Samsung is no stranger to catastrophic engineering failures and embarrassing product recalls. Not nearly long after shipping Galaxy Note 7 smartphones that quite literally exploded in consumers’ pockets, one can say that the South Korean conglomerate had it relatively easier with its latest product disaster.
The fatal engineering flaw with the Galaxy Fold smartphones was thankfully discovered in April this year by reviewers who were shipped evaluation units. This saved Samsung the ensuing embarrassment of undertaking a messy public recall all over again. The phone nevertheless was hit with a wave of negative publicity after select high profile reviewers documented the issues with their evaluation samples on social media not long before the official launch.
Understanding Three Potential Points of Failures in the Galaxy Fold
The Galaxy Fold has been Samsung’s most ambitious project for quite some time now, and could’ve been the first commercially available foldable smartphone, if it weren’t for the abrupt recall. However, the much-vaunted foldable displays of the early review units disintegrating within no time put a spanner in the works for the company.
With rumours of Samsung not being able to make its promised June re-launch date already making the rounds, the company is nevertheless hard at work trying to ensure that another public debacle isn’t repeated. Samsung might even have a solution at hand going by the its recent patent filings.
Over the course of the last month, Samsung has published three separate patents pertaining to foldable phone technology. Interestingly, each of these patents presents a solution to the three fatal flaws plaguing the Galaxy Fold review units that eventually forced Samsung to delay the launch and go back to the drawing board.
Let’s take a look at these design gaffes and how Samsung’s latest patents could solve the underlying problems that led to the devices being recalled before they even hit the market.
Flaw #1: Faulty Hinge Design
A flawed hinge design is a primary candidate in the Galaxy Fold debacle. On paper, the hinge looks over-engineered with an abundance of sturdy articulated metal joints, further streamlined with gears to make the process of opening and closing the foldable device smoother. However, some members of the media reported bulges in the foldable screen right near the hinge.
Although non-disclosure agreements may have prevented them from conducting a teardown of the phone to isolate and identify the cause of the problem, it is quite possible for a bad hinge design to have punctured the foldable display from inside out. A point of failure in the complicated hinge assembly can generate debris, which in turn can get caught in the gears and pushed into the display with enough force to puncture it. This was in line with the sort of inside out screen damage found in the early review units.
Solution: Simple Hinge that Doubles as Bend Limiter
This is where Samsung’s latest patent presents an elegant solution to this point of failure. The patent document details a deceptively simple design comprising of a multi-member hinge made up of multiple interlocking trapezoidal blocks. These blocks are connected to each other with pins, much like the links of a motorcycle chain, which allows the hinge to open and close without the need for gear assemblies and complicated machined parts.
Interestingly, the angle of the non-parallel sides of the trapezoidal blocks dictates how far the foldable display has to bend before the interlocking blocks meet each other. This allows the hinge to not only act as a means of articulation, but also serve as an effortless bend limiting layer. A bend limiting layer is indispensable for foldable devices because each bendable component, be it the foldable OLED display or underlying flexible PCB substrate, can be bent safely to a maximum prescribed radius without incurring permanent damage.
Samsung’s patent mentions how the trapezoidal blocks can be manufactured from rigid materials such as aluminium or high-strength plastics, with a coating of softer materials such as silicone or polyurethane to eliminate noise as well as wear and tear, while also making the mechanism feel smoother. The patent drawings depict the foldable display wrapped around the outside of device, which is a departure from general foldable design where the display is on the inside of the fold. However, there’s nothing preventing Samsung from using the same hinge on the Galaxy Fold, where the display folds inwards.
Flaw #2: Delamination of Flexible PCB
We have already examined how a complicated hinge with many moving parts is more likely to fail and can generate debris that can puncture the foldable display from the inside, as it was reported in the early review units of the now recalled Galaxy Fold smartphones. However, bending fatigue could have been a contributing factor towards the delamination of the flexible printed circuit boards (PCB) underpinning the Galaxy Fold.
This is another potential source for debris that eventually punctured the foldable display within the review units from the inside out. While traditional flexible PCBs can use substrate materials with higher elasticity for better resistance against bending fatigue, they are nevertheless limited by the copper traces within the PCB. The flexibility and durability of foldable device is determined by the weakest link, which happen to be the irreplaceable copper traces within the flexible PCBs.
Solution: Durable Flexible PCBs that Stretch in Every Direction
Interestingly, Samsung filed another patent last month for a radical new flexible PCB design that could significantly improve the toughness and durability of these components. Traditional flexible PCBs are designed to bend along one axis of rotation, but this patent details a new flexible PCB design that allows it to be bent and even twisted along any axis.
Samsung’s latest PCB draws inspiration from the humble telephone cord. If you were born before the turn of the millennium, chances are you’ll have noticed the coiled cord connecting the receiver to the base unit of a traditional landline phone. A coiled cord allows the copper telephone wire to bend and stretch with impunity. Samsung’s flexible PCB patent embraces the same design element.
The conductive traces within Samsung’s flexible PCB design involve S-shaped zig-zag patterns mimicking the coil of the telephone cord. Combined with a traditional flexible substrate that can already stretch in any direction, you have copper traces that have enough slack to uncoil and stretch out to compensate for the tensile and compressive forces generated by the folding and unfolding of a flexible display. This genius design element can make flexible PCBs significantly more durable and less prone to delamination.
Flaw #3: Ingress of Dust and Foreign Particles
Apart from the theories involving faulty hinge and PCB design generating debris that pierced the flexible displays of many of the early Galaxy Fold review units from within, ingress of dust and other foreign particles is another possible cause for the broken displays. It doesn’t take a rocket scientist to figure out that the lack of dust protection in a device with a fragile display and complicated hinge bearing many moving parts is a major oversight.
Furthermore, many earlier reviewers also inadvertently destroyed their displays by peeling off the protective film on top. This was an honest mistake since most new smartphones ship with displays bearing protective films that are expected to be taken off prior to usage. It’s quite evident that the Galaxy Fold’s display lacks structural rigidity and therefore needs another external protective layer to maintain durability.
Solution: Waterproof Flexible Smartphones
This is quite honestly a no brainer. It is imperative for a future redesign to seal off the Galaxy Fold chassis, especially when Samsung has learned the hard way that foreign particle buildup within the foldable hinge mechanism can damage the flexible display. Samsung filed a patent last week detailing “foldable display devices” bearing “encapsulation layers” that can prevent the ingress of moisture.
The patent, however, doesn’t go into the specifics of how it makes the foldable device waterproof, since the concept isn’t limited to a single foldable device. The document instead lists various combinations of inorganic and organic materials (mainly plastics and elastomers) that could be used to seal up the flexible display as well as the entire foldable unit.
Although Samsung hasn’t detailed a specific means to achieve waterproofing for a specific device in the patent, there’s no doubt that the company is hard at work trying to come up with waterproof flexible devices. Combined with a better hinge as well as more flexible PCB design, these three patents are a sign that Samsung is, at the very least, committed to making foldable devices viable in the wake of the Galaxy Fold embarrassment.
It must be noted that the process of research and development is long and takes over a span of several years. All of these patents have also been in the process of evaluation for an equal amount of time. For all intents and purposes, the improvements to foldable phone technology detailed in these patents will most likely in future versions of Samsung’s foldable devices.