Broadband Millimeter-Wave Dielectric Properties of Liquid Crystal Polymer Materials

• Published in: IEEE transactions on components, packaging, and manufacturing technology (2011) packaging, and manufacturing technology (2011), 2022-01, Vol.12 (1), p.192-194
• Main Authors: Mcgarry, Michael P., Iyer, Mahadevan K., Lee, Mark
• Format: Article
• Language: English
• Subjects: Broadband; Dielectric properties; Dielectrics; Dispersion; Dissipation factor; Frequency measurement; Integrated circuit (IC) packaging; Integrated circuit modeling; Integrated circuits; Liquid crystal polymers; Liquid crystals; Mechanical properties; Microwave circuits; Microwave frequencies; millimeter (mm)-wave; Millimeter waves; mm-wave ICs (MIMICs); Packaging; Radio frequency; Semiconductor device measurement
• ISSN: 2156-3950; 2156-3985
• DOI: 10.1109/TCPMT.2021.3131921

Liquid crystal polymers (LCPs) are a class of thermoplastic polymers widely used for packaging radio frequency (RF), microwave, and low millimeter (mm)-wave integrated circuits operating at frequencies as high as 77 GHz. Because of their relatively low cost and attractive electrical, thermal, and mechanical properties, LCPs are of potential interest as a packaging material for advanced circuits operating at high mm-wave frequencies, ~100-300 GHz. To potentially use LCPs at these frequencies will require a quantitative knowledge of the materials' dielectric properties across a broad frequency band. Here, we present nondestructive measurements of the dielectric constant, Dk , and dissipation factor, Df , on six commercially made LCP materials now used for packaging RF/microwave circuits. Measurements using phase-sensitive transmission from 140 to 220 GHz show values of Dk ranging between 2.0 and 4.5, with four materials essentially nondispersive but two showing significant dispersion in this band. Df values were in the range 0.01-0.06, substantially higher than that has been reported for many LCP materials at RF/microwave frequencies. The results are useful to model accurately the performance of packaged mm-wave circuits.