Electrochemical migration behavior of Ag-plated Cu-filled electrically conductive adhesives

Abstract

The electrochemical migration (ECM) behavior of the electrically conductive adhesives (ECAs) filled with pure Ag powder or Ag-plated Cu composite powder with varied Ag:Cu ratios was investigated under the condition of applying constant voltage and distilled water environment. ECM resistance was determined from the current-time curves. The microstructure and composition of ECM dendrite products were analyzed by SEM/EDS and XRD. It was found that the ECM resistance of Ag-plated Cu composite powder-filled ECAs was evidently higher than that of pure Ag powder-filled ECAs. The Ag:Cu ratio of composite powder in ECAs had notable influence on ECM resistance, which was enhanced with the decrease of Ag:Cu ratios. The composition of dendrites formed between cathode and anode during ECM process was not uniform for Ag-plated Cu-filled ECAs. An ECM inhibiting mechanism of Ag-plated Cu composite powder was proposed according to analysis of the electrochemical impedance spectroscopy, Tafel plot and dendrite composition.