Coating a Motherboard In Thermal Resin?

Bat Country writes "I've had an idea in the back of my head for some time (and I'm surely not the only one) that it would be a worthwhile project to coat a motherboard in thermally conductive electrically insulating resin — complete with all of its various components — for the purpose of immersion, shock resistance, whatever. I'm curious to find out if anyone's undertaken a similar project or if it's known to be a shockingly bad idea (due to shrinkage during the curing process) already. Thoughts?" If you've done anything similar (even an experiment that failed), how did you go about it?

Comments

SUN used to do it.

[UseTheSource]

When they offered the SUN Crypto Accelerator cards for offloading SSL computations, almost the entire PCI card was coated in resin to prevent tampering. I don't think they're still available for purchase from SUN but I'm sure we've still got a few in storage at work somewhere.

Re:SUN used to do it.

[Asmor]

I saw a documentary on card cheating devices, and one of the early card-counting computers was dipped in something to prevent people from backwards engineering it. It included a failsafe, as well, a thin filament wire designed to be pulled off if the stuff protecting the computer was scraped away, and without that wire in place it would malfunction.

Re:SUN used to do it.

[noidentity]

Someone guy unpotted a Votrax module and refurbished the damaged components so that it still worked afterwards and he could reverse-engineer it. It's interesting and has lots of pictures of before and after. The thing starts out as a a big block of epoxy and ends up a normal-looking circuit board.

You should see the IBM version

[sirwired]

The IBM crypto processors had the module containing the key wrapped in wires (which, if broken, or changed in length, would erase the key) and internal to the module were thermal and x-ray sensors to prevent sniffing the contents of the module that way.

SirWired

It's common on high-tech boards

[Anonymous Coward]

My degree is Materials engineering, and I remember an undergrad design course where one of the groups was working with Rockwell Collins on this exact project.

They already commonly coat their boards in stuff for the very reasons you've listed. All kinds of circuit boards for radios, radar, anything electronic inside a jet fighter. The project was to find less-toxic alternatives that could match performance and cost.

cockroaches

[doug]

Years ago I worked at a company which had had problems with some telecom equipment in the field and no one could ever find any smoking gun. Random problems pointed to several different places on one particular board. One technician must have been working late, because apparently the CO filled with cockroaches once the sun went down. One of the theories was that bugs crawling across the board caused random short circuits. The customer was getting pissed, so management opted for a shotgun approach. Half a dozen shot-in-the-dark fixes were made, including adding an insulating coating. No one knows which one (or combination) of the fixes did the trick, but the random outages went away. That was engineering at its finest.

Re:Conformal Coating

[DeusExMach]

Same industry, and yeah, you're right. Also: with conformal coating you CAN NOT get that stuff on the contacts if you want the components to work correctly. And if you're not sealing up your connection points, you're still going to get a short if you use a non-electrically neutral fluid (like water) to cool your system. You CAN use CC if that really floats your boat, but considering the cost way outweighs the benefit on personal electronics equipment, I don't know why you'd want to...

Yes it works

[John Sokol]

When I was doing a start up called Nisvara 2002 (now dead) we were building Silent computers and server rooms that didn't require air conditioning. Something like 50% power savings!

I was able to Pot or coat, power supply's, hard drive and motherboards in various materials.

The key is thermal conductivity. Yes some one here mention diamond, but that is expensive in unrealistic although diamond dust power was available from GE at a much lower cost then I expected. Carbon Fiber and other carbons are great except they are electrically conductive so they are ruled out (except diamond that is).

What worked great was epoxy with silicon carbide which is dirt cheap and sold as sand basting powder. Also boron nitride works great too, but this is a messy white powder and expensive.

Also a thin layer of silicon carbide or boron nitride epoxy could be applied then a layer of cheaper carbon black or chopped carbon fiber mixed epoxy could be use for making a thicker layer if needed. Non-metallic heat sinks work great using these materials.

We were able to take a Antec 450 Watt Power supply and run it at full load with no fans or heat sink fins as just one big white sold block of epoxy with boron nitride.