Thermal Processes in Electronic Equipment at Uncertainty

Abstract

At present, electronic systems are thermally designed on the basis of the assumption that all the parameters and factors that determine the thermal processes are fully known and unambiguously determined, id est, that they are determinate. However, the practice of creation and operation of real electronic systems shows that the real values of determining parameters and factors, as well as the thermal processes and temperature distributions, are uncertain and can take any values within some intervals of their variation with an equal probability. The disregard for the interval stochastic character of the thermal processes leads to design errors and development of uncompetitive electronic systems. This article elaborates a method that permits modeling non-stationary interval stochastic thermal processes in an electronic system at interval uncertainty of input factors and parameters. The method is based on obtaining equations for non-stationary statistical measures (mathematical expectations, variances, mean square deviations, and covariances) of thermal processes at specified statistical measures of input data. The article gives an example of applying the elaborated method to thermal processes in a real electronic system that consists of electronic modules with printed circuit boards, as well as integrated microcircuits, resistors, and other electronic components installed on them.