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The Challenging Task of Thermal Management

The constant increase of power densities inside of power electronic components is an omnipresent trend that in future is going to continue. One of the consequences related to this trend is a constant increase of junction temperatures in power electronic devices. With this, the thermal management becomes a more important design criteria. The present paper deals with several aspects of thermal management, focusing on the often neglected influence of building a proper interface between power module and heat sink. Measured data of an ongoing research is presented concentrating on applying and testing adequate thermal interface materials. From the first days of IGBT-Module technology to the present, chip sizes for a given current carrying capability of silicon have constantly been decreased. Vice versa, the current density inside the silicon die and therefore the power modules has grown. Smaller chips also allowed the integration of more silicon into one device, often doubling the current a given housing could handle. Though the losses per amp in every new chip generation have also decreased, the higher power densities lead to increased junction temperatures as well. The beneficial increase in performance is often wasted by underestimating the thermal design. From this point of view it becomes obvious, that the thermal transfer from the chip’s junction to the ambient gets more important.

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936.80 KB
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31/05/2011