FLEX/MSTC 2020 Focuses on New Applications, Opportunities for FHE
By David Savastano, Editor | 03.03.20
Presenters highlight the latest developments, research in the world of flexible hybrid electronics and sensors.
Carmelo Sansone, SEMI’s MEMS and Sensors Industry Group (MSIG) director, said the MSTC conference provided attendees with excellent insights.
“The keynote speakers did a good job in putting the spotlight in the intersect between MEMS and sensors and flexible technology,” Sansone said. The lab to fab stories session, which included the talk from Thomas Kenn from Stanford University on encapsulated MEMS – Clocks and Inertial Sensors, was spot on, especially considering we are in the process of rolling out the R&D PNT program. The VC investors and startups session was great. The fast-paced format and the questions that came from the VC panels and the audience were over the top.”
Feb. 26 Concurrent Sessions
As the FLEX/MSTC 2020 conference moved into its final day on April 26, attendees had a wealth of sessions and speakers to select. There were four concurrent sessions to choose from, including sensors, displays, printing, inks and manufacturing, and the presenters offered plenty of insights into the field of flexible and hybrid electronics.
The Substrates & Barriers session began with a talk by Takatoshi Abe, technology research manager for Panasonic, who discussed “Stretchable Materials for Hybrid Electronics Based on a Novel Thermosetting Polymer System.” Abe noted that typically PCB circuits aren’t stretchable.
“Our stretchable film is based on a thermosetting polymer solution developed by Panasonic R&D,” said Abe. “It is designed for stretchable circuits. It also has high temperature resistance. We’ve created sensor systems organized by using basic process of PCB assembly using our stretchable film. The materials have good heat and chemical resistance.”
Joey Mead, interim associate dean for graduate studies, University of Massachusetts, Lowell, followed with “Novel Substrate Manufacturing for Stretchable Printed Electronics.”
Mead pointed out that there are two classes of polymers: plastics and elastomers, which come in thermoset and thermoplastic elastomers (TPEs).
“We are looking to make something that is stretchable,” Mead reported. “Applications include medical apps and wearable devices for soldiers. We looked at needing a stretchable ink, which we have ideas on. If the screen ink isn’t stretchable, it doesn’t matter how stretchable the substrate is. The substrate should be compatible with roll-to-roll printing, and butyl rubber has good potential as a substrate.”
The Power session featured Pradeep Lall, MacFarlane Endowed distinguished professor and director at Auburn University. Lall focused his talk on “Assessment of Flexible Batteries Under Dynamic Folding and Flex-to-Install with Varying C-Rates and Temperatures.”
“There are deficiencies in testing models, such as folding and stretching of batteries,” Lall observed. “As the battery degrades, it discharges faster. Depth of charge is important. Higher operating temperatures improves battery life, and mild flexing also improves battery life. With higher depth of charge, the amount of LI-ion transport into the battery increases.”
Neil Bolding, technical manager, MacDermid Enthone, offered his insights into “Seamless Integration of Automotive Displays” during the Displays & Optoelectronics II session.
“Ten years ago, did you have a display in your car? Now all cars have them,” said Bolding. “Technology introduction is becoming more and more common. How do we integrate that into design? Car interiors have evolved over the years, and the future of car interiors is for a sleek, seamless look with touchscreens and displays positioned throughout the cockpit.”
Bolding noted that MacDermid Alpha’s XtraForm process uses screenprinting and UV curing, and is also lightweight, reducing manufacturing cost.
In the Sensors session, University of Rhode Island professor Gregory Otto covered “Low Power Sensors for Trace Detection of Threats in the Vapor Phase.” Otto discussed fabrication of thin film sensors on ultrathin YSZ substrates, which allows for continued reduction in thermal mass without sacrificing catalytic surface area.
“Microheaters fabricated on the YSZ substrate show extremely localized heating and rapid cooling. Results show significantly improved sensitivity and response time at reduced operating temperatures and power requirements,” Otto noted.
The Printing Technologies session featured Dr. Reinhard R. Baumann, professor emeritus, TU Chemnitz, who discussed “Printing Beyond Color—The Potential of Inkjet Technology in General Manufacturing Environments for Printed Electronics.” Dr. Bauman noted that printing is a highly productive manufacturing technology.
“Printing is a continuously manufacturing technology, regularly carried out under ambient conditions,” said Dr. Baumann. “The market trend is for a growing variety of products at decreasing batch sizes and highly efficient use of functional materials. Individualizing mass products in one production line is not easy. We developed a lighthouse project with Fraunhofer to think about that approach. We are doing inkjet printing on 3D surfaces. For a smart car door, where you do the printing before forming, the secret is in the inks.”
Carolyn Ellinger, GM, printed electronics VP, Kodak PE Tech, LLC, Aa subsidiary of Eastman Kodak Company, followed Dr. Baumann’s talk with “Advantages and Challenges of High-Resolution Flexography for Flexible Electronics.” Ellinger noted that the core of Kodak’s functional printing business is high-resolution flexography.
“You can improve transparency by printing finer lines,” Ellinger added.
Xiangyang Liu, research council officer, National Research Council Canada, closed the Printing Technologies session with “Versatile Molecular Ink Platforms for Printed Electronics.” Liu discussed the NRC’s silver molecular ink.
“We use our silver molecular ink to produce all-printed capacitors with very good properties,” Liu reported. “The conductive tracks are also compatible with flip chips and silver epoxy.”
In the Reliability—Characterization session, Benjamin Stewart, graduate research assistant, Georgia Institute of Technology, discussed “Biaxial Inflation Stretch (BIS) Test for Printed Electronics.”
“Uniaxial test typically goes to much higher percentage elongation to achieve high resistance,” Stewart observed. “In an equibiaxial test, 5% strain could result in 1000% change in electrical resistance. This is because the particles are pulled apart in both directions. The BIS test is simple and versatile and inexpensive.”
The State of the Art FHE Manufacturing session covered a variety of topics. Enid Kivuti, technology director, Sheldahl, A Flex Company, discussed “Print.”
“FHE is intrinsically amenable to the changing needs of the electronics landscape,” Kivuti observed. “In mass production, we want to be cost effective and reliable to ensure the consumer experience. Flexo printing is good for fine printing like metal mesh. Aerosol Jet’s advantage is that you can have fine printing. Screenprinting is the most commonly used printing technology. You can do multilayer buildup with screen. You have to pick your technology for a given application – sheet, roll or 3D; substrate type; ease of validation; number of layers; feature size; and at the end, cost of ownership. If you’re not coming from an electronics background it can be challenging.”
Weifeng Liu, technologist/manager for Flex, analyzed “Encapsulation/Over Molding.”
“FHE systems may be more susceptible to damages caused by the manufacturing process,” Liu said. “PET has a lower withstanding temperature compared to polyamide. Encapsulation needs to serve as a good environment barrier and have good binding with the base substrate. Scalability to mass production is essential. We have to leverage existing encapsulation technologies to optimize for FHE applications.”