Synergistic Effects of Bio‐Based Benzoxazine/Epoxy Blends for Copper‐Clad Laminates With Low Dielectric Performance

ABSTRACT To develop low dielectric materials in high‐frequency, high‐speed copper‐clad laminates (CCLs), furfuryl tertiary phenolic benzoxazine (FPBZ) was synthesized by Mannich condensation reaction using bio‐based furfurylamine, p‐tert‐butylphenol, and paraformaldehyde. The results show that FPBZ resin exhibits excellent dielectric properties ( D k = 2.21, D f = 0.0049 at 1 MHz), but it is brittle and has a high curing temperature. To overcome these limitations, epoxy resin and 2‐methylimidazole (2‐MIM) were introduced to prepare FPBZ/epoxy blends. Differential scanning calorimetry analysis revealed that FPBZ/epoxy/2‐MIM blends exhibited double peaks. With an increase in epoxy content from 25% to 50%, the activation energy of Peak A decreased from 75.5 to 61.9 kJ/mol, while that of Peak B increased from 126.8 to 131.4 kJ/mol. Mechanical tests demonstrated that the toughness of FPBZ was improved by the addition of epoxy, with an impact strength reaching 7.4 kJ/m 2 . CCL performance tests indicated that FPBZ/epoxy‐33% based CCL exhibited the most balanced properties, featuring a dielectric constant (2.88) and loss (0.0074), peel strength (1.38 N/mm) and glass transition temperature (158.4°C), which meet the requirements for high‐frequency CCLs. This study demonstrates that the FPBZ/epoxy blend balances mechanical and dielectric performance through a covalently crosslinked network, providing a novel strategy for developing high‐performance CCLs.