anyway, the other problem with kester 44 is not it's not very stable compared to most fluxed solders. it has a shelf life of 2-3 years, and needs to be kept within safe humidity and temperature ranges that are smaller than lead free mildly fluxed solders.
Hm. Can you elaborate about this point? I’ve read a bunch of random comments online from people saying they’ve used the same spool of Kester 44 for decades. What happens to expired flux/solder?
in the best case, the flux just becomes less active. the activators in it are usually either halides or fluorides. i can't remember exactly what Kester RA uses, but i don't believe it uses halides or if it does they neutralize on vaporization and aren't left in the residue.
you might recall that the physical interpretation of the word flux is not a name for a substance but a noun which refers to the flow of some other noun. in this case, solder flux facilitates the flow of molten solder over two metals that one wants to be electrically joined. in this case, the thing that prevents this from happening is generally the oxide layer that forms on metals when they are exposed to oxygen (almost all useful metals want dem oxygen electrons). hence, flux, the substance, is a corrosive compound which, when vaporized in contact with metal oxides, dissolves or otherwise makes them go away.
so, in the best case, your 10 year old spool of solder (i had one too!) is just a spool of metal alloy with a low melt temperature and a mostly inert substance running through the core of the drawn wire.
in the worst case, the flux eats through the solder alloy itself and affects the alloy composition and physical structure of the drawn solder wire. i've seen (and thrown away) rolls of solder that looked like they bled to death.
another issue is that of lead. lead really likes oxygen. especially in very thin solder wire, a large amount of lead is exposed to oxygen and can form a very very thick oxide layer. as above, the flux core is supposed to help deal with this, but over the last decade it became a gross inert bit of tree sap, so your solder is not quite the alloy you thought it was and does not have the same conductivity or flow properties it used to. that can be bad, particularly if you're new to soldering. i personally use a roll of kester 44 i got off ebay and expired about 2 years ago. i also keep a large fresh bottle of activated rosin flux around, and thoroughly clean my boards of flux residue.
in short, kester 44 RA 63/37 0.02 is pretty much the best hobbyist and leaded solder WHEN IT'S NOT EXPIRED. after it expires it usually stays workable, but you have to be a bit careful with it.
kimwipes are probably overkill on all but the most intricate of SMT designs. i have a flux remover spray full of pretty much every organic solvent you can think of that i use (i think it's an mg chem product, but it could also be chemtronics). i then scrub the crap out of it with a nylon brush. iso (anhydrous, not that rubbing alcohol crap) also works for most flux residues. then i just let it dry. keep in mind that organic solvents are volatile as crap and vaporize immediately and then smell like crap for hours. i do this in the bathtub and then i leave the bathroom and go work somewhere that doesn't smell like crap.
