Modeling and Mitigating Fiber Weave Effect Using Layer Equivalent Model and Monte Carlo Method

Abstract

Nowadays, glass fiber and resin are very common dielectric substrate in PCB. With the increasing data rates, fiber weave effect will cause severe signal integrity issue. This paper introduces the influence on transmission line characteristics due to fiber weave effect, and proposes a layer equivalent model with layer equivalent dielectric constant $\varepsilon _r^\prime $ for fast calculation of effective dielectric constant ε <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">eff</inf> and the associated timing skew. According to this model, Monte Carlo method is used to quickly analyze the relationship between layer equivalent dielectric constant and slant transmission line without resorting to three-dimensional electromagnetic simulation. The appropriate slant angle to mitigate fiber weave effect is investigated and the optimum zig-zag routing design is derived.