Abstract
Electronic devices often fail during service in moist environments by coupled anodic corrosion and cathodic electrodeposition processes, which lead to dendrite formation and eventually cause a short circuit in the device. As a preliminary step in the investigation of the failure mechanism, CrCuCr metallizations on alumina substrates were tested in bulk solutions of varying compositions by means of a specially developed potential bias step test and by cyclic voltammetry (CV). Short-circuit potentials measured in the step tests were found to increase with increasing pH, implying a decreasing growth rate of the dendrites. The morphology of the predominantly copper dendrites was also observed to vary with pH and dendrite composition. For pH values of 8.3, uniform corrosion and deposition were observed at anodic and cathodic sites, respectively. A comparison of CV data for metallized substrates was found to be consistent with results obtained for the relevant pure metals. The CV data were also in agreement with the results of the bias step test, which indicates that the hydrogen evolution reaction is a controlling step in the initiation of the failure process for the conditions examined here. In addition, this study has defined two complementary and mutually consistent electrochemical techniques that provide an effective approach to the investigation of dendrite growth and determination of the relative susceptibility to failure.
