Removing epoxy resin from a PCB

: I've got a B&D stapler which has died. The solenoid is ok, so it's likely :a fault on the PCB. Which is potted in what looks like epoxy resin on the :component side. : : I'd normally just buy a new one - but have trillions of staples for it :bought off Ebay.;-) : : I can get a new PCB for approx 60 gbp - but that's more than the thing :cost new. : : Any ideas about removing the potting compound hopefully without damaging :the identification on the components? I've likely got everything on that :board 'in stock' so would be happy to replace the lot. But don't have a :schematic.

I would forget about trying to dissolve the epoxy. While this can be achieved the chemicals required will cost as much as the new pcb and they will attack the components as well as the epoxy. Many years ago I tried it with an epoxy potted ignition system from a Johnson outboard motor and it took weeks to dissolve the epoxy and all the component colour codes were taken off as well. Some components also had their epoxy/plastic coatings removed as well. Surely you can still buy a stapler which will use the staples you have in stock?

I did find once on an epoxy covered VCR daughter board that the epoxy may have lifted some IC pins via differential thermal expansion or something. Externally forced the package back with cable ties , wedges and rubber IIRC. Didn't attempt trying to remove the epoxy. Did once manage to excavate with a Dremmel and fine grinder but forget what that was over, probably not labelled ICs. If you're lucky they will have diluted the epoxy with carbonate filler so not so hard going

-- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on

"Dave Plowman (News)" wrote in news: snipped-for-privacy@davenoise.co.uk:

We used to boil epoxy coated capacitors in DMF (di methyl formamide) [nasty stuff! Avoid contact, breathing etc.] It WILL take off the epoxy but it will also corrode metals.

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bz    	73 de N5BZ k

please pardon my infinite ignorance, the set-of-things-I-do-not-know is an
infinite set.

bz+ser@ch100-5.chem.lsu.edu   remove ch100-5 to avoid spam trap

This may sound stupid, but a place I used to work tried coke (the fizzy drink) and it seemed to work somewhat, god knows what it does to your insides !

HTH.

I will give that a try. Do you warm up the liquid ? keep it all at an elevated temperature for hours ? scrape with a blade after soaking? prize under with a blade?

-- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on

I just tried a number of household chemicals in test cells with flakes of 2 week old cured epoxy, over a couple of hours, all at room temperature. The test piece in coca cola is still hard. The only ones showing promise are acetone as nail varnish remover and 2 types of paint stripper paste Polycell with Dichloromethane and methanol and an "151" containing Methelene Chloride and methanol, probably the same activce chemicals. Acetone and paint stripper mixture look most promising producing a gooey mess and reduced soft test piece in less than an hour. All with no mechanical action at all.

For pcb use I would recommend repeated sequence, motorised wire brush then this mixture on the track side. On the component side Dremmel and very small ballmill or burr to grind around obvious faces to iCs, large caps, and transistors so you could prize off the section of epoxy over any markings, then mixture of Dremmel or brush and epoxy softener. Sustained elevated temperature may help the chemical process.

-- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on

Unless you are very careful, your epoxy solvent will destroy your PCB also.

Al

Use a heat gun set to a temperature below the melting point of solder. Epoxy gets much softer and weaker as it heats up. At the right temperature, it will scrape off like putty. Andy Cuffe

snipped-for-privacy@gmail.com

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I tried mix of paint stripper about 1 : to nail varnish remover about 5: coke cola about 5 and my test bit of epoxy disappeared to gloop in about 3 hours, the stripper + acetone test epoxy one is still substantially there - weird

I haven't tried it, but I know someone who supposedly used a propane torch to soften up the Epoxy and then scraped it off. This was a potted laser power supply brick and the resulting PCB looks like new.

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likely

But the solder is still connected to active components and now surrounded in a large thermal mass, not the quick jab and scarper of the soldering operation

For a populated board , how high a temp would you allow the epoxy and hence thermal mass of enclosed active componentry to get up to? I think I would bury a diode in there and monitor the forward voltage for temp guide. I'de be happy with 70 degree C and probably 100 deg C , but how much higher ?

-- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on

在 2009年4月28日星期二 UTC+8 06:52:05，<Dave Plowman (News)> 写道：

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