Rice Husk Ash: Effective Reinforcement for Epoxy-Based Composites for Electronic Applications

An agricultural waste-derived rice husk ash (RHA) as a source of silica was synthesized using a conventional low-cost method and subsequently used as a reinforcing agent to develop epoxy/RHA composites for microelectronic applications. The chemical composition and phase analysis of as-synthesized RHA was performed using x-ray fluorescence (XRF) spectroscopy and x-ray diffraction (XRD) techniques, respectively. The thermal, thermomechanical and dielectric properties of the epoxy/RHA composites were determined. The dispersion of RHA and the interfacial bonding between RHA and epoxy was studied using scanning electron microscopy (SEM). The addition of RHA in epoxy enhanced the glass transition temperature (Tg) of the composites significantly and all the composites showed better thermal stability than neat epoxy. The coefficient of thermal expansion (CTE) of the epoxy resin was reduced by 29.2% after the addition of 18.81 vol.% RHA. The storage modulus of epoxy/RHA composites was significantly enhanced up to 55.3% compared to neat epoxy. As compare to neat epoxy the composite with 18.81 vol.% RHA loading showed 44.7% improvement in microhardness. The dielectric constant of the epoxy decreased when the RHA was incorporated into it however epoxy/RHA composites exhibited insignificant change in dissipation factor compared to neat epoxy.