Advances in Printed Electronics Manufacturing Featured at 2013 Flex Conference
Printed and flexible electronics increasingly offer near-term solutions to lower costs, new form factors, innovative performance features for displays, lighting, PV, batteries, sensors, and other systems. Many of the pathways for these future printed electronics devices will depend on advances in manufacturing equipment, materials and systems. The latest developments, applications, and research in printed electronics — including manufacturing technology — will be featured at the 12th annual 2013 Flexible & Printed Electronics Conference & Exhibition, to be held January 29-February 1, 2013, in Phoenix, AZ. For more information, please visit: www.flextech.org.
Anticipated growth in printed electronics has been made possible by advances conductive and printed inks, barrier films, printing and patterning systems, flexible and organic substrates, and roll-to-roll (R2R) manufacturing systems. Significant advances have been made in device patterning with feature sizes of less than 40nm can be produced on thin film layers deposited on 50 µm thick polymeric substrates. Developments have also occurred in flexible transparent and conductive films, polymer-based electronics, carbon nanotubes, multi-layer ink jet processes, polymeric substrates, and R2R deposition systems. Organized by the FlexTech Alliance, the Flex Conference attracts registrants from more than 300 companies, universities, R&D labs, and government agencies. The Flex Conference will address global technical and business issues, and advancements impacting the flexible electronics and displays value and supply chains, with sessions, short courses, exhibits, and networking events.
Among the manufacturing presentations, Northfield Automation Systems will explore process solutions related to active controlling of sensitive substrates in web format for improved yield, process monitoring, performance trending, and in-line vision feedback from lab scale to turnkey factory integration. Applied Materials will discuss a variety of different web handling and coating technologies/platforms to enable high volume R2R manufacture of thin-film based flexible photovoltaic, silicon-based TFT active matrix backplanes and touch screen devices. The work presented in their papers describes the principal challenges inherent to R2R device manufacture such as choice of substrate, thermal budget, layer stack stress, patterning, defects in addition to the strategies used to mitigate these challenges. Applied will also present results demonstrating the feasibility of R2R in both amorphous silicon and IGZO TFT backplane manufacture inclusive of device performance data, such as field effect mobility, current on-off ratio, threshold voltage and sub-threshold slope.
In order to access these developments for commercial products, current lab-scale printed devices must be scaled up to large-scale printing for mass production, which has an impact on both device design as well as materials choice. PARC will describe the design rules currently used for lab-scale, ink-jet printed multi-layer complimentary circuits and their impact on device performance and variability. In addition, an example of translating these designs to production scale equipment will be given, through PARC's partnership with the Sonoco Institute at Clemson University, with a focus on the development of gravure printed field-effect transistors.
CEA-LITEN (Laboratory for Innovation in New Energy Technologies and Nanomaterials) from Grenoble, France will show various examples of circuit blocks made in CEA by a fully printed organic-based CMOS technology, done at low temperature and compatible with large area and low cost printing processes. Air stable devices and circuits for digital, analog or RF application have been processed on flexible foils, with OTFT mobility up to 1.5cm²/V.s. Pressure, temperature and optical printed sensors processed on large area sheet (320x380mm, GEN1 size compatible) will be discussed, including an analysis of performance characteristics of circuits or the sensitivity of sensors with current processes for practical applications.
While printed silver inks have been used effectively in a variety of flexible substrate applications for over 30 years, many end user industries have historically accepted and lived with the silver ink price uncertainty that results from the fluctuating precious metal cost. However, cost-centered concerns continually invite manufacturers and users to develop innovative processes and lower cost alternatives to printed silver conductors. DuPont Electronics and Communications will discuss recent efforts to address these concerns, while specifically reviewing the performance and relative cost decreases for a new family of printed conductor materials. Additionally, DuPont review the potential benefits of applying emerging manufacturing technologies such as photonic sintering to the processing of lower cost conductors.
Other innovative materials discussed at the Flex Conference include inks based on carbon nanotube technology. Commercial interest is growing in alternatives to Indium Tin Oxide (ITO) for transparent conductive films (TCFs). Of the emerging ITO alternatives, Single Walled Carbon Nanotubes (SWNTs) show considerable promise due to their outstanding electrical, optical and mechanical properties. Commercial uptake however, has been slow because bulk quantities of material with purity levels that do not compromise optical and electrical properties are not available. In addition to purity, the length and bundle size of SWNTs have all been shown to affect the conductivity scaling of SWNT films. Linde Nanomaterials has investigated how nanotubide inks, produced from SWNTs reduced in liquid ammonia can impact the conductivity scaling factors. Reduced SWNTs spontaneously dissolve in aprotic organic solvents without the need for additional mechanical energy. This mild dissolution technique results in solutions of long, undamaged, individualized SWNTs. Using spin and spray coating deposition techniques these nanotubide inks can be deposited onto glass or PET substrates to give low resistivity at high transparency. At the lab scale, photovoltaic devices made using these TCFs have been successfully produced. The developments presented by Linde may pave the way for the mainstream use of SWNT-based in TCFs in both the touch and display markets.
According to Brewer Science, producing concentrated dispersions of carbon nanotubes often poses the difficult choice between destroying the pi-network that provides the desired electronic properties and adding surfactants that insulate the tubes from forming good conducting networks. Brewer has developed a novel method for achieving stable solutions of largely pristine carbon nanotubes without the need for surfactant. The resulting tubes can be dispersed into printable ink formulations, and the resulting coatings are highly conductive with no post-treatment. Brewer has been able to prepare formulations that are suitable for spray coating, wire-wound-rod coating, screen printing, gravure printing, and flexographic printing as well as for drop-on-demand and continuous ink-jet printers. Screen-printed coatings on polyethylene terephthalate (PET) films with sheet resistance values as low as 6 ohms/square with a single pass have been achieved. Performance data that primarily focus on roll-to-roll and other high-speed printing methods will be presented.
In addition to the above presentations, the 2013 Flexible & Printed Electronics Conference & Exhibition includes many other presentations addressing all facets of the emerging printed electronics industry. Short courses, networking events, industry awards and also part of the comprehensive event. For more information and to register, visit www.flexconference.org
December 4, 2012