Teardown: Apple iPhone X

It is just over a year since Apple stirred things up by dropping the 3.5mm headphone jack. The iPhone X goes much further, although its launch has proved less controversial.

The difference is that the X represents a major design overhaul, one many Apple followers feel is overdue. It arrives with a premium price – $999 in the US and £999 in the UK – and it is a transformative product. Many new features either follow market trends (an all-screen front, Apple’s first OLED display, wireless charging) or are likely to extend across the iPhone range over time (Face ID security, Animojis).

The X shares important specifications with the iPhone 8 and 8 Plus, also launched in 2017. Most notable is the A11 ‘Bionic’ applications processor. However, with the X more specifically tailored for augmented reality (AR) and demands for greater camera performance, it better showcases what Apple’s latest silicon can do.

Major features of the A11 are a 64-bit six-core configuration (two 2.39GHz high performance ARM-based Monsoon cores, alongside four power-optimised Mistral cores), neural network hardware targeting AR and machine learning with 600bn operations-per-second capacity, and an in-house designed three-core graphics processor (the first since Apple’s break with Imagination Technologies’ PowerVR core).

Apple says the Monsoon cores are 25 per cent faster than the equivalents in the A10 and the Mistral cores are 70 per cent faster. It is manufactured on a 10nm TSMC process.

As with the 8 Plus, Apple has increased the Ram capability, stacking the A11 package-on-package with 3Gb of LPDDR4x standard memory.

According to an iFixit teardown, Apple has taken some atypical design decisions in order to fit the X’s features inside a phone that is smaller than the 8 Plus (144 x 71mm vs 158.4 x 78.1mm and 174g vs 202g) yet has a larger screen (5.8in vs 5.5in diagonal).

In addition to space saved by dropping the ‘Home’ button, the designers have gone for high component density on stacked logic boards. Two main boards are in a sandwich with a third spacer PCB lining the perimeter. Data transfer is through vias rather than wires.

The board’s footprint is 70 per cent of that in the 8 Plus, but component density is 135 per cent. Despite that, the X is only marginally thicker than the 8 Plus (7.7mm vs 7.5mm).

Apple has then looked to achieve more area flexibility inside the X by choosing a two-cell battery.

While its combined 10.35Wh (2716mAh at 3.81V) capacity is ahead of the 10.28Wh battery in the 8 Plus, iFixit notes that it is still some way behind the 12.71Wh for the Galaxy Note8. Rather, the goal has been the creation of space for features such as the 7MP Face ID/Selfie camera array, and adopting a vertical rather than horizontal configuration for the main 12MP two-camera array.

On that last decision, Apple says the vertical set-up delivers better results for AR as most apps are optimised for landscape mode. Apple aims to raise the bar in other ways with its main camera, incorporating a number of features and options allowing owners to take more ‘professional’ photographs. However, it is the Face ID array that has attracted most attention.

No home button means no fingerprint sensor. Instead, the X uses facial recognition. The PCB for the Face ID technology incorporates three components, in addition to a flood illuminator embedded in the display.

IFixit explains how they work: “The flood illuminator blasts your face with infrared (IR) light. Next, the front-facing camera confirms the presence of a face. Then an IR dot projector projects a grid of dots over your face to create a three-dimensional map. Finally, an IR camera reads this map, and sends the data to the phone.”

The results are processed using technology developed by Israeli company PrimeSense. It provided the depth and motion image analysis inside Microsoft’s original Kinect Xbox peripheral. Face ID represents the latest generation of PrimeSense’s wares since its $360m acquisition in 2013.

Apart from all the clever stuff involved, the big question is whether Face ID represents a major improvement in security, particularly given increasing use of phones to make payments.

The first hackers to publicly claim to have spoofed the system, respected Vietnamese group Bkav, had to go to some lengths to do so. It needed sufficient visual data about the user to create a mask using 3D printing that could fool Face ID.

While this is a vulnerability, it is probably beyond the effort a criminal would consider worthwhile to exploit a typical user. It will be of greater concern to those who approve phones for use by individuals in sensitive government or corporate positions.

After Face ID, the other big concern with the X has been the home-button’s disappearance and replacement by gestures in this implementation of iOS 11. Some reviewers have found it hard to get used to the new commands and suggested that Apple could, as on the Android OS, have offered a virtual home button while the market got used to the all-screen format.

As said at the outset, the X is an attempt to advance the iPhone, integrating features that are serving rivals well with some of Apple’s own magic.

As such, seasoned early adopters probably will not be surprised they are being expected to adapt, and that a few details still need to be refined (though the techno-bling brigade may be more whiny).

The real challenge will lie in bringing the X’s interesting ideas to the wider market. Apple has never been ‘cheap’ but even it acknowledges that £999 for a phone is the upper limit.

Key components: Apple iPhone X

Exploded view

1  Cabling
2  PCB for loudspeaker, microphone, ambient light sensor, flood illuminator and proximity sensor
3  Logic board 1
4  Logic board 2
5  Front/Face ID camera array
6  Wireless charging coil
7  Cabling
8  Lightning port cable
9  Logic board 3
10  Rear 12MP camera
11  Flash
12  Taptic engine
13  Barometric vent
14  Lower speaker
15  SIM tray
16  Front/display
17  Battery
18  Cabling
19  Rear enclosure

Logic board (1)

20  Power management, Apple
21  Apps processor, Apple
22  Battery charger, Texas Instruments
23  Audio codec, Apple
24  Power management, Apple

Logic board (2)

25  Power amplifier, Skyworks
26  Gigabit LTE transceiver, Qualcomm
27  Wi-Fi/Bluetooth module, Apple/Murata
28  LTE Modem, Qualcomm
29  Power management, Qualcomm
30  NFC controller, NXP Semiconductors
31  Power amplifier, Skyworks
32  Power amplifier, Skyworks
33  MMMB power amplifer, Broadcom/Avago
34  Power amplifier, Skyworks

Face ID array

35  IR camera
36  Front-facing camera
37  IR dot projector