“When we first said we had to fold our phones, everyone laughed. The next time, when we said they should be water resistant, we were told that was not possible, ”said Byengseok Choi, senior executive of Samsung’s product planning group, laughing.
As the Galaxy Z Fold 3 and Galaxy Z Flip 3 have since demonstrated, Choi’s critics were wrong. But getting there was not easy. Digital Trends spoke with Choi and two other members of the team tasked with strengthening Samsung’s foldable smartphones to find out how they did it.
The team had to develop new materials, new processes and even new test equipment to strengthen the new foldable smartphones. But they were also inspired by very familiar places. Here’s what it looked like behind the scenes.
“Our job is to make the impossible possible, which I believe is what we usually call innovation,” said Choi, who has been involved with the company’s foldable project since its very beginnings in 2005, although before we start hearing about it.
When Samsung first started developing foldable phones, a consumer survey found, perhaps unsurprisingly, that durability was a major demand. Despite the challenge involved and the initial reaction to the project, the Choi team went out of their way to make it possible.
“We have made a lot of effort to achieve this,” he said. “To be precise, we focused primarily on the exterior, display and adding water resistance. The most anticipated feature was water resistance, but a foldable has two parts connected by a hinge and wiring. Because of this structure, enabling water resistance is all the more complicated.
Resistance is not in vain
Waterproofing a phone is simple: seal it. Waterproofing a foldable phone isn’t: you basically have to waterproof two phones, as well as the intricate tangle of moving parts that connect them. Hee-Cheul Moon, senior engineer at Samsung’s Advanced Mechanical R&D group, divided the problem into several pieces, with different solutions for each.
“There are three main concepts for making the whole device waterproof,” says Moon. “We made the screen waterproof, the body parts of the device and the hinge waterproof, and then combined them using new materials we developed that make the connections and spaces waterproof. It is basically a sealing technology, and to achieve this we use different approaches: taping, gluing and layering. “
The overlay was used to waterproof the screen. “Even though there is a little water entry, the layers still protect the device,” Moon said. . If you understand this concept, you now have a basic understanding of how technology works. We surround each layer with bonding materials, so that each one is sealed.
The second step was to make the hinge water resistant, which at first glance seems even more problematic than sealing the screen.
“It’s actually easier than you might think,” Moon said with a smile. “We cycle in the rain, and they mostly consist of two wheels and a chain, which are all moving parts. What we used [on the Z Fold 3 and Z Flip 3’s hinge] is a specially developed lubricant that would guarantee the water resistance of the pliable until the end of its service life.
But what about the wiring that connects the two parts to each other? The lubricant can act on the hinge itself, but behind it, water could easily get into the rest of the device through the spaces used for electrical connections. Samsung first replaced the physical wiring with a flexible printed circuit board, and then developed a special silicone-like bonding material, which seals the spaces between the FPCB and the chassis. The result? The team got an IPX8 rating for both foldable smartphones, which means each will withstand around 30 minutes in freshwater at a depth of around five feet.
How about adding dust resistance?
“When we first released the Galaxy Fold, we went through a rough patch with foreign substances entering it,” Moon recalled, referring to the delays experienced by the first device in 2019. “We started from there. there and asked, ‘How can we stop this?’ We have opted for sweeper technology.
This breakthrough came from another type of product made by Samsung. “We tried 99 different directions and approaches to achieve our goal, and the clue we got was from the vacuum cleaner. The sweeper’s bristles protected the space between the hinges and after a few tries the concept turned out to be effective. But the hairs must have been much smaller [than those used on a vacuum cleaner]So we had to develop this technology, new materials, find the optimal structure and make the whole production work as well.
We tried 99 different directions and approaches to achieve our goal, and the clue we got was from the vacuum cleaner.
Despite these advances, the X in the IPX8 rating indicates that neither the Z Fold 3 nor the Z Flip 3 are dust resistant, unlike phones with an IP68 rating. Why not? “Simply put, at the moment, to be realistic, that’s not possible,” Moon said. However, he conceded, “consumers are right to ask, and we are constantly improving sweeper technology to achieve this goal.”
With the interior of new foldable smartphones protected, what about the exterior? Samsung introduced Armor Aluminum on the new Z Fold 3 and Z Flip 3, which are used for the frame and cover on the hinge. Sung-Ho Cho, senior engineer at Samsung’s Advanced Color, Materials, Design (CMF) lab, has years of experience working with CMF on Galaxy devices at Samsung. He joined the team in 2006 and went on to work on the Galaxy Tab, Galaxy A, Galaxy Note and now the new folding hardware. Durability and aesthetics, he explains, don’t always go hand in hand.
“Creating a strong material is the easy part, but the result may not work for everyone involved, making development a difficult balancing act,” Cho said. “You can make a new material as tough as you want, but there’s always a trade-off. Finding the balance between strength and conception, from a CMF perspective, is the hardest part. For example, if we want to make the material stronger, maybe we won’t get the color we want. “
Samsung spent almost two years developing Armor Aluminum. Cho said the most effective way to assess the toughness between different materials is to strike them together. He showed me a comparison between Armor Aluminum and other metals, again with Armor Aluminum experiencing the smallest bump, suggesting that Samsung found the balance it was looking for.
Robustness and feel of the screen
The exterior of the Z Fold 3 and Z Flip 3 is more durable and the interior will not be damaged by water, but what about the final look, the screen? Cho said the team worked on two main areas to make the display stronger. The first was to experiment with different layers of panels to find the structure with the greatest impact resistance, and the second was the protective film that covered the top.
“A new material has been developed for the film that stretches better so as not to damage the screen and does not affect the experience when folding and unfolding,” Cho said. “As a result, we achieved an increase of over 80% in the durability of the panel: it is more resistant to bumps and distortion, more transparent and attracts fewer fingerprints on the screen. “
When using the Galaxy Z Fold 3 and Z Flip 3, it’s surprising how much glass the screen protector looks like, especially compared to the original Galaxy Fold.
“The film is the same material as our bar-type phones,” Cho revealed, “so it naturally feels the same when you touch it. But we had to improve the stretch properties so that it was more suitable for foldable phones.
Test new devices
How do you make sure all of these wonderful materials work in the real world? Samsung couldn’t just trust the existing tests.
“We had to develop completely new equipment and testing processes,” Choi said. “For a foldable, special equipment is needed to test the overall durability, not only for drops, but also for folding actions. For the new drop tests alone, we had to develop three different kinds of machines to make them work, and the waterproof test is also completely different for the foldables. Because [folding smartphones are] a new category, we had to develop them all from scratch; all tests, processes and equipment.
Teamwork and the future
Samsung is at the forefront of smartphone folding right now, but it wasn’t easy to get ahead – there were no hard and fast rules to follow, very few proven methods or processes, and not even always. the right equipment for the job at hand. It’s fascinating to understand a little about what makes these cutting-edge devices possible and better than the ones that came before.
“What we’re most proud of is that three parts of our production had to work together to make this all possible,” Moon said. “First, you start with an idea, second, you need to combine them with the right architecture and design, and third, you need a systematic and structured installation and production process to enable production of coherent mass of the device. “
Some may think this is only really possible due to Samsung’s size and manufacturing power, but while it is sure to play a role, Moon knows there is something more to it.
“It’s not something about the size. It’s our team, ”he said proudly. “We put together a fantastic team and we really made it happen,” he said of the challenge of producing sustainable foldable smartphones. “Because we’ve come to this, I think we can be even more innovative in future versions of our foldable products. “