An improved two-resistors compact thermal model by means of modified top-surface-area

The concept of Compact Thermal Model predicts die temperatures to a high level of accuracy depending on the complexity of the network and on the number of resistors. Unfortunately, complex CTMs still are not completely available to end-users. The simplest CTM is a two-resistor model with junction-to-board and junction-to-top as thermal resistors (/spl theta//sub jb/ and /spl theta//sub jt/ respectively). At the present time, this model appears to be the most popular and applicable CTM among the end-users community. Despite the simplicity of this model it reasonably predicts die temperatures. Typical errors are within 30% for convection applications. Nevertheless, when accurate temperature predictions are required, errors higher than 10% may be sometimes considered as too high. In this paper, an expanded approach is suggested for the application of a two-resistors model. The main idea of this method is to take into account approximately the top-surface temperature profile of the IC package by means of Modified Top-Surface-Area. This MTSA approach was tested against results taken from the literature. It appears to produce typical errors to within 10% for many common engineering applications.