Thermal compact models: an alternative approach

Thermal compact models enable the prediction of junction temperatures of complicated components in a system level numerical simulation with a minimum of computational effort. A method for generating compact models has been proposed by the DELPHI consortium. Here a new approach is proposed that is no longer based on a statistical treatment using optimization but on analyzing the heat flux distributions that occur. Using this new approach a new method for generating compact models is suggested, which obtains models that are, in principle, equal to the models found using the DELPHI approach, but at virtually no computational effort. The analysis puts compact models on a firm mathematical and physical basis and proves that no linear model with a limited number of nodes can ever be truly boundary condition independent. Furthermore, it is shown that the shape of the distribution function of the heat flux over the external surfaces of the component determines both the number of nodes needed in the compact model and its accuracy.