How Corning won Apple back and built the strongest Gorilla Glass yet


Corning's Gorilla Glass. Photo: Corning
Gorilla Glass is the go-to material for today's touchscreens. Photo: Corning

Corning’s relationship with Apple looked doomed earlier this year. Having manufactured the touchscreens for every iPhone since 2007, the Gorilla Glass bosses were all but sure they were being ditched in favor of synthetic sapphire crystal, set to be supplied by Apple’s hot new partner, GT Advanced Technologies.

But while Apple’s affair with GT has imploded spectacularly, Corning is back on Cupertino’s crush list after stepping in at the eleventh hour to create super-sized displays for the iPhone 6 and 6 Plus. Now Corning is convinced its latest technological advance — Gorilla Glass 4, its toughest version yet — will banish sapphire suitors for the immediate future.

“Sapphire is a really, really nice material that’s very good for reducing scratches,” Dave Velasquez, Corning’s director of marketing and commercial ops, told Cult of Mac. “However, we feel very strongly that glass is the best material for touch panel cover glass. When you weigh up everything from cost to drop-testing, to the amount of energy that’s needed to make it, in our opinion Gorilla Glass is clearly the best material to use.”

Sapphire might have captured all the buzz in the run-up to the iPhone 6 and Apple Watch, but Gorilla Glass is still the substance most of us tap and swipe on a daily basis.

In addition to Apple, Gorilla Glass covers the front of practically every high-end smartphone and tablet on the planet. Named for its toughness and durability, Gorilla Glass is an artificially strengthened material, made by dipping glass into a molten salt bath of potassium nitrate. Potassium ions in the salt bath diffuse into the glass, creating a hardened compression layer on the surface.

Although the concept has been around since the 1960s, and Gorilla Glass has been marketed as a brand by Corning since 2011, the technology has been linked to Apple since the iPhone’s beginning. When Steve Jobs began looking for a glass manufacturer for the iPhone in 2006, he spoke with a former Xerox PARC friend named John Seely Brown, who was on Corning’s board of directors. Brown advised Jobs to speak with Corning’s young and exciting CEO, Wendell Weeks.

This began the long relationship between the two companies. As Walter Isaacson revealed in his biography of Jobs, Weeks told the Apple CEO that Corning didn’t have the facilities to make the kind of type of material Jobs sought.

“Don’t be afraid,” Jobs said. “Get your mind around it. You can do it.”

Photo: Corning
Gorilla Glass 4 is Corning’s toughest material yet. Photo: Corning

Less than six months later, Corning was in the Gorilla Glass business.

In the early days, Corning was in an enviable position. Most companies making screens for smartphones were doing so out of plastic, a material that was deemed unsuitable by a perfectionist like Jobs. “Folks realized pretty quickly that plastic scratched easily and looked terrible after even minimal usage,” says Corning’s Velasquez. “Smartphones were getting better and better, but the first thing people look at tends to be the screen. That’s where we came in.”

The first few generations of iPhone featured Gorilla Glass. In 2012, Corning introduced Gorilla Glass 2, which was even more resistant to damage. The year after that, Gorilla Glass 3 hit the scene. Corning had changed the composition of the material at the atomic level, strengthening the bonds which held Gorilla Glass together.

Corning’s biggest challenge to date came late last year when Apple signed the deal with GT Advanced Technologies, helping set up a factory that was to be used for creating sapphire displays for next-generation iPhones.

“My understanding is that both new iPhone models were supposed to have sapphire displays,” says analyst Matt Margolis, who has written extensively about sapphire. “The bigger you go with a phone the more of a risk breakage becomes, which is why Apple was keen to use sapphire, since it’s known for its resilience.”

It only became apparent that sapphire wasn’t going to be ready for prime time around June of this year. By then it was clear that sapphire was both too expensive and too unreliable for what Apple had planned.

Had Cupertino consulted with Corning about its dalliance with the sapphire manufacturer, Velasquez hints that the Gorilla Glass maker would have been all too happy to share its experience with the sapphire manufacturing process.

“We’re very familiar with [sapphire] crystal growth,” says Velasquez. “We’ve made a lot of it in our history.”

“Corning has been really defending their product since the whole Apple deal with GT broke last November,” says Margolis. “In particular, they talked about how sapphire was 10 times the cost of Gorilla Glass, which in the end turned out to be very accurate.”

While GT Advanced Technologies was going down, Corning was perfecting Gorilla Glass 4, made using the company’s proprietary fusion draw process. To create it, Corning scientists looked at hundreds of broken devices and discovered that the main cause of field failures is sharp contact drops, accounting for more than 70 percent of breakages. The team working on Gorilla Glass 4 created new drop-test methods to simulate real-world smartphone disasters, and the company claims the substance will pass meter-high drop tests approximately 80 percent of the time.

This new development hasn’t just been innovation for innovation’s sake. Phones have gotten bigger and thinner, necessitating stronger displays. On the iPhone 6 and 6 Plus there is virtually no cushioning around the bezel, meaning it’s even more likely that a single drop will prove fatal. By comparison, the original iPhone looks like an armored tank.

“The trends that we’re currently seeing in smartphones — larger screens, thinner form factors, more aggressive design — are all decisions that make it more challenging to deliver a cover glass that will survive these drops,” says Velasquez.

Corning won’t disclose the total volume of glass it is able to produce in any given year, nor will it reveal whether the just-announced Gorilla Glass 4 is being used in the iPhone 6 or 6 Plus. Margolis suggests it isn’t, and famously secret Apple did not respond to Cult of Mac’s inquiry on the matter.

If that’s so, Corning has an ace up its sleeve for the iPhone 7, should Apple flirt with a sapphire screen again. Right now, Corning is touting Gorilla Glass 4 as the world’s most exciting and durable smartphone display material.

That should keep Corning ahead of the upgrade curve — at least until the next sweet young thing strolls onto the market.

“The next big challenge to Gorilla Glass is going to be sapphire laminate,” predicts Margolis. “This is a similar process, in which a thin layer of sapphire is added to glass to make it scratch-resistant. Unlike pure sapphire, this material would be very close in price to Gorilla Glass.”


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