For removing rosin flux from my board, should I use Acetone or Isopropyl Alcohol? I need an easily available solvent.
Acetone being used to clean circuit boards can be problematic. The biggest issue that I found was that it leaves a residue in the board that still requires several other cleaning steps to get rid of including IPA and hot water.
Even IPA can leave a residue as it dries.
There is also the problem mentioned in the comments that the acetone can dissolve certain plastics to the great detriment of your electronics assembly. I've seen it eat away the plastic winding wraps on small transformers as an example.
I can't give you a definitive answer, but see below for a small compilation of DIY flux removers that people have proposed. Additionally, you should consider rinsing the circuit in deionised water and air-drying it. (As a final step, a urethane-based conformal coating ≥2.0 mil thick may be advisable to mitigate against tin whiskers and other contaminants.)
N.B. Observe the safety warnings on the packaging or MSDS of any artificial solvent that you use. Also consider making at least two copies of your circuit: one on which to test your candidate solvent(s) for compatibility, and one for the finished product.
Reportedly decent at removing some fluxes, probably including rosin-based ones, but may damage plastics.
1. Isopropyl alcohol (IPA)
2. Mixture of IPA and acetone
Jeri Ellsworth uses, as a flux remover for rosin flux, a DIY mixture of IPA and acetone "in no exact proportions". At least one other person reports success with this recipe, using a 50/50 mixture (by volume, I guess).
3. Methylated spirits
Burton Lang suggests methylated spirits as a readily available flux cleaner.
4. Mixture of methylated spirits, IPA and ethyl acetate
The Get GUI website suggests a different DIY mixture that they claim is suitable for rosin fluxes and also suitable for non-rosin and no-clean fluxes:
- 85% by volume ≥95% pure denatured ethanol (ethyl alcohol), aka methylated spirits.
- 10% by volume ≥95% pure isopropyl alcohol, AKA isopropanol, 2-propanol, IPA.
- 5% by volume ethyl acetate, AKA ethyl ethanoate, EtOAc, EA.
These are apparently the same three chemicals used in a commercial flux cleaner made by MG Chemicals.
Burton Lang (mentioned above) also suggests, as a flux cleaner, the Poly-Clens product, though this may not be available globally, and can damage some plastics. There is a discussion of the Poly-Clens suggestion at Hackaday.
You can use certain dish detergents provided that A: they are not overly acidic/corrosive (rosin/flux itself is fairly acidic) and B: they don't leave any residue/salts. I have had good luck with "hand-safe" detergents. Some people "might" object to it, but I have had far better success with detergents over alcohol or anything else. In truth, there is really no reason to not use a detergent, it's really just a gel consisting of hydrocarbon chains with hydrophillic and hydrophobic components, historically manufactured from some kind of fat and lye. As long as it leaves no residue, or as long as you rinse it off well with distilled water, and you allow it to dry/bake at a low temperature (or blast it with compressed air), you shouldn't have any issues with it, I never have had any issues myself. A lot of the solvents used for flux certainly are not safe to handle, alcohol and detergent are really the only things that won't give you cancer or liquefy your brain. Its simple, cheap, and effective. It's also environmentally safe to use alcohol and dish detergents.
I usually scrub my PCBs with a cotton swab doused in alcohol to get rid of the large blobs of flux, unfortunately even 90-99% IPA seems to always leave a sticky, foul residue, (especially with "no-clean" fluxes) even with mechanical brushing. Dish detergent and hot distilled water, on the other hand, almost always get all of the residue off, especially if you leave it to soak for five or ten minutes. I have heard that manufacturers use a similar process that uses detergents, mechanical scrubbers, and water jets to remove flux, then they either bake them in a low temperature oven (say 60C) or they spray it with compressed air to evaporate all of the water off of the board. Alternately, you can use a water soluble flux and just wash it off with distilled water which is far easier than using traditional or no-clean fluxes. The only reason to use no-clean flux is if you are worried about some residue still remaining after the cleaning process, such as under SMD packages.
If you do rinse your board off with water, regardless of how you clean them, don't use tap water. Distilled water won't have anything in it but water, so you don't have to worry about any minerals, metals, etc that may be in tap water. Distilled water won't leave any residue, and as long as you wash your detergent off, your boards will be residue free.
Acid based would be Acetone.
ISO is more than enough for what I'd assume 99.99% of Engineering@Home Apps. to need. However that being said, they both work wonders on hardened, nasty, PCB, with flux everywhere. So if you want to rejuvenate your board, get acetone, less aqueous the better. Flammable, be careful like you would with a grenade. Use a gritted cloth and rubber gloves to slowly wipe away and immediately let dry your PCB. Circuitry should be ready for Re-Flux within 3-4 hrs if done properly. (Full-ATX Motherboard sized, etc.)