This paper presents a full partial equivalent electrical circuit (PEEC) model of an electromagnetic compatibility (EMC) filter, including the discrete components as well as the interconnection models. Therefore, the complete behavior of the filter is taken into account, including all magnetic stray elements (inductance and couplings). This model is validated for several configurations. It is then used in an optimization process, allowing the determination of the optimal geometry for the printed circuit board tracks, to obtain the best possible performance of the EMC filter. Both numerical implantation and full analytical study are used in this study.