A Method to Determine Dielectric Model Parameters for Broadband Permittivity Characterization of Thin Film Substrates

This article introduces an efficient method to determine the dielectric model parameters of a thin film substrate from microstrip line measurements and electromagnetic analysis. The proposed method avoids using optimization algorithms which normally require extensive computation time. The complex permittivity is extracted through only one full-wave simulation. The multipole Debye model was employed to fit the extracted complex permittivity. The parameters of the best-fitting model obtained through this procedure are considered as the final results, which also ensure physically consistent characteristics. Polyimide was selected to validate the methodology. The best-fitting model generated by the proposed method has shown excellent agreement to the polyimide data sheet values at 1 MHz. Moreover, simulations using the parameters of the best-fitting model exhibit good agreement with the experimental propagation constant data of microstrip lines up to 60 GHz.