Fujitsu Develops World's First Touch Panel Using Conductive Polymer Film

Fujitsu Laboratories Ltd. and Fujitsu Component Limited today announced the joint development of the world's first resistive touch panel⁽¹⁾ that uses a conductive polymer film⁽²⁾, a transparent conductive film that offers durability 10 times that of the conventional ITO⁽³⁾ film and succeeds in reducing production costs to less than half. Volume production capabilities for this breakthrough technology have been confirmed.

The new technology is applicable not only to mobile devices such as mobile phones, PDAs and tablet PCs, but enables applications for which use of touch panels was not conventionally possible from a cost perspective, opening up new markets in the move toward a ubiquitous information era.

Background
With the proliferation of mobile devices such as mobile phones, PDAs and tablet PCs, there is increasing demand for touch panels that offer direct input of information to these devices. Touch panels enable more immediate and direct interfacing, without the use of a keyboard or mouse.

Technological Issues
Currently, PDAs and tablet PCs primarily use resistive touch panels with transparent electrode film, for which ITO film is used. However, as ITO film is formed by layering a brittle, ceramic thin film over the flexible plastic film, repetitive input movements caused minute cracking, resulting in the degradation of the film's characteristics. ITO film layering also requires costly vacuum process equipment, which made cost reduction difficult.

Fujitsu's New Technology
The new technology incorporates the use of conductive polymer, an organic material that is just as pliable as plastic film, as the transparent electrode film for touch panels. By evenly layering with nanometer precision, a low resistance conductive polymer, as a transparent electrode film on to a plastic film, Fujitsu has succeeded in developing the world's first application of a conductive polymer for touch panels.

Features of the new technology are as follows:

1. Conductive polymer material technology:
   High conductivity and transparency By applying rod-like molecules that strongly interact with conductive polymer molecules in order to control the conductive polymer alignment, electron conduction paths (routes through which electrons pass) were evenly laid, enabling the lowering of resistance to one-half that of current levels. Utilizing this method, Fujitsu has achieved high conductivity and transparency equivalent to those of conventional ITO film.
   
2. Conductive polymer formation technology:
   High levels of surface-resistance uniformity Fujitsu developed a coating technology that uses eco-friendly water-based solvent to uniformly and quickly coat the conductive polymer on to plastic film surfaces, such as polyethylene terephthalate (PET), used as a base material for touch panels. This enables film thickness uniformity within 10 nanometers. Utilizing this technology, Fujitsu succeeded in achieving a high level of surface resistance uniformity that is required for touch panels.

Significance of this Technology

In durability testing on touch panels developed with this technology, no structural degradations or resistance increase occurred even in pen-input tests with over 200,000 repetitions. This is attributable to the flexibility of the conductive polymer thin-film on the plastic film, which features durability over 10 times that of conventional ITO film performance, and can be considered to last a lifetime under practical use.

With the newly developed conductive polymer formation method, utilizing a roll coater⁽⁴⁾ makes it possible to coat a large area all at once, resulting in superior productivity that reduces production cost of transparent electrode film to less than one-half in comparison to ITO film. High applicability of the new technology for volume production has also been tested and confirmed through practical application testing using actual production processes.

Future Developments

Fujitsu Components will establish volume production technology for the new touch panels with the aim of early commercialization. Development of technologies for higher transparency and lower panel production costs will continue along with development for new applications of touch panels in the coming age of ubiquitous information.