Synergistic Effect of Fluorination and Molecular Orientational Order on the Dielectric Properties of Low-κ Liquid Crystal Polymer Films

Abstract

With the rapid advancement in 5G and 6G communication technology, the demand for fast transmission and reception speed, high-capacity communication, and simultaneous multiterminal access without delay has become extremely important. Here, we fabricated liquid crystal polymer (LCP) films by judiciously controlling fluorine contents and the degree of orientational order. LCPs with fluorinated additives have garnered significant attention due to low dielectric properties and low moisture uptake compared to the current polymeric materials like polyimide, thereby anticipating to minimize signal loss in the high-frequency band of 28 GHz. The optimum fluorine content is determined under a low loading condition of 2.0 wt %. More fluorine can lead to a sharp decline in orientational order and deteriorate the dielectric properties. Similarly, the rubbing process renders uniaxially aligned molecules, which induce low dielectric loss due to the restricted chain motions upon polymerization. Additionally, theoretical values obtained from DFT calculations provide fundamental insights into understanding the relationship between fluorine moieties and dielectric properties.