Would it be crazy to attempt potting with GE Silicone II black caulk?

I know this will technically work, but will it eat my traces over time?



*(GE Silicone Window and Door Caulk, black)

I've read that this is safe for electronics. But you know, people say all kinds of crazy sh*t on the internet. So I figured I"d come to this other crazy corner of the internet and ask...

The purpose is to add weight to a DIY light pen, and also to adhere the PCB to the plastic pen body. I have 2 "paying" (not much) customers and I'd like to deliver something that will last. I figured I'd spray the boards with conformal coating first. Adequate protection, that is, if any is really needed?



For reference, here's what I'm potting. DIY Vectrex light pen, except in a black marker body.

Don't know

Fry's sells silicone in the electronics aisle

I'm also under that presumption that you shouldnt use it hence acetic acid in it.( ie.acid cure silicone)dont know if some coating would help?
I would probably buy some expensive speciality silicone

I'm sure you've already figured this out, but I thought I'd add some notes.

You are looking for a property called "deep set" RTV.  Most of the stuff you find won't cure very deep.  They make a special 2 part RTV to cure as a potting compound.  See a note by Dymax

I'd suggest a two part urethane instead.  It will be softer than epoxy, but still cures well.  Mix by weight (get a scale) and de-gas if you can get  a vacuum chamber. 

(I know this is an old thread but it's still relevant - folks are still making Vectrex light pens.  Myself included)

Since you explicitly mentioned Silicone II then you don't have to worry about acetic acid - that's Silicone I.  *However* I think Silicone I would be perfect for this job (and I'll likely try it myself when I have all the parts to make a Vectrex pen) if you mix the Silicone I with corn starch, which causes it to set rapidly (about 10 minutes max) into rubber.  (If you know the Instructables site, search there for "Oogoo" for more info on this polymerisation trick)

How did your lightpen turn out, and how well has your potting lasted?  What did you use in the end?

Thanks Graham for reminding me about this, and for the helpful suggestions.  I'll check instructibles for Oogoo. And thanks to everyone else who provided input earlier.

The light pens turned out fantastically. For these prototypes for friends, I just used hot glue to keep everything together, and that worked just fine.

I accumulated the parts to build a bunch more but never got around to it. Let me know if you're looking for parts. xefned on the vector gaming forums.

Also, Kontakt Chemie has the "Plastik 70" product, which is an anti corrosive coating for PCB's. You could hit it with this first, and then use whatever to seal the pen in it's housing.

I've used hotglue and for water-proofing liquid perspex.

Hotglue is cheap and fast. Liquid perspex needs more care and is a lot more expensive. But hotglue isn't really waterproof.