DNP Produces Transparent Conductive Film by Printing Method, Looks to Replace ITO

Apr 28, 2009 19:56 Megumi Yoshizawa, Nikkei Microdevices

Dai Nippon Printing Co Ltd (DNP) developed a transparent conductive film that is designed to replace indium tin oxide (ITO) films.

In place of expensive indium (In), DNP used silver (Ag), etc for the conductive particles. Not only can the film be formed with patterns in desired areas by a printing method, which is suitable for mass-production, it is also flexible.

It intends to replace ITO films used in touch panels, OLED panels and electronic paper. The company will start shipping samples in May 2009 and sell the film on a full-scale basis from fall 2009.

This time, DNP improved the printing method and the materials so that the patterns can be uniformly formed only on the required area of the film substrate. This eliminates a number of production steps such as vapor deposition and etching, while enabling continuous roll-to-roll processing with the use of an approximately 1,000mm-wide film, according to the company.

On the other hand, to form a pattern in the desired area on an ITO film, a number of steps such as light exposure, development, etching and cleansing are required after a conductive material is deposited on a film.

When a pattern is formed on a flexible film by a printing method, it is possible to prevent cracks and scratches, which may occur when the film is being bent, by forming conductive particles in a fine mesh pattern, DNP said. By carefully selecting process materials and improving working process, the company achieved a resistance of 0.1Ω/cm² with the new film.

Also, the newly developed film functions as a lightweight, thin and flexible transparent wave absorber. Because its mesh portion was designed with a pitch of several dozen microns to several millimeters, the film can block radio waves in a given frequency.

For example, the film can be used to block mobile phone signals when it is attached to glass walls, windows, doors, etc in hospitals, according to DNP. In contrast, when ferrite is used as a wave absorber, it needs to be embedded in a glass plate.

For applications such as transparent conductive films and wave absorbers, DNP is aiming at sales of ¥3 billion by 2012. Fujifilm Corp and Gunze Ltd also announced similar conductive films designed as a substitute for ITO films (See related article 1, 2).

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