High Thermal Conductivity Materials

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.

Thermal management has become a ‘hot’ field in recent years due to a need to obtain high performance levels in many devices used in such diverse areas as space science, mainframe and desktop computers, optoelectronics and even Formula One racing cars! Thermal solutions require not just taking care of very high thermal flux, but also ‘hot spots’, where the flux densities can exceed 200 W/cm².

High thermal conductivity materials play an important role in addressing thermal management issues. This volume provides readers a basic understanding of the thermal conduction mechanisms in these materials and discusses how the thermal conductivity may be related to their crystal structures as well as microstructures developed as a result of their processing history. The techniques for accurate measurement of these properties on large as well as small scales have been reviewed. Detailed information on the thermal conductivity of diverse materials including aluminum nitride (AlN), silicon carbide (SiC), diamond, as well as carbon nanotubes has been presented. The emphasis is on developing basic understanding of the inter-relationships between thermal conductivity and processing such that the readers can conduct their own research in this exciting field of high thermal conductivity materials. Engineers and scientists involved in addressing thermal management issues in a broad spectrum of industries should find this book a valuable resource in their work.