Non-Fickian moisture properties characterisation and diffusion modeling for electronic packages

The rate of moisture diffusion in the IC packaging materials was found to be dependent not only on the concentration gradient as described by Fick´s Law, but also on the moisture concentration itself. This non-Fickian behaviour poses a challenge for the characterisation of moisture diffusivity of packaging materials which is conventionally based on Fick´s diffusion law. This paper presents an integrated non-linear finite element diffusion modeling and optimisation procedure that is capable of characterising moisture diffusivity as a function of moisture concentration from a single moisture sorption experiment