JP3159201B2 - Multilayer inductor and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multilayer inductor and a method of manufacturing the same, and more particularly, to a multilayer inductor suitable for use in a high frequency range and a method of manufacturing the same.

[0002]

2. Description of the Related Art FIG. 4 is a schematic cross-sectional view showing a laminated inductor 1 of interest to the present invention.

[0003] The multilayer inductor 1 includes a multilayer body 3 formed by stacking a plurality of insulating layers 2 made of, for example, ceramic.

A coil conductor 4 is formed inside the laminate 3. The coil conductor 4 is not shown in detail,
It has a portion extending along the interface of the insulating layer 2 and a portion extending through the insulating layer 2 in the thickness direction, such as a via-hole connection portion, and these two portions provide an overall coil-like form. The illustrated portion of the coil conductor 4 is:
This is a portion extending along the interface of the insulating layer 2.

The coil conductor 4 has first and second lead-out portions 7 and 8 extending to, for example, opposing first and second end surfaces 5 and 6 of the laminate 3, respectively. Inside, a first neighborhood path 9 extending from the first lead-out portion 7 along the interface of the insulating layer 2 and passing near the second end surface 6 and extending from the second lead-out portion 8 to the vicinity of the first end surface 5 It has a second neighboring path 10 through which it passes.

The first and second end faces 5 of the laminate 3
First and second external electrodes 11 and 12 are formed on and 6 respectively. These first and second external electrodes 11 and 12 are electrically connected to first and second lead portions 7 and 8 of the coil conductor 4, respectively.

[0007]

The above-mentioned external electrode 11
And 12 are usually formed by applying a conductive paste on the end faces 5 and 6 of the laminate 3 and baking it.

As best shown in FIG. 4, first and second external electrodes 11 and 12 are not only formed on first and second end faces 5 and 6, respectively,
First and second adjacent surface extensions 1 extending from a first or second end surface 5 or 6 onto a portion of an adjacent surface
3 and 14. These adjacent surface extension portions 13 and 14 are not necessarily required in terms of the function of the multilayer inductor 1, but as described above,
When 1 and 12 are formed by applying and baking a conductive paste, usually, they are necessarily formed, and as the laminated inductor 1 becomes smaller, the adjacent surface extensions 13 and 14 are formed on the adjacent surface. , The ratio of the extended region increases.

Similarly, considering the miniaturization of the multilayer inductor 1, in order to obtain a desired inductance as efficiently as possible, the coil conductor 4 is formed in a wide range within the multilayer body 3 as much as possible. It is preferable to do so.

From the above situation, the first external electrode 1
The first adjacent surface extension 13 faces the second neighboring path 10 of the coil conductor 4 via the insulating layer 2, and
The adjacent surface extension 14 of the second external electrode 12 faces the first neighboring path 9 of the coil conductor 4 via the insulating layer 2. Here, in the active state of the multilayer inductor 1, between the adjacent surface extension 13 of the first external electrode 11 and the second neighboring path 10 of the coil conductor 4, and between the adjacent surface extension of the second external electrode 12. It should be noted that a relatively large potential difference has occurred between 14 and the first neighboring path 9 of the coil conductor 4.

As a result, the opposing region 15 between the second neighboring path 10 of the coil conductor 4 and the adjacent surface extension 13 of the first external electrode 11 and the first neighboring path 9 of the coil conductor 4 and the second In the facing region 16 between the external electrode 12 and the adjacent surface extension 14, the capacitance C _{S1 that} cannot be ignored
And C _S2 will occur. Multilayer inductor 1
Is smaller, the insulating layers 2 located in the opposing regions 15 and 16 are thinner, and thus the capacitances C _S1 and C _{S2 are} larger.

The capacitances C _S1 and C
_S2 acts on the equivalent circuit of the multilayer inductor 1 in a state of being connected in parallel with the inductance formed by the coil conductor 4, as shown in FIG.

Therefore, these capacitances C _S1 and C _S1
S2 has a greater effect at higher frequencies, and more specifically, causes a problem of lowering the self-resonant frequency of the multilayer inductor 1 and narrowing its use frequency region.

An object of the present invention is to provide a multilayer inductor and a method of manufacturing the same, which can reduce the above-mentioned undesired capacitance and thereby prevent the self-resonant frequency from lowering. It is to be.

[0015]

According to a first aspect of the present invention, there is provided a multilayer inductor having a laminated body formed by laminating a plurality of insulating layers, and a coil extending as a whole. And a first and a second lead-out portion respectively drawn to different first and second end surfaces of the laminate, and extending from the first lead-out portion along the interface of the insulating layer inside the laminate. Formed on the first and second end surfaces of the laminate, respectively, so as to be electrically connected to the coil conductor and the first and second lead portions, respectively, having a nearby path passing near the second end surface. And first and second external electrodes, wherein the second external electrode is located on one side of a surface adjacent to the second end face so as to face a path adjacent to the coil conductor via the insulating layer. Adjacent surface extending to the upper part Have a section, in order to solve the technical problems described above, the facing area between the adjacent surfaces extensions of neighboring path and the second external electrode of the coil conductor, the opposed territory
It is characterized in that a gap having an area covering the area is provided.

A second aspect of the multilayer inductor according to the present invention is more specific about the above-described neighboring path and adjacent surface extension.

In the second aspect, the laminated inductor according to the present invention has a laminated body formed by laminating a plurality of insulating layers and a form extending in a coil shape as a whole. It has first and second lead-out portions respectively drawn to first and second end surfaces different from each other, and extends from the first lead-out portion along the interface of the insulating layer inside the laminated body, and has a second end surface. A coil conductor having a first near path passing near and a second near path extending from the second lead-out portion and passing near the first end face;
A first external electrode and a second external electrode formed on first and second end faces of the laminate so as to be electrically connected to the first and second lead-out portions, respectively;
Has a first adjacent surface extension extending from the first end surface to a portion adjacent to the second end surface of the coil conductor so as to face the second adjacent path of the coil conductor via the insulating layer. A second external electrode extending from the second end surface to a part of a surface adjacent thereto so as to face the first neighboring path of the coil conductor via the insulating layer; In order to solve the above-mentioned technical problem, an opposing area between the second adjacent path of the coil conductor and the first adjacent surface extension of the first external electrode and the coil are provided. An air gap having an area covering each of the opposing regions is provided in an opposing region between the first neighboring path of the conductor and the second adjacent surface extension of the second external electrode.

The present invention is advantageously applied particularly when the insulating layer is made of a dielectric ceramic.

In the multilayer inductor according to the present invention, the gap may be provided so as to substantially cover a region of the multilayer body where the coil conductor is formed.

The present invention is also directed to a method for manufacturing a multilayer inductor as described above.

A method of manufacturing a laminated inductor according to the present invention includes a raw ceramic layer for providing an insulating layer, a conductive paste for providing a coil conductor, and a burnable material for providing a void, and firing. A step of preparing a raw laminate, which becomes a laminate for a multilayer inductor, and a step in which the raw ceramic layer becomes an insulating layer, the conductive paste becomes a coil conductor, and the burnable material burns away Baking the green laminate so as to form voids, and placing the first laminate on the first and second end surfaces of the fired laminate.
And forming a second external electrode.

In order to obtain the above-mentioned green laminate, typically, a conductive paste for providing a coil conductor or a burnable material for providing a void is formed on a ceramic green sheet to be a green ceramic layer. The method is applied in advance as necessary, and a method of forming a green laminate by stacking these ceramic green sheets is employed, or a raw ceramic layer, a conductive paste for providing a coil conductor, and a void are provided. Or by printing a burnable material to give a green laminate in a desired order.

[0023]

FIG. 1 is a sectional view schematically showing a multilayer inductor 21 according to an embodiment of the present invention.

The multilayer inductor 21 includes a plurality of insulating layers 2
2 is provided. The insulating layer 22
In this embodiment, it is made of a non-magnetic material, for example, a dielectric ceramic.

A coil conductor 24 is formed inside the laminate 23. Although not shown in detail, the coil conductor 24 has a portion extending along the interface of the insulating layer 22 and a portion extending through the insulating layer 22 in the thickness direction such as a via hole connection portion. This gives a form extending in a coil shape as a whole. Coil conductor 24
1 is a portion extending along the interface of the insulating layer 22.

The coil conductor 24 is provided with first and second lead-out portions 27 and 2 which are drawn out to first and second end surfaces 25 and 26 different from each other of the laminate 23, respectively.
Eight. In this embodiment, the first and second end faces 25 and 26 are located so as to face each other. Depending on,
Another end face of the laminate may be selected.

The coil conductor 24 is also provided in the first lead portion 2 along the interface of the insulating layer 22 inside the laminate 23.
7 extending from the second end face 26 and passing through the vicinity of the second end face 26 and the first end face 25 extending from the second drawer 28.
Has a second proximity path 30 passing through the vicinity.

The first and second drawers 27 and 28 are electrically connected to the first and second drawers 27 and 28, respectively.
On the first and second end faces 25 and 26 of the laminate 23, the first and second external electrodes 31 and 3 are provided, respectively.
2 are formed. These external electrodes 31 and 32 are formed, for example, by applying a conductive paste on first and second end faces 25 and 26 and baking them.

The first external electrode 31 is connected to the first
Has a first adjacent surface extension 33 that extends from the end surface 25 to a portion of the adjacent surface. The first adjacent surface extension 33 is provided with the second
In the vicinity of the vicinity route 30.

Further, the second external electrode 32 is
Has a second adjacent surface extension 34 that extends from the second end surface 26 to a portion of the adjacent surface. The second adjacent surface extension 34 is connected to the coil conductor 24 via the insulating layer 22.
Is opposed to the first neighborhood route 29 of the first embodiment.

A characteristic configuration of the laminated inductor 21 is that an opposing area 35 between the second neighboring path 30 of the coil conductor 24 and the adjacent surface extension 33 of the first external electrode 31 is provided in the opposing area. An air gap 36 having an area covering 35 is formed, and an opposing area 37 between the first adjacent path 29 of the coil conductor 24 and the adjacent surface extension 34 of the second external electrode 32 is provided in the opposing area 37. Is provided in a space 38 covering an area . The thickness of these gaps 36 and 38 is
It is selected from several μm to several tens μm.

In order to manufacture the laminated inductor 21 provided with such gaps 36 and 38, for example, the following method is adopted.

First, in order to obtain the laminate 23, the insulating layer 22
Ceramic layer for providing coil conductors, conductive paste for providing coil conductors 24, and voids 36 and 38
A raw laminate is provided, which is provided with a burnable material for providing

More specifically, as shown in FIG. 2, a plurality of ceramic green sheets 39a, 39b, 39c,... To be green ceramic layers are prepared. Fig. 2 (1)
The ceramic green sheet 39a shown in FIG. 2 is located on the outermost side, the ceramic green sheet 39b shown in FIG. 2B is located on the inner side, and the ceramic green sheet 39b shown in FIG. Sheet 39c
Are stacked so as to be positioned.

On the ceramic green sheet 39c shown in FIG. 2C, the first of the coil conductors 24 shown in FIG.
The conductive paste film 40 for providing the lead portion 27 and the first neighboring path 29 is illustrated. The conductive paste film 40 has a via hole connection portion 41 indicated by a broken line.
, A coil conductor 24 extending in the form of a coil as a whole is formed by being successively connected to the conductive paste film on the ceramic green sheet stacked thereunder.

As shown in FIG. 2 (2), on one of the ceramic green sheets 39b located between the ceramic green sheets 39a and 39c, a void forming paste film 42 containing a burnable material is formed. You. This paste film 42 for forming a gap is formed by the gap 38 shown in FIG.
And the first neighboring path 2 of the coil conductor 24
9 is formed so as to substantially cover the same.

Although not shown in FIG. 2, the other space 3
The paste film for void formation for 6 is formed on another ceramic green sheet in the same manner.

The ceramic green sheet 3 shown in FIG.
A plurality of ceramic green sheets including 9a to 39c are stacked and pressed as necessary to obtain a green laminate, and the green laminate is fired to obtain the laminate shown in FIG. 23 is obtained. By this firing step, the ceramic green sheets 39a,
39b, 39c,... Become the insulating layer 22, the conductive paste film 40 and the like become coil conductors, and the void-forming paste film 42 and the like become voids 38 or 36. As a burnable material contained in the void forming paste film 42 or the like, for example, carbon or an organic substance can be advantageously used.

FIG. 3 is a diagram corresponding to FIG.
2 is an equivalent circuit diagram of the multilayer inductor 21 shown in FIG.

In the facing region 35 shown in FIG. 1, the capacitance C1 is formed by the insulating layer 22 between the first adjacent surface extension 33 and the gap 36, and the capacitance C2 is formed by the gap 36. Then, the capacitance C3 is formed by the insulating layer 22 between the gap 36 and the second neighboring path 30.
In the facing area 37, the second adjacent surface extension 3
The capacitance C4 due to the insulating layer 22 between the
Is formed, the capacitance C5 is formed by the gap 38, and the insulating layer 22 between the gap 38 and the first neighboring path 29 is formed.
This forms the capacitance C6.

As shown in FIG. 3, the above-mentioned capacitance C1
C3 are connected in series between them, and are connected in parallel with the inductance provided by the coil conductor 24. The capacitances C4 to C6 are connected in series between them, and are connected in parallel to the inductance provided by the coil conductor 24.
Therefore, also in this laminated inductor 21, the capacitance is formed in parallel with the inductor. In addition, the dielectric ceramic as a non-magnetic material used for forming the insulating layer 22 in this type of laminated inductor 21 has a relative dielectric constant of about 40 to 50, so that the capacitance C1, C3, C4, and C6 can be relatively large.

However, since the relative permittivity of the air providing the gaps 36 and 38 is only 1, the capacitances C2 and C5 can be set to relatively small values. Moreover, the capacitances C1 to C3 and the capacitance C4
To C6 are connected in series. For this reason, the capacitance applied in parallel to the coil conductor 24 can be significantly reduced by forming the air gaps 36 and 38. As a result, the self-resonant frequency of the multilayer inductor 21 can be prevented from lowering, and the usable frequency range of the multilayer inductor 21 can be expanded.

As described above, the present invention has been described with reference to the illustrated embodiment.
Various modifications are possible.

For example, in the multilayer inductor 21 according to the illustrated embodiment, the first and second neighboring paths 2
Although air gaps 36 and 38 are provided in connection with both 9 and 30, it should be understood that only one of air gaps 36 and 38 is provided within the scope of the present invention.

The plane shapes of the gaps 36 and 38 are as follows:
Although it can be inferred from the shape of the void forming paste film 42 shown in FIG. 2B, the shape may be changed to another planar shape. For example, as shown by a two-dot chain line in FIG. 2B, the gap may be provided so as to substantially cover a region where the coil conductor 24 is formed in the laminate 23. In this case, a gap may be provided so as to exclude a region shown by a broken line in FIG.

The gaps 36 and 38 are formed in the facing region 3
5 and 37, each may be provided in a plurality of layers.

In the above-described embodiment, the insulating layer 22
Is made of a dielectric ceramic, but may be made of a magnetic ceramic or a material other than ceramic.

Regarding the method of manufacturing the laminated inductor 21, in order to obtain a raw laminated body, in the above-described embodiment, a plurality of ceramic green sheets 39a, 39b,
Although the method of stacking 39c,... Is adopted, a method of applying a raw ceramic layer, a conductive paste, and a burnable material by printing in a desired order may be adopted.

[0049]

As described above, according to the multilayer inductor of the present invention, the extension of the adjacent surface of the one external electrode and the one of the coil conductor in the region where the potential difference is relatively large in the multilayer inductor. A facing area extending from a lead portion connected to the other external electrode different from the external electrode and a neighboring path passing near the end face on the one external electrode side, and a gap having an area covering the facing area; Is provided, the capacitance generated in this region can be reduced. Therefore, it is possible to prevent the self-resonant frequency of the multilayer inductor from being lowered by such capacitance, and it is possible to expand the use frequency range of the multilayer inductor.

In the multilayer inductor according to the present invention, the coil conductor has first and second lead-out portions that are respectively drawn to first and second end surfaces different from each other of the multilayer body, and the inside of the multilayer body has There is a first neighboring path extending from the first lead portion along the interface of the insulating layer and passing near the second end face, and a second neighboring path extending from the second lead part and passing near the first end face. And a first external electrode formed on the first end face of the multilayer body is separated from the first end face such that the first external electrode faces the second neighboring path of the coil conductor via the insulating layer. Having a first adjacent surface extension extending over a portion of the surface adjacent to;
A second external electrode formed on a second end face of the laminate,
When having a second adjacent surface extension extending from the second end surface to a part of a surface adjacent thereto so as to face the first adjacent path of the coil conductor via the insulating layer, region facing <br/> between the facing region and the first neighboring path and a second abutment surface extension between the second neighboring path and the first abutment surface extension, respectively, each opposite region if so provided gap area covering the can enhance the effect of reducing the capacitance.

Further, in the multilayer inductor according to the present invention, when the insulating layer is made of dielectric ceramic, the occurrence of capacitance that cannot be ignored becomes a more significant problem.
As described above, the present invention is particularly advantageously applied to a multilayer inductor including an insulating layer made of a dielectric ceramic.

Further, when the above-mentioned gap is provided so as to substantially cover the region where the coil conductor is formed in the laminate, the effect of reducing the capacitance is further enhanced.

According to the method of manufacturing a multilayer inductor according to the present invention, a burnable material is used to form a void, and the burnable material is burned at the same time as the ceramic firing step. A void having a desired shape can be efficiently and easily formed.

[Brief description of the drawings]

FIG. 1 is a sectional view schematically showing a multilayer inductor 21 according to an embodiment of the present invention.

FIG. 2 shows ceramic green sheets 39a and 39 for explaining a method for obtaining the laminate 23 shown in FIG.
It is a top view of b, 39c, ....

FIG. 3 is an equivalent circuit diagram provided by the multilayer inductor 21 shown in FIG.

FIG. 4 is a sectional view schematically showing a conventional multilayer inductor 1 of interest to the present invention.

FIG. 5 is an equivalent circuit diagram provided by the multilayer inductor 1 shown in FIG.

[Explanation of symbols]

 Reference Signs List 21 laminated inductor 22 insulating layer 23 laminated body 24 coil conductor 25 first end surface 26 second end surface 27 first lead portion 28 second lead portion 29 first near path 30 second near path 31 first External electrode 32 second external electrode 33 first adjacent surface extension 34 second adjacent surface extension 36, 38 gap 39a, 39b, 39c ceramic green sheet 40 conductive paste film 42 gap formation paste film

Claims (5)

(57) [Claims] 1. A laminated body formed by laminating a plurality of insulating layers, wherein the laminated body has a form extending in a coil shape as a whole, and is drawn out to first and second end faces different from each other of the laminated body. A coil having first and second lead-out portions and a near path extending from the first lead-out portion along the interface of the insulating layer inside the laminate and passing near the second end surface. First and second external electrodes formed on the first and second end faces of the laminate, respectively, so as to be electrically connected to the conductor and the first and second extraction portions, respectively. Wherein the second external electrode extends from the second end surface to a part of a surface adjacent thereto so as to face the near path of the coil conductor via the insulating layer. With surface extension A multilayer inductor, wherein the opposing region is formed in an opposing region between the neighboring path of the coil conductor and the adjacent surface extension of the second external electrode.
A multilayer inductor, wherein a void having an area to cover is provided. 2. A laminated body formed by laminating a plurality of insulating layers, wherein the laminated body has a form extending in a coil shape as a whole, and is drawn out to first and second end faces different from each other of the laminated body. A first near path extending from the first lead along the interface of the insulating layer inside the laminate and passing near the second end face; A coil conductor having a second proximity path extending from the second extraction portion and passing near the first end face; and the coil conductors being electrically connected to the first and second extraction portions, respectively. First and second external electrodes formed on the first and second end faces of the laminate, respectively, wherein the first external electrode is connected to the first and second external electrodes via the insulating layer. Facing the nearby route 2 So that the first
A first surface extending from an end surface of the
, And the second external electrode is arranged so that the second external electrode faces the first near path of the coil conductor via the insulating layer.
A second surface extending from the end surface of the
Wherein the opposing area is provided between the second adjacent path of the coil conductor and the first adjacent surface extension of the first external electrode. and the opposing region between the second abutment surface extension of the first neighboring path between the second external electrode of the coil conductors, respectively, the gap area covering each face region is provided A multilayer inductor, characterized in that: 3. The multilayer inductor according to claim 1, wherein the insulating layer is made of a dielectric ceramic. 4. The multilayer inductor according to claim 1, wherein the gap is provided so as to substantially cover a region of the multilayer body where the coil conductor is formed. 5. A method for manufacturing a multilayer inductor according to claim 1, wherein a green ceramic layer for providing the insulating layer and a conductive layer for providing the coil conductor. A paste and a burnable material for providing the voids are provided, and a raw laminate that becomes the laminate by firing is prepared.The raw ceramic layer is the insulating layer, and the conductive paste is The green laminate is fired so as to become the coil conductor and the burnable material is burned off to form the voids, and the green laminate is fired on the first and second end surfaces of the fired laminate. A method for manufacturing a multilayer inductor, comprising: forming respective first and second external electrodes.