Compact electro-thermal models of semiconductor devices with multiple heat sources

The thermal management of semiconductor devices and systems becomes crucial as the power consumed by chips is increasing. For manufacturers it is important to enable the customer to simulate the thermal performance of semiconductor packages at different ambient conditions and arbitrary transient loading conditions. As simulation speed in this case is crucial, compact thermal models are of great importance. In the present work, a new approach to generate compact thermal models of semiconductor packages on PCBs is presented. The main difference from conventional RC-like thermal networks is that the compact model is obtained through a formal model reduction procedure. Model reduction starts with an accurate high-dimensional thermal model created with a finite element program like ANSYS. A low-dimensional model is obtained in such a way that the first moments of the transfer function are the same as in the original model. A model of a semiconductor device with multiple heat sources is used in order to compare this method with a thermal RC network approach. Temperature response results to user defined loading conditions are also compared.