Millefeuille‐Inspired Thermal Interface Materials based on Double Self‐Assembly Technique for Efficient Microelectronic Cooling and Electromagnetic Interference Shielding

Owing to the increasing power density of miniaturized and high‐frequency electronic devices, flexible thermal interface materials (TIMs) with the electromagnetic interference (EMI) shielding property are in urgent demand to maintain the system performance and reliability. Recently, carbon‐based TIMs receive considerable attention due to the ultrahigh intrinsic thermal conductivity (TC). However, the large‐scale production of such TIMs is restricted by some technical difficulties, such as production‐induced defects of graphite sheets, poor microstructure architecture within the matrix, and nonnegligible interfacial thermal resistance result from the strong phono scattering. In this work, inspired by the structure and production process of millefeuille cakes, a unique double self‐assembly strategy for fabricating ultrahigh thermal conductive TIMs with superior EMI shielding performance is demonstrated. The percolating and oriented multilayered microstructure enables the TIM to exhibit an ultrahigh in‐plane TC of 233.67 W m−1 K−1 together with an outstanding EMI shielding effectiveness of 79.0 dB (at 12.4 GHz). In the TIM evaluation system, a nearly 45 °C decrease is obtained by this TIM when compared to the commercial material. The obtained TIM achieves the desired balance between thermal conduction and EMI shielding performance, indicating broad prospects in the fields of military applications and next‐generation thermal management systems. Herein, a multifunctional thermal interface material is fabricated through the double self‐assembly technique to fulfil advanced thermal management applications concerning electromagnetic interference (EMI). According to the building of oriented multilayered microstructure and interfacial enhancement via nano‐coating, the composite maintains optimized coordination of the EMI shielding (shielding efficiency over 99.9999%) and thermal conductivity (in‐plane TC of 233.67 W m−1 K−1).