Denso EFI potting=ack!

[Tom Cloud]

>> Has anyone encountered this horrible stuff and if so, is there any safe 
>> solvent for it that won't harm the board?
>
>I used to work for a defense contractor.  Everything was conformal coated
>or potted.  We had a refrigerated freon tank to dissolve the coatings.
>Hang it in the vapor for a while, and it would drop off.  Drop it in the
>liquid for a few seconds, and it's gone.  I don't recall which refrigerant
>was used, but if you can get your hands on some, try spraying the board.
>I think some "cool-it" type sprays are still available with freon.
>If it's an epoxy type material, all you can do is chip away at it.

freons are like philodendrons ... there are hundreds of them.
the freon you probably used was liquid at STP, and the contraption
you describe is called a "vapor degreaser".  I've used them with
various solvents: freon & tri-chloroethylene included.  The
principle is the liquid is heated with a heater (what else ??),
the vapor rises and is condensed by a cooled air blanket near the
top of the vat, the top part of which is surrounded by cooling
coils -- usually cooled with tap water.  The vapor doesn't escape
into the surrounding area, and any part that is put into the vat,
and which is cooler than the vapor, causes the vapor to condense
onto it and become liquid.  Makes a great carburetor cleaner,
though not as good as an ultrasonic cleaner.


Tom Cloud <cloud at peaches.ph.utexas.edu>