Thermal interface resistance is a measure of how well
heat is transferred across the interface of two mating rigid
surfaces, such as a CPU and a heat sink baseplate
In the case of the CPU–heat sink interface (the focus of
the present work), the interface resistance (per unit area) iswhere T
cpu is the CPU (or other electronic package) surface
temperature, Ths is the heat sink baseplate temperature, Q00 is
the power per unit area of the heat-emitting component. The
Rint is commonly presented with units of K cm2/W (or
K in.2/W). As can be seen in the equation for Rint, the lowest
possible interface resistance is reached when the heat sink
temperature approaches that of the CPU.