Thermal, Electrical and Mechanical Properties of Expanded Graphite and Micro-SiC Filled Hybrid Epoxy Composite for Electronic Packaging Applications

Abstract

The synthesis of high-thermal-conductivity expanded graphite (EG) by a physical method from natural graphite flakes using zinc nitrate hexahydrate is described herein. This article establishes thermal conductivity studies of the epoxy composite system containing a hybrid of EG, a soft material, and micro-SiC, a hard material, with different filler fractions. To verify the texture and appearance, the filler materials were characterized by polarized light and scanning electron microscopy. The thermal conductivity of the fabricated hybrid epoxy composites was analyzed by a guarded hot plate meter technique. The electrical properties of the hybrid composite were evaluated by a four-point potentiometer. The single-lap shear strength of optimized composition was observed under a universal testing machine. The thermomechanical behavior and thermal stability of the hybrid composites were investigated through dynamic mechanical analysis and thermogravimetric analysis, respectively. The dispersive status and synergistic effect of the hybrid filler inside the epoxy matrix were studied through fracture surface analysis by scanning electron microscopy. With the addition of 15 wt.% EG and 15 wt.% micro-SiC to the epoxy resin, thermal conductivity of up to 2.24 W/mK was achieved for the hybrid composite, which was an 11.6-fold improvement over unaided epoxy.