Materials containing benzocyclobutene units with low dielectric constant and good thermostability prepared from star‐shaped molecules

ABSTRACT With the development of ultralarge‐scale integrated circuits, polymers with low dielectric constant and high thermal stability have aroused great interest. We prepared two novel bridged siloxane‐based benzocyclobutene (BCB) star‐shaped monomers, tetrakis[dimethyl siloxy‐4‐(1′,1′‐dimethyl‐1′‐ethyl silicon)‐benzocyclobutene] (TDSDES‐BCB) and tetrakis(hexamethyl siloxane vinyl‐benzocyclobutene) (THSV‐BCB), and the corresponding resins were obtained by curing. The structures of TDSDES‐BCB and THSV‐BCB were confirmed by 1 H‐NMR, 13 C‐NMR, and 29 Si‐NMR spectra and time‐of‐flight mass spectrometry analysis. The curing behavior of these monomers was investigated by Fourier transform infrared spectroscopy and differential scanning calorimetry. The dielectric constant of cured TDSDES‐BCB is only 2.43 at 10 MHz (that of THSV‐BCB is 2.46). In addition, these resins display high thermal stability: the 5 wt % weight loss temperature of cured TDSDES‐BCB is about 467 °C (454 °C for THSV‐BCB resin). The excellent low dielectric property is attributable to the free volume created by the star‐shaped structure and crosslinked network structure of BCB after curing. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136 , 47458.