Flexible printed circuit board based on graphene/polyimide composites with excellent thermal conductivity and sandwich structure

In future, thermal management will play a crucial role in their design and fabrication, because the rapid development in miniaturization and versatility of electronic devices leads to the huge increase in power density. It is an inevitable trend to develop flexible substrate materials with high thermal conductivity, high heat flux, excellent stability and reliability. In this work, a new flexible print circuit board (G-FPC) containing a graphene film with sandwich structure was fabricated for heat dissipation. Firstly, multi-layer graphene film (M-GF) with 739.56 W m−1 K−1 in-plane thermal conductivity was prepared by high-temperature heat treatment (2900 °C) of GO film followed compression rolling process. Then, as-prepared M-GF and polyimide (PI) film were laminated and hot-pressed to fabricate G-FPC with epoxy resin as adhesive. As-fabricated G-FPC exhibits excellent flexibility, stability, and reliability, whose in-plane thermal conductivity can remain 98%, 81% and 88% after 10000, 15,000 and 20,000 bending times. Moreover, as-fabricated G-FPC has good heat dissipation capacity, which can significantly reduce chip temperature, 10 °C lower than traditional FPC with the power density of 0.42 W/cm2. The G-FPC with sandwich structure of PI/M-GF/PI will have potential applications in the flexible and wearable electronics in future, due to their versatility in heat dissipation, flexibility, stability and electronic interconnection as substrates. © 2020 Elsevier Ltd