Nanocomposites for future electronics device Packaging: A fundamental study of interfacial connecting mechanisms and optimal conditions of silane coupling agents for Polydopamine-Graphene fillers in epoxy polymers

Abstract

With the ultra-fast development of high-performance semiconductor devices through the increase of power and on-chip integration density, it is essential to maximize heat transfer efficiency and explore new nanomaterials for applications in thermal interface materials (TIMs). Graphene-based epoxy nanocomposites are becoming one of the most promising candidates for the next generation of highly efficient, lightweight TIMs due to the unique properties of graphene – extraordinarily high thermal conductivities and large surface areas. However, they can have poor interfacial interactions with polymers owing to the lack of functional groups on the surface of graphene, leading to phonon scattering within the contact interfaces. In this work, graphene nanosheets are fabricated by a large-scale and low-cost liquid exfoliation method. Through fundamental understandings of interfacial connecting mechanisms and intelligent modifications of graphene with polydopamine (PDA) and silane coupling agents, optimized reaction conditions between silane coupling agents and PDA-graphene serve as the main contributor to the high thermal conductivity of the epoxy nanocomposites with low viscosity and effective filler dispersion. The graphene epoxy nanocomposites thus obtained have an out-of-plane thermal conductivity of 0.73 W/mK at 5 wt% loading, corresponding to a 400% improvement in thermal conductivity as compared to that of neat epoxy. In addition, the nanocomposites also have a lower coefficient of thermal expansion (CTE), higher thermal stability, lower moisture adsorption, and effective electrical insulation. From performance tests on the TIMs, they present better cooling capabilities and heat dissipation as corroborated through both experimentation and simulation, supporting the idea that our findings have potential to be applied in the next generation of TIMs for high-power and high-density integrated circuits (ICs) as well as in advanced packaging.