As the amount of transistors double every two years as described by Moore’s law and the energy density increases correspondingly, the huge amount of heat generated cannot be dissipated efficiently. Thermal interface materials (TIMs) is one of the cooling solutions applied between chip-chip interface and chip-substrate interface. Owing to the high in-plane thermal conductivity of graphene (Gr), this low-dimensional carbon-based nanomaterial has been studied for thermal dissipation. Matrix-free Gr carpets have also been demonstrated as high performance heat-spreaders in electronic packaging. However, the performance of graphene as a TIM was limited due to the poor out-of-plane thermal conductivity. Herein, this work is focused on developing 3D Graphene foam with dielectric propert...[ Read more ]

As the amount of transistors double every two years as described by Moore’s law and the energy density increases correspondingly, the huge amount of heat generated cannot be dissipated efficiently. Thermal interface materials (TIMs) is one of the cooling solutions applied between chip-chip interface and chip-substrate interface. Owing to the high in-plane thermal conductivity of graphene (Gr), this low-dimensional carbon-based nanomaterial has been studied for thermal dissipation. Matrix-free Gr carpets have also been demonstrated as high performance heat-spreaders in electronic packaging. However, the performance of graphene as a TIM was limited due to the poor out-of-plane thermal conductivity. Herein, this work is focused on developing 3D Graphene foam with dielectric properties and synthesizing and testing Graphene based composites as thermal interface materials.

In this work, three types of 3D Graphene structures, freestanding dielectric Graphene foam (GF@Al₂O₃), Graphene oxide coated Cu (Cu@GO) and Aluminum oxide decorated reduced Graphene oxide coated Cu (Cu@rGO@Al₂O₃) are reported. It is demonstrated according to the experimental results that there’s dramatically enhancement in thermal and dielectrical properties. Meanwhile, the interfacial modification on GF by phase change metal alloy (PCMA) is conducted which shows excellent reduction on thermal interface resistance.

This work is aimed to accomplish the practical application of Graphene as thermal interface materials commercial products, which shows competitive thermal and mechanical properties compared with traditional TIMs and to contribute my own effort solve the interfacial thermal dissipation problems in electrical packaging fields.

Keywords: thermal interface materials, Graphene, Graphene foam, reduced Graphene oxide, thermal conductivity, interface thermal resistance.

(Supervisors: Prof. Matthew Yuen, Prof. Baoling Huang)