Whenever Apple Inc. releases a new iPhone, teardown analysis firms like IHS Inc., UBM and iFixit quickly dissect it and highlight the big-ticket components inside, such as the display, the processor, the battery and the memory chips. However, like all electronic products, the iPhone also contains smaller devices that are essential ingredients of the design—including capacitors.
The IHS teardown of the iPhone 6 illustrates the critical role that capacitors play in such marquee electronic products, with an estimated 730 of these passives found in the smartphone. Capacitors are present in every major subsystem of the iPhone 6, illustrating just how ubiquitous these devices are.
BOMs Away
In a preliminary teardown analysis conducted in September 2014, IHS estimated that the bill of materials (BOM) of the iPhone 6 equipped with 16 gigabytes (GByte) of NAND flash memory totaled $196.10.
Indeed, the big ticket items with cutting-edge technology account for the majority of the cost.
For example, the iPhone 6’s display subsystem uses Apple’s high-definition Retina technology, and advanced in-touch, in-plane switching LCDs. The applications processor is Apple’s A8, which was cutting-edge at the time, manufactured using an avant-garde 20 nanometer semiconductor manufacturing technology and including twice as many transistors as the previous-generation A7.
IHS didn’t reveal per-part pricing for these major components, but the display and applications processor subsystems in the iPhone 6 cost $45.00 and $20.00 respectively.
Capacitors’ Claim to Fame
In contrast, all but one of the capacitors in the iPhone 6 cost fractions of a cent per device. When added together, the 730 capacitors in the smartphone cost just $2.13, representing only 1 percent of the total BOM.
However, the capacitors permeate every portion of the design, from the main printed circuit board (PCB), to the input/output and interface PCB, to the home button PCB, to the front microphone PCB, to the display module, to the camera flash/sleep/wake button PCB.
All but one of the capacitors in the product is a multilayer ceramic (MLCC) device. This reflects the MLCC’s status as the most common capacitor found in electronic devices, with an estimated 1 trillion of these devices used every year. IHS identified the MLCCs as being either X5R/X7R capacitors, C0G/NP0 devices or feedthrough parts. The NPO, X5R and X7R monikers define the dielectric and temperature range and permitted capacitance charge.
Feedthrough ceramic capacitors engage in bypass purposes. They come in a tube shape, with inner metallization contacted with a lead and outer metallization for soldering. The one standout part was a tantalum encapsulated device from Rohm Co. Ltd. This device, the most expensive capacitor in the iPhone 6, was priced at about $0.02. Tantalum capacitors are employed in sample and hold circuits and power supply filtering on computer motherboards and cell phones. The Rohm tantalum capacitor is used on the iPhone 6’s main PCB.
Capacitors Across the Board
Capacitors in the iPhone 6 are found throughout the various subsystems of the smartphone.
The main PCB of the phone contains the central functionality of the iPhone 6, including the A8 processor, the DRAM, the wireless modem and the gyroscope and accelerometer sensors. Because it incorporates all these key system functions, the main PCB also contains the largest number of capacitors of any subsystem of the smartphone by far, with 682 devices.
The next largest number of capacitors is found in the I/O and interface PCB, with 17 devices. The display/touchscreen module is next with 11 capacitors. This is followed by the home button at nine, the front microphone PCB at seven, and the camera flash/sleep/wake button PCB at four.
Apple Efficiency
The large number of capacitors in the iPhone 6 is all the more remarkable when considering Apple’s highly integrated and efficient approach to mobile electronics design. Apple’s mobile products are renowned for concentrating their functionality into large integrated circuits, which minimizes the usage of smaller components, such as discretes and passives.
The secret of Apple’s elegant design is its tight control over the design, software and component selection for its products. While Apple produces its own operating system (OS), other mobile device makers use OSes from third-party firms. Apple also develops its own blueprints, while other companies frequently employ reference designs that employ third-party reference designs from contract manufacturers and semiconductor suppliers. The company also conducts its own design of its key processing integrated circuit.
This approach allows Apple to achieve design efficiencies on mobile devices that other tablet manufacturers cannot attain. These efficiencies are manifested in areas like memory density, battery usage, cost, space savings, performance and component count, according to IHS.
The less integrated approach used by other manufacturers means that even more capacitors can be found in their smartphones compared to the Apple products.
Capacitor Outlook
While Apple is a major player in the smartphone market, products based on the company’s iOS operating system are expected to account for less than 17 percent of worldwide unit shipments in 2015, according to the market research firm IDC. The vast majority of the remaining shipments will be accounted for by Android. This means that an overwhelming number of smartphones shipped every year use designs with more discrete and passive components than are found in the iPhone line.
The smartphone market continues to expand, as these devices eat into the market share of other types of cell phone. Worldwide smartphone shipments are expected to rise to 1.5 billion units in 2019, up from less than 1.2 billion in 2015, according to IDC. All this means that the opportunity for capacitors in smart phones will continue to expand in the coming years, resulting in rising sales for passives suppliers.