How do you clean your PCBs?

I don't remember where I originally saw it, but I usually fold a paper towel several times until it's about the size of a business card and soak that in 99% IPA. Then, I hold the board over a trash can and scrub the board with that paper towel and all the little bits of paper towel that get ripped off end up in the garbage can. It works surprisingly well. If there's any lint or pieces stuck on the trimmed leads, I'll use an ESD-safe brush to get the rest off.
 
Let's swing the question around the other way. Has anyone experienced failure from not cleaning the PCB?
I have, I think I mentioned this in another thread a while back. I switched over to Kester "331" which is an organic water-soluble flux. It leaves a milky white film on the board after soldering and it turns out it's mildly conductive, so I had a bunch of weak shorts all over the board that caused problems. Never had it with "44" flux, which is non-conductive.

Needless to say I wash my boards now. I have a resin 3D printer that has an accompanying washing station for printed parts. I use filtered water with a drop of dish soap and wash the boards (up to 5 at a time) for about 5 minutes in there. Then I take them out to the drying oven set for 65°C and let them dry for about 15 minutes, they come out looking fabulous.

I washed a couple "44" soldered boards in the washing station filled with isopropyl instead of water and the solder joints come out clean, but it leaves an ugly residue on the board. So now I use 331 solder for most things and wash the boards, then I keep a spool of 44 on hand in case I need to do any soldering and don't want to have to wash.
 
As long as there's no power (and everything is dry before you apply power) you'll be fine.

The folks who like to burn speed holes in to their caps might have a hard time with it, though.
Ok, I'll give the alcohol bath method a shot. But if I "bust a cap" I know who to blame. ;P (totally kidding of course)
 
As long as there's no power (and everything is dry before you apply power) you'll be fine.

The folks who like to burn speed holes in to their caps might have a hard time with it, though.
I thought 99% IPA could melt poly caps. Also you *never* want ipa to get into pots or switches
 
IPA in pots and switches is ok if it's clean IPA. I flood my boards with 90% IPA before installing the pots or switches. Scrub with a toothbrush. Repeat until clean. I think the best argument for cleaning the boards is it facilitates inspection. In very high impedance circuits (>>1MΩ), even the tiniest current leak can upset the bias. Flux residue will absorb moisture from the air and become conductive.

I've seen plenty of filthy boards that work fine, but why tempt fate?
 
IPA in pots and switches is ok if it's clean IPA.
Good to know! I had always heard that ipa reacted with the binding agent used in the carbon track of pots, and that IPA getting into a pot would essentially melt it. Same deal with switches— I had heard that IPA caused crazing on the switches, and that over time the switch would degrade and mechanically fail.

My board cleaning practices are pretty efficient as it is, but now that I know that pots and switches will be fine if a tiny spare bit of clean ipa gets on them, I’ll have less time spent super-carefully navigating around them on the final tough ups.
 
For me, the best defense for cleaning a PCB starts with the flux used. I found no-clean flux like this to work really well:

Chip Quik CQ4300-2OZ No-Clean... https://www.amazon.com/dp/B093X9F9RN?ref=ppx_pop_mob_ap_share

I typically use some good plastic bristle brushes and good iso to clean them and use Kim towels to dry them.

I like the idea of an alcohol dip bath. But is that bad for any particular components?
So far the only thing I avoid (and have had problems with) soaking (swishing actually) in an IPA bath is potentiometers. Particularly trimpots. I think the dissolved flux gets into the wiper wafers and can mess them up. So when I do a board that has trimmers, I'll populate everything except the trimmers, then after cleaning I'll solder in the trimpots.

When I was building my first Space Heater attempt it was the first time using an open coil inductor so I wasn't too sure about that and skipped cleaning, to my detriment I think. My second Space Heater build I just populated everything but the tube and soaked it.
 
Still haven’t found a good IPA. I don’t understand the American obsession there..
Dogfish Head 90 Minute IPA is one of my goto favorites, although here in the US there are tons of small craft breweries that make some excellent IPA's. *Note that the 90 Minute is very different from the 60 Minute, one would think it would just be the alcohol content difference but the 60 Minute is kinda "meh" while the 90 Minute is fabulous, nice and malty and hoppy.

For "everyday" IPA I like the Sweetwater 421 (not a true IPA) as well as their IPA.

But, I needed to lose some weight a couple of years ago and dropped some significant poundage (about 40lbs). And alcohol was one of the first things I cut out. (That and most carbs)
 
Honestly I'm shocked y'all are submerging your pcbs
SWISHING! not submerging....hahaha.....actually, I was somewhat leary of this at first too until reading @Chuck D. Bones's post.
But I'm a convert.

I use a little shallow plastic food container, pour in about 1/4" of alcohol, drop the board in there and swish it around to loosen up the flux. Then use a plastic bristle brush, scrub, the swish some more then as of late, I'll shake the board off and use some compressed air on it.
 
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