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Posted: Oct 04, 2012
SDK Develops Printable Conductive Silver Nanowire Inks for Electronics
(Nanowerk News) Showa Denko K.K. (SDK) has developed printable silver nanowire ink for the manufacture of electronic devices jointly with Professor Katsuaki Suganuma of Osaka University. When the ink is used in combination with Photonic Curing™ process technology, highly stable, transparent conductive patterns can be formed on flexible films.
Silver nanowire ink can produce transparent conductive films with low sheet resistance (electrical resistance measured in thin film with uniform thickness). Thus, the ink is expected to replace indium tin oxide (ITO) transparent conductive film for touch screen applications. The problem with conventional silver nanowire ink is that the application of a printing process is difficult due to ink properties and heating at high temperatures and etching are necessary after coating of the ink on a substrate. This means that it is difficult to use the ink on plastic substrates with low resistance to heat and the fabrication process is complicated. However, SDK has succeeded in developing printable silver nanowire ink by improving the ink’s properties and adhesion, enabling its use on plastic substrates. Furthermore, SDK has succeeded in instantly curing printed circuits and making them conductive by using Photonic Curing™ process technology provided by NovaCentrix, of the United States. As the conductive film based on silver nanowire ink does not require indium, a kind of rare metal used in ITO, there is no problem of natural resource restrictions.
SDK has also developed copper/silver hybrid ink. While silver ink is already used widely, it has a problem of high cost and substantial degree of migration (movement of metals on the surface of or inside a nonmetallic medium, resulting in short circuit). SDK’s new hybrid ink is made by adding a small amount of silver nanoparticles to copper nanoparticles. When this ink is used in combination with Photonic Curing™ process technology, printed patterns provide high conductivity similar to that of silver-ink-based patterns despite the high copper content. At the same time, migration is restricted to a low level. The hybrid ink can be used as a low-cost substitute for conventional silver ink and paste.
Printed electronics—the technology to manufacture electronic circuits and devices through printing, using conductive ink, etc.—is expected to be increasingly used as it enables substantial simplification of manufacturing processes. To meet future market growth, SDK will continue development of silver nanowire ink for the production of transparent conductive film. As for the copper/silver hybrid ink, SDK will start sample shipments this month.