Reel to reel technology, such as is used in the newspaper industry, is considered to be faster than traditional methods of handling substrate material. Institutes like Fraunhofer IZM are preparing smart cards/labels using continuous production lines.
Central to the success of this manufacturing route is the use of polymer based thick-film pastes that can be screen-printed using specially adapted printers that accept a reel to reel process.
ESL ElectroScience and ESL Europe manufacture screen-printable, polymer silver pastes which can be used in large volume manufacturing routes such as the reel to reel process.
ESL 1901-S is a silver-filled, flexible resin material designed for use as a conductor on low-temperature substrates.
This silver conductor can also be used in the manufacture of four and five wire analogue resistive touch panels, for printed antennas in RFID applications and as conductors in flexible solar cells. After screen-printing and curing the silver film remains reasonably flexible and the resistance of the conductor remains constant over time. This versatile polymer has also been successfully used on other substrates such as cloth.
Ridged glass is coated with a thin layer of semiconductor, indium tin oxide. Conductor lines are printed onto two sides (say north and south). A spacer is added between this glass and the flexible layer, which is also coated with indium tin oxide, and it is this flexible layer which the user sees. This also has bars with polymer conductive paste down the opposite sides (east and west) and the flexible layer is inverted to make connection in places with the coated glass. This touch screen is interfaced with an LCD display with the aid of controllers and multiplexers as necessary. 1901-S variants are included on the ESL website www.electroscience.com .
John Whitmarsh, Technical Service Manager at ESL - Europe told Printed Electronics World "ESL acknowledges the plastic electronics revolution on flexible substrates is here to stay and we will meet our customers' challenges with off-the-shelf products, and with the development of proprietary or custom formulations."
ESL delivers low-cost, high-reliability, stable and reproducible materials in an ISO 9001:2000 environment, scaling up from laboratory and pilot-scale quantities to high-volume production. ESL ships orders of thick-film materials that range from a few grams of paste and sheets of tape to tonnage or millions of square metre lots. They have manufacturing sites in Pennsylvania, USA and Reading, UK.
ESL is developing flexible polymer based resistors for embedded circuitry.
For more attend Printed Electronics USA 2008.
Photo and diagram courtesy of A Touch, Korea.