"When the [sapphire] area is larger, with the increased hardness, it takes more aggressive abrasives to grind and polish it," says Jennifer Stone-Sunderberg, who has a Ph.D. in solid state chemistry and crystal growth, and now consults in this field as a managing director of Crystal Solutions of Portland, Ore. "It's time-consuming to polish something that hard."
Secondly, it means overcoming a surprising problem: despite its hardness, synthetic sapphire can be prone to fracturing, at almost any point in this finishing process, due to impurities or to the presence of unresolved strains in the crystalline structure.
"That's something that's being very carefully measured and tested," says Stone-Sunderberg. "Fracturing is probably of the highest concern. If a product is released with a more expensive touch screen [cover] and consumers experience fracturing, they're going to be highly disappointed. It would be devastating to the sapphire industry."
Tackling these issues on this scale and schedule has never been attempted before.~~
"GTAT and the rest of the Apple supply chain involved in this new sapphire component indeed have to execute an unprecedented - for the sapphire industry - ramp up, both in term of scale and timeline," says Eric Virey, senior market and technology analyst for LED devices and materials at Yole Developpement, a market research firm headquartered in Lyon, France. "Execution will be key and a lot could go wrong. This ramp up is stressing the entire supply chain, including raw materials and component suppliers."
The big sapphire shift: from specialty to mass markets
Sapphire has been used in a variety of specialized applications for years, where its purity, clarity, high stable dielectric conductive properties, and high optical quality, along with its hardness, have made it worthwhile despite its relatively high price. It's been used in lasers, as covers for point-of-sale barcode readers at grocery store checkout aisles, in high-end watch faces, as the principal integrated circuit substrate for LED manufacturing, and more recently as a lightweight replacement for conventional "bullet-proof" glass in some military vehicles.
Some luxury smartphones, with luxury prices, have been released with sapphire covers, such as the new Tag Heuer Meridiist Infinity or the Vertu Ti. China-based Gionee early in 2014 was the first to release a barely-under $1,000 smartphone with a sapphire screen.
But no one has used sapphire in large-scale consumer electronics or consumer goods products. Apple created a sapphire cover for the iPhone 5 camera lens, and for the iPhone 5s Touch ID fingerprint sensor. It's mainly the sheer foundry capacity that Apple is creating in sapphire that fuels the speculation that it has big plans for sapphire in bigger uses as a replacement for the cover glass, presumed to be Corning Gorilla Glass, in at least the high-end iPhone model.
Sign up for CIO Asia eNewsletters.