![]() fluxes for wavesoldering come in 50 gallon drums. so much that there is residue and you need to remove it. those are formulated for rework and the idea is to use a lot of it. and then there are specially formulated fluxes like the gel fluxes or tacky fluxes. ) it is also more agressive as it has a shorter time to do its work. the flux in solder wire is a different composition than the flux found in pens or liquid form ( for starters the flux in solder wire is dry powder. boards that have been reworked ( manually touching 1 component ) will have residue and those need washing with iehter solvent based flux removers or water. if reflow is done correctly there is little or no flux residue and board wash is not required. when doing reflow you have a rampup to flux activation, a hold phase to ledt the flux do its work and evaporate for almost 75% and then you ramp up to liquid phase where the solder melts and flow on the remaining flux. then it goes through the solder wave where the flux totally evaporates leaving a clean board. wave solder machines apply warm flux to the board first, let it soak for a few seconds as the conveyer moves over a warming plate and the flux is now activated. under a correct process the flux is given some time to activate and do its work before soder is applied. this lets the solder 'wlow' over the to be soldered surface. The second thing it does is lower the surface tension of the solder. So it converts copper oxide back into copper. It is so reactive it can strip oxygen molecules that have already bonded with copper. flux works on two fronts : When activated ( temperature controls this, most fluxes kick in around 100 degree C ) flux is a very reactive element that want to bind with oxygen molecules. the rosin is just a carrying vessel for the real active ingredient. RA = rosin activated ) it is actually not the rosin that is the flux, but another substance in the compound. ![]() RMA is the most prevalent rosin flux ( RMA Rosin Mildly activated. ![]() There are some very agressive fluxes like RA that must be removed as they contain acidic substances. very weird) ipa is perfectly safe for electronics. isopropylalcohol does not attack plastics ( apart from one kind of transparent material that just falls apart like a smashed car window. if there is a lot of residue your process is wring and you need to remove it as it can be conductive - water soluble flux needs to be removed simply because it is hygroscopic and leaves a soap-scum like residue on the board that is conductive. no problem -low solids flux is a flux that under a correctly controlled process totally evaporates. Rosin based flux is generally not conductive unless you baked it at such high temperatures it turned caramel color or black. ![]()
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