WO2010064505A1

WO2010064505A1 - Electronic component

Info

Publication number: WO2010064505A1
Application number: PCT/JP2009/068382
Authority: WO
Inventors: 秀二木原; 治松本; 勝之内田
Original assignee: 株式会社村田製作所
Priority date: 2008-12-03
Filing date: 2009-10-27
Publication date: 2010-06-10
Also published as: CN102232233A; JPWO2010064505A1; JP5327231B2

Abstract

Provided is an electronic component that has direct current superposition characteristics such that a large inductance value can be obtained when a relatively low direct current is flowing in a coil and such that the inductance value does not drop abruptly even when a relatively high direct current is flowing in the coil. A laminate (12a) is created by lamination of magnetic layers (16a-16k). A coil (L) is built into the laminate (12a) and has a coil axis (X) that extends in the z-axis direction. The magnetic permeability of the laminate (12a) is lower than that of the magnetic layers (16a-16k), and further includes a nonmagnetic layer (17), which is laminated with the magnetic layers (16a-16k) to intersect the coil axis (X), and a high magnetic permeability part (19) that has magnetic permeability higher than that of the magnetic layers (16a-16k) and is provided to penetrate through the nonmagnetic layer (17) inside the coil (L).

Description

Electronic components

The present invention relates to an electronic component, and more particularly, to an electronic component having a coil incorporated in a laminated body.

As a conventional electronic component incorporating a coil, for example, a multilayer inductor described in Patent Document 1 is known. In the multilayer inductor, a coil composed of a plurality of coil patterns is incorporated in a multilayer body composed of magnetic layers. The nonmagnetic layer is provided so as to intersect the coil axis inside the coil.

According to the multilayer inductor, since the nonmagnetic material layer is provided, the magnetic flux density in the multilayer body is reduced. As a result, even if the direct current flowing through the multilayer inductor is increased, magnetic saturation is less likely to occur in the multilayer body, and a sudden decrease in inductance value due to magnetic saturation is less likely to occur. That is, the DC superimposition characteristic of the multilayer inductor is improved.

Incidentally, the multilayer inductor described in Patent Document 1 may be used in, for example, a DC-DC converter in an electronic device such as a mobile phone. In such a multilayer inductor, when a relatively small DC current flows through the coil, a large inductance value can be obtained, and even if a relatively large DC current flows through the coil, the inductance value does not rapidly decrease. DC superposition characteristics are required.

However, in the multilayer inductor described in Patent Document 1, it is difficult to obtain a large inductance value when a relatively small DC current flows through the coil. More specifically, in the multilayer inductor, a nonmagnetic material layer is provided in the coil. This suppresses the occurrence of magnetic saturation in the stack. Therefore, even if a relatively large direct current flows through the coil, the inductance value is suppressed from rapidly decreasing. On the other hand, the nonmagnetic material layer reduces the magnetic flux density in the stacked body. For this reason, the non-magnetic layer prevents the multilayer inductor from generating a large inductance value when a relatively small direct current flows through the coil.

JP 2006-216916 A

Therefore, an object of the present invention is to obtain a large inductance value when a relatively small DC current flows through the coil, and the inductance value rapidly decreases even when a relatively large DC current flows through the coil. It is to provide an electronic component having a direct current superimposition characteristic.

An electronic component according to an aspect of the present invention includes a laminated body in which a plurality of first insulator layers are laminated, and a coil having a coil shaft that is built in the laminated body and extends in the laminating direction. And the laminate has a lower magnetic permeability than the first insulator layer, and is provided in the laminate so as to intersect the coil axis. And a high magnetic permeability that is higher than that of the first insulator layer and that is provided on each of the upper side and the lower side in the stacking direction of the second insulator layer inside the coil. And a portion.

According to the present invention, when a relatively small DC current is flowing through the coil, a large inductance value is obtained, and even if a relatively large DC current flows through the coil, the inductance value does not rapidly decrease. Superimposition characteristics can be obtained.

It is a perspective view of the electronic component which concerns on embodiment of this invention. It is a disassembled perspective view of the laminated body of the electronic component which concerns on one Embodiment of this invention. FIG. 2 is a cross-sectional structural view taken along line AA of the electronic component in FIG. It is the graph which showed the result of computer simulation. It is the perspective view which showed the manufacturing process of the ceramic green sheet which should become a magnetic body layer. FIG. 6 is a cross-sectional structure view taken along the line AA of an electronic component according to another embodiment.

Hereinafter, an electronic component according to an embodiment of the present invention will be described.

(Configuration of electronic parts)
Hereinafter, an electronic component 10a according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view of

electronic components

10a and 10b according to an embodiment of the present invention. FIG. 2 is an exploded perspective view of the multilayer body 12a of the electronic component 10a according to the first embodiment. FIG. 3 is a sectional structural view taken along the line AA of the electronic component 10a of FIG. Hereinafter, the stacking direction of the electronic component 10a is defined as the z-axis direction, the direction along the long side of the electronic component 10a is defined as the x-axis direction, and the direction along the short side of the electronic component 10a is defined as the y-axis direction. To do. The x axis, the y axis, and the z axis are orthogonal to each other.

The electronic component 10a includes a laminate 12a and external electrodes 14a and 14b as shown in FIG. The laminated body 12a has a rectangular parallelepiped shape and incorporates a coil L. The external electrodes 14a and 14b are each electrically connected to the coil L, and are provided so as to cover the side surfaces located at both ends in the x-axis direction.

As shown in FIG. 2, the laminated body 12a is formed by laminating magnetic layers (insulator layers) 16a to 16k and a nonmagnetic layer (insulator layer) 17. Furthermore, the laminated body 12a includes a high magnetic permeability portion 19 (see FIG. 3) described later. The magnetic layers 16a to 16k are made of ferromagnetic ferrite (for example, Ni—Zn—Cu ferrite). The nonmagnetic layer 17 is made of a material having a lower magnetic permeability than the magnetic layers 16a to 16k. In the present embodiment, the nonmagnetic layer 17 is made of nonmagnetic ferrite (for example, Zn—Cu ferrite). The nonmagnetic layer 17 is provided in the stacked body 12a, and more specifically, is provided between the magnetic layer 16e and the magnetic layer 16f. In FIG. 2, the magnetic layers 16a to 16k are constituted by eleven magnetic layers, but the total number of the magnetic layers 16a to 16k is not limited to this. Further, only one nonmagnetic layer 17 is provided, but two or more layers may be provided. Hereinafter, when referring to the individual magnetic layers 16a to 16k, an alphabet is appended to the reference symbol, and when referring to these, the alphabet after the reference symbol is omitted.

The coil L is a spiral coil that advances in the z-axis direction while rotating as shown in FIG. That is, the coil axis X of the coil L extends along the z-axis direction as shown in FIG. In the present embodiment, the coil axis X is parallel to the z-axis direction. Thereby, the nonmagnetic layer 17 intersects the coil axis X. As shown in FIG. 2, the coil L includes coil conductors 18a to 18f and via-hole conductors b1 to b5.

As shown in FIG. 2, the coil conductors 18a to 18f are provided on the main surfaces of the

magnetic layers

16d and 16e, the nonmagnetic layer 17, and the magnetic layers 16f to 16h, respectively. Each of the coil conductors 18a to 18f is made of a conductive material made of Ag, has a length of 7/8 turns, and is arranged so as to overlap each other in the z-axis direction. As a result, the coil L constituted by the coil conductors 18a to 18f forms a rectangular ring when viewed in plan from the z-axis direction. The length of the coil conductors 18a to 18f is not limited to 7/8 turns. In the following, when referring to the individual coil conductors 18a to 18f, an alphabet is appended to the reference symbol, and when referring to these, the alphabet after the reference symbol is omitted.

As shown in FIG. 2, each of the via-hole conductors b1 to b5 is provided so as to penetrate the

magnetic layers

16d and 16e, the nonmagnetic layer 17, and the magnetic layers 16f and 16g in the z-axis direction. The via-hole conductors b1 to b5 function as connecting portions that connect the ends of the adjacent coil conductors 18 when the magnetic layers 16a to 16k and the nonmagnetic layer 17 are laminated. More specifically, the via-hole conductor b1 connects the end of the coil conductor 18a where the lead-out portion 20a is not provided and the end of the coil conductor 18b. The via-hole conductor b2 connects the end of the coil conductor 18b to which the via-hole conductor b1 is not connected and the end of the coil conductor 18c. The via hole conductor b3 connects the end of the coil conductor 18c to which the via hole conductor b2 is not connected and the end of the coil conductor 18d. The via-hole conductor b4 connects the end of the coil conductor 18d to which the via-hole conductor b3 is not connected and the end of the coil conductor 18e. The via-hole conductor b5 includes an end of the coil conductor 18e that is not connected to the via-hole conductor b4, and an end of the coil conductor 18f that is not provided with the lead-out portion 20b. Is connected. Thereby, the coil conductors 18a to 18f and the via-hole conductors b1 to b5 constitute a spiral coil L.

The high magnetic permeability portion 19 has a higher magnetic permeability than the magnetic layer 16 and, as shown in FIGS. 2 and 3, the z-axis direction so as to cross the non-magnetic layer 17 inside the coil L. It is provided to extend. As shown in FIGS. 2 and 3, the high magnetic permeability portion 19 has a coil axis within a rectangular region formed by being surrounded by the coil conductors 18a to 18f when viewed in plan from the z-axis direction. X is provided so as to overlap with X. The high magnetic permeability portion 19 is composed of magnetic layers 19d to 19i. As shown in FIG. 2, the magnetic layers 19d to 19i are respectively

magnetic layers

16d and 16e and nonmagnetic layer 17 in regions surrounded by the coil conductors 18a to 18f when viewed in plan from the z-axis direction. And the magnetic layers 16f to 16h are provided so as to penetrate in the z-axis direction. Then, the magnetic layers 16a to 16k and the nonmagnetic layer 17 are laminated, so that the magnetic layers 19d to 19i constitute a prismatic high permeability portion 19. Hereinafter, when referring to the individual coil conductors 18a to 18f and the magnetic layers 19d to 19i, an alphabet is appended to the reference symbol, and when these are collectively referred to, the alphabet after the reference symbol is omitted. .

Further, as shown in FIG. 2, each of the coil conductors 18a and 18f has

lead portions

20a and 20b at the ends thereof. The

lead portions

20a and 20b are drawn to the side surfaces of the multilayer body 12a and connected to the external electrodes 14a and 14b, respectively. Thereby, the coil L is connected to the external electrodes 14a and 14b.

(effect)
The electronic component 10a configured as described above has a large inductance value when a relatively small DC current is flowing through the coil L, as will be described below, and a relatively large DC current. Even if it flows through the coil L, it has a DC superposition characteristic in which the inductance value does not rapidly decrease.

More specifically, in the electronic component 10a, the nonmagnetic layer 17 is provided so as to cross the coil L. As a result, even if a relatively large direct current flows through the coil L, magnetic saturation is suppressed from occurring in the stacked body 12a, and an abrupt decrease in inductance value due to magnetic saturation is suppressed. Further, in the electronic component 10a, a high magnetic permeability portion 19 having a magnetic permeability higher than that of the magnetic layer 16 is provided inside the coil L. Therefore, when a small direct current that does not cause magnetic saturation in the high magnetic permeability portion 19 flows through the coil L, a sufficient inductance value can be obtained. Here, as an electronic component used for a DC-DC converter, it operates with a stable inductance value when a large current flows, and can exhibit excellent conversion efficiency when a small current flows. It is necessary to operate with a large inductance value. Therefore, the electronic component 10a can be suitably used for such a DC-DC converter.

The inventor of the present application performed the following computer simulation in order to make the effect of the electronic component 10a clearer. First, this inventor produced the electronic component 10a as a 1st model. In addition, the inventor of the present application manufactured an electronic component 10a in which the high magnetic permeability portion 19 is not provided as a second model according to the comparative example. And the change of the inductance value was computed by changing the direct current passed through the first model and the second model. FIG. 4 is a graph showing the results of this computer simulation. The vertical axis represents the inductance value, and the horizontal axis represents the direct current.

As shown in FIG. 4, in the second model, since the nonmagnetic layer 17 is provided, even when a relatively large DC current flows through the coil L, a rapid decrease in the inductance value is suppressed. ing. However, in the second model, when a relatively small direct current flows through the coil L, a large inductance value cannot be obtained.

On the other hand, in the first model, a high permeability portion 19 is provided in addition to the second model. Therefore, when a relatively small DC current flows through the coil L, an inductance value higher than that of the second model can be obtained. Even when a relatively large direct current flows through the coil L, a stable inductance value can be obtained. Therefore, according to this computer simulation, even if a relatively large direct current flows through the coil L in the electronic component 10a, the occurrence of magnetic saturation in the stacked body 12a is suppressed, and the inductance value due to magnetic saturation is reduced. It can be seen that the rapid decrease is suppressed.

(Method for manufacturing electronic parts)
Below, the manufacturing method of the electronic component 10a is demonstrated, referring drawings. Hereinafter, a method for manufacturing one electronic component 10a will be described. However, in practice, a mother laminated body is produced by laminating mother ceramic sheets, and the mother laminated body is cut to simultaneously obtain a plurality of electronic components 10a.

First, ferric oxide (Fe ₂ O ₃ ), zinc oxide (ZnO), nickel oxide (NiO), and copper oxide (CuO) were weighed at a predetermined ratio and each material was put into a ball mill as a raw material, and wet blended I do. The obtained mixture is dried and pulverized, and the obtained powder is calcined at 800 ° C. for 1 hour. The obtained calcined powder is wet pulverized by a ball mill, dried and crushed to obtain a first ferrite ceramic powder.

A binder (vinyl acetate, water-soluble acrylic, etc.), a plasticizer, a wetting material, and a dispersing agent are added to the first ferrite ceramic powder, mixed by a ball mill, and then defoamed by reduced pressure. The obtained ceramic slurry is formed into a sheet shape on a carrier sheet by a doctor blade method and dried to produce a ceramic green sheet to be the magnetic layer 16.

Next, each material obtained by weighing ferric oxide (Fe ₂ O ₃ ), zinc oxide (ZnO) and copper oxide (CuO) at a predetermined ratio is put into a ball mill as a raw material, and wet blending is performed. The obtained mixture is dried and pulverized, and the obtained powder is calcined at 800 ° C. for 1 hour. The obtained calcined powder is wet pulverized by a ball mill, dried and then crushed to obtain a second ferrite ceramic powder.

To this second ferrite ceramic powder, a binder (vinyl acetate, water-soluble acrylic, etc.), a plasticizer, a wetting material and a dispersing agent are added and mixed by a ball mill, and then defoamed by reduced pressure. The obtained ceramic slurry is formed into a sheet shape on a carrier sheet by a doctor blade method and dried to produce a ceramic green sheet to be the nonmagnetic layer 17.

Next, ferric oxide (Fe ₂ O ₃ ), zinc oxide (ZnO), nickel oxide (NiO), and copper oxide (CuO) are weighed at a predetermined ratio, and the respective materials are put into a ball mill as raw materials. Mix. At this time, the respective materials are mixed so that the ratio of nickel oxide (NiO) is lower than that of the first ferrite ceramic powder. The obtained mixture is dried and pulverized, and the obtained powder is calcined at 800 ° C. for 1 hour. The obtained calcined powder is wet pulverized by a ball mill, then dried and crushed to obtain a third ferrite ceramic powder.

To this third ferrite ceramic powder, a binder (vinyl acetate, water-soluble acrylic, etc.), a plasticizer, a wetting material, and a dispersing agent are added and mixed with a ball mill. Ceramic slurry used for the body layers 19d to 19i is obtained.

Next, as shown in FIG. 2, the ceramic green to be the

magnetic layers

16d and 16e provided with the coil conductors 18a to 18f and the magnetic layers 19d to 19i, the nonmagnetic layer 17 and the magnetic layers 16f to 16h. A sheet is produced. Hereinafter, a ceramic green sheet to be the magnetic layer 16e will be described as an example. FIG. 5 is a perspective view showing a manufacturing process of a ceramic green sheet to be the magnetic layer 16e.

First, a ceramic green sheet to be a magnetic layer 16e with a carrier film 22e as shown in FIG. 5 (a) is prepared. Next, as shown in FIG. 5B, a hole H2 to be the magnetic layer 19e and a via hole h2 to be the via-hole conductor b2 are formed by irradiating a laser beam or the like. At this time, the laser beam is irradiated while adjusting the strength so that only the ceramic green sheet is burned out and the carrier film 22e is not burned out.

Next, as shown in FIG. 5C, the ceramic slurry used for the magnetic layer 19e is filled into the holes H2 by screen printing or the like. Finally, as shown in FIG. 5D, a conductive paste mainly composed of Ag, Pd, Cu, Au, or an alloy thereof is screen printed on the ceramic green sheet to be the magnetic layer 16e. The coil conductor 18b is formed by coating by a method such as photolithography. Further, in the step of forming the coil conductor 18b, the via hole h2 is filled with a conductive paste to form the via hole conductor b2. In addition, since formation of the coil conductor 18 grade | etc., To the ceramic green sheet which should become the other magnetic body layer 16 and the nonmagnetic body layer 17 is formed by the process similar to the coil conductor 18b, description is abbreviate | omitted.

Next, as shown in FIG. 2, the ceramic green sheets to be the magnetic layers 16a to 16e, the nonmagnetic layer 17 and the magnetic layers 16f to 16k are stacked so as to be arranged in this order from the positive direction side in the z-axis direction. . More specifically, a ceramic green sheet to be the magnetic layer 16k is disposed. Next, the ceramic green sheet to be the magnetic layer 16j is disposed and temporarily pressed onto the ceramic green sheet to be the magnetic layer 16k. Thereafter, the ceramic green sheets to be the

magnetic layers

16i, 16h, 16g and 16f, the nonmagnetic layer 17 and the

magnetic layers

16e, 16d, 16c, 16b and 16a are similarly laminated and temporarily pressed in this order. To obtain a mother laminate. Further, the mother laminate is subjected to main pressure bonding by a hydrostatic pressure press or the like.

Next, the mother laminated body is cut into a laminated body 12a having a predetermined size by pressing to obtain an unfired laminated body 12a. This unfired laminate 12a is subjected to binder removal processing and firing. The binder removal treatment is performed, for example, in a low oxygen atmosphere at 500 ° C. for 2 hours. Firing is performed, for example, at 1000 ° C. for 2 hours.

The fired laminated body 12a is obtained through the above steps. The laminated body 12a is chamfered by barrel processing. Thereafter, a silver electrode to be the external electrodes 14a and 14b is formed on the surface of the laminated body 12a by applying and baking an electrode paste whose main component is silver by a method such as dipping. The silver electrode is dried at 120 ° C. for 10 minutes, and the silver electrode is baked at 890 ° C. for 1 hour. Finally, the external electrodes 14a and 14b are formed by performing Ni plating / Sn plating on the surface of the silver electrode. Through the above steps, an electronic component 10a as shown in FIG. 1 is completed.

(Other embodiments)
The electronic component according to the present invention is not limited to the electronic component 10a, and may be changed within the scope of the gist thereof. FIG. 6 is a cross-sectional structural view taken along line AA of the electronic component 10b according to another embodiment.

In the electronic component 10 a, the high magnetic permeability portion 19 is provided so as to penetrate the nonmagnetic layer 17. On the other hand, in the electronic component 10b, the high magnetic permeability portion 19 is provided separately on each of the positive direction side and the negative direction side in the z-axis direction of the nonmagnetic layer 17. Also in the electronic component 10b having such a structure, it is possible to achieve the same operational effects as the electronic component 10a.

Further, in the electronic component 10a, the high magnetic permeability portion 19 forms one prism, but the structure of the high magnetic permeability portion 19 is not limited to this. For example, the magnetic layers 19d to 19i may be provided on the magnetic layers 16d to 16h without forming the holes H. In this case, in the coil L, the magnetic layers 19d to 19i and the magnetic layers 16d to 16h are alternately arranged.

In the

electronic components

10a and 10b, the nonmagnetic layer 17 is provided. However, instead of the nonmagnetic layer 17, a magnetic layer having a magnetic permeability lower than that of the magnetic layer 16 may be provided. .

INDUSTRIAL APPLICABILITY The present invention is useful for electronic components. Particularly, when a relatively small direct current flows through the coil, a large inductance value can be obtained, and even if a relatively large direct current flows through the coil, Further, it is excellent in that a direct current superimposition characteristic in which the inductance value does not decrease can be obtained.

L coil X coil axis b1 to b5 via

hole conductor

10a, 10b electronic component 12a laminated body 14a, 14b external electrode 16a to 16k, 19d to 19i magnetic body layer 17 nonmagnetic body layer 18a to 18f coil conductor 19

high permeability portion

20a, 20b drawer

Claims

A laminate in which a plurality of first insulator layers are laminated;
A coil built in the laminate and having a coil axis extending along the lamination direction;
With
The laminate is
A second insulator layer having a lower magnetic permeability than the first insulator layer and provided in the stacked body so as to intersect the coil axis;
A high permeability portion having a higher magnetic permeability than the first insulator layer, and provided in each of an upper side and a lower side in the stacking direction of the second insulator layer inside the coil; ,
Further including,
Electronic parts characterized by
The high permeability portion is provided so as to cross the second insulator layer;
The electronic component according to claim 1.
The second insulator layer is a non-magnetic layer;
The electronic component according to claim 1, wherein: