Your next smartphone might use sapphire glass instead of Gorilla Glass | Hacker News Reader

Your next smartphone might use sapphire glass instead of Gorilla Glass

extremetech.com

I have a watch with a sapphire glass face. I must say, I have always been impressed with its scratch resistance. Nothing I have done so far has scratched the glass, and it's coming up on ten years. It's not from babying the watch either, because the stainless steel bezel has developed quite a few marks.

Interestingly, if you want to know whether something you own is sapphire glass, you can usually conduct a simple experiment:

Drop some water onto the glass face, and jostle the item around a bit. If the water stays put in a semi-uniform droplet, regardless of the motion and angle, it's probably sapphire.

Sapphire has been used for watch crystals (and increasingly for case backs) for quite a while now. My "precious" digital camera has a sapphire cover on the LCD.

It's interesting what they're doing in terms of shapes beyond sheets and simple "lens" type constructions. I made a foolish watch purchase because the sapphire case back was especially compelling. (This isn't my video, but it's the same watch: http://www.youtube.com/watch?v=DxNgAXDDTgo)

I've wanted a camera lens made of sapphire front and rear elements, but the refraction index would require more custom engineering than it would be worth. Definitely more expensive than a few $10 UV filters. :-)

Can confirm it. few watches I had all been with sapphire glass and no scratch since purchase (10-15 years)

Only one watches have small blemish after drop of hot metal dropped on it while I was welding exhaust turbo manifold for my car. And even this one is tiny and adds nice touch to my watches :)

What I'm curious to know is, is it shatter or crack-proof? I don't know anyone who has "scratched" their phone screen but I see people all the time with shattered screens (or backs of phones) because they dropped their phone. To me it would be revolutionary if you could drop your phone without it cracking. "Cases" would be a thing of the past (and rightfully so).

So I imagine that most people when they shatter the glass on their phone its because of compression of the glass. I found this http://abrisatechnologies.com/docs/AT%20Specialty%20Glass%20... that says gorilla glass has a compressive strength of 800 MPa, and this http://www.roditi.com/SingleCrystal/Sapphire/Properties.html says that sapphire has a compressive strength of 2.0 GPa.

Additionally the flexural strength of sapphire appears to be ~20x higher then any of the "bending strengths" listed in that pdf

I'm afraid of shattering from dropping the phone. Does that translate into a compression? Or something else? (vibration?) Honest question.

For common uses of "shatter" and "crack", yes, sapphire can.

I've scratched the crap out of my 4s and 5 glass by forgetting "left pocket phone, right pocket keys" on too many occasions.

Are you talking about iPhones? They're not sapphires.

Sapphires are commonly used in watches. Not the cheapest watches, but any watch more expensive than a few hundreds typically has a sapphire glass.

That's why I mentioned glass. The parent stated «I don't know anyone who has "scratched" their phone screen.»

The parent also asked if sapphire could be shattered or cracked. My response to both comments is probably what confused you.

Plastic doesn't shatter.

Pretty much any solid can shatter if enough force is applied.

Case in point: Take a frisbee, lay it on the ground, and smash it with a sledgehammer. It will break or burst suddenly into pieces, i.e. shatter[1]

[1]http://www.wordnik.com/words/shatter

I can't believe no one has mentioned this already, but Mr Scott can now have his transparent aluminium.

Sapphire is aluminum oxide. The transparent aluminum you're talking about was invented in 2009.

I know it's not exactly the same, but I couldn't resist the temptation.

Not exactly the same? It's not at all the same. It's like calling oxygen (O2) "not exactly the same" as water (H2O), but you couldn't resist because they're both mostly transparent.

Never fear, alumin(i)um oxide is harder than elemental aluminum and is actually what you interact with outside a vacuum.

Work with me here guys... You're spoiling the joke.

Sapphire glass is already used on Vertu's phones...although the author probably didn't notice due to the fact that nobody is that dumb.

Vertu still exists? What do you mean by "that dumb"?

Nokia sold Vertu to a private equity group last year[1]. "That dumb" means who in their right mind would pay $10k for a phone[2]? Unless they were Kanye West[3]. And even he's an iPhone user[4].

[1] http://www.eqt.se/en/Portfolio/Companies/Vertu/

[2] http://www.forbes.com/sites/jonmatonis/2013/02/21/silent-cir...

[3] http://rapgenius.com/38105

[4] Or at least was in 2010. http://www.vulture.com/2010/11/in_the_studio_with_kanye_west...

Vertu's theory was that people who'd pay $10k for a watch (or, say, a painted cloth square) would be willing to pay $10k for a phone. I'm interested to hear that they've been successful enough at that to interest a private equity group.

Fly through Dubai. The airport mall kiosks sell Vertu phones.

Vertu → Nokia

I hope I am not asking a dumb question but would there be any complications with capacitive touch using sapphire glass over currently implemented gorilla glass? The video didn't demonstrate actual phone usage with the sapphire glass overplayed on top of the phone.

Wondering the same thing as well, and I've worked on capacitive screen design. The dielectric constant of sapphire seems to be better than glass[1] for this type of application, so it should be okay.

[1] http://www.st.com/st-web-ui/static/active/cn/resource/techni...

>>There’s one caveat: according to a market analyst, a sheet of Gorilla Glass costs around $3, while the same piece of sapphire glass would cost $30

I'm already paying a lot of money for the smartphone what difference does it make another $30-$50 dollars. Especially considering that is far more expensive to replace the screen of the phone and in a lot of cases you'll have to replace the entire phone which will cost you a couple hundred dollars.

$30 extra in the bill of materials probably means an extra $50 in the wholesale price. And that means and extra $100 in the retail price. Which would result in significantly lower volumes, and start a feedback cycle that'd further raise prices.

extra $100 in the retail price amortized 24 months = $4/month on a cell plan that subsidizes the phone purchase.

even less when you prorate the difference in retail price by the "up front" cost of the phone ($50 or $199 or whatever)

Admittedly this is the most unscientific of sources, but this Yahoo Answers -ducks- post claims Sapphires have a hardness of 9 out of 10, where 10 is diamond. That leads me to believe it'd be harder to crack than glass.

I believe hardness has more to do with scratching than cracking; e.g. plastic is harder to crack than glass, but softer.

Indeed, cracking is generally inversely related with hardness. Harder things are easier to crack than softer things.

Sapphire has, by definition, 9/10 on Moh's hardness scale. http://en.wikipedia.org/wiki/Mohs_scale_of_mineral_hardness

(Sapphire is just Corundum that isn't red or pink)

Specifically, it's corundum that's blue because it's got titanium and iron impurities. Anyone trying to sell you a "white sapphire" (or this "sapphire" glass) is trying to pull the wool over your eyes. I can see why, though - it's an easier sell than calling it just corundum.

wyager and svachalek are right, but the 9/10 harness was confirmed by the OP video. It's pretty darn scratch resistant.

Hardness only determines how difficult something is to scratch. Resistance to cracking is much more complex. For example, I could easily smash a diamond with a steel hammer. But I could also use that diamond to slowly grind the hammer to dust.

Sandpaper can scratch sapphire, as it is made of particles of carborundum. Same with some stone garden furniture. Sapphire is quite brittle: it has lower shock resistance than glass, that's why quite expensive sports watches use some kind of glass, or plexiglass (famously, the Omega Speedmaster selected for the Apollo had a hesalite crystal).

I'd be happy to pay an extra $27 for this. No more screen protectors needed. Alumina is harder than most metals.

The problem there is it's an additional $27 on the manufacturing BOM cost (or possibly $54 for an iPhone with front and back glass). By the time all the markups on the way to the retail store get applied to that you'd be looking at more like ~$90 extra, or $180 for both sides on an iPhone.

(Markup estimate based on BOM cost and Retail pricing here: http://www.isuppli.com/Teardowns/News/pages/iPhone5-Carries-... )

The unibody machining costs back when the MacBook Air first came out was pretty ludicrous too - $1800 for a MBA if I remember correctly.

Now it's $900, and the same process has been streamlined to the point where even mid-range phones have this sort of construction.

We just need someone to lead the charge.

The sapphire is susceptible to chipping or shattering if whacked hard enough or dropped (a bit like toughened glass...hardness usually means more brittle). Diamonds are the main cause of scratches, but softer materials can also still cause scratches....

Anyone wanting to learn about what could come after what comes after should read up on transparent spinel specifically.

http://en.wikipedia.org/wiki/Transparent_ceramics

My problem with current screens is that they functionality exceptionally well as mirrors first, and then also display some stuff through the reflections as secondary functionality. I really wish they would fix that first.

But shiny screens bring more attention at retail store.

Couldn't read the article. Half way through a paragraph on their faux-swipable layout you are shown a full screen ad for some movie comparing the White House to Olympus.

That's Onswipe, and it's my least favorite thing about browsing the web from a mobile device lately. It's slow, the ads have become really irritating recently, and there's no way to preemptively tell a site you don't want to use it.

A bit ironic, if I read it right Gorilla Glass has a (Mohs hardness) of about 7 or 8.

Aluminum is about a 6 but oxidized luminum is corundum/sapphire is about a 9.

The one thing you may have had in you pocket, oxidized aluminum object, will now be the entire screen.

Actually sapphire is NOT "the hardest natural substance after diamond". Moissanite seems to be. It has a hardness of 9.5/10 (sapphire: 9/10) and occurs naturally, but can also be produced technically.

Are industrial diamond screens also a possibility?

Since diamond is harder than sapphire, they would seem a better choice, but maybe there are other drawbacks.

There's a very good reason to use sapphire: since it has a (slightly) lower hardness than diamond, you can cut it into sheets with a diamond saw.

Sapphire still has a very high hardness, much better than glass of any sort.

If we fast forward 20 years, I wonder if we could be a graphene 'sawing' diamond?

Graphene's just a one atom thick sheet of graphite ;)

(Source: I research graphene.)

Given that much of Graphite's weakness is due to sliding sheets, I was under the impression a single sheet would be far stronger?

Are they making diamonds that large?

Artificially, sure why not, its just compressed carbon.

It's (quite) a bit more complex (and expensive) than that. You can't just push a lump of carbon really hard into a sheet. You have to worry about all sorts of things to get a high-quality crystal, and making crystals that are both optically high-quality and large is very expensive.

This was solved 50 years ago. Interesting read: http://www.pbs.org/wgbh/pages/frontline/programs/transcripts...

What was solved 50 years ago? Just because we can make synthetic diamonds does not mean we can make synthetic diamonds of any arbitrary size or quality. In fact, it becomes exponentially more expensive in proportion to the volume of the produced diamond. Most artificial diamond companies limit mass to 2-300mg per diamond because it gets much more expensive after that. Of course, we are speaking of optical-quality monocrystaline diamonds here. Polycrystaline diamonds are less expensive, but unsuitable for optical equipment (e.g. cell phone screens).

That's not to say the problem is hopeless; in fact, there has been some very interesting research done in recent years on low-pressure microwave-based diamond synthesis that could allow for very large, kilocarat-scale diamonds. But for now, it is not feasible (as far as I know) to produce diamonds in the shape and size needed for cell phone screens, and certainly not at low cost.

Still cheaper to manufacture diamonds than to mine them.

If your idea of the cost to mine diamonds is inspired by its retail price, you would be surprised to discover that the retail price is totally artificial. The markup is astronomical. Also, diamonds are not at all rare.

Google says maybe?

http://www.diamond-materials.com/EN/products/overview.htm

http://www.e6cvd.com/cvd/page.jsp?pageid=298

The prices are a bit high: a 0.8 cm diamond optical window goes for $450, for example.

Hmm, they offer discs up to 12cm [0] in diameter. However they are made using "the chemical vapor deposition technique allow[ing] the synthesis of diamond in the shape of extended disks or wafers. Under optimized growth conditions the properties of these disks approach those of perfect diamond single crystals."

I wonder if how the mechanical properties compare to single crystal diamonds.

[0] http://www.diamond-materials.com/EN/products/disks_films_mem...

Diamond is hard, but it's very brittle.

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