Passivation of the Exposed Silver Electrodes on a Tuning Fork Crystal Oscillator by Chronoamperometry

Abstract

We present a simple passivation method for the silver electrodes on a tuning fork crystal oscillator to be used in sensor applications. To cover their three dimensional shapes, a solution based process, chronoamperometry, was used. Both depth profiling and electrical characterization were performed to verify the validity of the selected process. We found that sulfur contamination mainly caused the resonance frequency degradation of the unprocessed oscillator. In contrast, the resonance frequency of the passivated oscillator remained unchanged in time up to 3258 h. This robustness is attributed to the formation of the AgCl and Ag2O passivation layer by chronoamperometry. (C) 2012 The Japan Society of Applied Physics