
content: I found scattered info around www and in this forum, let's put here all our experiences/tips/suggestions/complains/discussions with cleaning PCB with using a dishwasher.I heard that piezos and dip switches suffers with water immersion cleaning...PS: If you think this is madness, rumors says Tektronix was cleaning customer PCBs in a dishwasher prior to repair them...

author: Zucca
author_rank: Unknown
timestamp: October 10, 2024, 06:25:48 pm
content: https://forums.arcade-museum.com/threads/pcbs-dishwasher-safe-or-not.219336/https://www.eevblog.com/forum/projects/washing-pcbs-in-dishwasher/

author: floobydust
author_rank: Super Contributor
timestamp: October 10, 2024, 07:07:19 pm
content: One company I worked for used commercial dishwashers for washing their PCB's. They leased them from a restaurant equipment company. When one machine died another would be brought to replace it- but we did wonder about solder deposits inside in the food industry.It was a special detergent PCB Wash then an air dry on a rack for a few days. I can't remember if an oven was used because the moisture stays trapped inside them so it's not great. I can't remember if a rinse agent was used, the boards were very sensitive for leakage currents.Compressed air blow off not recommended due to the static electricity generated.Most wash-sensitive parts have tape seals.Tactile switches must be "washable". Omron gives 1 minute max in a bath and total 3 minutes cleaning time.Using a dishwasher for newly stuffed PCB's worked fine for the company, for many years.

author: SteveThackery
author_rank: Super Contributor
timestamp: October 10, 2024, 07:28:33 pm
content: So is it really true that a DIP switch is waterproof?What about MEMS microphones? They have a hole in the front - could water get in? We've also got air particle sensors, humidity sensors, miniature speakers (phones and tablets), fans. I'd be reluctant to wash any of those in a dishwasher, but only too happy to do so if it really is safe.

author: thm_w
author_rank: Super Contributor
timestamp: October 10, 2024, 07:56:43 pm
content: Quote from: SteveThackery on October 10, 2024, 07:28:33 pmAs explained above, these items have tape seals that you remove after the wash is complete.Speakers and fans are generally external devices so no you don't wash those when you are washing the PCB..

author: tom66
author_rank: Super Contributor
timestamp: October 10, 2024, 07:57:54 pm
content: As long as the PCB doesn't use glue or aluminium components it should be OK. Dishwasher tablets/soap tends to corrode aluminium.There's also going to be a difference between European dishwashers and American ones. Most European dishwashers heat the water at the end of the cycle, using evaporative drying to dry the dishes. American dishwashers tend to use a heating element. This means European dishwashers will get a lot hotter at the end of a cycle which can damage plastic components on a board.

author: SteveThackery
author_rank: Super Contributor
timestamp: October 10, 2024, 08:01:46 pm
content: Quote from: thm_w on October 10, 2024, 07:56:43 pmOh, you mean they have tape sealsappliedto them. I thought it meant they have tape seals built in as part of the construction.

author: tom66
author_rank: Super Contributor
timestamp: October 10, 2024, 08:05:04 pm
content: Another thing is, if you do use a dishwasher for cleaning PCBs, it should probably be a different dishwasher to what you use to clean things you eat off.I made the mistake of cleaning a pot with emulsion paint in it at the bottom. Only a thin layer but it was enough to contaminate every part of the machine. I was picking paint flakes off plates for weeks afterwards. Hopefully it wasn't toxic.I imagine that could happen too with fluxes, solder residue, glues, etc. None of which are healthy to eat.

author: thm_w
author_rank: Super Contributor
timestamp: October 10, 2024, 09:07:22 pm
content: Quote from: SteveThackery on October 10, 2024, 08:01:46 pmYes built in:Though MEMS I haven't used, so I'm not sure what the usual process is?https://www.eevblog.com/forum/projects/washing-the-flux-off-a-board-with-mems-microphone-or-sensor/

author: SiliconWizard
author_rank: Super Contributor
timestamp: October 10, 2024, 09:13:11 pm
content: Read the datasheets of all your parts to figure out if they can be washed, and if so, how.

author: Psi
author_rank: Super Contributor
timestamp: October 10, 2024, 09:37:51 pm
content: Using a dishwasher sounds fine as long as the temp and water spray aggressiveness is at an acceptable level. And obviously you need a PCB with parts that 'can' be washed. However using dishwashing powder or pods would be a big mistake imho. You'd want to use chemicals designed for PCB cleaning.I can hear someone saying "how can dishwasher temps be an issue". My last dishwasher would melt plastic chopping boards if they were placed in the bottom tray and positioned in the right spot to be just above the heating coil (loop of heating element around the bottom). PCBs are designed to get hot, but there is a difference between 240C for 30sec and 30min at over 100C.Newer dishwashers tend to have the heating element less accessible and don't have this issue, but not all. You can obviously solve this by having your own mounting system to keep the PCBs away from any direct heat source, etc. But I would still do some tests with a thermal probe to check how hot it gets at the spot where you want to put PCBs.

author: SteveThackery
author_rank: Super Contributor
timestamp: October 10, 2024, 09:38:46 pm
content: Quote from: thm_w on October 10, 2024, 09:07:22 pmAh, I see! So they come from manufacture taped. After assembly you can then wash the brand new board. Finally, after drying, you remove the tape to make the component (eg DIP switch) usable. Got it.The bit that confused me was the mention of Tektronix washing boardsbefore repair,implying either that no protection is required, even on untaped DIP switches, or that all the vulnerable components would need manual taping up before washing.Anyway, thanks for clarifying.