Resumen de Experimental investigation of discrete air cooled device thermal resistance dependence on cooling conditions
Marcin Janicki, Tomasz Torzewicz, Agnieszka Samson, Tomasz Raszkowski, Artur Sobczak, Mariusz Zubert, Andrzej K. T. Napieralski
Abstract Temperature is an important factor influencing the operation of electronic devices, thus adequate thermal models should be used for their accurate simulations. Unfortunately, the information on device thermal characteristics provided by their manufacturers is very scarce and usually it is limited only to the specification of the junction-to-case thermal resistance, which is not sufficient for the prediction of device dynamic thermal behaviour. This problem is discussed here based on the practical example of an air cooled power device operating at different power dissipation levels and in variable cooling conditions. The experiments presented in this paper demonstrate that the notion of junction-to-case thermal resistance is ambiguous since the cooling conditions affect the heat diffusion processes inside the package and consequently influence the thermal resistance value. For the analysed device, a simple four-stage RC Foster ladder model is proposed here to simulate the device dynamic thermal behaviour. Owing to the fact that this model is generated in a structure preserving way, its element values can be assigned some physical meaning.
