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Polymer-based thermally conductive materials are preferred for heat dissipation owing to their low density, flexibility, low cost, and easy processing. Researchers have been trying to develop a polymer-based composite film with excellent thermal conductivity (TC), mechanical strength, thermal stability, and electrical properties. However, synergistically achieving these properties in a single material is still a challenge. To address the above requirements, we prepared poly(diallyldimethylammonium chloride)-functionalized nanodiamond (ND@PDDA)/aramid nanofiber (ANF) composite films using a self-assembly strategy. Owing to a strong interfacial interaction arising from electrostatic attraction, ND particles attract strongly along the ANF axis to form ANF/ND “core–sheath” arrangements. These assemblies self-construct three-dimensional thermally conductive networks through ANF gelation precipitation, which was analyzed as the key parameter for the realization of high thermal performances. The as-prepared ND@PDDA/ANF composite films exhibited high in-plane and through-plane TCs up to 30.99 and 6.34 W/m·K, respectively, at a 50 wt % functionalized ND loading, representing the optimal values among all previously reported polymer-based electrical insulating composite films. Furthermore, the nanocomposites also achieved other properties necessary for realistic applications, such as outstanding mechanical properties, excellent thermal stability, ultra-low thermal expansion coefficient, excellent electrical insulation, low dielectric constant, low dielectric loss, and outstanding flame retardancy. Thus, this excellent comprehensive performance enables the ND@PDDA/ANF composite films to be used as advanced multifunctional nanocomposites in thermal management, flexible electronics, and intelligent wearable equipment.

Three-dimensional integrated packaging with through-silicon vias (TSV) can meet the requirements of high-speed computation, high-density storage, low power consumption, and compactness. However, higher power density increases heat dissipation problems, such as severe internal heat storage and prominent local hot spots. Among bulk materials, diamond has the highest thermal conductivity (≥2000 W/mK), thereby prompting its application in high-power semiconductor devices for heat dissipation. In this paper, we report an innovative bottom-up Cu electroplating technique with a high-aspect-ratio (10:1) through-diamond vias (TDV). The TDV structure was fabricated by laser processing. The electrolyte wettability of the diamond and metallization surface was improved by Ar/O plasma treatment. Finally, a Cu-filled high-aspect-ratio TDV was realized based on the bottom-up Cu electroplating process at a current density of 0.3 ASD. The average single-via resistance was ≤50 mΩ, which demonstrates the promising application of the fabricated TDV in the thermal management of advanced packaging systems.

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