Fiber weave impact on crosstalk of high speed communication channels in glass epoxy packages

Some packaging technologies utilize glass epoxy substrates that are composed of glass fiber bundles and epoxy resin. Because of the different electrical properties of glass and resin, the signal traces can have some variability, depending on their position with respect to the weaves. One of the parameters that are affected by the inhomogeneity of the substrate is the far end crosstalk. Crosstalk may significantly increase, hindering the link budget of high speed communication channels, especially in the dense routing areas. This paper addresses the crosstalk variations, in the frequency and time domains, due to the fiber weave effect (FWE). Analytical and numerical results are presented to provide a physical insight into the phenomenon, followed by a mitigation technique to minimize the impact.