Starkey, P. (2011), "Printed Electronics – Technologies and Applications, Electronics Yorkshire, 23 September 2010", Microelectronics International, Vol. 28 No. 1. https://doi.org/10.1108/mi.2011.21828aac.001Download as .RIS
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Printed Electronics – Technologies and Applications, Electronics Yorkshire, 23 September 2010
Article Type: Conferences and exhibitions From: Microelectronics International, Volume 28, Issue 1
The Electronics Yorkshire Centre is located near the city of Leeds, in the historic county of Yorkshire in Northern England. Electronics Yorkshire is a not-for-profit organisation whose aim is to support and assist the growth of the electronics sector with technical support, networking and electronics training. Print Yorkshire is a recognised voice of print both nationally and internationally, and aims to promote the print and print packaging industry in Yorkshire, and to create business opportunities for buyers and sellers of print.
Electronics Yorkshire and Print Yorkshire co-operated in organising a networking seminar with the theme Printed Electronics – Technologies and Applications, which brought together a diverse group representing the electronics industry, the print industry, academic institutions and technology developers, to share information on recent developments in printed electronics.
Dave Williams, Electronics Yorkshire Business Development Manager, opened the seminar and introduced the first speaker, Professor Martin Goosey from the Innovative Electronics Manufacturing Centre at the University of Loughborough, whose presentation was entitled Printed Electronics and the IeMRC. Professor Goosey explained that “printed electronics” and “plastic electronics” were general terms used to describe electronics based on semiconducting organic polymeric materials, which are deposited using additive or printing techniques, with many applications offering a competitive or superior mix of novel performance and manufacturing economics. Printing technologies offered lightweight and robust electronics at low cost on large area flexible substrates, and were being developed by by over 3,000 companies, universities and research institutes worldwide. The market for printed electronics was just beginning to emerge, and in 2010 the market for printed and thin film electronics was expected to reach $1.92bn. Immediate applications were in RFIDs and OLED displays manufactured using organic thin film transistor technology.
IeMRC were currently supporting three printed electronics projects: Brunel University were using lithographic techniques to produce printed battery structures based on zinc – manganese dioxide chemistry, with silver current collectors, which were being commercialised by manufacturers of “amplified experience” greetings cards. Brunel was also currently collaborating on applications with a pharmaceutical company. University of Surrey were studying the effects of deposition technique on the electrical and morphological characteristics of poly(3,4-ethylenedioxythiophene), PEDOT, an organic alternative to indium tin oxide. Inkjetting gave better control and less material wastage than spin coating, but required careful attention to coating and drying conditions in order to achieve comparable electrical properties. The universities of Oxford, Leeds, Manchester and Bangor were collaborating in a new IeMRC flagship project on roll-to-roll vacuum-processed carbon-based electronics, adapting vacuum-coating techniques already well-established in the food-packaging industry as the basis of a manufacturing technology for high-volume, low-cost electronic devices for anti-counterfeiting, brand protection and product tracking applications. It had already been demonstrated that simple transistors could be fabricated in high yield and at high speed through this roll-to-roll process, and the main technology hurdles to be overcome were the optimisation of process conditions for the deposition of organic and inorganic thin-film multilayer structures.
Professor Goosey commented on the growing importance of nanotechnology as a key enabler in printed electronics and the wide range of potential applications that had been identified for carbon nanotubes, which had good mechanical, thermal and electrical properties making them ideal for use in conductive composites and inks, and copper nanowires, which could be coated from solution in a roll-to-roll process to form a transparent conducting layer as a potential replacement for indium tin oxide, particularly in flexible displays and thin solar panel applications.
Professor Long Lin, Director of the Digital Print Centre for Industrial Collaboration at the University of Leeds, focused his presentation on mass production applications of printed electronics that the printing industry could easily engage with using existing conventional printing technology. He took medical diagnostic sensors as his first example of products well-established in manufacture, and described the principal characteristics of a blood glucose sensor. Although the device was a relatively complex multi-layered structure, with a PVC substrate, carbon conductors, silver-silver chloride reference electrode, polymer membrane and dielectric layers, it was produced in high volume at low cost by a process sequence involving rotary screen printing, aerosol printing, lamination and flexographic printing, with on-line quality control. Other examples included sensors for blood cholesterol and blood alcohol and for monitoring the freshness of food. There were exciting opportunities for interactive packaging in retail and health-care sectors, one example being intelligent packaging for pharmaceuticals to improve patient compliance. Electronics were beginning to be incorporated into textiles for medical, military, industrial, commercial and residential applications. The principal challenge was to produce conductive tracks and interconnections with realistic wash-, wear- and crease-resistance.
Dr Steve Jones of Printed Electronics Ltd reviewed the state of the art of printed electronics in a presentation entitled Digital Printing of Electronics – Putting Electronics in New Places. The principal difference between traditional electronics and printed electronics was that the former could call upon millions of man-years of data on component function and reliability, whereas there was no library of component data for printed electronics and little information on function or reliability. The “components” were inks, typically in the form of nanoparticles in a carrier that gave an appropriate surface tension and viscosity for the printing method, which could be screen printing, flexography, gravure, offset lithography or inkjet. And the inks could form conductors, dielectrics, active or passive devices. Dr Jones’ main area of interest was inkjet printing, a fully additive non-contact digital process requiring no tooling, which was an extremely versatile means of placing functional inks on unusual surfaces and awkward contours, including the ability to print down into recesses. Electronically functional materials could be combined with colour graphics to produce, for example, active graphics for smart packaging applications. He discussed print-heads, printing machine platforms and ink-substrate interactions, in particular the functionalisation of ink after printing – a typical silver nanoparticle ink contained 50 per cent by weight of metal. What happened to the other 50 per cent, and how could high conductivity be achieved? A characteristic of the better-quality silver nanoparticle ink deposits was their remarkably low sintering temperature, and high conductivity could be achieved on low cost paper or plastic substrates by oven baking at 120°C or xenon-flash curing. Dr Jones ended his presentation with some illustrations of process economics and cost calculations for single-layer nano-silver circuits.
Final presentation came from Bela Green, Patterning Programme Manager at Printable Electronics Technology Centre (PETEC), the PETEC, a design, development and prototyping facility based in the north east of England. PETEC provided help to bring new printable electronics products to market quickly by offering facilities and expertise not generally available in-house, reducing the client’s level and risk of capital investment. Their Sedgefield site had a large clean-room area supported by laboratories for formulation and electrical testing. Initially, work was concentrated on the development of printed transistor backplanes for flexible displays, although the equipment would also enable the fabrication of proof-of-concept solid-state lighting and organic photovoltaic products. A reel-to-reel vacuum sputter coater and facilities for testing the barrier properties of plastic substrates were housed in their flexible electronics substrate facility, where they were also working on tailored substrates for the manufacture of flexible photovoltaic cells, thin film transistor displays and solid-state energy-efficient lighting. A third facility specialised in new applications of Atomic Layer Deposition films. Ms Green introduced the concept of Integrated Smart Systems, a hybrid approach using conventional and printed electronics to produce items by the integration of electronic components with circuits prepared by traditional print processes in order to realise close-to-market printed electronics applications by building upon technology already existing within printing, electronics and packaging organisations, and providing the facility to trial processes at PETEC rather than stop existing production lines.
This seminar very successfully achieved its objective of getting electronics people and printing people to understand some of the concepts of printed electronics and what potential technology and business opportunities might await those prepared to apply some lateral thinking and look a little way beyond the boundaries of their traditional technology areas. It opened some eyes, satisfied some curiosities and provoked some constructive discussion, out of which will surely come some productive collaboration. Electronics Yorkshire and their associates at Print Yorkshire are to be commended for their initiative. www.electronicsyorkshire.org.uk, www.printyorkshire.com
Pete StarkeyEAB Member – Circuit World