Thermally conductive and electromagnetic interference shielding polydimethylsiloxane composites with vertically oriented carbon fibers obtained by gravity-magnetic actuation

With the rapid advancement of the highly integrated microelectronics industry, the growing demand for composite materials that offer both high thermal conductivity and effective electromagnetic interference (EMI) shielding to ensure the long-term stability of electronic devices is becoming increasingly significant. However, achieving high through-plane thermal conductivity remains challenging due to the difficulty in establishing continuous thermal conduction pathways through the composite thickness. In this work, polydimethylsiloxane (PDMS) composites with vertically oriented Carbon fiber (CF) structures were successfully fabricated through cast molding and gravity-magnetic field co-induced CF alignment. At 23.5 vol% CF content, the composite exhibits a through-plane thermal conductivity of 12.26 W/(m⋅K), a thermal conductivity enhancement (TCE) of 7500 %, and an electromagnetic interference shielding efficiency (EMI SE) of 27.9 dB. In addition, the influences of CF content on the anisotropic thermal conductivity and EMI shielding properties of the composites were examined. This CF/PDMS composites with vertically aligned CF structures have a broad range of potential applications in thermal management and EMI shielding, such as thermal interface materials in high-power chips, LEDs, 5G RF modules.