News Release

July 21, 2011
Hitachi Chemical Co., Ltd.

Developed Transfer-type Transparent Conductive Film Enabling Patterning to Various Substrates
— New film reduces processes and contributes to boost productivity —

Hitachi Chemical Co., Ltd. (Head Office: Tokyo; President and CEO: Kazuyuki Tanaka; Capital: 15.5 billion yen; hereinafter referred to as "Hitachi Chemical") has developed a transfer-type transparent conductive film for touch panels that can be transferred and attached to various substrates. In addition to flexibility and photolithographic fine patterning capability, it realizes compatibility between conductivity and transparency such as surface resistance of 10 to 250 Ω/sq (Note 1) and light transmittance of 85 to 91% (Note 1). Hitachi Chemical plans to establish production capacity of several hundred thousand ㎡/month by September 2012, proactively expanding its usage to wider areas such as organic ELs, electronic papers and solar cells to achieve annual sales of six billion yen in fiscal year 2015.

In recent years, against the background of an expanding market for smart phones and tablet PCs, there has been a rapidly increasing demand for transparent conductive films used in touch panels, which are a key component of these products. As for transparent conductive film, indium tin oxide (hereinafter referred to as “ITO”) film deposited on a glass substrate is generally used today for touch panels. The glass substrate is known to have issues on fragility and weight, and substrates like polycarbonate (hereinafter referred to as “PC”) or polyethylene terephthalate (hereinafter referred to as “PET”) films that are light in weight and flexible have been proposed as the alternatives. ITO, however, is relatively inflexible and increases electric wiring resistance with screen size. In addition, vacuum processes such as vaporization or sputtering are required for ITO film deposition and this makes it difficult to reduce the equipment investment and cost of production. All these problems called for the development of a new conductive material that matches various flexible substrate materials and contributes to productivity improvement.

Hitachi Chemical started joint development work with a U.S. venture company Cambrios Technologies Corp. (Head Office: California, the U.S.; President and CEO: Michael R. Knapp) in 2005 and has merged their silver nanowire conductive ink “Clearohm™”(Note 2)” with our evolved photosensitive dry films for printed wiring boards technology to realize a transfer-type transparent conductive film. The film has high flexibility, and can be transferred and attached to various substrates like PC films and PET films as well as to glass, and to materials having a three-dimensional shape. In addition, its surface resistance is adjustable (10 to 250 Ω/sq) according to the requirements of the final products. It realizes a level of compatibility between conductivity and transparency that equals that of ITO. As this product is supplied in roll form, it is compatible with the roll-to-roll (Note 3) process, and it can be transferred and attached to substrates without the vacuum process needed for ITO deposition. It enables fine patterning by exposure and alkaline development. These features help customers to reduce the number of processes and also improve productivity.

Sample shipment of the product is underway to domestic and international customers for touch panels used in smart phones and tablet PCs. We plan to establish a production capacity of several hundred thousand ㎡/month by September 2012. In addition to focusing on increasing sales in the expanding touch-panel-related materials market in conjunction with the optical clear adhesive (hereinafter referred to as “OCA”), FINESET, which improves visibility, we plan to expand its application to new areas such as organic ELs, electronic papers and solar cells by utilizing its unique features.

Note 1. Surface resistance 10 to 250 Ω/sq and light transmittance 85 to 91 % are the values when this product is transferred/attached and patterned onto a PC film one mm thick.
Note 2. Clearohm ™ is a trademark of Cambrios Technologies Corporation. Clearohm is a silver nanowire conductive ink capable of forming a natural-colored transparent conductive layer that is superior to ITO and other transparent conductive oxide films.
Note 3. The roll-to-roll process is a method mainly used to produce electronic components efficiently. For example, if a roll-form substrate with a printed circuit pattern is attached to a roll-form sealing film, etc., and then is rolled up in the last stage, then all the substrates are connected and equipment/tasks required for transportation can be eliminated, thereby contributing to productivity improvement.

= Reference =

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An Example of Cross Section of a Touch Screen Using
Transfer-type Transparent Conductive Films