VOLUME 18 NUMBER 2 (July to December 2025)

Thermal characterization of hexagonal boron nitride/polyester composites for microelectronic applications

In a world constantly seeking sustainable solutions, the quest for advanced materials with superior mechanical and thermal properties remains crucial. Composite materials have emerged as a promising avenue, blending the strength of traditional materials with innovative reinforcements, paving the way for applications ranging from aerospace to automotive industries. In this study, we embark on a comparative journey, delving into the world of composite materials by scrutinizing hexagonal boron nitride (hBN) reinforcements infused within a polyester matrix. This research explores the thermal attributes of these composites, illuminating their potential in various engineering applications. The composites’ thermal conductivity and glass transition temperature increase with hBN content, whereas the coefficient of thermal expansion decreases. Hexagonal boron nitride (hBN)-reinforced unsaturated polyester composites were prepared with untreated and silane-treated hBN fillers (10–40 wt%). Silane surface modification of hBN significantly improved filler dispersion and interfacial adhesion. The thermal conductivity of neat polyester (0.38 W/m·K) increased to 1.76 W/m·K with 40 wt% untreated hBN and to 2.16 W/m·K (a 568% enhancement) with 40 wt% silane-treated hBN. The percolation threshold decreased from ~32.5 wt% (untreated) to ~27.5 wt% (silane-treated). The glass transition temperature rose from 78°C (neat polyester) to 97.8°C (untreated hBN) and 103.5 °C (silane-treated hBN) at 40 wt% loading. The coefficient of thermal expansion decreased from 68 × 10⁻⁶/°C to 56.9 × 10⁻⁶/°C and 55 × 10⁻⁶/°C for untreated and silane-treated composites, respectively, at the same filler content. These improvements, achieved while maintaining good processability and a low dielectric constant, demonstrate the potential of silane-treated hBN/polyester composites for thermal management in microelectronic applications.