Re: Silicon oil leakage on PCB - how to remove?



John Woodgate wrote:


You can't wipe the stuff off because of its surface tension and viscosity. You may be able to get a 'removing fluid' from the oil suppliers. It may be costly.

I am assuming that the problem oil is something like a polydimethylsiloxane
( http://www.chemexper.com/chemicals/supplier/cas/63148-62-9.html )

I would worry that the KOH / Methanol will "clean" the polymers off of the pcb silkscreen, chips, and even the PCB substrate. I have seen 250 mL beakers that I used as a KOH/Methanol bath display significant etching. It dissolves skin. Use gloves. It dissolves corneas faster. Use goggles. Spatter is invisible on clothing, and transfers to unprotected skin. Change clothes and shower after handling. NaOH/Methanol forms insoluable crud, so KOH is preferred.

A couple of web sites mention benzene. You can't (or shouldn't) get that now, but toluene or xylene may substitute. I'm a little surprised that they work, and don't remember trying them directly. I suspect that you can get mixed xylenes at an art supply house as some or other paint thinner or brush cleaner. They burn easily -- act as if you are handling gasoline.

Someone else mentioned diethyl ether. The flammability of (this) ether makes gasoline look safe. More problematic is that you will be tempted to keep the left over material. On exposure to oxygen, even in a "closed" container, it forms explosive material with LEGENDARY sensitivity.

Another web site did not offer any information specifically relevant to this newsgroup at all: http://www.indecentblogging.com/blog.php?id=5906

Despite the general acceptance of opinion over lab work in most newsgroups, I do mention the entry from the paper mill. Use your browser to search for "Table 1" about a third of the way down the article. My gut sense was ethyl acetate would be a good solvent, and their finding of methyl ethyl ketone fits in nicely with that. Their finding of hexane surprises me some, but hey, they went to the lab and I didn't.

http://tappsa.co.za/archive2/APPW_2004/Title2004/Determination_of_silicone_defo/determination_of_silicone_defo.html

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