Pie-rolling-inspired construction of vertical carbon fiber high thermal conductivity hybrid networks

Carbon fiber (CF) with a high thermal conductivity (Tc) of 1100 W m−1 K−1 along its one-dimensional (1D) direction is considered a promising filler for fabricating high-performance thermal interface material (TIM). However, Tc in the radial direction of CF is far less than 10 W m−1 K−1 determines that Tc highly depends on the orientation of CF. In this study, polydimethylsiloxane (PDMS)/short carbon fibers (SCFs)/Al spherical particle (PDMS/SCFs/Al) composite is firstly prepared. SCFs are then arranged into horizontal (0°), inclined (45°), and vertical (90°) orientations, respectively, utilizing a convenient "pie-rolling" method that does not rely on any specific instrument. As a result, the vertically oriented SCFs together with Al spherical particles establish an effective thermal conductivity-three-dimensonal (3D) network, and the Tc of the through-plane is as high as 10.46 W m−1 K−1, while the in-plane Tc is 6.23 W m−1 K−1 measured from a steady-state method. The anisotropic thermal conductivity is also verified by a hot-disk method. The working mechanism and thermal conductivity of oriented SCFs and Al spherical particles composites are being studied using finite element simulation. In addition, the change in surface temperature of the composites during heating and cooling stage is observed using an infrared thermal imaging camera. A 16 ℃'s temperature decline demonstrates that the high-efficiency heat transfer along the vertical orientated carbon fiber-based 3D network was successfully realized in SCF-90 when it was used as a TIM between a bare die and heat pipe of a laptop. This work illustrates the prospect of using SCFs to prepare a high thermally conductive 3D network could be used in the future thermal management of electronic devices.