How to clean "no clean" flux with a 3L ultrasonic cleaner

Question

I am doing some small batches of PCBs, like 100 each time, using solder wire with no clean flux core.

I am using this solder wire. The datasheet recommends IPA and water at 60º.

Usually, I clean it with 99% IPA alcohol. I mean only that (no water,) I fill my small ultrasonic cleaner with alcohol, clean 90 seconds, then I use a toothbrush to clean a little, then again another 90 seconds

But now, I got a 3L ultrasonic cleaner. I like it because I can heat whatever is inside, but I dont know how to proceed.

I don't think that using 3L of 99% IPA will be a good idea. It is a waste of money (it is like 10 USD per liter for me), and it is very very volatile. So, I don't think I can keep it for a while in a room.

What do you suggest? Can I mix with some water? AFAIK, IPA will lose cleaning power with water fast.

If I use some distilled water, how much do you think I can use?

Do you think I can use some kind of detergent or something?

I know that there are products for this, but I checked in many places and, are forbidden to ship to Spain, or they are very expensive.

Answer 1

From the data sheet of this solder:

Cleaning: Glow Core can be cleaned with saponified tap water or an alcohol and water blend. AIMTERGE 520 is recommended. A water temperature of 60ºC (140°F) is recommended, and should be adequate for removing any post process residues.

Rubbing alcohol and water is cheap. I would go with the OEM's recommendations. If you have problems or issues, it would be cheaper to switch solder than buy an expensive cleaner.

I am not fond of water wash solder, but that gets off into opinion territory. My .02 YMMV

Answer 2

We do all of our production soldering with Kester Water-Soluble flux. AZ2331 is the flux that is in the wave-solder machine and we use wire solder with Kester 331 flux.

The great advantage of this is that hot water is all that is needed to achieve a completely-clean board. We have seen recommendations to add a saponifier to the water when cleaning but this did not result in measurable improvements to surface resistivity in our testing.

We do use some no-clean wire solder but I'm not real happy about the residue that remains. We found that if you wash the board very soon after soldering using a toothbrush with hot water and detergent dish soap, the flux comes off fairly easily.

We do have a decent-sized heated ultrasonic cleaner and I should see how that works for cleaning no-clean flux from a freshly-soldered board. That would be with hot water and dish soap detergent.