types of flux core in wire solder

[Clear as mud]

I'm running out of solder, and probably going to order more in the next month or two.  I've been using lead-free solder, MG Chemicals 4901-227G, labeled SN99 and made from 99.3% tin and 0.7% Cu.  The wire size is 0.032 inches, and it's labeled No Clean, but I've been cleaning the flux off the boards anyway because they look better when cleaned.

I would like to try SN100C solder, with a slightly different composition.  I like the .032 diameter so I am going to stick with that.  On the web site I am looking at, I have three choices for the flux core of the solder wire.  The manufacturer is AIM, and the part numbers are 14220, 14168, and 13247.  FastCore 2.5%, GlowCore 2.5%, and WS482 3%.  FastCore and GlowCore are described as no-clean, and FastCore is described as having excellent thermal transfer capabilities.  WS482 is the water-soluble one, halide-free.  Both GlowCore and WS482 are described as "highly active."

I am hand-soldering using a soldering station that has a built-in smoke absorber, but the smoke absorber function quit working because I think it got all clogged up with flux residues.  I may attempt to fix that, but it might stop working again, so the health effects of breathing solder fumes are a consideration for choice of flux.  Another consideration is the fact that I intend to clean the flux off even if it is labeled no clean, so I would like something easy to clean.  I've been using isopropyl alcohol, ethyl alcohol, or acetone for cleaning the flux off the boards.

Any thoughts on which flux I should choose?  I think I once read that the water-soluble ones have bad fumes.

[nanofrog]

Stay away from the water soluble stuff, as it will corrode joints in a matter of hours if not cleaned off. Fine for production, but nasty stuff otherwise IMHO.

If you're happy with no-clean, and you're not soldering some old crusty/nasty looking parts and PCB's, then you won't need the highly active formulation and the Fast Core would be the one to go with. But if you are dealing with highly oxidized stuff, the Glow Core would be the way to go.

Otherwise go with rosin.

[T3sl4co1l]

^ Rosin is more-or-less out because he's talking lead free...

Unless there's a compelling reason (doing RoHS production work?!), I wouldn't touch anything worse than 60/40.

Tim

[nanofrog]

^ Rosin is more-or-less out because he's talking lead free...

Unless there's a compelling reason (doing RoHS production work?!), I wouldn't touch anything worse than 60/40.

Tim

Failed hint to get off the lead-free crap for hobby use it seems.    Perhaps some emoticons would have helped. 

Only reason I see to touch the lead-free alloys is RoHS compliance. Not necessary for prototypes/hobbyist use, so I'll stick with 63/37.

[DanielS]

Only reason I see to touch the lead-free alloys is RoHS compliance. Not necessary for prototypes/hobbyist use, so I'll stick with 63/37.

With all the bad press about heavy metals in the last decade or two, some people have developed an exaggerated fear of them... simply wash your hands and whatever else may have touched them after exposure and everything is fine.

I have a friend who broke a CFL lamp a few days ago and told me he was worried he might get mercury poisoning from that. You would need to eat a couple of whole bulbs for that to happen. Some people are so fearful they call decontamination cleaners.

While I would like to switch to lead-free for my own stuff, most lead-free alloys I can get my hands on are over 50% more expensive and I still have half a spool of Kester 63/37 left.

[Artraze]

I quite like water soluble flux myself.  It fluxes well and cleans up easily.  The tradeoff is that you must clean it, but you actually have a couple days rather than a couple hours.  So unfortunately it can't be your only flux because there will be times when cleaning is impractical or impossible, but I still end up using it more than rosin.

I think that some confusion comes from the fact that there are two type of water soluble fluxes: organic and inorganic.  Organic fluxes, like the WS482 or Kester's 331, are less corrosive and don't generate bad fumes (in my opinion at least).  The inorganic fluxes are basically hydrochloric acid and are extremely corrosive and generate highly acidic fumes, but they are more for plumbing than electronics.

[mazurov]

^ Rosin is more-or-less out because he's talking lead free...

RA, RMA all work just fine with lead free, as well as plain old pine rosin. Liquid flux separate from solder wire will be needed anyway for SMT soldering. MG Chemicals CAT.NO.835-100ML specified for lead and lead free.

I solder lead free for many years and just can't understand why people are so hostile about it (maybe they simply don't know how to solder). Lead-free is nice stuff - you can eat/drink while soldering and you don't need to wash your hands before touching your dick, scratching your eye or picking your nose. You don't need to worry about kids putting circuits in their mouth and you can store you paste in a kitchen fridge next to tomatoes. Also, some very useful alloys, like SnBi, don't have anything close in leaded - and you need to have lead-free tip, or better yet, lead-free bench to use it.