Three-dimensional viscoelastic simulation of woven composite substrates for multilayer circuit boards

Viscoelastic properties of woven composite substrates are essential to design dimensionally stable multilayer printed circuit boards. Unlike most existing numerical work which rely on simplified constitutive (elastic) and geometrical models, this study involves a fully three-dimensional viscoelastic model of a plain weave composite with accurate characterization of the woven geometry. Comparisons between numerical predictions and experimental data clearly indicate that the creep compliance of the composite depends not only on the relaxation of the matrix, but also on the time-dependent flexural deformations of the woven fabric bundles. Predictions of the inhomogeneous deformation fields over the repeating cell agree with experimental observations.