From Extreme Heat to Half a Million Bends: An Extraordinary Look Inside Samsung’s Display Lab

In a private room inside Samsung Display’s headquarters in South Korea, rows of gray and black machines repeatedly fold, bend and stress test the company’s new mobile displays. During a visit in mid-June, I was among the first people outside the company to go step inside the high security lab and see how Samsung is pushing its foldable screens to their limits before they reach consumers.

On Tuesday, Samsung introduced Flex Titanium, a new display technology for its upcoming foldable Galaxy phones including the Z Fold 8. It combines a titanium-alloy film with a titanium plate to create a thin, rigid display designed to better withstand drops and other impacts — an important consideration for foldable phones that can cost thousands of dollars.

Samsung Display designs and manufactures screens for Samsung Electronics and competitors including Apple, and has become one of the industry’s leading developers of flexible and advanced display technology. Apart from commercial products, the company regularly shows display concepts of the future of phones, tablets and other devices.

Watch this: I Went Inside Samsung’s Secret Demonstration Lab and Saw Its Most Dangerous Phone Concepts

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As Samsung makes foldable phones thinner — last year’s Galaxy Z Fold 7 measured a surprisingly thin 4.2mm when unfolded — the company is looking at ways to shrink various components to maintain a sleek profile. Samsung says it spent nearly three years developing the Flex Titanium technology while testing customer feedback on seven generations of its foldable phones.

“We have to understand user behavior and various display challenges such as dropping or pressing with a large object or a small object,” Samsung senior vice president Byung Duk Yang said in an interview. “As a result, we developed a very comprehensive and sophisticated testing method to understand user behavior in the real world.”

Tests the durability of foldable displays

As we wandered through the maze-like, whitewashed streets below Samsung Display’s headquarters in Korea, about 20 miles from Seoul, our guide revealed the specifics of what we would be seeing. No one outside the company — not even the employee’s mother and father — has ever been here, he said as he led us to the checkpoint.

In this secluded, engineer-only room, machines work around the clock, folding and unfolding display panels to ensure they can pass 500,000 folding tests. When the metal latch is closed, the panels of the Z Fold 8 (there are currently four inside) are subject to high temperatures ranging from -20 degrees to 60 degrees Celsius (or -4 degrees to 140 degrees Fahrenheit).

Outside the device, a monitor shows what’s happening inside from eight different camera angles. The video, which is also recorded, can detect problems such as the lifting of the display on the frame of the device. Currently, the display panels being tested are closed, but the machine can test how performance displays react to extreme conditions, too.

Down another long hallway (I feel like I’m in an episode of Severance at this point), we enter a lab to test the display’s image quality, including brightness and color. After placing the display in the center of the machine and closing what looks like a small garage door with sliding windows to peek out, the test begins.

A series of light bulbs shines down on the panel, and a machine measures how much light is reflected — the less, the better. That’s for a few reasons: The display’s colors appear deeper, less glare makes it easier to see the screen under bright light and you’re less likely to stare into your glare when you look down at your phone. It takes about three minutes to scan one panel.

Some of the tests I’ve seen seem simple compared to these more in-depth technical mechanics, but are equally important to ensure the durability of the display. A 220-pound machine placed on a counter holds a marble-sized metal ball weighing 21 grams. The arm-like structure drops the ball from a height of 30 centimeters onto the display three times to ensure that it will not crack. In our demo, we pushed the limits to maximum drops from 40 and 50 centimeters, and the display absorbed and distributed the pressure well to avoid damage.

Making a “better display”

Samsung’s new Flex Titanium is all about durability without adding bulk. Compared to polymer film, the titanium-alloy film has 20 times the mechanical strength, the company says, which means it retains its shape better. This component sits below the OLED panel and is less than one-third the thickness of a human hair. Below that is a titanium plate, which Samsung says can provide stable support when the phone is unfolded without compromising flexibility.

Last year’s IZ Fold 7 also used a titanium plate, but the display structure is made up of multiple polymer-based support layers. Samsung has now combined those layers into a single titanium-alloy film, reducing the size of the display module while maintaining strength, flexibility and long-term durability, the company said.

See also: Beyond the Galaxy Z Fold: Samsung’s Future Phone Concepts That Roll, Slide and Expand

Notably, the improved display has a reduced crease — a growing focus in the world of foldable phones. Samsung Display showed off a foldable concept screen at CES earlier this year. The company is reportedly working with Apple to develop a flawless screen for the foldable iPhone, which would allow it to start falling. What I saw on the Samsung Display in June was still a small crease, although not as noticeable as the Z Fold 7’s.

Samsung is expected to share more about Flex Titanium with upcoming Galaxy foldable devices, including the Z Fold 8, during its summer Unpacked event on July 22. These developments appear to be a step toward reducing much of the durability and aesthetics that have long characterized foldable phones — though the work is far from done.

“Years ago, Samsung created this foldable category,” Yang said. “And the foldable display and the structure we developed became the standard. So we feel responsible for this market; we have to make a better display.”