TDK Develops Thinner Transparent Conductive Film for Touch Panels

Oct 3, 2013
Naoki Tanaka, Nikkei Electronics
Two 15-micron-thick films attached together (lower). It is sagging because of its slimness. Two 125-micron-thick films attached together (upper).
Two 15-micron-thick films attached together (lower). It is sagging because of its slimness. Two 125-micron-thick films attached together (upper).
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TDK Corp developed a 15μm-thick transparent conductive film targeted at the capacitive touch panels of tablet computers and smartphones.

To reduce the thicknesses of tablet computers and smartphones, there is an increasing demand for thinner touch panels, which are one of their main components. According to TDK, the thickness of the transparent conductive films that are currently used for capacitive touch panels is 125μm. But a growing number of 50mu;m-thick products have been shipped in 2013, and they are expected to become mainstream in 2014, the company said.

Moreover, TDK considers that even thinner products will be required in 2015. Therefore, it developed the 15μm-thick transparent conductive film ahead of other companies. The company aims to release the film in 2015.

The reason why it is difficult to reduce the thickness of transparent conductive film is that the film tends to deform in the manufacturing process because of the influence of heat, etc, affecting the process of forming a transparent conductive layer on the film. As a result, the thickness of the layer becomes uneven, making it difficult to realize uniform properties.

This time, TDK solved such problems by using its knowledge and know-how accumulated through the development of magnetic tapes for about 30 years to optimize the selection of the base material of the film and a transparent conductive material as well as the conditions of the film formation.

Also, TDK handles all the processes from the development and selection of materials to the production of transparent conductive films at its Mikumagawa Plant in Hita City, Oita Prefecture, Japan. Without such an integrated manufacturing system, the latest development would have been difficult, the company said.

As a transparent conductive material of the latest transparent conductive film, TDK used an ITO (indium tin oxide) film formed by using a sputtering method. Its sheet resistance is 100Ω/□, which is suited for capacitive touch panels.