A straightforward analytical method for extraction of semiconductor device transient thermal parameters

Most of the thermal characterization of packaged semiconductor devices is carried out in the time domain by measuring and recording the values of a temperature sensitive electrical parameter (TSEP) as a function of time, during the heating or cooling transient caused by the application of a given power function, generally a step, to the device. Although this time response contains, within measurement resolution, all the relevant information about device thermal behaviour, the “packed” form of this information is not so convenient for its immediate use when we want to obtain a thermal model for further simulation or extract some information on device structure. Real and imaginary parts of device frequency response are a better way of dealing with measurement results because its “unpacked” form leads easily to thermal model and structural information.In this paper we derive a direct analytical calculation of the frequency response from the scalar time domain response as well as an approximate method to obtain an equivalent thermal model.