On electrochemical cell modeling as basis for predicting corrosion failures in plastic encapsulated microelectronics

Despite extensive research over the past decades, corrosion of aluminum bond pads is still a major reliability risk for plastic encapsulated microelectronics. Nowadays even an increase in susceptibility for corrosion is observed for new waferfab technologies and encapsulation materials during reliability tests. The recent trend for the new generation encapsulation materials is to decrease the glass transition temperature. As a result reliability tests could be performed at temperatures well above this temperature, such that traditionally used translations between test and operational lifetime, i.e. the acceleration factor, are no longer valid. Consequently, a new acceleration model for bond pad corrosion is required, which is capable of predicting the lifetime of products from test performed at temperatures above glass transition temperature. In this work we will show the merits of electrochemical cell modeling on the understanding of corrosion failures in microelectronics. The model is based on the Poisson-Nernst-Planck equation for the transport of ions coupled to a generalized Frumkin corrected Butler-Volmer equation for the kinetics of the electrochemical reactions. We present results as an example to clarify our approach.