Nondestructive dielectric measurement method for orientation distribution of liquid crystal polymers film

Abstract

Liquid crystal polymers (LCP) are widely used materials in 5G applications. The LCP films easily tend to form an uneven orientation distribution that degrades their service properties. However, tailoring its orientation distribution remains a challenge, primarily because traditional measurement methods are unable to non-destructively measure the orientation distribution of large-area LCP films attributed to penetration depth constraints or sample preparation requirements. Capitalizing on its inherent orientation-induced dielectric anisotropy, we propose a nondestructive dielectric measurement method for the orientation distribution of LCP film using an interdigital electrodes array. Compared to polarized FTIR and WAXS/SAXS, the dielectric method provides a universally applicable solution, even in intricate scenarios like regions with wrinkles in LCP films, films with substantial thickness, and those lacking large-scale structures. Moreover, the accurate measurement of orientation distribution confirms that the large surface roughness and significant variations in thickness distribution are attributed to the uneven orientation distribution. The findings provide a “visual window” for precisely tailoring the orientation structure of LCP films for 5G applications and beyond.