Pea-Pod-like Carbon Microspheres Encapsulated by Graphene-like Carbon Nitride for Enhanced Thermal Conductivity in Polyimide Films

Abstract

Owing to superior comprehensive performance, polyimide film (PI) has been extensively used as flexible substrate to support and fix electronic components. However, the current PI film has inferior thermal conductivity, especially in the vertical direction, causing failure of electronic devices in overheating conditions. Herein, an electrically insulating pea-pod-like filler with high thermal conductivity in both horizontal and vertical directions was prepared by encapsulating interconnected carbon microsphere (CM) with graphene-like carbon nitride (g-C3N4). The resultant thermal conductivity of PI film in horizontal and vertical directions has been improved by 11 (1.98 W m–1 K–1) and 2.4 (0.43 W m–1 K–1) times at 30 wt % CM@g-C3N4 loading, respectively. Furthermore, benefiting from satisfactory light absorption of CM@g-C3N4, the PI/CM@g-C3N4 film displays rapid heating capability under illumination. Meanwhile, the PI/CM@g-C3N4 film keeps intrinsic electrical insulation, thermal and dimensional stabilities. This work provides an effective method to solve the bottleneck of the current PI film in inadequate thermal conductivity.

High Out-of-Plane Thermally Conductive Polyimide Film for Electronic Thermal Management by the Incorporation of Core–Shell Ag/Polyimide Microparticles

“…To deeply understand the thermal conductivity improvement efficiency, the enhancement in thermal conductivity per unit filler loading as a function of filler loading is presented in Figure h. Certainly, compared to other thermally conductive fillers such as BNNS and graphene, ,,,− Ag-based fillers exhibit significant advantages in improving the thermal conductivity of polymers in the out-of-plane direction. Interestingly, PI/PIM@Ag-30 in our work exhibits the highest thermal conductivity improvement efficiency and the lowest filler content compared with most AgNP-based composites.…”

Structural Design and Research Progress of Thermally Conductive Polyimide Film – A Review

“…Large number of nuclei are deposited on the surface of the filler to form a coating when the solute content exceeds its saturation. [165] Liu et al [163] successfully prepared a pea-like filler using electrostatic self-assembly of carbon nitride (g-C 3 N 4 ) with carbon microspheres (CM). The 𝜆 ∥ and 𝜆 ⊥ of PI film containing 30 wt.% CM@g-C 3 N 4 could reach to 1.98 and 0.43 W (m K) −1 , respectively, they were improved by 11 and 2.4 times compared to pure PI film (Figure 15a).…”

“…When the loading of rGO was 8 wt.%, the 𝜆 of PI films prepared by conventional method was only 0.49 W (m K) −1 . [163] Copyright 2022, American Chemical Society. b) Schematic illustration of Al 2 O 3 @BN preparation and fabrication process of the Al 2 O 3 @BN&BN/PI film.…”

“…Coating molecules and the thermally conductive filler have opposite charges and rely on electrostatic self‐assembly to form the coating. [ 163 ] The Second one is chemical bonding mechanism. Strong chemical bonds are formed between the coating and thermally conductive fillers with active functional groups on the surface.…”

“…Figure 15. a) Schematic diagram of CM@g-C 3 N 4 formation. Reproduced with permission [163]. Copyright 2022, American Chemical Society.…”