Pancake recipe serves up flexible displays

Researchers at Taiwan's Industrial Technology Research Institute (ITRI)   working on a flexible display technology were stuck - literally - until one engineer recalled a family pancake recipe that solved the problem, paving the way for a new generation of displays. Here's what happened, as relayed by ITRI vice president John Chen.

ITRI engineers had created a flexible plastic material that they hoped would replace the glass backplane that's used as the foundation in most displays we use today, from smart phones to laptops to e-book readers. The new material, dubbed FlexUPD, would enable manufacturers to build display panels on a foundation that was far lighter, thinner (1/10th the thickness of a glass panel) and more durable -- and that might eventually be used in devices where a display could be curved, flexible, bendable -- or even rollable.

The big obstacle to using a plastic substrate is heat: An active matrix of thin, film transistors underlies most display media. It's used to drive display media ranging from liquid crystals to OLEDs to e-paper. In the factory, the silicon-based transistors are applied to the glass backplane at temperatures that would melt plastic.

ITRI had developed a temperature-resistant plastic that was strong enough to withstand the embedding of an active matrix. The manufacturing process called for the plastic membrane to be mounted on a glass backing panel for two reasons: The flexible material needed a rigid surface behind it while the active matrix was being applied so that it didn't deform, and fabrication plants designed to build traditional displays on glass substrates would be able to use the same manufacturing process to produce flexible displays with minimal modifications. "You wouldn't have to go out and spend another billion dollars to build another fab to make this," says ITRI vice president Dr. John Chen.

There was just one problem.

The process applied the active matrix to the plastic perfectly, but the resulting heat bonded the plastic to the glass panel behind it. "Every time we peeled it, we tore it or it wouldn't work," Chen says. ITRI engineers tried all sorts of ideas to try and solve the problem -- and failed -- 63 successive times.

Then one engineer had an idea. Inspired by a traditional Chinese recipe for making pancakes, he suggested that the team develop a layer of "cooking oil" that could be applied to the glass and that would remain sticky until heated by the active matrix application process. Once the coating had been "fried" by the application of the active matrix, it would release the "pancake," or plastic display backplane, from the "hot pan," or glass panel.

That lead to the development of a polyolefin separator, an oil-like material that did the trick. Attempt 64 was the charm.

Sometimes, says Chen, "a technology breakthrough can be inspired by a small wisdom in daily life, such as pancake making."

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