Author Topic: Removing Flux  (Read 382 times)

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Offline dcbrown73

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Removing Flux
« on: July 01, 2019, 01:13:31 pm »

I've recently been buying cheap kits to practice on my soldering skills.   While many I only used to practice, some I want to keep. (like substitution boxes) and so I went about trying to remove the flux left from soldering.   
What is the preferred method as I read different things from different people.   I purchased MG Chemicals 413B in a spray can and while it removed the bulk of the left over flux, there is still a thin sticky film left.

I also have some 99% Isopropyl alcohol that I use for cleaning other things, but those I usually submerge in the alcohol.  That seems to do a better job than spraying the MB 413 and using a static free brush.   Maybe if the MG 413 wasn't a spray can and I could submerge it in that.

Should I just switch to the alcohol or am I just using the MG 413 incorrectly?  I suppose the alcohol is less dangerous of a chemical.

Thanks for any feedback.
Why exactly do people feel I should have read their post before I responded?  As if that was necessary for me to get my point across.

Online Shock

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Re: Removing Flux
« Reply #1 on: July 01, 2019, 01:42:41 pm »
You are probably just seeing flux residue. It becomes dissolved in the solvent and once the solvent evaporates it remains distributed everywhere the solvent was.

So keep your scrub stage to loosen up and dissolve the flux and add a couple of rinse stages in cleaning or spray it down so the flux can run off with the solvent. If you have problems you can contact the solder/flux manufacturer and see what they recommend or change brands. Remember to use ventilation and fume extraction especially with flux cleaners and non rosin fluxes that have god knows what in them.

As I mentioned in another thread recently, start with as pure IPA as you can get and then cut it down with deionized water, if you need something more aggressive you can make up an IPA or deionized water cleaning solution with an electronics safe detergent or more aggressive solvent. Finally rinse in deionized water or IPA. This is essentially what is done in production.
« Last Edit: July 01, 2019, 01:46:39 pm by Shock »
Soldering/Rework: Pace ADS200, Pace MBT350
Multimeters: Fluke 87V, 117, 27/FM     >>> Fluke 51/52 Thermometer Parts Required <<<
Oscilloscopes: Rigol DS1054Z, Phillips PM3065

Offline radiolistener

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Re: Removing Flux
« Reply #2 on: July 01, 2019, 01:48:45 pm »
I think ethanol (also known as alcohol) is the best way.
I'm using 96% ethanol (C2H6O) and it works great.

Rinse your board in the ethanol for some seconds and then use cotton wool and toothbrush moisturized in ethanol to remove flux. Then rinse it in the ethanol again and clean it with cotton wool moisturized in ethanol.
Then put it on the air for a minute to dry out and that's it :)

The good thing is that ethanol is not toxic, so there is no need to use safety glasses, gloves and gas mask  :D
« Last Edit: July 01, 2019, 02:01:42 pm by radiolistener »

Offline SteveyG

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Re: Removing Flux
« Reply #3 on: July 01, 2019, 01:51:51 pm »
Chemtronics Fluxclene makes short work of it, requiring very little scrubbing

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