PCBONEZ wrote:

It is an alcohol = organic. […]
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feipoa wrote:

PCBONEZ wrote:

The Isopropyl flush will remove small amounts of oil.

I thought Isopropyl was an inorganic solvent.

It is an alcohol = organic.

It's one of the few solvents approved for use in piping associated with primary coolant in nuclear plants exactly because it's so effective at removing contaminants and it doesn't leave any residue. Most of the other approved solvents are Freon based so they are more problematic to use. Stuff like trichlorotrifluoroethane although I don't recall if that's one of the approved ones for those pipes.

feipoa wrote:

Are the oils in those compressed air cans organic or inorganic? I usually think of "oil" as organic.

Also organic. (Fossil based.)

From the MSDS for the CC-CT brand brought up earlier. (That appears to be edited out now.)
iso-Hexanes >60%
n-hexane <5%
hydrocarbon propellant 10-30% (I read somewhere that the propellant is usually butane.)

Other brands no doubt have similar stuff in them.

.
n-hexane is a known neurotoxin so frequent use or use indoors is not a grand idea IMHO.
.

Sorry, when I wrote "inorganic" solvent I meant that it does not dissolve organic material well, not that the solvent does not contain organic constituents. I recall my professors in graduate school always making a point to not use ISO to clean the finger prints or other oils off our gold nano arrays because it was "not an organic solvent." Were they wrong? Or are you wrong? I am confused. I recall the protocol was to use acetone to clean off the oils, then use ISO to clean off the acetone. Sometimes we also used a "piranah etch" instead of the acetone (sulfuric acid + hydrogen peroxide).

So my understanding was that if you are going to use ISO to clean oils (i.e. for materials which will be eaten by the acetone), that pressure needs to be used to sheer the oil away or that the oil needs to be picked up, for example by a q-tip or similar. Unfortunately, that can leave scratches, hence the need for an "organic solvent", like acetone. I think I will do a little experiment tomorrow with some wheel bearing grease in a dish to see if ISO dissolves it at all. Then compare it with acetone.

PCBONEZ wrote:

The chlorine does not leave a residue that I know of. The magnesium and calcium do. Looks like the cloudy blotches or streaks li […]
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ramiro77 wrote:

Although I never saw residues of chlorine left on my boards. How do you detect it? I remember seeing some white residues between pins on chipsets or pins that are very close to each other, but that looked more like calcium deposites. I never found out what it is.

The chlorine does not leave a residue that I know of. The magnesium and calcium do.
Looks like the cloudy blotches or streaks like you might see on dishes that air dried with a trace of soap still on them.

The white stuff near groups of pins looks about the same and could be that or due to reactions with residual flux or lead.
The lead based residues are not always water soluble whereas the magnesium/calcium salt residues are.
Seems to be more common with lead free solder which is too new I think for this paper to cover.
http://www.kester.com/kester-content/uploads/ … ite_Residue.pdf
.

I'm sorry. I did understand you wrong. I thought you were saying that you saw residues of chlorine on motherboards. My bad.
About the residue: I saw that on my 95' FIC motherboard after washing. I don't know if that residue was there before washing becasue I didn't pay attention to it. I can assume my motherboard isn't lead free as it's too old.

Where I live the water is very clean and leaves no residue, I mostly use hot water to clean boards. If I want to test a board after I have cleaned it I just dry it in the oven at 75C for a couple of hours.

When water isnt enough I use White Gas as I often find ISOpropanol too weak when it comes to dissolving tar.

feipoa wrote:

PCBONEZ wrote:

From the MSDS for the CC-CT brand brought up earlier. (That appears to be edited out now.) iso-Hexanes >60% n-hexane <5% hydroca […]
Show full quote

From the MSDS for the CC-CT brand brought up earlier. (That appears to be edited out now.)
iso-Hexanes >60%
n-hexane <5%
hydrocarbon propellant 10-30% (I read somewhere that the propellant is usually butane.)

Other brands no doubt have similar stuff in them.

.
n-hexane is a known neurotoxin so frequent use or use indoors is not a grand idea IMHO.
.

Sorry, when I wrote "inorganic" solvent I meant that it does not dissolve organic material well, not that the solvent does not contain organic constituents. I recall my professors in graduate school always making a point to not use ISO to clean the finger prints or other oils off our gold nano arrays because it was "not an organic solvent." Were they wrong? Or are you wrong? I am confused. I recall the protocol was to use acetone to clean off the oils, then use ISO to clean off the acetone. Sometimes we also used a "piranah etch" instead of the acetone (sulfuric acid + hydrogen peroxide).

So my understanding based on my time in graduate school was that if you are going to use ISO to clean oils (i.e. for materials which will be eaten by the acetone), that pressure needs to be used to sheer the oil away or that the oil needs to be picked up, for example by a q-tip or similar. I think I will do a little experiment tomorrow with some wheel bearing grease in a dish to see if ISO dissolves it at all. Then compare it with acetone.

I think your professors might have breathed too much acetone. Was it a party school? (teasing)
There may be isolated cases with specific materials where acetone is better but in general I think it's a bad idea.
Acetone dissolves some PCB materials and plastics and it's a health and fire hazard. We did not keep it on-hand.
Using ISO was the preferred procedure in our electronics tech manuals for post soldering and for casualty cleanups.
Some of our PCBs were 1/2 the size of a 2.5" drive PCB but cost more than a 3 Br house so straying from written procedures was not a great idea if you weren't into peeling potatoes.

If you read through what I wrote the ISO is used to clean trace levels of whatever after a detergent has been used for anything heavy.
The force of the spray is adequate agitation for anything left post detergent and you aren't picking it up you are flushing it off.
Think like spraying leaves off the porch with a hose. The leaves don't dissolve but they do flush off.
That is why I used the word flush.

As to cleaning up after compressors. That was about trace amounts or tiny drops. Flushing by the force of the ISO spray is adequate.
If your compressor is sputtering so much oil you can easily see drops on a PCB then you need a new compressor and/or you have contaminated hoses.
My big compressor does that but it's 30 years old.

I've been using Isopropyl for years to:
Final clean up of brake drums and rotors.
Final wipe to clean off finger prints prior to painting.
Cleaning gasket surfaces prior to applying the sealer.
Finger prints on glass, tile, chrome.
and similar.
Most of those are done by wiping with a saturated rag or paper towel so the rag or towel does the 'picking up' and it works.
.
.
I don't see the point of your bearing grease experiment. Even gasoline won't dissolve a lump of grease without help.
.

ramiro77 wrote:

About the residue: I saw that on my 95' FIC motherboard after washing. I don't know if that residue was there before washing becasue I didn't pay attention to it. I can assume my motherboard isn't lead free as it's too old.

I think so.
The first RoHS directive was in 2002 but the Commission came to exist in late 2000.
1995 seems too early even for those that started early.
.
Both leaded and lead free solder will do it though.
There are a lot of different solder and flux formulations so it's hard to say exactly what it is left on any given board.
I've just noticed in doing things that lead free boards that were probably wave-soldered seem to be prone to it, especially in areas with lots of pins.
.

One of the better cleaners I've ever used or heard of is actually ether (starter fluid). It's a trick passed down by old school mechanics. I'm not too sure how compatible it would be with electronics, though.

Skyscraper wrote:

Where I live the water is very clean and leaves no residue, I mostly use hot water to clean boards. If I want to test a board after I have cleaned it I just dry it in the oven at 75C for a couple of hours.

When water isnt enough I use White Gas as I often find ISOpropanol too weak when it comes to dissolving tar.

This is one of those things that can work great in one geographical location but not so much in another.

My reservations about heating PCBs that much is that heat ages capacitors and 75C is too close to 85C which is the rating for many electronics parts and there are even some only rated for 75C.
Depending on the weather there is also a chance of condensation forming on the PCB as the board cools off which would defeat the purpose. I dunno if that's even an issue where you live. When I lived far North of here it was.

75C for a couple of hours probably won't do anything seriously bad but it doesn't give me a warm fuzzy either.

I have to admit though that I did use an oven at 65C a few times when I was experimenting with what works best for me.
65C (150F) was the lowest possible setting on that oven and I left the door half open for airflow so it wouldn't actually be at 65C.
It works. I just don't prefer it.

Do you mean White Gas as in stove fuel (which is naphtha) or as engine fuel (which is gasoline with no additives)?
.
How exactly do you get tar on a motherboard?
.

gdjacobs wrote:

One of the better cleaners I've ever used or heard of is actually ether (starter fluid). It's a trick passed down by old school mechanics. I'm not too sure how compatible it would be with electronics, though.

Starting fluid is usually ether based.
Never thought about trying that.
[Edit]
I just remembered that stuff melts/softens the hard black plastic covers on chokes (the kind on carburetors) so I don't think I'm going to try it for electronics.
.

More info on cleaning in this thread: first time someone suggested to me I put boards in the dishwasher I thought they were winding me up! The first time you hear it it's a bit like "Nahhhhh... that'll never work!", but the more people say they've done it, the more you start to believe.

I'm still yet to engage in the practice myself.

Love the way the guy in the OP's video gets out the Mr Muscle like it's magical stuff - reminds me of the dad from My Big Fat Greek Wedding who sprays Windex on everything.

PCBONEZ wrote:

This is one of those things that can work great in one geographical location but not so much in another. […]
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Skyscraper wrote:

Where I live the water is very clean and leaves no residue, I mostly use hot water to clean boards. If I want to test a board after I have cleaned it I just dry it in the oven at 75C for a couple of hours.

When water isnt enough I use White Gas as I often find ISOpropanol too weak when it comes to dissolving tar.

This is one of those things that can work great in one geographical location but not so much in another.

My reservations about heating PCBs that much is that heat ages capacitors and 75C is too close to 85C which is the rating for many electronics parts and there are even some only rated for 75C.
Depending on the weather there is also a chance of condensation forming on the PCB as the board cools off which would defeat the purpose. I dunno if that's even an issue where you live. When I lived far North of here it was.

75C for a couple of hours probably won't do anything seriously bad but it doesn't give me a warm fuzzy either.

I have to admit though that I did use an oven at 65C a few times when I was experimenting with what works best for me.
65C (150F) was the lowest possible setting on that oven and I left the door half open for airflow so it wouldn't actually be at 65C.
It works. I just don't prefer it.

Do you mean White Gas as in stove fuel (which is naphtha) or as engine fuel (which is gasoline with no additives)?
.
How exactly do you get tar on a motherboard?
.

If Im in no hurry I use 50C or let the boards dry in ambient temperature. Condensation is a factor during the summer here but not during the winter.

The White Gas I use is Heptane based, the name for this type of White Gas in Sweden is "Technical Gas" or in Swedish "Teknisk Bensin".

https://en.wikipedia.org/wiki/Heptane

Here is a picture showing the bottle of the brand I use. This stuff leaves no traces at all but it isnt very nice to paper labels.

Skyscraper wrote:

The White Gas I use is Heptane based, the name for this type of White Gas in Sweden is "Technical Gas" or in Swedish "Teknisk Bensin".

https://en.wikipedia.org/wiki/Heptane

Here is a picture showing the bottle of the brand I use. This stuff leaves no traces at all but it isnt very nice to paper labels.

I don't think I've ever come across that stuff. Might not even be legal to the public here.
Looks like it's not something you would want to use indoors.
.

PCBONEZ wrote:

I don't think I've ever come across that stuff. Might not even be legal to the public here. Looks like it's not something you wo […]
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Skyscraper wrote:

The White Gas I use is Heptane based, the name for this type of White Gas in Sweden is "Technical Gas" or in Swedish "Teknisk Bensin".

https://en.wikipedia.org/wiki/Heptane

Here is a picture showing the bottle of the brand I use. This stuff leaves no traces at all but it isnt very nice to paper labels.

I don't think I've ever come across that stuff. Might not even be legal to the public here.
Looks like it's not something you would want to use indoors.
.

I only use small amounts for cleaning CPUs and to wipe very dirty cards or motherboards, the smell is very nice so it's likely not a good idea to use larger quantities without good ventilation. The price for this Heptane based White Gas is ~$8 for a litre (quarter gallon in gibberish) so its too expensive to use in large quantities anyhow.

PCBONEZ wrote:

Starting fluid is usually ether based. Never thought about trying that. [Edit] I just remembered that stuff melts/softens the ha […]
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Starting fluid is usually ether based.
Never thought about trying that.
[Edit]
I just remembered that stuff melts/softens the hard black plastic covers on chokes (the kind on carburetors) so I don't think I'm going to try it for electronics.
.

I looked up rubber resistances. It looks like rubber interactions for diethyl ether would be similar to heptane or naptha. I think any continuous exposure would be a bad idea, but fortunately ether evaporates extremely rapidly. It may be worth testing.
http://mykin.com/rubber-chemical-resistance-chart

The biggest thing with ether is to never use it indoors. It's phase volatility and ignition properties mean that any enclose space will basically be a fuel air bomb if used inside.

brassicGamer wrote:

More info on cleaning in this thread: first time someone suggested to me I put boards in the dishwasher I thought they were winding me up! The first time you hear it it's a bit like "Nahhhhh... that'll never work!", but the more people say they've done it, the more you start to believe.

I'm still yet to engage in the practice myself.

I've had acquaintances that did the dishwasher thing regularly and I've tried it myself a few times too.

It works pretty good. (Not an option where I live now for *I AM* the dishwasher.)

I have never done it with pin-in-socket boards like socket 775 and i don't think I would.

The way I finally settled on for that was to spray down the boards heavily with a strong spray bottle detergent (like Mean Green) then run it with hot water without adding soap as you would for dishes. If the washer has a heat cycle at the end I either don't use it or let it run no more then 5 minutes. Then I pop the door open while everything is still hot and let them air dry. If that hasn't worked by an hour (due to weather/humidity or whatever) I pull them out and do it the dry with Isopropyl way and hang them somewhere to dry.
- Couple notes on placement. (As much as possible.......)
I put them around the perimeter and lean the component side towards the center sprayer.
If it's in the top tray place it component side down and try to get a slope on it.
The I/O panel connectors should go down or down-ish so spray hits them and they don't collect water.
Don't try to do too many at the same time. Want a good space between them.
You can use clean dishes/glasses for props and stands if needed.

----
I've also done keyboard keys in with the regular dishes by putting them in a mesh basket.
Spray them with detergent first also.
Put something heavy over the top so they don't get blown out of the basket.
.

gdjacobs wrote:

I looked up rubber resistances. It looks like rubber interactions for diethyl ether would be similar to heptane or naptha. I thi […]
Show full quote

PCBONEZ wrote:

Starting fluid is usually ether based. Never thought about trying that. [Edit] I just remembered that stuff melts/softens the ha […]
Show full quote

Starting fluid is usually ether based.
Never thought about trying that.
[Edit]
I just remembered that stuff melts/softens the hard black plastic covers on chokes (the kind on carburetors) so I don't think I'm going to try it for electronics.
.

I looked up rubber resistances. It looks like rubber interactions for diethyl ether would be similar to heptane or naptha. I think any continuous exposure would be a bad idea, but fortunately ether evaporates extremely rapidly. It may be worth testing.
http://mykin.com/rubber-chemical-resistance-chart

The biggest thing with ether is to never use it indoors. It's phase volatility and ignition properties mean that any enclose space will basically be a fuel air bomb if used inside.

It's not rubber you need to worry about it's plastics.
The resins use various solvents and if you dunno what they all are then using things like ether, heptane or naptha can be risky.
Might work just fine on a bunch then you get one and it's ruined because some different plastic was used.
.

PCBONEZ wrote:

It's not rubber you need to worry about it's plastics. The resins use various solvents and if you dunno what they all are then u […]
Show full quote

It's not rubber you need to worry about it's plastics.
The resins use various solvents and if you dunno what they all are then using things like ether, heptane or naptha can be risky.
Might work just fine on a bunch then you get one and it's ruined because some different plastic was used.
.

I was thinking of heat shrink and the bottom seal on electrolytics, but you're right. Even sockets and IC packages could potentially be damaged.

I still think the only sure way to check is to test, probably do repeat exposures until there's evidence of component failure. Ideally on an unstable circuit design.

feipoa wrote:

Sorry, when I wrote "inorganic" solvent I meant that it does not dissolve organic material well, not that the solvent does not contain organic constituents. I recall my professors in graduate school always making a point to not use IPA to clean the finger prints or other oils off our gold nano arrays because it was "not an organic solvent." Were they wrong? Or are you wrong? I am confused. I recall the protocol was to use acetone to clean off the oils, then use IPA to clean off the acetone. Sometimes we also used a "piranah etch" instead of the acetone (sulfuric acid + hydrogen peroxide).

So my understanding was that if you are going to use IPA to clean oils (i.e. for materials which will be eaten by the acetone), that pressure needs to be used to sheer the oil away or that the oil needs to be picked up, for example by a q-tip or similar. Unfortunately, that can leave scratches, hence the need for an "organic solvent", like acetone. I think I will do a little experiment tomorrow with some wheel bearing grease in a dish to see if IPA dissolves it at all. Then compare it with acetone.

The results of my tests were not entirely inconclusive, however based on what I have read online, acetone is quite a bit better at removing oils than Isopropyl. In my tests, neither IPA, nor acetone (by way of a nail polish remover bottle), would dissolve some petroleum-based grease in a dish. I used 99% IPA and my wife’s acetone-based nail polish remover. I’m not sure how the concentration of acetone in nail polish remover compares to lab grade acetone, but online suggests it can be 30-60%. Since the grease did not dissolve in IPA or acetone, my first thought was that if you simply soak your dirty parts in IPA and do not apply ample sheering force (from the squirt bottle) or apply physical contact to remove the grease, that the grease will remain on the surface after the IPA drys. Swishing the IPA around in the dish did not lift the grease from the surface.

The grease did appear IPA-phobic, that is, when I spread some bearing grease all over a glazed ceramic dish and stirred it with a stick, the grease would clump together into a single mass. However, even with the grease on a smooth surface, I had to use physical contact before the grease would lift from the surface of the dish. I am sure your results would vary depending on the type of grease (specific weight, constituents) and time/agitation.

I then proceeded to use some non-chlorinated brake cleaner. The grease dissolved pretty well in this case. An online search revealed that non-chlorinated brake cleaners often contains heptane and acetone. Perhaps the concentration of acetone in my wife’s nail polish remover was too low to be effective.

Since you generally do not want to use acetone on PCB’s (damage to plastics and resins), I thought I would try some other cleaners to see how they were at dissolving my sample grease. I tried some citric acid and acetic acid, but the result was the same as with the IPA. Mean Green did an ok job at dissolving the grease, but not nearly as good as the brake cleaner.

I used a few different test samples: a thin layer of bearing grease, a thick blob of bearing grease, vasoline, 3-in-one oil general purpose hinge oil, and sunflower oil. The best case was the thin layer of red bearing grease because I could visualise it in a white ceramic dish.

Further debate on IPA vs. acetone for cleaning oils, if you are interested. http://www.eng-tips.com/viewthread.cfm?qid=85538 This comment in particular, “I've used both for cleaning/degreasing and find acetone to be far better at actually dissolving and stripping "grease" than IPA. Non-polar, non-water soluble solvents like toluene etc. are better still.” I used toluene once, it worked well. I’m not sure how easy that is to get ahold of though.

Skyscraper wrote:

When water isnt enough I use White Gas as I often find ISOpropanol too weak when it comes to dissolving tar.

Is that the fuel used in backpackers stoves? I recall purchasing "white gas" for my stove and should still have some. Do you recommend it for cleaning PCBs? I’m interested in finding a solvent for PCBs which does a good job at disolving oils but without needing to use physical contact and will not eat away at the PCB resin (like acetone will). I was also thinking of chlorinated brake cleaner might work well as I do not believe this contains acetone. It is cheap and flows out of the can with some force. Safe/cheap alternative to using contact cleaner, or just a bad idea?

I like PCBONEZ's idea of using Mean Green, but without using the dishwasher. If my wife found out, we would be buying a new dishwasher.

feipoa wrote:

Skyscraper wrote:

When water isnt enough I use White Gas as I often find ISOpropanol too weak when it comes to dissolving tar.

Is that the fuel used in backpackers stoves? I recall purchasing "white gas" for my stove and should still have some. Do you recommend it for cleaning PCBs? I’m interested in finding a solvent for PCBs which does a good job at disolving oils but without needing to use physical contact and will not eat away at the PCB resin (like acetone will). I was also thinking of chlorinated brake cleaner might work well as I do not believe this contains acetone. It is cheap and flows out of the can with some force. Safe/cheap alternative to using contact cleaner, or just a bad idea?

I like PCBONEZ's idea of using Mean Green, but without using the dishwasher. If my wife found out, we would be buying a new dishwasher.

This Heptane based White Gas is sold as a solvent for fat, oil and tar but it probably works perfectly as a fuel for portable stoves.

I think you can try your stove fuel as a solvent but I would still use a soft paper towel or sometimg to wipe the cards with, the difference is that you should not have to apply presssure. Before soaking whole cards in anything I would make sure it wont dissolve the plastic during the prolonged exposure. The Heptane seems to play nicely with plastic materials but I do not know what would happen if I for example soaked a whole motherboard over night.

feipoa wrote:

The results of my tests were not entirely inconclusive, however based on what I have read online, acetone is quite a bit better […]
Show full quote

The results of my tests were not entirely inconclusive, however based on what I have read online, acetone is quite a bit better at removing oils than Isopropyl. In my tests, neither IPA, nor acetone (by way of a nail polish remover bottle), would dissolve some petroleum-based grease in a dish. I used 99% IPA and my wife’s acetone-based nail polish remover. I’m not sure how the concentration of acetone in nail polish remover compares to lab grade acetone, but online suggests it can be 30-60%. Since the grease did not dissolve in IPA or acetone, my first thought was that if you simply soak your dirty parts in IPA and do not apply ample sheering force (from the squirt bottle) or apply physical contact to remove the grease, that the grease will remain on the surface after the IPA drys. Swishing the IPA around in the dish did not lift the grease from the surface.

The grease did appear IPA-phobic, that is, when I spread some bearing grease all over a glazed ceramic dish and stirred it with a stick, the grease would clump together into a single mass. However, even with the grease on a smooth surface, I had to use physical contact before the grease would lift from the surface of the dish. I am sure your results would vary depending on the type of grease (specific weight, constituents) and time/agitation.

I then proceeded to use some non-chlorinated brake cleaner. The grease dissolved pretty well in this case. An online search revealed that non-chlorinated brake cleaners often contains heptane and acetone. Perhaps the concentration of acetone in my wife’s nail polish remover was too low to be effective.

Since you generally do not want to use acetone on PCB’s (damage to plastics and resins), I thought I would try some other cleaners to see how they were at dissolving my sample grease. I tried some citric acid and acetic acid, but the result was the same as with the IPA. Mean Green did an ok job at dissolving the grease, but not nearly as good as the brake cleaner.

I used a few different test samples: a thin layer of bearing grease, a thick blob of bearing grease, vasoline, 3-in-one oil general purpose hinge oil, and sunflower oil. The best case was the thin layer of red bearing grease because I could visualise it in a white ceramic dish.

Further debate on IPA vs. acetone for cleaning oils, if you are interested. http://www.eng-tips.com/viewthread.cfm?qid=85538 This comment in particular, “I've used both for cleaning/degreasing and find acetone to be far better at actually dissolving and stripping "grease" than IPA. Non-polar, non-water soluble solvents like toluene etc. are better still.” I used toluene once, it worked well. I’m not sure how easy that is to get ahold of though.

Even within 'bearing grease' there are a lot of different kinds of grease.
Since the concern that inspired all this was compressor getting on PCBs wouldn't it be more pertinent if you did your tests with compressor oil rather than grease.?
Compressor oil is basically motor oil. (Crank case oil.) Much different than most greases.
It gets to the PCB by getting past worn rings into the cylinders.

feipoa wrote:

I like PCBONEZ's idea of using Mean Green, but without using the dishwasher. If my wife found out, we would be buying a new dishwasher.

You mean the procedure I spelled out in the first page of the thread? Re: This is a bad idea right?
I don't use a dishwasher. I was merely saying I've experimented with it and it's a workable solution.
If I had a much bigger shop I might install a dishwasher out there just to keep my work out of the kitchen.

So actual Mean Green is available in Canada? - I've never been sure if it was even available it is outside the US.
Not confusing it with Simple Green, right? Simple Green is much weaker than Mean Green.
.

gdjacobs wrote:

PCBONEZ wrote:

It's not rubber you need to worry about it's plastics. The resins use various solvents and if you dunno what they all are then u […]
Show full quote

It's not rubber you need to worry about it's plastics.
The resins use various solvents and if you dunno what they all are then using things like ether, heptane or naptha can be risky.
Might work just fine on a bunch then you get one and it's ruined because some different plastic was used.
.

I was thinking of heat shrink and the bottom seal on electrolytics, but you're right. Even sockets and IC packages could potentially be damaged.

I still think the only sure way to check is to test, probably do repeat exposures until there's evidence of component failure. Ideally on an unstable circuit design.

You're right too.
Silly me, forgetting about the capacitor bungs...

I did my fair share of experimenting with the nasty volatile chemicals way back in the 90's and given that up until the mid 90's I was big into building hot-rods and restoring cars I had quite a selection to chose from.

Ultimately after a few bad experiences I decided to stay away from the nasty volatile chemicals.
It's been so long ago I don't remember specifics as to what I was using but I do remember some of the unexpected bad results.
In both cases below some chemical worked great for a few boards then out of no where screwed one up.
- In one case the entire PCB softened on the surface. It became tacky like there was wet glue all over it. It still worked but I was afraid to use it as all the dust bunnies would get stuck to it and I'd end up with motherboard shaped hairball. I set it aside on a shelf hoping it would firm back up but after a few weeks it was still tacky. It got boxed and stored and forgotten about. I came across it unpacking after a move 2 or 3 years later and it was STILL too tacky to use.
- In this one the IC chips were affected. All the writing came off. They went from their normal appearance to a dull dark whitish-grey (looked like they had been sanded) and there were crazed cracks all over their surfaces. It still worked but there was no way I could sell it for full value.

That happened at a time when I had arrangements with local computer shops that gave me on average 1 to 2 dozen motherboards a month for free.
(They were returns. Testing (by the shop) and RMA cost more than replacing them outright. I shared proceeds from those found good and sold with the shop.)
When you are getting the product for free a few screw-ups don't matter much.
I'm not getting free motherboards anymore so screw-ups hurt and I stay away from the nasty volatile chemicals.
.