| Electronics > Repair |
| I*really* want to remove Kester 44 flux - what do I need to buy? |
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| BrokenYugo:
--- Quote from: Calambres on July 18, 2024, 06:02:05 pm ---Mr. Carlson swears by "Lacquer Thinner" for flux removal. The problem I find is that what it is known for that in North America is apparently not the same here in Europe, that is, I do not know *exactly*what that "lacquer thinner" is: turpentine?, white spirit? anything else? --- End quote --- Impossible to say beyond "solvent or blend thereof you can still sell suitable for thinning lacquer" without seeing the can and looking up the SDS. Same problem with people who say "brake cleaner" works well, which one? I've seen more or less straight acetone, hydrocarbon blends, acetone-hydrocarbon blends, and that's just the non chlorinated options in broad strokes. You have to be very picky using solvent products off label like this. |
| tooki:
--- Quote from: johansen on July 19, 2024, 04:47:34 am --- --- Quote from: tooki on July 18, 2024, 11:04:36 pm --- --- Quote from: macboy on July 18, 2024, 01:17:41 pm --- --- Quote from: tooki on July 18, 2024, 07:20:06 am ---For what it’s worth, despite the fact that tons of people do so, Kester itself says that “IPA will not clean the residues off the surface of the circuit board after the soldering process.” This suggests that invisible ionic contaminants or activators remain (which otherwise would have remained entombed in rosin). Probably no big deal for most circuits, but still, I think it’s wiser to use flux remover. --- End quote --- Most or all solvent based flux removers will do no better. Salts don't dissolve into alcohols or petrochemical solvents. Kester specifically recommends a saponifier, a water based cleaner that will literally convert the organic rosin into soap, and will wash away the halide salts. The ZEP floor finish stripper recommended above is supposedly such a product and is available to consumers. When using the paper towel method I described above, I don't get any visible residue left behind (especially not that white gunk commonly encountered) and for most purposes of mine, that's good enough. I absolutely agree that for sensitive precision circuits, a better cleaning is needed. --- End quote --- In my experience, mixed-solvent based flux cleaners do a far better job than straight IPA or ethanol. The fact that straight IPA in an ultrasonic bath produces far better results than when hand cleaning suggests that the salts are somewhat soluble in IPA, and that redeposition (or just adhesion) are the real issue. --- End quote --- Its just dilution, the ultrasonic works because you have to fill it with a liter or 3 of liquid. Company i work for has two ultrasonic cleaners, one for prewash and you change the ipa when it turns pink from loctite, and the final wash which gets dumped into the pre wash on a regular basis. Evaporation makes most of thr ipa disappear. Final wash gets changed when you start to notice a sheen on the boards. --- End quote --- Nope, it’s not just dilution. Aside from the fact that filling a normal ultrasonic cleaner with flammable solvent is a bad idea for multiple reasons, including the hazard and the amount of solvent needed (not a problem if used constantly.) Which is why I don’t do that. I fill the bath with DI water, then put the board in a small container or baggie containing a minimum of IPA. I’ve actually used the baggie-with-a-small-amount-of-IPA to remove white residue that earlier hand cleaning failed to remove. Also, the white residue issue is well documented, and it is known to NOT be an issue of dilution, or use of too little solvent. |
| nctnico:
--- Quote from: johansen on July 17, 2024, 04:22:11 am --- --- Quote from: nctnico on July 16, 2024, 10:32:18 pm ---I've found ethanol works better as flux remover compared to alcohol for cleaning up small bits of rework. But using real flux remover works even better but that stuff is in my shed for cleaning entire boards. --- End quote --- without knowing what "real flux remover" you are talking about, --- End quote --- |O :palm: Geez, some people really need their hands to be held all the time. It is simple: you go online to your favorite electronics dealer and order a bottle / can which says 'flux remover' after reading what kind of flux types the flux remover can remove. |
| johansen:
--- Quote from: nctnico on July 19, 2024, 06:58:10 pm --- --- Quote from: johansen on July 17, 2024, 04:22:11 am --- --- Quote from: nctnico on July 16, 2024, 10:32:18 pm ---I've found ethanol works better as flux remover compared to alcohol for cleaning up small bits of rework. But using real flux remover works even better but that stuff is in my shed for cleaning entire boards. --- End quote --- without knowing what "real flux remover" you are talking about, --- End quote --- |O :palm: Geez, some people really need their hands to be held all the time. It is simple: you go online to your favorite electronics dealer and order a bottle / can which says 'flux remover' after reading what kind of flux types the flux remover can remove. --- End quote --- I prefer trichloroethylene. |
| helius:
MG Chemicals Safety Wash II: https://www.digikey.com/en/products/detail/mg-chemicals/4050A-450G/14563348 The SDS lists isohexanes, ethyl alcohol, isopropyl alcohol, and ethyl acetate. It is "effective at cleaning ionic flux residues". There are other comparable products from Microcare, Chemtronics, Techspray, etc. The "safety" aspect is that none of the ingredients are harmful, unlike those containing chlorinated solvents. The odor is mild, slightly fruit-like due to the ethyl acetate. This is probably all you need unless your flux is baked on with hot air, in which case a stronger acetone mixture might be required: Heavy Duty Flux Remover: https://www.digikey.com/en/products/detail/mg-chemicals/413B-425G/9657986 You need to be careful when using acetone as it can melt many plastics. But it is superior at removing black crusty flux residues, cigarette smoke, and soot from burned components. The smell of this product is much stronger, not nasty necessarily, but somewhat unpleasant. It is still very safe toxologically. |
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