Tony Tripeny, senior vice president of Corning Glass, launched a critique of sapphire crystals as materials for displays at a Q&A session recently at the Morgan Stanley Technology, Media & Telecom Conference. The response given by Mr. Tripeny was a repetition of Corning’s disapproval of sapphire crystals from earlier months.
James Fawcett asked Tripeny about sapphire versus glass now that “there is one large handset and device maker that people suspect maybe looking at Sapphire.” The large manufacturer he was referring to was obviously Apple, which is building a plant in Arizona to manufacture sapphire for “a secret project,” possibly the iWatch or the next-gen iPhone. Tripeny didn’t hold back in his criticism of the sapphire crystal material, he stated the following:
When we look at it, we see a lot of disadvantages of Sapphire versus Gorilla Glass. It's about 10 times more expensive. It's about 1.6 times heavier. It's environmentally unfriendly. It takes about 100 times more energy to generate a Sapphire crystal than it does glass. It transmits less light which it means either dimmer devices or shorter battery life. It continues to break. I think while it's scratch resistant product it still breaks and our testing says that Gorilla Glass, about 2.5 times more pressure that it can take than Sapphire on. So when we look at it, we think from an overall industry and trend that is not attractive in consumer electronics.
The formation takes about 4,000 times longer than Gorilla Glass at a significantly higher melting temperature. Its hardness makes machining more difficult and costly. Then the cost per unit increases exponentially because when you have defects in boundaries in the crystal growth process, you essentially cut them out and so unlike glass where we have developed technologies so that we can have very large pristine pieces of glass, when you have that on crystals, what you end up doing is always having a yield issue. So it is really those items that make things more expensive.
Source: CNET, Seeking Alpha via MacRumors