(OT) Electronics injection moldable material

I'm looking for a light injection moldable (or pourable) material that has these properties.

1) dielectric and non shielding to RF signals

2) non corrosive to electrical components (electronics can be conformal coated if this can't be met)

3) Floats on water when cured (light weight)

4) curing process does not damage SMT electrical components (not extreme high temperatures etc.)

thanks

A few more requirements to narrow it down.

5) It should be rubbery and not rigid since it will be handled a lot and should not be dented when it is slightly pinched or bumped into metal sharp objects

6) should not soak up water

7) should not melt or get gooey when exposed to gasoline, oil or alcohol.

did I mention it still has to float? :)

thanks

I looked at the polyurethane foam and while it meet my original posted requirements I don't think it will be rugged enough for continuous handling and bumps and dings.

This guy will be velcroed to a vibrating and buzzing R/C boat (hence the fuel and oil exposure) and may fly off and land in the water from time to time (must float, and not soak in water).

The handling is folks dropping it on the cement launch pad, tossing it in their field box with pliers, screwdrivers, etc bumping/rubbing against it.

I'm thinking something more like an RTV with microbaloons in it. or similar.

I've previously explored a similar project, and you're headed down the right path using a soft material. A hard casting material will break the solder joints during thermal cycling.

You'll find loads of educational info at this site about resins, Shore hardness (one scale for solids, one for pliables), casting, and other accessories. They sell a wide range of types and colors, and you can get small sample kits; however, they have zero info on their electrical properties, so you'd need to test for yourself.

These guys are targeted at the electronics space:

I also found a couple Yahoo forums on casting that were good for general tips (degassing, etc.)

Including gasoline tolerance?

Good luck, Richard

I read in sci.electronics.design that Mook Johnson wrote (in ) about '(OT) Electronics injection moldable material', on Sat, 16 Apr 2005:

Shrink wrap it over the PE foam. You could drop it from the Moon and it would bounce.(;-)

--
Regards, John Woodgate, OOO - Own Opinions Only.
There are two sides to every question, except
\'What is a Moebius strip?\'
http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk

thanks for the reply.

I didn't list gasoline in the original post which is why I supplemented it with this one.

the poly foam with adhesive lined Polyolefin heat shrink tubing is an interesting option. Doesn't look professional though.....hmmmm

good for prototypes though.

RTV sucks up solvents like a sponge. Epoxy with microballons? Exotherm might be problem in a large mass.