Smartphone Screens Will be Made out of Sapphire

Manufactured sapphire—a material that’s used as transparent armor on military vehicles—could become cheap enough to replace the glass display covers on mobile phones. That could mean smartphone screens that don’t crack when you drop them and can’t be scratched with keys, or even by a concrete sidewalk.

Sapphire, a crystalline form of aluminum oxide, probably won’t ever be as cheap as Gorilla Glass, the durable material from Corning that’s used to make screens on iPhones and other smartphones. A Gorilla Glass display costs less than $3, while a sapphire display would cost about $30. But that could fall below $20 in a couple of years thanks to increased competition and improving technology, says Eric Virey, an analyst for the market research firm Yole Développement. And since sapphire performs better than glass, that price could make it cheap enough to compete.

By some measures, Sapphire is three times stronger than Gorilla Glass, and it is also about three times more scratch resistant. That’s why Apple uses it now to protect the camera on its iPhone 5. Virey says that all major mobile-phone makers are considering using sapphire to replace glass. Some high-end smartphones should be using sapphire in 2013.

Crystal clear: These unpolished, uncut boules of manufactured-sapphire crystal weigh 130 kilograms (left) and 100 kilograms (right).

An alternative to using pure sapphire is to laminate an ultrathin layer of sapphire with another, cheaper transparent material, maintaining much of the performance advantage of sapphire at a cost comparable to that of the glass typical in mobile-phone displays.

For this purpose, GT Advanced Technologies, based in Nashua, New Hampshire, is developing a method for making sapphire sheets thinner than a human hair—much thinner than the nearly millimeter-thick glass used now on mobile phones.

To make the sapphire, aluminum oxide is melted down in a specialized furnace and then allowed to slowly cool to form a large crystal. That crystal is then cut with a diamond-coated wire saw. GT designs its furnaces so that they can be cheaply upgraded to make ever larger crystals as the technology improves, allowing customers to increase production without buying new equipment.

GT is more optimistic about prices than Virey, estimating that sapphire displays might cost only three to four times as much as those made from Gorilla Glass. People at the company say prices will fall further as GT improves its furnaces, and as the manufacturers that buy those furnaces streamline their operations.

SOURCE – Technology Review

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