Coating a Motherboard In Thermal Resin? 272
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?
SUN used to do it. (Score:5, Interesting)
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:Cray blood (Score:3, Interesting)
Extensibility might be tough. (Score:3, Interesting)
Re:SUN used to do it. (Score:5, Interesting)
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.
iPod in resin (Score:3, Interesting)
Anything like this?
http://www.engadget.com/2007/11/13/ipod-gets-exploded-trapped-in-resin/ [engadget.com]
You should see the IBM version (Score:5, Interesting)
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
Re:SUN used to do it. (Score:1, Interesting)
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.
nCipher does the same with their cards. The coating was an epoxy. The thought was that you would not be able to remove the epoxy without destroying the chips, there for removing any ability to pull keys off the card.
Re:SUN used to do it. (Score:5, Interesting)
It's common on high-tech boards (Score:3, Interesting)
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.
Re:SUN used to do it. (Score:2, Interesting)
I used to work for a company that makes cards like this (high security tamper resistant encryption cards).
While it is true that you can encase a card in resin (as a previous poster mentioned, it's called potting), you have to take into consideration the thermal profile of the components on the board. You can't just do it to any old card, and in our case it actually affected which embedded processor we went with.
cockroaches (Score:5, Interesting)
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 (Score:5, Interesting)
Yes it works (Score:5, Interesting)
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.
Does two-part epoxy count? (Score:3, Interesting)
I typically remove the plastic casing from all my little dongley peripherals and coat them with a clear, two-part, quick-setting epoxy. I've been at it for years now, and the only problems I have had have been cosmetic.
The trickiest part of the process is masking the pins, sockets, and other areas where you do *not* want to apply a clear, two-part, quick-setting epoxy.
I'm sure Vaseline or some similar masking agent can be applied and removed cleanly, given the right environment.
I usually do it on my kitchen table with a plastic knife. YMMV.
Re:Sticks and Glue. . . (Score:3, Interesting)
I think someone pulled the same stunt on our professor in the past, which is why we were given 6 36" sticks to build a 20" x 2" span. That enforced a somewhat more conventional approach. It's rather difficult to drive a car across a rope.
Re:Conformal Coating (Score:3, Interesting)
but epoxy isn't a good thermal conductor.. so even if your layer is only .001mm thick it is still an insulator between he heat source and the coolant..
infact epoxy makes a very good insulator - there for the heat would not go through it at all (to any reasonable measure) until it has blead out through the rest of the board.
what you would need to do is take your heat sources and place passive heat sinks connected via thearmal conductive glue - then epoxy the rest of the board leaving the heat sinks exposed for the coolent to move heat from
only issue is you need to seal the epoxy edge and the heat sink edge - that isn't going to be easy as the epoxy isn't going to expand or contract nearly as much as the heatsink is.
sealing something for full emersion into a conductive fluid and having it work .. is no simple matter
Re:Sticks and Glue. . . (Score:3, Interesting)
I think someone pulled the same stunt on our professor in the past, which is why we were given 6 36" sticks to build a 20" x 2" span. That enforced a somewhat more conventional approach. It's rather difficult to drive a car across a rope.
Suspension bridges are essentially made of rope. --It would take a lot of work, (and probably earn one of those dreaded high marks I routinely tried to avoid), but my immediate thought given the scenario you describe would be to game the system by building a suspension bridge using ropes made out of lines of glue strengthened with fibers from crushed up sticks. I'd probably find some way to lock my bridge the to table as well, even going to far as to drill holes beforehand, because I bet the rules didn't say you weren't allowed to modify the testing apparatus itself. That would raise some eyebrows, and that's the point.
Anything to avoid thinking as instructed. --The unspoken prime directive of the school system is to make people willing to limit themselves within authority structures. (You can only use X number of beams, because those are the RULES, despite what the real world might be like, you WILL get used to there being absolute definitions of reality so that when you do enter the real world, you will be pre-conditioned for easy control. You will ASK to go to the washroom and you will believe your text books!) --And this absolutely infuriated me on a fundamental level. It's the reason Slashdot is so incredible; these pages contain posts from literally hundreds upon hundreds of very smart people who nonetheless think in nonsensical absolutes without even being aware that they have been trained into a kind of blindness; all while truly believing that they have a superior level of awareness even while reality orbits in the most astonishing of ways few of them are able to see. It breaks my heart some days. But it is changing. I see a lot more people around here these days who question things.
My objective in school was to force the system to fail me even while completing the tasks assigned with more grace and skill than the 'good' students, thus demonstrating the fact that the objective of schooling is NOT the cultivation of creativity or intelligence, but rather the instilling an underlying and nearly-invisible level of social obedience at all costs.
I proved my point with flying colors, and despite being bounced from the system, (resulting in some very pissed off teachers and professors and zero student debt; I gamed that system as well), went on to be successful in life and even asked to return to lecture in a few cases. My only regret, (and it is a big one), is that I wish I could have done all of this without giving into anger and arrogance during the process. Because while I did find it funny, it was an angry kind of funny. If I had the chance to do it all again, I'd make one of my objectives to hold a sense of love and compassion throughout. It would have been a thousand times more effective than the combative route I chose.
-FL
SACDIN / SACCS (Score:3, Interesting)
I remember they were glossy, and for fun we tossed them around, hit them, generally tried to break them...but could not. They were nuclear radiation and EMP hardened, and when I struck them with my Air Force ring, containing a stone that is supposed to be extremely hard to scratch, the ring scratched instantly and deeply. I've scraped it along a great deal of metal and stone objects, never adding any new scratches.
Finding the right stuff such as the SACDIN boards were coated with can be very fun indeed.
Re:Sticks and Glue. . . (Score:3, Interesting)
In our case, it was considered an engineering problem, so there were certain inviolable constraints, but as long as we satisfied those we were free to do whatever we pleased. I'm sure plenty of composite construction techniques could have improved our results, but given the time constraints and the fact that any wood used in testing came out of the total available for construction (quite reasonable real-world engineering constraints) we were forced to innovate conservatively. We hadn't been taught anything about surface lamination, so the glue technique was certainly creative, but applying that reinforcement indiscriminately turned out to be less efficient than applying it judiciously in the places where it was needed the most.
Engineering doesn't stifle creativity, it just guides it in a more practical (and often less exotic) direction than pure science. If my motherboard had been designed by scientists, maybe it would have used the original poster's proposed technique, but it would have cost much more, and I would have bought a different one instead.
Re:Potting blocks air cooling, of course (Score:3, Interesting)
http://en.wikipedia.org/wiki/Heat_pipe
Try before you Post? (Score:3, Interesting)
Ummm... why don't you simply try it out? Motherboards are pretty cheap these days; try doing this, and write of your experiences. Much more interesting than simply asking "Should I do this?".