Thedemandfore?cientthermalmanagementhasincreasedsubstantiallyover the last decade in every imaginable area, be it a formula 1 racing car suddenly braking to decelerate from 200 to 50 mph going around a sharp corner, a space shuttle entering the earth’s atmosphere, or an advanced microproc- sor operating at a very high speed. The temperatures at the hot junctions are extremely high and the thermal ?ux can reach values higher than a few 2 hundred to a thousand watts/cm in these applications. To take a speci?c example of the microelectronics area, the chip heat ?ux for CMOS microp- cessors, though moderate compared to the numbers mentioned above have 2 already reached values close to 100 W/cm , and are projected to increase 2 above 200 W/cm over the next few years. Although the thermal mana- ment strategies for microprocessors do involve power optimization through improved design, it is extremely di?cult to eliminate “hot spots” completely. This is where high thermal conductivity materials ?nd most of their appli- tions, as “heat spreaders”. The high thermal conductivity of these materials allows the heat to be carried away from the “hot spots” very quickly in all directions thereby “spreading” the heat. Heat spreading reduces the heat ?ux density, and thus makes it possible to cool systems using standard cooling solutions like ?nned heat sinks with forced air cooling.
