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It sure looks like a polyurethane glue.
Been my suspicion as well. I've attacked it in the past with files, knives, and sandpaper. Real pain in the ass. Came across a board few months back covered in this stuff with hot melt completely covering it
Took me forever to clean the damn thing up. I did find this:
http://crosslinktech.com/support/tips-and-tricks/how-to-remove-cured-epoxy-or-polyurethane.html
and this sounds promising:
http://www.dynaloy.com/products/urethane
For now I'll be sticking with the cutting/scraping method, but hope somebody finds something better that doesn't cost $200+ a bottle
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I've no problem with being wrong, I have been most of my life about something or other. What I have a problem with is someone who (and I've seen this repeatedly done to others) just flies past saying "you're wrong" without contributing anything to move the conversation towards its goal or any evidence that excluded my suggestion - just a bald, pointless, unhelpful "It's not...". That's just unhelpful and I said so. Is that so wrong? And once it has clear that someone just wanted an argument, he got added to my ignore list and, well, I ignored him.
This is my final word on the topic. Be the big man and make it yours too.
Reading the thread, it appears you need to relax. I didn't see anything rude of condescending or argumentative whatsoever in his first post. He just said "no, it's not"... he did offer additional information - he said it won't soften with heat. The only offense was what you read into it and chose to challenge him on and claim he was looking for an argument. You also made sure to tell him you were putting him on ignore - making sure to get the last word in without giving him a chance to reply. That's rude and argumentative in my book.
Anyway, Bravo... did you have any luck getting that stuff off? I have found IPA works, but only if you soak it for a looooong time, like days. Acetone works, but will absolutely damage plastic parts because it also needs to be soaked for some time. It will also damage PCB's due to the length of soaking time required. Something in the middle might work... maybe flux cleaner. I like the freeze spray idea. -
That looks like the same stuff I first saw in electronic products over 30 years ago. High temperature causes it to turn brown. It also becomes corrosive and conductive. It is responsible for causing many premature faults.
That's my experience too. My whole life I've loathed this stuff and wondered why manufacturers keep using it. Deliberate planned obsolescence electronics-poison maybe? I posted something a few months ago about some WiFi nodes I'd been given that were dead due to this vile stuff and its corrosive-conductive effects.
It's something solvent based, judging by the way it shrinks surface-first. You can see that effect in the final pic, where a bit looks like it has tendons.
Definitely not hot-melt, which doesn't shrink as it cools.
Sometimes you can cut/peel it off by gripping with the jaws of fine wirecutters. But it's very tenacious.
With age and heat it goes darker brown, becomes very corrosive, and I think a little conductive.
Whether it's rubber or urethane based, no idea. -
Hi this type of adhesive is very similar to "contact cement" , basically a synthetic rubbery type compound.
Also similar to "no more nails" and similar construction adhesive.
Polyurethane doesn't shrink or make the stringy bits seen in the photo.
Xylene or Toluene are the original solvents, and while these will soften & dissolve the adhesive, it will just turn into a sticky mess (like chewing gum).
These solvents are OK on the hard plastics used in electronic assemblys, but will make PVC swell, and possibly go brittle later.
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It is neoprene based glue, used because it is elastic, sticks like crazy, and cheap as dirt... It is applied with a brush, cheap and easy..
It is very good to vibration proof (because of elasticity, basically you rubberize things)..
It is a pain to remove. There are solvents, but very aggressive (and toxic) to everything else ..
Cooling(freezing) and breaking of pieces and cut with scalpel works best for me.. And lots of patience...
Sometimes connectors or other stuff will be easier to replace than to clean ..
It used to be used a lot on far East consumers electronics 20-30 years ago, not so much any more luckily... -
Freeze it with freezer spray, then it becomes brittle and breaks off easily. Solvents tend to make it soft yes, but it then spreads all over the place. Freeze and it just breaks off with slight movement or prodding.
upside-down canned air would work too -
Updates ....
I decided not to use any solvent, as this glue is so sticky, worry it will soften too much, and part of it got dissolved more in the solvent, turning into lower viscosity liquid that might sip in under the connector's pins, or spread and run under the surrounding smd components, and worst created a soft new sticky layer of this nasty glue covering the board area.
Also possibly it will turn into corrosive substance as others pointed out at later date, definitely a no no.
Thanks to SeanB on the idea of freezing the glue
, yes, it works, but not perfect though. It still needs quite some elbow grease, but the work is significantly easier than before.
The reason is, once the glue is freezed, the picking/yanking/scraping process will be a lot easier, as bigger sized chunks just came off rather than small pieces by pieces which is really painful task to do.
I will just let the photos to tell the story ...
Here a TO-220 chip as size reference, just watch closely the small pieces that I put on the IC's pin, those are the pieces that chipped off when its at room temperature.
I used this technique as I think its effective, 1st, use a sharp needle point to tear down or penetrate the glue, beware of PCB traces or any other weak surface if any below the glue. Once penetrated and torn, use a sharp tweezer to pull or sort of yank it off thru the glue opening.
The push pin needle, and the sharp tweezers are the tool I need to get the job done. The serrated tweezers will make it bite & grip the glue stronger, and wont slip off easily compared to non serrated one. Again, TO-220 as size reference for you to imagine the size I was working on.
An improvisation, as I don't have freezer spray, I used the butane cartridge from the portable stove, and the nozzle from my shaving cream.
LOL ... It freezed out the glue effectively on a really short burst. (yes, I tried it at other part 1st) Don't worry, did it at my back yard windy garden with open sky.
Warning to other readers, using the butane gas this way, is very-very dangerous as its highly inflammable, and I am not responsible for any accidents that may harm or kill you or burn down your house. And remember, if you're going to use this method, make sure you do it out door in a well ventilated place.
Hope this will be useful to others someday.
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Warning to other readers, using the butane gas this way, is very-very dangerous as its highly inflammable, and I am not responsible for any accidents that may harm or kill you or burn down your house. And remember, if you're going to use this method, make sure you do it out door in a well ventilated place.
Hope this will be useful to others someday.
This time of year for a great many users of this forum the solution is simple. Just go outside. No need for repeated freezing, it stays cold.
For a great many others the answer is to wait 6 months before working on this board.
For those living in the middle, you have my sympathies. -
Even those in the middle lands have freezers they can put a small board in for a while.
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More on the propane freezing approach.
The wart freezing kits at pharmacies just use propane/butane, with an extension tube about 1.5mm ID, and a piece of foam stuck on the end.
These are a bit expensive to buy for freezing glue, but you can make the same apparatus yourself, the piece of foam on the end is the secret, it stops all the liquid going everywhere, and by evaporating off at the foam, and "auto refrigerating" it creates a reservoir of cold liquid in the foam you can just drip off /dab onto the offendingwartglue.
http://dermaltherapy.com.au/products/foot-care/warteze.
The actual amount of flammable gas produced with a bit of foam on the end is low enough to be used safely indoors.
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Warning to other readers, using the butane gas this way, is very-very dangerous as its highly
there corrected for you. it can be spotted easily by anybody here, just in case for any kids out there who have little clue what butane gas is... and this is safety life threatening issue so i think its necessary to make a simple typo check. btw another suggestion as freeze agent is the co contact cleaner... its just as flammable, but more specific to electronic use... and i believe its more freezing than butane liquid, ymmv..inflammableflammable...
and lastly, i can certainly confirmed the yellowish goo is not simply a household holtmelt glue. i usually just scrap them off bit by bit with sharp tip knife or tweezer if i have to.
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there corrected for you. it can be spotted easily by anybody here, just in case for any kids out there who have little clue what butane gas is... and this is safety life threatening issue so i think its necessary to make a simple typo check.
"inflammable" is the correct term. It does not come from adding "in" to "flammable", but rather from the Latin inflammo, inflammare, inflammavi, inflammatus sum which means to ignite. -
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"inflammable" is the correct term. It does not come from adding "in" to "flammable", but rather from the Latin inflammo, inflammare, inflammavi, inflammatus sum which means to ignite.
Awesome info. I think I always assumed it was just a quirk of English. The same way "shelled peanuts" are the ones that have been shelled (here we go again; "shelled" meaning the shell having been removed).
OP, I would have thought an Exacto, or similar, would have been helpful, too. Along with the freezing and pin and ridge-tooth tweezers. Great job on the writeup. Good to know. -
On a similar vein I have been removing hard drive magnets from the pole pieces. So far only one was not stuck down, so the whole lot has been sitting for a week in a bottle of MEK solvent. This does dissolve the locking adhesive after a while, though it is fatal to the little pieces of plastic that were on there as head lifters and such, they turned into powder after swelling up. Got about 10 magnets off now, still have around 20 to soak through.
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there corrected for you. it can be spotted easily by anybody here, just in case for any kids out there who have little clue what butane gas is... and this is safety life threatening issue so i think its necessary to make a simple typo check.
"inflammable" is the correct term. It does not come from adding "in" to "flammable", but rather from the Latin inflammo, inflammare, inflammavi, inflammatus sum which means to ignite.
Both flammable and inflammable are in the dictionary. They both mean the same thing, "easily set on fire". -
btw another suggestion as freeze agent is the co contact cleaner... its just as flammable, but more specific to electronic use... and i believe its more freezing than butane liquid, ymmv..
Interesting suggestion, just fyi, I own that "exact" contact cleaner as you pointed out above, my finding is when it comes to freezing capabilty, the butane liquid when evaporates, beats my contact cleaner liquid out of the water. In my test, its simply no contest, butane liquid win.
For example, just two or three short burst of butane liquid at the pcb, the other side of the pcb starting to form and grow "freezed" ice flakes, so not just condensation, really white ice flakes.
Here is my contact cleaner vs the butane cartridge vs my shaving cream.
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Butane evaporates at about -1C. isobutane evaporates at about -10C and Propane evaporates at about -40C.
I use Propane for shrinking mechanical parts for an interference fit and butane or isobutane for freezing depending on what I have around.
A serious blast of liquid propane from an up-turned 9kg BBQ cylinder has serious cooling potential though, although the mercaptan *stinks*.
I have some kit that removes the mercaptan but the resulting product is time and equipment intensive. -
Butane evaporates at about -1C. isobutane evaporates at about -10C and Propane evaporates at about -40C.
Hmm ... propane .. now I know which friend to visit if I need instant freezing at small spot.
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The yellow glue that plagues repair techs and hobbyists is chloroprene (neoprene) adhesive. Google 'remove yellow glue pcb' for links to discussions. Two from sci.electronics repair:
https://groups.google.com/forum/#!topic/sci.electronics.repair/0M6NpItdfSM
https://groups.google.com/forum/#!topic/sci.electronics.repair/nYve09tYKwY
(The second thread has some useful information before it descends into name-calling...)
Summary: some contact cleaners (Servisol 160, RS 180-847) soften the glue enough to make removal possible (though still tedious). The active agent is probably cyclohexane. This chemical compatibility chart indicates that chloroprene has poor resistance to cyclohexane:
http://www.usascientific.com/pdflit/Chloroprene%20Resistance%20Chart.pdf
About a year ago, I worked at removing this glue from a broken Roku Soundbridge switching supply. The toastier areas had resistance in the megohm range (though I don't know whether any high-impedance circuits were affected; it ended up needing a small electrolytic replaced). After doing the research above, I got some naptha (white gas / camp fuel) which contains about 15% cyclohexane. It worked better than IPA or methanol, but it still took me a few hours to get the glue off. Next time I'll try freezing it, or find a solvent with a higher concentration of cyclohexane.
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R600 has no smell, and is a very pure propane. Your fridge likely has 18g of it in the refrigeration circuit.
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R600 has no smell, and is a very pure propane. Your fridge likely has 18g of it in the refrigeration circuit.
R600 is plain old butane. R600a is iso-butane. R290 is propane.
Fridges run on R600a, and it's a crapshoot as to whether you get gas with or without the stench. Mercaptan is not particularly friendly for refrigeration systems (although it is in minute quantities and doesn't really hurt anything), but there are odorants out there that will supposedly maintain the smell over time. Some companies do, some don't.
Mercaptan is broken down over time by stuff normally found in refrigeration circuits, so often after a year or so the gas generally loses all its smell anyway.
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Old thread, but there's an old remedy: GC Electronics RADIO TV CEMENT SOLVENT:
https://www.alliedelec.com/gc-electronics-10-312/70159779/