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Power Inductors for Automobiles Race for Reliability

N ew product development of inductors for automobiles has been gathering momentum. Reflecting the increase in the ratio of computerized functions in a vehicle, the number of inductors incorporated in a vehicle has been increasing. According to some manufacturers, more than 100 power inductors, on average, are used in a vehicle today. Various inductors, which are not seen in other products, can be found in vehicles, including high-frequency inductors for wireless communication systems and signal inductors for car navigation systems. Also, as greater number of ECUs are incorporated in luxury cars, more inductors are being used.

With the functional advancement of the safety system and powertrain system, the number of ECUs, in which automotive inductors are used, has increased. Furthermore, amid the trend toward mechatronical integration through the installation of ECUs in the engine room instead of in the cabin, the requirements for highly reliable components for ECUs, with importance placed on environmental resistance, have intensified.

A rich lineup of 150°C-resistant power inductors for automotive use range in size from 3×3mm to 12×12mm.
A rich lineup of 150°C-resistant power inductors
for automotive use range in size from 3×3mm to 12×12mm.

Reliability against High Temperature
Inductors for automotive use are required basically to satisfy AEC-Q200, which is a reliability test standard for automobiles. As reliability is strongly required, inductors for ECUs are now required to have an operating temperature range up to 150°C instead of 125°C. In addition, they are also required to have reliability for vibration resistance and shock resistance, which are requirements unique to automobiles.

Against this backdrop, chip beads and inductors that adopt resin electrodes to achieve 150°C-resistance and the ability to suppress cracks, resulting from mechanical stress and thermal shock, have been developed.

Power inductors are required to satisfy 150°C-resistance, have small and low-profile dimensions, low direct current (DC) resistance, and support high current. Conventionally, power inductors that used Ni-Zn-based ferrite core were predominant. However, against the backdrop of stronger requirements for the support of high current, the development of metal-based power inductors for automotive use has become active. At present, rich lineups of ferrite-based and metal-based power inductors that withstand 150°C are available.

Recently, in particular, the development and adoption of safety systems, such as advanced driver-assistance systems (ADAS), has become active, in light of the practical application of autonomous driving systems in the future. In order to promote high-speed and high-accuracy data transmission of images captured by millimeter wave radars and cameras, a 3225-size common-mode filter for Ethernet has been developed. Furthermore, inductors for automotive power over coax (PoC) applications have also been commercialized. These inductors achieve signal transmission and power supply on a single coaxial cable and are suitable for interfaces of on-board cameras. They have achieved high impedance in broadband optimum for on-board cameras.