Vertically aligned liquid metal thermal pad with excellent electromagnetic shielding and ultra-high compressibility

Abstract

With the increasing integration level of modern electronics, flexible highly thermally conductive and electromagnetic interference shielding (EMI) materials were urgently demanded in electronic devices. Traditionally carbon or solid metal fillers are widely used as a reinforcement to fabricate a flexible thermally conductive and EMI shielding materials. However Due to the trade-off between mechanical and thermal properties, it is difficult to further improve the performance of solid filler/polymer composites. Here in this work based on the intrinsic excellent electrical and thermal conductivity of liquid metal (LM), we embedded the LM network structure vertically in the silicone gel and fabricated a vertically aligned LM(VALM) composites. Compared to the randomly dispersed LM composites, VALM composite exhibits high through plane thermal conductivity (κ⊥: 6.08 W/m·K) and excellent EMI shielding efficiency (SE) (minimum and maximum EMI SE for VALM2 were 33.2 dB and 39.5 dB). In addition, due to the fluidic nature of LM, composite materials exhibit excellent softness and flexibility (compression modulus of 0.56 MPa). Practical heat dissipation test results and EMIS efficiencies demonstrate usefulness of VALM composite in next-generation electronics.