Leaders' Ambitions

Every Device Is Now Being Networked With the Increasing Need for EMI Suppression, the Answer Is Coming into View

Kenichi Mizuno Vice President and Director,EMI Filter Division,Components Business Unit

Mizuno joined Fukui Murata Manufacturing in 1983, where he worked in development, production technology, and product engineering for multi-layer ceramic capacitors. Between 1995 and 2000, he worked at the Murata Plant in the UK. He was appointed Director for Capacitor Division 2 in November 2009. He has been serving as Vice President since July 2012 and as Director of the EMI Filter Division since July 2013. Mizuno’s favorite pastime is gardening.

The development of noise suppression technology at Murata was started with noise filters exploiting functions of capacitors.
In the course of time, we also commercialized inductors using winding technology.
In addition, ferrite material and monolithic technologies have been introduced to expand the product lineup.
Our new goal is to provide highly reliable components and products for higher power lines capable of competing in the automotive and energy markets.
Extending its perspective to cover future markets, Murata is strengthening its efforts to accommodate increasing demand.

Supplying Diverse Noise Suppression Components to Meet Different Market Needs

The development of noise suppression components at Murata began with noise filters exploiting the functions of feed-through capacitors. In the 1960s, the lineup of our capacitor-type noise filters was diversified as color TV broadcasting began in Japan and IC desktop calculators launched.

In the mid-70s, Murata went beyond the field of noise suppression components by commercializing a winding type chip inductor (chip coil). The company also used this inductor technology to composite products combining filters for power supplies. Around 1980, electromagnetic noise became a social problem with the spread of PCs and video game consoles, and more stringent noise regulations were introduced. Against this background, Murata commercialized lead type ferrite bead using a ferrite material to suppress higher frequency noise. In the mid-80s, chip ferrite bead and three-terminal capacitors were introduced to meet downsizing requirements in equipment such as notebook PCs. In the late 90s, high-speed differential signal transmission was spread to transmit large quantities of information such as high-resolution images. In keeping with this trend, Murata derived common mode chokes from chip inductors. The common mode choke coil represents another category of noise suppression components.

In this way, the MurataEMIFilter Division’s business first started with capacitor type noise suppression components, then developed another successful segment of inductors, and finally expanded the lineup of noise suppression components based on inductor technology.

Two Core Products Each in the Noise Suppression and Inductor Categories

The core products in the noise suppression category are ferrite bead and common mode choke coils. The former separate the signal from noise by taking advantage of their difference in frequency. The latter suppress noise using the signal-noise difference in conduction mode. Both are inductor type noise filters.

Inductors can also be divided into two groups depending on whether they are used in power or signal lines. Power inductors are used in lines connecting ICs and power supplies. More precisely they are used for power supply circuits that drive ICs. By contrast, RF inductors are used for exchange of radio-frequency signals in equipment such as wireless devices.

In a smartphone, for instance, there are at least 100 components, including inductors and noise suppression components, that stabilize signal reception and the power supply. Murata produces these products using three kinds of processes — winding, monolithic and film — to provide an optimal product design depending on the characteristics and performance required.

Chip Ferrite Bead

Unlike traditional coils made of wound wires, ferrite bead are simply hollow beads or cylinders made of a magnetic material known as ferrite. They are used by passing lead wires through them. Chip ferrite bead are variants of the ferrite bead. Ferrite sheets with printed coil patterns are laminated and fired into a three-dimensional layered coil structure. The internal coil structure allows these components to achieve high impedance. This structure is basically the same as that of a monolithic type chip inductor, but the difference is that the ferrite material used is better suited to suppress noise.

Common Mode Choke Coils

Noise flows through wiring in either of two modes. In normal mode (differential mode), it is generated in signal and power supply lines and flows through them in opposite directions. In common mode, it flows in all lines — whether signal, power, or ground lines — in the same direction. Common mode choke coils act only on common mode noise. Even when the frequencies of the signal and noise overlap, if they are conducted in different modes, common mode chokes can separate them. Common mode choke coils are made up of two wires wound around a single core in opposite directions. When common mode currents flow through the coils, magnetic fluxes are generated in both coils in the same direction and therefore added together.

"To open up a bright future, we focus our resources on promising fields."

In a World Where Inter-device Communications Are Matter of Course EMI Filter Division Products Play an Increasing Role

Products from theEMIFilter Division can expect a further increase in demand in the future. We often hear the term “Internet of Things” (IoT) these days. The interconnection of all things via the Internet is now attracting attention as a platform for new services and business models. Experts predict a future networked society where not only traditional PCs, servers, feature phones, and smartphones, but also IC tags, ubiquitous applications, embedded systems, various sensors, transmitters, and receivers exchange information with one another on an M2M (Machine to Machine) basis to help create new value. The development toward this vision will naturally increase demand for noise suppression components in electronic devices.

In an IoT world, everything connects and communicates with everything else, and is controlled by one another. Inter-device communications will become a matter of course, leading to a further increase in communication speed. Higher speed means higher traffic, resulting in greater needs for noise suppression. All this brings bright prospects in various fields, including HEMS (Home Energy Management System), BEMS (Building Energy Management System) , intelligent traffic systems, smart communities and wellness. Demand will increase not only for noise suppression components of course, but also for capacitors and inductors.

Targeting “Future Markets”: From Mobile Devices to Automotive and to Energy Applications

The Murata EMI Filter Division’s business should focus on two markets: One is consumer electronic equipment featuring compact size and high mount density, with an emphasis on mobile devices. The other is automotive electronics and industrial electrical equipment such as communication infrastructure. The first group represents a large portion of Murata production. While firmly maintaining these products, we will enhance the second pillar. We are also keeping a watchful eye on the energy market, which is related to environmental preservation, and medical and healthcare markets. Despite its small size, the market for satellites and booster-rockets is also interesting. Components used in these products are each required to deliver high reliability, i.e., failure resistance. In the automotive market and market for industrial electrical equipment, we will need to provide higher power components that can accommodate higher voltages and currents. To better meet market needs, we will need to change many aspects of our operations, including, for example, design, evaluation, and production methods, as well as product inspection methods. I believe we must create and develop more original ways of manufacturing.

In addition to these two markets, our Medium-term Plan also eyes “future markets.” We must anticipate — if vaguely — fields where markets will likely emerge in the future. To open up a bright future, we must focus on potentially promising fields and concentrate our resources into them. To this end, we will endeavor to forge partnerships with research institutions in the public and private sectors and create relationships with players in upper layers of the industry.

EMI (Electromagnetic Interference)

“EMI” stands for electromagnetic interference. EMI filters are used to eliminate electromagnetic interference. In recent years, everyday life is flooded with electronic devices, leading to an increased use of digital circuits through which high-frequency currents flow. As these currents pass through substrate wiring and cables, these paths serve as antennas, emitting electromagnetic waves. These waves may adversely affect other electronic devices that are in use nearby. For example, when a PC is placed near a radio receiver, noise may be generated in the radio’s sound. This is caused by noise produced in the digital circuits of the PC, which is emitted as electromagnetic waves. These waves are then picked up by the antenna of a radio receiver. When strong waves affect a digital circuit, the digital signal waveform may be changed, causing the digital circuit to malfunction. Noise problems can be caused not only by electromagnetic waves conveyed through space, but also between devices connected using signal/power cables.