On 9/9/05, Jack Carroll <[EMAIL PROTECTED]> wrote: > > Dunno what to tell you. We could probably figure out something, and > bench-test it to prove that it cools the chips. If we were to put a > centrifugal blower outside the cramped area, and use flat ductwork to carry > the air to the heat sink, it would probably have to be some kind of > cut-to-fit ductwork that could be easily configured in the field to fit > where it has to go. Another possibility might be a heat sink with cooling > pins instead of fins, and increase its area to get the volume up even with > limited thickness. That might work with natural convection flow in any > direction, if the total heat load isn't too large. There still has to be a > way for air to get in and out of the area, though, or nothing will work. > I've done some of this kind of design, but only in well-understood > industrial situations. I'm no expert on forced-air cooling, and I don't > know the component suppliers for blowers that can run from motherboard fan > headers. Maybe Aavid or Wakefield Engineering has some application notes or > tutorials that could educate us. I can at least look. > If this threatens to become a big deal, we might want to mount an > analog temperature IC on the heat sink, so the developer can tell what's > really happening. There are some that can be read out with a common > hand-held voltmeter. I could look in a couple of catalogs if you want me > to. > I'm so thankful I picked the builder of my big dual Athlon machine > for their expertise in airflow. > I guess the thing that has to be done fairly soon, before parts > placement can get under way, is decide the space envelope allocated to the > on-board heat sink, and the method of attachment and conductive heat > transfer. Screw holes may have to be placed in the board for heat sink > mounting, and their sizes, locations, and keep-out zones must be included in > the dimension drawing at start of design. Don't forget to analyze the > tolerance stack-ups around the holes, and make the keep-out zones large > enough to contain screw heads, lock washers, and spacers at maximum > misalignment plus .015" clearance to the nearest live copper. I always > connect mounting hole pads to the ground plane.
I'll talk to Howard further on this. Tech Source has used some centrifugal fans on their longer medical cards, but for OGD, we would like to have a shorter card, if possible. Let's focus on passive cooling for the moment. _______________________________________________ Open-graphics mailing list [email protected] http://lists.duskglow.com/mailman/listinfo/open-graphics List service provided by Duskglow Consulting, LLC (www.duskglow.com)
