Flexible and insulating silicone rubber composites with sandwich structure for thermal management and electromagnetic interference shielding

Abstract

High integration development of electronics requires materials possessing excellent thermal conductivity, electromagnetic interference (EMI) shielding, and electrical insulation. In this work, Fe2O3 particles are deposited on carbon fibers (CF) and then utilized as fillers (CF@Fe2O3) in boron nitride/silicone rubber (BN/SR) to fabricate sandwich structured CF@Fe2O3/(BN/SR) composites, herein, BN/SR as top & substrate layer, and CF@Fe2O3 as middle layer. Orientation of BN in CF@Fe2O3/(BN/SR) composites realizes excellent in-plane thermal conductivity coefficient (λ∥), and the core-sheath structure of CF@Fe2O3 achieves good EMI shielding performance by the “absorption-reflection (transmittance)-reabsorption” process of electromagnetic waves, insulation modification of CF and the sandwich structure strengthen the electrical insulation. When the amount of BN and CF@Fe2O3 are 20.6 wt% and 45.5 wt%, respectively, the λ∥, EMI shielding effectiveness, volume resistance and breakdown strength of CF@Fe2O3/(BN/SR) composites reach 3.86 W/(m·K), 37.7 dB, 6.2 × 1014 Ω cm and 26.8 kV/mm, respectively, which are all higher than those of commonly fabricated CF/(BN/SR) composites with same amount of BN and CF (3.83 W/(m·K), 19.4 dB, 8.6 × 1013 Ω cm and 21.4 kV/mm). CF@Fe2O3/(BN/SR) composites possess better cooling effect (5.6 °C) than that of commercial silicon grease (QM850) on the testing platform of computer's central processing unit, whose functions are more abundant and have wide application prospects in electronics.