Metal Migration (Ag, Cu, Pb) in Encapsulated Modules and Time-to-Fail Model as a Function of the Environment and Package Properties

Metal migration occurs between biased lands and, under conditions conducive to electrocrystallization, causes dendritic growths and failure. A model, based on the physics of condensation, ionic migration and thermally activated mechanism, was verified with polymer-encapsulated modules (Ag lands) under accelerated conditions of temperature, humidity and voltage. The acceleration factors agree with the predictions. Additional results with Ag, Cu, Pb films showed that oxides and process contaminants constitute strong migration factors controlling passivation against the electrochemical process.