FINETECH JAPAN 2021/12th FILMTECH JAPAN/10th PLASTIC JAPAN
Printing undertaking enterprise and transparent polyimide film were easy to notice

December 8-10, FINETECH JAPAN 2021/12th FILMTECH JAPAN/10th PLASTIC JAPAN were held in Makuhari Messe. Main topics in these exhibitions are picked up.

High heat-resistant PI film is adopted as a substrate of Innolux's Mini LED

Picture.2 Mini LED display using Xenomax substrate

Picture.1 Comparison of heat resistance 　The conventional PI film (above), Xenomax (under)

Xenomax Japan, a joint venture of Toyobo and Nagase, introduced an original polyimide (PI) film with low thermal expansion (Xenomax) in Toyobo's booth. Its heat resistance is greatly high same as 500 ℃. As picture 1, heat resistance of Xenomax is higher than that of the general PI film. Furthermore, linear coefficient of expansion is low same as 8 ppm/℃, which is almost same value of glass. In short, high robust such as that of silicon wafer and ceramics is ensured. And also, surface flatness is mere Ra ＝ 0.5nm.

In the booth, E-paper of E-Ink and 5-inch mini-LED display of Innolux Display were exhibited. The former has been adopted in mass production yet. The latter is greatly thin same as approximate 2 �o. Of course, LED display is obtained by use of single substrate. Its resolution is relatively low same as 960 × 540 pixels, however, it's sufficient for industry display. By the way, this mini LED display will be released in near future.

Nakamoto Packs launches rotary screen printing undertaking

Picture.3 Rotary printing sample

As above, proposals of printing undertaking enterprise were easy to notice. First of all, Nakamoto Packs announced to launch undertaking enterprise of the rotary screen printing. In this enterprise, it's possible to correspond to large substrate, maximum 508 �o width and print at seamless patterning because of its printing mechanism. Printing resolution is L&S＝100μm/200μm order. Not only line shape such as electrode, but also dot shape can be printed. In the booth, Ag paste printed sample on PET film was exhibited. The company is supplying printed samples for FPC for the present moment.

Seiren appealed IJ printing undertaking

Picture.5 IJ printing sample on concave substrate

Picture.4 IJ printing sample on cloth

On the other hand, Seiren announced to embark ink jet (IJ) printing undertaking. In this enterprise, various functional inks are printed on various substrates by making use of an originally developed IJ system. It's possible to correspond to large substrate same as 2000 �o width, and relatively fine resolution same as 60 μm width. Of course, it's easy to correspond to difficult works for the other printing methods because of non-contact printing. In fact, picture 4 and 5, many samples such as cloth, dot prism, curved and concave substrates were exhibited.

New transparent PI materials were introduced for flexible device

As regards transparent PI materials, Nippon Steel Chemical and Material exhibited a transparent polyimide CCL (Copper Clad Laminate) for transparent FPCs. It's copper-clad laminated wiring board, which is composed of transparent PI film and Cu foil. Of course, after patterning of Cu film as circuit, a transparent CCL is obtained. Its transmittance and thermal expansion of coefficient were 87 % and 18 ppm/℃ respectively. Flexibility and heat resistance are superior to them of PET film and COP film.

By contrast, Mitsui Chemical exhibited a transparent polyimide varnish "ECRIOS". It's a substrate for flexible device. Transparent PI substrate is obtained by coating on the support glass and hardening. Its transmittance and thermal expansion of coefficient are 88 - 90% and 10 - 55ppm/℃ respectively. Of course, if this substrate is bended, basic characteristics don't almost degraded.

Shin-Etsu Polymer exhibited a transparent conductive polymer

Picture.6 Comparison of charge 　without coating (left), with coating (right)

As concerns other transparent material, Shin-Etsu Polymer appealed a new PEDO/PSS polymer. It's useful for transparent electrode, prevention of static charge, and so on. Sheet resistance can be controlled from 100Ω/□ to 10¹¹Ω/□ at will. As picture 6, demonstration of prevention of static charge was done in the booth. It's verified that styrofoam balls were simply charged by coating this material.