Enhanced thermal conductivity and lower density composites with brick-wall microstructure based on highly oriented graphite nanoplatelet: Towards manufacturable cooling substrates for high power density electronic devices

Sustainable and smart thermal management in modern wearable electronics is becoming increasingly important for developing the reliability and preventing premature failure of electronics. In this work, we report on the development of a new type of nanocomposite based on highly oriented graphite nanoplatelets (GNPs) that is functional as a thermal substrate with enhanced thermal conductivity and efficient cooling effect via a manufacturable process. Firstly, GNP/CMC (sodium carboxymethyl cellulose) nanocomposite films (GMFs) were fabricated in mass industry available level by gap coating method, in which GNPs were well preferred due to the driving interface wettability and interaction of CMC, resulting in high in-plane thermal conductivity. Then, GNP/CMC thermal plates (GTPs) with enhanced thermal conductivity (∼29.5 W (m K)^-1) and a low density (1.14 g cm^-3) were produced using as-prepared GMFs and epoxy as fillers and adhesive by lamination and hot pressing method, thus exhibiting an outstanding heat dissipation on electronic cooling. Under a chip power of 1-3 W, the temperature of chip attached on our GTP substrates can be 18.9 ∼ 47.7 °C lower than that on classic polycarbonates (PC) substrate. The obtained boosted thermal conductance of GTPs is primarily attributed to their biomimetic 'brick-wall' microstructure with GMFs and epoxy as brick and cement, which is the same as the structure of shell with mineral and protein as brick and cement, respectively. With enhanced thermal conductivity and manufacturability, our work provides a new promising technical approach in the next generation of thermal management of high power density electronics and wearable electronics.