Daidzein-Derived Thermosetting Resins via UV-Induced Thiol–Ene Click Reaction with Ultralow k and Tunable Mechanical Properties for Electronic Packaging

The exploration of biomass-derived thermosetting resins for implementation in flexible electronic packaging has emerged as a central focus. Herein, a daidzein-derived monomer (DDAB) was synthesized, which featured carbon–carbon double bonds. Biobased resins, namely, DDAB/3SH and DDAB/4SH, were meticulously fabricated via photocuring process, entailing the amalgamation of DDAB with trithiol (TPTMP) and tetrathiol (PETMP) monomers, respectively. DDAB/4SH showed impressive mechanical properties with a tensile strength of 28.1 MPa and elongation at break of 21.3%. Notably, owing to the augmented free volume inherent within the system, DDAB/3SH exhibited an exceptional elongation at a break of 111.7%, thereby surpassing the performance metrics of the majority of previously documented thiol-containing compounds. Moreover, both DDAB/3SH and DDAB/4SH demonstrated desirable dielectric properties. Specifically, within the frequency range of 15–16 GHz, DDAB/3SH achieved a minimum dielectric constant of 2.58. The exceptional dielectric performance, coupled with the tunable mechanical properties, proves the substantial application potential of DDAB/SH biomass-derived resins for flexible electronic packaging applications.