Japanese researchers have developed an epoch-making new printing technology, which enables production of ultrafine silver wiring patterns only by patterning using ultraviolet irradiation and subsequent surface coating of silver nanometal ink that includes silver nanoparticles at high concentration. The technology is called "SuPR-NaP (Surface Photo-Reactive Nanometal Printing) technique" and is the result of the collaboration among the University of Tokyo, the Flexible Electronics Research Center and the National Institute of Advanced Industrial Science and Technology (AIST).

Print production - or printed electronics - technology for highly fine metal wiring that is indispensable for fine electronic circuits has faced several technological difficulties such as in reproducibility due to the contamination of printing plates or other apparatus, in sintering or fusion of metal particles on substrates after printing, in avoiding distortion of plastic substrates by high-temperature post-treatment, and in avoiding peeling off the printed wires due to the substrate bending.

The developed technique utilizes selective chemisorption phenomenon of silver nanoparticles, included in the silver nanometal ink, on an activated surface produced by ultraviolet irradiation, which is followed by the self-fusion reaction between nanoparticles to afford low-resistance silver wiring.

This technique enables easy and rapid production of ultrafine electronic circuits over a large-area substrate without using vacuum, with minimum linewidth of 0.8 um that strongly adhere to the plastic substrates.

A flexible touch-screen sensor produced by this technology is now planned to be in practical use, and is demonstrated this time by an 8-inch trial product.

Sample shipment of the flexible touch-screen sensor is planned to be begun in January 2017 by Tanaka Kikinzoku Kogyo K. K.