Dielectric Characterization of Printed Circuit Board by Microstrip Line Up to 110 GHz

Abstract

This paper presents the characterization method and the measurement result of the dielectric property for printed circuit boards (PCBs) by microstrip transmission lines (TLs), with the multiline thru-reflect-line (MTRL) calibration and the probing techniques for the scattering parameter (S-parameter) measurements. The broadband TL propagation constant is evaluated accurately after the MTRL calibration, and the characteristic impedance is further determined by an additional resistor test item with the low substrate loss assumption. The extraction of the dielectric constant (DK) for the PCB substrate then becomes an inverse problem where the estimated DK can determine the TL propagation constant which is compared to the measured data for modifying the DK; this process is proceeded iteratively until the error between calculated value and the measured one satisfying the criterion. The proposed method is examined by the NF30 substrate, in the frequency range from 1 GHz to 110 GHz.