Fluorinated Phthalonitrile Resin with Excellent Thermal Stability and Low Dielectric Constant for High‐Frequency Electronic Packaging

Abstract Phthalonitrile (PN) resin promising material for preparing high‐speed and high‐frequency electronic packaging because of its unique hightemperature resistance and excellent insulation performance. A fluorinated PN oligomer (4,4’‐bis (p‐perfluoro‐phenol‐(bis(p‐phenol)perflouoropropane‐2,2‐diyl)‐p‐oxy‐diphthalonitrile) (PFDP)) containing trifluoromethyl and decafluorobiphenyl groups are designed, synthesized, and characterized. The oligomer is blended with 4‐(aminophenoxy) phthalonitrile (APPH), and then cured into polymers under the temperature‐programmed process. The reactive blend has good processability, and structures of isoindole, triazine ring, and phthalocyanine ring are found in the curing reactions. The fluorinated PN (P‐380) shows outstanding thermal stability and mechanical properties (5% thermal degradation temperature: 518 °C (N₂); 516 (Air), T_{Heat‐resistance index}: 268 °C, activation energy of thermal decomposition: 334.89 kJ mol⁻¹, glass transition temperature (Tg) > 400 °C). Meanwhile, the fluorinated PN simultaneously exhibited a superior low dielectric constant (D_k, 2.21) and dielectric loss (D_f, 0.01) at 10 GHz. Moreover, the water absorption of the resin is as low as 0.74%, which meets the requirement of dielectric materials. These results would strongly suggest such PFDP PN resin as excellent packaging materials in those high‐tech applications such as aerospace and communication electronic devices.