Modulation on dielectric properties of epoxy laminates by hyperbranched cyanate ester

Abstract

In response to the demands of the current era characterized by high-speed communication, achieving superior signal integrity in high-frequency and high-speed circuits necessitates imposing stringent requirements on various properties of electronic devices, including a low dielectric constant, minimal loss at high frequencies, and superior mechanical properties. In this study, trimethylolpropane (TMP) was utilized as the core, and bisphenol A cyanate ester (CE) was employed as the grafting monomer. A hyperbranched cyanate ester (HBCE) was synthesized by integrating the –OCN groups of TMP and CE with –OH. Subsequently, a novel laminated board was fabricated by modifying epoxy resin (EP) with the synthesized hyperbranched cyanate ester. The hyperbranched structure of HBCE was comprehensively characterized using nuclear magnetic resonance and Fourier-transform infrared spectroscopy. Dielectric performance evaluations revealed that HBCE effectively reduces both the dielectric constant and the dielectric loss of the laminate. At 10⁶ Hz, the dielectric constant of the EP-HBCE-15wt% laminate is 3.108, with a dielectric loss of 0.00615. The reduction in dielectric constant is attributed to an increase in the free volume fraction within the system and a decrease in the content of polarized functional groups. The bending strength of EP-HBCE-15wt% laminate reaches 503 MPa, and the bending modulus reaches 14.5 GPa. The insulation and mechanical tests results indicate that the laminated board exhibits excellent performance characteristics, meeting the stringent standards required for electronic-grade copper-clad laminates.