  Molding compounds (MCs) have been used extensively as an encapsulation
material for integrated circuits, however, MCs are susceptible to moisture and
charge spreading over time. The increase in dissipation factor due to the
increase of parasitic electrical conductivity ({\sigma}) and the decrease in
dielectric strength (E_MC^Crit) restrict their applications. Thus, a
fundamental understanding of moisture transport will suggest strategies to
suppress moisture diffusion and broaden their applications. In this paper, we
1) propose a generalized effective medium and solubility (GEMS) Langmuir model
to quantify water uptake as a function of filler configuration and relative
humidity; 2) investigate the dominant impact of reacted-water on {\sigma}
through numerical simulations, mass-uptake, and DC conductivity measurements;
3) investigate electric field distribution to explain how moisture ingress
reduces E_MC^Crit; and finally 4) optimize the filler configuration to lower
the dissipation factor, and enhance E_MC^Crit. The GEMS-Langmuir model can be
used for any application (e.g., photovoltaics, biosensors) where moisture
diffusion leads to reliability challenges.
