The Stealth Winners in iPhone X

　　MADISON, Wis. — You might think the world has already seen enough Apple iPhone X teardowns. But there are grunts in the trenches who just can’t seem to get enough.

　　Certainly, iPhone X teardowns focused on logic ICs have been there, done that. But the untrodden ground Apple has really broken is in areas such as optical modules, components, MEMS, packaging and PCB technologies, according to Romain Fraux, chief technology officer at System Plus Consulting, Yole Développement’s reverse-engineering partner.

　　Last week, EE Times sat down with analysts at both Yole (Lyon, France) and System Plus Consulting (Nante, France).

　　Asked about Apple’s most significant advancement in its iPhone X, Jean-Christophe Eloy, Yole’s CEO and president, nominated “the optical system Apple has brought to mobile devices.” He said Apple’s big milestone is that 3D sensing — an ability to recognize faces much more accurately than any existing Android phone — is now “poised to spread to everything from tablets to cars and door bells.”

　　EE Times asked both Eloy and Fraux to lay out highlights of their discoveries from in-depth teardowns. We also asked them to identify lesser known players who got iPhone X design wins.

　　AT&S, Austria-based PCB manufacturer, wins big

　　The analysts named, among others, AT&S (Leoben, Austria), a European PCB manufacturer, as a significant contributor to the highly integrated iPhone X.

　　While teardown experts such as TechInsights and iFixit alsomarveled at the PCB sandwich they saw in iPhone X, Fraux noted that AT&S, so far, “has been the only one capable of offering such an unprecedented level of high-density interconnect” on PCB boards.

　　By stacking two PCB boards together, Fraux estimates that Apple saved 15 percent of the iPhone X’s floor space. That gave Apple room for extra batteries, he added.

　　There’s no question that modified semi-additive processes (mSAP) and advanced manufacturing techniques are enabling high-density interconnects in smartphones at lower cost and faster production speeds.

　　Yole’s Eloy pointed out the substantial contribution that AT&S’ mSAP technology made to the company’s recent financial results. AT&S last week reported a revenue jump of 24.5 percent to 765.9 million euros in the first three quarters (April 1 to Dec. 31, 2017) compared to the same three quarters in 2016.

　　As Fraux explained, mSAP is “used for manufacturing of laminate or build-up substrates, with a premade dielectric sheet and a thin Cu (copper) layer serving as the seed layer prior to further patterning and Cu plating.” The advantage of mSAP is that a much thinner copper layer coats the laminate and plates areas where the resist isn’t applied. mSAP allows trace geometries to be defined via photolithography. The traces are therefore formed more precisely, maximizing circuit density and enabling accurate impedance control with lower signal loss.

　　Bosch develops custom IMU for Apple

　　Apple’s decision to add an LTE modem in its newest Apple Watch presented a big challenge: the thickness of the watch.

　　Fraux identified Bosch Sensortec (Reutlingen / Kusterdingen, Germany) as the company that stepped up and customized an inertial measurement unit (IMU) for the new watch. Bosch reduced IMU thickness from “0.9mm to 0.6mm,” he noted. “This is the market’s thinnest 6-axis IMU.”

　　This led to Bosch replacing InvenSense inside the newest iPhone 8 and iPhone X, and supplanting STMicroelectronics (Geneva, Switzerland) for the Apple Watch Series 3.

　　These three design wins will give Bosch “hundreds of millions of units in sales per year,” estimated Fraux. This makes Bosch practically “the undisputed leader in MEMS IMU for consumer applications.”

　　In a recent report from System Plus Consulting, Fraux observed, “Bosch Sensortec made significant changes — particularly for the accelerometer, where the old single-mass structure was abandoned for a new structure achieving better sensing properties. The micromachining manufacturing process, unchanged by Bosch Sensortec for many years, was also revised, with a new process for both accelerometer and gyroscope.” He added that “a new ASIC die was designed to fuse the data from the accelerometer and gyroscope, and probably to deliver even lower current consumption and other functionalities.”

　　Broadcom’s advanced SiP for LTE

　　The industry has been obsessed with the battle between Intel and Qualcomm over which will win the modem socket for Apple’s newest iPhones. But we all now know that they move won in iPhone X. In different iPhone X models in different regions, some modem chips will be Intel, some Qualcomm. Ho hum.

　　A less-discussed issue, however, is the RF SiP designed for front-end modules in smartphones. Why does this matter?

　　Noting that 5G communication technology portends “a new order to the market,” System Plus Consulting explained in its own report that packaging could be “a major domain where performance, integration and cost efficiency will be optimized… as all high-quality competitors are looking for a better way to make high-density front-end communication devices.”

　　Fraux highlighted Broadcom/Avago’s advanced RF SiP for the iPhone X. Broadcom developed an unprecedented level of integration — 18 filters close to 30 dies — in its SiP, he explained. Broadcom designed it to accommodate mid and high band in Japan (Band 42, 3.6GHz).

　　This Broadcom module is essential for SIM-free phones. Fraux noted that in iPhone X A1865 & A1902, Broadcom & Skyworks supply the front-end modules (FEM). In iPhone X A1901, Broadcom, Skyworks & Epcos are the FEM suppliers.

　　Breakthrough optical system in mobile

　　When all is said and done, Yole’s Eloy sees iPhone X’s optical system as its genuine advancement. The iPhone X’s TrueDepth camera is enabled by a “complex assembly of five sub-modules” embedded in Apple’s optical hub, as EE Times previously reported.

　　The sub-modules are a near-infrared camera supplied by ST, a proximity detector (time-of-flight) + IR flood illuminator by ST, an RGB camera, a dot-pattern illuminator provided by Ams (Unterpremst?tten, Austria), and a color/ambient light sensor developed by Ams. The RGB camera sensor is a product of a “complex supply chain,” observed Fraux, as “Sony provides the CIS, while LG Innotek probably supplies the module.”

　　The key to the system is that the IR camera, RGB camera, and dot projector are aligned and designed to work together.

　　As Pierre Cambou, activity leader for imaging and sensors at Yole Développement, previously explained to EE Times, to have a 3D camera on the front of the iPhone X to identify its owner’s face and unlock the phone, Apple combined a ToF proximity detector with an infrared “structured light” camera that uses either uniform “flood” or “dot-pattern” illumination.

　　The way the 3D system works is very different from a regular CMOS imager taking a photo, he noted. First, the iPhone X combines an infrared camera with a flood illuminator that projects uniform infrared light. It then takes images, which, in turn, trigger a face-detection algorithm.

　　This face-recognition function, however, isn’t meant to run all the time. The infrared camera linked to the ToF proximity sensor tells the camera to take a picture when it detects a face. The iPhone X then activates its dot-pattern projector to take an image. Both regular and dot-pattern images then go to the application processing unit (APU), which puts them through a neural network trained to recognize the owner and unlock the phone.

　　Fraux noted that in ST's proximity sensor and flood illuminator module, ST is using its own VCSEL (vertical-cavity surface-emitting laser).

　　Pointing out the five sub-modules lined up at the top of iPhone X, Fraux noted that when Apple considers reducing the size of the iPhone, innovation must come from potential miniaturization or integration of those sub-modules.

　　Mystery of one less microphones

　　In both iPhone 7 and iPhone 8, Apple used four microphones per handset. They include three front-facing microphones, one on top and two on the bottom, and a rear-facing top microphone.

　　Fraux explained the front-facing mic cancels noise, the one in the rear records, and the two bottom mics are for speech.

　　Instead of those four microphones, System Plus Consulting found only three in iPhone X. Apple has only one mic at the bottom of the handset, Fraux revealed. Asked why, he told us that he hasn’t solved that mystery yet.

　　The three mics inside iPhone X are dual sourced to Goertek (China) and Knowles (Itasca, Ill.) , according to Fraux.