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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.

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  • \$\begingroup\$ IPA is also quite flammable (flash point below room temperature). \$\endgroup\$ – Spehro Pefhany Oct 29 '14 at 15:56
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    \$\begingroup\$ Who makes the flux? You might look at their website and see what they recommend. Why use "no clean" flux if you are going to clean it? (We used it for a while, but I revolted, and banned it.) I think we are now using a water soluble flux and water with a weak alkaline surfactant (detergent) in it. \$\endgroup\$ – George Herold Oct 29 '14 at 15:56
  • \$\begingroup\$ I would very much be interested in a solution for this as well. I'm nervous about water soluble... as I've had a fairly good assembly house apparently fail to clean it entirely (under a TQ144 chip) which resulted in two field failures when it leeched out and reacted with the pins. \$\endgroup\$ – darron Oct 29 '14 at 16:01
  • \$\begingroup\$ Are you doing exclusively panels or exclusively loose boards? For loose boards, aerosolized IPA may be your best choice. \$\endgroup\$ – user36129 Oct 29 '14 at 16:08
  • \$\begingroup\$ i checked the solder wire datasheet and it recommends IPA with water at 60º, or their solution I cannot find in any store \$\endgroup\$ – Javier Loureiro Oct 29 '14 at 16:13
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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

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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.

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