TAIPEI, Taiwan A Taiwanese chemical lab is in the early stages of commercializing a new class of plastic material aimed at making high-quality, yet lower-cost substrates for next generation high-density DVDs.
And because of the plastic's unique properties, including thermal resistance and low dielectric constant, the lab believes it can also be used as a substrate in flat-panel displays, printed-circuit boards and as a potential replacement for silicon in fiber optic devices.
Union Chemical Laboratories (UCL), a division of the Industrial Technology Research Institute (ITRI), initially developed the metallocen-based cyclic olefin copolymer (mCOC) as a new substrate for optical discs, a huge industry in Taiwan. Its primary application would be for high-density DVDs with a storage capacity of at least 15 Gbytes.
But in working with the material, the lab discovered a few surprises. The plastic's unique ability to withstand temperatures as high as 300° Celsius and its transparency and flexibility make it an ideal candidate to replace glass as the substrate in thin-film-transistor liquid-crystal displays (TFT-LCDs), polymer light-emitting diode (PLED) displays or organic LED displays. "This high-temperature resistant (plastic) material is so unique we don't see it anywhere else in the world," said Frank Chen, acting general director of UCL.
While current CDs and DVDs use polycarbonate as a substrate, the next-generation high-density DVDs will require a substrate that doesn't absorb the shorter wavelengths of the blue light lasers needed to read the densely stored information. Today's optical disc drives use infrared or red light lasers to read CDs and DVDs.
The lab is working with Ritek Corp. and CMC Magnetics, Taiwan's top two CD-R makers, to explore the feasibility of adapting the mCOC material to their current polycarbonate-based manufacturing process. At the same time, UCL is also showing upstream plastics manufacturers how to set up a production system for making the material. By working concurrently along different parts of the supply chain, the lab hopes the material will reach commercial volume in the optical disc industry in about two years.
Several companies are eager to work with the lab on licensing the material, even though development of a large-scale manufacturing process is still in the pilot stage. The early interest is based on Taiwan's top position as a CD-R maker. Last year, the island supplied about 80 percent of the 5.5 billion CD-Rs sold worldwide, according to ITRI.
This makes Taiwan a huge consumer of polycarbonate plastic material. So companies like Formosa Plastics and Chi Mei are reportedly exploring the feasibility of setting up large-scale production facilities that would supply Taiwan's CD-R makers and the growing number of FPD suppliers researching next-generation substrates.
The lab is also keen to accelerate the promotion of the plastic as a flexible substrate in cell phones and PDAs. Companies like Ritek Display Technology have tested the material as a substrate, but it's too early to tell if it will carry easily into mass production. "The preliminary results look OK," said Chang Yih, general manager at RTC. "But its development depends on the price."
Based on estimates of a U.S. consulting company, Chen said mCOC is about 30 percent cheaper than polycarbonate (PC) when produced in volume. "The main reasons are that the raw material costs are low and the process is simple," Chen said. It's also less dense and absorbs 20 times less water than PC, making it usable for precision lenses, and it is 10 times stronger than glass at half the thickness.
Chen foresees mCOC enabling cheaper next-generation displays as thin as paper that "you could just roll up." The plastic relieves a key bottleneck in the drive toward flexible flat-panel displays, he said. Other companies are also at work on similar applications, such as Universal Display Corp., and numerous futuristic applications have been dreamt up.
"The potential we see is that next-generation mobile phone users will want to go on the Internet, but the screen is not really big enough. But you want it to be portable. So how do you compromise these two extremes?" Chen said. "One possibility is that you make the screen foldable. When you want to go on the Internet, open up the big screen. When you're done, fold it up so you can carry it. That's impossible with glass."
According to Chang, Sharp is currently the only company that commercially uses plastic as a substrate for its STN-LCDs used in cell phones. Chen also noted that Japanese as well as German companies have developed a variation of the polymer material. But the Japanese version, COC, is twice as expensive, and the German version of mCOC cannot withstand temperatures above 200° C, because it was developed for medical and packaging purposes, Chen said. He asserted that UCL's version fills a niche because it is cheaper than regular COC, making it attractive in the low-cost optical disc market, and because it is tough enough to withstand the high-temperature manufacturing process for color TFT-LCDs.
The lab has four teams working on different grades of the plastic for separate applications: optical discs; TFT-LCDs, printed-circuit boards and optical components, such as polymeric wave guides, which would be cheaper than today's silicon-based versions.
The catalyst used by the lab was crucial to the technology breakthrough. By making key adjustments to the metallocene chemical structure, the lab created a high-temperature-resistant material. Although there are several applications for the plastic, ranging from medical and food packaging to electronics, the lab will focus on its use in optical applications.
The other working groups will continue to explore the plastic's suitability as a base material for pc-boards, based on its high temperature resistance, low dielectric constant and low dissipation value. The potential value of the plastic in optical communications and light-wave transmitting devices will also be aggressively explored.
UCL, in conjunction with other labs at ITRI, is developing a polymer-based light-wave guide as an alternative to silicon-based technology, which Chen said is "very good and very stable, but also very expensive."
Because the high cost of optical components is a hurdle to bringing wideband Internet to the home, Chen said, "People are looking for a much cheaper way to do it, and the cheapest way is to use plastic. We have proven the feasibility. And we foresee that it has huge commercial potential down the road, because with all optical components, the consumers are not going to be able to afford thousands or even hundreds of dollars."