Low-transmission-loss modified cyanate ester materials for high-frequency applications

Cyanate esters cure through cyclotrimerization of reactive cyanate functional groups into resins with three-dimensional and densely cross-linked structures. i.e. triazine resins, which have low dielectric constants and high glass transition temperatures. Aryl cyanate esters had been of great interest as materials for low dielectric-constant circuit boards; however, their dielectric properties could not satisfy the demands for high-speed communication. We have found that novel modified cyanate ester resins will show much lower dielectric constant/loss and better compatibility with high molecular weight thermoplastic polymers. Judging from the structure/property relationships obtained through the analytical results of their chemical structures and the studies on their visco-elastic properties, we have concluded that the above characteristics were due to the unique resin structures. We developed semi-intermolecular-penetrating network (semi-IPN) materials by combining modified cyanate ester resins with thermoplastic polymers which provide low dissipation factor in GHz frequency range. Circuit boards with glass cloths and these materials demonstrated low transmission losses in the frequency range up to 30 GHz. These excellent microwave properties will ensure an advantage to the novel modified cyanate ester resins as materials for circuit boards in high-speed communications technology.