Japanese invest heavily in plastic substrates for LCDs

28 Jun 2002

Sony has reportedly developed a plastic, full-colour LCD that is one-seventh the weight and less than one-third the thickness of conventional glass-substrate alternatives.

According to the Nikkei Business Daily, Sony hopes to commercialize the technology in a few years' time to cut the weight of mobile phones and personal digital assistants.

The LCD is a thin-film transistor type and Sony has already produced a 1.5 inch diagonal prototype with a thickness of 0.4 mm compared with 1.4 mm for conventional glass-based LCDs. The device weighs 0.5 g.

A 3.8 inch plastic LCD for mobile phones would weigh just 3 g, compared with 20 g for its glass alternative, Sony sources say.

Until now there have been manufacturing difficulties using plastics in thin-film LCDs because temperatures of almost 400°C are needed to make a polysilicon circuit. Sony's method makes the circuit on a glass substrate and then transfers it to a plastic one.

In a related move, 10 Japanese companies, not including Sony, have formed an R&D consortium to develop plastic substrates for mobile devices. The companies intend to spend ¥  1.5 bn (€  12.7 mn) over the next five years to develop a suitable material and manufacturing technologies.

Members of the consortium include Sumitomo Bakelite, Dainippon Ink and Chemicals, Konica, JSR, Sumitomo Chemical, Dai Nippon Printing, Toray Industries, Toppan printing, NEC and Hitachi Chemical.