Improved Expression for the Via-Plate Capacitance Based on the Magnetic-Frill Model

In the recent years, several methods for the calculation of the via-plate capacitance in multilayer printed circuit boards have been developed. A widely used analytical approach is the application of a magnetic-frill current as an equivalent TEM excitation within the antipad. Recently, the comparison of the corresponding capacitance expression with an exact static analytical solution and with numerical simulations has shown some discrepancies, especially for large pads. In this letter, the cause for the error is found to be an inconsistent admittance definition. Based on an alternative complex-power approach, a novel capacitance expression is developed which agrees quite well with reference data.