Cracking the case of a smartphone and its unfairly crack-accused case

By the time you read this, you likely will have already seen my upcoming coverage of Google’s August product announcement event in a bit more than a week (as I write this), where the Pixel 9 series is forecasted to be introduced. However, as regular readers may recall, I’m still toting two Pixel 7s as my smartphone “daily drivers”, along with a Pixel 6a as my “vice-phone”:

following a longstanding just-in-case spare strategy that as you’ll soon see finally came in handy!

Smartphones’ usage patterns make them particularly prone to being dropped, whether its onto hard surfaces or into fluids (such as…err…what’s in a toilet bowl). Mechanical robustness is therefore critical to long operating life, a particularly important requirement considering their stored-data and app importance to their owners coupled with their high prices. All of which has made their dependence on glass materials a longstanding necessity curiosity to me.

The screen’s an obvious one you really can’t avoid, at least until smart glasses go mainstream someday (theoretically), thereby obviating smartphones’ existence rationale. Instead, smartphone designers are stuck with relying on structurally reinforced glass compounds, such as Corning’s Gorilla Glass series, that claim to minimize the chances of a crack. Per Wikipedia:

Gorilla Glass…is a brand of chemically strengthened glass now in its ninth generation. Designed to be thin, light, and damage-resistant, its surface strength and crack-resistance are achieved through immersion in a hot potassium-salt ion-exchange bath.

But glass smartphone backs have always been a bit bizarre to me, no matter that I grok their conceptual benefits, both absolute and relative to alternative materials. Corning this time:

As leading device manufacturers unveil their latest models, many are making a shift to incorporate more advanced glass into their designs, and not just on the front as a protective cover glass. One place where more glass is appearing is on the back of new mobile consumer electronic devices. This trend is particularly exciting because glass offers benefits that other materials, like plastic and metal, just can’t offer.

With glass on the back as well as the front, the newest smartphones are meeting aesthetic and design milestones, including more elegant form factors. But, they offer additional performance benefits. The superior physical and electromagnetic properties of glass make it particularly well-suited to enable new capabilities device makers are incorporating into their designs.

So what are the benefits of having an all- glass smartphone?

Improved Reception
Glass is ideal for the antenna performance of your phone, unlike aluminum and other materials. Metal materials like aluminum lack radio frequency (RF) transparency, meaning that the antenna embedded in your device has a harder time finding a signal. New all-glass phone designs mean more bars in more locations leading to faster data transmission.
Better Wireless Charging
Today’s newest phones are moving to wireless charging, and for the same reasons listed above, metal can interfere with wireless charging technology. Glass, particularly thin, tough glass like Corning® Gorilla® Glass, is used as an alternative to metal on the back of phones so consumers get a faster charge without plugging in the device to a traditional charger.
New Levels of Customization
Since the backs of phones don’t have the same optical transparency requirements as the front display, glass can provide designers with new possibilities for customization. Corning’s true-color glass ceramics — or Vibrant Gorilla Glass — offers superior scratch resistance compared to plastic and unlocks a full palette of color options with premium quality photo realistic images.

And finally, there are the cameras, whose lenses’ outer elements aren’t typically directly exposed to the outside world. Instead, there’s an intermediary transparent (duh) protective cover that’s most commonly glass-fabricated as well. Here, for example, is the front camera of one of my Pixel 7s; note that I’ve also got a tempered glass screen protector on it:

And here’s the back, for now using a case-less “stock” photo:

Until recently, there was only one camera on the back of smartphones, akin to that on the front. But as the Pixel 7 exemplifies, things have gotten a bit more complicated nowadays. Left to right in the photo, integrated within a common “bar” that juts out from the back panel, you’ll see:

The standard primary lens, with 82° field of view (FoV)
A spectral/flicker sensor, and above it, dual side-by-side autofocus sensors (neither of which are clearly visible in the “stock” image; hold that thought)
An ultrawide lens with 114° FoV
A microphone input, and
The LED flash

The Pixel 7 Pro adds a third 5x telephoto camera, to the right of its now-125° FoV ultrawide lens. And while the Pixel 7a looks similar to the Pixel 7 (albeit with a plastic-vs-glass back), its ultrawide camera is once again focal length-tweaked, this time to deliver a 120° FoV.

The cases I use on both of my Pixel 7s are Limitless models from Mous (Aramid Fibre and Black Leather, to be precise), and although they’re a fair bit more expensive than the no-names on Amazon, they’re pretty slick. For one thing, they’re quite rugged (again, hold that thought):

and they also have Magsafe-compatible magnets built into them:

Further to Mous’s protection claims, if you revisit the earlier photo of the front camera, you’ll notice a “lip” that extends above the screen. That “lip” goes all the way around the front, creating an “air gap” designed to prevent the screen from directly impacting with the ground if the phone lands flat…as long as, for example, the ground isn’t covered by rocks or other objects thick enough to surmount that gap.

What about that rear “camera bar”? Glad you asked. Here’s what both of my Pixel 7s, an “Obsidian” one on AT&T for personal use and a “Snow” one on Verizon for work (which I’ve also included for enhanced color-contrast viewing purposes), look like from an angle when encased:

Again, note the “lip”. Here’s the former, and the specific subject of today’s tale, straight on:

So…what happened? In late June, I happened to glance at the back of my AT&T-enabled Pixel 7 and saw what looked like an impact crater centered on top of the ultrawide camera lens, with cracks emanating from there all the way to the primary camera to its left. I unfortunately only in-retrospect thought that I should have snapped a photo of it (from another camera, obviously), but the damage looked similar to a photo posted by Kyriakos Ktorides on X/Twitter:

My immediate reaction was that I must have dropped it, with a pebble or the like impacting and cracking the cameras’ common glass cover. But after wracking my brains, I couldn’t recall any time that I’d dropped the phone, landing on its back or any other orientation. Theoretically, I suppose I could have popped it with the tip of a same-pocket key, but that also seemed unlikely.

So I hit up Google and was quickly (albeit vaguely) reminded of coverage I’d previously seen on this seemingly fairly widespread issue. Initially, all the reports I came across consistently mentioned the ultrawide camera lens location as the damage origination point, so I thought that perhaps optical zoom lens back-and-forth movement had impacted the glass, iteratively weakening it to the point where it finally fractured. But then I remembered that, with a few exceptions, smartphones’ lenses don’t actually have moveable elements (aside from focus, that is). Instead, they interpolate between the viewpoints of multiple cameras, each with a fixed-focal-length lens, to generate the optical zoom-like effect. Plus, as my research eventually revealed, cracks seen by others didn’t solely originate from the ultrawide camera area, anyway.

I’d also read on Reddit and elsewhere that Google had been telling folks that, in addition to phone-drop artifacts, this cracking might be caused by using the phone in conjunction with temperature-change extremes (cold climes, to be precise). However, we’re talking about mid-summer here, folks. My wife and I had also just returned from a trip, but given that airplane cabins are pressurized, I don’t think that pressure changes were to blame (although we did go between 7,500’ elevation in Colorado and less than 1,000’ in Indiana, so…yeah, no…)

Abundant reporting online suggests that spontaneous cracking independent of mishandling or any environmental or other external factor is the root-cause conclusion in situations such as mine. Thankfully, I ended up being doubly blessed. For one thing, I was relieved to learn that I had less than a month left on my factory warranty (I’d also purchased a third-party extended warranty on the phone, but coverage for situations like this was unknown). And for another, although Google initially balked at covering these particular repairs, instead blaming user mishandling, the company ultimately relented and was doing them for free under warranty.

Two days after filing my claim with Google online on Saturday, June 29, I had a free-overnight-shipping box and FedEx label in my hands. Two days later, on July 3 (the day before the long holiday weekend) Google had already received and inspected my phone, confirming that its necessary repairs were warranty-covered. The following Tuesday, July 9^th, it was back in my hands, courtesy of another one-day FedEx shipment and despite two intermediary weekends and a holiday. As documented, both the front and rear camera modules ended up being replaced in addition to the glass rear camera array cover. It’s seemingly good as new, and while it was away, I pressed my Pixel 6a into service in its stead, backing up the Pixel 7 then restoring the backup to the Pixel 6a beforehand, and reversing the process upon the Pixel 7’s return.

In closing, while the title of this piece refers to “cracking the case”, to date I admittedly remain a bit baffled as to exactly why the rear camera array cover spontaneously shattered. That said, Ars Technica coverage I came across in my research contained an interesting quote:

These specialized smartphone glass panels increase scratch resistance by building stress into the glass. We don’t know the manufacturer of Google’s camera glass, but a Corning engineer explains the general process in this Scientific American article, saying, “There’s a layer of compressive stress, then a layer of central tension, where the glass wants to press out, then another layer of compressive stress.” If you mess something up in your glass formula and these layers aren’t in a perfect balance, one day the glass will just go “pop” and you’ll get these outward mini explosions.

Here’s more background info from the Ars Technica piece:

We’ve seen this exact problem several times before in the world of smartphones. Samsung was hit with this issue in 2016 on the Galaxy S7 and again in 2021 the Galaxy S20, both of which kicked off class-action lawsuits.

Further, the Google situation isn’t restricted to the Pixel 7; user reports suggest that the Pixel 7 Pro and Pixel 7a are similarly afflicted. Nor did the company seemingly fix the problem with the successor Pixel 8 generation of products, either; here’s just one of numerous case study examples of cracking issues (and yes, Google once again seems to be initially balking at owning up to covering the repairs under warranty). Fortunately, my other (Verizon-enabled “Snow”) Pixel 7 hasn’t exhibited the same behavior, at least yet; its factory warranty also expired in mid-July, but its Preferred Care extended warranty coverage is from Google, so hope springs eternal.

Could folks who dropped their phones try to scam Google into repairing them for free, too? Perhaps. Google’s initial reticence is therefore at least somewhat understandable. But quoting a phrase I’ve also used in plenty of prior writeups, where there’s smoke there’s usually fire, and there seems to be a lot of smoke here. I hope Google sorts this situation out for its Pixel 9 and future smartphone families. And if any of you have glass-composition expertise, I’d love to hear your root-cause theories in the comments!

—Brian Dipert is the Editor-in-Chief of the Edge AI and Vision Alliance, and a Senior Analyst at BDTI and Editor-in-Chief of InsideDSP, the company’s online newsletter.

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