Dendrite growth in electronic materials and devices: a perspective and the electrochemical mechanism

摘要

The presence of gold contamination on the alumina dielectric of a RF power transistor caused the development of dendrites during qualification testing at 85 °C and 85 % relative humidity with an applied bias. Possible mechanisms for dendrite formation are discussed. In all cases, the mechanism are similar and are due to the fact that the devices during processing were immersed in a gold plating bath for several seconds without an applied voltage. During this time, silver and copper dissolved from layers containing these metals displacing gold ions from the plating bath. The devices were tested at high temperature (85 °C) and high relative humidity (85 %), as a part of the qualification procedure. The dendrites formed during testing on the dielectric in areas contaminated with Au. To avoid such problems, it has been recommended that the voltage be applied before the device is immersed in the plating bath.