Effects of film viscosity and electric field strength on alignment of graphene flakes in B-stage graphene-epoxy composite film

Abstract

B-stage epoxy film is one of the most widely used adhesive in electronic packaging. Since its ad-vantages in processing, B-stage adhesive film is being used as advanced electronic packaging technologies such as anisotropic conductive films (ACFs) and die attach film for 3D packaging. Graphene, a layer of carbon atoms, has been paid attention to many different scientists and engineers due to its own unique and excellent properties. There are various potential applications studied such as elec-trode, gas sensor, and transistor, and one of the applications of graphene is graphene-polymer composite, which graphene flakes are incorporated into polymeric matrix. Recent studies on graphene-polymer compo-site have demonstrated that small amount of graphene flakes improved the properties of neat polymer mate-rials significantly. Therefore, graphene flakes can be an effective filler for B-stage film for electronic packag-ing. Moreover, recent studies on nano-sized filler-polymer composites focus on tailoring the structure of the composites. Especially alignment of nanoparticles or nano-flakes such as carbon nanotubes and gra-phene flakes, has widely studied. Alignment methods such as mechanical strain, in-situ polymerization, and electric or magnetic field application were studied on carbon nanotubes and graphene flakes in polymeric composite materials. However, most of the studies are focused on bulk-type composite, not film-type com-posite, which various applications are possible. In this study, alignment of graphene flakes in B-stage graphene-epoxy composite film, was studied. Commercial graphene flakes were used, and B-stage graphene-epoxy composite film was fabricated by pre-paring graphene-epoxy resin by solution mixing process. During preparation, sonication of graphene flakes in organic solvent was done, therefore the effects of sonication time on the dimension and quality of graphene flakes were demonstrated. After the film was prepared, characterization of B-s...