Cyclic Fatigue Testing as a Reliability Assessment Method for HDI Circuit Boards

Abstract

This paper presents a high-frequency mechanical fatigue method to evaluate the reliability of high-density circuit boards. Cyclic bending tests were performed on custom test vehicles containing representative Printed Circuit Board (PCB) features, including stacked microvias and copper traces, using electrodynamic shakers and a purpose-built stage. Electrical resistance was monitored continuously to detect failures in real time. Finite Element Method (FEM) simulations were used to determine the stress and strain distributions in the boards during the thermal and mechanical loading. Post-test failure analysis by metallographic cross-sectioning characterized the samples failure behavior. A comparison between the observed failure modes and those produced under thermomechanical loading provides insight into the encountered degradation mechanisms. The testing system can replicate a variety of loading scenarios and provides lifetime data up to high-cycle fatigue regime to support reliability predictions in High-Density Interconnect (HDI) circuit boards.