Cyanate Copolymerized Epoxy Molding Compound: A Study on the Improved Thermal Performances by Optimizing Fillers Parameters

To meet the demand for high-temperature application requirements of encapsulation materials for third-generation wide-band semiconductors, a synergistic strategy was adopted in this study to improve the thermal resistance and thermal conductivity of epoxy resins through molecular structure design, filler compounding and interfacial modulation. Through the copolymerisation reaction of o-cresol novolac epoxy resin (EOCN) and cyanate ester (CE) to construct a rigid crosslinked network based on a triazine structure, the thermal decomposition temperature ( T 5% ) and glass transition temperature ( T g ) of the epoxy copolymer are enhanced to 431°C and 265°C, respectively, when the CE content reaches 60 mol%, which represents increases of 55.6% and 33.2%, respectively, compared to the common epoxy/methyl hexahydrophthalic anhydride (EOCN/MHHPA) system. In addition, the doping of SiO 2 fillers in the epoxy copolymer can effectively improve its thermal conductivity. The optimal SiO 2 particle size compounding ratio and surface coupling agent type were confirmed through orthogonal experimental results, which enabled the composites to achieve a significantly improved thermal conductivity of 0.632 W/(m K) while maintaining excellent thermal resistance ( T g of 266°C) and insulation (breakdown strength of 46.4 kV/mm), showing great potential to be used as epoxy mold compound (EMC) in the fields of high-temperature electronic packaging.