Technical Abstracts
In Case You Missed It
Additive Technologies
“Process Capability of Aerosol-Jet Additive Processes for Long-Runs up to 10-Hours”

Authors: Pradeep Lall, Ph.D, Amrit Abrol, Nakul Kothari, Ben Leever and Scott Miller; lall@auburn.edu.

Abstract: Aerosol Jet supports a variety of materials, including nanoparticle inks and screen-printing pastes, conductive polymers, insulators, adhesives, and even biological matter. Adoption of additive manufacturing for high-volume commercial fabrication requires an understanding of the print consistency and electrical and mechanical properties. Little literature exists that addresses the effect of varying sintering time and temperature on the shear strength and resistivity of the printed lines. In this study, the effect of process parameters on the resultant line-consistency, mechanical and electrical properties is studied. Print process parameters studied include the sheath rate, mass flow rate, nozzle size, substrate temperature and chiller temperature. Properties include resistance and shear load to failure of the printed electrical line as a function of varying sintering time and varying sintering temperature. Aerosol Jet was used to print interconnects. Printed samples were exposed to different sintering times and temperatures. The resistance and shear load to failure of the printed lines was measured. The underlying physics of the resultant trend was then investigated using elemental analysis and SEM. The effect of line-consistency drift over prolonged runtimes has been measured for up to 10hr. of runtime. Printing process efficiency has been gauged a function of process capability index (Cpk) and process capability ratio (Cp). Printed samples were studied offline using optical profilometry to analyze the consistency within the line width, line height, line resistance and shear load to study the variance in electrical and mechanical properties over time. (ASME International Technical Conference and Exhibition on Packaging and Integration of Electronic and Photonic Microsystems, October 2019)

Materials Science
“Radiophysicists Study the Properties of Composites for 5G devices”

Authors: Tomsk State University

Abstract: TSU radiophysicists are forming a database of properties of composite materials, which can be used to create devices with 5G and space communication devices operating in the terahertz range. The scientists are creating composite materials from ABS plastic and nanotubes and measuring their properties in a frequency range from 10MHz to 1THz. To create the source material, the radiophysicists are using polymers and, aided by chemical treatment, filling them with carbon nanotubes, which the Boreskov Institute of Catalysis of the Siberian Branch of the Russian Academy of Sciences produces for the Terahertz Laboratory of the Faculty of Radiophysics. By adding nanotubes of different concentrations, the electrophysical properties of the material are changed; for example, the dielectric constant is increased. Then, using 3-D technology, a printed circuit board with elements (conductors, resistors, and others) can be created. From the material obtained on a 3-D printer, a control sample is printed – plates or rings, depending on the standard of the measuring installation, and the properties of the composite in the terahertz range are examined. Properties of 50 samples in the radioactive range up to 1THz have been studied. (Tomsk State University website, Dec. 9, 2019, en.tsu.ru/news/radiophysicists-study-the-properties-of-composites-for-5g-devices/)

RF Antennas
“Two-Dimensional Metallic Niobium Diselenide for Sub-Micrometer-Thin Antennas in Wireless Communication Systems”

Authors: Girish Sambhaji Gund, Min Gyu Jung, Keun-Young Shin and Ho Seok Park.

Abstract: State-of-the-art Internet of things (IoT) and smart electronics demand advances in thin and flexible radio frequency (RF) antennas for wireless communication systems. So far, nanostructured materials such as metals, carbon nanotubes, graphene, MXene, and conducting polymers have been investigated due to their noteworthy electrical conductivity. However, most antennas based on metallic materials are thick, which limits their application in miniaturized and portable electronic devices. Herein, the authors report 2-D metallic niobium diselenide (NbSe2) for a monopole patch RF antenna, which functions effectively despite its sub-micrometer thickness, which is less than the skin depths of other metals. The as-fabricated antenna has an 855nm thickness and a 1.2Ωsq–1 sheet resistance and achieves a reflection coefficient of −46.5dB, a radiation efficiency of 70.6%, and omnidirectional RF propagation. Additionally, the resonance frequency of this antenna at the same thickness is reconfigured from 2.01 to 2.80GHz, while decreasing its length and preserving its reflection coefficient of less than −10dB. This approach offers a facile process to synthesize 2-D metallic transition metal dichalcogenides for the rational design of flexible, miniaturized, frequency-tunable, and omnidirectional monopole patch RF antennas for body-centric wearable communication systems. (ACS Nano, November 2019, pubs.acs.org/doi/10.1021/acsnano.9b06732)

This column provides abstracts from recent industry conferences and company white papers. Our goal is to provide an added opportunity for readers to keep abreast of technology and business trends.