Components dissolved/damaged by flux cleaners?

[seanspotatobusiness]

Isopropanol was not dissolving my flux to clean it from a PCB so I bought toluene which was much more effective. I know that it dissolves some plastics and my question is can anyone list components which they know would be dissolved/damaged by contact with toluene? I've heard isopropanol dissolves certain components too and I know acetone will also dissolve some plastics. I've also heard that isopropanol can draw water into components due to its hygroscopic nature.

[Mick B]

You have to be kidding. DO NOT USE TOLUENE! unless you are using a respirator in a well ventilated area, that stuff will cause drain bamage   

[ogden]

You have to be kidding. DO NOT USE TOLUENE! unless you are using a respirator in a well ventilated area, that stuff will cause drain bamage   

Right. Even if you use respirator, better print 10-page material safety data sheet and place near your work area - so when someone find you (hopefully alive), they know what you are dealing with and how to help you:

H225 - Highly flammable liquid and vapour.
H304 - May be fatal if swallowed and enters airways.
H315 - Causes skin irritation.
H336 - May cause drowsiness or dizziness.
H361 - Suspected of damaging fertility or the unborn child.
H373 - May cause damage to organs (central nervous system, liver, heart) through prolonged or repeated exposure.
H402 - Harmful to aquatic life

Check the vital functions. Unconscious: maintain adequate airway and respiration. Respiratory arrest: artificial respiration or oxygen. Cardiac arrest: perform resuscitation. Victim conscious
with laboured breathing: half-seated. Victim in shock: on his back with legs slightly raised. Vomiting: prevent asphyxia/aspiration pneumonia. Prevent cooling by covering the victim (no warming up). Keep watching the victim. Give psychological aid. Keep the victim calm, avoid physical strain. Depending on the victim's condition: doctor/hospital. Never give alcohol to drink.

[tooki]

Come on, guys, every solvent's MSDS sounds like doom. And in cases of high concentrations and/or prolonged exposure (e.g. occupational exposure) I'm sure it's true. But for a bit of flux cleaning?!? Remember, toluene is also in tons of permanent markers…

Use it occasionally, in a well ventilated space, and you'll be fine.

OP: Often, a blend of solvents works best — which is exactly what commercial flux removers are. I have yet to encounter any component that gets dissolved by commercial flux remover (which is usually a blend of isopropanol, ethanol, and hydrocarbons like heptane). It does, however, melt the markings off of some diodes and resistors.

[Housedad]

God, how I miss 1,1,1-Trichloroethane.  You could clean anything with that stuff.  It would not touch plastics, but was hell on gook, rosin, and grease. I used it on my guns, cars, electronics, everything.  It was the perfect cleaning solvent.  Rosin would wash away and it would dry in under 10 seconds.   We lost the use of that in the 90's.

Along with belladonna extract. (Yes, the deadly nightshade)  When you had a stuffed up head from a cold, that stuff would dry up your sinuses and keep them dry.  When They advertised Contac pills would keep you dry fro 12 hours, they weren't kidding.  No antihistamine since has ever worked even 1/4 as well.  Took it away in the late 70's.



They always take away the things that work well.....

[ogden]

If flux cannot be dissolved with alcohol, you have to change flux, not cleaning agent! Stiff brush and Isopropyl + Ethanol 50:50 is all you need in most cases. I have great success using  Kontakt PCC flux remover - both solvent and brush works perfectly. As quick dry I use (flammable) "canned air" cleaner. Those two clean everything from pure rosin to modern no clean flux'es.

[jsantoro]

+1 for 1,1,1-Trichloroethane. When I was with IBM as a FE we used it for everything. Including cleaning your hands. No lasting damage so far....

[ogden]

+1 for 1,1,1-Trichloroethane. When I was with IBM as a FE we used it for everything. Including cleaning your hands. No lasting damage so far....

It was very good cleaning/smelling stuff indeed. Fun fact:

Ethanol lethal dose: 7340 mg/kg (oral, rat)
1,1,1-trichloroethane lethal dose: 9600 mg/kg (oral, rat)

[Cerebus]

If flux cannot be dissolved with alcohol, you have to change flux, not cleaning agent! Stiff brush and Isopropyl + Ethanol 50:50 is all you need in most cases. I have great success using  Kontakt PCC flux remover - both solvent and brush works perfectly. As quick dry I use (flammable) "canned air" cleaner. Those two clean everything from pure rosin to modern no clean flux'es.

Yes and no. I've found an awful lot of fluxes that have some component that's not soluble in non-polar solvents alone. The most likely culprit is some organometallic compound formed from reduction of metal oxides by the active components of the flux. The tell-tale giveaway is a slight white film or white rings left around joints that have been washed with just alcohol(s). I find that a mix of 70% isopropanol with 30% deionised water is the best universal cleaning solution. Usually followed by a deionised water rinse and a final rinse with 100% isopropanol (the latter mostly for its drying effect). If you're definitely going to rinse after cleaning then a drop or two of some surfactant (such as SDS) in the initial isopropanol-water cleaning mix helps.

[T3sl4co1l]

Correct: fluxes work by forming soluble salts of the metal oxides on the surface, thus allowing the metals to flow smoothly as they like.  (This would all be so much easier in inert gas or vacuum -- indeed it is, I've done induction brazing this way -- such a beautiful sight, no flux needed at all, just start with clean parts!)

I strongly suspect the best cleaner is either a mild acid or base: base to clean up the residual rosin (which is an organic acid), or acid to break up the soaps (organic salts of metals).  A solvent and detergent fraction keeps things suspended and dissolved.  A complexing agent (throw in some EDTA??) might be effective, too.

My opinion of white residue, is that it's just not fully cleaned.  Any solvent left on the board, has some rosin dissolved in it, which crystallizes out when it dries.  The only way to prevent this is with a constant flow of pure distilled solvent: a vapor degreaser.  The best you can approximate this without an explosion-waiting-to-happen, is with several washes of clean solvent, blow-drying the board inbetween (not to evaporate the solvent, but to blow it away while still liquid!)

And yeah, having the right solvent mix I'm sure accounts for a lot.  70% IPA evaporates to leave water, which will bead up and leave a speckled residue pattern.  Not necessarily a reason to use 100% of something, because the polarity of water probably helps a lot too.

Ah well, fun stuff, chemistry.  Unfortunately, doing more than armchair "research" (like, you know, anything actually useful to discuss.. ) is rather difficult.  One would suppose -- hope? -- that industrial flux cleaners have done this research, so that the best suggestion would be simply to buy one of those, and enjoy the ease of use, at a modest cost hike over generic solvents.

FYI: toluene is not particularly harmful.  Worse than acetone, say -- certainly, but it's not benzene (which you most definitely won't see at the hardware store).

Personally, I find ethanol, IPA, acetone and MEK quite suitable for the fluxes I use, without being too much trouble for the components I use.  I would not recommend toluene, petroleum ether, mineral spirits or the like: nonpolar and aromatic solvents tend to dissolve many more plastics than these light polar solvents do.  Even so, there are plenty of components affected, most often the ink labels on capacitors (electrolytics and film caps for example).

Tim

[David Hess]

Some soldering irons now shield the tip and work with blown nitrogen from a nitrogen generator.

[seanspotatobusiness]

You have to be kidding. DO NOT USE TOLUENE! unless you are using a respirator in a well ventilated area, that stuff will cause drain bamage   

Right. Even if you use respirator, better print 10-page material safety data sheet and place near your work area - so when someone find you (hopefully alive), they know what you are dealing with and how to help you

Neither of you have any idea what you're talking about.

[schmitt trigger]

Carbon Tetrachloride, anyone?
Of course not. CCl4 is both very powerful AND very dangerous. 

[ogden]

Neither of you have any idea what you're talking about.

We are at least talking. Did you already use toluene?

[GreyWoolfe]

I use MG Chemical 835 rosin flux.  I use 99.995% IPA and a toothbrush and scrub the residue off.  Another scrub with the IPA and then a light wash with the IPA.  Does a great job of cleaning up after myself.

[David Hess]

A 50/50 mix of isopropyl alcohol and toluene is a common rosin flux thinner.  But I am not sure if toluene is any better than acetone as far as damaging plastics and acetone is apparently safer.

[Jeroen3]

This stuff, called Cramolin Fluxoff, https://nl.rs-online.com/web/p/flux-removers/1115843/ does the job best from all solvents found.
It does not damage plastics, but it does ruin some paints. And also stickers are doomed.

Is it 30% isopropanol, 30% of "a complex mixture of hydrocarbons", 20% n-butyl acetate and some other stuff.
It's bad for you, use only in vented cabinet.

[Mechatrommer]

Neither of you have any idea what you're talking about.

We are at least talking. Did you already use toluene?

yes you know how to talk. we know how to deal with toluene (thinner), infact i used up more than 2kg of it during these few days without respirator mask just as many times before, not to show heroism but to show i'm still around. thinner is several magnitude better at dissolving/cleaning things compared to Isopropanol alcohol (medical spirit), yes i have them and acetone too. the only thing i dont like about thinner is it leave sticky layer on the pcb when dried, but i cant find any better dissolver/cleaner. the trick is to wipe with tissue, cloth fabric or something before they dried and we get shiny as new pcb. to the OP, assume any plastic will be dissolved by the toluene (including few layers of your thin skin no pun intended), but not all, you have to test it yourself, but afaik its not harmfull to other electronics components. otoh, more damage have been done by people consuming alcohol (the beer, which is recommended by most) than people using toluene.

[Keicar]

In the unlikely event that you're using polystyrene capacitors, you'd need to be extra careful with solvent usage - as they're pretty easy to damage, as I recall.

[Mick B]

Go into a bathroom with a can of Toluene pour some on a rag, then wait minuets, you will definitely be impaired, it is akin to sniffing glue. Toluene is the ingredient in glue that makes people high, perhaps that is why some people are advocating it's use. It is a proven fact it causes Brain damage. I said a bathroom so the results would be almost immediate, In a larger enclosure not well ventilated cleaning a large board might be enough time to impair oneself. Anyone thinking of using Toluene you have been warned, there are safer and less dangerous methods to clean flux.           

[Cerebus]

Go into a bathroom with a can of Toluene pour some on a rag, then wait minuets, you will definitely be impaired, it is akin to sniffing glue. Toluene is the ingredient in glue that makes people high, perhaps that is why some people are advocating it's use.

Really? You're on your 12th ever message on the forum and you think it's a good idea to make snide remarks at its inhabitants? Early, casual use of insulting speech towards other people is a pretty good indicator of people who get banned in the end. To quote yourself "you have been warned".

As to the substance, what little there is, of your message I think everybody here is quite aware of the dangers of using any solvent in a confined space without adequate ventilation. That's pretty much the first warning label on any bottle of solvent. That you start out your argument by suggesting doing exactly what would be regarded by anybody as stupid behaviour, seeking out a confined poorly ventilated space to work in, is an indication of how weak and poorly thought out your argument is.

If one looks at the MSDS for isopropanol and toluene side by side they are almost identical in all the critical places, the only thing that stands out is that the toxicity levels for toluene are broadly 2-10 times higher (i.e. 1/10 - 1/2 the dose) than for isopropanol. In the case of both, in the warning diamond the fire risk gets top billing with a 3, with toxicity coming second, a 2 for toluene and a 1 for isopropanol. Both contain warnings of Central Nervous System toxicity but secondary to liver and kidney toxicity. For what it's worth the MSDS for Ethyl Alcohol would carry a CNS toxicity warning, but we drink beer and use isopropanol as a food additive. The mere presence of a toxicity warning on the MSDS for a substance does not mean that it is a 'deadly poison' in that regard.

So all the fuss about toluene's toxicity is (1) exaggerated, (2) less than the risk from burning yourself or your workshop down and I don't see a great  about that.

Rather than listen to ill-informed scaremongering I suggest people read the material safety data sheets for themselves, I've attached them. It's all pretty irrelevant in context anyway as I would say, based on personal experience and all the materials compatibility charts that I've seen over the years, that toluene is a very poor choice of cleaning solvent in a mixed plastics environment as it has poor compatibility with the majority of plastics used in electronics.

[IanMacdonald]

Point to note about isopropanol is that it causes synthetic rubber to swell up.

The effect may take weeks to show, so the cause and effect of the equipment seizing up might not be recognised.

[james_s]

I have a can of toluene in my garage, breathing the fumes is not good for you, neither is breathing gasoline/petrol fumes but hundreds of millions of people use that every day. It's common sense that you use these sort of things in a well ventilated area and avoid breathing the fumes or getting the stuff on your body. Doesn't mean you'll drop dead if you look at the stuff.

[Cerebus]

Point to note about isopropanol is that it causes synthetic rubber to swell up.

That's entirely plausible, many solvents do that to varying degrees - methyl ethyl ketone is sold to the offset litho printing industry as 'blanket restorer' precisely because it makes rubber printing blankets bounce back to their prior thickness after they've been on press for a few hours.

The effect may take weeks to show, so the cause and effect of the equipment seizing up might not be recognised.

That's not so plausible. It may happen immediately while still in contact with the solvent but it won't happen weeks later after the solvent has evaporated. Common sense says that any effect is caused by solvent penetration so either it penetrates and causes the effect as it does so, or it evaporates and isn't there to have any effect whatsoever. If you think differently then please cite the mechanism of action with references to a reliable source that explains it - there's enough "heard it from a bloke down the pub" physical chemistry in this thread without adding more.

[ogden]

If you think differently then please cite the mechanism of action with references to a reliable source that explains it - there's enough "heard it from a bloke down the pub" physical chemistry in this thread without adding more.

Here you go:

https://www.britannica.com/science/polyacrylate

[edit] Mechanism does not even need citation - imagine canister with alcohol inside, it's lid with rubber seal. First week you will not notice that seal disintegrates. It takes more than that. BTW exactly that happened with seal of my "lo cost" gas canister, in one year. Here we have alcohol additives in generic gasoline.