AN 672: Transceiver Link Design Guidelines for High-Gbps Data Rate Transmission

ID 683624
Date 1/29/2020

1.4.1. PCB Material Selection

  • Select the material with the lower loss tangent to reduce signal attenuation from dielectric losses.
  • Always choose lower Ɛr with a flat frequency response for best signal performance and to reduce signal dispersion that adds phase jitter.
  • Always choose more densely woven fiberglass style for the core and prepreg material surrounding the high speed signal layers for more uniform Ɛr that minimizes impedance and signal velocity variations.
  • Choose sparsely dense fiberglass styles for power layers and slower general purpose signal layers to reduce PCB cost.
  • Use wider traces and choose rolled copper foils over traditional electrodeposited (ED) copper foils in the PCB construction to mitigate conductor loss.
  • Certain simulation tools may not include loss effects from surface roughness. In these cases, the correction factor (KSR) must be added to get realistic prediction of the actual loss.