ABSTRACT
So far the Fourier’s law of heat conduction, first introduced in Chapter 4, Section 4.1, has been used to calculate conduction heat transfer rate in a medium. This approach is reasonably accurate, and provides good first-order engineering approximations, in cases where heat conduction is mainly one-dimensional and there is no heat generation in the medium. Conduction heat transfer through the length of a thin fin, in the base of a heat sink that is the same size as the electronic device it is mounted on, and through the interface material inserted between a heat sink and an electronic package are examples in which this approach is reasonably accurate. However, there are other situations that either one-dimensional heat conduction assumption is not valid or there is heat generation in the medium. Conduction heat transfer in a heat spreader attached to a much smaller die, inside a foil heater with electrical joule heating, and in a printed circuit board are examples in which this simple approach will give erroneous results.
