Effect of structural modification on the thermophysical properties of graphite films/diamond sandwich copper thermally conductive composite film

With the trend of integrating structure and function of electron device, there is an urgent need to develop new thermal management materials that have good mechanical and excellent thermal properties. In this study, a sandwich-like composite film with good thermal conductivity was fabricated by utilizing vacuum hot pressing technology, to combine graphite films (upper and lower layers) and copper with embedded diamonds (middle layer). Diamonds were embedded in copper films that were then brought into contact with graphite films, which established interconnected structure between the graphite and copper films. To enhance the interfacial bonding of graphite and copper, a complete and dense WC coating was deposited on the surfaces of the graphite films and diamonds. This study delved into the effects of this interconnection structure on the thermophysical properties of the composite films. Diamonds served as connecting bridges between the upper and lower graphite films, and they were examined by micromorphological characterization. When the sintering pressure was 20 MPa, the composite film with 30 vol% diamond attained a flexural strength of 125 MPa. Notably, the in-plane thermal conductivity of the composite film reached a peak value of 780 W/(m·K), and the out-of-plane thermal conductivity achieved a maximum of 211 W/(m·K). This translated to approximately 20 % and 200 % increments in the in-plane and out-of-plane thermal conductivities, respectively, in comparison to samples lacking interconnected structures. The enhancement of the heat dissipating efficiency within the composite films was simulated and analyzed using the acoustic mismatch model (AMM). In summary, an efficient approach was developed to implement interconnected structures in composite films. The methodology developed in this study holds potential for enhancing thermal conductivity in various applications. [Display omitted] •The interfacial bonding between graphite film and diamond was improved by surface modification.•By adding diamond in the middle layer of the "sandwich" type composite film to connect the upper and lower graphite films in the film, a graphite film-diamond interconnect structure is constructed.•The interconnectivity structure improves heat transfer efficiency by lowering interfacial thermal resistance, and boosts the three-dimensional thermal conductivity of the composite film while ensuring its high mechanical properties.