Characterization of Liquid Crystal Polymer (LCP) Material and Transmission Lines on LCP Substrates From 30 to 110 GHz

TLDR

Liquid crystal polymer (LCP) has emerged as a promising high‑performance microwave substrate and packaging material. This study investigates the electrical properties of LCP at millimeter‑wave frequencies using multiple measurement techniques. The authors measured dielectric constant and loss tangent above 30 GHz with microstrip ring and cavity resonators, and fabricated transmission lines on LCP substrates of varying thicknesses to report loss per centimeter from 2 to 110 GHz. The dielectric constant remains steady near 3.16 with a loss tangent below 0.0049, while peak transmission‑line losses at 110 GHz range from 0.88 to 2.55 dB/cm, demonstrating LCP’s excellent dielectric performance across millimeter‑wave bands.

Abstract

Liquid crystal polymer (LCP) is a material that has gained attention as a potential high-performance microwave substrate and packaging material. This investigation uses several methods to determine the electrical properties of LCP for millimeter-wave frequencies. Microstrip ring resonators and cavity resonators are measured in order to characterize the dielectric constant (/spl epsi//sub r/) and loss tangent (tan/spl delta/) of LCP above 30 GHz. The measured dielectric constant is shown to be steady near 3.16, and the loss tangent stays below 0.0049. In addition, various transmission lines are fabricated on different LCP substrate thicknesses and the loss characteristics are given in decibels per centimeter from 2 to 110 GHz. Peak transmission-line losses at 110 GHz vary between 0.88-2.55 dB/cm, depending on the line type and geometry. These results show, for the first time, that LCP has excellent dielectric properties for applications extending through millimeter-wave frequencies.