Cleaning the flux off the PCB

[pingosimon]

What are some tried and true methods? So far I've read about 99% isopropyl alcohol, and my dad suggested TV tuner cleaner

[philetaylor]

Personally I use Electrolube Fluxclene. It come with a useful brush head attachment for scrubbing any difficult to clear flux.

[fussylizard]

I use something similiar (PCB cleaning fluid). I didn't have good luck with plain alcohol (99% might work though but is not as readily available), so I got a dedicated PCB flux cleaner in an aerosol can. I use a little hog-hair brush (from the same section of the same store that I bought the flux cleaner) to help since my can doesn't have a fancy brush attachment like Phil's. :-)

[pingosimon]

Oh nice, I didn't know that existed. Thanks!

[nILS]

OMG it's Flu-In-A-Can! That's just mean!

[tonyn]

Yes 99% isopropyl alcohol does the job, cheaply too.

I found it at a K-Mart pharmacy.

You may have to ask the pharmisist to order it for you though, but it's non prescription.

I like to mix a little Acetone with it to help.

You can get small bottles of 100% Acetone at Walmart, in the women's nail polish section.

Then get a toothbrush and a can of compressed air to blow it off imediately

(available at an office supply for dusting keyboards).

That's for whole circuit boards.

You can use a cotton swab for small areas.

Cheap and effective.

Edited January 11, 2010 by tonyn

[Altitude]

You want to use whatever is made for the flux that you are using but there are decent generic "defluxers"

I have had good success with this stuff at work (https://webvia.techni-tool.com/VIA/viaImagePageIndex.jsp?row=0&pgName=viaListProducts.jsp&searchText=758CH752&modifier=SEARCH&reqTitle=TITLE_VIASEARCHRESULT&newWindow=Y)

The best thing to do however is to use organic flux which is water soluble so you just rinse it off with warm water (much easier to clean) and then use the no clean solder on the no water liking parts.

[tonyn]

You want to use whatever is made for the flux that you are using but there are decent generic "defluxers"

I have had good success with this stuff at work (https://webvia.techni-tool.com/VIA/viaImagePageIndex.jsp?row=0&pgName=viaListProducts.jsp&searchText=758CH752&modifier=SEARCH&reqTitle=TITLE_VIASEARCHRESULT&newWindow=Y)

The best thing to do however is to use organic flux which is water soluble so you just rinse it off with warm water (much easier to clean) and then use the no clean solder on the no water liking parts.

Well I like DIY.

Plus I am an old time solderer that has been doing it before the "green thing".

To me water and electronics don't mix well :)

Any solvent that does it and doesn't detroy anything else, is all you need.

Isopropyl Alcohol, Acentone, Methal Ethal Keytone,

are all solvents used in flux cleaners, and to clean plastics, etc., without destroying them.

Plus those are used in mixtures in a lot of your commercially sold flux cleaners.

So why spend the money when you can be a chemist and make your own!

The purer the Isolpropyl Alcohol, the less chance for left over residue.

99% is about as pure as you can get it, but 91% will work too.

Acetone(nail polish remover, make sure it's 100% pure though, Walmart),

and Isopropyl Alcohol(available at any pharmacy) are cheap and easy to get too.

Removing flux is no big deal.

Basically you want to remove the flux so debre won't stick to the circuit boards later, causing shorts, etc.

It can also remove solder splashes, whiskers, etc., and lets you see if you left any unwanted solder on your boards, better.

Blasting air on them gets the solvent off before it drys, that's all.

You can used compressed air for that, or blast it off any other way.

I have a small compressor that I use for air brush painting, that if I didn't want to spend money on a compressed air bottle,

I could use too.

I just use Alcohol and Acetone.

Using Metal Ethal Keytone instead of Acetone will slow the drying time too, if you want to go that route, and add that instead to your mixture.

Some people leave the flux on?

It depends on the circuit board too, more chance for shorts, the more you want nothing sticky on it, etc.

In factories that can afford it, they completely clean them even with ultrasonic, as I have done when working in a factory.

So whatever works for you and you want to spend the money on ...

Edited January 16, 2010 by tonyn

[Altitude]

..

To me water and electronics don't mix well :)

..

Try it, you will be surprised. I would not even think about think about rosins after using organics (14 projects later). Leaving the flux on is just fine btw, that's why it is called "no clean" flux

Edited January 16, 2010 by Altitude

[svenbogaerts]

Isopropyl => Yes

Acetone =>NO!

Acetone can dissolve some plactic parts, ceramic parts, coatings, etc...

Isopropyl will do the job, but it dries very slow. Use of an antistatic brush to clean and antistatic cleaning tissues to dry and take away residues is always a good idea.

[daleong]

I don't know about any of the modern flux removers, but when I worked for Moog, we used denatured alcohol and a wire brush. You can put me in the camp that says avoid acetone too - it attacks too many plastics! Polystyrene capacitors are particularly vulnerable.

Edited February 12, 2010 by daleong

[MidiSax]

Hi guys.

I've been using methylated spirits and a toothbrush for years. Cheap, easy to get and does the job real well.

[TheAncientOne]

Another vote for the IsoPropanol here. Start off with pure IPA to loosen the flux, (an old toothbrush works well), then wash over with a mix of IPA and water, with an optional drop of washing up liquid. Rinse with pure water and dry with a hair dryer. This is similar to what some commercial PCB cleaning systems use, only they usually have solvent recycling built in.

Acetone can easily dissolve the solder resist coating on some boards, and it can kill some plastic components. Polystyrene caps are especially vulnerable, (and expensive!). I wouldn't ever use it neat on a board myself.

[BuriedCode]

I've used cheap nail varnish remover (from the wife/gf) which is claimed to be 'non-acetone', and lighter fliud :) Both do the job, but require scrubbing with an old tooth brush,or some paper tower. Whatever you use, it'll stink, and possibly get you high if you're not in a well ventilated area. Btw, I use 'no clean' fluxed solder, which is a cop out, since its a bitch to clean.

[sineSurfer]

Isopropyl alcohol + toothbrush + paper towel + cotton swabs here, the first pass it gets all sticky but a couple more passes get everything flux free.

Sometimes, in small pcbs I just scratch away the flux with a wooden toothpick :)

[Antix]

Hi guys,

Just tested on job in these days:

Ethilic alchool whith a nails brush to remove flux

after

distilled water ( or demineralized water ) to remove any stains and streaks leaved by

alchool.

all these operation i made in little tanks but not submerging boards,I soak the brush and brush the board perpendicular to the liquid surface.

I am very positively impressed from the result that is very very professional :thumbsup:

Normally I use commercial flux cleaners ( very expensive ) so I think that it will be my stable method of cleaning, cheap and aesily available materials

best regards

Antix

[rvooh]

i got fluxclene and it works great

word of caution: it kills certain trimpots.. solder trimpots after cleaning!!

[nILS]

solder trimpots after cleaning!!

And how do you clean the flux from the trimpot-soldering? :whistle:

[rvooh]

And how do you clean the flux from the trimpot-soldering? :whistle:

unless you're using very dirty acidic stuff, just the regular way of cleaning will do that (copper brush, ...)