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At 2014FLEX, Wide Variety of Ink Technologies Play Key Role in Growth of Flexible Electronics

By David Savastano, Editor | 02.13.14

The ink industry was well represented during these talks, as promising opportunities in conductive inks, carbon nanotubes and even graphene were topics of conversation

Flexible electronics is developing new applications and reaching new markets, but has it reached the tipping point? That is the question that 2014FLEX, organized by FlexTech Alliance, focused on during its recent conference Feb. 4-6 in Phoenix, AZ.
2014FLEX drew more than 600 attendees, more than 110 presenters and an exhibition covering the supply chain.  The ink industry was well represented during these talks, as promising opportunities in conductive inks, carbon nanotubes and even graphene were topics of conversation.
In his talk on “E Ink, Flexible and Printed Electronics, and the ‘Killer App.” Michael McCreary of E Ink said that IHS predicts that the flexible display market will reach $68 billion by 2023. He illustrated how E Ink grew once it developed technologies for eReaders, but first controlled its growth and burn rate.
“Build a sustainable business, don’t try to grow too fast, and be prepared to take quick actions if you over extend,” McCreary said. “Roll-to-roll processes are finally cost justified by the volume.”
Michael Hack, Universal Display Corporation, which makes inkjettable materials for OLEDs, analyzed “How Flexible OLED Displays Will Curve the Future,” showing opportunities in TVs, mobile phones and lighting, and highlighting the advantages of flexible OLED displays.
Alex Beavers of SRI offered insights on “Innovation in 3D Conductors for Wearable Electronics and High Density Packaging.” Beavers covered Averatek Corporation, an SRI spin-off that focuses on catalytic precursor ink technology for printed circuits, medical sensors and wearable electronics. It is utilized in additive metallization processes.
Inks were a focus of a number of talks during the 12 sessions on Wednesday, Feb. 5. Session 5: CNT Technology looked at carbon nanotubes. In “Carbon Nanotube HSE: Common Sense Meets Nanotechnology,” Robert Praino of  Chasm Technologies discussed safety procedures associated with CNTs, as well as research on work being conducted using Chasm’s V2V inks.
During “Transparent & Fully Printed CNT-based TFT Electronics,” Farzam Sajed of Aneeve Nanotechnologies showed samples made by inkjet and screen, although he added that inkjet is currecntly too slow for roll-to-roll processing.
J. Patrick Frantz of Cambridge Graphene Platform Ltd. covered “Low Cost Graphene And 2D Layered Material Inks for Printed Electronics.” He noted that graphene is five times stronger than steel, yet is stretchable, flexible and highly conductive.
“Graphene is two dimensional (2D) carbon, and it displays many unique and interesting properties. It’s often called a ‘wonder material,’” Frantz said, and noted that there has been success in roll coating and screenprinting graphene-based inks
Christopher Landorf, Brewer Science, Inc. presented a talk on “Screen-/Stencil-Printable Carbon Nanotube Inks for Conductive Trace Applications on Flexible and Stretchable Substrates.” Brewer Science has had success screen and stencil printing CNTs onto flexible and stretchable substrates.
Landorf reported that surfactant-based inks have problems for printed electronics, as surfactants insulate CNTs, reducing electrical performance. In addition, rinsing can redistribute or remove CNTs, affecting device performance and consistency, and contaminated wastewater is often generated.
“Brewer Science considers only surfactant-free inks to be viable for commercial applications,” Landorf added.
“Printing on flexible substrates is a major challenge for industry. Inks must be fundamentally flexible. Carbon nanotubes can bend easily, but the interface between tubes may break. Flexible substrates typically have a low surface energy, which makes printing with aqueous inks difficult. Transfer printing is our most successful strategy for overcoming the low surface energy of silicone substrates.”
Along those lines, in Session 6: Production of Bio-Molecules & Sensors for Bio-Marker Detection, Wu-Sheng Shih of Brewer Science, Inc. presented a talk on “CNT-based Biosensor for Sensing Metabolites (glucose, lactate, and urea) in Human Sweat. Shih reported that his company’s CNTRENE Inks have had success in screen, flexo and gravure printing as well as inkjet, drawdown bar and Aerosol Jet coating.
Session 8: Process Technology, featured a talk by Tim van Lammeren, Holst Centre/TNO, “Selective Sintering of Highly Conductive Structures on Foil.”  van Lammeren offered his thoughts developments in inkjet, rotary screen and flexo printing using sintered silver inks.
Session 15: Conductive Materials, included a talk by Henda Basti, Ecole des Mines St Etienne, who covered “Development of Copper Nano-Ink for Printed Electronics.” She offered her research on inkjet printing of the copper ink.
Session 16: Hybrid Flexible Technology, John Heitzinger of Soligie, Inc., discussed “Hybrid Manufacturing: A Path to Commercialization for Printed and Flexible Elctronics.”
“Printing is a useful manufacturing approach. Practical considerations have led us to a hybrid approach for manufacturing,” Heitzinger said. “Continued advances in flexible silicon and attach processes are beginning to bear fruit.”
The conference’s final seven sessions were held Thursday, Feb. 6.
In his talk on “Printable Alternatives to Indium Tin Oxide Films” during Session 19: Transparent Conductors, Jeff Parker, Henkel Electronic Materials LLC, talked about transparent conductive inks.
“Printable inks can replace ITO films,” Parker said. “Additive technology is significantly more cost effective vs. ITO. Printed clear conductive inks can open up new applications and markets, and will allow device manufacturing processes to be economically produced anywhere in the world.”
In Session 20: Printed Devices, Parker discussed “Positive Coefficient of Thermal Resistance Inks for Self Regulating Printed Heaters.”
“A printed heating element has a certain resistance,” Parker said. “When voltage/current is applied, power is generated. When the temperature of the circuit rises, the PTC ink starts to melt. At a certain T, an equilibrium is reached, resulting in a self regulating heater.” He added that current PTC inks are screenprintable.
Overall, Heidi Hoffman of FlexTech Alliance said that 2014FLEX was a success.
“This has been our best conference ever,” Hoffman said. “We broke records in terms of attendance with more than 600 people here. The feedback on talks has been overwhelmingly positive, and our concept of reaching the tipping point has really resonated with our attendees.”
“In terms of attendance, we are at record levels,” added Keith Rollins of DuPont Teijin Films and chairman of the board of the FlexTech Alliance. “The mix of talks here at the conference has been very interesting, ranging from the supply chain to the end user base, and the launching of our two new end users groups is a very exciting development.