Best way to clean solder flux?

What is everyone else doing to clean solder flux? Anyone just use 99% Isopropyl alcohol?

I use the organic stuff and just rinse it off with water

Cramolin Flux-off spray, acetone, or just water in case of glycerol.

I have never cleaned the circuit boards after soldering…should I really? Usually everything works…

Depends on the flux. Some is water based or “no clean”, some of the other stuff is mildly acidic or alkali. The flux is there to help flow and also remove oxidisation or grease from the metal parts.

The stronger stuff needs cleaning off, but I doubt you would get that stuff in cored solder. Maybe if you used a flux pen it would need a clean after.

I use a sharp tip carefully and chisel it off, and then use water an an old toothbrush. But the real trick is clean the tip of your solder iron frequently and/or buy new tips. Then learn to use less flux. You’ll get better at it with practise. For fun take a shot of your present state with a digital camera anmd tehn in say six months do teh same and compare.

By chisel I mean gently from the side. Way too easy to scratch your pcb or damage it so be gentle about it if you do that. Mostly i find solvents make even more mess and or amke the covering on teh pcb gummy and worse etc. So I stopped using it.
Never breathe solder fumes either, right? Value your lungs you only have two.

As an experiment I cleaned some off using some black conductive foam the other day, worked well but gets snagged on solder joints.

The only stuff i know you HAVE to clean off is the organic stuff since it is corrosive. But that only involves rinsing the board in warm water so it is not really a big deal. Beyond that, its just a question of aesthetics. Also DONT use acetone, it will melt a variety of plastics

altitude - what organic stuff? will i have this on a board just using regular leaded solder?

I’ve only bothered to clean where the flux or some impurity has smoked leaving white marks on the board.

I have no-clean lead-free kester 275 95/4/1 solder and don’t clean at all. The solder was expensive but I think it’s worth not having to clean and not having to think about lead issues (especially because I have a toddler). I previously used kester 44 60/40 and I cleaned with a flux cleaner I bought at the local electronics shop. It worked better than alcohol but not by a lot. 99% alcohol will work fine if you must clean. Kester 44 says you don’t need to clean it which is good because I did several projects before I was even aware that cleaning was a possibility. I really don’t think it’s worth the time and mess.

The problem is you really shouldn’t get cleaner on certain parts, especially pots (it washes the lubricants away). So you’re supposed to solder all the cleanable parts, clean, then solder the rest? What about the flux you just put back on the board? Carefully clean it with a Q-tip? I have better things to do, like write music or build another project, than sit around and meticulously clean flux off one joint at a time. No-clean is the way to go.

As a warning, the no-clean will not flow quite as well as rosin core. It works just fine for PCB work but for soldering audio wires together it can be frustrating. You can either go back to rosin core for that or buy a separate tub of flux to use when doing big stuff.

Also, the lead-free solder takes more heat to melt so again, it’s not as easy to work with. I think it’s worth the trade off to know I’m not creating more lead-laden junk to end up in the drinking water or causing brain-damage to my kid. Save the planet man! :wink:

Oh, last thing: the organic flux is extremely corrosive. You MUST clean it or it will eat away what it gets on. I would not use it on my projects for fear of not cleaning it well enough FWIW.

If you search “organic” on that page and look under “Rosin Fluxes” you’ll see all the references to it being highly corrosive. Don’t know why your one says it’s no-clean. Maybe it’s such a small amount? What do you need that for anyway? Doesn’t your solder have flux in it? Are you doing lots of SMT stuff?

If it helps and says it’s no-clean then I don’t see a reason to stop using it. I never use a flux separate from what’s already in my solder except for when I’m working on big stuff like audio connectors. Although maybe I’d change my mind if I were working with more bare-copper boards and less pretty pre-tinned boards like the Shruthi :slight_smile:

hmm. what about this stuff that i got off ebay? it’s organic, but “no clean”. me confused.

"Flux Pen Low Solid, Non Clean Flux

The Flux Pen is a halogen-free, non-rosin organic Flux Pen that is specifically designed for rework of conventional and surface mount circuit board assemblies. The extremely low solids content (2.0%) and nature of the activator system results in practically NO RESIDUE left on the assembly after soldering. There are no residues to interfere with electrical testing. Email me if you need the MSDS datasheet."

Well I got it for my midipal failure :slight_smile: so I only needed it for that really…