Effective roughness dielectric in a PCB: Measurement and full-wave simulation verification

Surface roughness topography of printed circuit boards (PCBs) needs to be included in SI simulations in order to accurately predict the insertion loss of the structure. An effective roughness dielectric (ERD) model can be used to substitute an inhomogeneous interface between copper foil and laminate dielectric in a PCB. Herein, this approach is tested for verification using 3D full-wave numerical simulations. These effective roughness dielectric layers with the appropriate complex permittivity are included in the modeling of stripline examples. The parameters of an ambient laminate dielectric free of conductor roughness effects in the stripline are determined using differential extrapolation roughness measurement teachnique (DERM). The agreement of the results of 3D full-wave modeling simulations with the proposed approach and measurements justifies the proposed approach.