Thermal management has always been a major concern in the design of high frequency, high power electronic devices. For example, historically, in many power amplifier designs, the vast majority of the power that needs to be dissipated is from the high power field effect transistors, or FET's, themselves. In these cases, the high power dissipation often requires direct attachment of the FET's to a heat sink of some type. Heat sinks have become almost essential to modern central processing units and other electronic devices.
Ideally, heat sinks are made from a good thermal conductor such as silver, gold, copper or aluminum alloy. Copper and aluminum are among the most frequently used materials for this purpose with electronic devices. In addition, recently, synthetic diamond cooling sinks have been developed to provide better cooling. Further, some heat sinks are constructed of more than one material with desirable features, such as phase change materials. Such materials can store a great deal of energy due to their heat of fusion. However, while many of these materials provide heat sink features, they do not address other needs of the device, such as electrical insulation. This article will highlight those needs and how new materials deal with those requirements.
Before discussing new developments in materials for thermal management, an overview of...