Strongest flux remover

[mladen82]

Hello everyone!
I doing some repair&rework with electronics and until now i used isopropyl alcohol for cleaning flux residues from soldering, but  realized that i need a stronger cleaner for harder baked-on flux residues.
So i bought Microcare Vericlean flux remover (aerosol) but i was dissapointed with results, even worse than isopropyl. Let assume that i bought weaker Microcare flux remover, they have stronger removers also but there are many other manufacturers also (Techspay, MG Chemicals, Chemtronics, ACL Staticide,3M, Electrolube and others ) and other formulated  flux removers (chemical ingredients).

So my question is anyone tried some good strong flux remover for manual use as i don't want to make mistake again.

Thanks in advance.

[German_EE]

Careful use of acetone may work but please be aware that this will attack some plastics. Failing that, go back to IPA but use an ultrasonic cleaning bath.

[ChristofferB]

Careful use of acetone may work but please be aware that this will attack some plastics. Failing that, go back to IPA but use an ultrasonic cleaning bath.

I agree. Acetone dissolves it all, but unfortunately, also epoxy, so your PCB may suffer a bit. At the very least it might give an ugly finish.

[N2IXK]

DCM does a decent job of removing old baked on flux, but is toxic, and even worse on plastics than acetone.  Use only in a well ventilated area or outdoors.

[David Hess]

I would use acetone or lacquer thinner.  For something a little less aggressive and less expensive, you might also try mixing acetone with IPA.

[Someone]

This stuff will take 'most anything off without damaging boards or components:
http://www.electrolube.com/products/cleaning/swas/safewash_range_-_aqueous_cleaning/
They have less aggressive options but gloves and safety glasses are needed for most of the rapid cleaners.

[cat87]

Unfortunately, nowadays, almost all commercial PCB cleaning  products are useless. This is because of all that eco-friendly stuff, that's going around. For industrial Branson cleaners, you could get some really nice solvents that  did away with the flux in about half an hour. But after those were considered to be carcinogenic, they were replaced with something resembling tap water, that's eco-friendly and triple the price of course....and of course they didn't work, meaning that the PCBs had to be soaked in the stuff for about 3-4 hours.

As mentioned in other posts, the really cool stuff is either IPA or DCM. Acetone, not so much, because depending on the components you have and the PCB itself, things might 
Of course, for making these even more effective, the aforementioned chemicals should be used with  an ultrasonic bath or the classic paper towell and brush.

[Conrad Hoffman]

Be sure you go to the capacitor sites and look at the application/tech data for al e-caps. They're usually pretty specific about what you can expose both regular and solvent-resistant caps to. Get a few of the wrong molecules in there, and they degrade pretty quick. I use IPA and a tooth brush and most boards come clean after a few minutes. I've used stronger solvents on things like old Dynaco boards that seemed to be dipped in flux, but keep the wet time to a minimum and use compressed air to get the stuff out from under parts and anywhere else it can hide. Most boards get a soap and water cleaning, rinse and compressed air dry after that.

Be careful with clear wrapped polystyrene caps too. They may look fine, but then craze and fail days or weeks later after solvent exposure.

Decades ago we used some aerosol products that were probably methylene chloride or some other horrible stuff. They were deadly but sure worked great. Freon TE-35 was also great stuff and didn't touch plastics, but destroyed the ozone layer.

[wilhelm]

I use a 1:1 mix off acetone and IPA. Or add acetone in the IPA untill you get a good removal.

[Pjotr]

For real hard baked flux I use methylene chloride. A tad bit more aggressive stuff than acetone but less flammable Used with care in a well ventilated room or fume-cupboard it isn't that dangerous, but ok, it is no stuff to work whole day with like those diy surf board guys do. Acetone and methylene chloride can dissolve some plastics but most electronic PP, PE, phenol and epoxy based parts have a good resistance to it. Occasionally some kinds of solder masks will weaken, especially those older laminated-on ones. Modern (Chinese) one doesn't bother. So be careful and try first and wear protective gloves!

[nanofrog]

I home brew mine.

Primarily it's just denatured alcohol (Kleen Strip brand I buy is ~50/50 mix of ethanol & methanol). But if I need something more aggressive, I add 20% xylene by volume, and in a pinch, I add some acetone if needed. And all of this stuff can be found in a local paint department/store.

[KL27x]

Strongest flux remover depends on the flux. (+1 on acetone and IPA mix, though, for general use) And a small paint brush with the bristles cut down. Or a toothbrush.

[CraigHB]

I just drop my boards in a tub of IPA and brush away the baked on crud with a flux brush.  For stubborn flux residue I use contact cleaner.  Works well for me so that's what I stick with.  I keep a container of acetone to use when I need it, but it evaporates really fast and is highly flammable.  Don't really like it for cleaning, mainly use it as a solvent for cyanoacrylate glue.  It also eats some plastics.  I'd be concerned with it possibly going after component packages.  I haven't heard of using this DCM stuff, will have to look it up.

[nanofrog]

I haven't heard of using this DCM stuff, will have to look it up.

DCM = dichloromethane (or methylene chloride). Based on my knowledge, it's usually the primary ingredient in chemical paint strippers and some degreasers, as well as used as a welding agent for some plastics.

And according to Wikipedia, it's also used as a decaffeinating agent for coffee and tea. 

[Pjotr]

Another tough cleaner when IPA doesn't help is "PVC cleaner", i.e. Tangit PVC-U/C ABS from Henkel. It is primarily used for cleaning PVC plumbing pipe before cementing. Available from most DIY stores. It is a mixture of acetone and butanon (also known as MEK). Same precautions hold as for acetone and methylene chloride.

[timb]

Butane works as well for spot cleaning lumps of old flux, but be careful if you're applying it from a pressurized can, as it will come out *very* cold, which can potentially damage some types of electrolytic capacitors and also give you frostbite.

It evaporates quickly and is obviously flammable, so use it in a well ventilated area! (Many years ago I watch someone light up a cigarette while attempting to make BTHO [Butane Hash Oil]; he spent weeks in a burn unit and required several skin grafts.)

[helius]

Chemtronics Max-Kleen Lectro-Solv is probably the strongest plastic-safe flux remover. It also seems to be discontinued, as trichloroethylene is believed to cause cancer.
You can find the similar, but slightly less powerful tetrachloroethylene in several cleaners such as CRC Brakleen and Lectra-Motive. I don't know if they are specified to be safe on plastics.

[Someone]

Unfortunately, nowadays, almost all commercial PCB cleaning  products are useless. This is because of all that eco-friendly stuff, that's going around. For industrial Branson cleaners, you could get some really nice solvents that  did away with the flux in about half an hour. But after those were considered to be carcinogenic, they were replaced with something resembling tap water, that's eco-friendly and triple the price of course....and of course they didn't work, meaning that the PCBs had to be soaked in the stuff for about 3-4 hours.

As mentioned in other posts, the really cool stuff is either IPA or DCM. Acetone, not so much, because depending on the components you have and the PCB itself, things might 
Of course, for making these even more effective, the aforementioned chemicals should be used with  an ultrasonic bath or the classic paper towell and brush.

Get in contact with electrolube, they have a range of cleaning solutions that will take off flux in minutes.

[Cerebus]

Another tough cleaner when IPA doesn't help is "PVC cleaner", i.e. Tangit PVC-U/C ABS from Henkel. It is primarily used for cleaning PVC plumbing pipe before cementing. Available from most DIY stores. It is a mixture of acetone and butanon (also known as MEK). Same precautions hold as for acetone and methylene chloride.

Be aware that MEK (Butanone, Methyl-Ethyl-Ketone) is strongly absorbed by some plastics, causing them to swell. It was (is?) sold to litho printers as "blanket restorer" for putting a bit of bounce back into tired rubber printing transfer blankets and is the only thing I know that will remove hardened, long dried printing ink. Used judiciously it is an excellent solvent. It is significantly higher fire risk than acetone - it has vapour creeping qualities similar to ethyl ether.

[T3sl4co1l]

The best possible ones will be the most toxic or flammable ones.  Needless to say, they will likely affect components or board materials...

DCM: swells or dissolves almost every organic polymer, including epoxy and silicone.  Best avoided.
Light ethers (usually diethyl ether): probably fine, but highly flammable and an organic peroxide hazard (if you see crusty deposits in the bottle... call the bomb squad).
Light CFCs: chloroform (anesthetic), carbon tetrrachloride (carcinogenic), trichloroethylene, 1,1,1 trichloroethane, others.  TCEs in particular are exceptional (leaving most plastics alone, similar to acetone), but have fallen out of use because, you know, the ozone layer and such...
Acetone, ethanol, isopropanol: not as strong, but leaves most plastics alone, and are environmentally friendly and low-toxicity (if still rather flammable).

IPA with base and surfactant: usually detergent and ammonia.  Rosin is organic acid, so this is a killer combination!  (This is probably most of what that SafeWash stuff is.)

Heating, agitation (or better yet, sonication), and multiple wash-rinse cycles will do the best job.

Mind that you can't really wash under flat-mounted chip components.  If you need very low leakage, consider routing slots under those spaces, or adding vent holes/vias to allow solvent through.

Also try not to cook the piss out of the rosin.  The longer you keep it hot (and the dirtier your metal surfaces are), the more insoluble (or slowly soluble) gunk it leaves.

Tim

[calexanian]

As i just mentioned in another post. Non chlorinated brake cleaner can remove the most baked on RA flux. Like any solvent some parts may melt or become discolored. Brake cleaner, toothbrush, and a flush with deionized water and you have the cleanest board you ever saw.

[David Hess]

Light CFCs: chloroform (anesthetic), carbon tetrrachloride (carcinogenic), trichloroethylene, 1,1,1 trichloroethane, others.  TCEs in particular are exceptional (leaving most plastics alone, similar to acetone), but have fallen out of use because, you know, the ozone layer and such...
Acetone, ethanol, isopropanol: not as strong, but leaves most plastics alone, and are environmentally friendly and low-toxicity (if still rather flammable).

TCEs were great for flux removal.

Toluene mixed with isopropanol may be better than acetone mixed with isopropanol and is or was a common flux thinner (I have a bunch of bottles of 50/50 toluene/isopropanol intended as such) but I did not suggest it because the availability of toluene has become restricted.  This suggests that xylene which is readily available mixed with isopropanol would also be good for rosin flux removal (and thinning) but I have not tried it.

[CraigHB]

Good thing about CRC Brakleen is it's super cheap, seeing it for like five dollars a 20 oz spray can shipped on eBay.  I use CRC QD Electrical Cleaner when IPA can't get residues.  It's better than twice the cost of CRC Brakleen.  The QD Electrical Cleaner does work well, but it's a bit pricey and I go through it kind of fast.  Looking on the label it says it contains Hexane, Ethanol, and Diflouroethane.  What's in Brakleen?

[darrellg]

Trichloroethane is the best, if you don't mind that it's mildly toxic and illegal under the Montreal Protocol.

[N2IXK]

Good thing about CRC Brakleen is it's super cheap, seeing it for like five dollars a 20 oz spray can shipped on eBay.  I use CRC QD Electrical Cleaner when IPA can't get residues.  It's better than twice the cost of CRC Brakleen.  The QD Electrical Cleaner does work well, but it's a bit pricey and I go through it kind of fast.  Looking on the label it says it contains Hexane, Ethanol, and Diflouroethane.  What's in Brakleen?

CRC Brakleen comes in 2 varieties, the green can that contains perchloroethylene, and the red can, which is a mix of acetone, toluene, and methanol.