January 20-22, 35th INTERNEPCON JAPAN/35th ELECTROTEST JAPAN/22st IC & Sensor Packaging Technology EXPO/22st ELECTRONIC COMPONENTS & MATERIALS EXPO/22st Printed Wiring Boards Expo/11th FINE PROCESS TECHNOLOGY EXPO/13th LED & Laser Diode Technology EXPO
Infrastructures for flexible device were attracted attention

January 20-22, 35th INTERNEPCON JAPAN/35th ELECTROTEST JAPAN/22st IC & Sensor Packaging Technology EXPO/22st ELECTRONIC COMPONENTS & MATERIALS EXPO/22st Printed Wiring Boards Expo/11th FINE PROCESS TECHNOLOGY EXPO/13th LED & Laser Diode Technology EXPO were held in Tokyo Big Site. In this here, main topics are picked up.

Low resistance electrode is obtained by printing Cu2O paste

First of all, Micro tech･company which is a screen printing system maker, proposed some interesting topics. One is a decorative film "Garalit" which was developed by Nakanuma Art Screen. In the booth, display system for automotive using Garalit was exhibited.

Picture 1. left：switch ON, right：switch OFF

Figure 1. Structure of automotive system using Garalit

Figure 1 shows its structure. High brightness LED was adopted as a spot illuminator, and also, Garalit was used as visible light control film with wood-surface. As picture 1 - left, in case of switch OFF, wood-surface and image of OLED are directly recognized, on the other hand, as picture 1 - right, in case of switch ON, various printed figures on Garalit are displayed by lighting of high brightness LED. By the way, stacked layers on Garalit and extraction electrode in touch panel were formed by the screen printing method.

Micro tech introduced a Cu2O paste, which was released by Nippon Chemical Industrial, too. As you image easily, Cu2O is oxidized in paste state yet, so that, it can be easily treated and housed. It's printed on the substrate, and then, is annealed at high temperature and blazing speed (2000 ℃ × a few msec) by making use of Xe flash lamp. As a result, poly crystal Cu film is obtained by fusion of Cu grains. Of course, damage against under layer is minimized because of annealing at blazing speed. For this reason, it's possible to correspond to glass, plastic film, and paper. Specific resistance is approximate 10 μΩ･cm.

Picture 2. Printed sample of CuO2 paste

Picture 3. Flexible substrate with electrode

By the way, this Cu2O paste has been used for printing of ship, due to prevention of adhere balanoid on the bottom plane. In short, cost merit is expected for printable electronics because of advantage of scale.

Patterned Al foil is used as transparent electrode of flexible device

Toyo Aluminum appealed a flexible electrode substrate with patterned Al film as alternative of the conventional ITO film. It's finely patterned on Al foil by the photo-etching method. Its sheet resistance is 0.05 - 1 Ω/□. This value is a few dozen parts of that of ITO film. The company can be supply this film at Roll to Roll state (maximum width ＝ 1100 �o). In the booth, green OLED using this Al electrode was introduced.

Curved display is gained by adoption of thinner technology of panel

Picture 4. Curved TFT-LCD monitor

Figure 2. Relationship of panel thickness and curvature radius

In spite of fabrication maker, NSC proposed an original curved display. The company is a fabrication maker by making use of wet-etching technology. In display industry, the company has operationalized thinner enterprise of TFT-LCD module and OLED module at maximum 6 G (1500 × 1850 �o) size by wet-etching using HF.

In this time, curved display was pilot-produced by use of this thinner technology. Figure 2 shows relationship of panel thickness and curvature radius. If panel thickness is 150 μm, curvature radius is 100 �o. And also, panel thickness can be reduced to 50 μm at maximum.

In the booth, curved TFT-LCD monitors were exhibited, but curved OLED was introduced in the literature, too. In short, it's possible to correspond to whole display module. By the way, business style is not fixed for the present moment.