Removing flux left by solder wick

I've just desoldered 30 caps from a board and as you can see the wick (Goot brand) has left me with quite a mess to clean up.

Tried IPA + toothbrush which didn't help at all in removal, but did for some reason change the flux into a gunky, chewing-gum like substance (see middle of photo). Would it be worth trying something such as Servisol PCB Cleaner? I'd really like to get the area nice and clean before soldering the new capacitors, any suggestions would be greatly appreciated.

Thanks in advance.

**broken link removed**

I've used alcohol and a toothbrush with reasonably good success. Does IPA stand for Isopropyl Alcohol? If so, perhaps this flux is a non-polar molecule, in that case try a volatile organic solvent, such as hexane, petrol ether, methyl acetate, acetone, etc. Be careful, some of these solvents could dissolve portions of the board itself.

Did the alcohol evaporate off too quickly? I use surgical spirit (I'm not too sure if surgical spirit is the same as IPA) or a flux remover pen, if you just have board to clean then a cleaner pen might be useful to you (might be a bit expensive - £10~£14 in the UK). You could try the IPA on a cloth instead of a brush.

I find the spray flux cleaners or "fast dry" solvent cleaners tend to evaporate too quickly leaving something that resembles what you have (I don't use this out of choice).

I use stuff called ULS (Ultrasolve) from Electrolube. I've yet to see a flux it can't remove. Many years ago I saw it damage plastic coated capacitors but that was probably in the pre-epoxy coating days and it shouldn't be a problem now.
It's also very useful for general de-greasing and for removing photo-resist paint on home made PCBs.

Brian.

I use thinner (a petrolium product) with painting brush (with hard brussles) to clean flux in solder surface.. its good & working for me.. & also there is flux cleaning spray's are available..

bigdogguru: Yes, IPA=Isopropyl.

I was thinking of trying the acetone, but I'm worried about it damaging the board.. Do you (or anyone else) have any experience using it for this purpose?

Rob B: The alcohol did not evaporate too quickly, it stayed on the board for a few minutes. I have tried it with a cloth as well as the brush.

I've never heard of these pens until you mentioned them, they look quite handy.

betwixt: That Ultrasolve sounds like great stuff, I've managed to find a source for it in NSW so I may well give it a shot.

Senthilkumar_rjpm: Thinners seems like quite a harsh chemical to use.. I really cannot risk doing any damage to this board.

Cheers

Petrol or IPA works fine for dissolving flux residues.
Cheers

Acetone is safe on epoxy resins and is a major component in many commercial flux removers along with isopropyl alcohol.

Consider using different (better) braid next time. You can strip the bad flux out of your remaining braid with solvent and reflux it with good liquid flux in the mean time.

KJ6EAD said:

Consider using different (better) braid next time. You can strip the bad flux out of your remaining braid with solvent and reflux it with good liquid flux in the mean time.

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I certainly will. I would have thought the Goot brand wick would be quite "goot" since it's made in Japan, but obviously not..

Any particular brand you'd recommend?

Hewitson said:

bigdogguru: Yes, IPA=Isopropyl.

I was thinking of trying the acetone, but I'm worried about it damaging the board.. Do you (or anyone else) have any experience using it for this purpose?

Click to expand...

Ok, well it sounds like there is a component of the flux which is insoluble in polar solvents, like water or alcohol. So you will have to resort to using a organic solvent, like hexane, petrol ether, methyl acetate or acetone.

KJ6EAD said:

Acetone is safe on epoxy resins and is a major component in many commercial flux removers along with isopropyl alcohol.

Consider using different (better) braid next time. You can strip the bad flux out of your remaining braid with solvent and reflux it with good liquid flux in the mean time.

Click to expand...

The volatility and solvency increase from left to right in the list of organic solvents I provided. You may want to try hexane or petrol ether and if they don't do the job move on to acetone. I have used acetone sparingly, KJ6EAD mentions it is used in the manufacturing process and shouldn't damage the epoxy resins of the board. However, I have had it remove protective coatings and stenciling very quickly, so you may want to test the acetone out a small unpopulated area of board, before applying it wholesale. Also if there is stenciling on the other side of the board, the acetone could pass through the holes and removing it, so you may want to apply it with a cloth. If you want to give acetone a try, just pick up some women's nail polish remover, it is almost entirely acetone with a little coloring and scents added. Many hardware stores carry hexane and petrol ether. All the name brand solvents mentioned by various people are either polar or organic solvents, possibly a mixture of both.

Hope the info helps with your situation.

My guess is that the IPA contained too much water. Was it the 70% drug store IPA or >90% IPA? I use absolute ethyl alcohol ( "surgical spirits" ?) and add about 25% vol/vol acetone (my alcohol happens to be histology grade from a pathology laboratory). The acetone increases the solvent potency, but is probably not really necessary. Look up what rosin flux really is chemically (Abietic acid - Wikipedia, the free encyclopedia). It is a terpene, hence the improvement with a little acetone. All of the foregoing assumes you did not use a water soluble flux.

John

I have been able to remove all kind of flux residual with denaturated ethanol up to now. It has a slightly higher activity than IPA, I think. Acetone is clearly stronger, but I experienced it to attack some plastic materials used in electronic components, e.g. ABS buttons of a keyboard. Applying it in a mixture may be more gentle.

Denatured alcohol is essentially absolute ethyl alcohol with denaturants added. As I recall, there are about 17 different formulas for denaturants in the USA, depending on end usage. Simple methanol used to be used, but that has fallen into disfavor because it can cause blindness. Thus, the modified denaturants that make you sick, but are unlikely to permanently harm you. Some of the denaturants could attack plastics like polystyrene. ABS may also be attacked, but is more resistant. Acetone will definitely attack such plastics.

I don't know for sure about the plastic used as windows in LED's, photodiodes, and such. When my board has such devices, I either do not completely immerse, or I use just absolute ethanol without the acetone.

John

Hewitson said:

Any particular brand you'd recommend?

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I've had good results with Techspray and Chemtronics wicks. It should be noted that solder wick deteriorates with age. The flux will absorb and react with atmospheric moisture and the copper can even oxidize in extreme cases.

Some people are so obsessive about having fresh flux on their braid that they use pieces of flattened coaxial shield braid dipped in flux or store their spare solder wick in airtight containers.

Thanks for the tips guys, much appreciated. Decided to give the denatured alcohol a try (we call it metho here), and much to my surprise all the residue was removed in a matter of seconds!

Now I'm having a bit of trouble removing the white residue that has been left behind. There's 2 sliding volume pots right below the area, so I can't run it under the tap as I'd normally do. I think I'm going to buy a spray bottle and give it a spray/scrub with some water and let it run vertically off the board so it doesn't come into contact with these components.

I'll never buy non-no clean wick again, that's for sure.

If you are going to wash PCBs in running water, a better solvent is Electrolube ULC (Ultraclens) which I think uses an aromatic turpene based chemicals. It dissolves grease and flux but leaves them in an oily film which is water soluble. I've used it to clean fingerprints from plain copper board before making PCBs and also in one extreme case to recover an assembled board that had fallen off the conveyor in a wave soldering machine and dropped in the flux bath. That board was almost a solid chuink of hard flux, ULC followed by warm water completely recovered it.

Brian.

Well that worked brilliantly, the board is as clean as a whistle. I highly recommend metho plus a couple of rinses with water, very cheap and effective!

Brian: Wow, sounds like amazing stuff. I might have to invest in some of that, thanks for the suggestion

soldering pump will do the job