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IBM chip cooling breakthrough


Secrets hidden in glue


As computer chips are growing in power, more efficient cooling has to be applied. At the time being, the only "solution" to this problem is mounting a better cooler on the chip. The problem is that these coolers are the second stage of cooling, and chip cooling effectiveness lies in the first stage which has proven to be a weak chain.




Schematics of the complete chip cooling (with mounted cooler)


At the IBM Zurich Research Laboratory, scientists have found that heat transferring efficiency can be dramatically increased if the heat transfer inside the chip is redesigned. As you all may know, the chip consists of a microprocessor and a cooling system. To connect these two systems to one, glue is used. To improve glues heat conducting properties, it is enriched with metal or ceramic particles. And here comes the main problem. A glue is a fluid.



As you may see, heat conducting particles are not spreading evenly in all directions 


The mixture of glue and the heat conductive particles form a homogeneous fluid, but as you may know fluids have different physical properties at different temperatures. When the mixture is applied to the microprocessor the cooling system is put on top of it. Mechanical energy is used to squeeze these two elements as near as possible. As we said, glue is a fluid, and during the binding process id flows between these two elements filling all the gaps. Problem that arises here is that the mixture loses its homogeneous structure while the pressure and temperature rise. The heat conductive particles are not forming a thin film, as they should. IBMs scientists have found that these particles tend to pile up, leaving some areas "without cooling".



Micro channels look like irrigation channels - they should help in forming a thin and homogeneous layer of glue. 


The solution to this problem is to "help" the fluid (glue) to spread over the microprocessor evenly, forming a perfect thin and homogeneous layer. Micrometer sized channels are going to be added to the cooling system plate on the side facing the microprocessor. These channels are going to act like irrigation channels, helping to transfer heat conductive particles from "choking points" where they piled up to spots where their concentration is below the need one.

The system will allow chip makers to use to three times less glue with the reduction of thermal resistance by the factor of three.
Last modified on 28 March 2007
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