On 03/03/2017 05:11 PM, N_Cook wrote:
On 03/03/2017 21:05, wrote:
On Friday, March 3, 2017 at 3:51:17 PM UTC-5, John Robertson wrote:

Thanks, we've had many an Eprom with corroded legs that are from the
70s, in some cases the legs break off inside the IC sockets when the
EPROM is removed. Also this is common on some other ICs used in the
early 80s, such as Galaga which has Namco custom ICs, where again the
legs are corroding right off them.

Is there any way to arrest the process? Be nice to have something to dip
the legs into to cancel the corrosion, similar to using white vinegar
and water (50/50) to neutralize alkaline battery leakage corrosion.

John :-#)#


The best way I have found - if at all possible - is a coat of flexible
lacquer over the entirety. I admit to having a bottle of flexible
fingernail polish hidden away amongst my other solvents for this sort
of thing. Stop the air, stop the corrosion.

Peter Wieck
Melrose Park, PA


I've quite often found problems with conformal coating, over decades, it
seems to trap moisture underneath as though hygroscopic/delequescent or
whatever its called , an oily/ jelly type composition beneath, complete
with green copper carbonate corrossion product

Parylene is about the most impervious common coating, but any plastic
has orders of magnitude higher gas diffusion rates than any metal. In a
humid environment, water will penetrate until the net flux is zero, so
if you have nasty hygroscopic corrosive crud underneath, your board is
still doomed.

Cheers

Phil Hobbs


--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510

hobbs at electrooptical dot net
http://electrooptical.net