A Fluorine-Containing Main-Chain Benzoxazine/Epoxy Co-Curing System with Low Dielectric Constants and High Thermal Stability

A fluorine-containing main-chain benzoxazine (BAF-M-TB) was co-cured with biphenyl epoxy for the integrated circuit industry. The benzoxazine precursor was synthesized using 4,4'-(Hexafluoroisopropylidene)diphenol (bisphenol AF), 2,2'-Dimethyl-[1,1'-biphenyl]-4,4'-Diamine(M-TB), and paraformaldehyde. In addition, the 3,3'-(Oxybis(4,1-phenylene))bis(3,4-dihydro-2H-benzo[e][1,3]oxazine) (Benoxazine ODA-BOZ), which is a commercialized benzoxazine, was co-cured with biphenyl epoxy as a control. The two co-curing systems were referred to as EP/BAF-M-TB and EP/ODA-BOZ. The curing kinetics, rheological behavior, and thermal stability of the two co-curing systems were studied. Poly-EP/BAF-M-TB and poly-EP/ODA-BOZ quartz fiber cloth reinforced composites (QFRPs) were prepared using the prepreg laminating method in order to determine their mechanical, thermal, and dielectric properties. Both of them showed good thermal properties and dielectric properties. The dielectric constant of poly-EP/BAF-M-TB QFRP is in the range of 3.25-3.54 at the low frequency of 10 kHz-10 MHz. At the high frequency of 5 GHz, its dielectric constant is 3.16, which is better than that of poly-EP/ODA-BOZ QFRP. Additionally, the Td₅ of poly-EP/BAF-M-TB was 398 °C in a nitrogen atmosphere, which is higher than that of poly-EP/ODA-BOZ.