![]() Even "coffee breath" can cause a residue on a multiplier section that is enough to cause a circuit failure in the HV circuit realm. RMA flux and a nice, hot IPA wash works as well, though it should still be baked out. vacuum potting a board that didn't get baked out, but merely air dried is a nightmare as the water left in the FR4 boils out forever! ![]() The trick is that after the aqueous wash, we baked our assemblies at 60C for an hour to completely dry them out, and even vacuumed many at potting time. I made HV supplies on unmasked FR4 medias for years, and we used water soluble fluxes, and aqueous wash. If anything, it encapsulates a solder joint in an oxygen barrier that reduces oxidation/external attack. The hygroscopy of the circuit board itself is higher than the flux left behind. One should make sure their PCB is very clean and well baked out to remove any water the PCB has in it before a no clean soldering operation begins If you don't want to leave the flux on, pick a different flux like RMA. If you have a bad solder or process and end up with stray solder balls, maybe you would have to clean it off, not because of the flux but because the balls exist at all. I don't see how they can make it any easier to understand, when they call it "no-clean", they really, really, really really (really) mean it. The whole point of using one is if you don't want to clean it off. One trick is NOT picking one that cleans off easily, that is a silly idea. While it is possible you used some product years ago that was an exception, in general we'd have to assume the typical modern formulas as what is being referred to. It does not become conductive, absorb water in general. It means the residue is less aesthetically unpleasing for the arbitrary humans that would look at it, and that functionally there isn't usually a need to remove it. It doesn't mean low residue, that is dictated by the % of the flux. The liquid that distills over is 'spirit of turpentine' (the most familiar form of turpentine to us today, traditionally used as a paint solvent) and the glop left in the stillpot, which will harden into a glassy solid, is 'rosin' - which is a kind of resin. Soldering Flux LIQUID ROSIN FLUX 1L (1 QUART) LIQUID 835-1L MG Chemicals 1: 51. No-clean is no misnomer, that's the whole point of using it. Home Products Newest Products Manufacturers Services & Tools. ![]()
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