exxos's Atari, Amiga & retro forum

I have been meaning to ask this for a while but always forgotten (and been ashamed a little, too :D). There have been a few posts about this but it was never something conclusive. In short -- every time I do some soldering work (recapping is the worst), the PCB looks like a mess. It's sticky, with stains after the soldering pasta, just terrible really. To this day I haven't found out anything better than the ear swabs + IPA. But frankly, I hate it so much:

• it doesn't scale well for big PCBs
• it leaves traces of the wool, especially around through hole soldered components
• it requires several iterations
• it is never perfect!

So I have been wondering, what the professionals use? Or at least people who are actually skilled in this area? ;-) I've seen those (mostly) Chinese ultrasound cleaners, ones which could accommodate Falcon PCB cost >1000 EUR but several people told me that this is not a good idea for PCB with SMD soldered, like the Falcon is. I have been told that ones which would be good for PCBs like Falcon have price tags with one more zero.

So is there a way out?

I wouldn't call myself a professional :) but for large scale cleanups I tend to use IPA in a small spray bottle and an ESD safe plastic brush to remove flux like this.

If I can, I clean up as I go along though, so that I don't end up with a whole board to clean. By doing it a bit at a time the flux doesn't get much of a chance to harden.

Lint free swabs and wipes. IPA. Toothbrush.

IPA and an electric toothbrush.

I developed the following procedure while making the stuff I sell...

1. Bathe in IPA bath
2. Scrub with toothbrush
3. 2-3 mins/side in the ultrasonic cleaner (with cleaning solution & 60C)
4. Rinse under tap
5. Submerge in demineralised water (I use dehumidifier water)
6. Bake at 120C in fan oven for ~30 mins

Works really well on batches of stuff. The IPA bath and pre-scrub can be done while the US is heating up.

cmorley wrote: 20 Feb 2022 11:25

1. Bathe in IPA bath
2. Scrub with toothbrush

I do that too, but it's only usable for small board really.

Similar thread here https://www.exxosforum.co.uk/forum/viewt ... 826#p31484

exxos wrote: 20 Feb 2022 14:19 Similar thread here https://www.exxosforum.co.uk/forum/viewt ... 826#p31484

Yes, this is the one I remembered. So it seems we have a IPA camp, a ultrasonic camp and both camps combined. :D

The idea of soaking it in IPA sounds interesting, it never occurred to me that it could have a better effect when kept overnight. On the other hand, you Chris seems to be more a fan of the cleaners with proper fluids?

I have recently found spraying a large area with contact cleaner seems to have a very good effect of getting a LOT of gunk off fast. So for cleaning an entire motherboard, these days I would probably go into the garden and just give the board a really good spray (you can get specific PCB cleaning sprays but I don't know if they're any better) the WD40 contact cleaner has impressed me. Then take it inside and pour a little IPA on and use a carbon brush on difficult areas.

I once had to clean a board that was covered in electrolytic fluid. It was an apple 840av board infamous for it. In this case I went for a very thorough scrub with boiled distilled water in the sink with ultrasonic fluid. Then I put it in the oven for about an hour at 77c (I think) to dry it out. But yeah that was for some serious electrolytic corrosion.

Oh and the flux mentioned in this thread is excellent! https://www.exxosforum.co.uk/forum/viewt ... =35&t=5060

Great for rework, smells great and super easy to clean! Half the battle is won by using good flux like this in the first place :)
I use MG Chemicals watery no clean flux for most basic jobs. But for rework or high temp work I use that chip quick now.

I use a dishwasher. Nothing beats it.