Change in dielectric relaxation with the presence of water in highly filled composites

Abstract

It is important to determine the dielectric characteristics of semiconductor encapsulation materials based on epoxy resins. We employed the dielectric spectroscopy technique to investigate the dielectric relaxation in the presence of water and how it changes the relaxation. It was observed that the dielectric relaxation of the material was significantly influenced by absorbed water, the local segmental motion (also known as Johari-Goldstein ( ) relaxation) was influenced most by the presence of the water, it was modified by the wet sample compared to dry one, and required high activation energy. The relaxation related to the glass transition was contributed by the cooperative motion (the -relaxation) of the epoxy resin system. The -relaxation was shifted to a low temperature in the wet sample compared to dry one. The relaxation was modeled with a clear Vogel-Fulcher-Tammann-Hesse (VFTH) behavior; the Vogel temperature of the wet sample was 8 K lower than the dry sample. The presence of water acts as a plasticizer for the molecular relaxation, and speed-up the cooperative process. The measured data were also used to estimate the electrical properties of the resin system by employing an effective-medium model together with a porous media continuum model by taking into account the physical properties of the system. It is already known that the influence of water in semiconductor packaging is important in sensitive applications. The presented measurements and the analysis method would be appreciated within the semiconductor packaging community to improve material selection and performance evaluation efforts.

Electrical characterization of epoxy-based molding compounds for next generation HV ICs in presence of moisture

“…In particular, it increases non linearly with the water content, passing from 0.19 eV to 0.47 eV as the relative water mass increases from 0.1 % to 0.2 %. This behavior is in contrast with what observed in literature for similar materials carried out at temperatures higher than the glass-transition one [18,21]. In the present work the analysis is carried out at temperatures significantly lower than the glass transition, which might cause a relevant difference in the involved physical effects and in their thermal dependencies.…”

“…In EMCs, the dielectric spectra generally show the effect of epoxy/filler interfacial polarization (ε' at low f), the material conductivity (ε'' at low f), and the dipolar relaxation times (ε'' peaks) [2,17]. Moisture influences the dielectric properties of EMCs in different ways [9,18]. Water molecules in dispersed states can cause a dipolar response, while water clusters or droplets may cause interfacial polarization.…”

The acquirement of desirable dielectric properties of carbon nanofiber composites based on the controlled crystallization

“…The percolation theory is described into the following equations by the power law 27,28 : dielectric constant of composites. [29][30][31] But in this paper, the interfacial effect between CNFs and HDPE was weak, and the dielectric constant resulting from interfacial polarization effect was not dominated.…”