Account of the package features in modelling of thermal microsensors

This paper presents the procedure for taking into account the packaging features in the analytical modelling of thermal microsensors. The case of sensor mounted in the standard packaging is considered. In such configuration, the active domain in which basic thermal processes take place is marked out. This domain includes the thermally isolated structure and the air gaps above and below this structure. It is substituted by the equivalent domain which is divided into some rectangular regions with homogeneous parameters. The temperature distribution in these regions is obtained using the Fourier method. The parameters characterising thermal conduction processes between adjacent regions are found using adjoint boundary conditions. Based on the presented model the temperature distribution in the chosen thermal microsensor was calculated and the dependence of the hot thermopile junctions temperature on the air gap between the top surface of the sensor structure and housing cover was determined. The dependencies of the heat flows in the structure of the thermal microsensor on the size of the air gap were also studied.