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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?
yeah, it's called conformal coating
But won't the fans stop turning and cause it to melt down?
"Eve of Destruction", it's not just for old hippies anymore...
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?
The technical term you're looking for is Potting.
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.
"Ein Volk, ein Reich, ein Führer." -Adolf Hitler
"We are one Nation, we are one People." -The One 'leader'
Tomshardware had a computer in a fishtank full of mineral oil a bit ago. Works well but what a mess.
http://www.pugetsystems.com/submerged.php
...with electronics sometimes using a type of Epoxy... sometimes it's just to protect the circuit physically, but I've also seen it done (with a high temp resin and a black pigment) when distributing early samples of products-in-development in order to help protect the circuit from prying eyes... in order to make it a little less trivial to copy etc...
I've not known it done for the purposes of heat disspation though, I'm not sure how-efficient of a thermal conductor a non-electricly conductive solid resin would be...
This sounds almost exactly like something I did back in nineteen dickety two. We had to say "dickety" because the Kaiser had stolen our word for "twenty." I chased that rascal to get it back, but gave up after dickety-six miles.
I'm a big tall mofo.
Do a google search on it, or check out the funky aquarium at:
http://www.pugetsystems.com/submerged.php
Old age and treachery almost always overcome youth and skill.
NASA did something like this for the computers on the Apollo missions.
I'd imagine you'd want to sort out your future memory or disk capacity needs before dipping.
Yeah? Well I think you're overrated too.
It is electrically insulating and is commonly used for cooling electronics (think Cray supercomputers).
Part of the problem with conformal coat is that it makes it hard to service the electronics after it is cured. It also may or may not be uniformly distributed and thus may not pass muster in a tank of conductive liquid.
There are conductive epoxies like Stycast, but they're not particularly good conductors. The only reason to do immersion cooling is for good thermal contact to all components. A thick epoxy layer between your components and your liquid will quickly destroy that advantage.
Also, if you have connectors to the circuit board (like PCI connectors), then you cannot fill the pins. Last time I checked, most PCI connectors are just slots and have no bottom fill. Water will certainly get in under the coating through the slot.
Hrm, RESIN! what an idea!
I tried coating my motherboard in the coolant H2O a few years back, did not improve my motherboard's temperature one bit ... nor the performance for that matter.
Anything like this?
http://www.engadget.com/2007/11/13/ipod-gets-exploded-trapped-in-resin/
Terrorists can attack freedom, but only Congress can destroy it.
Potting is used to keep the components from moving (usually in high-G environments. Sometimes you use it to keep close conductors from shorting (like solder-cup connector), but again the risk there is mostly movement of the conductors, not the environment. Potting materials usually do not have good thermal dissipation properties, and aren't really the best thing for environmental protection (humidity, liquid immersion etc) either. Conformal coating is what you want for the latter.
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
If you'd do that, you would have to do it after you sintalled every component... and sealing all the wires, including the ones to the power supply and case, so if some component would have to be changed, it would be a nightmare and you would basically have to remove the whole sealant or scrap the computer...
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.
People have been running PC electronics submerged in mineral oil for decades.
Advantages:
1. Not too hard to do
2. If push comes to shove, you can can probably burn the PC in your fireplace or other suitable container to keep warm. Or just because you are pissed at it.
Problems:
1. It's messy.
2. The oil tends to creep up any wires to the outside world (capillary action?) and eventually show up at the other end.
3. I'm not sure if non-gas tight connectors are used in modern PCs, but if they are, they may be a problem.
4. It's messy.
Did I mention that it is messy?
You can't see ANYTHING from a car, You've got to get out of the goddamned contraption and walk...Edward Abbey
Power supplies for the C-64 were 'potted' as were many power supplies of the day. Can't see why it would not work.
Gregor
Electronics has to be designed for potting, at least if it dissipates any significant power. You have to provide a heat path (usually a metal heat sink) out of the potted block. This is done routinely for DC-DC brick power supplies. But it's not going to work on a PC motherboard.
the curing properties of whichever material you choose. The ratio of resin to hardener can affect the shrinking, which can disturb components. Also, the heat kicked out by a CPU may be able to melt the coating if the mixture has too little hardener. If you go ahead with it, bang it on a blog, I'm sure there are others who would like to read it.
I figured I'd save a few bucks by doing my own water cooling and using some seals from a hardware store. The problem was that the seal wasn't perfect and it melted to part of my pc. Needless to say, if you are not worried about ruining your hardware, then by all means, go for it. But I would google anything you are trying to do/use and make sure the parts are definitely capable of withstanding the punishment you are about to put on it. If not, your great idea may go to the wayside because of insufficient materials.
Anything and Everything about the Net
"You shot my heat sink! Now where am I supposed to sink my f***in heat?"
Tsukasa: All I really want, is to be left alone...
...and it's a well known process - i've seen devices from the '80s with epoxy encased parts. Keep in mind though potting does practially nothing for heat dissipation. Even if you managed to get your hands on some thermally conductive resin, in PCs the principal way of heat dissipation is forced convection (coolers, that is), which allows to use very small dissipators for the given power. I don't think you could find a substance that allows good thermal transfer without a large surface area - meaning, a lot of resin.
If you're planning to pot and then submerge in Fluorinert or a similar compound, the resin coating, no matter how good transfering heat, will only raise the working temperature of the parts.
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.
> ...or just go buy mineral oil and spare yourself some strange looks at the vet's office.
I'm sure the vet will be understanding when you explain that you don't actually have a horse, you just want to dump the laxatives into your computer. Why would they give you strange looks?
MG Chemicals' Part number 832-TC. Conformal coating doesn't conduct heat well and is designed for a very thin coating.
You'd probably want to make sure any heatsink fins are exposed though.
I agree - immersing a contact connector is a bad idea. The fluid will eventually get in between the leads. So, just solder jumper cables directly to the motherboard and have them poke up out of the brine.
Probably a good idea to solder your PCI stuff directly to the board too, if you can.
Weaselmancer
rediculous.
You mean with something like this?: http://golden-shellback.com/
This is pretty much your guide to getting it done.
Thank you Futurama:
It must have been something you assimilated. . . .
http://www.plastidip.com/
I've used this for years to coat electronics for exposure to the elements. Boards up to 6x6".
It can be cut away and removed if necessary and then reapplied.
Not sure about the heat tranfer characteristics, tho.
Your mileage may vary, etc.
Beta sux! Join the Slashcott! http://hardware.slashdot.org/comments.pl?sid=4760465&cid=46173047
and if you're cheap, people will actually pay you to take PCBs off their hands.
"National Security is the chief cause of national insecurity." - Celine's First Law
Like most thermal compounds it may conduct heat better than most non-metals but unless it's a brand new material everything on the market currently is going to be a far worse conducter of heat than air. Encasing thermal components in a material with worse performance than air is going to make them get much hotter.
I had a mackintosh (sp?) vacuum tube amplifier in a metal case circa 1950. When the top was removed all one could see was black potting compound enclosing all the components except the connectors and tube sockets.
In my former life I worked as an industrial electronics technician. My job was, in a nutshell, to modernize a manufacturing plant from its 1950s style, analog (pneumatic) technology, to digital electronic distributed control systems.
The environments these devices need to work in are quite harsh, with extreme temperatures and often corrosive atmospheres. The pneumatic control systems were quite robust in those environments... electronic devices need a lot of beefing up to survive these conditions.
One aspect of this was to treat all circuit boards with a conformal resin coating. The trick is to make sure the thermal coefficient of expansion of the resin, matches the expansion of the circuit board material. I am not a chemist, but I do know such coatings are available.
Another consideration which has been mentioned is how to treat connectors. The usual method is to apply a rubber like sealing compound after a connector is fitted and tested.
For less extreme environments, a much less expensive, but quite effective alternative, is to apply a cheap acrylic coating, using readily available sprays such as Krylon 1301. The procedure is...
Assemble the device (uncoated) and test thoroughly.
Disassemble the device.
Apply tape and / or petroleum jelly to connectors and contacts, to prevent damage from the spray.
Apply the spray to each component.
Assemble and re-test.
Hope this lights a bulb for you.
The characteristic impedance of the surface traces will change.
The surface traces were designed with the assumption that there is air above the traces.
Loading up a bunch of gunk will change the impedance, and could screw up your signal integrity. PCI Express or Gig Ethernet could fail for example.
Google stripline vs microstrip and signal integrity of high speed differential traces.
I'd be curious how the conformal coating people manage this too, I'd assume the copper trace widths would have to be designed knowing the board was going to be conformal coated.
Bavarian Purity Law of Rice Krispie Squares: Rice Krispies, Marshmallows, Butter, Vanilla.
a diamond coating. The only material that fulfills your demand for high thermal conductivity and good electrical insulation at the same time. The only problem is that the one good method to apply a diamond coating is chemical vapor deposition, and that is mostly line of sight. So you'll have a real tough time coating around those 1000 pins under your cpu.
I'm aging rapidly, I bought a new game and had no idea if my machine was good for it.
Potting boards is common in military applications. But it makes 'em harder than heck to repair.
If it's just a coating, you can sometimes scrape it off enough to put in a new component, and then pot over it. The potting residue makes it difficult to solder and trying to remove it puts the traces and pads at risk. Nasty, but can be done.
But if it's completely potted, like a brick in which you can dimly see components, when it fails you just throw it away. No point in trying to fix it.
In your case, you have to ask yourself things like how you're going to replace the bios battery.
Oliver's law of assumed responsibility: If you're seen fixing it, you will be blamed for breaking it.
Was it a crossup of lung-searing odors like magma of fresh/raw bowel-manure (laden with fast-food/processed-food chemical additives), burning rubber, oozing/gangrenous pus, aged milk and off-brand bleach? You'd need not only a HEAT sink, but also a STINK sink. PHEW...
Previously: "Linux... Toward the Sunrise..." Now: "Linux... Toward the-- No, now, part of Every Sunrise"
That computer board will be worth less than a molten pile of horse shit. Horse shit is recyclable. Even some of the hay in it. But, a molten/slagged, PCT/other chemicals-infested MoBo?
Previously: "Linux... Toward the Sunrise..." Now: "Linux... Toward the-- No, now, part of Every Sunrise"
Yes this can be done. It is done. But in engineering we typically work from a set of requirements. This means we get a spec that says the part must fit in a given space or use only so much power or whtever. What you have is a solution looking for a requirement. In other words "I want to epoxy pot my M/B - Why would I do this"
If you must use this type of cooling why not simply us a nonconsecutive liquid? If you potted the M/B you'd have to pot all the conctors too. You never be able to replace a cable or RAn or move a jumper
The other thing that engineers get paid to do is come up with cost effective designs. In terms of cost this is just the wrong way to go.
The best way if you wont a compact and silent machine is to use the case itself as a heat sink. Conduct the heat to an aluminum case and let it radiate. Use a termally controlled fan as a backup for hot days and high loads. Oh wait isn't that what Apple does?
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.
I am always doing that which I can not do, in order that I may learn how to do it. - Pablo Picasso
His project was to create a submersible CPU. He ruined several motherboards before perfecting it. He did use an industrial sealant, but it was not thermal resin. His problem was making a completely sealed unit as the motherboard was completely dunked in water.
I think I have his project notes around somewhere. I'll see if I can find them for you.
Thermally conductive materials are generally pretty good electrical conductors. It ain't gonna' happen like you asked.
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.
I also wonder if this would help stop the spread of Tin Whiskers http://en.wikipedia.org/wiki/Whisker_(metallurgy)
It sounds like you might have luck using a thermally conductive epoxy. There are many grades, and they vary in viscosity, conductivity, strength when cured, and operating temperature. Have a look at those offered by Epoxies, Inc. at http://www.epoxies.com/therm.htm
See http://www.octools.com/index.cgi?caller=articles/submersion/submersion.html
Necessity is the plea for every infringement of human freedom. It is the argument of tyrants; it is the creed of slaves.
It's a few hundred dollars, at most, to test this theory. Go try it. I promise the results will be more useful and interesting than anything you'll get back from Slashdot (e.g. theories on mineral oil suspension, stories on potting mainframes in the 70s, etc.).
10 years ago when I got into this racket super cooling Durons to hit the 2Ghz mark with stuff like Vodka and Peltier Plates, I ran into an old air force MI guy. He said back in WWII/Korea they used to completely emerse their high altitude aircraft electrical circuits in vats of dielectric oil, and it's in these tubs that they ran. It prevented water moisture, prevented freezing and brittleness, prevented everything. The only two drawbacks to it was it was heavy and it was messy. But back in the day, this is how it was done.
the chocolate icing!
Sig this!
If you want to do this for cooling purposes, why not immerse the entire system in a non-electrically-conductive coolant?
use a non-conductive liquid for cooling, such as oil. This has been done before, and even a cursory google turns up lots of interesting results.
Coating is a waste of time, and it's very difficult to get a good coating over empty expansion slots, USB slots, etc., let alone those with cards in them.
https://www.eff.org/https-everywhere
I see a lot of comments about the immersion side of things, for which I know it would probably be a lot cheaper to just pick up some nonconductive coolant.
How about other reasons for doing it - specifically shock resistance and hardening against slippage caused by vibration?
Additional value could be found in potting the board in marine/cave/jungle environments where the hardware might be exposed to caustic and humid air.
Also, presumably resin coating might get around problems with hungry insects. I'd imagine a really well designed medium-tight case suspending the components in a nonconductive coolant might work, but it seems like it would be a more bulky solution.
However, I'd be interested to hear of better solutions than coating the whole shebang in toxic goop.
The land shall stone them with the bread of his son.
toms hardware had an oil cooled one using silicone of all things
http://www.tomshardware.com/reviews/strip-fans,1203.html
Immersion in mineral oil. Need to remove all fans and other spinny things, and you won't be upgrading anything afterward. But it does work, and permits totally quiet computing.
Long as you don't mind the, you know, tank.
There are such resins, but:
1. They are really expensive; $100 is about 2" sq, half an inch thick.
2. It has to be cast around the electronic assembly in a vacuum; this is harder than it sounds.
3. To cure properly, and without voids, it has to be poured into a custom mold at around 150C. In a vacuum. :)
I have seen electronics cast like you are talking about, but I doubt a mobo would take the process and live. The casting temperature is too hot, and kills most electronics.
If it worked, you could dunk the whole thing to cool it. Liquid Nitrogen would even work, as long as the thermal shock was controlled. Cool or heat it too fast, and the stuff breaks.
The standard procedure for the assemblies I saw,was to make 10, and hope a few work afterward.
Truth isn't Truth - Guliani
I don't think you could find a substance that allows good thermal transfer without a large surface area - meaning, a lot of resin.
This Google search turns up some neat materials.
My God, it's Full of Source!
OUTSIDE_IP=$(dig +short my.ip @outsideip.net)
It's not resin, but it's also a nice alternative
http://thedailywtf.com/Articles/Silent-But-Deadly.aspx
The contest was to build the most weight-efficient bridge, using only balsa wood sticks and wood glue. Efficiency was judged by (failure load)/(bridge mass). The highest load, by far, was born by a bridge that had been totally coated with wood glue. Unfortunately for them, this coating raised the bridge mass by nearly 50%, so their bridge was still less efficient than my team's, which used a more conventional truss design, with a coating of glue around the joints. Nearly every bridge in the class failed first at a joint, so reinforcing the beams themselves was a waste.
The point is that applying the same reinforcement everywhere tends to be a serious waste of resources that would be better applied to the most critical areas. This is why my shiny new motherboard has a few components embedded in epoxy, surrounded by metal heatsink-like rings. Unlike other motherboards I've used, this one has no large components sticking up from the PCB, so I'm guessing that they singled out those bulky components, shrunk them down, and then added the epoxy and rings to allow them to operate safely at a smaller size.
There's no failure quite as dissatisfying as a complete and total solution to the wrong problem.
Beryllium Oxide powder and turn on the fan. That will really cool it down. Beryllium Oxide is an excellent insulator and heat conductor. ahem.
Is there such a thing?
Would that work for many situations where one needed both thermal transfer and sealing, both?
It couldn't be impossible, could it?
A company I worked for used to pot their circuit boards but changed over to conformance coating instead due to issues already pointed out by several people in this thread.
They do make thermally conductive epoxy, but the CPU will still need a dedicated heatsink/fan
http://www.mgchemicals.com/products/832tc.html
Pot? Check!
Bong? Check!
Big hit? Check!
Err... what the hell was I doing with 5 gallons of horse laxative?
I think this is a product that should do what you're looking for. I haven't had a chance to use it yet, but the info at the link leads me to believe it could fit the bill. Masterbond-Potting & Encapsulation Materials http://masterbond.com/produse/produse_pe.html
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.
I've done business with all the major online (US) retailers. I've had excellent experiences with all of them; be sure to take advantage of personal customer support. For more information check out http://polytek.com/ http://smoothon.com/ and http://tapplastics.com/
Hm. I remember doing that exercise as well. --I think the scoring formula needed to be adjusted, because my solid bundle of sticks soaked in glue creating basically a polymer enhanced log could take all the weight the testing apparatus was able to provide, plus that of the teacher and two students standing in a rope looped over my 'bridge'. It never broke, thus my ham-fisted design won the contest despite the ridiculous number of pieces used to make it.
It was also generally agreed that I was an ass and that the real winner was the team which had came up with one of those conventional erector-set type designs.
The point which led me to this idea was that I'd noticed in the scoring formula there was no limit on the amount of glue we were allowed to use. I'd considered making a solid log of glue with a single strut buried inside it, but the drying times wouldn't have allowed me to finish the project before testing day. I think one of my purposes in going through the school system was to spend as much energy as possible challenging the silliness of conventional thinking, though at the time I was giggling too much to take notice.
-FL
And Chinese food Holy diarrhea. /.
fsck
http://www.octools.com/index.cgi?caller=articles/submersion/submersion.html
Just disrupt the deflector shield with a tachyon burst.
"--for the purpose of immersion, shock resistance, whatever."
Eurotech Finland http://www.eurotech.fi has some nice candy, look in http://www.linuxdevices.com for other manufacturers.
http://hardware.slashdot.org/article.pl?sid=08/08/27/1930214
I don't have time to check that link again, but I recall it was hundreds (maybe a thousand?) £ per litre. Looks awesome though!
Nick
I once had the pleasure of 'removing for proper disposal' a great deal of circuit boards used in the SACDIN systems. (http://www.fas.org/nuke/guide/usa/c3i/saccs.htm)
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.
Who is this that even the wind and the waves obey Him? Surely this computer must submit also!
As mentioned a million times already, hard coatings are more insulative and will keep heat in. So a liquid is the way to go.
How about propylene glycol?? Any chemists out there? Automotive propylene glycol- $10/gallon- less on sale. Should be very non-corrosive. Hmmm- might be electrically conductive, which would kill the board. I'll go run some tests...
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?".
Free PC version of ChipWits at http://www.breueronline.de/klaus/chipwits/
'nuff said
It was done quite a few years back by some NZers who immersed the entire working computer in some liquid from 3M(I think)
At the time it was 1500US dollars a liter.
They overlocked some Celeron 300A I think to around 600 or so mhz, no idea if the pics or info of it is still around
Its not clear what the poster is trying to do. Conformal coating or potting may not be a good option. Is he trying to protect the board from dust, an occasional spraydown, or condensing humidity? Maybe CC or potting would work. THough the heat issues would be pretty bad as mentioned 100 times above.
I would recommend a pressure housing with o-rings and proper feedthrus or liquid proof connectors. For high pressure and heat dissapation, filling the pressure housing with Flourinert would be a nice solution, just put a small pressure compensating bladder on the pressure housing so little air bubbles aren't a problem.
If one is pressed for time, a really good ziplock bag filled with Flourinert, and a potted feedthrough for the wires would also work in a pinch.
A friend of mine produced a hand-held electronic device in which he had sealed the electronics with a fairly thick epoxy coating. This had the effect of making it water-, shock- and crushproof.
However, it never generated any waste heat during use. So I don't know how well this would work on a motherboard, which we are all aware can generate a lot of heat!
My approach using this technique would be to give the motherboard an initially thin coating. Then, carefully lay some tubing for water cooling over the motherboard, with extra loops around the CPU and other components that might generate more heat than others, and then give the whole assembly a thicker coating of resin to finish it.
I suggest adding water cooling, because even though the resin may be thermally conducting, it is also going to be conducting that heat in three directions. For example, not only will the resin be conducting heat away from the CPU, it will be delivering that heat to the components around it until the heat begins to bleed out of the surface of the resin. So it would be wise to add cooling to remove the heat from the resin as quickly as possible.
Whew! This water sure is cold!
http://www.heatsinkfactory.com/non-conductive-coolant.html Cheap non-conductive coolent. $64/gallon
How many more years will slashdot have an off-by-one error on your Score in your profile?
Golden Shellback Waterproof Coating on Vimeo
Parts of the mother board run at very high frequencies (the cpu pins). The change in capacitance between the pins may play havoc with the functionality. The guys who oil cooled their pc ran into it.
-- Programming with boost is like building a house with lego. It's a cool but I wouldn't want to live in it
Seeing as you're getting a lot of comments about cracks, immersion shorts, replacability, and cost, what if you modified the idea a bit...
I'm thinking, immerse the board in oil:
http://www.tomshardware.com/reviews/strip-fans,1203-4.html
Then seal it in watertight container, maybe something like:
http://www.opticsplanet.net/pelican-1450-protector-medium-waterproof-case.html
So this would be:
thermally conductive - check
electrically insulating - check
immersible - check
shock resistant - maybe?
You'd need to puncture the case to allow for heat exchange, cabling, etc, but the oil would leak out of any water-permeable joints, so a completed project would likely be quite well-sealed.
If you wanted a completely-contained PC, and clear plastic and an LCD to the side. Plus Wifi and Bluetooth, waterproof keyboard/mouse/whatever. You could have quite the critter on your hands.
Just a thought...
the Stanford Prison Experiment.
They ARE out to get you simply because They are in it for themselves and they don't care about you.
Try ice
www.totl.net/Eunuch
486 & Half Life Ha Ha
fill a big ziplock bag with sand, stick your board in there and cackle.
---------
No matter how thin you slice it, its still baloney.
I once saw on the net somebody who made a video of them immersing an entire setup (except the PSU) into heat conducting non-electrical conducting oil for a serious overclocking attempt. Of course all chipset and graphics card fans were removed or deactivated. That worked great for the heat. If one could suspend a computer setup in an oil cube casing then it would get both superior cooling and also be very schock absorbing. That would also open up for a pump or sort of external oil cooling system to be used, if the heat exceeds the oils capacity to coll the setup. So if you imagine 8 springs holding a mouting backet/plate in mid air attached to the 8 corners (and perhaps a couple of sides) inside a closed cube that is filled with high density non-electrical conduting oil and having no air (cube filled to max. possible) , then thats my idea to make a schock absorbing, high cooling solution. Of course this would also call for the usage of solid state disks, since they don't rotate and need a breathing hole. And SSD's are very shock proff too :)
What kind of dog barks "BOFH! BOFH!"? A rootweiler of course...
it's just about the most annoying thing a technician will ever have to spend an hour scraping off with various spoons sporks knives and picks only to fix 1 burnt trace and then reconform it.
It's really an EXTREMELY annoying coating as it renders a lot of otherwise simple pcb's not practical (due to the costs of human scraping) for repairs.
That aside, I'm a bigger fan of the notion of heatsinking and proper housing design than the "let's just coat the sucker in half an inch of glue-gun crap" approach some manufacturers opt for.
Ah, yes. 3M Fluorinert. That stuff seems to pop up here in discussion every once in a while. I don't believe they actually manufacture it anymore -- what you can buy is basically "New Old Stock" -- and it's staggeringly expensive. (For the home hobbyist, anyway; if you're actually maintaining a Fluorinert-cooled system in production, it's probably nothing.)
The common alternative you can play with at home is mineral oil, although it's not nearly as good. What makes Fluorinert useful is its relatively low boiling point. It's liquid at room temperature and on most idle parts, but on a hot component, it will boil. It's the boiling, not just the submersion in liquid, that draws the heat away so effectively. Most home liquid-submersion experiments miss this entirely.
Personally I've always wondered about coolant solutions that use the solid/liquid state change rather than the liquid/gas one; maybe a slurry of solid, low-melt-point crystals suspended in a liquid carrier. I've worked with some plasticizers that have basically room-temperature freezing points, but I've never seen that particular property taken much advantage of. (Most of them actually become more dense as they freeze, rather than less dense like water, so you could put your hot parts at the bottom of a tank filled with slurry, and when the coolant melted the liquid would rise to the top and more frozen coolant would fill in over the part. It would be similar to Fluorinert boiling, but without the gas production.)
"Ladies and gentlemen, my killbot features Lotus Notes and a machine gun. It is the finest available."
Take a look at the Parylene process. The ultra thin coating does not interfere with cooling (conductive, convective, or radiative)
Remember the wavy lines that used to go across the screen after the "FIBERGLASS" motherboard got too hot?
ROTFLMAO!!!
Gotta admit though... they pumped out a shitload of those and most of us got a start on them at that young age.
YAY Commodore!
The electrically non-conductive Cray coolant is called Flourinert.
Can I still upgrade my RAM, video card, etc? If not, sorry, come up with something better, because this is simply insufficient.