Modeling electrochemical migration through plastic microelectronics encapsulations

Plastic encapsulations will absorb moisture in humid environments due to their hydrophilic nature, this in combination with the inherent ionic contamination of the plastic will result in an electrolyte. This electrolyte might pose several reliability issues for the package and the encapsulated microelectronic circuit, such as electrochemical migration and bond pad corrosion. The corresponding failure mechanisms are associated with ionic currents through the package and electrochemical processes at e.g. the leads or bond wires. In this paper we present a generic mathematical framework for modeling ionic currents and electrochemical processes. We will apply this framework to electrochemical migration of metal between the leads of a plastic encapsulation, and show results for the transient formation of migration fluxes through the plastic encapsulation.