Corning Gorilla Glass puts glass through the ringer
The company’s engineers and technicians test thousands of glass samples every year, with an end goal of creating the most durable, innovative cover materials possible.
At the Corning® Gorilla® Glass testing facility, phones are dropped, slapped, tumbled, poked, and scratched – mimicking everyday ordeals like a phone hitting pavement or surviving the depths of a bag with personal effects like keys or coins. Only the toughest cover material can make it through.
But that level of testing is to be expected for a material that covers billions of devices across the globe.
“There’s never a dull moment,” says Ben Egboiyi, Sr. Manager, Reliability Programs, who has personally tested thousands of samples of Gorilla Glass.
Ben Egboiyi tests samples of Gorilla Glass to ensure it can survive the rough and tumble of everyday life.
Corning has released multiple generations of Gorilla Glass since the first generation of the cover material in 2007. In between these releases, Corning employees are hard at work in the testing lab.
“It’s all about continuous improvements through innovation and addressing the real failure modes that are happening in the field,” says Kevin Reiman, Director, Application Development and Reliability, who has been part of the Gorilla Glass testing team since day one.
Gorilla Glass embeds this field of compression deep enough into the cover material to help prevent surface-level flaws from developing into more severe breakage.
Why do phones need glass?
For decades, mobile phone producers mainly covered the displays of devices with plastic. But there are key problems with plastic display covers: they scratch easily, lack optimal touch responsiveness, and can lose clarity over time.
To help solve these issues, Corning leaned on its expertise in glass.
The whole idea behind Gorilla Glass is to create a thin, yet durable, glass that can provide a clear display and survive the rough and tumble of daily life.
After the glass is constructed, it goes through Corning’s proprietary ion exchange process, which replaces smaller ions with larger ions, strengthening the glass.
“The ion exchange process imparts a compression on the surface of the glass, so that when you have a flaw that gets introduced from a drop or a scratch, it’s squeezed closed,” says Jon Pesansky, Director, Product Reliability Technology.
With this layer of compressive stress, the glass gains the strength to better withstand drops and scratches.
Gorilla Glass embeds this field of compression deep enough into the cover material to help prevent surface-level flaws from developing into more severe breakage.
A “puck” awaits its drop at the top of a testing tower.
How is Gorilla Glass tested for durability?
Gorilla Glass represents Corning’s unwavering commitment to continuous innovation. The company’s constant testing of Gorilla Glass is both a science and an art, Egboiyi says.
"Testing requires a lot of rigor – constant studying, tweaking, and innovation, just like what we do with coming up with new materials,” he says. “And coming up with new tests is as important as coming up with new materials.”
Reliability researchers run thousands of tests.
Drop Tower
A drop is by far the most common reason for screen breakage.
The Gorilla Glass team knows this because it collects phones whose screens break or “fail” out in the world and analyzes these devices. Corning then uses these findings to help develop next generation cover materials and solve customers’ tough technical problems.
"We look at how the glass is breaking, but also the characteristics in the phone. We're constantly trying to understand how the phone design is contributing to how the glass is performing,” says Jonathan.
To meet this failure mode head on, Gorilla Glass staff began testing cover materials using the “drop tower,” which has become the most well-known Gorilla Glass test, thanks to YouTube.
The drop tower simulates real world drop events by using sandpaper to replicate hard, rough surfaces, like concrete or asphalt. The drop tower allows Corning teams to evaluate the performance of potential new versions of Gorilla Glass in a controlled environment.
Via the drop tower, Corning-designed drop test vehicles (or “pucks”) are raised with metal jaws and then dropped multiple times to see at what height and number of drops the glass survives, on average.
“With our customers, one of the first questions they will ask is, ‘how is the drop performance?’” says Kevin. “We have that data ready for them.”
Researchers test both in-development cover materials (using demo pucks) and devices already on the market.
“We used to go buy like 100 phones at a time when a phone would come out,” says Pesansky. “We still do that sometimes, but we also make ‘pucks’ so we can test a material without using an actual device.”
Pucks mimic the form factor of a phone in both weight and localized bending and can be dropped and rebuilt as needed over and over again.
The slapper test helps Corning demonstrate to customers how a device will handle drops.
The Slapper
The Gorilla Glass testing lab also features a device called “the slapper,” which Ben, Kevin, and the team created in 2016. The slapper mimics a drop event, albeit in a more controlled setting than what’s offered by the drop tower. The slapper pre-stresses the glass, simulating how a phone will flex when it hits the ground in a drop event. The pre-stressed glass, fixed to the end of a mechanical arm, is then slammed onto a rough surface.
By using different lengths of slapper arms, Corning teams replicate the force of drops caused by various heights.
Since its invention, the slapper has served as an excellent tool for demonstrating to customers how a phone can handle drops.
The tumbler
The tumbler test places a puck in a rotating, dryer-like machine with objects someone might carry daily, like makeup cases, pens, keys, and coins. This test mirrors the types of scratch events a phone might be exposed to in a bag with other personal belongings. Lab staff analyze the condition of the cover material once it’s gone through the tumbler for a few cycles.
The scratch test makes intentional scratches to see how glass can withstand everyday micro scratches.
The Scratch Bot
In 2024, Corning debuted the “Scratch Bot,” a lab test designed to replicate the frustrating micro scratches caused by day-to-day wear. The Scratch Bot uses weighted indenter tips outfitted with sandpaper to make scratches on the surface of glass samples.
There’s never a dull day in the reliability lab, where you’ll see phones in mid-air all the time.
Measuring the minute flaw for the bigger picture
These are just a few of the multitude of tests the Gorilla Glass business uses to evaluate the performance of cover materials. In the Gorilla Glass world, minute details, down to the micron level, matter. The tests not only demonstrate the strength of the latest generation of Gorilla Glass cover materials, but also indicate a path forward for future material science innovations.
It’s a team effort, Kevin says.
“It's important that consumers know that this team is focused on ensuring that their experience is as positive as can be,” Kevin says. “Everyone drops their phone. We want the survivability to be as good as it can possibly be.”
