Strategy to achieve low-dielectric-constant for benzoxazine-phthalonitriles: introduction of 2,2'-bis[4-(4-Maleimidephen-oxy)phenyl)]propane by in-situ polymerization

Abstract

With the upgrading demand of high-frequency and high-speed communication field, it is imperative to develop low dielectric constant (Low-k) materials with higher temperature resistance. In the study, the thermosetting bi-functional benzoxazine-phthalonitrile bearing pendant allyl groups (Boz-ph) was modified with the 2,2'-bis[4-(4-Maleimidephen-oxy)phenyl)]propane (BMI-80). Specifically, the BMI-80 was reacted with the pendant allyl groups of Boz-ph by in-situ polymerization, and a series of high-performance Boz-ph/BMI-80 resins were synthesized. The effect of different proportions of Boz-ph/BMI-80 resins on the curing behavior, thermal stability, mechanical and dielectric properties was investigated. With the introduction of BMI-80, the microstructure of cured Boz-ph/BMI-80 resins was changed from brittle fracture to ductile fracture. Compared with pure Boz-ph (70.1 MPa), the flexural strength of Boz-ph/BMI-80-100% is up to their maximums of 102.8 MPa. Moreover, the Boz-ph/BMI-80 resins showed high glass transition temperature (T_g=325~333℃), low water absorption (less than 2.5%) and good dielectric properties. The dielectric properties improved with the increase of BMI-80 content, and the dielectric constant and dielectric loss of Boz-ph/BMI-80-100% were 3.51 and 0.008 (at 10 MHz). This work suggested that the Boz-ph/BMI-80 resins had great potential to be used as the matrix of the high-temperature and high-frequency copper-clad laminates.