Edge-functionalized graphene as reinforcement of epoxy-based conductive composite for electrical interconnects

4-Aminobenzoyl-functionalized graphite is produced by the edge-functionalization of pristine graphite with 4-aminobenzoic acid via Friedel–Crafts acylation reaction. The edges of solid functionalized graphite are exfoliated with a high degree. The functionlization predominantly occurs at the edge region of graphite and the structure of pristine graphene in the interior basal planes is retained. The solid functionalized graphite is a promising precursor for the exfoliation into few layer graphene sheets in low boiling point solvents under ultrasonication. The functionalized graphene sheets are employed as nanoscale reinforcement to prepare epoxy-based conductive composite for electrical interconnects. The results show that the electrical conductivity of the composites with addition of 0.6 wt% functionalized graphene has an increase of 31.3% and the shear strength of the composites simultaneously improves from 8.7 MPa to 15.2 MPa. The covalent interactions between graphene and epoxy matrix provided by terminal amino groups can maintain the excellent dispersion of graphene in the matrix, leading to a 3D network. The graphene sheets come in contact with microscale silver fillers, constructing effective electrical bridges between the fillers. The increased flexibility of epoxy network leads to the reinforcement of shear strength. This technique extends the application of graphene in the conductive composites for electrical interconnects.