Microwave dielectric characterization of flexible plastic films using printed electronics

This work describes the development of a wideband RF measurement technique using printed test structures for characterizing the complex dielectric properties of flexible substrates at RF and microwave frequencies. This novel method is based on a single probe measurement using two concentric circular capacitors with different gap sizes that can be additively manufactured on the dielectric film under test. Three types of common, commercially-available substrates for flexible electronics were characterized: Polyimide (Kapton), Liquid Crystalline Polymer (LCP), and Polyethylene Terephthalate (PET). Their dielectric constant and loss tangent were measured from 50MHz up to 20GHz, and were compared to the data available from substrate vendors.