A Cross-sectional Profile Based Model for Stripline Conductor Surface Roughness

As the data rate of high-speed digital systems is getting higher, the conductor loss can no more be modeled assuming perfectly smooth conductor surfaces for even the smoothest foils available. The Huray model, based on the analytical calculation of the additional loss due to the scattering/absorption from conductive spheres on a smooth plane, has been presented to account for this issue. However, in practice it is very difficult to determine the parameters of the model. A modeling approach relating the parameters of the model to the conductor roughness profiles is needed. In this paper an investigation of the scattering by metal hemispheres, including their interaction, is performed. A method is brought up to estimate the multi-level physical model's parameters using the scanning electron microscope (SEM) or optical cross-sectional profile imaging. Accurate modeling of the frequency-dependent conductor loss is achieved.