Cooling hot chips

[mecheng66]

I'm trying to figure out how to cool a circuit board with a lot of hot chips. We can supply pretty good airflow so I think the main thing is sizing heat sinks to see if it's feasible.

After wading through heat sink catalogs I think we may need a custom design. I can find lots of info on heat sink design but I wonder if anyone on this forum can recommend the best set of formulas or tools for this? I'd like to try a CFD program but we just don't have the budget...

 

[IRstuff]

Heat sinks put in after the fact tend to be marginal. For the military, the traditional approach was the metal core board. Since the die has better thermal path to the bottom, a thermal path from the bottom may be better.

TTFN

 

[ko99]

Thanks for the replies.

Randeep, you hit on one of the problems I'm having. The heat sink performance curves are based on tests with different heat source sizes, so I'm not sure how they'll really perform. The hottest chip is a 40W FCBGA with an 11 x 8 mm die on top.

The board itself is about 250 x 300 mm with about 35mm above for heat sinks or whatever. There's plenty of room for fans to supply good airflow entering across the board.

IRstuff, most of the chips have a better thermal path to the top, not the board.

ko (

http://www.ecooling.biz)

 

[ko99]

Sorry mecheng66, I meant to respond to your question but your problem sounds just like one I'm working on and I went off on a tangent...

Some links that might help you:
Heat spreading:

http://www.electronics-cooling.com/html/2004_may_cc.html

Heat sink design:

http://www.biberthermal.com/Reference_Links/Publications_List/isps99paper.pdf

http://www.electronics-cooling.com/Resources/EC_Articles/JUN95/jun95_01.htm

ko (

http://www.ecooling.biz)

 

[zdas04]

You might look at thread391-115515 for a discussion of Ranke Hilche Vortex Tubes. Since you have "plenty of air" it might be a tool to help your problem.

David