Ultralow Dielectric Loss in a High-Frequency and Strong-Adhesion Hydrocarbon Resin Film by Introducing Interfacial Oxygen-Containing Groups and a Microporous Aerogel

Next-generation high-frequency and high-speed telecommunications require printed circuit boards with low dielectric loss and reliable interfacial adhesion to ensure efficient signal transmission and structural integrity. However, the interfacial delamination between copper foils and dielectric substrates remains a critical failure mode. Herein, silica aerogel (SA) fillers were incorporated into graft-modified polybutadiene (g-PB) to form composite films (g-PB/SA), which were subsequently treated with low-pressure plasma technology to achieve high peel strength, a low dielectric constant, and an ultralow dielectric loss. The SA content was evaluated, and a moderate filler loading of 20 wt % was selected for the subsequent plasma-treatment study. Among the investigated plasma atmospheres of Ar, CF4, and O2, O2 plasma produced the most pronounced improvement in surface wettability and interfacial adhesion and was therefore selected for further process optimization. The surface of g-PB/SA adhesive films was modified using O2 plasma so as to introduce oxygen-containing functional groups such as −OH and −C–O– with dipole moments of 1.30–1.69 D, and the optimal process parameters were determined to be 90 s exposure time, 100 W RF power, and 30 Pa oxygen pressure. Consequently, the interfacial peel strength was increased to 0.862 N/mm. Moreover, after modification with silica aerogel particle fillers, the adhesive film maintained a low dielectric constant (Dk = 2.73) and dissipation factor (Df = 0.0027) at 10 GHz. The plasma treatment and aerogel filling provided an effective approach to fabricate high-performance adhesive film materials for high-frequency communication, effectively overcoming the inherent trade-off between strong adhesion and low dielectric loss.