Authors: Y.C. Gerstenmaier, H. Pape and G. Wachutka
Affilation: Siemens AG, Corporate Technology, Germany
Pages: 84 - 87
Keywords: compact thermal model, boundary condition independence, thermal resistor networks, electronic packages.
A compact thermal model is presented, which describes the hot spot (junction) temperatures and contact heat flows of electronic packages or systems in the stationary state. The model is exact provided that the underlying heat conduction equation is linear (i.e. no temperature dependence of thermal conductivities is assumed) and the thermal contact areas to the environment have uniform temperature distribution. The model leads to a systematic method to construct thermal resistor networks. The number of model parameters for n contact areas and m independent heat sources is o (n-1) (n + 4 m) + m 2. They are determined by successive linear fits to simulated and measured temperatures and heat flows of the system. The method is demonstrated by application to IC packages and compared to a description with seven-resistor networks. The accuracy is improved considerably, however at the expense of an increase of the number of model parameters to 26 for a package with 6 thermal contact areas.