Prof Gilbert de Mey from the University of Ghent in Belgium recently visited WIT and presented a seminar entitled ‘Thermal Impedance Simulation of Electronic Packages’.

The seminar discussed the thermal impedance simulation of electronic packages. If the thermal impedance of an electronic package is measured experimentally there are of course several ways to represent the results graphically. If a Nyquist plot is used, i.e. the imaginary part versus the real part using the frequency as a parameter, it was observed that the curve was always composed of a limited number of circular arcs. This is a very remarkable observation which requires a theoretical explanation. A boundary element method has been established to solve the heat diffusion equation in AC (phasor notation) for arbitrary block shaped structures, normally used for packing electronic chips. Several structures have been analysed and the numerical results always provided Nyquist plots consisting of a few circular arcs, in full accordance with experimental results. The lecture was well attended and generated a great deal of interest from the participants.