Branched Anhydride‐Modified Epoxy Laminates: Synergistic Improvement of Dielectric and Thermal Properties

A novel branched anhydride curing agent was synthesized to simultaneously enhance thermal properties and dielectric properties of epoxy laminates for overcoming the traditional performance trade‐off. The novel branched rigid ternary anhydride curing agent (TBA, TDI‐BTDA Anhydride) was synthesized in a one‐step process from toluene diisocyanate trimer (TDI trimer) and 3,3′,4,4′‐diphenyl ketone tetracarboxylic dianhydride (BTDA). Using TBA‐modified epoxy resin (EP) as the matrix resin, a novel laminate was successfully prepared. Dynamic mechanical analysis (DMA) results showed that the glass transition temperature (T g ) of the TBA‐modified EP laminate increased from 170°C to 213°C. The glass transition temperature of EP laminates was significantly increased, reflecting their good thermal stability. Dielectric property test results indicate that at 10 6 Hz, the dielectric constant decreased from 4.58 to 3.78, and the dielectric loss decreased from 0.0105 to 0.00235. The introduction of TBA effectively increased the free volume fraction (FFV) of the system, thereby significantly reducing the dielectric constant and dielectric loss of the laminate. Additionally, the results of insulation and mechanical property tests indicate that this new laminate exhibits excellent comprehensive performance, with all indicators meeting the requirements for electronic‐grade copper‐clad laminates.