Silver-Decorated Boron Nitride Nanosheets as an Effective Hybrid Filler in PMMA for High-Thermal-Conductivity Electronic Substrates.

High-thermal-conductivity and low-dielectric-loss polymer nanocomposites have gained tremendous attention in microelectronics technology. Against this background, the present study deals with the development of a high-thermal-conductivity, low-dielectric-constant, and low-loss polymer nanocomposite based on silver nanoparticle (AgNP)-decorated boron nitride nanosheets (BNNSs) as the filler in poly(methyl methacrylate) (PMMA) matrix. The nanocomposites were prepared through a facile solution-blending process. Elemental mapping of the prepared nanocomposite indicates the uniform distribution of filler particle in PMMA matrix. An impressive high-thermal conductivity (TC) enhancement of around 363% was achieved for nanocomposite of 0.35 of hybrid filler (1.48 W/m K) compared to pristine PMMA (0.32 W/m K). The addition of AgNP reduces the thermal contact resistance ( ) by bridging individual BNNS, thereby improving thermal transport. Measured TC values were fitted with a theoretical model that showed good agreement. Dielectric measurements performed at radiofrequencies and microwave frequencies revealed that the nanocomposites show a low dielectric constant (<5), low loss (10), and very low alternating current conductivity (10 S/cm). The results suggest that silver-decorated BNNS is a promising hybrid filler for effective thermal management.