10.1 Introduction

Heat is an unavoidable by-product of every electronic device and circuit,1 and it needs to be minimized to improve reliability and maximize electrical performance. Managing this heat, commonly referred to as thermal management, requires an understanding of thermodynamics and an in-depth knowledge of the materials.

This chapter, which provides both an introduction into thermal management of electronic packaging and descriptions of the various materials used, is intended not only for thermal management experts but also for those in related fields who have a need to model and optimize their physical designs.

The trend in electronic packaging has been to reduce size and increase performance. This can be seen in the higher levels of integration in semiconductors and the increased usage of hybrids and multichip modules (MCMs). Intel s first microprocessor, the 4004, had 2,300 transistors. The latest microprocessor, the Pentium 4 ^[*], has 42 million transistors.2 Placing more functions in a smaller package has resulted in higher heat densities, which mandate that thermal management be given a high priority in design so as to maintain system performance and reliability. As clock rates increase every year, the power dissipated in the semiconductors during switching is increasing at a linear rate, proportional to frequency as shown by the following equation:

(10.1)

where C = input capacitance in farads

V = peak-to-peak voltage swing of signal in volts

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