JP2019050411A - Magnetic material core and coil device - Google Patents

Abstract

To provide a magnetic material core on which a terminal electrode is easily formed and a coil device including the magnetic material core.SOLUTION: A magnetic material core 2 includes a metal particle 30 insulated by an insulation phase 32. An electrode scheduled part 20 in which the insulation phase 32 is removed at only part of the surface of the magnetic material core 2 and the surface of the metal particle 30 is exposed in a region having predetermined area is formed. Terminal electrodes 24, 26 are formed at the electrode scheduled part 20.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a magnetic body core in which terminal electrodes can be easily formed, and a coil device having the magnetic body core.

  In order to form a terminal electrode (for example, an Ag electrode film) on a magnetic core used in a coil device etc., first, Ag powder and glass frit are applied to the electrode planned portion of the magnetic core and heat treated (fired) to form a base The electrodes are formed and then Ni and Sn plated.

  Alternatively, as shown in Patent Document 1 below, a solder paste is applied to the base electrode to form a terminal electrode. In any case, it is necessary to form a base electrode by applying Ag powder and glass frit and performing heat treatment (baking), which causes a problem that the process becomes complicated and the workability is poor. Moreover, in order to form a base electrode by such a method, a part of glass frit will exist on the surface, and there also exists a subject that plating may be difficult.

JP, 2013-45928, A

  The present invention has been made in view of such an actual situation, and an object thereof is to provide a magnetic body core in which the formation of a terminal electrode is easy, and a coil device having the magnetic body core.

In order to achieve the above object, the magnetic core according to the present invention is
A magnetic core in which metal particles are insulated in an insulating phase,
An electrode planned portion in which the insulating phase is removed and the surface of the metal particle is exposed in a predetermined area area is formed only on a part of the surface of the magnetic core, and a terminal is formed on the electrode planned portion. It is characterized in that an electrode is formed.

  In the magnetic core according to the present invention, it is not necessary to form a base electrode by applying a metal powder such as Ag and a glass frit and performing heat treatment (baking). Instead, the insulating phase is removed and the surface of the metal particles is removed only by performing chemical treatment such as applying a chemical on only a part of the surface of the magnetic core or physical treatment such as vacuum plasma treatment. An exposed electrode portion is formed.

  In the electrode planned portion, since the insulating phase is removed and the surface of the metal particle is exposed, plating can be performed on the surface, and the terminal electrode can be easily formed by plating. Further, in the present invention, since the glass frit is not used, a part of the glass frit is not present on the surface, and plating can be performed easily and reliably. In addition, it is also easy to form a solder film instead of plating on the electrode planned portion of the present invention. In the present invention, the terminal electrode can be composed of a plated film or a solder film.

  In the present invention, the method of forming the electrode scheduled portion is not particularly limited, but preferably a chemical treatment such as applying a chemical or a physical treatment such as vacuum plasma treatment is performed on a part of the surface of the magnetic core.

  The insulating phase may be an inorganic insulating coating formed on the surface of the metal particles, or a synthetic resin in which the metal particles are dispersed.

Preferably, the magnetic core is
A winding core on which a wire is wound;
A ridge portion located at an end in the axial direction of the winding core portion is integrally formed,
The said electrode plan part is formed in the said collar part.

  For example, at least one end of the wire is connected to the terminal electrode.

The coil device according to the present invention is
It has a magnetic body core described above, and a wire wound around the winding core.

FIG. 1A is a partially cutaway perspective view of a coil device according to an embodiment of the present invention. FIG. 1B is a partially cutaway perspective view of a coil device according to another embodiment of the present invention. FIG. 2 is a perspective view of the coil device shown in FIG. 1A as viewed from the bottom side. FIGS. 3A to 3C are schematic cross-sectional views showing a method of manufacturing the terminal electrode shown in FIG. 1A. FIG. 4 is a perspective view of a magnetic core showing a manufacturing process of a coil device according to another embodiment of the present invention. FIG. 5A shows a process subsequent to FIG. 4 and is a perspective view showing a modification of the electrode scheduled portion. FIG. 5B is a perspective view showing a modification of FIG. 5A. FIG. 6A is a perspective view showing the manufacturing process of the coil device, showing the process following FIG. 5 (A). 6B is a perspective view showing a manufacturing process of the coil device, showing a manufacturing process different from FIG. 6A, and showing a process subsequent to FIG. 5 (A). FIG. 7A is a perspective view of a coil device according to another embodiment of the present invention showing the process subsequent to FIG. 6A. FIG. 7B is a perspective view of a coil device according to still another embodiment of the present invention, showing a step subsequent to FIG. 6B. FIG. 8A is a cross-sectional perspective view taken along the line VIIIA-VIIIA shown in FIG. 7A. FIG. 8B is a cross-sectional perspective view taken along the line VIIIB-VIIIB shown in FIG. 7B.

  Hereinafter, the present invention will be described based on embodiments shown in the drawings.

First Embodiment As shown in FIGS. 1A and 2, a coil device 1 according to an embodiment of the present invention has a magnetic core 2. The magnetic core 2 has a winding core 4 around which the wire 12 is wound, and ridges 6 and 8 respectively located at both ends in the axial direction (Z-axis direction) of the winding core 4. Is integrally molded.

  In the present embodiment, the winding core 4 has a cylindrical shape, around which the wire 12 is wound in a single layer or a plurality of layers to constitute the coil unit 10. However, the winding core 4 is not limited to a cylindrical shape, and may have an elliptical cylindrical shape, a rectangular cylindrical shape, or any other shape. In addition, although the flanges 6 and 8 have a rectangular plate shape in the present embodiment, any shape may be used as long as it is a polygonal plate shape, a disc shape, an elliptical plate shape, or any other shape having a size larger than that of the winding core 4 It may be of such a shape.

  The ridges 6 and 8 do not necessarily have the same shape as each other, but in the present embodiment, they have the same shape. The size of the coil device 1 is not particularly limited, but the length (X-axis direction) is 0.4 to 20 mm, the width (Y-axis direction) is 0.2 to 20 mm, and the height (Z-axis direction) is It is 0.2-15 mm. The X axis, the Y axis and the Z axis are perpendicular to one another.

  In the present embodiment, the terminal electrode 24 and the terminal electrode 24 are insulated by a predetermined distance on both sides in the X-axis direction on the back surface 8a of the ridge 8 on the side on which the coil device 1 is mounted among the two ridges 6 and 8. 26 are formed. The terminal electrode 24 is continuously formed at both ends in the Y-axis direction of the electrode main body 24a fixed to the back surface 8a of the collar portion 8 and in the Y-axis direction of the electrode main body 24a. And an auxiliary electrode piece 24b fixed to the side surfaces 8b and 8c.

  Similar to the terminal electrode 24, the terminal electrode 26 is continuously formed on both ends of the electrode body 26 a fixed to the back surface 8 a of the collar 8 and in the Y-axis direction of the electrode main body 26 a. And the auxiliary electrode piece 26b fixed to the side surfaces 8b and 8c opposite to each other in the Y-axis direction. Both ends 12a and 12b of the wire 12 wound around the coil portion 10 are respectively attached to the auxiliary electrode pieces 24b and 26b formed on one side surface 8b in the Y axis direction by laser welding, resistance welding, soldering or the like. It is connected. The ends 12 a and 12 b of the wire 12 may be directly connected to the electrode bodies 24 a and 26 a fixed to the back surface 8 a of the collar 8.

  In the present embodiment, the wire 12 is not particularly limited, and may be a single wire or a stranded wire, and examples of the material thereof include copper, silver, gold, or an alloy of these. Further, the cross section of the wire 12 is not limited to a circle, but may be a flat cross section as shown in FIG. 1B. It is preferable that these wires 12 be coated with insulation at portions other than the both ends 12a and 12b connected to the auxiliary electrode pieces 24b and 26b. Although the wire 12 is edgewise wound around the winding core 4 in FIG. 1B, the wire 12 may be wound in a crosswise manner.

  In the present embodiment, as shown in FIG. 3A, the magnetic core 2 has a fine structure in which a large number of metal particles 30 are mutually insulated by an inorganic insulating film 32 as an insulating phase. The metal particles 30 are not particularly limited as long as they are magnetic metals, and for example, Fe-Ni alloy powder, Fe-Si alloy powder, Fe-Si-Cr alloy powder, Fe-Si-Al alloy powder, permalloy powder, Amorphous powder, Fe powder, etc. are illustrated. These ferromagnetic metal powders are preferable because they have a higher saturation magnetic flux density than ferrite powders, and direct current superposition characteristics are maintained up to a high magnetic field.

  The inorganic insulating film 32 is made of, for example, a silicon oxide film, a metal oxide film, a glass film or the like. The particle size of the metal particles 30 is not particularly limited, but preferably the average particle size is 0.5 to 100 μm. Although the film thickness of the inorganic insulating film 32 is not particularly limited, it is preferably 1/1000 to 1/10 of the particle diameter of the metal particles 30. The metal particles 30 themselves have conductivity, but the metal particles 30 are insulated from each other by the insulating film 32, and the entire magnetic core 2 can be said to be an insulator.

  The magnetic body core 2 of the present embodiment is a sintered body, and is obtained by pressing and shaping granulated powder containing the metal particles 30 into a predetermined shape in a mold. The molding method is not limited to the present embodiment. For example, injection molding, extrusion molding, lamination molding, transfer molding and the like are exemplified. By firing the core compact before firing, for example, at 600 to 1100 ° C., the fired magnetic core 2 can be obtained.

  The method of forming the terminal electrodes 24 and 26 on the magnetic core 2 shown in FIGS. 1A and 1B will now be described.

  Chemical treatment is performed on the surface of the core 2 only for the electrode planned portion 20 of the magnetic core 2 in which the terminal electrodes 24 and 26 are formed. In this chemical treatment, only the surface of the magnetic core 2 corresponding to the electrode planned portion 20 is exposed, and the surface of the other portion of the core 2 is masked with a resist film (removed after chemical treatment) or the like. In that state, only the surface of the magnetic core 2 corresponding to the electrode planned portion 20 is dipped in a drug within the range of a predetermined area corresponding to the electrode planned portion 20. As a chemical | medical agent, the chemical | medical agent which dissolves and removes the insulation film 32 is preferable.

  For example, when the insulating film 32 is a silicon oxide film, hydrofluoric acid, chemical conversion soda, or the like is used as the chemical. When the insulating film 32 is a (metal oxide film), an oxide film remover, nitric acid, sulfuric acid, hydrochloric acid, ammonia or the like is used as the chemical.

  As a condition for immersing the surface of the magnetic core 2 corresponding to the electrode planned portion 20 in a drug, as shown in FIG. 3B, the surface of the metal particle 30 is on the surface of the core 2 corresponding to the electrode planned portion 20 The conditions are such that the metal particles 30 which are exposed and located on the final surface after the treatment do not come off the surface. In order to prevent the metal particles 30 from falling off from the surface, it is preferable that the metal particles be exposed only on the outer surface of the metal particles 30 and the insulating coating 32 not be removed on the inner surface of the metal particles 30.

  The method for realizing the surface state as shown in FIG. 3 (B) is not limited to the chemical immersion treatment. For example, physical processing such as vacuum plasma processing may be used.

  As another method for realizing the surface state as shown in FIG. 3 (B), sandblasting and the like are exemplified.

  Next, in the present embodiment, as shown in FIG. 3C, the surface of the electrode planned portion 20 where the insulating coating 32 is removed and the surface of the metal particle 30 is exposed is subjected to electrolytic plating or electroless plating. A desired plating film is deposited to form terminal electrodes 24 and 26 having a predetermined thickness. The plating film may be a single layer or a multilayer, and for example, a plating film such as Ni-Sn plating, Cu-Ni-Sn plating, Sn plating, Ni-Au plating, Au plating, etc. is formed. The thickness of the terminal electrodes 24 and 26 is not particularly limited, but preferably 0.1 to 15 μm.

  In the magnetic core 2 according to the present embodiment, it is not necessary to form a base electrode by applying a metal powder such as Ag and a glass frit and performing heat treatment (baking). Instead, for example, only by chemically treating or physically treating only a part of the surface of the magnetic core 2 (the electrode planned portion 20), the insulating coating 32 is removed and the surface of the metal particle 30 is exposed. The planned portion 20 is formed.

  In the electrode planned portion 20, since the insulating coating 32 is removed and the surface of the metal particle 30 is exposed, plating on the surface is easy, and the terminal electrodes 24 and 26 can be easily formed by plating. it can. Further, in the present embodiment, since the glass frit is not used, a part of the glass frit is not present on the surface, and the plating can be performed easily and reliably. Further, in the present embodiment, since it is not necessary to form a base electrode by applying a metal powder such as Ag and a glass frit and performing a heat treatment (baking), it contributes to a reduction in manufacturing cost.

  In the present embodiment, the terminal electrodes 24 and 26 may be formed by forming a solder film instead of plating at the electrode planned portion 20. In order to form a solder film, as shown in FIG. 3 (B) and FIG. 3 (C), the insulating coating 32 is removed and the surface 20 of the electrode planned portion where the surface of the metal particle 30 is exposed is selected. Then, a solder film is formed to obtain terminal electrodes 24 and 26. When forming the solder film, after applying the flux, the solder film may be formed by dipping to form the terminal electrodes 24 and 26.

  In this case, since no plating process is required, the workability is further improved, and the manufacturing cost is also reduced. Furthermore, by not performing the plating process, it is possible to effectively prevent IR deterioration due to the remaining plating solution.

  In the above-described embodiment, the terminal electrodes 24 and 26 are formed not only on the bottom surface 8a of the flange 8 but also on the side surfaces 8b and 8c, but the terminal electrodes 24 and 26 may be formed on only one of them. good. Further, the positions at which the terminal electrodes 24 and 26 are formed are not particularly limited.

Second Embodiment The present embodiment is the same as the first embodiment, except as described below, and exhibits the same functions and effects.

  In the present embodiment, the magnetic core 2 is not a sintered body, but is formed of a compact obtained by compacting and contains a synthetic resin. At the time of compacting, molten synthetic resin in which metal particles are dispersed is poured into the inside of a mold, and the synthetic resin is cured by heat, for example. In that case, the magnetic core 2 is made of a synthetic resin in which the metal particles 30 are dispersed, and the synthetic resin becomes an insulating phase. As a synthetic resin used for powder compacting, an epoxy resin, a urethane resin, an acrylic resin, a diallyl phthalate resin, a silicone resin, a polyimide amide resin, a polyimide resin, a PVA resin etc. are illustrated, for example.

  In this embodiment, for example, when the synthetic resin is an epoxy resin, toluene, xylene, sulfuric acid, nitric acid or the like is used as a chemical for dissolving and removing the synthetic resin present on the surface of the metal particles 30.

  As a condition for immersing the surface of the magnetic core 2 corresponding to the electrode planned portion 20 in a chemical, the surface of the metal particle 30 is exposed on the surface of the core 2 corresponding to the electrode planned portion 20, and on the final surface after treatment. The conditions are such that the metal particles 30 located do not come off the surface. In order to prevent the metal particles 30 from falling off the surface, the metal particles are exposed only on the outer surface of the metal particles 30, and the synthetic resin as the insulating phase is not removed on the inner surface of the metal particles 30. Is preferred.

  The method for realizing such a surface state is not limited to the chemical immersion treatment. For example, physical processing such as vacuum plasma processing may be used. Preferred conditions for vacuum plasma treatment for removing the synthetic resin on the surface of the metal particles 30 are preferably the same as the conditions for removing the inorganic insulating film in the first embodiment.

Third Embodiment The coil device according to the second embodiment of the present invention is the same as the coil device 1 of the first embodiment except for the following, and exhibits the same function and effect. That is, in the present embodiment, as shown in FIG. 4 and FIG. 5A and FIG. 5B, on the back surface 8a of the ridge portion 8, a pair extending along the X-axis direction with a distance in the Y-axis direction. Grooves 8a1 are formed.

  The grooves 8a1 are portions which are recessed and processed by grinding, polishing or cutting from the back surface 8a of the magnetic core 2, and as shown in FIG. 5A, the frame portions 8a2 are provided outside the respective grooves 8a1 in the X axis direction. It may remain or, as shown in FIG. 5B, the frame 8a2 may be removed.

  The depth of each groove 8a1 in the Z-axis direction is not particularly limited, but is preferably smaller than the thickness t0 of the ridge portion 8 in the Z-axis direction, and preferably 1/2 or less of t0. From the viewpoint of reducing the height of the coil device 1 in the Z-axis direction, the groove depth of the groove 8a1 is such that at least a part (preferably all) of the groove 8a1 can fit inside the terminal electrodes 24 and 26. preferable. By forming the groove 8a1 by grinding, polishing or cutting, the electrode planned portion 20 is formed in that portion, as in the first embodiment. If it is not necessary to reduce the height of the coil device 1 in the Z-axis direction, the electrode scheduled portion 20 may be formed by grinding or polishing the corresponding surface without forming the groove 8a1.

  As shown in FIG. 6A, each end 12a, 12b of the wire 12 may be inserted into the electrode scheduled portion 20 of each groove 8a1 as shown in FIG. 6A, but as shown in FIG. 6B Alternatively, the solders 24A and 26A may be selectively attached to the electrode planned portions 20 of the grooves 8a1 before the wire 12 is wound.

  As shown in FIG. 6A, in the case where each end 12a, 12b of the wire 12 is to be inserted after being wound by the wire 12, it is thereafter positioned in each groove 8a1, as shown in FIG. 7A. Solder is attached to the electrode planned portion 20 of each groove 8a1 so as to cover each end 12a, 12b of the wire 12, and the terminal electrodes 24, 26 are formed. In that case, as shown in FIG. 8A, each end 12a, 12b of the wire 12 covered with the terminal electrodes 24, 26 made of solder is in close contact with the bottom surface of each groove 8a1.

  As shown in FIG. 6B, when the solders 24A and 26A are selectively attached to the electrode planned portions 20 of each groove 8a1 before winding by the wire 12, as shown in FIG. 6A. Winding with wire 12 is made. Thereafter, each end 12a, 12b of the wire 12 is soldered again so as to be embedded inside the solders 24A and 24B shown in FIG. 6B, and as shown in FIG. 7B, the terminal electrodes 24 and 26 made of solder. It is embedded inside. In this case, as shown in FIG. 8B, a gap is formed between each end 12a, 12b of the wire 12 covered by the terminal electrodes 24, 26, and the bottom of each groove 8a1, and the solder intervenes therebetween. become.

  The present invention is not limited to the above-described embodiment, and can be variously modified within the scope of the present invention.

  For example, in the embodiment described above, the outer periphery of the coil portion 10 may be filled with a magnetic powder containing synthetic resin in the gap between the ridges 6 and 8. In that case, the inductance of the coil device is improved.

  Hereinafter, the present invention will be described based on further detailed examples, but the present invention is not limited to these examples.

Example 1
The granulated powder containing the metal particles 30 was filled in a mold and pressed to obtain a core molded body before firing. The magnetic core 2 after firing was obtained by firing the core compact before firing at 600 to 850 ° C. Only a part of the surface of the magnetic core 2 was chemically treated under the conditions of 5% diluted sulfuric acid solution for 5 minutes by a chemical immersion method. A plated film was formed on the surface under the conditions of barrel plating Ni-Sn two-layer plating to obtain a terminal electrode. It was confirmed that the plating film was formed only on the chemical immersion surface of the core 2. The total film thickness of the plating film was 8 μm. The inorganic insulating film 32 of the metal particles 30 was a silicon oxide film, and the chemical for removal was sulfuric acid.

Example 2
In Example 1, terminal electrodes were formed in the same manner as in Examples 1 and 2 except that a solder coating was formed by dipping in a solder solution without plating. It was confirmed that the solder film was formed only on the chemically treated surface of the core 2. The film thickness of the solder film was 20 μm.

DESCRIPTION OF SYMBOLS 1 ... Coil apparatus 2 ... Magnetic material core 4 ... Winding core part 6, 8 ... Ridge part 8a1 ... Groove 8a2 ... Frame part 10 ... Coil part 12 ... Wire 20 ... Electrode planned part 24, 26 ... Terminal electrode 24A, 26A ... Solder 30 ... Metal particle 30a ... Extension in the planar direction of metal particle 32 ... Insulation coating

Claims (7)

A magnetic core in which metal particles are insulated in an insulating phase,
The magnetic core is made of a sintered body,
The insulating phase is an inorganic insulating coating formed on the surface of the metal particles,
The inorganic insulating film is removed only at a part of the surface of the magnetic core, and an electrode planned portion in which only the outer surface of the adjacent metal particle is exposed in a predetermined area region is formed.
A magnetic core in which a terminal electrode is formed at the electrode planned portion.   The magnetic core according to claim 1, wherein the terminal electrode is a plated film or a solder film.   The magnetic body core according to claim 1 or 2, wherein the electrode planned portion is formed by performing chemical treatment or physical treatment on a part of the surface of the magnetic body core.   The magnetic core according to any one of claims 1 to 3, wherein the inorganic insulating film is a silicon oxide film or a metal oxide film. In the magnetic core,
A winding core on which a wire is wound;
A ridge portion located at an end in the axial direction of the winding core portion is integrally formed,
The magnetic body core according to any one of claims 1 to 4, wherein the electrode planned portion is formed in the ridge portion.   The magnetic core according to claim 5, wherein at least one end of the wire is connected to the terminal electrode. A magnetic core according to claim 5 or 6,
A coil device having a wire wound around the winding core.

Images