Sapphire versus Gorilla Glass in smartphones?

Sapphire versus Gorilla Glass in smartphones? Corning saysno contest but GT Advanced Technologies disagrees

Edited By Peter Wray •May 23, 2013

There have been many gains in theproduction and application of sapphire over the last decade, but one newapplication being pursued—cover and touch screens for smartphones and similardevices—has certainly surprised me and is generating some controversy over itscommercial feasibility.

Most of the discussion aboutsapphire can be traced to GT Advanced Technologies (GT), a Nashua, N.H.,company. Back in March, GT had a booth at the Mobile World Congress 2013show in Barcelona, Spain, where it had a demonstration of aniPhone 5 where the Gorilla Glass 2 (GG2) front cover had been replaced withsapphire (see video above).

I mention the GG2 onlybecause the state-of-the-art glass is Gorilla Glass 3, whichhas three times the damage resistance of GG2, a huge improvement in an alreadygreat product. GG3 is just now debuting on the new Samsung Galaxy S4, and Isuspect GG3 will show up in the next generation of iPhones, but Applenotoriously will never admit it.

Now, there is no getting around thatsapphire is a wonderfully tough material, as demonstrated by its use inmilitary transparent armor, critical optics (including many of the tiny cameralenses in smartphones) and high-end watch faces. And, I am sure that a sapphiresmartphone would highly resist scratching, but … my personal opinion is thatthe scratching concerns, whether from car keys or sand or whatever, are highlyoverrated.

My first iPhone 3 fell out of myshirt while I was cycling down California’s Mt. Tam at about 40 mph. As Ilooked back, I saw the phone skidding and tumbling about 50 feet through thegravel on the shoulder of the road. When I retrieved it, it was face down. Iexpected the worse, but there was nary a scratch. Nowadays, I stuff my phone inthe same pocket with my keys all the time, and I have tossed it into a lot ofbeach bags with sand.

There still isn’t a scratch on myphone, and I have yet to see one that does, although I am sure it happenssometimes. But I have seen no evidence that scratches are a major shortcomingof Gorilla Glass. (Smearing and difficulty seeing in direct sunlight seem to bebigger problems). I should point out that I am differentiating between scratchesand cracks. I have seen several smartphones with the latter, and whilescratches can lead to cracks—more on this below—cracks frequently come fromimpact damage when a phone is dropped on an exposed edge.

Regardless of my anecdotalexperiences, sapphire has some definite knocks against it. The material may bevery hard, but unlike glass, I know of no way to introduce compressive stressto sapphire. No alkali ions can be introduced to sapphire to “pack” the surfacethey way that a chemical treatment, for example, does to glass. These ions giveglass its retained strength after damage and are what keeps damage, evensmaller than visible scratches, from turning into a full-fledged crack.

Perhaps more importantly from abusiness standpoint, it would seem that the process of making sapphire is costprohibitive compared to Gorilla or other glasses that can be made in a rapidcontinuous process. I’ve written before about some of the most advancedprocesses, but making sapphire still requires pulling single boules of crystal,inspecting the boules, sectioning the boule into “good” and bad sections (the diamond wire saws create more waste). After that, onemust polish each sheet, a process that can introduce flaws. Criticsalso say that sapphire will have to be considerably thicker and heavier thanGG2 or GG3 and may have glare problems. The video below, although apparentlymeant to be laudatory, illustrates most of these drawbacks, and the processesstands in sharp contrast to Corning’s continuous and highly automated methodfor making GG.

Corning is hardly unbiased, but itrecently publicly expressed its doubts about sapphire. Although sapphiresupporters probably see a victory in the fact that Corning has responded atall, a new press release describessapphire as “not a major threat.” A company VP, Jeffrey Evenson, says, “Whatwould people say if someone invented a cover that was about half the weight,used 99 percent less energy to make, provided brighter displays, and cost lessthan a tenth of sapphire? I think they’d say that sapphire was in real trouble.It so happens that we at Corning already invented that cover—and it’s calledGorilla Glass.”

GT, however, seems serious aboutpromoting the idea of using sapphire in consumer touch screens. This week, thecompany is doing additional demonstrations and presentations atthe 2013 Society for Information Display’s Display Weekevent in Vancouver, B.C.

In news release about appearing at theSID meeting, GT counters doubters, saying, “The presentations willhighlight results of recent sapphire material testing and provide an update onthe progress being made in the development of an optimized fabrication valuechain for delivering low-cost and high volume sapphire screen material.GT is developing and investing in a number of innovative technologiesthat, when commercialized, will help to lower the cost of sapphire coverscreens to levels that are competitive with reinforced glass material.”

GT also has been buying up somemanufactures of advanced sapphire-making equipment. For example, last week itannounced that it had purchased the Santa Rosa,Calif.-based Thermal Technologies. Tom Gutierrez, GT’spresident and CEO says, “The acquisition of the Thermal Technology businessadds a number of innovative and important products and technologies to ourrapidly diversifying portfolio that will, we believe, allow us to accelerateour entrance into new markets.” Likewise, GT has been announcing some sales agreements with purchasers ofcrystal-making equipment.

All of this begs the question, IsGT’s business plan to make and sell sapphire touch screens or generate interestin sapphire among touch screen makers in order sell them sapphire-makingequipment? I suspect it is the latter. I tried to get clarification on this andmany other questions from GT but as of this writing, I have not heard back fromthe company.

Will GT be successful? MITTechnology Review’s Kevin Bullis, a writer I greatly respect, seems alittle more open to the prospect than I am, and his column about GTis worth a read.

Meanwhile, I am definitely in thecynic category. It’s not just about the inherent weaknesses of sapphire in thistype of application. To be successful, you have to have both superiortechnology and the capability to deliver the product in large volumes atcompetitive prices. There is uncertainty about the former, and GT cannot do thelatter. It is worth remembering that Steve Jobs’ biggest concern about GorillaGlass wasn’t the technology—it was whether Corning could deliver it in theamounts that Apple thought it could sell, and even then, Corning had tobasically drop everything to get the orders filled.

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