Need help with cooling a >small< project

T

tom61

[H]ard|Gawd
Joined
Feb 3, 2001
Messages
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I'm building a handheld PC, not unlike a UMPC/Origami. However, as the board sits on my desk, it has cooling issues with the video chip. Part of the trouble, at least I think so, is solvable with having the board vertically, as the system RAM is currently underneath the video chip.

Pictures (5MPixel):
http://tom61.arcadecontrols.com/pics/ebcboard.jpg
http://tom61.arcadecontrols.com/pics/ebcports.jpg

Worklog for the project:
http://www.hardforum.com/showthread.php?t=892708&page=7&pp=20 (scroll down to post #137, as that is when I switched the project to this board)

The board is about the size of a floppy drive, and would fit in a 3.5" bay if the ports didn't stick out. The plans are to at least semi-enclose the board with the screen and controls.

Any ideas for cooling a board like this in a small space? (likely around 5x5x2 to 6x7x2 inches) Also, keep in mind that this needs to run off batteries.
 
Imagine a rectangular copper plate the size of the board, lying on top of it (maybe 2.5 - 3mm plate).

Each component you want cooled, has a copper shim connecting it to the plate. I.e, you'd measure the height of the component to calculate the thickness of its shim. Make the shim as broad as possible, for maximum contact area with the plate.

From your electronics supplier, get a bunch of finely finned aluminum heatsinks (or raid your local Slot A Athlon heatsink warehouse :D). These get bolted to the outside of the plate. Secure the shims in their proper locations to the plate, either using countersunk bolts or thermal epoxy, whatever is more appropriate.

The whole lot gets bolted to the board, using thermal goo for the shims and components.

If you have enough outside surface area, it should be enough to cool the whole thing passively, even the CPU. Ideally, of course, the board should be standing upright, with the fins of the heatsinks running vertically, to allow convection to do the most good.

If you have access to CNC facilities, you could design and fabricate the whole thing in one piece, including, perhaps, a housing or attachment points for your display. Aluminium would make it lighter and more cost effective, as you no doubt know already. You might still need coppy for the shims, I'd reckon.

Give the whole thing a LIGHT coat of black spraypaint, in order to increase its rate of heat radiation, and to keep tarnishing at bay.
 
Yup. If it's going to be passive cooled by convection and radiation, then black is what you need. But it has to be as thin a coat as possible, obviously, or the paint itself will act as an insulator.
 
Interesting idea with the shims. I wanted to put a heatsink over the whole thing, but with all the capacitors, condensers, jumpers, etc. sticking up, I figured it wouldn't be practical. Still not easy to do, as it'd require quite a bit of precision measurement and manufacturing, and to be remotely small, would still have to have holes drilled for capacitors and condensers.

If I go this route, I might rip the old heatsink out of my I-Opener. It has a nice, fairly large, not very thick, black passive heatsink.

Other ideas? Simpler the better, of course.

Just checking out a [H]ard option, anyone know of a very small (like 1"x6"x1") water radiator?
 
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