Steady-State and Transient Electro-Thermal Simulation of Power Devices and Circuits Based on a Fully Physical Thermal Model

An original approach is presented to the timedependent thermal modelling of complex 3-dimensional electronic systems, from metallised power FETs and MMICs, though MCMs, up to circuit board level. This method o ers a powerful alternative to conventional numerical thermal simulation techniques. In contrast to semi-analytical Fourier approaches involving DFT-FFT, the method is based on explicit, fully analytical, double Fourier series expressions for thermal subsystem solutions in complex frequency space. It goes beyond previous rectangular multilayer solutions by treating complex geometries, and providing a full description of thermal material non linearities as well as explicit inclusion of surface uxes. It provides a fully physical, and near exact, generalised multiport network parameter description of distributed thermal subsystems. In contrast to existing circuit level approaches, it requires no reduced model RCnetwork approximation for fully coupled, electro-thermal CAD. Implementation of the thermal model as N-port elements within a circuit simulation engine, Transim, is described and illustrative simulation results presented.