Differential and extrapolation techniques for extracting dielectric loss of printed circuit board laminates

The experiment-based differential and extrapolation techniques to extract frequency-dependent dielectric loss of printed circuit board laminates are proposed. Separation of dielectric loss from conductor loss on substantially rough copper foils is based on the analysis of frequency (ω) components in dielectric and conductor losses. Smooth conductor loss behaves as √ω, while dielectric loss behaves as ω and ω². However, conductor roughness behaves as √ω, ω, and ω², and these contributions may be lumped into the dielectric loss. A few examples of extracting the unique dielectric loss parameters for PCB test striplines with the same dielectric, but with either different types of foils, or with different widths of the signal traces, are presented.