Examining an environmental antonym: Tile’s Slim

Within my mid-2021 teardown of Tile’s Mate tracker, I admitted:

I periodically go through bouts of misplacing my keys. And my wallet. Sometimes at the same time.

That forgetfulness prevalence, as you later learned, among other things has encompassed dropping the keys in the driveway, for their eventual digestion (and subsequent disgorgement) by a snowblower. But I digress. I’d bought the 2020-version Tile Mate late that same year (2020), accompanied by a same-model-year Tile Slim for my wallet:

The Tile Slim, unlike its thicker Mate sibling, doesn’t have a user-replaceable battery, for non-coincidental svelteness reasons. Tile claims 3 years average operating life before the device needs to be replaced, and mine lasted a few months more than that; its Bluetooth beacon beamed its final signal last month (as I write these words in late April) wherein I replaced it with a 2022-model successor:

The two versions look near-identical, aside from an imprinted QR code on the back of the newer variant which assists in tracking down the owner if someone else finds it:

More generally, here’s how the three Slim versions compare per company documentation (which has typos I’ve corrected in the following table), beginning with the original 2016 edition:

A few comparative comments before continuing:

• Presumably, since the Slim line was intended from the beginning to be the same wallet-friendly thickness as a couple of credit cards, Tile decided to expand the length of the 2020 and 2022 models to full credit card size, too, thereby enabling larger internal batteries and consequent longer battery life before required device replacement.
• The Tile-documented slight dimensional differences between the 2020 and 2022 models are, I suspect, “rounding errors”; the two models seem visually identical to me.
• All three models are capable of tolerating 3 ft/1 m immersion in water for up to 30 minutes (per the last digit “7” in the IP rating). However, whereas 2016 and 2022 models also document accompanying dust tolerances (respectively “5” and “6”), the 2020 model takes an “X” seeming pass on this particular certification spec, for unknown reasons.
• I can’t find a dB rating for the transducer in the 2022 model; Tile only trumpets that it’s “Louder” (than what?). But I’m betting that it’s comparable to the 2020 version’s 108 dB.
• Tile’s claimed 50 m longer maximum Bluetooth transmission and reception range for the 2022 model, part of the company’s rationalization for its $5-higher price tag versus the 2020 precursor, isn’t seemingly born out by reviews I’ve seen.

One other note on battery life before proceeding with the teardown. Often, even with devices that come with user-replaceable batteries, I find a slim piece of paper or plastic that needs to be removed (thereby completing the circuit between one of the battery terminals and the device’s electronics) prior to as-needed setup and subsequent operation. The Tile Slim doesn’t offer any sort of similar physical barrier, which is understandable given its fully sealed nature, but problematic from warehouse and retail shelf-life standpoints. Instead, you press the front button, whereupon the device emits a little ditty and first-time setup can then proceed.

Presumably, therefore, there’s a non-zero constant current draw from the battery while the device is sitting in the box, unless that initial button press also “makes” an in-parallel permanent connection within the switch between the battery and the bulk of device circuitry (thoughts, readers?). Again, an out-of-box partially-to-fully drained battery is not so problematic with something based on a user-replaceable battery, but in this case a Tile customer would likely be unhappy if they were to buy a usable life-compromised Slim that’d previously been sitting in the store for a long time. And given that the majority of Tile’s 2022 devices (save for the Pro) have non-user-replaceable batteries, the likely potential for consumer uproar is all the more.

Enough with the prep, let’s get to tearing down. Given that the Tile Slim packaging is long gone, I’ll instead dive right in with some overview shots from various perspectives, accompanied by a 0.75″ (19.1 mm) diameter, 1.52 mm thick U.S. penny for size comparison purposes:

See the interstitial seam in that last shot? I bet you know what comes next:

Pop the seam apart, peel away some glue, and the back panel comes right off:

Flip back a metal flap, and the battery also appears:

At this point, the PCB-plus-battery assembly lifts right out, too:

In the upper right is the piezoelectric transducer (aka “speaker”) whose silver- and gold-colored regions press-mate to contacts coming from the PCB. Below it is the inside of the front panel button, which when depressed will presumably press down on a PCB-mounted switch (note the “dimple”; we haven’t yet seen the switch itself, so hold that thought). Here’s a closeup of both:

And zooming back out…so what’s with that metal shield surrounding the battery?

My guess is that it serves dual purposes. Since the Tile Slim is intended for use in a wallet, which might be in the owner’s pocket, it reinforces the battery integrity should the Tile Slim become cracked (would that be a butt crack? Sorry-not-really…) due to environmental stress. And were the battery’s integrity to be compromised anyway, it helps shield the owner’s body (or purse contents, etc.) from being exposed to the resultant “brief-but-intense burst of heat, puff of smoke, and acrid stench”. There may also be a Faraday cage angle, given that we are talking about a RF (Bluetooth, to be exact)-based product here, but the lack of any sort of electrical ground between it and the rest of the system leaves me skeptical. Readers?

Before going further, I decided to re-place the PCB (with its other side, containing the aforementioned switch and transducer contacts, among other interesting bits, now visible) back in the case’s bottom half absent the metal shield so you can see how it’s oriented:

And now let’s take the PCB-plus-battery back out and give it a closer look, beginning with the just-seen front side:

Zooming in on the PCB itself:

Note again the previously mentioned switch and transducer contacts. Note too that the areas containing test point contacts are shinier than the rest (again, hold that thought). And finally, note the “ANT2” mark along the left side. Flipping the PCB over…

And zooming in…

The PCB-embedded antenna (i.e., ANT2…although I can’t find an ANT1 reference; can you?) is obvious. Notice how much blurrier the PCB markings (along with the various components themselves, with the notable exception of the antenna) are on this side? And notice the square-border translucent piece on top of the largest IC? At this point, I’ll let you in on the surprise (which at least some of you probably already figured out). Not only is the battery bendable (for likely already-obvious reasons, given the already-noted dominant use case):

So too is the PCB itself:

What we’ve essentially got here, aside from the flex-PCB and non-coin-battery variances, is a clone of the hardware design found in the 2020-model Tile Mate I tore down three years ago, whose front and back PCB closeups I’ll again show for easy-comparison purposes:

The main system chip underneath the square protective border this time is once again Nordic Semiconductor’s nRF52810 Bluetooth 5.2/BLE control SoC, based on an Arm Cortex-M4. And although I can’t discern the other primary chip’s identity from the flex PCB’s murky translucency, I’d be willing to bet that it’s once again Micro Analog Systems Oy’s MAS6240 piezo driver IC.

In closing, the 2020-model Tile Mate’s FCC ID is 2ABXLT7001, for anyone who’d like to delve further into it in an absolute sense and/or relative to its Tile Mate sibling (FCC ID: 2ABXLT9001) and/or 2022-model Tile Mate successor (FCC ID: 2ABXLT1601S). And with that, I’ll await readers’ thoughts 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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