Tailored Interfacial sp ² /sp ³ Hybridization in Diamond@DLC Heterostructure: Resolving the Microwave Absorption-Dielectric-Thermal Trilemma in Epoxy Composites for Electronic Packaging

With the increasing operational frequencies and miniaturization of electronic devices and integrated circuits, epoxy (EP) composites for electronic packaging face the challenge of achieving multifunctional performance requirements, including microwave absorption, superior thermal conductivity (TC), and high dielectric strength. This work develops a novel strategy of tailoring the interfacial sp 2 /sp 3 hybridization ratio to resolve the trilemma among multifunctional performance enhancements. Leveraging the intrinsic high TC and dielectric strength of diamond, combined with the tunable sp 2 /sp 3 -hybridized structure of diamond-like carbon (DLC), the fabricated Diamond@DLC/EP composites exhibit outstanding multifunctional performance. The high sp 2 /sp 3 hybridization ratio structure enhances impedance matching and interfacial charge dissipation, resulting in a minimum reflection loss of −26.66 dB and an effective absorption bandwidth of 6.1 GHz for composites. Concurrently, the tailored sp 2 /sp 3 -hybridized structure endows the filler–matrix interface with a more gradual modulus gradient transition and reduced interfacial thermal resistance. Through the mitigation of interfacial defects and the reduction of phonon scattering, the composites achieve a breakdown strength of 66.71 V·μm –1 and an enhanced TC of 1.15 W·m –1 ·K –1 . This approach of tailoring the interfacial sp 2 /sp 3 -hybridized structure for the synergistic enhancement of multiple properties presents a promising design strategy for next-generation electronic packaging materials.