The influence of heat sink on noise susceptibility of IC

This study discusses the influence of a heat sink (in the case that a heat sink is a plain conductor) on noise susceptibility of an IC. Paying attention to the capacitive coupling between adjacent PCBs (printed circuit boards), the equivalent model of capacitive coupling in the case of the existence of a heat sink is proposed. The induced noise voltage on an IC lead is predicted by applying the finite element method to the prediction of the capacitance between a noise source and a heat sink, and the predicted results are compared with the measured results. It is concluded that prediction method is practically useful below the 100 MHz, as the predicted results coincide with measured results within 2 dB below 50 MHz and within 5 dB below 90 MHz