Evaluation and Modeling of Electrochemical Migration on Printed Circuit Boards

Title of Document: EVALUATION AND MODELING OF ELECTROCHEMICAL MIGRATION ON PRINTED CIRCUIT BOARDS Xiaofei He, PhD, 2014 Directed by: George Dieter Chair Professor Michael G. Pecht, Assistant Research Scientist Michael H. Azarian, Department of Mechanical Engineering Electrochemical migration (ECM) is the growth of conductive metal filaments on a printed circuit board (PCB) through an electrolyte solution under a DC voltage bias. ECM can cause a reduction in surface insulation resistance (SIR) between adjacent conductors and lead to intermittent or catastrophic circuit failures. The kinetics of the electrochemical migration process between copper traces in deionized water was investigated using electrochemical impedance spectroscopy and cyclic voltammetry. The rate limiting step was identified to be anodic diffusion before and during dendritic growth. Based on this, a model was developed to describe the kinetics of electrochemical migration under condensed and non-condensed conditions between copper conductors on printed circuit boards using Nernst Planck equation and impedance measurement. It was found that by acquiring electro-active ion surface concentration at anode with the help of impedance measurement and by considering migration and diffusion in the bulk ion transport, the model matches the experimental results quantitatively. Historical models are applied to the experimental results and compared with the model of this study.