Enhancing Heat Resistance and Dielectric Properties of Cyanate Ester Resins via Incorporation of a Fluoride‐Containing Tetrafunctional Cyanate Ester Structure

ABSTRACT Cyanate ester resins are widely applied in electronic information industries and aerospace fields due to their excellent dielectric properties, heat resistance, mechanical performance, and flame retardancy. With the rapid advancement of microelectronic technology, there is an urgent need to further enhance the comprehensive properties of cyanate ester resins. In this work, a novel fluoride‐containing tetrafunctional cyanate ester (FTFCy) monomer was synthesized and copolymerized with bisphenol A dicyanate ester (BADCy). The molecular structure and performance of the resulting copolymer resins were systematically investigated. The results demonstrate that the incorporation of FTFCy significantly improves the heat resistance, dimensional stability and dielectric properties of cyanate ester resins. Specifically, the 5% weight loss temperature of the BADCy/FTFCy resin containing 10 wt% FTFCy reaches 435.4°C, which is obviously higher than that of pure BADCy resin (419.5°C). The glass transition temperature ( T g ) of the BADCy/FTFCy resin with 30 wt% FTFCy increases from 288.5°C for the pure BADCy resin to 315.3°C. For the BADCy/FTFCy resin with 30 wt% FTFCy, the dielectric permittivity ( ε ) and dielectric loss tangent (tanδ) at a frequency of 1 MHz reach 2.78 and 0.0047, respectively, which are significantly lower than those of pure BADCy resin (3.07 and 0.0116). At 10 GHz, the ε and tanδ of this BADCy/FTFCy resin reach 2.70 and 0.0109, corresponding to reductions of 7.5% and 27.8% compared to pure BADCy resin (2.92 and 0.0151). Additionally, when the mass fraction of FTFCy is 30 wt%, the coefficient of thermal expansion (CTE)of the BADCy/FTFCy resin decreases to 58.3 ppm/°C, which is markedly lower than that of pure BADCy resin (65.6 ppm/°C). The BADCy/FTFCy copolymer resins exhibit outstanding comprehensive performances, making them promising candidates for advancing the development of printed circuit boards, electronic packaging materials, and radomes.