next topic »

[on:]

what is the best way to remove flux residue after soldering SMD devices
everything is working, just doesn't look very nice with muddy stains all over the boards?

cheers
Mike

[Reply #1 on:]

http://lmgtfy.com/?q=remove+flux+after+soldering

[Reply #2 on:]

[Reply #3 on:]

I use IPA solvent. http://cpc.farnell.com/pro-power/ppc103/ipa-cleaning-solvent/dp/SA01884?in_merch=Featured%20Products

[Reply #4 on:]

I have used acetone and 90% Isopropyl alcohol before with success... however you must be careful with plastics as both of these chemicals react with some plastics. It should be fine on a PC board though.

Hugo

[Reply #5 on:]

what is the best way to remove flux residue after soldering SMD devices
everything is working, just doesn't look very nice with muddy stains all over the boards?

cheers
Mike

I just use water and a tooth brush, works fine with a little patience. I've found too many times that some chemicals like Isopropyl alcohol on some PCBs cause a smeary mess that's hard to clean off.

Lefty

[Reply #6 on:]

I've used denatured alcohol (aka methylated spirits) for over 30 years with good success. It's safe for most plastics, with ABS (changes the color) and Lexan (makes it cloudy) being the exceptions I know of. It's readily available, dries quickly and is relatively cheap. I use it with a small, stiff plastic-bristled brush to scrub the boards after soldering.

Isopropyl alcohol also works well. Make sure you get actual high-concentration (85% or better) Isopropyl (or Isopropanol) and not the commonly available "rubbing alcohol", which contains glycerine and will leave a residue.

DON'T be lazy and just soak the boards in alcohol. Despite being relatively mild solvents, given enough time they will disolve a lot of things.

There are also many commercial electronic spray cleaners that remove flux. Some will severely damage (even dissolve) plastic despite being labeled "safe for most plastics". They never seem to say exactly what plastics are included in "most", so I recommend you test them first.

The older formulations from 20 years ago worked great but were either carcinogenic or ozone-depleting and have been banned. The newer concoctions don't seem to work as well to me so I've gone back to using alcohol and a brush.

BTW, use in a well-ventilated area and away from spark or flame. Alcohol flames are nearly invisible.

I use IPA solvent. http://cpc.farnell.com/pro-power/ppc103/ipa-cleaning-solvent/dp/SA01884?in_merch=Featured%20Products

Isopropyl alcohol in a spray can. Probably cheaper to just buy a bottle.

[Reply #7 on:]

90% alcohol from Walgreens. ... and a toothbrush.

Before the alcohol dries, you need to dry it with a dampcloth. Otherwise, the flux that you brushed and got dissolved in alcohol, will remain on the board after the alcohol evaporates... leaving a film mess.

Sometimes it takes a second scrubbing (and helps if you also brush all the alcohol off the board, so it's taking with it all the dissolved flux)

Remember, before the alcohol evaporates, it needs to be patted down with a cloth. That's the trick for me. 

[Reply #8 on:]

thanks for all the feedback
will give some a try

[Reply #9 on:]

One plastic that is very intolerant of most solvents is polycarbonate - even the oils in citrus
peel will dissolve it!

If you are using solderpaste to solder SMT components then look for "no-clean" solder
paste - the flux evaporates I think, leaving hardly any residue.

For rosin flux a two-stage cleaning process seems to work for me - first spray on and
scrub to break up any hard lumps.  Secondly apply more solvent and allow to drain from the side of the board, this
tends to carry away most of the rosin (which will just precipitate out again if the solvent
dries in place - so do this cold to reduce evaporation (the first application tends to reduce
the board temperature nicely!)

[Reply #10 on:]

If you use a water soluble flux cleaning is easy. 1. Lather, 2. rise, 3. Repeat...
If not and you use a solvent containing water (AKA Alcohol) you must wait until or dry the PCB first, A heat gun works very well.
{Edit RKJ}
AS MarkT pointed out above orange oil is the best solvent for that purpose.

Bob

[Reply #11 on:]

Plus a toothbrush, or if you want to be really cool:

[Reply #12 on:]

Denatured ethanol or tetrachloroethylene, a toothbrush, and an air compressor. Brake cleaner (Brakleen brand in the red can, not the green can) is tetrachloroethylene, and works well. Best used outdoors.

[Reply #13 on:]

Any chlorinated solvent should be used with plenty of ventilation...  Or avoided(!)

[Reply #14 on:]

We like to say, "Better living through Chemistry!"