Interfacial modified hexagonal boron nitride/cyanate ester composites with high thermal conductivity and low dielectric

Abstract This study investigates the use of cyanate ester (CE) as the matrix material and hexagonal boron nitride (hBN) as the functional filler. The hBN was surface-modified, blended with CE, and cured to form the composite material. A thermal conductivity model for the hBN/CE composites was developed, and the effects of hBN content, particle size, and surface functionalization on the formation mechanism of the thermal conductivity network were systematically investigated in conjunction with experimental results. The results indicate that when the hBN particle size ranges from 1 to 3 μm and its content is 16.70%, the thermal conductivity of the hBN/CE composite reaches 0.630 W/m·K, representing a 136% increase compared to the intrinsic thermal conductivity of the CE matrix (0.267 W/m·K). After modifying the hBN with 3 wt% silane coupling agent Z6020, the thermal conductivity of the 3.0% Z6020-hBN/CE composite further increases to 0.992 W/m·K, 3.71 times higher than that of the CE matrix. The experimental values are consistent with the simulation results. Moreover, the 3.0% Z6020-hBN/CE composite also shows a dielectric constant of 3.05 and a loss tangent of 9.30‰, with an improved bending strength of 102.7 MPa.