Terahertz Dielectric Property Characterization of Photopolymers for Additive Manufacturing

Abstract

In this paper, resin-based photocurable polymer materials for stereolithography, digitallight-processing (DLP), and polymer-jetting additive manufacturing techniques were characterized from 0.2 to 1.4 terahertz (THz) for their comprehensive dielectric properties, e.g., refractive index, absorption coefficient, dielectric constant, and loss tangent, by using laser-based THz time-domain spectroscopy. A total of 14 photocurable 3D-printing polymers were chosen, owing to their suitability, in terms of printing resolution, material characteristics, and so on, for millimeter-wave (mm-wave) and THz applications. The measurement results from 0.2 to 1.4THz, the dielectric constants of all photopolymer samples under test are between 2.00-3.10, while the loss tangents are from 0.008 to 0.102, which are quite useful for many applications, e.g., 3D printed antennas and THz transmission lines, which were demonstrated by an asymptotically quasi-single-mode Bragg fiber microfabricated by DLP micromanufacturing technique using HTM140-V2 photopolymer, which is previously reported at the nominal frequencies from 0.246 to 0.276 THz.

Microwave Characterization of Low-Loss FDM 3-D Printed ABS With Dielectric-Filled Metal-Pipe Rectangular Waveguide Spectroscopy

“…Nevertheless, an attempt to accurately characterize 3-D printed photopolymers using THz TDS has been recently reported [34]. For example, results from [34] for photopolymer ABS samples are given in TABLE 9, when 3-D printed using either polymer-jetting (Polyjet) or digital-light processing (DLP); both being more advanced additive manufacturing techniques when compared to FDM 3-D printing of ABS thermoplastic filaments [4].…”

“…TM modes in lossless waveguides (34) From (27), it will be found that for the TE m0 mode at the lowest-order Fabry-Pérot resonance frequency,…”

Gradient-Index-Based Frequency-Coded Retroreflective Lenses for mm-Wave Indoor Localization

“…However, it is hard to realize such structures at mm-waves above 80 GHz because of the xy resolution limit of the conventional 3D printers for reliable printing (FDM ≈ 0.4 mm depending on the print nozzle diameter [35], SLA ≈ 0.15 mm depending on the laser spot size [36]), and the requirement for supporting structures, which are too difficult to remove. Further, a higher permittivity (εr > 2.5) and dielectric losses (tan δ > 0.02) of the materials used in additive manufacturing makes this method inappropriate [37][38][39].…”

Three‐dimensional printing technologies for terahertz applications: A review

“…Cyclic olefin copolymer (TOPAS) and high density polyethylene (HDPE), which are nonstandard FDM‐printed materials, show lower refractive indices and ultra small absorption coefficients (~0 cm −1 ) below 0.5 THz. In addition to these FDM‐printable materials, Duangrit et al has characterized some resin‐based photocurable polymer materials for SLA, DLP, and PolyJet techniques between 0.2 and 1.4 THz, and are also summarized in Table , using the THz time‐domain spectroscopic technique, with their refractive index and absorption from 1.59 to 1.68 cm −1 , and 1.5 to 16.9 cm −1 , respectively.…”