Why Glass is Replacing Aluminium and Plastic in Flagship Smartphones, and Why it Shouldn’t

Smartphone design trends come and go, but one trend which has been persistent for the past few years has been the transition to premium materials used in the construction of smartphones. While there was a time when it seemed like every single Android phone was made of plastic, design paradigms have slowly but steadily changed since 2013.

HTC was the OEM which pioneered aluminium unibody phones back in 2010 with the HTC Legend, and then innovated again with discrete antenna brands on the One M7 released in 2013. However, for much of 2013 and 2014, it seemed HTC and a few Chinese OEMs were the only ones taking smartphone build materials seriously. This was because the elephant in the room of the Android world – Samsung – still opted to stubbornly keep the polycarbonate design in its flagship Galaxy S and Galaxy Note series of smartphones, up until they began flirting with metal through the Galaxy Note 4 and Galaxy Alpha.

The turning point came with the release of the Galaxy S5 in 2014, which was heavily criticized for yet again having an all-plastic construction (made worse by the "Band-Aid" look and feel). The Galaxy S5 failed to sell as well as its predecessors, and a lot of blame for that was put on the design internally in the company. To rectify that, Samsung started over with Project Zero, which eventually became the Galaxy S6 when it released in April 2015.

Although Apple had started to move away from glass with the iPhone 5 (which featured a unibody aluminium body combined with glass cutouts at the top and bottom) and went on to completely move away from it with the iPhone 6 in 2014 (full aluminium unibody with discrete antenna bands), Samsung opted to release a metal-and-glass sandwich design with the Galaxy S6 and the S6 Edge. Unlike Apple, Samsung used aluminium instead of stainless steel for the frame.

Samsung might not have predicted it at the time, but the basic feature of that design – an aluminium-and-glass sandwich – is what most flagship smartphones today are trying to emulate and perfect.

Those smartphone OEMs which had been making plastic phones switched to metal-and-glass phones. The ones which had been making plastic phones for the budget smartphone market switched to making phones with aluminium backs and plastic frames, and then even switched to full unibody aluminium construction. Finally, the smartphone OEMs who had been making smartphones with full aluminium unibodies are switching to the metal-and-glass sandwich design.

The state of smartphone design

These sweeping changes have made it increasingly harder (though certainly possible) to find a unibody metal Android flagship smartphone, and it is nearly impossible to find a flagship Android smartphone made of plastic. While the death of plastic in smartphone construction is something we won't miss too much (especially the cheap, glossy plastic used by Samsung and LG in the past), the slow and looming death of unibody aluminium construction is a real cause for concern as this industry-wide shift occurs.

Samsung, for example, still uses an aluminium frame with the Galaxy S8, S8+ and the Note 8, but the aluminium frame has been polished to look and feel like glass (most apparent in the "Orchid Gray" models). It doesn't even have the traditional sand-blasted aluminium coating any more.

Apple began moving away from aluminium with the Jet Black version of the iPhone 7, which looked and felt like glass. With the iPhone 8 and the iPhone X, the company has stopped making aluminium unibody phones in favour of the metal-and-glass sandwich design. The iPhone 8 uses a series 7000 aluminium frame, while the iPhone X uses a stainless steel band, reminiscent of the iPhone 4.

In the Android world, the pioneer of aluminium unibody smartphones itself released a metal-and-glass sandwich as its flagship smartphone for 2017. While the HTC 10 was the quintessential HTC phone with an all-metal build and tank-like build quality, the HTC U11 represents the end of an era as there is no unibody metal (ingot) construction; instead, 3D glass is used in conjunction with an aluminium frame. Except for a few OEMs such as OnePlus with the OnePlus 5, HMD Global with the Nokia 8, Motorola with the Moto Z2 Force and Google with the Pixel 2, few major international OEMs have an aluminium unibody flagship phone to sell.

Why are manufacturers moving from metal to glass?

Why are OEMs switching to glass backs? There are a few reasons for that. Firstly, according to them it makes the back of the phone "look more premium." Secondly, it's easier to engineer the radio interfaces through glass than through metal. Thirdly, imitation is the name of the game in the smartphone industry, as manufacturers tend to follow successful design philosophies. In this case, Samsung knocked it out of the park with the designs of the Galaxy S6, S7 and S8, so it's being imitated.

However, is this trend a positive one, or a negative one? The correct answer for that, of course, is that it depends on personal preference, but that's not all there is to it. Overwhelming demand for phones with glass backs such as the Galaxy S8 and the Galaxy Note 8 as well as the upcoming iPhone X seem to prove that consumers are fine with glass backs.

However, there are objective reasons why one type of build construction (in this case, unibody metal) is superior to another type of smartphone build construction (metal-and-glass sandwich). Let's look at these arguments one-by-one:

Why pay more for flagships, when budget and mid-range phones now have aluminium unibody construction?

Phones like the Xiaomi Mi A1, Xiaomi Mi Max 2, Moto G5S Plus and others now have full metal unibody construction, which means that, in many cases, they have better structural rigidity than glass-backed phones. Their fit and finish is impeccable, to the point where you can't tell a phone's price on the basis of its design alone. For example, the Mi A1 looks and feels strikingly similar to the OnePlus 5 (and, in turn, the iPhone), which costs more than two times as much as the Mi A1.

A few years back, consumers felt compelled to move up to flagship smartphones because of the improvements in build quality over budget and mid-range smartphones. Although 18:9 aspect ratio displays with smaller bezels and curved screens with rounded corners are fulfilling the role which at one time build quality used to fulfill (as adoption of this design feature is slow in the lower price segments), it is still more difficult to make the case for moving up on the basis of design alone.

Metal as a heat sink

We have seen it time and time again: metal unibody smartphones can perform better than smartphones which have glass backs during sustained usage. Glass backs are not heat conductors. They trap the heat inside, forcing the processor to throttle. On the other hand, a metal unibody allows for better heat dissipation and may allow the processor to run at high clock speeds for a longer period of time For example, the OnePlus 3 posted fantastic results in the performance over time section of its XDA review (prior to benchmark cheating), outclassing their glass-backed competitors using the same chipset.

Throttling has a very real impact on device responsiveness during prolonged sessions, and while the latest SoCs are focusing on sustained performance, there still remains a long way to go. While we focus on achieving the long-term goal, it's important to have the right tools for the job, and in this case, that can mean just having a metal unibody construction. In specific usage scenarios like gaming, metal phones have an inherent (albeit not necessarily enormous) advantage that can lead to better performance over time.

Scratch resistance of Gorilla Glass is still not good enough

With each new generation, Corning promotes the improved scratch resistance of Gorilla Glass. While Gorilla Glass is effective for display protection, it doesn't do such a great job when it comes to protecting the back of the phone (especially given how phones are normally laid down). The bulk of the improvements we saw in Gorilla Glass 4 and 5 were focused on shock resistance instead of scratch resistance as well.

Suggested Reading: Gorilla Glass 5 and Shattered Expectations: Revisiting Old Solutions to Current Problems

At the end of the day, Gorilla Glass is still glass and glass will scratch to the point where microscratches will be visible after wear-and-tear. The scratch resistance of Gorilla Glass won't match the intrinsic properties of aluminium, and aluminium phones tend to be very hard to scratch as long as the coating used is of a high-quality variety.

The collection of fingerprints on glass backs

While the front glass of phones such as the Galaxy S8 is relatively free from fingerprints, the back glass is a mess of fingerprints that will have to be cleaned frequently in order to keep the phone looking pristine.

On the other hand, aluminium unibody phones don't have a problem of fingerprints. Black-coloured aluminium phones did have a problem with the cleaning of fingerprints, but this year we are seeing unibody devices launch with smudge-resistant coatings which do work well quite well.

The major problem: shatter resistance

To put it simply, aluminium will not break after a drop — in the worst of cases, it will dent leaving an inconvenient mark (that will forever remind you to be a bit more careful with your purchase). Glass, on the other hand, has a high chance of shattering. You can improve shatter resistance, but you cannot fix the problem entirely. You can reduce the chances of a catastrophic breakage of glass, but you cannot eliminate the possibility of it happening. Phones like the Galaxy S8, G6 and the U11 have been said to be some of the most fragile devices ever — they might pass bend tests, but they don't fare quite as well upon drops.

High repair costs make an accidental smartphone drop a nightmare

Accidental damage is not covered under warranty. In India and other developing countries this is especially troublesome as you have to send the phone for repair and pay the repair costs yourself. As these repair costs are outrageously high, what was an accidental drop turns out to be a nightmare. There have been many cases where buying a brand new lower mid-range phone is cheaper than repairing a flagship phone.

Also, service centers of most OEMs provide laughable service in India. It's so bad that customers have shared all over the Web horror stories of experiences at official service centers. The problem isn't with the quantity of the service centers, but rather the quality of service provided. Imagine cracking your glass-backed smartphone and waiting for up to one month to get it repaired. But this happens in India. It happens, sadly, with a depressing regularity.

The "use a case" argument is null and void

When proponents of glass backs on smartphones are presented with the above arguments, they have a simple answer: "Just use a case." However, just using a case doesn't solve the intrinsic issues of glass backs.

Firstly, official cases are expensive in India and many third world countries, where counterfeit cases from "popular" brands are also common. Apple, Google, and others are guilty of selling cases at inflated prices compared to the official Western prices, and import tariffs make many alternatives nonviable. They can blame currency conversion rates all they like, but the consumer doesn't care about that in the end. The consumer only sees that these companies have hiked up their accessory prices, to the point where they are launching a case at $60 when you can get, say, the Xiaomi Redmi 4 brand new for $110.

Using a case should never be essential; instead, it should be optional to provide an additional layer of protection. With glass backs, cases are more of a necessity if you want to protect your $1000 flagship phone.

Aluminium vs. Plastic vs. Glass

The glass back is a textbook example of form being chosen over function; it may look good, it may look flashy, but it comes with real compromises. Considering the increasing fragility of 2017's full-screen devices as we move closer towards a bezel-less future, it would be a better decision to go unibody and minimise the risk of damage. The stronger the construction, the less likely damage will occur, and the less likely users will have to suffer headaches, especially in much of the developing world.

What do you think of this paradigm shift towards glass backs in flagships? Do you prefer it to metal unibody or polycarbonate designs?

Source: Why Glass is Replacing Aluminium and Plastic in Flagship Smartphones, and Why it Shouldn't