Experiment-Based Separation of Conductor Loss from Dielectric Loss in PCB Striplines

High-speed digital design and signal integrity (SI) engineers need accurate characterization of commercially available printed circuit board (PCB) materials, since this is important for providing technical characteristics of designs and reducing cost-to-quality ratio. PCBs are known to have a substantial level of copper foil roughness. If the roughness effects upon signal propagation are neglected or underestimated, especially at GHz operating frequencies, the dielectric properties extracted with transmission line methods might be misleading and result in significant errors in designs from SI point of view. An experiment-based method to extract frequency-dependent dielectric properties of PCB laminates and separate rough conductor loss from dielectric loss on PCBs with substantial levels of copper foil roughness is proposed. This method is based on the analysis of frequency (ω) components in losses behaving as √ω, ω, and ω2.