Effects of Filler Configuration and Moisture on Dissipation Factor and Critical Electric Field of Epoxy Composites for HV-ICs Encapsulation

TL;DR

This study models moisture uptake in epoxy composites used for IC encapsulation, analyzing how filler configuration affects electrical properties and proposing strategies to improve dielectric performance and reliability.

Contribution

It introduces a GEMS-Langmuir model for moisture transport, investigates moisture's impact on electrical conductivity and dielectric strength, and optimizes filler configuration for better performance.

Findings

Moisture ingress increases dissipation factor and reduces dielectric strength.

Filler configuration significantly influences moisture uptake and electrical properties.

Optimized filler arrangements can enhance dielectric performance and reliability.

Abstract

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.