Application of Multi-Vinyl Silicon-Containing Cross-Linkers in Free-Radical Cross-Linked Thermosets with Ultra-Low Dielectric Loss

Ultralow-loss thermosetting resins cured via free-radical polymerization have been extensively applied as the polymeric matrix in high-frequency and high-speed printed circuit boards and electronic packaging substrates. In recent years, silicon doping has been commonly acknowledged for its potential to reduce the dielectric loss of materials. Three silicon-containing cross-linkers are investigated in this work for use in ultralow-loss thermosetting poly(phenylene oxide) (PPO) materials. The study compares the influence of these silicon-containing cross-linkers with two commercially available cross-linkers, focusing on their effects on curing temperature, dielectric properties, thermal characteristics, moisture resistance, and aging resistance. Silicon-containing cross-linkers showed appropriate reaction temperatures that were comparable to that of conventional epoxy materials. More importantly, they decreased the dielectric loss of cured samples with the lowest dissipation factor (Df) value of 0.00159 at 10 GHz. The addition of silicon atoms also slowed the deterioration of dielectric properties during high-temperature aging experiments and reduced moisture absorption in PPO samples. However, there are also concerns regarding the reduction in the glass-transition temperature and the increase in the coefficient of thermal expansion. These results demonstrate the promising potential of silicon-containing cross-linkers in enhancing the performance of ultralow-loss PPO materials for advanced electronic packaging applications.