Micromechanics Models of Industrial Printed Circuit Boards for Bending Analysis

Industrial printed circuit boards (PCB)s are composites with complex geometrical features. In this study, a homogenization scheme was proposed to model bending, i.e., the primary deformation mode of industrial PCBs. Four-point bend tests were conducted on two types of industrial PCBs to measure their bending stiffness in the longitudinal and the lateral directions, respectively. The experimental results showed significant anisotropy and non-uniformity in the mechanical properties of the PCBs. PCB modelling was performed using the finite element method and a zoning approach. Three micrornechanics models, namely Cox-Krenchel model, modified Cox Lamina model and Pan model, were adopted. These models were compared to the classical rule of mixtures (ROM). Results showed that ROM and the micromechanics models gave the upper and the lower bounds, respectively, of the stiffness and overall response of the PCB in bending. Among the micromechanics model, Pan model gave the best prediction of elastic stiffness, at accuracy of more than 80%.