Potting resin for engine compartment electronics

[ChrisBennet]

I'm looking to encapsulate some electronics so it will survive in the engine compartment of a 911. Epic Resins has something that would work but their minimum order is $150 and I only need a few ounces. Does anyone know of a less expensive source for harsh environment potting material?
thanks,
Chris

[snowman]

Try Emmerson Cummings http://www.emersoncuming.com/YourSolution/index.jsp?id=1&c=0

I would try http://www.emersoncuming.com/YourSolution/ProductDetails.jsp?i=5

another choice would be
http://www.emersoncuming.com/YourSolution/ProductDetails.jsp?i=78&s=c

encapsulants. Also see products called encapsulants that look like sand. You pour it in or on whatever, heat it up to say 125 deg C and let it harden. Used for military applications, High G, etc. ask for a SAMPLE.

At one time they sent samples free, sometimes they charged about $50.

Tell them you have an automotive application, temp range -55C to plus 125C, lot of vibration, oil, gas contanimation. Need to protect electronics (whatever type) from this environment. Thermal conductivity is not an issue unless there is high power devices that are not mounted to a heat sink or metal part.

Put your electronics in this stuff and you can shoot them out of a cannon and they will still work and I know this for a fact.

[ChrisBennet]

Thanks Jack!
-Chris

[HarryD]

Chris,

Try WWW.mcmaster.com page 3169.

Epoxy for Potting and Encapsulating
Low viscosity and thermal expansion as well as a good heat conductor. This two-part epoxy is ideal for electronic casting and encasing an item in adhesive. It's thin to provide good flow and help eliminate trapped air. Heat conductivity draws heat away from the part. Also resistant to weather, water, vapors, petroleum lubricants, and mild acids and alkalies. Color is black.
Thermal conductivity: 10 Btu-in./ft.2 -hr.° F. Ability to withstand electrical voltage without rupture: 520 volts/mil. Temp. range is -40° to +212° F. Begins to harden in 15 minutes. Reaches full strength in 6-8 hrs. Mix ratio is 2:1.
To dispense the 50-ml cartridge, use the adhesive gun (sold separately). Attach a mixer nozzle (also sold separately) to the gun to mix as you dispense. Full package quantity is 12.

[ChrisBennet]

That's great Harry! I've ordered from them before. I know they have "everything" but it didn't occur to me that they'd have that.
thanks,
Chris

[snowman]

Some additional info on electronics encapsulants.

Older electronics and relatively large things like coils and transformers were relative immune to shear by the encapsulant. As electronics became smaller, as most modern electronics are, they are more and more subject to this problem. Even the newest and greatest encapsulants, such as the Emmerson and Cummings ones still have some problems, but many order of magnitudes lower than old ones like the black coil potting epoxy cited above. If your parts are relative large, like coils and have relative large wire, like 22 awg or larger, there may not be any problems, but for the surface mounted, parts with very small wires, circuit boards with a lot of parts on them, stick to the lowest density stuff you can live with. The more modern epoxy also work over -67degF to over 300deg f, much better than the old stuff, not to mention far better chemical resistance. Some of the newer stuff is also cheeper. Also using single part temp curred epoxy elliminates mixing ang guarentees proper results, only downside is having to store in the frig.

[ChrisBennet]

The epoxy's I found are more expensive than the electronics I'm trying to protect.
-Chris

[snowman]

Could be quite true, that the cost of the encapsulant is high, but it allows the electronics to live where otherwise it could not. As to one of a kind, I think you can get a free sample, for any kind of real production the cost isn't really that bad. There are some much lower cost epoxys out there but they break more than they protect. Its low cost enough that all the auto mfgs use some kind of it in all their new electronic stuff for autos. I beleive that for sensors and devices in severe service like map sensors, O2 sensors, g sensors for airbags and the like many are using an Emmerson Cummings product on one kind or another. Computers or car "brains" make extensive use of Emmerson cummings conformal coatings.