Improving through-plane thermal conductivity of PDMS-based composites using highly oriented carbon fibers bridged by Al2O3 particles

Efficient thermal interface materials (TIMs) are urgently needed for heat dissipation of high-power density electronics. In this study, vinyl polydimethylsiloxane (PDMS) composites with the spatial alignment of carbon fibers (CFs) bridged by Al2O3 particles were fabricated by the flow field. The through-plane thermal conductivity (TPTC) of the composites with 24 vol% CFs and 47 vol% Al2O3 loading reached 38.0 W m(-1) K-1. The oriented CFs bridged by Al2O3 acted as the efficient through-plane thermal conductive network. Furthermore, the effects of shape factor (b/a), spatial angle (gamma) of CFs, and CF loading (V-f) on the TPTC were quantitatively discussed by steady-state finite element simulation combined with micro-computed tomography and machine learning. The positive contribution of the increased V-f to TPTC was in competition with the negative contribution of b/a and gamma, both of which increased with the increase of V-f. Moreover, b/a exerted more negative effects than gamma. The PDMS composites demonstrated excellent thermal stability (T-d = 407.5 degrees C, CTE = -55.3 x 10(-6) K-1), low compress modulus (1.71 MPa), and hardness (47 (Shore C)), which made them potential candidates for TIMs. This work offers a feasible method to prepare TIMs on large scale and refreshes the thermal conduction mechanism of TIMs by introducing the influencing factors (b/a and gamma).

Automated summary

Vinyl polydimethylsiloxane (PDMS) composites with spatially aligned carbon fibers (CFs) bridged by Al2O3 particles were fabricated and showed enhanced thermal conductivity. The effects of shape factor, spatial angle, and CF loading on thermal conductivity were quantitatively discussed. It was found that increased CF loading contributed positively to thermal conductivity, while shape factor and spatial angle had a negative effect.