Electric-field-coupled rotary DBD plasma-modified mBN enables epoxy encapsulation with both high thermal conductivity and excellent electrical insulation: high material utilization index

The rapid development of artificial intelligence data centers has driven the demand for epoxy (EP)-based encapsulation composites with high thermal conductivity and electrical insulation for high-power-density power electronics. However, poor interfacial compatibility between boron nitride microplatelets (mBN) and EP generates microvoids and local electric-field distortion. Here, an electric-field-coupled rotary dielectric barrier discharge reactor is developed for uniform plasma hydroxylation of mBN using water as a green reaction medium. The coupling of surface and volume discharges with dynamic rotation suppresses powder agglomeration and enables homogeneous surface functionalization. The resulting mBN-OH/EP composite exhibits a thermal conductivity of 0.472 W/(m·K), representing a 105.2% enhancement over pure EP, and a breakdown strength of 120.02 kV/mm, 14.48% higher than that of untreated mBN/EP. Improved interfacial compatibility also alleviates local electric-field distortion and reduces the apparent partial-discharge charge by approximately 43%, achieving a favorable balance between thermal conductivity and electrical insulation. Furthermore, a Material Utilization Index (MUI) is introduced to quantify material and energy efficiency. The proposed method exhibits higher utilization efficiency than conventional physical, chemical, and static plasma modification approaches, providing a green and potentially scalable strategy for preparing high-performance thermally conductive and electrically insulating composites.