Showing papers on "Magnetic core published in 2005"

Fabrication of uniform magnetic nanocomposite spheres with a magnetic core/mesoporous silica shell structure.

Abstract: A novel kind of magnetic core/mesoporous silica shell nanospheres with a uniform particle diameter of ca. 270 nm was synthesized. The inner magnetic core endues the whole nanoparticle with magnetic properties, while the outer mesoporous silica shell shows high enough surface area and pore volume. The synthesized material is expected to be applied to targeted drug delivery and multiphase separation. The storage and release of ibuprofen into and from the pore channels of the mesoporous silica shell, as a typical example, are demonstrated.

Inductors and Transformers for Power Electronics

Abstract: FUNDAMENTALS OF MAGNETIC THEORY Basic Laws of Magnetic Theory Magnetic Materials Magnetic Circuits References FAST DESIGN APPROACH INCLUDING EDDY CURRENT LOSSES Fast Design Approach Examples Conclusions Appendix 2.A.1: Core Size Scale Law for Ferrites in Non-Saturated Thermal Limited Design Appendix 2.A.2: Eddy Current Losses for Wide Frequency Appendix 2.A.3: MathCAD Example Files References SOFT MAGNETIC MATERIALS Magnetic Core Materials Comparison and Applications of the Core Materials in Power Electronics Losses in Soft Magnetic Materials Ferrite Core Losses with Non-Sinusoidal Voltage Waveforms Wide Frequency Model of Magnetic Sheets Including Hysteresis Effects Appendix 3.A: Power and Impedance of Magnetic Sheets References COIL WINDING AND ELECTRICAL INSULATION Filling Factor Wire Length Physical Aspects of Breakdown Insulation Requirements and Standards Thermal Requirements and Standards Magnetic Component Manufacturing Sheet References EDDY CURRENTS IN CONDUCTORS Introduction Basic Approximations Losses in Rectangular Conductors Quadrature of the Circle Method for Round Conductors Losses of a Current Carrying Round Conductor in 2-D Approach Losses of a Round Conductor in a Uniform Transverse AC Field Low Frequency 2-D Approximation Method for Round Conductors Wide Frequency Method for Calculating Eddy Current Losses in Windings Losses in Foil Windings Losses in Planar Windings Appendix 5.A.1: Eddy Current 1-D Model for Rectangular Conductors Appendix 5.A.2: Low Frequency 2-D Models for Eddy Current Losses in Round Wires Appendix 5.A.3: Field Factor For Inductors References THERMAL ASPECTS Fast Thermal Design Approach (Level 0 Thermal Design) Single Thermal Resistance Design Approach (Level 1 Thermal Design) Classic Heat Transfer Mechanisms Thermal Design Utilizing a Resistance Network Contribution to Heat Transfer Theory of Magnetic Components Transient Heat Transfer Summary Appendix 6.A: Accurate Natural Convection Modeling for Magnetic Components References PARASITIC CAPACITANCES IN MAGNETIC COMPONENTS Capacitance Between Windings: Inter Capacitance Self-Capacitance of a Winding: Intra Capacitance Capacitance Between the Windings and the Magnetic Material Practical Approaches for Decreasing the Effects of Parasitic Capacitances References INDUCTOR DESIGN Air Coils and Related Shapes Inductor Shapes Typical Ferrite Inductor Shapes Fringing in Wire-Wound Inductors with Magnetic Cores Eddy Currents in Inductor Windings Foil Wound Inductors Inductor Types Depending on Application Design Examples of Different Types of Inductors Fringing Coefficients For Gapped-Wire-Wound Inductors Analitical Modeling of Combined Litz Wire-Full Wire Inductors References TRANSFORMER DESIGN Transformer Design in Power Electronics Magnetizing Inductance Leakage Inductance Using Parallel Wires and Litz Wires Interleaved Windings Superimposing Frequency Components Superimposing Modes References OPTIMAL COPPER/CORE LOSS RATIO IN MAGNETIC COMPONENTS Simplified Approach Loss Minimization in the General Case Loss Minimization Without Eddy Current Losses Loss Minimization Including Low-Frequency Eddy Current Losses Summary Examples References MEASUREMENTS Introduction Temperature Measurements Power Losses Measurements Measurement of Inductances Core Loss Measurements Measurement of Parasitic Capacitances Combined Measuring Instruments References APPENDIX A: RMS VALUES OF WAVEFORMS Definitions RMS Values of Some Basic Waveforms RMS Values of Common Waveforms APPENDIX B: MAGNETIC CORE DATA ETD Core Data (Economic Transformer Design Core) EE Core Data Planar EE Core Data ER Core Data UU Core Data Ring Core Data (Toroid Core) P Core Data (Pot Core) PQ Core Data RM Core Data APPENDIX C: COPPER WIRES DATA Round Wire Data American Wire Gauge Data Litz Wire Data APPENDIX D: MATHEMATICAL FUNCTIONS References INDEX

Method and apparatus of using magnetic material with residual magnetization in transient electromagnetic measurement

Abstract: A transmitter antenna assembly for transient electromagnetic well logging instrument comprises an antenna coil coupled with a current source and a magnetic core having residual magnetization. Switching current in the antenna coil results in magnetization reversal in the magnetic core and change in magnetic dipole moment of the antenna. After the magnetization reversal is complete the current is removed and the new vector of magnetic dipole of the antenna maintains constant (steady-state phase of the antenna dipole) due to magnetic hysteresis of magnetic material employed for the magnetic core. No power expenditure during the steady-state phase of the magnetic dipole facilitates highly effective generation and fast switching of a large magnetic dipole. The magnetic core also serves as a shield between the antenna coil and any conductive part of the antenna assembly. Embodiments suitable for measurement-while-drilling or measurements through casing make use of residual magnetization of magnetic drill collar or magnetic casing respectively.

Inductively coupled plasma processing apparatus

Abstract: An inductively coupled plasma processing apparatus (100) comprises a plasma chamber (12) with a dielectric window (400) forming a self-supporting wall element of the plasma chamber (12). The dielectric window (400) has an external and an internal side with respect to the chamber (12). An electromagnetic field source (140) is arranged in front of the external side of the dielectric window (400) for generating an electromagnetic field within the plasma chamber (12). The field source comprises at least one magnetic core (301, 302, 303). The at least one magnetic core (301, 302, 303) is attached to the external side of the dielectric window (400), such that the at least one magnetic core helps the dielectric window (400) to withstand collapsing forces caused by negative pressure inside said chamber during operation.

An equivalent instantaneous inductance-based technique for discrimination between inrush current and internal faults in power transformers

Abstract: A novel equivalent instantaneous inductance (EII)-based scheme is proposed to distinguish the inrush current from internal faults in power transformers, which is derived from the inherent difference of the magnetic permeability, due to the saturation and unsaturation, in the transformer iron core between the inrush current and an internal fault. First, the EII that represents these differences is defined, and its calculation methods and the criteria to identify the internal fault in the time and frequency domains are respectively developed. A total of 98 experimental cases are used to test the performance of the technique. In all of the tests, the inrush current is characterized by the drastic variation of the EII, but the EII of the faulty phase is kept almost constant. The experimental results verify the dependability, security, and fast operation of the proposed scheme. Besides, its easy implementation in real time is another advantage of the proposed method because of its simplicity.

Design method and material technologies for passives in printed circuit Board Embedded circuits

Abstract: The integration of passive components into the printed circuit board (PCB) as embedded passives integrated circuits (emPIC) results in a higher power density of power converters. To achieve a highly automated, low cost, integral manufacturing, the devices are constructed layer wise. Materials and processes necessary for the manufacturing of such circuits are described in this publication. Especially for magnetic components like inductors and transformers the design of such thin components is challenge. Because of the high aspect ratio, traditionally used models lead to a high calculation effort or use nonappropriate approximations. This contribution presents an analytic approach for the design. The model considers the magnetic flux distribution in the core and in the winding area and therefore allows a precise calculation of the inductivity as well as the losses in the device and their distribution. It is very well suited for a parametric analysis and thus for the synthesis of thin planar magnetic components. Material technologies for the construction of the capacitive layers and the magnetic cores are investigated. A ferrite polymer compound is adapted to be compatible with the PCB laminating process. Accordingly a 60-W offline converter was designed and fabricated using the new technology. Its transformer is entirely integrated in the PCB as well as 11 capacitors. Standard PCB lamination processes are used for the layerwise integration of the components. The circuit needs an area of the size of a credit card with a PCB thickness of 4 mm. Up to 82% efficiency could be demonstrated.

A planar inductor using Mn-Zn ferrite/polyimide composite thick film for low-Voltage and large-current DC-DC converter

Abstract: A new planar inductor using a composite magnetic core for low voltage and large current dc-dc converter has been developed The composite material consisted of a 40% volume fraction of Mn-Zn ferrite particle with a mean diameter of 10 /spl mu/m and polyimide matrix The composite magnetic core exhibited a low relative permeability of 6 The fabricated planar inductor with a size of 15/spl times/15/spl times/14 mm consisted of an inner two-turn copper square spiral coil, a top 350-/spl mu/m-thick composite magnetic core and a bottom 1-mm-thick Ni-Zn ferrite substrate The inductor had a dc coil resistance of 15 m/spl Omega/ and an inductance of 140 nH The degradation of inductance was below 4% at a superimposed dc current of 10 A A synchronous rectifier type buck converter with a switching frequency of 1 MHz, an input voltage of 5 V, and an output voltage of 1 V was constituted using a planar inductor, and exhibited a maximum conversion efficiency of 80% at 4 A

Boost converter utilizing bi-directional magnetic energy transfer of coupling inductor

Abstract: A boost converter utilizing bi-directional magnetic energy transfer of coupling inductor provides a high efficiency boost DC-DC converting with above 30 times voltage boost rate, which uses a coupling inductor and low voltage switch to absorb circuit induction voltage of a passive regenerative snubber no matter if switch is turned on or off. Such that, a much higher voltage boost rate than the turn rate of transformer and wider range of switching duty cycle is obtained. A bi-directional magnetic energy path is utilized, that is, when switch is turned on the first winding of coupling inductor stores magnetic excited high current energy, and opposite magnetic flux is induced on the second winding at the same time. When switch is turned off the magnetic excited current continues and increases the voltage on the second winding. The second winding has bi-directional magnetic current induced and fully utilizes capacity of transformer's iron core.

Antenna module-use magnetic core member, antenna module and portable information terminal provided with it

Abstract: There are provided an antenna module-use magnetic core member, an antenna module and a portable information terminal provided with the same, capable of improving a communication distance without increasing a module thickness. In an antenna module (1) in which a sheet-formed magnetic core member (4) is stacked on an antenna substrate (2) on which a looped antenna is formed, one having a performance index, expressed by µ' × Q, of 300 or higher when Q is a reciprocal of a loss factor (tan δ = µ"/µ') expressed by a real part µ' and an imaginary part µ" of a complex permeability at an applied frequency is used as the magnetic core member (4).

Arc fault detector

Abstract: An arc fault detector, as a stand alone device or in combination with a circuit interrupting device such as a ground fault interrupter (GFCI), protects from potentially dangerous arc fault conditions. The device utilizes a line side or load side series connected inductance having an air or magnetic core to generate the derivative di/dt signal of the arc current in the conductor. The derivative signal is fed to an arc fault detector where it is analyzed for the presence of arcing. The device can have two series connected inductors inductively coupled to each other such that the signal from one inductor is inductively coupled into the other inductor for coupling to the arc fault detector.

Antenna Module-Use Magnetic Core Member, Antenna Module, and Portable Information Terminal Having the Same

Abstract: There are provided an antenna module-use magnetic core member, an antenna module and a portable information terminal provided with the same, capable of improving a communication distance without increasing a module thickness. In an antenna module ( 1 ) in which a sheet-formed magnetic core member ( 4 ) is stacked on an antenna substrate ( 2 ) on which a looped antenna is formed, one having a performance index, expressed by μ′×Q, of 300 or higher when Q is a reciprocal of a loss factor (tan δ=μ″/μ′) expressed by a real part μ′ and an imaginary part μ″ of a complex permeability at an applied frequency is used as the magnetic core member ( 4 ).

Common mode choke coil

Abstract: PROBLEM TO BE SOLVED: To provide a common mode choke coil for interrupting a common mode noise current allowed to flow into from either one of an input terminal and an output terminal and passed to the other terminal over a wide frequency band. SOLUTION: Coils 3, 4 are wound around a low frequency closed magnetic path magnetic core 2 of MnZn group ferrite which is stored in a winding core cover 1 so as to cancel each other, and the winding end sides of both the coils 3, 4 are set on the end face before winding 5 to 30% of the regulated number of turns by superposing an insulting high frequency closed magnetic path magnetic core 5 of NiZn group ferrite or the like. After the superposed setting, the remainder of the regulated number of turns, i.e. the winding end sides of both the coils 3, 4, are wound to complete the common mode choke coil. Or, after winding the coils 3, 4 around the MnZn group ferrite closed magnetic path magnetic core 2 so as to cancel each other, the coils 3, 4 are further wound around the NiZn group ferrite closed magnetic path magnetic core 2 so as to canceled each other so that the winding ends are connected in series to obtain integrated structure of both the coils. COPYRIGHT: (C)2005,JPO&NCIPI

Method of manufacturing laminated core

Abstract: A method of manufacturing a laminated stator core includes: forming a band-shaped yoke core piece having a shape that a yoke of the laminated stator core is developed in a straight line and having concave connection portions in the inner circumferential edge thereof by punching a metal plate; forming a laminated yoke body by winding and laminating the band-shaped yoke core piece in a spiral shape and coupling the laminated band-shaped yoke core piece in a caulking manner; forming a magnetic core piece having a convex connection portion at the base end thereof by punching a metal plate; forming a laminated magnetic body by laminating and coupling a predetermined number of the magnetic core pieces to each other in a caulking manner; and coupling the laminated yoke body and the laminated magnetic body to each other by winding a coil around the laminated magnetic body and then inserting the convex connection portions into the concave connection portions.

Magnetizing inrush model of transformers based on structure parameters

Abstract: This paper proposes a circuit model for the transient period of inrush current in a transformer. The magnetizing inrush model is developed from the structural parameters of the transformer. In the analysis of the magnetization curve, the relationship between the magnetic flux density and magnetic field intensity differs from the ordinary B-H curve; this paper interchanges the B and the H and characterizes the B-H of the magnetic core as a simple tangent function in the H-B planes. Furthermore, the concept of inrush equivalent inductance is also used in the magnetizing inrush model. Using the magnetizing inrush model, an inrush current value can be estimated before the transformer is manufactured. Moreover, in the future, this model can provide the power system with a more thorough transient analysis. During this research, the inrush currents are simulated using the circuit model from ICAP/4. Fourteen actual transformers, each with a different winding structure, are used for demonstration. Experiments and simulations are carried out to examine the proposed method.

Radio-frequency planar integrated inductor with Permalloy-SiO/sub 2/ granular films

Abstract: We have designed and fabricated a radio-frequency (RF) planar integrated inductor using Permalloy-SiO/sub 2/ granular film as the magnetic core. By controlling the composition and microstructure, we produced a granular film with excellent soft magnetic properties and high electrical resistivity. The inductance L of the inductor with granular Permalloy-SiO/sub 2/ magnetic film increased 6% to 15%, compared to that of an air-core inductor, and the quality factor Q value was high, approaching 10 in the frequency range of 2-3 GHz. The controllable anisotropy of the granular film generated in deposition process gives the magnetic inductor a very high self-resonance frequency peak-over 6 GHz.

Integration of crossed anisotropy magnetic core into toroidal thin-film inductors

Abstract: A new approach to RF thin-film inductors with an integrated magnetic core has been investigated. A toroidal inductor design was realized in thin-film technology aiming at small-signal applications in the frequency range from 10 MHz to 1 GHz. The magnetic core consists of a multilayer of sputter deposited soft magnetic FeCoBSi. The individual magnetic films were deposited in a way to realize a crossed magnetic anisotropy in the core. High-frequency measurements of the multilayers already illustrated the advantages of the unique magnetic geometry. The influence and benefit of such a magnetic core on the toroid microinductor is discussed. The results show that such crossed anisotropy microinductors are a very promising alternative to common planar spiral inductors in the RF range.

High frequency electric motor or generator

Abstract: A device such as an electric motor, an electric generator, and a regenerative electric motor includes at least one independent energizable electromagnetic assembly. Each independent electromagnetic assembly has an associated one-piece magnetic core. Each independent electromagnetic assembly defines two stator poles. Each one-piece magnetic core provides the entire magnetic return path for the two magnetic stator poles associated with each independent electromagnetic assembly.

An iron core probe based inter-laminar core fault detection technique for generator stator cores

Abstract: A new technique for detecting incipient inter-laminar insulation failure of laminated stator cores of large generators is proposed in this paper. The proposed scheme is a low flux induction method that employs a novel probe for core testing. The new probe configuration, which uses magnetic material and is scanned in the wedge depression area, significantly improves the sensitivity of fault detection as well as user convenience compared to existing methods. Experimental results from various test generators tested in factory, field, and lab environments under a number of fault conditions are presented to verify the sensitivity and reliability of the proposed scheme.

High precision current sensor

Abstract: A current sensor for measuring a current flowing through a Strombusschiene (12) electric current comprises: a magnetic core (20) having an opening through which the Strombusschiene (12) with a certain distance therefrom; and a first magnetic sensor (14) for detecting a magnetic flux in the magnetic core (20), wherein the magnetic flux generated by the current flowing from the Strombusschiene (12) current. The magnetic core (20) has a first gap (Ga1) and a second gap (Gb1). The first magnetic sensor (14) is arranged in the first gap (Ga1). The second gap (Gb1) is to prevent able to magnetic saturation of the magnetic core (20).

Numerical simulation and test of a UV-LIGA-fabricated electromagnetic micro-relay for power applications

Abstract: The research work presented in this paper focused on the modeling, simulation, and test of the dynamic performances of a UV-LIGA-fabricated electromagnetic power relay. The relay consists of a microfabricated magnetic core, a spring-suspended Ni–Fe plunger, and a mechanically wound solenoid. The performances of the prototype relay are consistent with those predicted using mathematical models. The current capacity of the prototype relay with a plunger thickness of 17 μm was measured to be over 300 mA. Switching currents over 100 mA have been applied to the electromagnetic without overheat related failure. The maximum square wave frequency tested for the prototype relay was measured as 500 Hz. The flexibility of the design and the UV-LIGA fabrication technology used make the scale-up of the power capacity possible if needed. The current capacity of the relay may be further boasted by optimal design of the suspension spring and the magnetic core that serve as part of the electrical circuit. The moderate current capacity was the result of the manual assembly, and can be improved with wire-bonding technology and adoption of coils from commercial vendors.

Magnetic properties of electroplated nano/microgranular NiFe thin films for rf application

Abstract: A granular NiFe thin film with large in-plane magnetic anisotropy and high ferromagnetic-resonance frequency developed for radio-frequency integrated circuit (IC) applications is presented. During the deposition, three-dimensional (3D) growth occurs, yielding NiFe grains (? ? 1.0??m). Nanonuclei (? ? 30–50?nm) are observed in single NiFe grains by atomic-force microscopy (AFM). The in-plane magnetic anisotropy is estimated to be ? 50?mT. The frequency-dependent complex permeability is extracted. By taking the NiFe film as a magnetic core, solenoid-type inductors are fabricated and demonstrated and show a high operating frequency ( ? 5.5?GHz) with a maximum quality factor ( ? 3).

Fuel injection device

Abstract: A method of controlling a fuel injection device that can control a small amount of injection is provided. A fuel injection device for use in an internal combustion engine, includes: a valve body that can open and close a fuel passage, a needle that transfers a force with the valve body, and executes valve opening/closing operation, and an electromagnet that includes a coil and a magnetic core provided as a driver for driving the needle, and a cylindrical nozzle holder disposed on an outer periphery of the magnetic core and the needle, in which a current is supplied to the coil to exert a magnetic attractive force between the magnetic core and the needle to open the valve body.

Dust core and its manufacturing method

Abstract: A dust core formed by press-forming a magnetic core powder produced by coating magnetic powder containing Fe as a main component with an insulating film. The dust core is characterized in that the magnetic powder contains 1.5 mass% or less of Si, the volume average particle size is 80 to 300 μm, the density ratio is 96% or more, and the dust core is used in an alternating magnetic field of a frequency of 100 to 2,000 Hz. The dust core exhibits a low iron loss and high magnetic flux density equivalent or superior to those of conventionally used magnetic steel sheets when the dust core is used at such a frequency.

Airgap fringing flux reduction in inductors using open-circuit copper screens

Abstract: In a gapped inductor, airgap fringing flux induces eddy currents in coil conductors in the vicinity of the airgap, producing unwanted power loss and heat in the coil. An open-circuit copper screen placed around the airgap of a ferrite core is shown to reduce the fringing flux around the airgap. The reduction in fringing flux is shown by experiment to reduce the power loss, in the inductor winding, associated with eddy currents induced by airgap fringing flux, and practical results compare favourably with presented finite-element results. The reduction in coil losses reduces the cooling requirement for the inductor, or alternatively, allows an increase in the thermal rating of the inductor.

Inductively coupled plasmas: Optimizing the inductive-coupling efficiency for large-area source design

Abstract: An inductively coupled plasma (ICP) source enabling high-density plasma generation was developed for large area processing. Technological difficulties related to the scaling up of the coil antenna, dielectric vacuum window, and gas distribution have been addressed. The proposed solution consists in using a magnetic core to concentrate the magnetic field produced by the antenna. Both are placed within the plasma chamber, and the gas injection is done through the magnetic pole. A 75×72-cm2 plasma source has been designed based on this solution. First, the electrical operation and coil geometries were optimized. The results show that the use of a low excitation frequency (2MHz) increases the electrical efficiency of the magnetic core, enabling a higher plasma-density generation than at the classical radio frequency of 13.56MHz. The antenna configuration providing the better uniformity is composed of three loops connected in parallel. Some tuning inductances in series with each loop were added to balance the ...

Ferromagnetic RF Integrated Inductor with Closed Magnetic Circuit Structure

Abstract: Closed magnetic circuit type ferromagnetic RF integrated inductors have been fabricated based on MEMS-like micro fabrication techniques. The taper etching process greatly helped to endure sufficient magnetic flux flow at the edge of the top and bottom magnetic layers. Air cores and three different sandwich type ferromagnetic inductos are also microfabricated. Measured results exhibited the quality factor Q=12, being highest among the published data of ferromagnetic RF integrated inductor at 1 GHz.

Operational characteristics of linear synchronous actuator with field-cooled HTS bulk secondary

Abstract: It is expected that HTS bulk materials will be applied to various electric devices. We have fabricated and tested a linear synchronous actuator with double-sided primary and HTS bulk secondary. The linear actuator consists of a field-cooled YBCO bulk for secondary (mover) and copper windings with iron core as a primary. The primary, which was excited by a three-phase VVVF power source to generate sinusoidal traveling magnetic field, was divided into two sections: 1) the starting section in which the secondary is accelerated as an induction machine; and 2) the synchronous section in which the secondary moves with a specified synchronous speed. As the secondary, two field-cooled bulks were arranged in certain interval. In this paper, for various intervals of bulks, we experimentally investigated the static characteristic in points of synchronous thrust force and the pull-in characteristics. And we developed a simulation program based on the finite element method (FEM) to investigate electromagnetic behavior within the bulk exposed to the magnetic field generated by the primary winding. We investigated the influence of the size, the number, and the interval of bulks on the static characteristic in points of synchronous thrust force by using the developed computer program.

A leakage-inductance-based ZVS two-inductor boost converter with integrated magnetics

Abstract: A two-inductor boost converter topology has conduction loss and transformer utilization advantages in converting low-voltage higher current inputs to high output voltages. In this letter, a new zero-voltage switching (ZVS) two-inductor boost converter with integrated magnetics is proposed. In the new topology, the two current source inductors, a resonant inductor and a two-winding transformer, are integrated into one single magnetic core with three windings. Two windings simultaneously perform the functions of the current source inductors and the transformer primary. The transformer leakage inductance forms the resonant inductance. This leads to a much more compact converter design with a significant reduction in the number of core and winding components. A theoretical analysis establishes the operating point of the ZVS converter. Both of the theoretical and experimental waveforms, including flux waveforms for the legs of the integrated core structure, are presented at the end of the letter.

Fluid cooling for iron core and winding packs

Abstract: A power choke or transformer has an iron core, windings, and a cooling apparatus having a heat exchanger with a heat absorber and a cooling fluid duct operationally connected to the heat absorber, wherein the iron core is operationally connected to the heat absorber to remove heat emitted by the iron core.

Soft Magnetic Material, Compressed Powder Magnetic Core and Method for Producing Compressed Powder Magnetic Core

Abstract: A soft magnetic material has an iron based powder that has an insulating coating on the surface and an ester wax. The ester wax is added in an amount not less than 0.02% by weight and not more than 0.6% by weight in relation to the soft magnetic material. Consequently, seizure between a metal mold and a material to be molded at the time of molding can be suppressed and the arising of a black residue can be prevented.