There continues to be growing interest in the fields of printed electronics (PE) and RFID, as companies develop innovative approaches for integrating these products into new applications. Still, there remain many challenges ahead.
Photo courtesy of PolyIC GmbH.
All things considered, there are gains being made, as more manufacturers are preparing to move ahead into production. Leaders in the field of conductive inks say that interest in PE is increasing.
“We still see a lot of early interest and curiosity to be sure, but we are also seeing more organizations with genuine programs in place taking advantage of what they see as the versatility and operational simplicity of conductive ink solutions,” said Stan Farnsworth, vice president of marketing for NovaCentrix.
Indeed, the conductive inks are critical to the overall success of the PE application.
“The printed electronics market, particularly OLED lighting and displays as well as organic photovoltaics, requires solution-processed conductive inks to realize performance and cost improvements,” said Mary Boone, Plextronics’ director, inks business. “Electrode, hole injection, and electron transport are all functions of conductive inks in these growing applications.”
“The market for conductive inks is expanding both within market segments and with additional segments,” said David Wald, senior manager, business development at International Imaging Materials, Inc. (IIMAK). “The ability to dramatically improve existing designs and to offer alternatives for solutions for ideas once thought of as futuristic is too much to ignore. New materials are allowing conductive inks to become even more cost effective, allowing for increased production efficiencies and lower material costs.”
Yu Adachi, corporate communications for Toyo Ink Co. Mfg., Ltd., said that at present, the RFID market is limited in use to applications such as materials management at production sites, exhibition admission tickets and book tracking at libraries.
“Regrettably, the technology has yet to take off as initially expected,” Adachi added. “Proof testing of printed electronics products, however, had showed a steady increase in growth. On the other hand, the field of printed electronics has made headway in the areas of increased production efficiency, cost reductions and environmental benefits arising from non-etching methods of circuit fabrication.
Sun Chemical’s state-of-the-art 3,000 square foot cleanroom in Carlstadt, NJ. (Photo courtesy of Sun Chemical)
Wolfgang Mildner, managing director of PolyIC GmbH, and chairman of Organic Electronics Association (OE-A), said that the markets for PE and RFID are pretty distinct in their dynamics right now. “PolyIC sees very interesting applications and growing markets for conductive structures,” Mildner said. “For example in the area of touch sensors, displays, electric heating elements ... These conductive structures can be used as an ITO replacement.
“Our impression is that applications for RFID are also still expanding despite a reduced dynamic last year,” Mildner added. “They seem to stall a bit because of restricted budgets related to the global economic crisis.”
The Global Recession
And Printed Electronics
The recession has impacted virtually all industries, and PE and RFID also felt the downturn. However, there were also opportunities.
“It is true that budgets and spending have been tightened, but it is also true that the economic stress has encouraged technology and product teams to look for new paths forward,” Farnsworth said. “We continue to see a flood of new interest as well as companies continuing forward with their programs. The progress towards adopting these technologies has been perhaps been slowed, but it is still moving forward. The key is to have a compelling business justification for the new technology.”
“We see that the global recession had an impact on RFID and printed electronics,” Mildner said. “Nevertheless, we feel that recovery is underway. This recovery can be illustrated by using the following figures: Comparing exhibitor numbers at the LOPE-C conference from 2009 to the figures of this year, the figures are already higher and still growing. They have already exceeded our expectations. LOPE-C in Frankfurt, Germany, strives to be the central meeting place of the global organic and printed electronics industry.”
Wald and Adachi noted that investment activities were impacted by the recession.
“The recession had an impact on the majority of industries, and printed electronics was no exception,” Wald noted. “Growth was somewhat lower than expected as companies had lower risk tolerance and were very careful with the funds available for investment. The rising cost of silver was also a factor, but it has come down from over $18/toz, which will also help in the adoption and growth of PE.”
“Last year, as a lingering effect of ‘Lehman Shock,‘ manufacturers engaged in a review of return on investment, and the progress of the technology’s application may have lagged from what appears to be a need for investment in consistent systems,” Adachi said.
Boone said the recession’s impact on PE was to a much lesser extent than some of the more mature markets.
“The industry continues to invest in new technology development and is also beginning to invest in pilot manufacturing for solution-processed technologies,” Boone said. “The difficult economy has not necessarily slowed this progress, but companies are doing more front-end work to prove the scalability and cost-effectiveness of these lines prior to installation.”
For Conductive Inks
There are many opportunities where PE and RFID can flourish. For example, Wald said there are several strong areas, fertile ground for conductive inks, including photovoltaics, displays, sensors, membrane switches and RFID,” Wald said.
A solar cell made with conductive ink. (Photo courtesy of Innovalight)
“While there are come creative applications being developed that fall outside of what would be generally considered as primary PE application groups, it is still too early to tell if one of these applications will have a broad market impact,” Farnsworth added.
Display technologies are a major opportunity for PE, and Dr. Philippe Schottland, director, global electronic materials technology for Sun Chemical, said that Sun Chemical is particularly well positioned in this segment.
“Point-of-purchase (PoP) displays for example is an interesting field for us,” Dr. Schottland said. “We are very well connected with printers and brand owners. As we see more and more people interested in the new generation of displays, we can help them blend graphic arts and electronic materials.”
“In the photovoltaic market, we see near-term opportunity for indoor applications utilizing printed solar cell technology, particularly energy harvesting, for low-power display applications,” Boone said. “The onset of electrophoretic displays for e-readers has spurred the manufacturing capacity that will make other applications feasible, such as POP displays, smart cards, and consumer packaging – all of which require inexpensive power sources. Our OPV ink systems have light absorption properties that fit the typical retail and consumer fluorescent use environments, making these indoor solar power applications a real opportunity for printed solar.
“OLED displays and lighting are showing near-term growth, particularly for solution-processed layers that address manufacturing cost reduction,” Boone noted. “Two particular areas of need are (1) planarization (smoothing) layers on top of the transparent electrode and (2) solution-processed transparent electrodes themselves. Plextronics' Plexcore OC inks are delivering planarization functionality while also proving to deliver improved device performance over traditional vapor deposited layers. We recently won DOE SSL funding to work on transparent conductor technology with Cambrios.”
Mildner said that there are lots of new ideas on how to use PE in the future.
“One example is electronic authentication; with electronic authentication, realized by printed electronics, you can check automatically whether a product is fake or original or if accessory parts and expendable items from the OEM are used or whether they were replaced by – in the worst case – fake products,” Mildner said. “In case of warranty, an OEM has the possibility to prove if the original accessory part or expendable item was used or a counterfeit. PolyIC observes this market intensely and sees opportunities for a further surge in this market.”
Conductive ink manufacturers are working closely with their customers to develop the products that will move the PE market forward.
“The key attributes ultimately for customers are cost and performance, but to get those answers they need to see accessibility and support,” Farnsworth said. “This is a learning process for them, and the products need to be available both in initial price and in ease-of-use. I think it is important for the providers of new technology to work hard to remove any barriers of entry for customers, which sounds obvious I know, but in actuality can be difficult to achieve. It definitely does not happen by accident.
“At NovaCentrix, this means packaging our Metalon JS silver and ICI copper-based inks in simple inkjet cartridges for use with low-cost consumer inkjet printers,” Farnsworth added. “We are also open about our pricing. At the time of this writing, a silver cartridge set costs $200, an inkjet printer $90, and a pack of PET sheets matched for use with the inks is $10. Send the prints back to us and we will run them through one of our PulseForge tools to optimize the conductivity of the inks for no charge. Or, send us the pattern file you want to print and we'll print it and cure it and send it back to you. This gets the conversation started, and helps our customers move their programs forward.”
As the leading global printing ink manufacturer as well as one of the world’s largest pigment producers, Sun Chemical has extensive experience in the ink and printing processes, as well as contacts among major brand owners and printers. The company is a subsidiary of Tokyo-based DIC Corporation, itself a leader in liquid crystals for LCD displays, as well as inks, coatings and engineering materials for electronic applications. In addition, Sun Chemical is a major player in the fields of etch resists and solder masks.
PV is an area of great interest for Sun Chemical. Dr. Schottland noted that traditional crystalline solar cells have three different metallization systems: An aluminum back surface paste, a silver tabbing paste and a front contact silver metallization paste.
“You have to be able to develop pastes that work synergistically with the wafers in a consistent manner,” Dr. Schottland said. “Quality is so important, especially when companies have metallizations lines that are producing a cell every 1.5 seconds.”
There are important trends in PV, most notably the use of thinner wafers.
“Typically, the industry standard is 200 microns, but it is going to 160 microns in Asia,” said Roy Bjorlin, director, global product manager electronic materials for Sun Chemical. “One major issue is bowing.”
“Bowing of the cells could lead to micro-cracking or breakage,” Dr. Schottland added. “As PV cells become thinner, there will also be a shorter optical path, ie. less thickness to absorb sunlight, so we are developing aluminum pastes that have demonstrated significantly lower bowing and enhanced reflectivity.”
As part of its efforts, Sun Chemical opened up a state-of-the-art 3,000 square foot cleanroom in its Carlstadt, NJ research center in mid-2009, where it is producing and testing PV solutions in a controlled environment for its customers. As a result, Sun Chemical has been able to vastly improve the conductivity of its metallization pastes and inks, and is strongly emerging into the PV market.
Boone said that Plextronics has a broad portfolio of conductive and semiconductive polymers that the company formulates into ready-to-use inks for the printed electronics market.
“We are positioned to deliver solution-processed hole injection layer (HIL) inks that not only reduce manufacturing cost due to improved yield and high-throughput processability but also provide improved device performance,” Boone noted. “Additionally, we are developing next generation HIL inks that are solvent-based and deliver unique processing capabilities and performance without the typical device lifetime concerns of water-based HIL inks. We work closely with the leading technology companies in OLED lighting and displays to deliver HIL technology that is high-performing across all emitter technologies – polymer or phosphorescent, vapor deposited or solution-processed.”
Wald noted that IIMAK has been manufacturing ink for more than a quarter of a century and has a core competency in this area. “Our R&D, sales and marketing teams are continually working with customers to provide solutions to their current and future needs,” Wald said. “Through the voice of our customers, we are able to work on new products that will drive their applications and efficiencies.
“The market is looking for ink that meets their specifications, is easy with which to work and, importantly, allows for increased processing,” Wald added. “IIMAK has, and continues to work on, ink formulations for screen, flexo and gravure methodologies that cure at 70°C (158°F) and in a short time (90 seconds to a several minutes), depending upon air flow and thickness. We are also working on silver alternative inks that allow for a cost that is both lower and less variable, as silver price fluctuates. We also provide a conductive thermal transfer ribbon, which is an excellent technology for short runs and rapid prototyping through its digital process.”
Adachi said that Toyo Ink offers a comprehensive lineup of conductive silver pastes for all conventional printing methods.
“Our RFID product offerings have proven useful not only in supply chain management systems, but also in the realization of a safe and comfortable information society, both are areas in which we see strong growth," he said. "In addition, printed electronics can contribute to the environmentally-sound production of electronic devices, a major concern in today’s society. As we can expect RFID use become more and more prevalent in the future, Toyo Ink aims to deliver products that contribute to the betterment of society in a broad, meaningful way.
“For ultra-fine circuit pattern formations, fine-point printing is naturally a must,” Adachi added. “Toyo Ink’s Rexalpha series of conductive silver paste is capable of not only ultra-high-density printing of 100 microns or less, but also has the special features required for curing at low temperatures and is formulated for a variety of applications.”
Mildner said that the new PolyIC technology for conductive structures produces transparent, conductive layers with structured and thin conductive paths made of metal with high conductivity and transparency (between 400nm - 800nm).
“These conductive structures are applied on a thin and flexible film in a roll-to-roll process and can be used for example for displays, touch sensors or electric heating elements,” Mildner said. “Currently, for these applications, ITO films or thinly integrated metal wires are used.
“Compared to ITO technology, the new PolyIC process offers various essential advantages: Individual layouts due to customer requirements in high-resolution will replace cost-consuming structuring methods that are necessary when using ITO films, high transparency in a huge wavelength range and an individual, customer-specific sheet resistance can be realized,” Mildner added. “The PolyIC films can be produced in a roll-to-roll mass production process in high volume and are cost-effective in their applications. Especially the expense factor as well as limited resources asks for new technologies that can meet the demand of a steadily growing market primarily for displays and touch sensors. With this newly developed technology, PolyIC presents an attractive alternative for transparent conductive layers.”
Expectations for the Future
All in all, conductive ink manufacturers are optimistic about the opportunities that lay ahead.
“RFID is a technology that will need time to develop and expand until it will be used on a broad basis everywhere,” Mildner concluded. “PolyIC is in continuing discussion with several customers who look for a solution in item-level-tagging, though it will take some time until this vision is implemented.”
“PE is on the cusp of becoming an explosive market and IIMAK is positioned to fuel that growth,” Wald said.
“As the industry leaders today invest in manufacturing capacity, OLED displays will lead the market growth followed by OLED lighting,” Boone noted. “TVs, cell phones and smartphones are driving OLED display growth right now, but new applications will quickly become reality as manufacturing costs decline. The organic photovoltaics market will grow as power output increases, lifetime is extended, and cost reductions are realized in parallel. Each of these markets require some key technology to drive growth: (1) low-cost barrier films/encapsulation to extend lifetime, (2) solution-processed electrodes for flexible/conformable substrates, and (3) low-cost manufacturing processes.”
“We know how to make inks,” Bjorlin said. “We are developing metallization systems with an eye toward future challenges, and we understand the complete metallization system, from particle up to application. It is an exciting field, and Sun Chemical really has its arms around it.”
“We continue to watch the space develop even as we participate,” Farnsworth concluded. “We don’t know if the next generation of flexible thin-film PV products will be released before or after the first commercial-scale true low-cost printed copper RFID antenna, or if some of the ITO-replacement technologies being developed will be implemented by the next Consumer Electronics Show. The consumers most likely won't even know if their new products use these technologies, as enabling technologies behind new products are rarely publicized. Based on the type and extent of our engagements however, the next few years could see some really exciting new products become common-place.”