Failure evaluation of flexible-rigid PCBs by thermo-mechanical simulation

In this present work the finite element method has been used for the simulation models in order to develop tools for the early stages of product design. The objective is to develop simulation models for Flexible Printed Circuits Boards (PCBs) in a flex-rigid concept in the shape of a wrist device to evaluate its critical stress and strain when this device is submitted to thermal loading considering FR4 and Polyimide substrates as the constitutive materials of the board with BGA attached components. The critical points are the mismatch of the coefficient of thermal expansion of different materials as well as the thermoset viscoelastic nature of the polyimide. In the end of this present study it will be shown that additional research should be done to the final product. In this paper we will show the preliminary results of strain and stress distribution induced by thermo loading using a commercial finite element package.