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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?
Probably a lot easier to source yourself a few liters of Cray blood (or some similar non-conductive coolant) to submerge the board in instead.
Cheers,
The issue I see is with immersion. Sure you can coat the MB but what about the USB, VGA, etc connectors? Can you guarantee water will not leak in. Water has a way of getting inside any way it possibly can. Coating may be beneficial when you do not intend to put in case. Maybe to protect the MB as a bench system.
Wouldn't that conduct the heat from the CPU over to the other components?
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Except that conformal coating would not be the greatest idea for use with immersion cooling. You would have to coat everything together, including memory modules, pci cards, power connectors, etc..., making them permanently attached and impossible to replace if/when necessary. Since it seems Bat Country's intention for this is so that a non-conductive coolant is not required for immersion, leading me to believe water or some other electrically conductive coolant is to be used, you add the risk that the coolant may enter through small holes and cracks that may develop at the places where the components are connected, immediately bringing everything to a halt.
For immersion, the only sensible means is to use a non-conductive coolant and not worry about having to protect your hardware from the coolant it will be immersed in. It might be more expensive than just cooling with water, but it will likely be cheaper than having to replace ALL of your hardware that you just fried.
That's what he wants to do?
pfft. Waste of time and hardware. A leak will kill it.
Use something cool, maybe some old Cray coolant. It's out there.
deleting the extra space after periods so i can stay relevant, yeah.
Molding & Casting (through replica propwork and creature prosthetic effecs) is a hobby of mine, so here's what I know about resins. Maybe it will help
Epoxy resin is good at holding up to high temperatures. It comes in a variety of cure times and is available in small quantities at hardware stores and large quantities at marine supply stores. The fumes are smelly and unsafe, but they at least dissapate soon after curing.
Polyester resin (aka fiberglass resin) is cheaper than epoxy. It is generally weaker. It's fumes are quite nasty and hang around for days, so it's really an outside thing. It's probably no good for this task as uncured resin ravenously dissolves polystyrene (I don't know if PCs ahve polystyrene, but I wouldn't risk it).
Polyurethane resins come in the widest variety of formulations. It varies from hard as rock to a very flexible rubber, and any mixture inbetween. It is very low odor, but the fumes are still nothing to mess around with. Some formulations use metal fillers like aluminum (reduces shrinkage/thermal warping), so look out for that. It will certainly shrink a bit, so thicker coatings should be done with more flexible varieties. Shrinkage can be reduced by adding loose chopped fiberglass, though this does raise thickness.
Silicone rubber, particularly Platinum cure silicone has low to zero shrinkage. It's also by far the least toxic. It's also the most expensive by volume. again wide range of cure times, thickness/thixotropy can be adjusted by adding fumed silica (just don't breath the stuff). It is thermally resistive, so you will want to keep coatings thin, and suppliment it with submersion. Still, if I was tinkering around with such hardhacks, I suspect I'd go this route. Silicone is a great electrical resistor and has fantastic waterproofing abilities
for thin coats of any of these materials, you'll want to brush or spray the liquid to minimize airbubbles. All types resins have sprayable formulations, either by using specialty spray devices sold by the resin manufacturer, or by thinning the resin with the appropriate solvent. The more solvent you add, the more shrinkage is an issue, which is supplanted by applying thin coats in good ventilation.
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If you use the low power VIA chipsets like Eden you only have to dissipate under 10W of power, which these thermal goos could handle. But potting is very insulating compared to open air.
Don't forget the SSD. Standard hard drives won't handle any of this.
It might be useful to rethink the process and figure out what it is you are trying to address. Just moisture - conformal coating. Just vibration - make a better box? If you are strapping this to the outside of a Mercury outboard motor I would go with a better box.