Cooling of ICs

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Summary: A miniature heat sink containing microchannels for extremely effective forced air cooling of high power electronic devices. Multiple vortex rings are generated and propagate along the channels. This causes optimum mixing of the air which leads to enhanced heat removal from the hot device. Due to the small size of the microchannel, a large number of such channels can be placed over a given heat generating surface in a single layer or multiple layers (the thickness of a layer is less than 1mm) to yield a very high heat removal rate within a very small size heat sink. The channels can also be integrated as separate layers in a 3-D electronic circuit architectures, located between layers of heat generating components to effectively remove heat and resolve hot-spot regions.   Potential Applications The global market for Electronic Thermal Management is forecast to reach $8.6 billion by 2015, Factors driving growth include developments in technology and a marked increase in the production of miniaturized microprocessors. However, the more dense integrated circuits become, the more heat removal becomes a problem, since the same (or better) processing power is packed into a smaller package. It is necessary to remove this heat as effectively as possible, preferably using air (rather than cooling fluids). Usually, efficient heat removal in the miniature scale (sub-mm) is difficult since convection is relatively weak. The discovery of microchannels as effective vortex rings generators and their implementation in a miniaturized heat sink is a potential enableer to continued miniaturization. To overcome this difficulty, liquids with high heat capacity are used. However, air is preferable. The present invention augments heat removal rate using air by generating compressible vortex rings across a small orifice (~200micron diameter) in microchannels (~300micron diameter). This set up generates a train of vortex rings that enhances heat removal significantly (2-4 times an equivalent straight channel flow). Possible applications are in the electronics cooling industry, including cooling of existing CPU as well as new generation of 3-D electronic circuit architectures. In the later case, the air microchannels can be integrated into the chip.   Advantages of the Invention air-based heat sinks reach ~2Watt/cm2 in significantly larger dimensions. Since this is insufficient cooling capacity in high density ICs, liquids with high heat capacity are used which is expensive and cumbersome, necessitating a sealed flow system and multiple heat exchangers. Our devices can have heat removal rates of 5Watt/cm2 and beyond. Thus, the the following benefits are achieved over liquid cooling. : (i) air as the cooling substance, (ii) sub-mm size, (iii) heat removal capability better than existing air-based heat sinks, (iv) at least one order of magnitude less volume.