Murata’s solution “Noise Suppression Products”
Steady expansion of noise suppression products for in-vehicle use technologies and know-how sophisticated through development of consumer products being applied to automobile

Mr. Yoshihiro Yamada
Deputy director, sales promotion group, EMI business division, Component business headquarters, Murata Manufacturing Co., Ltd.

As the in-vehicle equipment proliferates because of advancing of vehicle electronification, Electro-Magnetic Compatibility (EMC) related issues increase the complexity. Murata Manufacturing Co., Ltd. has been supporting engineers who are working on EMC measures for automobile and in-vehicle equipments by widely providing noise suppression products that meet the requirements for vehicle use. Murata’s strength resides in technologies and know-how that have been obtained from many years of development of consumer equipments and portable phones. With these technologies, Murata is preparing solutions for problems arising from the latest development of vehicle electronification, such as EMC measures in a high-speed in-vehicle LAN or interference among electronic equipment inside the vehicle

Fig-1. Line-up of EMIFIL^® series as Murata’s noise suppression products (click to enlarge)

Among Murata’s major EMI suppression filters “EMIFIL^®”, inductor type “Chip ferrite beads”, capacitor type three terminal capacitors, T type filters, common mode choke coils, and block type filters are in the market(See Fig-1). All these filters have in-vehicle use components that are different from general purpose consumer use. “We are expanding the line-up of components for in-vehicle use by increasing reliability of our conventional consumer products. Each component guarantees the wide range of operation temperature from -55°C to +125°C and meets “AEC-Q200” standard for electronic components for in-vehicle use. We are developing a reliable production site that is certified by “ISO/TS16949”, a quality control standard.” (Mr. Yamada, Deputy director of sales promotion group, EMI business division, Component business headquarters, Murata Manufacturing Co., Ltd.)

Provides products for conductive adhesive agent

Fig-2. DLW43SH series of wire-wound type chip common mode choke coil(click to enlarge)

Main features of in-vehicle use products are as follows. BLM_SH series of chip ferrite beads is used by inserting in series to a signal line. Besides general purpose products, Murata carries high-speed signal type, large current type, and high frequency use and their size covers wide varieties from 0402(EIA)size type (1.0 x 0.5 mm) to 1806(EIA)size type (4.5 x 1.6 mm) . For chip ferrite beads, Murata also carries BLM18AG_WH1 series for the conductive adhesive agent that has elevated anti-thermal shock resistance. “With an application of Ag/Pd as the surface material of external electrode, we enable it to fit conductive adhesive agent. External electrode for conductive adhesive agent is an example of Murata’s horizontal dissemination of technologies. We also carry conductive adhesive agent products for chip monolithic ceramic capacitor and NTC thermistor.” (Mr. Yamada)

NFM21HC series of three terminal capacitor exercises its power for eliminating high frequency noise from a signal line. NFE61HT series of T type filter is an effective device to eliminate high frequency noise. It is featured by large rated current as high as 2A and can be utilized not only in signal line but also in power line.

Fig-3. BNX024/25H series of block type EMIFIL^® (click to enlarge)

DLW31SH series, DL43SH_XK2 series and DLW43SH_XP2 series of common mode choke coil are well suited to eliminate noise from highspeed differential signal lines (See Fig-2). A block type filter is a device that encapsulated multiple noise suppression products in a small package. Since it exercises its power over wide frequency range from 50kHz to 1GHz, an application to AM radio, high frequency and electrostatic surge is possible with a single device. “This is the most powerful noise suppression product in our current line-up.” (Mr. Yamada) Murata recently added a surface mount type BNX02□H series to its in-vehicle use line-up where its lead type BNX01□H series were the major in-vehicle use product. (See Fig-3)

Reliability improvement by diverse process technologies

Murata’s diverse process technologies are its advantage in developing products with noise suppression for in-vehicle use. “Process technology is one of the important points in achieving high reliability that is required for in-vehicle application. Murata produces highly reliable components with fundamental process technologies for manufacturing noise suppression products such as wire winding technology, laminating technology and thin film forming technology along with carefully thought through design to maximize quality.” (Mr. Yamada) One example is a wire wound type common mode choke coil with a structure in which lead wire is wound around the ferrite core. A printed circuit board (PCB) used in in-vehicle equipment is often sealed with resin such as HumiSeal to protect it from humidity. But, in the case that a PCB, on which wire wound type common mode choke coil is mounted, was sealed with resin, stress might be applied to the mounted component due to the difference of thermal expansion between resin and the component when it was placed in high temperature environment or when thermal shock test is executed. This stress may happen to generate a break of the wounded wire. “In resolving this kind of problem, our unique know-how in process technology such as wire wounding works effectively.” (Mr. Yamada)

Mr. Katsuya Utsumi
Chief of merchandize technology 4th section, Sales promotion group, EMI business division, Component business headquarters, Murata Manufacturing Co., Ltd.

Another advantage is Murata’s know-how and technologies in vast fields acquired through its development of consumer equipments. “Murata enjoys outstanding reputations in noise suppression products for home electronic appliances and mobile phones. We have treated various electronic circuits covering broad frequency band from low to the high frequency of a wireless system. We will be able to resolve most EMC problems regarding in-vehicle equipments with our knowledge and experiences. Against the backdrop of growing demands for smaller and thinner in-vehicle and consumer products, new EMC problems are emerging. It can be said that demands in in-vehicle equipments are coming to coincide with Murata’s specialty” (Mr. Utsumi, Chief of merchandize technology 4th section, Sales promotion group, EMI business division, Component business headquarters, Murata Manufacturing Co., Ltd.)

Designers of in-vehicle equipments should not overlook that Murata not only provides noise suppression products but also actively supports engineers in development of EMC countermeasures. For example, cooperating closely with its noise suppression section, Murata actively provides its customers with EMC/noise countermeasure technologies and know-how. Occasionally, Murata offers clients its cutting-edge measurement equipments and experimental facilities such as three anechoic chambers placed in Yokohama, Kyoto and Fukui. Murata also offers services to provide a file containing a list of full line-up of noise suppression products and numerical constants or parts box at no cost. (See Fig-4) “A majority of EMC measures move into full gear at the final stage of designing. So, many engineers are struggling with EMC/noise countermeasure in their limited time. We believe that it is important to provide such customers with samples of EMC/noise countermeasure product easily and quickly.” (Mr. Utsumi)

Strength in EMC countermeasure for the in-vehicle LAN

Fig-4. Examples of free sample kits provided to users

Especially, common mode choke coil enjoys high popularity among Murata’s various noise suppression products because of its power in EMC countermeasure of in-vehicle LAN such as CAN (Controller Area Network) or FlexRay^®. With the increase of in-vehicle equipment, scale of in-vehicle LAN connecting this equipment is expanding. This trend gives EMC environment negative impacts due to the limited space inside a vehicle. Also the emission problem that noise generated by LAN affects badly to in-vehicle equipments and the immunity problem that includes communication error due to external noise may occur. “Common mode choke coil show its effectiveness in broad frequency range from low to high.” (Mr. Yamada)

In addition to EMC countermeasure for in-vehicle LAN, Murata focuses on problems of mutual interference among the electronic equipments inside vehicles. “We call the problems “Intra-system EMC”. Although we had concentrated mainly on emission and immunity issues of in-vehicle equipments, we need to pay more attention to growing possibility of the occurrence of the noise problems by neighboring equipments as number of in-vehicle equipments increases. The phenomenon is also called as “autointoxication”.” (Mr. Yamada) Murata already launched an investigation of solutions to this problem. “Equipment have to be embedded with noise suppression respectively.” (Mr. Yamada) Murata possesses rich resources regarding noise suppression technology. For example, Murata has thoroughly investigated malfunction of wireless LAN by interference from the noise generated from internal PCB substrate when wireless LAN was introduced into a laptop PC. Regarding a mobile phone that includes a highspeed processor and wireless system within a small body, “autointoxication” is increasing problems of deterioration in communication quality. The company is engaging in various tasks to come up with solutions to this problem. “Increase of in-vehicle equipments will lead to the surge of problems regarding intra system EMC. With our noise suppression products and experiences, we will actively support customers who are facing EMC problems.”(Mr. Yamada)

Fig-5 Common mode choke coil exerting its power in EMC countermeasure of in-vehicle LAN (click to enlarge)

* EMIFIL^® is the trademark of Murata Manufacturing Co., Ltd.
FlexRay^® is the trademark of Daimler AG.