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

ID 683624
Date 1/29/2020

1.1. PCB Material Selection

The printed circuit board (PCB) material is the substrate upon which the channel design is constructed. It consists of the core, prepreg dielectric layers, and copper foils stacked and glued together to from the complete PCB stack-up. The dielectric and copper layers form the reference planes and routing layers for the channel design. The sources of signal attenuation resulting from the PCB material include dielectric loss, conductor loss, reflections due to mismatched impedance, and radiation loss. Losses due to radiation are usually very small and can be ignored. The remaining losses can be attributed to the various properties of the material choice. Material properties that directly affect the link performance include:

  • Loss tangent (tan(δ)/Df)
  • Dielectric constant (Er/Dk)
  • Fiberglass weave composition
  • Copper surface roughness