TOKYO -- On the outside, Apple's latest iPhone models, the 5s and the 5c, are not much different from the iPhone 5. Yes, there is fingerprint recognition on the 5s, and the 5c comes in bright colors, but that is pretty much it. On the inside, it is a whole other story.
The Nikkei Electronics magazine, with the help of an outside engineer, recently did teardowns of the 5s and 5c to see how these models differ from their predecessor. What we found gives us a glimpse into Apple's technical strategy and relations with its suppliers.
More packed in
First, there is the brain of the smartphone. For the 5s and 5c, this is the newly developed A7 application processor. A DRAM package sits on top of the processor package just like in other iPhones, but internally there are major changes from the A6 processor of the 5.
Inside the A7 package is a chip measuring 10.47 x 9.83mm. When examined with a metallurgical microscope, the chip's elements and structure matched those of Samsung Electronics' next-generation Exynos 5410 processor, which is made with a 28nm circuit-drawing process. The conclusion of our guest engineer was that the A7 is made by Samsung using its 28nm processing technology.
Samsung also made the A6 processor for the iPhone 5. That chip was fabricated using a 32nm process. And though the A7 uses a 28nm process, it has a larger footprint than the A6 -- around 6.4% more.
When the wiring layer was peeled back to expose the circuit blocks that comprise the chip, the gaps between circuit blocks, which are readily apparent in the A6, are much narrower in the A7. With the combination of a larger footprint and a finer process, the engineer concluded that the A7 is effectively several tens of percent larger in circuit scale than the A6.
The appearance of the CPU portion of the A7 is also different than the A6. For the A6, Apple employed a design method where the positions of functional elements were determined by hand and could be visually distinguished. On the A7's central processor, the functional elements cannot be distinguished. This harkens back to the appearances the central processors of chips through the A5, which were designed through automation.
Given enough time, experienced engineers can manually design chips with extremely small footprints operating at high clock speeds. But automated design is an easy way to shave off design hours, and the engineer speculated that Apple may have opted for this method so as to give priority to innovative logical structures for the 64-bit execution mode.
The teardowns continued with a look at the new M7 co-processor in the 5s. The M7 keeps track of the state of the handset by collecting data from the gyroscope, accelerometer and electromagnetic compass. Based on the markings on the die, it appears that the M7 is made by NXP Semiconductors and is part of the Dutch company's LPC1800 series of microprocessors.
The various chips and modules in both the 5s and 5c are printed with serial numbers -- such as 338S1216 and 338S1201 -- that adhere to Apple's naming rules. But taking them out of their packages and looking at the markings on the dies reveal the actual makers. It appears that Apple has continued to work with the same suppliers that make these parts for the iPhone 5. For example, the power management IC chip is made by Dialog Semiconductor, and the audio codec is made by Cirrus Logic.
The displays of the 5s and 5c are also a carryover from the 5. With the help of Touch Panel Laboratories, evidence was found suggesting that both of the new models adopt the same in-cell touchscreen technology as the 5, where the touch-sensing elements are integrated into the liquid-crystal display.
When Apple debuted the iPhone 5, these in-cell touchscreens had poor yields. The fact that the company decided to continue to use this technology for the 5s and 5c suggests that the yields have since improved.