Development of epoxy-aluminum nanocomposite dielectric material with low filler concentration for embedded capacitor applications

This paper presents the development of epoxy-aluminum nanocomposites as a dielectric material by adopting a relatively low concentration of filler to obtain high dielectric constant simultaneously retaining low dielectric loss. Epoxy-aluminum nanocomposite is modeled as a three phase material and dielectric constant of the composite is evaluated using this model. Experimental analysis is done and dielectric properties of the composite is characterized as a function of filler loading and frequency. It is observed that the theoretical and experimental analysis match well at lower filler concentrations. Dielectric property measurement demonstrated that, for composite containing 18 wt% 70 nm aluminum, a dielectric constant of 25 and a low dissipation factor of 0.06 can be achieved. The dielectric constant of epoxy-aluminum composite is increased by factor 7 at this lower filler loading as compared with that of pure epoxy matrix. The increase in dielectric constant with addition of aluminum is attributed to interfacial polarization. An attempt is made to understand the effect of inter particle distance on the dielectric properties of the nanocomposite. It is seen that the dielectric constant attained maximum value at 18 wt% filler loading, for which the inter particle distance reaches a value almost equal to the filler diameter (70 nm) itself.