Rigorous model and network for transient thermal problems

A compact thermal model is presented for the transient hot spot (junction) temperatures and contact heat flow development of electronic systems with multiple thermal ports. The purpose of this paper is (1) to extend the previously developed steady state model to different representations thus providing the relations between the model descriptions of different working groups, and (2) to establish a general time dependent compact model and network, making use of the superposition principle. The transient model is constructed by using thermal impedances in the time and frequency domain. A corresponding network with thermal resistors and capacitors is established. The model is exact provided that the heat conduction equation is linear and the temperature distribution along the thermal contact areas is uniform.