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An abbreviation of "alternating current."

AC Input Power Supply

Acceleration Sensor

A sensor that detects acceleration through changes in rotation or motion velocity. Piezoelectric elements are used in addition to semiconductors.

Active Matrix System


A general term for a component that converts a certain energy into mechanical power. Indicates an electric actuator that acquires mechanical motion such as reciprocating motion or lock release from electrical energy, in the field of electrical/electronic equipment. Also called a "plunger", especially in the case of one that acquires reciprocating motion. The actuator incorporating a NEOREC magnet (neodymium magnet) has strong magnetic energy despite its small size. Its coil and spring use a micro current providing excellent high-speed response, and it is used in the disk drive locks of a personal computer or a DVD recorder.

Alternating Current (AC)

A current in which current flow reverses periodically, the same as in commercial AC power supply. A pulse current is also an alternating current, in a broad sense.


An amorphous state that becomes a solid state lacking distinct crystalline structure. Glass is a typical amorphous substance.

Amorphous Core

An amorphous alloy core manufactured by melting and rapid-cooling iron group elements, such as iron, nickel, and cobalt, and small amounts of additional elements. High permeability and excellent in abrasion resistance. Used in special transformer cores, etc.

Amorphous Silicon Solar Cell

A solar battery using an amorphous silicon semiconductor combining hydrogen with amorphous silicon. Although its energy conversion efficiency is inferior to single crystal silicon or polycrystalline silicon, it is used for solar calculators and solar wrist watches because of its high sensitivity to the wavelength of fluorescent light. Thin and flexible, it features excellent processability to any forms.

Anechoic Chamber

A space where external electromagnetic waves are blocked and the interior is also electromagnetically stabilized. Used to measure noise emitted from electronic devices, examine immunity (resistance to external electromagnetic waves) of electronic devices, and so on. Although noise emitted from electronic devices is basically measured in the open air, since anechoic chamber is not influenced by surrounding electromagnetic noise including radio waves from cellular phones, weather conditions, etc., the demand for such environments has been increasing more than ever. Anechoic chamber consists of a metal shield structure to block external electromagnetic force, a radio wave absorber to be installed in the surface of a wall or a ceiling to absorb radio waves emitted in the anechoic chamber, and equipment to implement tests, etc.

Antenna Switch

An element that switches transmission and reception by time sharing in cellular phones. Grouping elements such as an inductor, a capacitor, and a resistor together on a ceramic substrate, it incorporates a PIN diode.

Antenna Switch Module

Integrates the antenna switching device and the high-frequency circumference component of a cellular phone. One integrating an antenna switching part and a front end part is known as a Front End Module.


An assembly of several single-components attaining small-size/light-weight/space-saving and low cost, including a capacitor array, a chip bead array, a three-terminal filter array, and a common mode filter array, etc.


A specification to connect a HDD (hard disk drive) and a personal computer. Serial ATA (SATA) is a specification of the serial transmission system attaining a faster transmission speed.

Axial Lead/Radial Lead

Electronic parts include the types that have a lead (end) for wiring and the SMD type that does not have lead corresponding to a surface mounting. Leads can be classified into two types: one with two leads on both right and left sides (in the direction of the central axis) of an electronic component is called an "axial lead", and one that has two parallel leads in the tangential direction is called a "radial lead."



An impedance-matching element. Balun is a coined term that combines balance and unbalance. An element that combines two circuits with different impedances to facilitate signal feed. It has a similar function to a transformer, but it does not need things like magnetic core due to its high frequency. Things such as a combination of two cpreless coils (resonator) is used instead.

Band Pass Filter (BPF)

Bare Disk

A bare type optical disk without cartridge.


B-H Curve

A magnetic histeresys loop. A curve that expresses the magnetization of a magnetic material when placing the magnetic material such as iron and ferrite into a coil and changing the magnetic field to apply, in a graph. An S-shaped and closed curve with a perpendicular axis as a flux density (B) and a horizontal axis as a magnetic field strength (H). Hard magnetic materials such as hard ferrite used as a permanent magnet have a thick S-shaped curve with wide width, and soft magnetic materials such as a soft ferrite have a thin S-shaped curve with narrow width.

BHmax (Maximum Energy Product)

An index showing potential magnetism strength of a permanent magnet material. The second quadrant of the B-H curve (magnetic history curve) of a ferromagnetic material is called a demagnetization curve. The magnetic energy of a permanent magnet is equivalent to the area of the quadrangle having its vertex in the perpendicular axis/horizontal axis of a graph and one point of a demagnetization curve, and the maximum is called a BHmax (maximum energy product). The S-shaped B-H curve becomes larger and a more thickset square shape with a larger BHmax and a more powerful magnet.


A bonding material to be mixed with powder materials in manufacturing of ferrite products, multilayer chip components, etc. After being multi-layered and cut, it is thermally decomposed before firing. This is called a de-binder process.

Blu-ray Disc (BD)

A new-generation optical disk that records a large capacity with approx. 25GB (gigabyte) on a 12cm-diameter disk by one layer using a purple-blue laser beam (wavelength of 405nm) with shorter wavelength than DVD.

Bond Magnet

A magnet made by mixing and molding powders of rare earth permanent magnets (REC magnet or NEOREC magnet) and ferrite magnets into materials such as plastic and rubber.

Bulk Packaging System

In order to mount chip components on a circuit board surface by using equipment such as a mounter (chip component mounting equipment), a device called feeder is needed to supply chip component one-by-one. Today's mainstream feeder system is called a tape feeder. It supplies from a tape rolled in the shape of a reel that holds chip components. However, this system uses paper or resin materials for a tape, with the problem that these materials become waste after use. On the other hand, a bulk packaging system is one which packs chip components individually and puts them into a case, enabling supply of one at a time from the case.



A capacity that can store a charge in a capacitor. The capacitance of a capacitor increases with the larger area of an electrode, the narrower distance between electrodes, and the higher dielectric constant of the insulator between electrodes. A multilayer ceramic chip capacitor attains a larger area of substantial electrode by layering many electrodes.


One of the three major passive components, together with the resistor and the inductor (coil), it basically consists of two electrodes on both sides of a dielectric (insulating layer). Its capacitance is proportional to the electrode surface area, inversely proportional to the inter electrode distance, and proportional to the dielectric constant of the dielectric. A capacitor has the properties that it can store a charge without conducting a current when direct current voltage is applied, and conducts alternating current. Used in rectification circuits and smoothing circuits of power supply using the property that stores a charge. Also used in filters or impedance matching, using its property of conducting an alternating current. The type using a dielectric ceramic such as barium titanate and titanium oxide as a dielectric is called a ceramic capacitor, and the chip type incorporating many electrodes and dielectrics is called a multilayer ceramic chip capacitor.

Carrier Tape

A paper or plastic tape used in a feeder system that automatically mounts a chip component by a mounter (chip component mounting equipment). Rolled and packed in a reel shape by taping equipment.


An abbreviation of "compact disc." An optical disk of 12cm or 8cm in diameter. Includes types such as the read-only type CD-ROM, the write-once type CD-R (recordable type allowing data to be written only once), and the repeated recording type CD-RW on which data can be repeatedly deleted and rewritten. The maximum capacity is 650MB.


A solid-state material of non-metal and mineral manufactured by heat treatment, like ceramic firing. A highly efficient ceramic obtained by precisely adjusting a material with high purity and advanced control in the firing process is called a new ceramic or a fine ceramic. Among these, one with excellent electromagnetic characteristics is called an electroceramics or an electronic ceramic, and is used as an electronic material.

Ceramic Resonator

Chemical Vapor Deposition

Chip Beads

A chip type EMC countermeasure component that absorbs a high-frequency component contained in a signal and converts into heat using the properties of ferrite. To be inserted in a circuit in series. Called beads because they are originally made by penetrating one shaped like a bead with a hole into a lead wire. Enables noise suppression easily without connecting to ground. Widely used in electronic devices.

Chip Varistor

A chip type varistor used as a countermeasure component against surge noise such as static electricity.

Choke Coil

A coil sends direct current, but in the case of current that changes its flux periodically, it generates a reaction magnetic flux itself to prevent this (self-induction action in electromagnetic induction). Choke means "to block." As a result of the coil withstanding a reaction magnetic flux, magnetic energy is stored in the coil where an alternating current flows. A coil using this action is called a choke coil. Used in power circuits and DC-DC converters in electronic devices.


A circuit element that guides and circulates the entering radio wave to always a right (or always left) terminal using the physical effect of ferrite called Faraday rotation. Also an isolator used in cellular phones that uses the same principle.

Clamp Filter

An EMC countermeasure component to be mounted around a cable to remove noise. Consists of a vertically cut ferrite core of cylinder type.

Coercive Force

Magnetic field strength when magnetizing a ferromagnetic material until reaching saturation magnetic flux density, then adding a reverse magnetic field to cancel out the flux density to zero. One of the indexes showing the power of a permanent magnet. One description of this magnetization process in a graph is a B-H curve describing an S-shaped closed curve. Larger product value of residual magnetic flux density and coercive force produces better permanent magnet material.

Common Mode Filter

A countermeasure against common mode noise that has been becoming increasingly important due to the spread of digital equipment and high-frequency transmissions. A common mode filter is an EMC countermeasure component that does not affect the signal in differential mode and absorbs and removes only common mode noise. Used in a connector part to protect the signal quality in high-speed digital interfaces such as USB2.0, IEEE1394, or HDMI. TDK commercially produces common mode filters using three methods; coil method, thick film method, and thin-film method. The demand for use in in-vehicle LAN, such as CAN-BUS, and Flex-Ray and MOST, has also been expanding in recent years.

Common Mode Filter for HDMI

Since the signal transmission of a HDMI interface is high-speed differential transmission, a common mode noise is generated from a transmission line. Since the specification of the transmission characteristics for HDMI is defined strictly, an advanced countermeasure against noise is required.

Common Mode Filter for In-Vehicle LAN Compatible with High Temperature

A common mode filter that also withstands high temperature in the engine compartment of an automobile. A noise countermeasure component with an important function ensuring safe operation of automobiles dependent on an electrical network.

Common Mode Noise

A conduction noise that invades through power lines or signal lines has two modes: differential mode and common mode. In differential mode it flows through one lead wire and back through the other, the same as the signal current. In common mode, it flows through two lead wires in the same direction through a floor or ground.


Copper Loss

A power loss due to electric resistance of a coil, as seen in transformers and coils.


A core of a transformer, antenna coil, choke coil, etc.. Incorporates soft magnetic materials such as silicon steel, amorphous alloy, and ferrite. A ferrite core is an essential core material in a high-frequency area.

Core Loss

A loss of magnetic energy emitted outside a magnetic field as heat when transformer cores are applied to the field. Known as iron loss in the case of an iron core. Includes eddy current loss and hysteresis loss. Becomes large along with the higher frequency of magnetic field added. Especially eddy current loss increases with the smaller electric resistance of a core material. For this reason, iron group core materials (soft iron and silicon steel etc) can be used only in a low-frequency area, and ferrite is essential in a high-frequency area. NiZn (nickel zinc) group ferrites have higher electric resistance than MnZn (manganese zinc) group ferrites, and they are used more in high-frequency areas. In a transformer, the sum total of core loss and copper loss due to coil resistance is total loss.

Coreless Coil / Coreless System Inductor

A coil without a magnetic substance core is widely called an coreless coil. In electromagnets, a ferromagnetic material such as iron is used as a core, but iron soon saturates its magnetism with the increase in the current sent through a coil. Therefore, in a superconductive magnet that sends a large current, an coreless coil is used. Moreover, although ferrite is used in transformers of electronic devices or cores of antenna coils, a ferrite core of magnetic material has large loss in a high-frequency GHz band. For this reason, an air cored system inductor is used in high-frequency circuits of cellular phones. Includes those using dielectric ceramics of non-magnetic material with a small dielectric constant as an core, in coreless system inductors.



A head reading element for HDD with a new system that exceeds the limitations of TMR heads. A head for HDD is formed by arraying multiple layers for the recording element and the reading element on a wafer. In order to read the magnetic information in a recording layer, a conventional type GMR head sends a sense current to a thin-film layer inplain (CIP system). The CPP-GMR head attains high sensitivity read exceeding TMR heads by sending this current perpendicularly (CPP system).

Curie Temperature (Curie Point)

Heating ferromagnetic materials such as iron and ferrite causes them to lose magnetism on reaching a certain temperature (transition to a paramagnetic material). This temperature is the Curie temperature (Curie point). Heating a permanent magnet to more than its Curie temperature also destroys its magnetism. This is called thermal demagnetization.

Current Sensor

A current detection sensor in protection circuits and control circuits of various devices including switching power supplies.

Custom IC

An IC specially designed and manufactured for a specific use/product. An IC partially using a standard design is called a semi-custom IC.


An abbreviation of "chemical vapor deposition." A method used to form a thin-film of products by mixing gas molecules of materials in inert gas, having them react on a substrate. The method using a gas reaction in plasma electric discharge is called a plasma CVD method. Used in thin-film processes for semiconductor integrated circuits, heads for HDD, and amorphous silicon solar cells.


Data Cartridge


Direct current. An abbreviation of "direct current."

DC-AC Inverter

A device that changes direct current (DC) input into alternating current (AC) output. Although an electronic circuit is usually driven by direct current, some devices need an alternating current. For example, in order to light the cold cathode tube used as a back light in liquid crystal displays, high voltage of approx. 1000V, called a kick voltage, is required. In order to acquire this high voltage, a transformer (converter) is used. However, since a transformer does not function in a direct current, a DC-AC inverter is required to change direct current to alternating current.

DC-DC Converter

A circuit/device that raises or lowers direct current (DC) voltage. Widely used in mobile computing devices in order to acquire sufficient voltage to drive an IC.

DC-DC Converter for HEV/EV/FCEV

Energy saving/eco-friendly cars, such as the HEV (hybrid electric vehicle), EV (electric vehicle), and FCEV (fuel cell electric vehicle), are driven by a motor using the electric power stored in a main battery. (HEV shares the engine as well). A DC-DC converter for HEV/EV/FCEV functions to convert the high voltage (200-300V) of the main battery of these cars into low voltage (12V etc) to operate various in-vehicle electrical devices.


Dielectric Ceramic

Ceramic dielectric material. A general term for certain types of ceramics with high dielectric constant such as barium titanate. Used as dielectric materials placed between the electrodes of capacitors.

Dielectric Constant

When placing a dielectric material between two sheets of electrodes, increased charge can be stored by its polarizing action. A dielectric constant expresses how much charge can be stored at this time, and the ratio in the case of assuming the space of electrodes as a vacuum is called a relative dielectric constant. Usually a dielectric constant indicates a relative dielectric constant. The relative dielectric constant of a barium titanate, that is a high dielectric constant group dielectric, attains even 1,000 to several tens of thousands.

Dielectric Filter

A type of filter formed from a dielectric material with an internal conductor. Mainly used in high-frequency circuits.

Dielectric Material

An insulator that does not conduct current. When placed in an electric field, it polarizes to plus and minus (dielectric polarization).

Different Materials Simultaneous Firing Technology

TDK's original technology, used to laminate and fire sheets with different dielectric constants simultaneously. Requires a very high technology and knowhow in material design and firing process, such as securing high dimensional accuracy or preventing warpage problems due to different thermal expansion coefficients.

Differential Mode Noise

Noise in differential mode (also called normal mode) that flows through two lead wires, one as outward and another as return, the same as a signal current. Generally a differential mode noise exists in a higher frequency range than a signal frequency, therefore a capacitor, chip beads, and an LPF (low pass filter) are used for the noise suppression. A three-terminal filter with a steep frequency characteristic is used when the frequency bands of noise and signal are close.

Differential Transmission System

A system that transmits two signals in which the phase is different by 180 degrees through two lines, not a data transmission of signal by single line (and ground). Also called a balanced transmission system. High-speed digital interfaces such as USB2.0, IEEE1394, and HDMI incorporate a differential transmission system. Although it has the advantage of not being easily influenced by noise, common mode noise is in fact generated due to the slight unbalance of a differential signal, etc.. For this reason, a common mode filter is used in high-speed digital interfaces.


An element that functions to separate a radio wave into the frequency band of each system at the entrance of an antenna circuit in dual band devices where cell phone services through two or more systems can be used by using one set of a terminal. An LC compound component that combines an LPF (low pass filter) and an HPF (high pass filter).

Direct Current (DC)

A current that flows in one direction, from a plus pole to a minus pole, as in a dry cell or a battery.

Direct Current Resistance (Rdc)

A resistance (R) in the case of sending a direct current (DC) through a circuit element.

Direct Current Superposition Property

When a current flowing through a coil wound around the core of a magnetic material such as a ferrite is enlarged, a flux density that a coil generates is increased, but the core reaches its saturation state and looses the properties as a coil. A direct current superposition property is one that shows a relationship between a direct current that flows into a coil and an inductance.

Directional Coupler

A component that controls the output gains of transmission amplifiers automatically by feeding some outputs back in transmission circuits of wireless communication devices such as cellular phones. Enables functions by efficiently combining two inductors and the peripheral capacitor components.

Discrete Track Medium

DTM (discrete track media). The conventional magnetic recording medium for HDD had a problem that magnetic interference from adjacent tracks becomes larger with the narrower track width resulting from improvements in recording density. A discrete track medium essentially solves this problem, enabling remarkable improvement in recording density. By forming a slight slot of a single nanometer in depth in the magnetic layer, it enables physical separation of the recording track, which reduces the magnetic interference of adjacent tracks.


A pulse-height discriminator. An element that senses a pulse signal above a prescribed level.

Door Open/Shut Sensor

A sensor with functions to adsorb and hold door/lid using magnetic energies as well as to turn an electric contact ON/OFF through a built-in reed switch when opening and shutting. Features high reliability by using a reed switch. Includes one type that turns an electric contact OFF when adsorbing through a magnet, and another type that turns ON. Used as a open/shut sensor for a door or a lid in OA equipment, such as copy machines and printers, FA equipment, etc.



A key device to share reception and transmission via one antenna in cellular phones. It functions to share an antenna element by combining a BPF (band pass filter), and separating transmission waves and reception waves. Conventionally, a dielectric duplexer has been used, but today, a smaller and lighter SAW duplexer using surface acoustic wave (SAW) effects through the oscillation of a piezoelectric element is mainly used.

DV Standard

A recording format of cassette tapes for digital video cameras.

DVD (-ROM, -R, -R DL, -RW, -RAM, +RW, +R)

DVD is an abbreviation of "digital versatile disk." An optical disk of 12cm and 8cm in diameter (the same dimensions as a CD). Includes standards such as a read-only type DVD-RAM (for data, for image, and for audio), a write-once type DVD-R, +R (recordable type on which data can be written only once), and a repeated recording type DVD-RAM, DVD-RW, -RW DL, +RW, and +RW DL on which data can be repeatedly deleted and rewritten. A DVD with a storage capacity of 4.7GB (gigabyte) is equivalent to more than seven CDs of 650MB (megabytes).



An abbreviation of "electronic control unit." Usually, an in-vehicle ECU used for automobile electrical control. ECUs were originally used mainly for engine control, then came to be used for various electrical system controls, such as drive systems, body systems, safety systems, and multimedia systems (information and telecommunications systems). From 10 to 70 ECUs are incorporated in recent automobiles, and these are networked by an in-vehicle LAN.


Electric Double Layer Capacitor

An energy storage device having a similar structure to a capacitor that has an activated carbon electrode dipped in an electrolytic solution. Activated carbon with countless holes has a very substantial surface area, enabling a capacity more than 1 million times (farad order) as large as a conventional electrolytic capacitor (microfarad order). Has been considered an extensive application as auxiliary power that supplies a temporary and large current to the drive motor of hybrid cars, or variational adjustment of outputs of photovoltaics or wind power.


A fine ceramics material with electromagnetic characteristics. Examples include ferrite in transformer cores or magnet materials, dielectric ceramics used in capacitors, piezoelectric ceramics used in oscillators or filters. Requires advanced technology in processes such as material design, molding, and firing.

Electrolytic Capacitor

A capacitor using a metal oxide and an electrolyte solution, or a solid electrolyte. Features plus/minus polarity and large capacitance. Includes an aluminum electrolytic capacitor, a tantalum electrolytic capacitor, etc.

Electromagnetic Buzzer

A sound generator combining a magnet, a coil, a diaphragm, etc. Features a wide frequency and a high sound pressure, enabling it to play melodies. Widely used as alarm sounds such as ringers in cellular phones, alarm clocks, OA equipment, and vending machines.

Electromagnetic Inductance

When a permanent magnet is moved in and out in proximity to a coil, electromotive-force (voltage) is generated, current flows into the coil, and magnetic flux occurs. This is called electromagnetic induction. Inductance is a numeric value that shows how much magnetic flux a coil can generate.

Electromagnetic Shield Material

A material used to block electromagnetic. TDK's Flexield is a compound electromagnetic shield material, mixing magnetic material with high magnetic permeability into a resin, in thin and flexible form, enabling highly adaptable processing.

Electronic Buzzer

A small sound converter called a sound generator or a sounducer. Includes a piezoelectric buzzer using a piezoelectric element and an electromagnetic buzzer using a magnet.


An abbreviation of "electromagnetic compatibility/electromagnetic coexistence nature." Generally used to signify noise problems in electronic equipment. Electronic equipment not only suffers damage due to noise, but serves as a source of the noise itself. Therefore, since a digital technology has been developed and trouble due to noise now occurs frequently, in addition to EMI (electromagnetic interference = emission problem), the concept of EMS (electromagnetic interference susceptibility = immunity problem) has appeared. EMC (electromagnetic compatibility) is to attempt to reconcile EMI and EMS. That is, EMC is based on the concept of "not emitting noise affecting another system" as well as "not receiving noise influence from another system." An EMC countermeasure component is used for the countermeasure.

EMC Countermeasure Component

A general term used for a noise countermeasure component such as a capacitor, an inductor, chip beads, a varistor, a three-terminal filter, a common mode filter, or electromagnetic shield material (TDK's Flexield).


Electromagnetic interference.


Electromagnetic interference susceptibility.


Equivalent series capacitance. A capacitor component that does not exist in a circuit diagram is distributed in the coils or terminal electrodes of an inductor or a resistor. Such a capacitor component when inserted in a circuit is called an "equivalent series capacitance." Requires an inductor of low ESC in a high-frequency area.


Equivalent series inductance. Parts, lead wires, and wiring patterns, such as a resistor or a capacitor, also have slight coil effect. This is called equivalent series inductance. It acts as an LC filter and becomes a cause of loss in a high-frequency area.


Equivalent series resistance. An inductor and a capacitor have a DC resistance component (Rdc) due to the resistance of an internal electrode or a terminal electrode. A substantial resistance when inserting in a circuit is called "equivalent series resistance." Requires an inductor and a capacitor of especially low ESR in a high-frequency range.


A method used to form a detailed pattern on a material surface. Methods include the wet etching method using an acid and other etching reagents, the dry etching method using plasma, and the ion milling method using an ion beam. An absolutely necessary technology for thin-film processes of semiconductor integrated circuits, such as IC and LSI, and heads for HDD.

Eye Pattern

A method used to assess whether the differential signal of a digital high speed interface, such as USB2.0, IEEE 1394, and HDMI, is transmitted without waveform distortion. Called "eye pattern", because the form of transmission waveform and central red hexagon resembles a series of eyes. Signal waveform should not appear within the area of a hexagon when a noise countermeasure component such as a common mode filter is inserted.


Feed Through Capacitor

A capacitor with its high-frequency characteristics improved by attaining low ESL (equivalent series inductance). A capacitor, slightly but including its internal electrode or terminal electrode, acts as an inductor, and in digital equipment, the higher-harmonic component (frequency component multiplied by integral number to a fundamental wave) contained in a digital signal serves as noise and emits noise. In order to solve this problem, a feed through capacitor was developed with three terminals structure incorporating ground.


An oxide group magnetic material blending and sintering manganese, nickel, zinc, etc., to iron oxide. Trivalent metal ions and divalent metal ions are arranged in a grid of oxygen ions, and as a result of interplay between those magnetic forces, a magnetism peculiar to ferrite, called ferrimagnetism appears. It includes some types according to crystal structure. A hard ferrite with hard magnetism is used in ferrite magnets, and a soft ferrite with soft magnetism is used in core materials of transformers, antenna coils, choke coils, and common mode filters. Generally ferrite indicates a soft ferrite. A typical soft ferrite includes manganese zinc (Mn-Zn) group ferrite and nickel zinc (nickel-Zn) group ferrite.

Ferrite Core

The core of a ferrite used in transformers, antenna coils, choke coils, common mode filters, etc. Invented in Japan in 1932 and commercialized by the Tokyo Denki Kagaku Kogyo K.K. that is the predecessor of TDK. When a metal group soft magnetic material is used as a core material, the calorific loss due to an eddy current becomes large in a high-frequency range. On the other hand, since a ferrite that is a metal oxide has a large electric resistance with few calorific loss due to an eddy current, it is essential as a core material in a high-frequency range. Various properties include a high magnetic permeability (high µ), a low core loss, a high property in wide temperature range, etc. Especially, a ferrite used as core materials of transformers or choke coils in power circuits operating with a large current is called a power ferrite.

Ferrite for ADSL Modem Transformer

In xDSL including ADSL that transmits sound and high-speed data simultaneously using a telephone line, the quality of the ferrite material used for the transformer core in the modem is very important.

Ferrite for Pulse Transformer for LAN

Ferrite used as core material of pulse transformers in LAN systems.

Ferrite Magnet

A magnet manufactured by forming and sintering powder materials consisting mainly of iron oxides. Excels in cost performance and accounts for 90% or more of the magnet production volume in the worldwide magnet industry by weight.

Ferromagnetic Material

Briefly described, this is a substance that sticks to a magnet. Also simply called a magnetic substance or a magnetic material. Ferromagnetic are roughly classified into a hard magnetic material that maintains its magnetization after sticking to a magnet even when the magnet is removed, and a soft magnetic material that returns to its original state when the magnet is removed. Magnet steel used in permanent magnets and hard ferrite are hard magnetic materials, and soft iron used in transformer cores, silicon steel board, sendust, permalloy, and soft ferrite, are soft magnetic materials. Generally, a ferrite indicates a soft ferrite.


Firing Atmosphere

An ambient gas used in the case of firing a ferrite core and a multilayer ceramic chip capacitor by heat treatment. For example, called a nitrogen atmosphere in the case of providing nitrogen in order to control oxidization. Requires an advanced knowhow and technology in atmosphere control as well as temperature control.


Flexield is a registered trademark of TDK Corporation. A compound electromagnetic shield material with sheet shape that is thin and flexible with excellent processability to any required form by mixing magnetic materials with high magnetic permeability into resin. It suppresses radiation noise from electronic devices over a high frequency range, with excellent performance especially in the high-frequency range. A sheet-shaped noise counter-measure component best suited to laptop computers, digital still cameras, and portable devices such as cellular phones.

Flex Ray

A type of in-vehicle LAN with high-speed and hi-reliability, compatible with the X-by-Wire system that controls steering or brakes by electrical impulses

Flip Chip/Flip Chip Bonder/Flip Chip Mounter

Flyback Transformer

A step-up transformer to accelerate the electron beam emitted from the electron guns of cathode-ray tubes.

Forward System/Flyback System

A circuit system for switching power supply. A forward system sends energy to output when a switching element is ON, and a flyback system sends when it is OFF.


In manufacturing of semiconductor devices, when transferring wafers automatically one after another to various manufacturing equipment, wafers are stored in sealed containers so that particles (fine dust) would not adhere. This container is called a FOUP.

Front End Module

One attaining effective miniaturization by unifying circuits (an antenna switching device, a diplexer, an LPF, etc.) to pretreat signals received from antennas, such as switching of transmitting/receiving or separating frequencies, in cellular phones.


GBDriver (Gigabyte Driver)

A controller LSI controlling a NAND type flash memory. GBDriver is a registered trademark of TDK Corporation.

Giant Magnetoresistance (GMR) Effect

Giant-Magnetostriction Element

The phenomenon that a ferromagnetic material such as iron and ferrite is distorted while its appearance is slightly expanded in the case of a magnetic field being applied to magnetize it, is called magnetostriction (also known as magnetic distortion). A giant-magnetostriction element is a material with a bigger expansion degree of approx. 1000 times greater than the usual ferromagnetic material. Although a piezoelectric material also shows a similar deformation according to voltage, an giant-magnetostriction element has not only a large dimensional change, but also features a high-speed response/high energy conversion capacity.


In a chip conductor with conventional structure, a stray capacitance (capacitor component) is generated between terminal electrode and internal terminal, and that lowers self resonance frequency (SRF) in a high-frequency area. In order to solve this problem, the terminal electrode and an inner conductor of spiral shape are laminated in a longitudinal direction. Has an inductor structure without vertical and horizontal directivity, attaining stray capacitance reduction. Gigaspiral is a registered trademark of TDK Corporation.

GMR Head

A general magnetic head used in present-day HDDs (as a reading element). GMR is an abbreviation of "giant-magnetoresistance effect", that is a reading principle. Heads for HDDs are manufactured by forming a thin-film to a reading head and a recording head on a wafer, using thin-film process technology. Visualizing a hard disk as paper and a recording head as a pen, a thinner brush can write finer characters and recording density is also improved, but in order to read a weak magnetic charge recorded on a magnetic layer, one with higher sensitivity than a reading head is required. However, the conventional type of GMR head has limited capability to record in higher density. For this reason, the TMR head and the CPP-GMR head were developed as a new reading element, as well as the PMR head as a recording element.

Grain Boundary

A boundary containing many crystal grains in polycrystalline materials is called a grain boundary. This grain boundary is deeply involved with electromagnetic characteristics of ceramics or ferrites.

Green Sheet

A thin sheet that serves as a base material to add an electrode or a conductor pattern in the manufacture of multilayer chip components using the sheet method. A green sheet indicates a raw sheet before firing. In the manufacture of multilayer ceramic chip capacitors, a binder is added to dielectric ceramics powder to make a pasty slurry, and this is spread thinly on a carrier film before drying. This is used as a green sheet.



Hard disk drive. Conventionally used as a recording device in personal computers or HDD recorders. Also, small-sized HDDs are used in digital portable music players and so on. Consists of components including a hard disk (a disk having a special magnetic metal thin-film as a record layer) as a magnetic recording medium, a spindle motor that rotates the disc at high peed, a magnetic head that records and reads signals, and a VCM (voice coil motor) to drive the magnetic head.


A high-speed interface that transmits the mass digital image and sound data of Hi-Vision, etc.. A digital television and a DVD recorder can be connected by one cable.


A high-definition TV represented by Hi-Vision. While a conventional television of NTSC system has 525 scanning lines, a HDTV has 1125 or 1150 scanning lines so that a high-definition image can be obtained. The aspect ratio of HDTV is 16:9 of oblong size, while that of a conventional TV is 4:3. The high-definition television broadcasting signal is sent in 1920x1080 pixel format, and a high-definition television of full specifications projects this format as is.

HDV Standard

A recording format of cassette tape used in digital video cameras. Enables recording of a high-definition HDTV image data with the same amount of data as a conventional DV tape. Includes two types; HDV 1080i (interlaced scanning) with 1080 effective scanning lines, the same as digital high-definition broadcasting, and HDV 720p (progressive scan) with 720 effective scanning lines. A personal computer is connected by using a IEEE1394 cable for high-speed digital interface.

Head for HDD

Magnetic head of HDD (hard disk drive) used as a recording device in personal computers and HDD recorders. Manufactured by laminating a thin-film to a recording element to write information in a magnetic recording medium (hard disk) and a reading element to read information, on a wafer. A head for HDD as a final product consists of a chip (called a slider), acquired by cutting a wafer, attached to an arm or a suspension.

High Pass Filter (HPF)


An alternating current or a radio wave with high-frequency. Abbreviated as HF (high-frequency). Generally, indicates hundreds of MHz or more in alternating current and a wavelength of 10m or less in radio wave (high-frequency higerer than ultrashort wave).

High-Frequency Component/Device

A component/device used in high-frequency circuits of communication devices including cellular phones, etc..


Hi-Vision VTR

A VTR that records a high definition Hi-Vision image. Requires approx. 5 times larger recording frequency bands as conventional ones.

Hybrid Thin-Film Multilayer Method

A method used to incorporate passive components such as two or more capacitors and inductors by layering substrates such as dielectric ceramics. Enables reduction of areas or volumes of substrates, adopted as manufacturing processes of several types of modular components.



An abbreviation of "integrated circuit." A compound circuit component combining many active elements, such as transistors and diodes, and passive elements, such as a capacitors and resistors, on a substrate such as a silicon semiconductor substrate. An IC containing from 1,000 to 100,000 electronic components per chip is called "LSI" (large-scale integration). The various types are roughly classified according to function, into digital ICs (memory IC, logic IC, etc.) that process digital signals and analog ICs for analog signal processing used in operational amplifiers (signal amplifying circuit, A/D converter, D/A converter, etc).


A standard of high-speed serial interface standardized by IEEE (Institute of Electrical and Electronics Engineers). Used for fast transfer of image and sound data, and adopted as an interface in AV equipment such as DVD recorders. "i.LINK" is the name of IEEE1394 proposed by Sony.


Electric resistance in AC circuits. In alternating current, capacitors and inductors also have an impedance according to frequency.

Impedance Matching

Impedance matching is necessary to make the impedances (electric resistance in alternating current) of signal transmission side and reception side the same, by adjustment (matching). If the impedances of signal source and of load side are mismatched, reflection and loss of signal will occur. In order to prevent this, an inductor or a capacitor is inserted to match the impedances. Impedance matching is especially important in a high-frequency circuit.


A coil sends direct current smoothly, but in the case of current that changes like alternating current, it generates reverse voltage to prevent current change through the mechanism of electromagnetic induction, and serves as a resistor. This is called inductance. Since inductance is proportional to an alternating current frequency, even a coil with few numbers of turns has a large resistance(impedance) in a high-frequency area.


Inductors are roughly classified into the coil type, with the lead wire in the shape of a coil, the multilayer type that prints and accumulates a coil pattern on a sheet, and the thin-film type, in which a coil pattern is formed on a wafer by using a thin-film process technology. They are also classified according to use, into power supply systems, general signal systems, and high-frequency systems. In power supply systems operating with a large current, the coil type using a copper wire is mainly used. An inductor of general signal system is used in LC filters and resonance circuits that classify only specific frequency, and a multilayer chip type is mainly used where small sizing/thin shaping is required. For an inductor in a high-frequency system, impedance matching in high-frequency circuits is a major application.


A network providing the same environment as Internet within a company or a research institute, sharing information via E-mail and other tools.

In-Vehicle LAN

A system that networks various electrical devices in automobiles. Roughly classified into drive system (power train system), body system, safety system, and multimedia system (information and telecommunications system). CAN-BUS is a body system, and Flex-Ray and MOST are multimedia system in-vehicle LANs.


An equipment that changes direct current into alternating current of arbitrary voltage or frequency. A liquid crystal display uses a DC-AC inverter that changes direct current into alternating current.

Ion Milling

A technology used to form a detailed pattern on a material surface by using a high-speed ion beam in vacuum. Used in manufacturing of semiconductor integrated circuits or heads for HDD.

Ion Plating

A type of physical vapor deposition (PVD). A method used to adhere an ionized substance to a substrate surface by accelerating it in electric field.

Iron Loss


In wireless communication devices such as cellular phones, some signals coming from the antenna reflect in the internal circuitry and flow backwards. An isolator functions to isolate and remove this adverse current component to protect circuits and stabilize operation. It adapts the nonreversible principle of a radio wave called Faraday rotation. The magnetic field of a ferrite magnet and a special ferrite are used in isolators.

ITO( Indium Tin Oxide)

A transparent electric conduction film made of indium oxide/tin oxide. Used in touch panels, etc..


Knock Sensor

A sensor that detects abnormal combustion (knocking) of engines.


LaCo (Lanthanum-Cobalt) Ferrite Magnet

A ferrite magnet provided with the world top class characteristics by adding La (lanthanum) and Co (cobalt) to base materials of Sr (strontium) ferrite magnets.


An abbreviation of "local area network." A network that connects computers, printers, servers, etc., through high-speed lines within offices, research institutes, schools, and so on. One using wireless communications is called a wireless LAN.

LC Filter

A filter circuit incorporating an inductor (L) and a capacitor (C). Includes a low pass filter (LPF) that passes below specific frequency, a high pass filter (HPF) that passes more than specific frequency, and a band pass filter (BPF) that passes only a specific frequency band. Although a filter can be made by combining a capacitor (C) and a resistor (R), using an inductor enables to have a steep attenuation characteristics, attaining a filter of small loss. A three-terminal filter is an EMC countermeasure component grouping elements such as an inductor and a capacitor into one component, to attain high characteristics.


An abbreviation of "liquid crystal display."


An abbreviation of "laser diode (semiconductor laser)." Used as a light source of CD and DVD players/recorders, laser printers, and optic fiber communication devices.


An abbreviation of "light emitting diode." Often used in back lights of liquid crystal displays (LCD) of cellular phones, etc.

Load port

A device that is equivalent to a door (interface) part in the case of conveying wafers in and out between semiconductor devices and FOUPs.

Low Pass Filter (LPF)

Low Temperature Co-Fired Multilayer Substrate

LPF (Low Pass Filter)


An abbreviation of "large-scale integration." Components contained per chip are from 1,000 to 100,000, greatly exceeding IC (integrated circuit). One containing from 100,000 to 10 million electronic components per chip is called VLSI (very large-scale integration). Mainly produced as a mass memory chip, a high-performance microprocessor unit (MPU), etc.

LTCC (Low Temperature Co-fired Ceramic)

A modularization technology used to print and multi-layer the circuit consisting of many elements such as a capacitor and an inductor, on a dielectric sheet (glass ceramic based on alumina). Saves more space than packing elements into a printed circuit board in a high density.

LTO Ultrium (Data Cartridge)

Although magnetic tapes such as cassette tapes and videotapes have been replaced with optical disks such as CDs, DVDs, and Blu-ray Discs, in order to preserve mass data for business and other uses, a backup device using the magnetic tape of the specification called LTO is used. LTO is an abbreviation of "Linear Tape Open", and it includes two specifications: Ultrium suitable for mass storage and Accelius pursuing high-speed access.



A permanent magnet. Although alnico magnets made of metals are sometimes used, ferrite magnets, rare earth permanent magnets (samarium-cobalt magnet, neodymium magnet), and bond magnets made by mixing those powders into materials such as plastic or rubber, are mainly used.

Magnetic Head

An element that records and reads sound/image/data information to a magnetic recording media such as a magnetic tape or a magnetic disk. Although a bulk head for processing magnetic material such as a ferrite is mainly used in tape recorders or VTRs, heads for HDD are manufactured by forming a thin-film to a recording element and a reading element on a wafer, using thin-film processing technology.

Magnetic History Curve

Magnetic Material

A general term for materials that show certain magnetism to non-magnetic materials that does not change to an external magnetic field. Includes ferromagnetic, paramagnetic, diamagnetic, and other materials, but generally, a magnetic material indicates a ferromagnetic material.

Magnetoresistance (MR) Effect

A phenomenon that electric resistance changes slightly when a magnetic field is applied to a ferromagnetic material. The MR head that was the mainstream of reading elements for HDD in the 1990s, practically applied this phenomenon as a thin-film product of ferromagnetic materials. After that, it was discovered that a bigger effect can be acquired by using a special multilayer thin-film, and it was named the giant magnetoresistance (GMR) effect. The reading element of GMR heads for HDD, today's mainstream, adopts this giant magnetoresistance effect.


Also called magnetic distortion. A phenomenon that the outer shape of a ferromagnetic material is slightly expanded and distorted in the case that a magnetic field is applied for magnetization. Giant-magnetostriction element is a new material; its dimension changes approx. 1000 or more times than usual ferromagnetic materials.

Maximum Energy Product

Medium-Voltage Chip Capacitor

A compact chip capacitor designed to withstand high voltage, up to one hundred volts.


A device that incorporates multi-layered actuators and sensors on a substrate. Manufactured using thin-film process technology and thin-film multilayer method. MEMS technology is used in products such as print heads in ink jet printers, servo mechanism of HDD heads, acceleration sensors, etc.


Consists of one or more LSIs (large scale integration) incorporated with a CPU (central processing unit), a memory, and a peripheral circuit. Incorporated in many home electronics including personal computers.


An abbreviation of "multi-input" and "multi-output", new generation wireless LAN technologies. In conventional wireless LAN systems, radio waves disturbed due to the diffused reflection of obstacles may cause reduced transmission speed. A MIMO receives radio waves of diffused reflection and restores the original data signals using two or more antennas on the transmitting/receiving side concurrently, therefore attaining data transmission with high-speed and hi-reliability without extending the frequency band.

Mini PCI Module

Mini PCI is a standard for small expansion cards using a PCI bus that is the bus (data transmission path) standard used inside personal computers.


A memory chip using a magnetic element, unlike RAM, which uses a semiconductor element. Using a tunnel magnetoresistance effect (TMR) that is the principle of the TMR element of heads for HDD. Attaining high-speed reading/writing with low power consumption, and expected to be the next-generation non-volatile/mass memory chip.

Multilayer Ceramic Chip Capacitor

A chip capacitor for SMD (surface mount device) without lead wire, manufactured by thin-film multilayer method, including thick-film printing method and sheet method. Today's mainstream sheet method used to manufacture by arraying multiple layers of a conductive paste made of a thin dielectric sheet and an electrode by turns, and cutting them, then firing.


NAND Type Flash Memory

A flash memory is a non-volatile storage element which retains data even if the power is turned off. NAND type flash memory is suitable for mass data storage, has attained rapid growth since about 2003, and has come to be widely used as a memory card in various mobile devices such as digital still cameras, cellular phones, and portable music players.

NAND Type Flash Memory Controller LSI

A controller LSI that controls a NAND type flash memory.



TDK's brand name for a neodymium magnet that is the most powerful rare earth permanent magnet. Plays an important role in extensive fields including VCM (voice coil motor) to drive heads for HDD, drive motors in EV (electric vehicle) or HEV (hybrid car), and actuators in OA and AV equipment.


Noise in electronic devices includes conduction noise transmitted through source lines or signal lines and radiation noise that radiates from equipment or invades into equipment as electromagnetic waves. Conduction noise includes two types; differential mode (normal mode) and common mode. Common mode noise is becoming especially problematic with the increase in digital equipment and high-frequency, and its importance is increasing.

Noise Countermeasure Component

Non-Magnetic Material Core

A ferrite core is used to raise the inductance of a coil, but high-frequency range loss becomes large. For this reason, a glass-ceramic group non-magnetic material core is used in inductors for high-frequency requiring low loss and high Q characteristics.

NTC Thermistor

A thermistor with a negative temperature coefficient (NTC), meaning that its resistance decreases with a temperature rise. Also simply called a thermistor. An element incorporating semiconductive ceramics, used in temperature sensors or thermometers.


Optical Pickup

An optical pickup is one reads/writes signals by irradiating laser beams to a signal surface in CDs, DVDs, etc. Consists of a semiconductor laser (LD), a light-emitting device, a lens, a beam splitter, etc.

Organic EL Display

EL is an abbreviation of "electroluminescence." A flat-panel display using special organic materials in which the electrons are excited and a light is emitted when a voltage is applied as a luminescence layer. Features not only its spontaneous light type not requiring a back light, but a wide view angle with excellent visibility, as well as high-response without residual image, unlike liquid crystal displays.


Parallel Transmission

A system that collects and transmits data of 16-bits, 32-bits, and so on, using two or more signal lines while carrying out synchronization. More efficient than a serial transmission using one signal line, but a gap arises at the data arrival time of each signal line along with high-speed. For this reason, a differential transmission system using two signal lines is adopted in high-speed digital interfaces such as USB2.0 and IEEE1394.

Passive Matrix System/Active Matrix System

A drive system used to illuminate an organic EL element. A passive matrix system is one that constitutes the electrode lines of a lengthwise direction and a longitudinal direction like a network and drives a pixel in every line. On the other hand, an active matrix is driven by a TFT (thin-film transistor) installed in each pixel.

Patch Antenna

Another term used for a micro strip antenna. A small and flat antenna made by etching metal on a substrate. Used in high-frequency devices with more than microwave, such as Wireless LAN etc.

PC Card

A small card-sized interface used for personal computers, etc. Includes Type I to Type III (Type II is mainly used). There are various types of PC cards such as flash memory, HDD storage devices, modems, and LAN cards, for separate purposes.

Permanent Magnet


Ease of absorption of a magnetic flux (line of magnetic force) in magnetic materials. A magnetic material with high magnetic permeability absorbs a magnetic flux efficiently like a sponge absorbing water. Expressed by the symbol µ; a high µ material of ferrite indicates that it has high magnetic permeability.

Photo Lithography

A technology that exposes and imprints detailed patterns of circuits on a substrate with an application of photographic technology in manufacturing of semiconductor integrated circuits or HDD heads. A related photolithographic device is called a stepper.

Piezoelectric Actuator

An actuator using the properties of a piezoelectric material excellent in displacement precision and response speed. The application has spread to the print heads of ink jet printers, the actuator of servo mechanism of magnetic heads that follow the HDD tracks with high precision, as well as ultrasonic motors and various micromachines.

Piezoelectric Buzzer

A sound generator using piezoelectric ceramics that oscillates due to its distorted outer shape when alternating voltage is applied. Often used as a sound generating component, such as for an alarm sound in electronic equipment. For an electronic buzzer, along with the piezoelectric type an electromagnetic buzzer using a magnet and coil is also used.

Piezoelectric Ignition Element

An element that generates a spark by voltage through piezoelectric effect. Widely used in gas cigarette lighters and gas ranges.

Piezoelectric Materials

Piezoelectric materials are materials that generate electrical voltage in response to applied mechanical stress (direct piezoelectric effect) and that change shape when electrical voltage is applied (converse piezoelectric effect). In addition to crystals such as quartz, certain types of ceramic materials also have these properties and are called piezoelectric ceramics. When alternating current is applied to a piezoelectric material, the material vibrates, and consequently, such materials are used in piezoelectric buzzers and ultrasonic generator oscillators. Also, piezoelectric receivers in mobile phones and ceramic resonators are electronic components that use piezoelectric ceramics.

Piezoelectric Receiver

A sound generator using the oscillation of a piezoelectric material. Used in receivers of cellular phones and information devices to generate voice, melodies, and alarms.

Piezoelectric Transformer

A converter that converts alternating voltage of the primary side into the oscillation of a piezoelectric material and returns the oscillation to an electrical signal on the secondary side. Simple structure and suited to small-sizing/thin-shaping. Has the advantage that it does not generate electromagnetic noise even under high frequency.

Plasma CVD Method

Plastics Magnet

A bonded magnet made by combining powders of rare earth permanent magnets (REC magnet and NEOREC magnet) or ferrite magnets with plastics and molding (compressing, extrusion, injection molding, etc). The magnetism is inferior to that of simple substance magnets, but thin-shaped or complicated-shaped products can be manufactured, as used for small motors.

PMR Head

A recording element for HDD using a perpendicular magnetic recording (PMR) system. Enables a remarkable improvement in surface recording density compared with the conventional longitudinal recording mode with magnetic recording horizontally to a recording layer. Uses a new medium with a backing layer of a soft magnetic material for a magnetic recording medium.

Polycrystalline Material

A solid-state material consisting of many fine crystal grain aggregates. A ceramic or a ferrite is a polycrystalline material manufactured by firing powder materials. The boundary of crystal grain is called the grain boundary.

Power Ferrite

Ferrite used as core material in transformers or choke coils of power circuits operating with a large current.

Power Integrity (PI)

Power supply quality. In addition to signal integrity (SI), a new concept and its technology currently emphasized as a countermeasure against EMC.

Power Supply Inductor

An inductor designed to be suitable for power circuits and DC-DC converters. The coil type is mainly used due to large current flow. A power supply inductor is now often used to drive an IC, due to multifunctionalization in electronic devices.

PTC Thermistor

A thermistor using an element with positive temperature coefficient (PTC) in which the resistance increases with temperature rise. Manufactured using such material as a semiconductive ceramic that has barium titanate as its major component. Makes it possible to set a temperature where resistance changes suddenly according to material composition, widely used as a temperature sensor and a low-temperature heating device etc. So-called ceramic heaters use PTC thermistors.

Pulse Transformer

A transformer designed to transmit a pulse wave that functions for digital signals. Since a pulse wave, that is a square wave, consists of a fundamental wave and a higher harmonic, that is multiplied by the integral number of the fundamental wave, and requires a pulse transformer with an outstanding transmission characteristic in a wide frequency range, a special ferrite core is used.


An abbreviation of "physical vapor deposition." Used as a method to form a thin-film on a substrate. Ion plating is a type of CVD.


Q Value

A quality factor exhibiting one of the performances of an inductor or a capacitor. An inverse number of loss factor (tangent delta). For example, in inductors, a lower resistance or a larger inductance has a higher Q value in the frequency. A high Q inductor is required, especially in a high-frequency circuit.


Radial Lead

Radio Wave Absorber

A material such as ferrite and carbon that absorbs electromagnetic energy in radio waves and changes it into heat is called a radio wave absorption material. A radio wave absorber includes base materials such as a styrene foam, a foaming polyethylene, and an inorganic material. Various types are available to meet various requirements and applied frequency. A compound type combining two or more radio wave absorption materials, such as ferrite and carbon, has excellent radio wave absorption features in a wide frequency band, and is used in echoic chambers, etc. Moreover, a ferrite wave absorber sintered in the shape of a tile is attached to surfaces such as building walls, to prevent ghost images caused by the reflections of TV radio waves, and so on. A radio wave absorber panel for ETC is also used in highway tollgates.

Radio Wave Absorption Panel for ETC

In the ETC (electronic toll collection) system used on highways, etc., when a radio wave emitted from the antenna of a tollgate reflects off the ceiling or wall of the gate, the in-vehicle terminal of a vehicle passing through the gate may not operate correctly. In order to prevent such a radio wave reflection, TDK's radio wave absorber panel for ETC has been developed. It integrates a highly efficient wave absorber and an easily-mounted panel. A transparent radio wave absorber panel for ETC incorporating a resistance film and a plastics base material is also available.

Rare Earth Magnet

A permanent magnet consisting of compound elements of rare earth group elements, such as samarium and neodymium, and iron group elements such as iron, nickel, and cobalt. Manufactured by molding and sintering powder materials, resulting in the strongest magnetic energy (energy product) in a permanent magnet. Mainly includes a samarium/cobalt magnet and a neodymium magnet (neodymium, iron, and boron magnet). Commercially produced by TDK as REC series and NEOREC series, respectively.


REC Magnet

TDK's brand name for a samarium-cobalt magnet, a rare earth permanent magnet. Its magnetic energy is a little inferior to neodymium magnets, but it features excellent corrosion resistance, without deteriorating its characteristics even if tooled.

Residual Magnetic Flux Density

After magnetizing a ferromagnetic material such as iron or ferrite to reach its saturation magnetic flux density, even if the current is weakened to return the magnetic field to zero, the ferromagnetic material remains magnetized. The flux density, called a residual magnetic flux density, is an index that shows the level of magnetic energy as well as the coercive force in a permanent magnet.


One of the three major passive components, along with the capacitor and the inductor (coil). Resistors used in electronic devices are compatible with surface mount technology (SMT), and the thick-film chip type is mainly used.


An IC is driven by a clock signal (reference signal) with a certain constant frequency. A resonator oscillates this clock signal. A small chip resonator using piezoelectric ceramics is used in digital equipment.


An abbreviation of "radio frequency." Also used to signify "high-frequency" in communication devices.

RF Front End Module


A system that reads ID information by radio frequency (RF). Communicates signals between RFID tag (IC tag) with small IC and reader/writer side by short distance wireless communications. Features greater information processing than a bar code, as well as writing/rewriting information. Non-contact IC cards such as Suica and ICOCA of JR (Japan Railways) or Edy-type electronic money are examples of RFID systems using the technology called FeliCa. Also used in the cellular phones with wallet function called "Osaifu-Keitai".

RoHS Directive

Restriction on Hazardous Substances to health imposed by the European Union (EU). RoHS is an abbreviation of "Restriction on Hazardous Substances." Effective from July 1, 2006, this Directive bans the use of six specific hazardous substances in electric and electronic devices and products handled within the EU. These six substances are lead, mercury, cadmium, hexavalent chromium, PBB (polybrominated biphenyls), and PBDE (polybrominated diphenyl ethers).

Rubber Magnet

Rubber magnet. A bond magnet made by mixing powders of ferrite magnets and molding into rubber, etc. Can be cut or bent freely for processing.



Saturation Magnetic Flux Density

When placing a ferromagnetic material such as iron and ferrite into a coil and enlarging a current sent into a coil, the magnetization intensity of the ferromagnetic material also becomes larger gradually and is finally saturated. The flux density of the ferromagnetic material at this time is called a saturation magnetic flux density. Using a core material with large saturation magnetic flux density in transformers enables reduction of core cross sections or numbers of turns in coils as well as volumes.

SAW Filter

A filter for high-frequency using a surface acoustic wave (SAW) due to the oscillation of a piezoelectric ceramic. Used in televisions, high-frequency circuits of cellular phones, etc..

Self-Resonance Frequency (SRF)

Since an actual inductor has a capacitor component, such as stray capacitance between coils, that does not appear in circuit diagrams, it acts the same as an LC oscillator circuit, and its impedance increases remarkably in a certain frequency in the high-frequency range. This frequency is called a self-resonance frequency (SRF). An inductor functions within a range of self-resonance frequency. Therefore, one with a high self-resonance frequency is required in inductors used in the high-frequency range.


A substance with interim properties of electric conductors, such as silicon, germanium, and selenium, and insulators is called a semiconductor, and active elements such as diodes and transistors using them are called semiconductor devices. An IC or an LSI is one formed of many semiconductor devices on a silicon wafer that is a semiconductor. A semiconductor, such as gallium arsenide or a gallium nitride, consisting of two or more types of elements is called a compound semiconductor.

Serial ATA (SATA)

A standard for connection of an HDD (hard disk drive) and a personal computer. While the conventional ATA uses a parallel system that has a limitation in improvement in transmission speed, the SATA attains improved transmission speed by using a serial transmission system. Since an SATA is a differential transmission system, a common mode filter is used as a countermeasure against noise.

Serial Transmission

A system that sends a signal by bit sequentially through one signal line and a ground. Also a term for a parallel system that collects and transmits the data of 16-bit or 32-bit through two or more signal lines while synchronizing.

Sheet Method

Methods to manufacture multilayer chip components include the thick-film printing method and the sheet method. The sheet method is one that arrays multiple layers of an electrode and a conductor pattern, etc., on a thin sheet called a green sheet.

Shock Sensor

A sensor using the principle that a voltage is generated from a piezoelectric element when mechanical oscillation is added.


Signal Integrity (SI)

Signal quality. A new concept applying its technology as a countermeasure against EMC as well as to ensure power integrity (PI = power supply quality).

Silicon Disc

A card-type flash memory to be inserted in a slot, or a device with the function that can be called a removable HDD (hard disk drive) using a mass semiconductor memory.


The method used to mount an electronic component on a circuit board is called surface mount technology (SMT), and an electronic component compatible with this is called a surface mount device (SMD). Since most SMDs are small chip types without lead wire, this term means almost same as chip component.


Soft Magnetism


A solenoid coil. A rolled cylindrical coil.

Sound Generator

A sound converter that emits an alarm and a melody. TDK's sound generator products include a piezoelectric buzzer and a piezoelectric receiver using piezoelectric elements and an electromagnetic buzzer using a magnet.

Spin Coat

A method used to coat a thin-film by applying a material solution to a rotating substrate at high speed and dispersing the solution by centrifugal force. Used in manufacturing of recording layers of CD-R, for example.


A method used to form a thin-film by making a high-speed ion collide with metal in a low-pressure gas and adhering the released metal atoms to a substrate. Spatter means "sprinkle." The metal used to make ion collide is called a sputtering target.

Sputtering Target



A photolithography device used in photolithography process in manufacturing of semiconductor integrated circuits or heads for HDD.

Stray Capacitance

A hidden capacitor component in the structure of circuits or electronic components such as a coil, an internal electrode, a terminal electrode, a lead wire, etc. A stray capacitance may affect by building a resonance circuit with the resistance component of conductors and so on, and therefore desired to be small in the high-frequency range.

Super Hard

Super Hard Coating

Surface Mount Technology/Surface Mount Device

Surface Potential Sensor

A sensor that controls the electrostatic charge amount precisely by detecting the potential of a photosensitive drum without contact in color copiers or laser beam printers.

Switch Catch

Switching Power Supply

A direct current stabilization power supply using a switching operation (ON/OFF operation in transistors). Also called a switching regulator. A device that acquires the output of prescribed stable voltage and current from commercial power supply sources (AC100V/200V) or DC power supply sources. Its size and weight can be reduced since it does not require a heavy and bulky power transformer like its similar device, the series power supply (series regulator). Moreover, it excels in energy efficiency, widely used as a power supply for various electronic devices such as information devices including OA equipment, FA equipment and personal computers. Includes a forward system and a flyback system according to circuit system, and a unit type, an onboard type, and a module type according to appearance, size, and use. Since a switching power supply generates a high frequency noise called switching noise with the operation of a transistor, it is required to take all possible measures against noise.

System-on-Chip (SoC) / System-in-Package (SiP)

An accumulation of active components such as an IC or passive elements such as a capacitor and an inductor in one chip (SoC), and one grouping every system in one package (SiP), by using a semiconductor manufacturing technology and LTCC technology. A next-generation technology breaking through in small-sizing of electronic devices.


Tangent Delta (tanδ)

A loss factor. One of the indexes showing the properties of an electronic material. For example, in the case of ferrites, generally one with high permeability is excellent, but hysteresis loss to an external magnetic field change is also related to the properties. The ratio of this loss to permeability is called the tangent delta (tanδ), and for materials used in the high-frequency range, this numeric value should be small. Moreover, in capacitors, an energy heat loss based on the delay of dielectric polarization in an alternating current electric field of a dielectric is expressed as a loss factor (inverse number of Q value), and the loss becomes smaller with the smaller numeric value.

Tape Feeder System

A system used to take out a chip component held in a carrier tape and automatically mount it using a mounter (chip component mounting equipment).


A unified power supply products brand launched in 2006 through the joint production of Densei-Lambda, a specialized global power supply producer, and TDK,.

Temperature-Responsive Lead Sensor

A temperature sensor with a contact combining a small ferrite magnet, a temperature-responsive ferrite, and a lead relay. Ferrite loses its ferromagnetic properties at above Curie temperature. A temperature-responsive ferrite is a soft ferrite with a Curie temperature lowered to close to the normal temperature. The lead relay contact is opened/closed at operating temperature. Widely used in intermittent temperature control in thermal rice cookers, the exterior units of air conditioners, and toilet seats with warm water cleansing function.


Total Harmonic Distortion


An element that changes its electrical resistance according to temperature. A coined term combining heat (thermal) and resistance (resistor). Includes the NTC thermistor with a negative temperature coefficient (NTC) that decreases its resistance with a temperature rise, and the PTC thermistor with a positive temperature coefficient (PTC) that increases its resistance with a temperature rise. The NTC thermistor is often used in temperature sensors or thermometers etc, and generally a thermistor indicates an NTC thermistor.

Thick-Film Printing Method

Methods for manufacturing multilayer type electronic parts include thick-film printing method and sheet method. The thick-film printing method prints and accumulates a base material and an internal electrode by pasting the materials, such as a ferrite and a metal conductor, in a similar method to screen printing.

Thin- Film Common Mode Filter

A common mode filter that is formed by condensing fine thin-film inductors and such on substrates like ferrite, with the application of the thin-film process technology cultivated by manufacturing of heads for HDD. Super-small size with an outstanding noise suppression effect that suppresses the influences on transmission signals thoroughly.

TMR Head

TMR is an abbreviation of "Tunnel MR (magnetoresistance effect)". Using a tunnel phenomenon through quantum mechanics creates a magnetic resistivity showing a head sensitivity three times greater than that of conventional type GMR elements, enabling more accurate reading of a high-density signal.


Magnetic recording of HDD can be attained through a procedure that applies a magnetic field to a recording layer on a hard disk, that is a recording medium, from a recording head which magnetizes and arrays mini-magnets on a recording layer horizontally. This is called the longitudinal magnetic recording method. However, because the longitudinal magnetic recording method has density limitations, a perpendicular magnetic recording (PMR) system that arrays mini-magnets perpendicularly on the recording layer was developed. A PMR head is used for this perpendicular magnetic recording. A TMR-PMR head is a combination of a TMR head, that is a reading element with high sensitivity, and a PMR head. A perpendicular magnetic recording system is attained by combining the use of a PMR head and a recording medium, using a special recording medium with a backing layer of soft magnetic material.

Toner Concentration/Residual Volume Sensor

A sensor used to maintain a proper color reproduction and a stable copy quality in color copiers. Includes a toner sensor functioning by a differential transformer system using a highly efficient ferrite core and a residual volume sensor by a piezoelectric oscillating system that detects a residual volume with high precision regardless of particle size and specific gravity of toners.


A doughnut-shaped core or a coil wound around the core.


When two coils are wound around a ring shape core and a change occurs in the current sent through one coil of the two, an electromotive force occurs in the other coil through the flux change of a ring shape core. This is called a mutual induction (a type of electromagnetic induction). A transformer is a device that adapts this principle, converts an alternating voltage or an impedance by combining two or more coils with a common magnetic circuit. Various types include inverter transformers, pulse transformers, rotary transformers, and flyback transformers, as well as power transformers, and use ferrite core material according to function in order to reduce transformer loss.

Transformer Loss

The total sum of core loss, that is the loss from a core, and copper loss due to electric coil resistance, as overall loss from the whole transformer.

Transponder Coil

An antenna coil with small size and high sensitivity, used in tire pressure monitoring systems (TPMS) of automobiles, immobilizers, passive keyless entry (PKE), etc.


Ultra Wide Band

Ultrasonic Adhesion/Ultrasonic Welding

A method used to melt and join materials using friction and impulsive forces through supersonic oscillation. Applied to IC lead wire bonding, etc..

Ultrasonic Flip Chip Mounter

The mounting method that incorporates an IC on a printed circuit board as a bare chip (where a lead wire is not attached) is called a flip chip system, and a mounting equipment of this flip chip system is called a flip chip bonder. Enables reduction of mounting area and space-saving on a printed circuit board, compared with a wire bonding system.

Ultrasonic Humidifier Unit

One adopting the phenomenon that when placing electrodes on both sides of a piezoelectric ceramic and adding a high-frequency voltage, an oscillation occurs in the thickened direction through a piezoelectric effect. When an oscillator generates an ultrasonic frequency under water, a mist is released from the water surface. Features that the diameter of the mist drop is finer than that of natural mist. Used in medical treatments such as inhalers besides home humidifiers. Also called a nebulizer.

Uninterruptible Power Supply


Uninterruptible power supply. A device that backs up systems by supplying power instantly when power stops due to power failures caused by, for example, lightning strike.


An abbreviation of "ultra wideband." Also called an ultrawideband wireless. A short-distance wireless radio communication system using radio waves of extremely wide band but with weak transmission strength (below the noise from personal computers). The transmission speed exceeds 100Mbps, enabling a live transfer of Hi-Vision images. Anticipated to become a new generation technology with high-speed and mass data communication attaining wireless data transfer in various digital equipment including wireless USB. However, since UWB communications overlap with the frequency band that other wireless communications use, it is strictly defined to suppress the radio wave intensity in order to avoid interference.


Vapor Deposition

A method used to form a thin-film by heating metal and other materials in a vacuum and adhering the evaporated atoms and molecules to a substrate. Also called a vacuum deposition.


Short term for an element that changes its resistance according to voltage. An element that shows a high resistance to a certain voltage, and in the case of exceeding the voltage, the resistance is suddenly reduced, sending a large current. Used to prevent such incidents as malfunctions in circuits or destruction of ICs due to lightning, or a static electricity surge, that invades as an unusually high voltage momentarily. Consists of a semiconductive ceramic covered with an electrode. The SMD type chip varistor is small with high electric strength, and demand for it has expanded, as a replacement for zener diodes used conventionally.


Voltage controlled oscillator. An essential component to precisely control oscillation frequency from a synthesizer (circuit that makes specific frequency) in cellular phones, in order to receive radio waves of specific frequency from base stations.

Voltage Control Oscillator



IEEE-802.16 standard. A fixed wireless communication protocol that covers a wide area of approx. 50km in radius with a single antenna (transmission speed is a maximum of 70 Mbps). Called a wireless MAN (Wireless Metropolitan Area Network) in comparison to a wireless LAN used indoors. Assumed to be used in the last one mile where broadband services are not available, such as on mountain slopes and in depopulated districts.

Wireless LAN

Wireless LAN. A LAN without interconnection cable between devices using wireless communications by radio waves. The standards of IEEE802.11b and IEEE802.11g using the radio waves of 2.4GHz bandwidth, and IEEE802.11a using the radio waves of 5GHz bandwidth are used in wireless LANs connecting personal computers and peripheral devices. IEEE802.11n is a next generation high-speed wireless LAN with a transmission speed of over 100Mbps using a MIMO technology.

Wireless USB

One of the facilities with the convenience of USB2.0 that connects personal computers and other digital equipment mutually by wireless communications. Uses UWB communications, meaning short-distance wireless communications with high-speed and large capacity.


X8R-type Multilayer Ceramic Chip Capacitor

The permissive variation in capacitance in multilayer ceramic chip capacitors is determined by use temperature range. X8R has a strict standard that capacitance cannot vary by more than 賊15% over a temperature range of -55 to +150°C. This meets the high temperature environment of the engine compartment of automobiles.


An airplane pilot operates engine throttle and wing flaps by controlling an actuator according to electrical signals through electrical wiring from the cockpit. This is called "fly-by-wire." Also in the automotive field, there is a movement toward changing brakes or steering, conventionally controlled by oil pressure to an electrically-driven type, known as "X-by-wire." Flex Ray is a drive system in-vehicle LAN compatible with "X-by-Wire" era.


µ (mu)