Fluorine-free bismaleimide triazine resin of ultra-low dielectric loss for high-frequency communication

The advancement of high-frequency integrated circuits urgently demands dielectric materials with both low dielectric constant ( D k ) and dielectric loss (tan δ), as well as environmental compliance through fluorine-free formulation. Bismaleimide (BMI) resins, qualified as low-dielectric polymer candidates, are limited by pronounced dipolar polarization by the highly polar imide groups (–N–C=O) and the narrow processing windows. The rational design of BMI monomer and composite formulations appears to be of urgency. Herein, we propose a low dielectric bismaleimide triazine (BT) resin based on a novel fluorine-free BMI monomer constituted of a bulky 4,4′-cyclohexylidenebisphenoxyl moiety with N -phenylmaleimide termini, named P(ZMI). The system displays an elucidated curing mechanism and quantifiable kinetic parameters, with a favorable curing profile at low temperature and a broad processing window. Remarkably, P(ZMI) achieved excellent dielectric performance with a D k of 2.84 and a breakthrough ultra-low tan δ of down to 0.0007 at 10 GHz. The ultra-low dielectric loss is achieved by suppressing polarization relaxation and defect-induced dissipation through uniform charge distribution and optimized multiphase compatibility, leading to the dual minimization of intrinsic and extrinsic loss components. This work establishes a synergistic design paradigm that concurrently delivers superior dielectric properties, environmental friendliness, and excellent processability for high-frequency substrates.