Thermal Spreading and Contact Resistance

8Applications with Nonuniform Conductance in the Sink Plane

Thermal spreading resistance in finite systems such as heat sinks is often modeled using a uniform conductance in the sink plane. In regards to heat sinks containing fins, this requires that the distribution of fins is both uniform in spacing and height and cooled with a constant convection heat transfer coefficient. In many real applications, this is not achieved due to nonuniform fin heights/spacings and the nature of the supplied cooling using fans. In impingement air cooling applications, the local heat transfer coefficient is always distributed over the surface.

For example Figure 8.1a illustrates the nonuniform distribution of pin fins in a CPU cooling device, while Figure ...