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Coating a Motherboard In Thermal Resin?

timothy posted more than 6 years ago | from the oh-did-you-want-to-use-it-afterwards-too? dept.

Hardware Hacking 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?

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I coated your mother in chocolate resin (-1, Offtopic)

Anonymous Coward | more than 6 years ago | (#24865037)

But it only heated her up more.

Conformal Coating (5, Informative)

DeathOverlord3 (645635) | more than 6 years ago | (#24865049)

yeah, it's called conformal coating

Re:Conformal Coating (5, Informative)

Anonymous Coward | more than 6 years ago | (#24865267)

Conformal coat is generally a thin film applied over the board and components. I get the idea he is talking about something more like 'potting'.

Potting blocks air cooling, of course (5, Informative)

Animats (122034) | more than 6 years ago | (#24865465)

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 [coselusa.com] power supplies. But it's not going to work on a PC motherboard.

Re:Conformal Coating (4, Informative)

Ethanol-fueled (1125189) | more than 6 years ago | (#24865273)

Conformal coating [wikipedia.org] is protection against a lot of things, and submersion is not one of them.

Those of us who work in the electronics industry know that doing CC in-house is a bitch and inspecting an outsourced job is an even bigger bitch, especially when you're dealing with military parts.

Re:Conformal Coating (5, Interesting)

DeusExMach (1319255) | more than 6 years ago | (#24865499)

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...

Re:Conformal Coating (1)

whoever57 (658626) | more than 6 years ago | (#24865529)

Conformal coating is protection against a lot of things,

I think most conformal coatings are not good at heat transfer, which might make coating a PC motherboard problematic.

Re:Conformal Coating (5, Informative)

Animats (122034) | more than 6 years ago | (#24865353)

Right, it's conformal coating. People do that all the time. I've used Fine-L-Kote on boards.

Boards with connectors or jumpers have problems. If the CPU and RAM are soldered to the board (as they often are in industrial, consumer, mobile, and automotive devices), just mask off the connectors, jumpers, switches, battery contacts, etc. with masking tape and start spraying. Fine-L-Kote is transparent, but glows in UV, so you can use a UV lamp to check if you missed anything. There are much heavier coatings, ones that really encapsulate the board, and those are widely used for automotive, boat, and aircraft applications.

PC-type motherboards aren't a good choice for this, because of all those connectors. Those are a weak point for corrosion anyway, so protecting the soldered-in components may not be all that useful. But if, say, you're putting something like a single-board PC on your boat, it's quite reasonable.

Re:Conformal Coating (5, Insightful)

Raistlin77 (754120) | more than 6 years ago | (#24865365)

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.

Re:Conformal Coating (4, Insightful)

rickb928 (945187) | more than 6 years ago | (#24865591)

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.

Re:Conformal Coating (5, Informative)

effigiate (1057610) | more than 6 years ago | (#24865419)

We conformal coat our circuit boards at my current job and I can assure you that it is not what he's looking for.

Conformal coating is typically a thin layer of silicone/urethane/acrylic used to keep moisture from getting at the parts on the board. It can not sustain immersion in liquid.

He's looking for epoxy potting, which we also do occassionly. The trouble with epoxy potting is getting the heat out of the board. You need to leave the thermally conductive parts outside of the potting so that you can remove the heat. The epoxy itself isn't thermally conductive enough to get processor heat out, even on a processor with passive cooling.

You can do this yourself if you have enough time and epoxy, though I'm not sure how much success you'll have. A failed attempt probably means a board that is no longer useable.

The very best ones get cured in a vacuum so that all of the air bubbles are pulled out. There are many other types you can use that don't require a vacuum.

Re:Conformal Coating (4, Informative)

Zadaz (950521) | more than 6 years ago | (#24865827)

I wonder where he could readily get a vacuum chamber big enough to pull the air out. Getting the air bubbles out is going to be pretty vital to not baking the mobo, especially the cavities under components.

The most readily available vacuum pumps are smaller than a full motherboard + components, used either for basic science, paint or latex molding. Maybe call up Tap Plastics [tapplastics.com] or your local university and see if they have a big one you can borrow. Because you're going to need a real one. A vacuum cleaner on a Tupperware box or a concrete vibrator isn't going to get what you need.

But my main worry is about thermal expansion. When motherboards get hot they don't expand evenly. Locking everything in resin, not mater how thermally stable, will put a lot more physical stress on the components. And you won't be able to do a damn thing about it except chuck it in the bin and start over again. Though this would probably be lessened with a smaller form factor and lower energy components.

Potting compound (0)

Anonymous Coward | more than 6 years ago | (#24865555)

MG Chemicals' Part number 832-TC [mgchemicals.com] . 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.

Re:Conformal Coating (1)

MHz-Man (1066086) | more than 6 years ago | (#24865577)

Have you ever used that stuff? It STINKS, and I mean in a way nothing I've smelled before or since has. It had this chemical smell that stayed with me for the rest of the day and ruined my dinner several hours after I was around it.

Correct me if I'm wrong... (1, Funny)

HotNeedleOfInquiry (598897) | more than 6 years ago | (#24865071)

But won't the fans stop turning and cause it to melt down?

Re:Correct me if I'm wrong... (2, Insightful)

Anonymous Coward | more than 6 years ago | (#24865157)

If you use immersion, why do you need fans?

Re:Correct me if I'm wrong... (1)

tmosley (996283) | more than 6 years ago | (#24865163)

You only need fans when the board is exposed to air. This is for immersion in a liquid of some sort. If I'm not mistaken, you can actually take a regular motherboard and submerge it in oil with no other preparation as a super heatsink without damaging it.

A handy side effect is that you can use it to fry up some food right in your case without even having to get off of your fat ass and go into the kitchen.

Re:Correct me if I'm wrong... (1)

Now.Imperfect (917684) | more than 6 years ago | (#24865833)

without any sort of fluid movement the board still heats up really fast. I recommend either putting pumps in it or placing some fans in it to move the fluid around, even better if you can force the fluid through a radiator.

Cray blood (4, Insightful)

Ritz_Just_Ritz (883997) | more than 6 years ago | (#24865083)

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,

Re:Cray blood (2, Interesting)

COMON$ (806135) | more than 6 years ago | (#24865167)

Ya I had a friend do this with a web server, for kicks of course, the sucker ran fantastic. Was some kind of nonconductive fluid he got on the cheap. Only trick was he had to separate the CD-ROM and hard drive but other than that it ran for a long time, fans and all.

Re:Cray blood (1)

hitmark (640295) | more than 6 years ago | (#24865369)

thats what one have esata, firewire and usb for.

Re:Cray blood (3, Funny)

adolf (21054) | more than 6 years ago | (#24865447)

Either you're new here, or you've misspelt "ethernet."

Re:Cray blood (0)

ChronoReverse (858838) | more than 6 years ago | (#24865501)

eSATA stands for External SATA and is indeed a competitor to Firewire and USB for external hard drives. The current specification doesn't include a source of power though so eSATA is only good for speed. The next revision is supposed to have power too.

Re:Cray blood (1)

spire3661 (1038968) | more than 6 years ago | (#24865643)

I have seen PCI(e) eSATA boards that have a round power out port right next to the eSATA port.

Re:Cray blood (1)

hitmark (640295) | more than 6 years ago | (#24865615)

well thats also a option, but one i would usually consider for more elaborate and distanced setups.

as in, you usually need two working computers for a ethernet based storage system to work.

Re:Cray blood (1)

SoapBox17 (1020345) | more than 6 years ago | (#24865277)

You're probably thinking of fluorent, which is an inert (doesn't conduct electricity) liquid used for a variety of tasks. That'd be a good idea except:
1) That stuff is usually really expensive, which wouldn't be so bad except...
2) The stuff evaporates really fast, and
3) If you get any dirt/etc in it then you will need to filter it or completely replace it.

Re:Cray blood (3, Insightful)

gardyloo (512791) | more than 6 years ago | (#24865337)

2) The stuff evaporates really fast

Some does, some doesn't. I've worked with the HFE-7500 stuff, which DOES evaporate really fast (much, much faster than water) -- as a result, you can also smell it a little bit, which can be annoying after a while. It also has a pretty low viscosity, which means that it tends to leak through any seals.
      On the other hand, the FC-73 stuff (which I've also worked with, though not as much) doesn't evaporate NEARLY so fast as water, and is more viscous, so it doesn't leak very quickly. It also doesn't attack silicone seals nearly so much as the HFE. For home hobby stuff, I'd recommend FC-73 over HFE.

Re:Cray blood (3, Informative)

Prune (557140) | more than 6 years ago | (#24865537)

FC-77 is intended for computer use, not FC-73 (my friend's father works at 3M)

Re:Cray blood (1)

ragethehotey (1304253) | more than 6 years ago | (#24865621)

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,

A Google image search brought up nothing for cray blood, could you provide a link?

Re:Cray blood - or Cheetah blood ... (0, Offtopic)

fahrbot-bot (874524) | more than 6 years ago | (#24865677)

... if you want the system to run faster.
  • Fry: Go after him, Leela!
  • [Leela pushes the throttle forward. The engines struggle.]
  • Leela: It's no use. We were going full speed when we fired him so he's going even faster than that.
  • Fry: You mean we can never catch up to him? Not even if we rub the engine with cheetah blood?
  • Leela: I don't know how to say this, Fry, but Bender is doomed to drift through space ... forever.

Thank you Futurama [futurama-madhouse.com.ar] :

Yeah... (1)

msauve (701917) | more than 6 years ago | (#24865707)

and if you're cheap, people will actually pay you to take PCBs [wikipedia.org] off their hands.

Not sure (5, Insightful)

linxdev (1020223) | more than 6 years ago | (#24865089)

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.

Re:Not sure (4, Informative)

MozeeToby (1163751) | more than 6 years ago | (#24865143)

That's why you don't use water, you use something non-conductive. Mineral oil is a relatively cheap and widely available option (just go to your vet and ask for a few gallons of horse laxative) if you don't want to spend the money on commercial grade cooling fluid.

Re:Not sure (5, Funny)

Lurker2288 (995635) | more than 6 years ago | (#24865205)

...or just go buy mineral oil and spare yourself some strange looks at the vet's office.

Re:Not sure (5, Funny)

Anonymous Coward | more than 6 years ago | (#24865305)

You: Hello Doctor! 5 gallons of your finest horse laxative please!

Vet: Oh, got a sick horse then? Are you it needs a laxative?

You: No, it's for me, eh I mean, it's for my computer!

Vet: Ah, the computer! I see. Say no more. *wink wink*

Re:Not sure (1, Funny)

Anonymous Coward | more than 6 years ago | (#24865691)

The parent's example sounds best when envisioned as an exchange between Radar and Colonel Potter.

Really. It almost sounds like something out of the show.

Re:Not sure (1)

MozeeToby (1163751) | more than 6 years ago | (#24865321)

Now what would be the fun in that?

What's so odd about that? (0)

Anonymous Coward | more than 6 years ago | (#24865513)

> ...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?

Re:Not sure (1)

FauxReal (653820) | more than 6 years ago | (#24865479)

I've seen mineral oil used. In the summer of 94' I went to The Icon Byte Bar and Grill in the SOMA area of SF and they TVs and a computer submerged in mineral oil with the covers taken off sitting in fish tanks. It looked cool and they seemed to work just fine.

P.S. It was also the first internet cafe I went to, they had a "blazing fast" 14.4 SLIP line and I thought this silly black on grey World Wide Web was a waste of time compared to Gopher.

Re:Not sure (5, Informative)

Anti_Climax (447121) | more than 6 years ago | (#24865503)

It is important to keep in mind that light mineral oil like that, while not as bad as other choices, will leech plasticizers out of insulators. The power supply wiring on my machine very quickly became stiff and brittle and it dissolved the soft rubber that was holding the fan assembly to the processor's heat sink. Not sure if it will have any long term effect on the plugs of the electrolytic caps on the board but I wouldn't be surprised.

If you can afford to split the difference between mineral oil and florinert (perfluorocarbon), you might consider a low viscosity silicon oil. That should bu much nicer to natural rubber compounds and plastic insulators.

Re:Not sure (1)

itwasgreektome (785639) | more than 6 years ago | (#24865675)

Water is an extremely poor conductor (ultra pure water is basically non conductive). Everyone forgets that. I've been on the wrong side of the argument before. Technically, if the board didn't release anything into pure water (dust and whatnot), it would remain non-conductive.

Re:Not sure (2, Informative)

maxume (22995) | more than 6 years ago | (#24865793)

Ultra pure water is also a pretty good solvent (which is probably where the problems start to begin).

Re:Not sure (0)

Anonymous Coward | more than 6 years ago | (#24865813)

Water is also an extreamly good solvent. Good luck getting a board that won't have anything water soluble in it.

Re:Not sure (3, Informative)

Anti_Climax (447121) | more than 6 years ago | (#24865439)

From my experience with submersion cooling in mineral oil, if your connectors are submerged they will wick oil up the interior through capillary action. If you build a system similar to that made by Puget Systems [pugetsystems.com] it probably won't be a problem, provided you leave some head space at the top of the case. When I built a system similar to theirs I made a short socket extension for the power cord so it didn't have to go under the fluid. everything else was able to stay above the surface of the oil.

If you submerge your video cards and intend to use the fans as impellers, make sure they can start turning against the resistance of the fluid. All my fans worked when submerged except the video cards.

Solder directly (0)

Weaselmancer (533834) | more than 6 years ago | (#24865559)

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.

A Bad Thing (tm) (4, Insightful)

oni (41625) | more than 6 years ago | (#24865103)

Wouldn't that conduct the heat from the CPU over to the other components?

Re:A Bad Thing (tm) (1)

tmosley (996283) | more than 6 years ago | (#24865177)

A little bit. Most of the heat would spread out into the water or oil through the resin and get conducted away like that.

Theoretically.

Technical Term (4, Informative)

aero6dof (415422) | more than 6 years ago | (#24865113)

The technical term you're looking for is Potting [wikipedia.org] .

Re:Technical Term (3, Funny)

electricbern (1222632) | more than 6 years ago | (#24865155)

How will smoking marijuana help him?

Re:Technical Term (3, Insightful)

oldspewey (1303305) | more than 6 years ago | (#24865289)

Smoking marijuana helps everything

Re:Technical Term (0)

Khyber (864651) | more than 6 years ago | (#24865403)

It helps everything?

Tell that to a person suffering from pneumonia. The LAST thing you want to do is give them something to smoke.

Re:Technical Term (3, Informative)

Facegarden (967477) | more than 6 years ago | (#24865431)

Then give him brownies!
-Taylor

Re:Technical Term (2, Funny)

ReverendLoki (663861) | more than 6 years ago | (#24865453)

Dude, that's what the brownies are for...

Re:Technical Term (1, Funny)

Anonymous Coward | more than 6 years ago | (#24865473)

3: Insightful

Really, is this what we've degraded to? Hurr hurr.

Re:Technical Term (1)

Smoke2Joints (915787) | more than 6 years ago | (#24865703)

do i even need to comment on this?

Re:Technical Term (0)

Anonymous Coward | more than 6 years ago | (#24865533)

Because he will go and watch Buffy instead of dipping his motherboard in polyurethane.

No that's different (4, Informative)

pavon (30274) | more than 6 years ago | (#24865345)

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.

SUN used to do it. (5, Interesting)

UseTheSource (66510) | more than 6 years ago | (#24865121)

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. (1)

ntcleric (1347841) | more than 6 years ago | (#24865253)

I've seen several types of circuit boards similarly lathed in a resinous substance on later model cars. The substance was hard enough to prevent any real tampering of the board without potentially damaging the entire component. I hadn't considered at the time that this was a thermal insulation method, but these boards (being under the hood of a vehicle) would be exposed to higher temperatures than the typical desktop or laptop system.

Re:SUN used to do it. (4, Interesting)

Asmor (775910) | more than 6 years ago | (#24865329)

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.

You should see the IBM version (5, Interesting)

sirwired (27582) | more than 6 years ago | (#24865355)

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. (1, Interesting)

Anonymous Coward | more than 6 years ago | (#24865371)

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. (5, Interesting)

noidentity (188756) | more than 6 years ago | (#24865373)

Someone guy unpotted a Votrax module and refurbished the damaged components [nyud.net] 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.

Re:SUN used to do it. (2, Interesting)

Puzzleer (309198) | more than 6 years ago | (#24865449)

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.

Oil PC going for $140 a barrel (3, Informative)

Anonymous Coward | more than 6 years ago | (#24865151)

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

Something similar is done... (1)

jamieswith (682838) | more than 6 years ago | (#24865207)

...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...

I've done it. (4, Funny)

bigtallmofo (695287) | more than 6 years ago | (#24865225)

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.

Re:I've done it. (0)

Anonymous Coward | more than 6 years ago | (#24865405)

Hey Grandpa Simpson, the 1990s wants its joke back.

Re:I've done it. (3, Funny)

Brett Buck (811747) | more than 6 years ago | (#24865835)

I had an onion on my belt, which was the the style at the time.

        Brett

Check out mineral oil submerged systems.... (1)

teambpsi (307527) | more than 6 years ago | (#24865265)

Do a google search on it, or check out the funky aquarium at:

http://www.pugetsystems.com/submerged.php

you're stupid! (-1, Troll)

Anonymous Coward | more than 6 years ago | (#24865269)

eom

Apollo Program (0)

Anonymous Coward | more than 6 years ago | (#24865291)

NASA did something like this for the computers on the Apollo missions.

Extensibility might be tough. (2, Interesting)

lottameez (816335) | more than 6 years ago | (#24865293)

I'd imagine you'd want to sort out your future memory or disk capacity needs before dipping.

Look into Fluorinert (5, Informative)

grimsnaggle (1320777) | more than 6 years ago | (#24865313)

http://en.wikipedia.org/wiki/Fluorinert [wikipedia.org]

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.

Old skool (0)

srealm (157581) | more than 6 years ago | (#24865339)

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.

Re:Old skool (0)

Anonymous Coward | more than 6 years ago | (#24865435)

You can always try vegetable oil http://www.tomshardware.com/reviews/strip-fans,1203-4.html

Good luck with that (1)

Mishotaki (957104) | more than 6 years ago | (#24865387)

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...

It's common on high-tech boards (3, Interesting)

Anonymous Coward | more than 6 years ago | (#24865409)

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:It's common on high-tech boards (0, Offtopic)

RMB2 (936187) | more than 6 years ago | (#24865423)

... and damn myself for posting that comment as AC. Thought I was logged in....

Try Mineral Oil (4, Funny)

vtcodger (957785) | more than 6 years ago | (#24865413)

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?

Old news (1)

gbrandt (113294) | more than 6 years ago | (#24865443)

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

Re:Old news (3, Informative)

Lisandro (799651) | more than 6 years ago | (#24865579)

Power supplies for the C-64 were 'potted' as were many power supplies of the day.

The original C64 psu was renowed for its poor reilability, which was caused for the poor heat dissipation due to that very epoxy potting. They used big TO-3 transistors which got quite warm during normal operation.

Be aware of (1)

scott792283 (800957) | more than 6 years ago | (#24865467)

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.

My disaster Project (1)

nickswitzer (1352967) | more than 6 years ago | (#24865475)

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.

Obligatory (1)

jameskojiro (705701) | more than 6 years ago | (#24865477)

"You shot my heat sink! Now where am I supposed to sink my f***in heat?"

This is called potting... (2, Insightful)

Lisandro (799651) | more than 6 years ago | (#24865483)

...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.

cockroaches (5, Interesting)

doug (926) | more than 6 years ago | (#24865485)

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:cockroaches (2, Informative)

flyingfsck (986395) | more than 6 years ago | (#24865573)

A bag of moth balls in the equipment would have been cheaper to guard against roach piss.

Re:cockroaches (1)

Bardez (915334) | more than 6 years ago | (#24865779)

You mean Mountain Dew?

(Sorry, people give me shit for drinking it all the time...)

Golden Shellback (0)

Anonymous Coward | more than 6 years ago | (#24865587)

You mean with something like this?: http://golden-shellback.com/ [golden-shellback.com]

Plasti-Dip (1)

Telecommando (513768) | more than 6 years ago | (#24865695)

http://www.plastidip.com/ [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.

That resin may conduct better than somethings (1)

rahvin112 (446269) | more than 6 years ago | (#24865713)

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.

Very old idea (1)

BCMcI (838317) | more than 6 years ago | (#24865729)

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.

Industrial Electronics (4, Informative)

Mike Rice (626857) | more than 6 years ago | (#24865739)

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.

Re:Industrial Electronics (1)

Lisandro (799651) | more than 6 years ago | (#24865829)

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.

I've done this several times to protect printed circuit boards from moisture with great results. I don't know if i'd expect much more from it though.

Characteristic Impedance of High Speed Signals (2, Informative)

gwait (179005) | more than 6 years ago | (#24865809)

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.

The material you want is ... (2, Informative)

mapsjanhere (1130359) | more than 6 years ago | (#24865843)

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.
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