Fabrication of aligned carbon-fiber/polymer TIMs using electrostatic flocking method

Abstract

Directional assembly of anisotropic appearance filler in the composite is an effective way to obtain higher thermal conductivity thermal interface materials (TIMs). In this study, vertically aligned carbon fiber (VACF) scaffold reinforced polymer TIMs were fabricated using electrostatic flocking method, in which the aligned carbon fibers formed efficient heat conduction paths through the polymer matrix. By using high thermal conductivity mesophase pitch-based carbon fibers (mPCF) as filler, the maximum through plane thermal conductivity of the TIM with 13.4 wt% mPCF could reach up to 15.3 W/(m K), 60.2 times higher than that of the matrix, and the TIM also performed excellent flexibility. The influence of electrostatic flocking parameters on flocking effect was investigated. It is found that the electric field strength and the conductivity of fibers were the major factors to affect the vertical ratio of the mPCFs, and proper panels distance and fiber length were needed to acquire better flocking effect. In addition, the charging regular and the motion mechanism of fibers in electrostatic field were also discussed.