Thermal Management Heat Sink Applications

Because of its high thermal conductivity, diamond is an excellent heatsink material, mostly for hIgh-density electronic circuits. Athin slice, in size up to 3 X 3 X1 mm, is cut from a natural crystal, metallized by sputtering a gold alloy and soldered to a copper base. A typical diamond heat-sink configuration is shown in Fig. 12.12.  

The drawbacks of these single-crystal diamond heat sinks are the presence of metallic impurities and size limitations. CVD diamond, which does not have these drawbacks, is a competitor which may eventually replace the single-crystal material (see Ch. 13). 

Natural diamond is used almost exclusively for applications requiring h8df a carat or more such as heat sinks, optical windows, knives, and others described below. Such applications form a small but steadily growing market although, here again, the possibility of being replaced by CVD diamond should not be overlooked. 

Optical Applications. Although diamond can be considered as the ideal optical material, it has found little applications in optics so far because of its restricted size and high cost. It has been used by NASA as an optical window for the Pioneer Venus spacecraft, clearly a case where cost is secondary to performance.P J 

Mechanical Applications. Anvils made of single-crystal natural diamond can generate extremely high pressures, up to 4.6 Mbar (a pressure significantly higher than the pressure at the center of the earth). Typical anvil shapes are shown in Fig. 

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Several applications such as lasers. X-ray medical systems, avionics, and computer data centers require dissipation of a large amount of heats from small areas. Two-phase cooling schemes are one of the actively pursued high heat flux thermal management systems. It has many unique attributes, that is, high heat dissipation-to-volume ratio, small coolant inventory, relative ease of fabrication, and compactness. Various experimental results have been reported to understand the heat transfer phenomena and develop appropriate correlations for accounting various features unique to microchannel heat sinks. 

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