Panasonic Corp succeeded in prototyping a "micro wiring electrode film" that uses a copper (Cu) mesh pattern and can be used for a 70-inch capacitive touch panel.
The company will provide the film to device and touch panel makers so that they can test it in digital signage devices, electronic blackboards, etc.
To make the micro wiring film using the Cu mesh pattern, a material made by attaching a PET film to a Cu foil is processed by exposure, development, etching and detachment. The surface resistance of the new film is 0.5Ω/□, which is about 1/100-1/300 those of existing ITO films, preventing signal degradation and making it easy to realize a large-size touch panel.
Since Panasonic announced the development of the film June 4, 2013, about 20 Japanese and non-Japanese firms showed interest in it, the company said. Because many of those firms were interested in using the film for 70-inch touch panels such as of electronic blackboards, the company started to prototype the large-size film.
Before the latest film was announced, the largest size of the film that Panasonic showed at, for example, trade shows was for 47-inch touch panels. The manufacturing equipment for the film supports about 80-inch size. And the company is planning to prototype a film for 80-inch touch panels in the fall of 2013.
Unlike transparent electrodes such as ITO electrodes, the wiring of the Cu-based electrode film is visible. To solve this problem, Panasonic employed black wiring and reduced the thickness of the wring to 2μm and the width to up to 5μm so that it becomes difficult to see the wiring (The width of the 70-inch model's wiring is 8μm).
Moreover, if moire is generated when the lattice of pixels laps over the lattice of Cu wiring, Panasonic will fine-tune the interval and angle of the wring in accordance with the shape of each manufacturer's pixel.