Low Dielectric Adhesive through Thiol-Ene Click-Reaction for High-Frequency Electronic Devices

With the continuous growth of 5G communication-based high-speed transmission-reception systems, there is a demand for developing a low dielectric material in high-frequency electronic devices. Since the 5G communication system uses a shorter wavelength than the 4G mobile communication, there is a problem with transmission loss because the rate of absorption by materials during the movement of radio waves is high. For this reason, electronic components such as FCCL for 5G mobile communication must exhibit a low dielectric character to reduce transmission loss. Herein, we proposed a fabrication of a low dielectric adhesive through a thiol-ene click reaction between bismaleimide and multifunctional thiol, applicable to advanced electronic devices for 5G communication. The development of the adhesive with a low dielectric constant at a high-frequency range is indispensable while maintaining high adhesion between a copper foil and a low dielectric polymer sheet. We optimized the composition of the adhesive by controlling the ratios of the compounds with alkene or thiol groups. The dielectric constant (ε') measured at 10 GHz ranged from 2.6 to 2.7, which is lower than commercially available adhesives. The peel strength of the low dielectric bond was measured as 1.0 N/mm through a 90° peel test, showing strong adhesion properties between the copper foil and the low dielectric polymer sheet. This low dielectric adhesive could be applied to manufacturing technology of advanced electronic devices for 5G communication in semiconductors, automobiles, mobile phones, and robots.