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OT: Potting compounds

I need to pot some electronics and know nothing about potting. I've looked over several web site of companies that provide potting compounds and seen many different types of compounds.

The electronics I'm designing will be going into a engine compartment in a truck. The potting compound will be used to keep water, dirt, and grime off the electronics. The electronics is relatively low power and does not generate much heat. The engine compartment on the other hand does get rather hot.

Does any one know of a good potting compound that can be used in a application like this? I'd like to have some stuff that did not require high temp's to cure, mixing, and was relatively cheap.

Can you folks out there recommend any compounds and vendors?

Thanks...

--
Greg Deuerling
Fermi National Accelerator Laboratory
P.O.Box 500 MS368  Batavia, IL 60510
(630)840-4629     FAX  (630)840-5406
Electronic Systems Engineering Group
Work: egads_AT_fnal.gov, remove '_AT_'
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Egads
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I would use RTV 154 from Dow Corning, or the GE Silicones equivalent. However it is not cheap, requires weighing out to mix and curing in an oven. You might try one of the polyurethane foam products sold in the spray can at Home Depot type stores. The only drawback with it is once you start using it from the can you need to use the entire can as the nozzle plugs off so it can't be reused. Once potted in the polyurethane it pretty well becomes throw away if you need to get back into it. Good Luck Jim Stockton

Reply to
Jim Stockton

Reply to
Jim Stockton

If you're doing this for production/sale, I'd get in touch with 3m or GE reps.

If it's a one-off and non-mission critical, I've had good luck with Tap Plastics Clear-Lite casting resin. It's relatively cheap, behaves the way the package says it should and has a nice clear appearance. The only downside is an awful odor during the curing process.

Reply to
Jim Stewart

I'm potting some electronics in a resilient outer shell which will live outside in all weather, be stepped on and dropped, etc. I first tried Polytek's Poly 81 line, a 90 duro polyurethane, and it really isn't suitable. It flows too slowly when mixed, and you have to leave it under vacuum for more than half the pot life to get most of the bubbles out, so that gives you even less time to get it into the mold. And even then you'll probably get bubbles during pouring, which won't rise because the viscosity is too high. Finally it just isn't tough enough because of low strength.

I'm going to try Smooth-On's ClearFlex next, which is *much* lower viscosity.

You don't need much of a vacuum setup. I soldered a hose barb into the lid of a pasta jar, and looked it up to the inlet of a fridge compressor using vinyl tubing. Mix in the jar, vacuum, then chuck away the jar (we use lots :-) when you're done.

Measuring and mixing is important. Get a proper stirrer for your electric drill, a good balance or scale, and plenty of cheap mixing cups.

Clifford Heath.

Reply to
Clifford Heath

"Clifford Heath" wrote

An embedded paving stone?

Reply to
Mike Turco

No, an orienteering scoring control. MSP430 with IButton interface.

Reply to
Clifford Heath

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